67樣品準備、分析和安全採樣治理和質量保證合格人員對Stillwater和East Boulder Mines使用的地質數據收集標準程序感到滿意,這些程序規定的方法與行業標準一致。Stillwater和East Boulder Mines的治理系統依賴指令控制措施,因此使用內部手冊(標準程序)來管理和標準化數據收集、驗證和存儲。此外,標準程序是強制性指令,規定了可接受的方法和步驟,以執行與持續收集、驗證、處理、審批和存儲用於地質建模和礦產資源評估的地質數據有關的各種任務。除了內部標準程序外,Sibanye-Stillwater還實施了一項內部分析質量控制協議,用於對實驗室性能和實驗室分析數據的質量進行例行評估。根據協議的要求,送往實驗室的樣品批次包括常規的“空白”樣品(掛牆和下壁斜長巖樣品)和實驗室分析過的以前樣品批次的紙漿樣品(重複樣品)。分析質量控制的結果在第8.4節中討論。治理系統還強調培訓,以達到在數據收集、驗證和存儲方面履行具體職能所需的能力水平。對新的地質學家進行了廣泛的在職培訓,他們最終將負責測井和取樣。巖性和巖土數據是通過記錄從地面和地下鑽探中回收的鑽芯獲得的。來自以前巖心測井的現有鑽孔信息指導正在進行的巖心測井,監督測井的地質學家將進一步調查在測井過程中觀察到的與預期巖石類型和地層序列的任何偏差。常規驗證由經驗豐富的地質學家在數據收集流程中的各個階段關口進行,最終驗證由合格人員執行。合格人員指出,數據的內部同行審查有助於在最後確定收集數據之前及早發現數據收集中的重大錯誤。治理系統的另一個方面是記錄地質數據收集流程(即數據收集、處理和驗證)。合格人員承認,該文件有助於流程活動和結果以及為糾正異常或虛假數據而採取的措施的可審核性。Stillwater和East Boulder Mines的地表核心存儲設施是安全的,並由授權的地質人員進入。此外,這些設施是礦場地面基礎設施的一部分,這些礦場被柵欄隔開,以防止公眾和動物未經授權進入,Sibanye-Stillwater美國PGM運營部門的員工只能進入。暗礁取樣在Stillwater和East Boulder Mines的取樣程序中,需要對J-M暗礁中含有可見硫化物礦物的所有礦化交叉點進行取樣。在這種採樣中,考慮到硫化物礦化丰度和巖性的變化,突破68個採樣間隔至關重要。此外,取樣中斷應始終發生在吊壁接觸處。這種方法有助於對採樣截面的分析結果進行有效評估。對於BQ大小的鑽芯,實驗室要求的最小樣品大小相當於1英尺(以前為0.5英尺,但實驗室要求已改為600克樣品相當於1英尺)。因此,在1英尺到3英尺的片段中採集珊瑚礁樣本,然後將樣本延伸1英尺到3英尺,進入礦化交叉點的底牆和懸掛牆。採樣可能會進一步延伸到礦化的下盤地帶。當採樣大的內部廢棄區時,採樣長度也可以改變,採樣間隔可以延長到4英尺,或者由於惡劣的地面條件,在鑽井過程中只回收了一小部分已鑽取的巖心,在這種情況下,需要取下鑽區塊之間完整的5英尺。礦化區之間小於10英寸的內部廢物區應與礦化區一起取樣,但被指定為零等級。鑑於J-M礁非常粗粒的性質,為了確保樣品的代表性,將整個鑽芯樣品提交給分析實驗室,不進行巖芯劈裂。 在地質學家將樣本運送到實驗室之前,這些樣本被分配了唯一的樣本識別號和標籤。此外,斯蒂爾沃特礦的每個鑽孔的樣本和相關質量控制樣本(重複樣本和空白樣本)在採樣當天提交給實驗室,如果不合格,則應在第二天上午提交。由於樣本量低於斯蒂爾沃特礦,東博爾德礦的樣本應在採樣後兩週內提交。地質學家準備隨樣本一起的樣本提交表。樣本和樣本提交表都被放置在定製的箱中,實驗室人員從中接收樣本。樣本數據的記錄在Ore QMS數據庫中捕獲。樣品製備和分析實驗室來自Stillwater和East Boulder礦的樣品在位於哥倫布冶金綜合體的內部分析實驗室進行分析,該實驗室由Sibanye-Stillwater擁有和運營。合格人員可以確認分析實驗室是一個安全的設施,因為它位於哥倫布冶金設施內,該設施是用柵欄隔開的,以防止公眾未經授權進入,並且只有獲得授權的Sibanye-Stillwater美國PGM運營人員才能進入。內部實驗室擁有樣品製備和化學分析的設施(通過火災分析和儀器技術)。它配備了實驗室信息管理系統(LIMS)軟件,有助於有效和高效地管理樣本和相關數據。2011年,分析實驗室實現了自動化,配備了波長色散和能量色散X射線熒光(XRF)儀器以及機器人樣品製備設施。它處理69個地質鑽芯和品位控制樣品,以及來自選礦廠、冶煉廠和賤金屬精煉廠的樣品。該實驗室未經任何標準協會認證。合格人員不認為沒有認證是一個實質性問題,因為實驗室由六個國際認可的實驗室組成的小組定期對內部樣本進行外部檢查。此外,合格人員在履行其正常職責時,定期檢查實驗室設施,與實驗室人員互動,並評估實驗室的分析數據。這些活動的目的是發現和消除實驗室用於地質樣品的樣品製備、分析設備和方法中的任何重大問題。 引入AGL每天處理300個地質樣本,提高樣本製備過程的一致性。這是對現有流程的升級,現有流程具有每天200個地質樣本的分析能力。 該實驗室採用行業一致的方法來樣本接收、製備和分析以及分析結果報告。來自Stillwater和East Boulder Mines的鑽芯樣本通過第三方運輸公司以手提包運送到哥倫布倉庫。實驗室人員從哥倫布倉庫的現場車輛貨艙中取回手提袋。實驗室收到的樣本批次與提交表進行核對,並在樣本製備之前向地質學家報告發現的任何差異,以進行糾正。 樣品製備包括樣品乾燥、粉碎和研磨。鑽探芯樣約4。4磅至11磅的質量在221°F的温度下乾燥約兩個小時,組織成包含多達22個樣品的組,並分配帶有條形碼的標籤。條形碼樣品標籤被掃描並記錄到LIMS中,之後樣品通過一臺主要和第二臺頜式破碎機進行操作,生產的材料等級為100%,超過0.25英寸。粉碎後用於縮小樣品大小的過程由機器人設備執行,從而將偏差或採樣誤差的可能性降至最低。粉碎的材料使用Jones Riffle分離器被分割成大約0.40磅到0.44磅,並被引入機器人樣品製備系統(HPM1500)。該系統在自動化研磨機中對每個樣品進行順序粉碎,使其達到95%,達到140目(即106微米粒度)標準。研磨試驗每季度進行一次,以確保始終達到正確的研磨尺寸。分析是通過XRF分析和鉛火分析(PBFA)收集的雙重分析路線進行的,然後是電感耦合等離子體光譜分析(ICP-OES),用於金屬含量的測定。在PBFA過程中,銀作為助收劑被引入熔劑中,以幫助收集地質樣品中的貴金屬。XRF和PBFA+ICP-OES分析技術產生的結果都是總體分析,反映了Stillwater和East Boulder礦礦產資源聲明中報告的目標金屬(Pd和Pt)的潛在可提取原地價值。70將一部分粉碎的材料稱重,與粘結劑混合,然後裝載到自動顆粒壓榨機中。用於給火試樣充電的天平要經過精確度測試,每一班都需要使用經過認證的檢重。 對壓制後的丸粒進行X射線熒光分析。剩餘的樣本材料被帶到火試平衡室。火焰分析(FA)過程包括以下步驟:在2084°F用基於鉛的助熔劑熔融原樣和標準樣品;分離鉛以形成鉛按鈕;杯形以形成貴金屬珠(多溴聯苯併火焰原子吸收);珠在王水中消化;以及通過消解液的電感耦合等離子體發射光譜儀分析金屬含量。所有分析結果都通過儀器直接報告給LIMS,並以電子方式轉發給地質學家,從而消除了數據捕獲錯誤的風險。所用分析過程的儀器檢測下限(LDL)為Pd為5 ppb,鉑為10 ppb。XRF分析也會產生多種元素和氧化物的結果,但LIMS被配置為只報告PGM評估所需的重要元素(Pd和Pt)。對於PBFA採集和電感耦合等離子體發射光譜分析,只確定了鉑、鈀和金的值,儘管只報告了鈀和鉑值。在最終確定分析報告之前,將XRF分析報告的PD數據與基於PBFA收集技術的PD數據進行比較。在報告最終定稿之前,任何差異都會得到調查和糾正。實驗室制定了分析和處理樣品的質量保證和控制程序。實驗室對低品位(如地質)樣品和高品位(如精礦)樣品的接收、製備和分析分別運行不同的生產線,並保持總體較高的清潔度,以最大限度地減少污染。此外,實驗室標準和空白也包括在每個樣品批次中,並按要求處理質量控制樣品中發現的任何異常情況。 實驗室使用這些內部標準來監控分析準確性,並應地質學家的要求向他們提供標準的分析數據。 合格人員對分析實驗室的樣品製備、分析方法、準確度和精密度以及清潔水平感到滿意。由於哥倫布綜合體被圍欄隔開,以防止公眾未經授權進入,並且僅限Sibanye-Stillwater US CGM運營部的授權人員進入該設施,因此合格人員對實驗室在製備和分析期間的樣本安全性感到滿意。所採用的分析方法適合J-M Reef的礦化類型和品位,並廣泛用於CGM行業。 因此,來自實驗室的分析數據是等級估計的合適輸入。


71分析質量控制質量控制程序的性質和範圍Sibanye-Stillwater執行一項分析質量控制協議,要求Stillwater和East Boulder礦的地質學家持續監測實驗室業績。該議定書自2006年以來一直在使用。提交給實驗室的所有礦山樣品批次包括基質匹配的空白樣品(取自掛牆斜長巖和下盤斜長巖)和地質學家為評估實驗室在污染和分析精確度方面的表現而引入的重複(紙漿)樣品。精選紙漿樣品以監測2E級光譜的精度,如下所示:0.00-0.19opt(廢物)、0.20-0.49opt(低等級)、0.50-0.99opt(高等級)和1.00opt及以上(極高等級)。一般而言,東Boulder礦和Stillwater礦東段和西段樣品批次中包括的質量控制樣品的插入率確保每個區域每月至少分析10個空白樣品和10個重複樣品。目前,沒有獨立供應商編制的J-M珊瑚礁認證標準物質(標準),Stillwater和East Boulder Mines的地質人員依靠實驗室人員引入地質樣品流中的內部開發標準(MF系列標準)的分析結果來監測實驗室分析程序的準確性。對重複樣本和空白樣本分析數據的分析是一個持續的過程,發現的任何問題都會由地質和實驗室人員進行調查和糾正。這項評估還包括:在任何分析結果被接受到礦石質量管理系統數據庫之前,對實驗室的樣品結果進行審查,以發現異常的鉑/鈀比例或異常高的品位;在巖心測井過程中做出的可視硫化物礦物估計與分析結果被接受到礦石質量管理系統數據庫後的品位之間的比較。在沒有明顯可見硫化物礦物的情況下,記錄和調查了沒有相關/預期的鉑和鈀值或鉑和鈀較高的硫化物礦物的賦存狀態;以及控制圖上的異常重複和空白樣本數據和標準數據的識別,以確定數據中的任何趨勢。如果這些步驟中的任何一個顯示可能存在問題的跡象,地質學家要求重新分析受影響的樣品或樣品批次。自2006年以來收集的Stillwater和East Boulder Mines的重複樣本數據在收集過程中不斷進行審查,但為了本TRS的目的,合格人員使用控制圖進一步審查,如圖23和圖24分別顯示的Stillwater和East Boulder Mines的絕對平均誤差和散點圖。絕對平均誤差小於10%或相關係數的平方(R2)值顯示較高的分析精度。一般來説,Stillwater和East Boulder Mines的重複數據分別有88%和94%,72表示分析方法的高精度(平均百分比差異0.8%)。然而,接近儀器分析檢測下限的低品位樣品(即來自廢棄區)往往與低精度有關,這些樣品分別佔East Boulder和Stillwater礦重複樣品數據集的6%和12%。此外,出現異常數據的情況是孤立的,如果不能解決異常數據,則需要重新分析受影響的樣本或拒絕接受結果。在大多數情況下,第二次和第三次分析具有可比性,這表明問題與地質人員的樣本選擇和標記(即樣本交換和錯誤標記)有關,而不是實驗室的低精確度。圖23:Stillwater礦重複數據分析圖24:東Boulder礦重複樣本數據分析Stillwater和East Boulder礦使用的空白材料沒有經過認證的價值。因此,空白樣本數據在曲線圖上進行可視分析,以確定可能表明嚴重污染或樣本交換的異常值。自2006年以來收集的Stillwater和East 73 Boulder礦的空白樣本數據也由合格人員為本TRS的目的進一步審查(圖25)。一般而言,兩個礦場的空白樣本值相似,大多數空白樣本值低於用於珊瑚礁和廢物區分的0.2opt等級閾值,這排除了存在壓倒性交叉樣本污染的情況。雖然沒有證據表明樣品受到嚴重污染,但合格人員建議包括Pd和鉑含量不高的認證空白材料,以明確評估實驗室的任何污染程度。圖25:Stillwater和East Boulder礦的空白樣本數據分析合格人員從實驗室獲得內部標準分析數據,以評估對地質樣本進行分析的準確度。實驗室提供了標準材料MF-14至MF-23的數據以及表10所示的適用預期(平均值)值、控制下限(LCLS)和控制上限(UCL)。使用圖26至圖33中的控制圖對數據進行了分析,所有這些數據都顯示了標準分析數據的可接受的準確度和精密度水平。因此,與這些內部標準一起分析的樣品批次的分析數據被認為可以納入礦產資源估計數據庫。表10:內部標準名稱標準説明詳情PD(Ppm)鉑(Ppm)MF-14預期16.87 4.82 LCL 15.99 4.37 UCL 17.96 5.2 MF-15預期7.65 1.61 LCL 7.32 1.48 UCL 7.97 1.74 MF-16預期7.52 1.58 74 LCL 7.25 1.46 UCL 7.8 1.71 MF-18預期4.23 0.93 LCL 4.06 0.85 UCL 4.58 1.07MF-20預期14.97 3.72 LCL 13.85 2.81 UCL 16.07 4.63 MF-21預期9.41 1.95 LCL 8.87 1.73 UCL 9.95 2.16 MF-22預期1.41 8.06 LCL 1.25 7.59 UCL 1.58 8.52 MF-23預期1.16 6.85 LCL 0.90 6.12 UCL 1.42 7.58圖26:實驗室標準MF-14數據分析圖27:實驗室標準MF-15數據分析


75圖28:實驗室標準MF-16數據分析圖29:實驗室標準MF-18數據分析圖30:實驗室標準MF-20數據分析76圖31:實驗室標準MF-21數據分析圖32:實驗室標準MF-22數據分析圖33:實驗室標準MF-23數據分析因此,來自內部實驗室的分析數據具有可接受的完整性,可用於礦產資源評估。77數據驗證數據存儲和數據庫管理Stillwater和East Boulder Mines的所有鑽孔數據(即,鑽頭和井下測量、巖性、巖土、結構、分析和礦化數據)都存儲在Ore QMS數據庫中,這是一個內部構建的數據庫,旨在標準化鑽井過程中的信息收集。數據以電子方式從核心記錄儀系統導入數據庫。庫表、關鍵字段和代碼是Ore QMS數據庫中可用的驗證工具,用於確保條目正確。Ore QMS數據庫存儲在備份它的中央IT服務器上,並具有嚴格的控制(例如,密碼保護和訪問限制),以確保數據的安全性和完整性。存儲在Ore QMS數據庫中的鑽孔數據被導出到Maptek VulcanTM(Vulcan)建模軟件環境,從而提供額外的備份。合格人員對數據存儲和驗證以及數據庫管理做法感到滿意,這些做法都與行業實踐保持一致。數據庫驗證內部生成的地面勘探和地下定義鑽孔數據是用於Stillwater和East Boulder Mines的地質建模和礦產資源評估的主要數據。合格人員沒有對收集的數據進行獨立核查。獨立核查將需要對全部或部分歷史樣本進行重新抽樣和重新分析,以確認數據庫中跨越數十年的鑽孔數據,這是不切實際的。因此,合格人員審查了在持續數據收集和處理過程中進行的嚴格核查,並對核查的結果和結論以及數據庫中存儲的歷史數據的質量感到滿意。礦場採用的數據收集和驗證程序已經使用了幾十年。所使用的地表地形測量數據來源於美國地質調查局,並通過與歷史測量數據的比較來驗證這一點。研究發現,高分辨率地形調查數據比以往礦產資源量估算所用的歷史調查數據具有更高的準確性。鑽孔數據的驗證是一個連續的過程,在數據收集、導入礦石質量管理系統數據庫之前和之後以及在地質建模和礦產資源評估過程中的不同階段完成。由於合格人士為Sibanye-Stillwater的全職員工,他們對在礦山收集的鑽孔數據進行或監督驗證,然後批准和簽署驗證的數據以進行礦產資源評估。歷史數據在收集過程中由以前的合格人員進行了驗證,這些驗證也得到了當前合格人員的確認。這兩個礦的礦產資源評估是基於Sibanye-Stillwater及其前身收集的經過驗證的鑽孔數據,這些數據存儲在Ore QMS數據庫中。Stillwater和East Boulder礦目前的鑽孔數據庫分別包含與51 289個和11 568個鑽孔有關的數據。該數據庫包含靜水礦111 535種化驗方法和東博爾德礦84 603種化驗方法。在這些測試中,分別有50164次和33180次測試被確定為與“礦帶”(即礦物資源78評估切割)樣品有關,分別用於Stillwater和East Boulder Mines。經過數據驗證,2023年Stillwater礦和East Boulder礦的礦產資源量估算分別使用了50 164個和10 385個鑽孔的礦帶綜合數據。一般來説,巖性數據是通過對地面和地下金剛石巖心鑽探回收的鑽芯進行常規地質錄井來獲得的。記錄鑽探巖心的地質學家訓練有素,熟悉J-M礁、下盤和懸壁的地層和巖石類型。此外,他們還受到經驗豐富的地質學家的監督,他們審查和批准他們的記錄表。巖心錄井是根據標準化數據收集和每個鑽孔測井所需的細節類型的標準程序進行的,任何偏差或異常條目都由Ore QMS數據庫系統中提供的內置驗證工具標記。在巖心錄井期間,地質學家還會考慮現有的鑽孔信息,監督錄井的高級地質師會進一步調查任何偏離預期巖石類型和地層序列的情況。分析數據以電子方式從實驗室接收,並以電子方式輸入數據庫,在數據庫中與相關的巖性和測量數據相結合。在最終確定進口之前,根據第8節討論的分析質量控制協議,對分析數據進行評估、驗收以供使用並存儲在數據庫中。4.所有鑽孔測量數據均由總測量師審核和簽署。地質學家還通過將調查數據與計劃座標進行比較,並通過在Vulcan軟件環境中進行目測檢查來驗證調查數據。Ore QMS數據庫的導入和驗證由經驗豐富的地質人員執行。在Ore QMS數據庫中,通過對條帶日誌(綜合巖心調查、巖性和化驗數據的日誌)進行抽查,並使用內置的驗證工具來驗證數據是否有缺失和不正確的條目。還使用Vulcan程序腳本定期檢查鑽孔數據庫,該腳本在數據導入過程中自動檢查缺失、重疊或顛倒的分析間隔。其他驗證包括將測量數據庫條目與測量的底板側向巷道的3D模型進行比較,以驗證井眼接箍座標、方位和傾角。將每個鑽孔的井下金屬剖面與每個地質域的預期剖面進行比較,並進一步調查和解決任何差異。合格人士承認,用於Stillwater和East Boulder礦礦產資源評估的廣泛鑽孔數據庫已得到嚴格驗證。在收集過程中、在礦石質量管理系統數據庫中以及在地質建模和礦產資源評估過程中,在關鍵點對數據進行持續驗證。合格人員參加或監督了由受過適當培訓的人員進行的一些驗證。有資格的人也


79批准使用經驗證的鑽孔數據,該數據已被批准用於礦產資源評估。合資格人士確認,數據驗證與行業慣例一致,而所收集的數據的數量和類型適合於J-M珊瑚礁PGM礦化的性質和類型。80選礦和冶金測試冶金測試和可選性哥倫布冶金綜合體的Stillwater和East Boulder選礦廠、冶煉廠和賤金屬精煉廠最近沒有完成任何相關的冶金測試工作。合格人士認為,沒有必要進行測試工作,因為Stillwater和East Boulder選礦廠以及Columbus冶金綜合設施都已經運行了幾十年,並在多年來進行了升級和修改,以考慮到新技術和增加的產能。第14節詳細討論了選礦過程,並給出了各種已安裝設備的工藝流程圖。這些工藝流程圖基於符合行業標準的PGM工藝流程和技術。所有操作都有詳細的流程圖、質量平衡和冶金會計明細表。J-M礁礦石的冶金和礦物學特徵已為人熟知,礦石加工和選礦作業的冶金回收是基於多年積累的詳細歷史生產數據。1)。自2017年以來,來自Stillwater East(Blitz)區段的礦石一直在Stillwater選礦廠加工。該礦石的選礦經驗表明,該區段的J-M礁在冶金上與Stillwater West區段的J-M礁相似,礦石在Stillwater選礦廠的選礦過程中沒有表現出任何不同。有害元素合資格人士並不知悉在Stillwater及East Boulder選礦廠加工J-M礁礦所產生的精礦中有任何有害元素的報告。該等礦場生產的礦石已成功加工數十年,合資格人士認為有理由預期J-M珊瑚礁的未開採部分不會有任何有害元素。由於處理設施都已經運行了幾十年,因此既沒有必要進行大規模試驗,也沒有必要進行中試。81礦產資源估算背景利用與Stillwater和East Boulder礦的50 164個和10 385個鑽孔有關的廣泛鑽孔數據庫,對J-M珊瑚礁和礦產資源估算進行三維地質建模。由Sibanye-Stillwater人員在內部執行的J-M珊瑚礁和礦產資源評估的3D地質建模基於適合礦山J-M珊瑚礁的建築、礦化風格和變異性的通用評估流程和方法。該流程是完善的,並規定在礦產資源評估過程中的關鍵點由合格人員進行強制性檢查和驗證。Stillwater和East Boulder礦礦產資源評估的參考點是J-M礁材料的現場噸位和品位估計,其最終有合理的經濟開採前景。此外,還完成了對鈀和鉑的綜合品位(2e)和生物礁厚度的估計,但沒有估計出現在低丰度的副產品或副產品。自Stillwater和East Boulder Mines的採礦和礦石加工作業開始以來,J-M珊瑚礁中沒有發現有害元素。因此,沒有估計到有害元素。對於在Stillwater和East Boulder礦最終被歸類為已測量、指示或推斷的礦產資源,採用了一致的估計和評估方法。該方法與對其他表列PGM珊瑚礁採用的傳統估計和評價方法保持一致,這些表列珊瑚礁具有長範圍厚度和等級連續性的特點。合格人士假設,未採空區的J-M珊瑚礁將表現出採空區觀察到的長期厚度和等級連續性以及整體礁石特徵。因此,假設J-M礁鑽孔交點厚度和坡度連續,樣點之間採用基於簡單克立格法的坡度內插。根據PGM生物礁評價方法,估算/評價的關鍵參數(變量)為2E級、2E級的長度積累(即礁寬與2E級的乘積)、體積和密度。本評估報告第11.2至11.6節討論了評估流程和報告的估計數的詳細情況。 82地質建模和解釋區拾取和評價切割確定主區構成了JM礁的礦化良好經濟部分,該部分包含在稱為珊瑚礁通道的礦產資源評價切割中。然而,評價切割中還包括局部存在的礦化充分的山腳材料。用於3D地質建模的主區交叉點由地質學家通過稱為區域拾取的手動過程識別和選擇。地質學家使用掛牆作為參考,因為80%至90%的主區交叉口發生在掛牆附近。其餘部分(10%至20%)由被鎂鐵質侵入體、斷層或其他地質特徵破壞的交叉點組成,在生成評估削減時需要額外的地質審查和勤奮。此外,在Stillwater和East Boulder Mines地區,礦化發生在與主帶不同但2E級相似的下盤巖石中。下盤礦化傾向於不連續。由於反向斷裂作用,在Stillwater礦還有一個重複(重複)礦化的區域。這兩個礦都遵循共同的區塊採選方法。對於每個鑽孔,驗證的分析數據與相關的巖性和樣品數據相結合,以生成用於分層挑選的綜合測井表(條帶測井)。區域拾取需要掃描鑽孔的綜合原木,以確定J-M珊瑚礁包裹的懸壁。從上盤接觸處,下伏礦化帶(主帶和直接下盤單元的礦化部分)以0.20 opt的綜合2E品位門檻識別和圈定。對於每個鑽孔J-M礁交叉點,為所選擇的部分分配唯一的標識符地質碼,指示這些部分可以被包括在評估切割數據集中。分區拾取還包括考慮特定鑽段和相鄰鑽段中的相鄰鑽孔,以確保分區截齒在鑽孔和鑽段之間的順利延伸以及解釋中的地質一致性。對於2E品位低於0.20 opt的礦化較差的生物礁交匯處,在懸壁接觸處標明單一的次礦石品級值。如果由於鑽芯中完全缺乏任何硫化物礦物而沒有收集到分析數據,則0。在建模期間,這些交叉點被指定為相當於儀器低密度脂蛋白的2E等級。在這些交叉口上挑選區域需要地質學家的勤奮和經驗,因為有10%至20%的交叉點位於下盤(局部的下盤礦化),需要識別地質結構(如鎂鐵質侵入體和斷層)的重複或幹擾。這些礦化的下盤地帶和重複的主要地帶標有唯一的地帶識別號,允許對這些地帶進行單獨的評估和建模。合資格人士對用於區分礦化區和廢物區的區劃方法感到滿意,因為這適合於J-M礁的性質和風格,並確保用於地質建模和評估的礁組合的劃定保持一致。合格人士指出,用於區域挑選(珊瑚礁航道劃定)的0.20/2e品位門檻是保守的,因為這高於用於礦產資源的截止品位


83人報到。然而,礦產資源報告的最小開採寬度(厚度)可能比礁石水道寬,這證明有理由使用較高品位的區域採摘門檻。數據處理和分析11.2.2.1按照合成行業慣例進行評估切割(礁道)數據處理和分析。在分區挑選和編碼之後,每個鑽孔的評估切割數據(包括接箍和井下測量)、每個鑽孔的地層、巖性和分析數據被導入Vulcan,並通過稱為反測量的自動化過程整合和定位到正確的三維(3D)空間。通過整合數據進行以下驗證:檢查樣本分析、接箍測量、井下測量和巖性數據,以確保所有鑽孔都有關於關鍵估計變量的完整數據;檢查數據,以檢查空間誤差;檢查分析數據,以查明超出範圍和異常的數據;以及檢查樣本間隔,以查明樣本之間的重疊和無法解釋的差距。驗證後的綜合數據通過地質編碼在Vulcan中進行合成,並使用每個區塊(評價巖層)的鑽井接箍測量、方位角、傾角和分析數據。這一過程產生了新的X、Y和Z接箍座標、鉑、鈀和2E的單一合成值以及每個鑽井主區交叉點的厚度(真實厚度和表觀厚度)。通過對評價斷面中的樣本等級進行長度加權平均,得出了鑽孔綜合等級。複合數據被用於地質塊體建模以及品位和厚度估計。11.2.2。 在統計分析之前,審查了Stillwater和East Boulder Mines的評估切割數據集,以識別等級中的任何剩餘零值。零值被2 E的LDL值替換(0.0001opp或3.125 ppb)和厚度(0.01英尺),以防止因等級和厚度為零而導致克里金方程中負權重的問題。用LDL值取代零值(更正)也提高了低等級地區的估計精度。最初按礦場和在Stillwater和East Boulder礦場按領域對評估切割的長度加權組合進行了統計分析。圖9和圖10顯示了Stillwater和East Boulder Mines Mines的域。由於Boulder的數據稀疏,東域和西域與青蛙塘西相結合,而黃銅猴子東西域與青蛙塘東相結合進行當前評估。因此,青蛙池塘西部的估計參數被應用於Boulder域,青蛙池塘東部的參數被應用於黃銅猴子區塊。84綜合數據的統計數據分析涉及構建厚度與2E等級的散點圖以評估它們之間的任何相關性以及等級(2E)的直方圖以確定總體分佈特徵。使用複合數據(圖34和圖35)生成的未稀釋水平厚度(UHW)與2E品位的散點圖(圖34和圖35)表明這些變量之間沒有相關性,但決定根據PGM部門的實踐間接估計等級作為等級厚度累積。圖34:超高含水率與2E品位的散點圖R?=0.0347 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 C o m p o S it e 2 E G rad d e(O P T)未稀釋水平寬度(Ft)85圖35:東巨石礦綜合超高含水率與2E品位的散點圖對2E數據的直方圖分析(圖36和圖37)顯示了正偏態分佈和異常值(異常值)。 圖36:斯蒂爾沃特礦複合2 E品位的柱狀圖R² = 0.058 0 1 2 3 4 5 6 0 5 10 15 20 25 30 35 40 45 50 C o m p osite 2 E G ra d e(op t)未稀釋水平厚度(ft)86圖37:東博爾德礦場封蓋綜合2 E等級的柱狀圖是在2 E等級上進行的,並評估了關鍵變量,即礁水道真實寬度(FCW),未稀釋水平寬度(單位為英尺)和等級-厚度累積稱為英尺盎司/噸(FOZPT),這是FCW和2 E等級的產物。表11中列出的斯蒂爾沃特礦和東博爾德礦使用的上限值被選為東博爾德礦的斯蒂爾沃特礦和蛙池東和西所有區域的第98百分位數,以使採礦期間礦山觀察到的模型品位和實際品位保持一致;由於數據稀疏,黃銅猴和博爾德區塊的上限設定在第99百分位數。然而,主管人士承認,這些保守的封頂值對掩蓋珊瑚礁的實際潛力產生了影響,特別是在Stillwater礦,那裏的離羣值等級是真實的,而且往往與舞廳有關。宴會廳是珊瑚礁上含有異常數量的PGM的局部區域,對J-M珊瑚礁的開採具有重大的積極影響。表11:礦產資源評估礦域封頂價值UHW(Ft)2E(Opt)FOZPT FCW(Ft)Stillwater Blitz 24.40 2.67 32.79 23.74 Blitz West 15.90 2.44 17.71 15.01 DOL 21.30 2.64 15.51 14.44 DOWU 21.60 1.70 11.46 14.46 OSEE 17.80 4.19 31.07 17.05 OSEW 17.00 4.00 26.75 15.22 OSW 18.00 3.93 29.13 15.82 UWE 17.50 3.31 19.34 13.72 BLK2-OSW 22.00 4.85 40.05 19.50 BLK2-UWE 22.40 3.99 26.20 17.30東Boulder青蛙池東19.20 1.56 11.62 14.71青蛙池西19.12 1.53 11.61 14.71黃銅猴子E&W 19.06 1.51 11.13 14.60 Boulder E&W 18.57 1.57 11.68 14.22


87 11.2.2.3地統計學分析綜合FOZPT、UHW和FCW數據也在Supervisor中進行地統計學分析,以確定適當的估算方法和要使用的估算參數。地質統計分析包括評估Stillwater和East Boulder Mines的2E、FOZPT、UHW和FCW綜合數據的空間趨勢。據觀察,這些變量表現出各向異性行為(空間趨勢),如圖38所示的Stillwater礦的FCW和圖39所示的East Boulder礦的FOZ。因此,對Stillwater和East Boulder Mines的每個區域的三個變量分別建立了歸一化變異函數模型,並對與礦產資源有關的FOZPT、FCW、UHW和2E建立了變異函數結果。圖38:FCW連續性的空間分析圖39:東Boulder礦FOZ連續性的空間分析表12:FOZPT雷域塊金結構1結構2 Sill 1 Range 1(Ft)Range 3(Ft)Sill 2 Range 1(Ft)Range 2 Range 1(Ft)Range 3(Ft)Sill 2 Range 1(Ft)Range 3(Ft)Stillwater Blitz 0.36 0.45 159 142 250 0.26 587 327 500 Blitz West 0.44 041 173 143 250 0.15 921 760 500 OSWU 0.46 0.43 136 160 250 0.11 1102 886 500 OSWU 0.46 0.43 136 160 250 011 1102 886 500 OSEW 0.46 0.48 146 157 250 0.06 1102 762 500 OSEW 0.44 0.38 167 252 250 0.18 887 605 500 UWE 0.47 0.31 142 250 0.22 513 368 500 88礦山領域金塊結構1結構2門檻1範圍1(英尺)範圍2(英尺)範圍3(英尺)門檻2範圍1(英尺)範圍2(英尺)範圍3(英尺)範圍3(英尺)DOWL0.43 0.34 130 84 250 0.23 490 620 500 DOWU 0.43 0.35 59 94 250 0.22 409 426 500 West Fork East & West 0.43 0.48 245 374 250 0.09 1112 826 500 East Boulder Frog Pond East & West 0.42 0.45 65 95 250 0.13 850 680 500黃銅猴東西方0.42 0.45 65 95 250 0.13 850 680 500博爾德東西方0.42 0.45 65 95 250 0.13 850 680 500表13:FCW礦域金塊結構1結構2 Sill 1範圍1(ft)範圍2(ft)範圍3(ft)範圍2(ft)範圍3(ft)範圍2(ft)範圍3(ft)範圍2(ft)範圍3(ft)範圍3(ft)斯蒂爾沃特閃電戰0.38 0.44 180 151 250 0.18 806 589 500西部閃電戰0.44 0.41 173 143 250 0.15 921 760 500 OSWU 0.46 0.43 136 160 250 0.11 1102 886 500 OSWL 0.46 0。43 136 160 250 0.11 1102 886 500 OSEW 0.46 0.48 146 157 250 0.06 1102 762 500 OSEE 0.44 0.38 167 252 250 0.18 887 605 500 UWE 0.46 0.38 126 126 250 0.16 803 555 500 DOWL0.43 0.45 152 110 250 0.12 1086 826 500 DOWU 0.43 0.39 74 104 250 0.18 844 667 500 West Fork East & West 0.43 0.48 245 374 250 0.09 1112 826 500東博爾德蛙池東& W 0.39 0.47 98 95 250 0.14 719 527 500黃銅猴東& W 0.39 0.47 98 95 250 0.14 719 527 500博爾德東& W 0.39 0.47 98 95 250 0.14 719 527 500表14:ULW礦山領域金塊結構1結構2 Sill 1範圍1(ft)範圍2(ft)範圍3(ft)範圍2(ft)範圍3(ft)範圍2(ft)範圍3(ft)範圍2(ft)範圍3(ft)範圍3(ft)斯蒂爾沃特閃電戰0.36 0.45 159 142 250 0.26 587 327 500西部閃電戰0.44 0.41 173 143 250 0.15 921 760 500 OSWU 0.46 0.43 136 160 250 0.11 1102 886 500 OSWL 0.46 0.43 136 160 250 0.11 1102 886 500 OSEW 0.46 0.48 146 157 250 0.06 1102 762 500 OSEE 0.44 0.38 167 252 250 0.18 887 605 500 UWE 0.47 0.31 142 142 250 0.22 513 368 500 DOWL0.43 0.34 130 84 250 0.23 490 620 500 DOWU 0.43 0.35 59 250 0.22 409 426 500 West Fork East & West 0.43 0.48 245 374 250 0.09 1112 826 500 East Boulder Frog Pond East & West 0.39 0.42 88 94 250 0.19 490 322 500 Brass Monkey East & West 0.39 0.42 88 94 250 0.19 490 322 500 Boulder East & W 0.39 0.42 88 94 250 0.19 490 322 500表15:2 E Mine Area Nugget結構1結構2 Sill 1範圍1(ft)範圍2(ft)範圍3(ft)範圍2(ft)範圍3(ft)Sill 2範圍1(ft)範圍2(ft)範圍3(ft)範圍3(ft)斯蒂爾沃特閃電戰0.38 0.45 133 200 250 0.17 887 642 500西部閃電戰0.44 0.41 173 143 250 0.15 921 760 500 OSWU 0.46 0.44 109 160 250 0 0.10 893 876 500 OSWL 0.46 0.44 109 160 250 0.10 893 876 500 OSEW 0.46 0.48 146 157 250 0.06 1102 762 500 OSEE 0.44 0.49 133 153 250 0.07 887 605 500 UWE 0.46 0.39 102 157 250 0.15 826 823 500 DOWL0.43 0.51 140 106 250 0.06 969 683 500 DOWU 0.43 0.45 92 184 250 0.12 840 806 500 West Fork East & West 0.43 0.51 140 106 250 0.06 969 683 500蛙塘E&W 0.44 0.49 192 156 250 0.07 1049 719 500 89雷域金塊結構1結構2 Sill 1 Range 1(Ft)Range 3(Ft)Sill 2 Range 1(Ft)Range 2(Ft)Range 3(Ft)東Boulder黃銅猴子E&W 0.44 0.49 192 156 250 0.07 1049 719 500 Boulder E&W 0.44 0.49 192156 250 0.07 1049 719 500合格人員對FOZPT的雙結構變異函數模型感到滿意,由域複合數據構造的FCW、UHW和2E表明達到了二階平穩,這意味着通過簡單或普通的克立格插值法進行等級估計是合適的。模擬的變異函數還表明,金塊與基牀的比值適中,這得到了現有的近距離數據的支持,並且是典型的礁型PGM礦牀。同樣,表12至表15所示的變異函數範圍與在採空區觀察到的礁體連續性一致,同時也是典型的礁型PGM礦牀。構造建模和地質損失確定通過區劃劃分的評估切割提供了J-M珊瑚礁潛在的經濟部分的輪廓,這些部分可以建模以報告為礦產資源。構造解釋先於J-M珊瑚礁經濟部分的三維地質建模。在Stillwater和East Boulder礦劃定的大多數主要構造是通過挖溝和地表測繪查明的,或者是根據現有的航空磁測和鑽孔數據進行解釋的。正在進行的地下測繪和地下定義鑽探產生了額外的密集數據,用於完善這兩個礦山的結構模型。值得注意的地質構造是在Stillwater礦發現的區域南草原斷層和馬人斷層。然而,還有許多其他中等規模的斷層和堤壩,它們是在Vulcan和LeapFrog中獨立建模的,以納入最終的3D地質模型。南大草原斷裂與JM-Reef近平行,與JM-Reef相交或產於礁的懸壁中,造成Stillwater礦山部分區域(如外海井西地區)的礁體重複。騎士斷層是一個反向斷層,它也抵消了JM-Reef。這些斷層和基底斷層(一種“盲目”逆衝斷層)是在Stillwater礦模擬的。鑽孔數據庫包含堤壩和斷層截距的標準化巖石代碼,用於構建每個地質結構的模型。在目前的評估中,斷層和巖牆輪廓使用現有數據在Vulcan中數字化,地質構造輪廓(折線)被導入LeapFrog軟件環境,在該環境中構建線框並將其投影到礦產資源足跡的極限。在可能的情況下,斷層被建模為3D空間中的平面,使用鑽探數據和下盤側向漂移的地質測繪信息。堤壩被建模為三維實體。巖牆和斷層模型在J-M礁的3D建模過程中得到了應用(圖40至圖43)。因此,珊瑚礁的3D地質模型已經清楚地説明瞭地質損失。額外的地質損失計入了噸位估計數,以説明90個未知地質結構可能造成的損失。未知的地質結構(主要是堤壩)是根據在Stillwater和East Boulder Mines的採空區收集的地雷調節數據估計的。未知地質損失3.5%和5%。 合格人員承認,小規模斷層不會造成地質損失,也不會需要改變礦山設計,因為這些斷層是通過地下采礦作業開採的。因此,沒有估計因不明小規模斷層而造成的未知地質損失。然而,這些斷層在採礦過程中帶來了地質工程和品位稀釋的挑戰,因此在詳細的礦山規劃中得到了考慮。地質解釋與線框建模將編碼後的評價切割數據導入LeapFrog進行三維地質塊體建模,並對數據進行解測。珊瑚礁航道的地質建模是基於LeapFrog提供的“靜脈系統”隱式線框建模工具。在Stillwater和East Boulder Mines的大多數地質模型足跡上,J-M礁包的懸壁接觸持續的連續性和規律性,為礁道形狀的三維地質建模提供了便利。定義礁道界限的線框模型允許常規地質塊體建模和品位估計適用於礁型PGM礦牀,其特徵是礦體和PGM等級的長期連續性(即地質和品位連續性)。鑑於J-M珊瑚礁的局部厚度和等級變異性很大,以及地面和地下定義鑽孔數據支持的區域(最終歸類為測量)和僅由地面數據支持的區域(最終歸類為指示或推斷)之間的數據點密度對比,決定按域為這兩個區域建立單獨的線框模型。僅有地面數據支持的區域的線框模型被延伸到預計將出現珊瑚礁的鄰近未鑽探區域,並終止於採礦區塊邊界、地表地形線框模型或主要地質結構的線框模型(例如,Stillwater礦的Horsaman斷層;圖40和圖41)。利用高分辨率機載激光雷達測量數據模擬的地形線框表面形成了礁道3D模型的上傾極限。


91圖40:在斯蒂爾沃特礦斷層處終止的珊瑚礁通道線框模型插圖92圖41:在東博爾德礦堤壩處終止的珊瑚礁通道線框模型插圖93圖42:斯蒂爾沃特礦的J-M珊瑚礁地質和結構模型94圖43:東博爾德礦的J-M珊瑚礁地質和結構模型


95區塊模擬J-M礁不同的走向、傾角和礦化相,需要根據Stillwater和East Boulder Mines的區域進行地質建模和礦產資源評估。區塊建模是在瓦肯進行的。在LeapFrog中為每個區域生成的珊瑚礁通道線框實體內建立了塊模型。為了在J-M礁平面(即X-Z平面)上進行精確的體積模擬,使用了X、Z和Y方向分別為20英尺x 20英尺x礁道寬度的塊尺寸,X和Z方向的子塊為5英尺x 5英尺。每個塊的第三個維度(Y平面)是珊瑚礁線框實體的水平寬度。所使用的區塊尺寸來自克里金鄰域分析(KNA),該分析表明,對於地面和地下定義鑽孔數據支持的區域,X和Z方向的區塊大小可以在當前數據點間距下使用,範圍從3英尺x 3英尺x 3英尺到25英尺x 25英尺x 3英尺,而不會顯著改變估計的克里金效率和迴歸斜率。克立格效率和迴歸斜率是用來評估估計質量的關鍵指標。KNA的結果還表明,在僅有地面鑽孔數據支持的地區,X和Z方向的區塊尺寸可以增加到200英尺x 200英尺。地面和地下定義鑽孔數據支持的區域的數據點間距從不到25英尺到100英尺,而其餘礦山足跡的間距從100英尺到1000英尺。因此,在今後的評估中,合格人員在評價J-M珊瑚礁時使用了兩個區塊大小,在鑽井較好的區域使用較小的區塊大小,在稀疏鑽探的區域使用較大的區塊大小。等級和噸位估算等級和厚度估算Vulcan的FOZPT、UHW、2E和FCW估算是通過將各自的合成數據直接插入Stillwater和East Boulder Mines每個區域的區塊模型來實現的(表16)。簡單克立格內插法基於三遍搜索,搜索參數彙總於表16,KNA以及表12和表13總結的變分分析結果提供了這些信息。第一次搜索的半徑與變差函數範圍對齊,而第二次搜索的搜索半徑被設置為相關變量和區域的變差函數範圍的1.8倍(Stillwater)和相關變量和區域的變差函數範圍的1.5倍和1.7倍。第三個搜索半徑設置為兩個礦井的相關變量和區域的變異函數範圍的10倍。在估計稀疏數據的下盤地帶時,將靜水礦井的最小樣本數降低到4個。東博爾德礦沒有對下盤地帶的品位進行建模。三遍搜索策略確保FOZPT、UHW和FCW內插到所有塊中,搜索半徑較大時的估計置信度低於第一次搜索。因此,搜索距離和通知估計的樣本數量被包括在礦產資源分類方案中。由於使用簡單的克立格插值法,需要參考平均值來指導插補過程,因此有必要確定FOZPT、2E、UHW和FCW的域平均值。從相關變量的分類封頂數據中計算每個域的全局平均值,並在96個數據挖掘中以10英尺為增量計算不同面板大小(從10英尺到600英尺)。這產生了6000個交互作用,並選擇提供最低平均值的迭代作為相關變量的域平均值。FOZPT,2E,表17列出了用於簡單克里金法的UHW和FCW。表16:用於等級估計的搜索參數搜索參考樣本數描述面積最小最大第一次搜索16 34近距離數據點第二次搜索10 20稀疏數據點第三次搜索10 20非常稀疏數據點表17:根據離羣數據計算的域全局平均值UHW(Ft)FOZPT FCW(Ft)2E(Opt)靜水測量和指示Blitz 4.26 2.93 4.14 0.52 Blitz West 2.46 1.06 2.10 0.30 Dowl 5.492.53 3.73 0.59 DOWU 5.49 2.21 3.65 0.54 OSEE 3.24 3.15 3.13 0.67 OSEW 3.62 3.13 3.29 0.70 OSW3.61 3.45 3.21 0.68 UWE 3.55 2.14 2.76 0.56靜水推論WFE 5.52 2.27 3.54 0.55 wfw 5.52 2.27 3.54 0.55 Blitz 4.26 2.93 4.14 0.52 Blitz West 2.461.06 2.10 0.30下跌5.49 2.53 3.73 0.59 DOWU 5.49 2.21 3.65 0.54 OSEE 3.24 3.15 3.13 0.67 UWE 3.55 2.14 2.76 0.56 2區塊1.43 0.36 1.31 0.15東博爾德6.43 3.18 4.93 0.57博爾德東6.43 3.18 4.93 0.57青蛙塘西6.27 3.014.87 0.57青蛙塘東5.08 2.35 3.94 0.49黃銅猴西5.15 2.28 3.95 0.48黃銅猴東5.15 2.28 3.95 0.48經FOZPT簡單克里格插值後,將2E、UHW和FCW劃分為區塊模型,將FOZPT與FCW按區塊劃分,計算出2E級礦產資源報告等級。直接估計的2E等級被用來檢驗間接估計的2E等級。圖44和圖45描繪了包含Stillwater和East Boulder Mines的區塊模型的建模河道(即未稀釋的)2E級。97圖44:模型航道2E分級和分類98圖45:東巨石礦模擬航道2E等級和分類


99區塊模型驗證合格人員通過將封頂合成數據的2E平均等級與建模的2E平均等級進行比較,驗證了中等至鑽井井區的地質區塊模型,如表18所示。表18:估計和評估切割綜合等級雷區平均2E等級(OPT)模型與複合差值(%)合成數據估計-簡單克里金靜水DOWU 0.651 0.632-2.92 DOWL 0.728 0.702-3.57UWE 0.869 0.770-11.39OSW 1.132 1.060-6.36OSEW 1.049 0.982-6.39OSEE 1.120 1.045-6.70Blitz West 0.787 0.586-25.54Blitz 0.850 0.809-4.82East Boulder FPE 0.611 0.602-1.47FPW 0.636 0.618-2.83比較顯示,封頂複合數據的2E平均值高於所有領域的模型結果,反映了估計方法的總體保守性。這一點在閃電戰、豎井東-東、豎井-東-西、豎井-西部和斯蒂爾沃特礦的上西部-東部地區更為明顯,這些地區的模擬結果比綜合平均2E級低4.82%至25.54%。這是由於適用於數據的等級上限,這是一種保守的措施,限制了本地化的高等級樣本對整體估計的過度影響。本地化的高檔次與舞廳聯繫在一起。生產調整的歷史經驗表明,在Stillwater礦開採過程中,回收的金屬含量比估計的要多。因此,隨着時間的推移,估計參數進行了調整,以使估計的金屬含量與回收的金屬含量保持一致。還通過抽查複合數據和沿鑽孔剖面線顯示的區塊模型等級(條帶分析)驗證了估計,如圖46至圖49和水平圖所示。通過對區塊模型內估計等級的分佈進行抽查,對照橫斷面線和水平圖上未設置上限的綜合數據,合格人員還注意到區塊估計和綜合等級之間的總體一致性。然而,全局均值往往對被歸類為指示或推斷的稀疏鑽探區域的估計產生重大影響,這是簡單克里金插值法的一個屬性。等級上限的影響在非豎井區域很明顯(如圖47),在那裏舞廳和離羣點的發生率很高,建模的等級明顯低於輸入的綜合等級。東巨石礦礦產資源主管人員還表示,青蛙塘東和蛙塘西的2E通道等級總體上保持一致(圖45)。儘管2E等級的潛在低估在Stillwater礦山(井外地區)更為明顯,但合格人士對基礎綜合數據和模型2E等級之間的2E等級的一致性感到滿意。因此,區塊模型構成了礦產資源報告的可信基礎。100圖46:東風閃電平均2E等級圖47:靜水礦山東風平均2E等級(OPT)圖48:東巨石礦蛙塘東平均2E等級(OPT)東巨石礦蛙塘東平均2E等級(OPT)東巨石礦蛙塘西平均2E等級(OPT)東風102噸位估計將11.3英尺3/噸(相當於密度0.088噸/英尺3)的噸位係數應用於區塊模型體積,以推導出靜水和東巨石礦的噸位估計。噸位係數是根據Stillwater和East Boulder Mines自2017年以來積累的可用研發數據(2472個數據點)確定的平均值。合資格人士建議繼續進行研發測定,以擴大研發數據集,從而可以對綜合數據的密度和密度加權進行建模,以進一步提高噸位和品位估計的準確性。Stillwater和East Boulder Mines對指示和推斷地區的噸位估計分別按3.5%和5.6%的地質損失係數折現,以計入未知地質結構可能造成的損失。未知地質損失係數是由定義鑽探區塊的校正數據確定的,方法是將總面積斷層除以鑽探面積區塊的總定義。根據礦山核對數據,合格人士在噸位估算過程中確定了每個區塊的噸位係數(資源區塊係數)。資源區塊係數是指超過等級界限的礁石材料的比例,表示為每個定義的已鑽探地質區塊的礁石總噸位的百分比。已確定的資源區塊係數(表19)應用於指示礦產資源區和沒有定義鑽孔數據的直接測量礦產資源區,以考慮定義鑽探後預期的噸位變化。沒有必要將資源區塊係數應用於定義鑽探區域內測量的礦產資源噸位估計。噸位估計還不包括地表50英尺長的頂柱和採空區周圍的礦柱,同時計入了歷史上開採過的礦山部分的採礦枯竭。表19:資源區塊係數靜水和東巨石礦礦山地質區塊資源區塊係數靜水UG上93.30%道指下89.30%區塊-1上88.60%區塊-1下東區71.90%區塊-1下西區95.10%區塊-2 52.20%區塊-3 61.70%區塊-6 89.60%區塊-7 85.80%區塊-8 86.00%閃電式西區66.40%閃電式82.10%東巨石蛙池東區99.80%青蛙池西區99.90%


103礦產資源分類根據不斷增長的地學知識和信心,將礦產資源歸類為推斷、指示或測量。不確定的主要來源是結構擾動、珊瑚礁變化、採樣、實驗室分析、數據處理和估計誤差。所有礦產資源類別(推斷、指示和測量)的鑽孔數據質量相似,因為使用了通用的採樣、實驗室分析方法和數據處理,並對整個數據庫進行了通用的嚴格驗證,從而能夠識別虛假數據並將其補救或排除在評估數據庫之外。因此,數據質量不是礦物資源分類的一個促成因素。然而,J-M珊瑚礁的局部厚度和等級變化是估計中的一個主要不確定性來源。考慮到J-M礁的長期連續性以及高度的局部厚度和品位變化,鑽石巖芯鑽孔間距和靠近已經或正在開採的區域(已通過地下暴露和礦石加工確認了礁的特徵)是影響合格人員評估在Stillwater和East Boulder礦開採的J-M礁的地球科學知識水平和信心的主要變量。此外,合格人員還考慮了估計的質量--第一次搜索得到的估計最高,第三次搜索得到的估計最低--以及對結構模型的信心。總體而言,分類標準確保地面鑽石鑽孔數據僅足以對所指示或推斷的礦產資源進行評估和分類(取決於鑽孔間距),不能僅根據地面鑽孔數據對已測量的礦產資源進行分類。因此,是否有明確的鑽孔數據以及是否接近已開採或正在開採的區域,是對已測量礦產資源進行分類的關鍵因素。由於高度的局部可變性,厚度和等級存在不確定性,因此,所有地區的等級和噸位估計都受到域全球平均值的影響,而域全局平均值是所使用的簡單克立格插值法的關鍵輸入。合格人士支持使用領域方法,因為這減少了J-M珊瑚礁在所有礦產資源類別(推斷、指示和測量)的高度局部變異性所造成的噸位和品位估計的不確定性。在沒有密集定義鑽孔數據的地區,結構解釋中也存在不確定性,根據影響結構模型可信度的數據間隔,將其歸類為指示或推斷。在定義鑽探之後,小規模的地質結構將變得已知,未知的地質損失被應用於沒有定義鑽孔數據的地區的噸位估計,這些數據被歸類為指示或推斷。合格人員採用以下標準進行礦產資源分類:測量:50英尺鑽臺間距(即,


107利用Sibanye-Stillwater提供的表20中的參數,合格人士初步確定了在East Boulder Mines開採和加工一噸至少0.34奧特的高品位礦石所需的最低2e品位。這種情況不包括低品位(0.05-0.34opt)材料,這些材料不可避免地被開採來訪問高等級材料。這種低品位材料的開採成本已經計入了高品位材料的開採成本。此外,有足夠的吊裝和碾磨能力來處理開採的低品位材料,而不會轉移任何高品位材料。從歷史上看,這種低品位材料與高品位材料一起開採和研磨都是有利可圖的,這些材料一起構成了報告為礦物儲量的礦山礦石(Rom)。利用吊裝和處理低品位材料的增量成本,合格人員確定了指示性的2E最低等級約為0.05奧普特(表20)。由於所有至少0.05 opt的材料等級均在East Boulder礦加工,因此合資格人士認為2E邊際品位0.05 opt適用於礦產資源申報,這與East Boulder礦礦物儲量申報所採用的機械化坡道和填方的邊際品位相匹配。將同樣的品位下限計算邏輯應用於Stillwater礦,得到了高品位礦石開採和加工的指示性最低2e品位為0.51 opt,而在增量成本情景下確定的最低2e品位為0.08 opt。較高的截止品位反映了與當前產量提升相關的運營成本高於East Boulder礦的運營成本。由於工廠產能的限制,Stillwater礦山的磨礦原料在0。因此,適用於高品位礦石開採和加工的2E邊際品位0.20opt被用於Stillwater礦的礦產資源報告;這也是用於礦產儲量報告的邊際品位。然而,計劃於2024年投產的Stillwater礦山的額外磨機產能將消除以往的產能限制,允許提升和碾磨不可避免地通過開採的低品位材料以獲取高品位礦石。因此,Stillwater礦的礦產資源報告為2E截止品位0.11opt是合理的。儘管Stillwater礦的礦產資源報告採用了比East Boulder礦更高的2E邊際品位,但合格人士認為這更合適,因此建議兩個礦以0.05 opt的2E邊際品位報告礦產資源。與Stillwater礦山使用的0.11 opt相比,調整截止品位將更全面地反映J-M礁的礦產資源潛力,後者是由於生產提升階段的高運營成本推動的。礦產資源估計2023年12月31日礦產資源報表截至2023年12月31日止財政年度末,Stillwater和East Boulder礦的礦產資源估計載於表21及表22。表21中的礦產資源估計數報告包括礦產儲量,而表22中的估計數不包括礦產儲量。這些估計是對最小開採寬度為7.5英尺時報告的噸位和品位(參考點)108的現場估計,這適用於Stillwater和East Boulder Mines的主要坡道和充填地下采礦方法。此外,據報告,礦產資源的截止品位為0.11opt(3.44g/t)和0.05opt(1。 各個金屬等級基於在濃縮機處常規收集的顆粒分裂(金屬比)數據,總結於表47中。 沒有報告金屬等效物,因為這些與斯蒂爾沃特和東博爾德礦業無關。 負責Stillwater和East Boulder Mines礦產資源報告和籤核的合格人員分別為Jeff Hughs和Jennifer Evans。Jennifer和Jeff是專業地質學家,在Stillwater和East Boulder Mines的礦產資源估計和報告以及J-M礁開採方面擁有五年以上的經驗。 表21:礦產資源估計,包括截至2023年12月31日的財年末的礦產儲量,基於鈀和鉑價格1500美元/盎司 描述礦產資源,包括礦產儲量帝國類別礦山噸(百萬)鈀(選擇)鉑(選擇)2 E(選擇)2 E含量(Moz)測量靜水30.7 0.38 0.11 0.49 15.1東博爾德18.3 0.28 0.08 0.36 6.6分類/平均49.0 0.35 0.10 0.44 21.7指示斯蒂爾沃特25。7 0.38 0.11 0.49 12.5東博爾德28.4 0.27 0.08 0.35 10.0總計/平均值54.1 0.32 0.09 0.41 22.4測量+指示靜水56.4 0.38 0.11 0.49 27.6東博爾德46.8 0.28 0.08 0.35 16.6細分/平均103.1 0.33 0.09 0.43 44.1推斷靜水64.0 0.27 0.08 0.35 22.4東博爾德61.5 0.27 0.08 0.35 21.3分類/平均值125.5 0.27 0.08 0.35 43.7米制類別礦山噸(百萬)鈀(克/噸)鉑(克/噸)2 E含量(Moz)實測靜水27.8 13.15 3.75 16.90 15.1東博爾德16.6 9.65 2.68 12.33 6.6分類/平均44.5 11.84 3。35 15.19 21.7指示靜水23.3 12.96 3.69 16.65 12.5東博爾德25.8 9.40 2.61 12.01 10.0分類/平均值49.1 11.09 3.12 14.21 22.4測量+指示靜水51.1 13.06 3.72 16.79 27.6東博爾德42.4 9.50 2.64 12.13 16.6細分/平均93.6 11.45 3.23 14.68 44.1推斷靜水58.0 9.35 2.66 12.01 22.4東博爾德55.8 9.29 2.58 11.87 21.3總計/平均113.8 9.32 2.62 11.94 43.7 2 E截止品位斯蒂爾沃特礦-0.11選項(3.77克/噸)2 E截止品位東博爾德礦-0.05select(1.71克/噸)鈀價格-1 500美元/盎司鉑價格-1 500美元/盎司2 E回收靜水礦-91.48% 2 E回收東博爾德礦-90.33%鈀:鉑比靜水礦-3.51:1鈀:鉑比東博爾德礦-3.60:1 109表22:截至2023年12月31日的財年結束時礦產資源估計(不包括礦產儲量),基於鈀和鉑價格1 500美元/盎司 描述礦產資源不包括礦產儲量帝國類別礦山噸(百萬)鈀(選擇)鉑(選擇)2 E(選擇)2 E含量(Moz)測量靜水16.1 0.27 0.08 0.34 5.5東博爾德7.2 0.25 0.07 0.32 2.3總計/平均23.2 0.26 0.07 0.34 7.8指示靜水11.4 0.20 0.06 0.26 3.0東博爾德9.8 0.22 0.06 0.28 2.7分類/平均21.3 0.21 0.06 0.27 5.7測量+指示靜水27.5 0.24 0.07 0.31 8.5東博爾德17.0 0.23 0.06 0.30 5.0分類/平均值44.5 0.24 0.07 0.30 13.5推斷斯蒂爾沃特64.0 0.27 0.08 0.35 22.4東博爾德61.5 0.27 0.08 0.35 21.3分類/平均值125.5 0.27 0.08 0.35 43.7米制類別礦山噸(百萬)鈀(克/噸)鉑(克/噸)2 E(克/噸)2 E含量(Moz)實測靜水14.6 9.15 2.61 11.76 5.5 East Boulder 6.5 8.61 2.39 11.00 2.3分類/平均21.1 8.99 2.54 11.53 7.8指示靜水10.4 6.98 1.99 8.96 3.0東博爾德8.9 7.47 2.07 9.54 2.7細分/平均19.3 7.20 2.03 9.23 5.7測量+指示靜水24.9 8.25 2.35 10.60 8.5東博爾德15.4 7.95 2.21 10.16 5.0分類/平均值40.4 8.13 2.30 10.43 13.5推斷靜水58.0 9.35 2.66 12.01 22.4東博爾德55.8 9.29 2.58 11.87 21.3分類/平均值113.8 9.32 2.62 11.94 43.7 2E邊際品位靜水礦-0.11 opt(3.77g/t)2E邊際品位東巨石礦-0.05 opt(1.71克/噸)PD價格-1 500美元/盎司鉑價-1 500美元/盎司2E回收率靜水礦-91.48%2E回收率東巨石礦-90.33%Pd:PT比靜水礦-3.51:1 Pd:PT比東巨石礦-3.60:1礦產資源對比表23和表24顯示2023年12月31日和2022年12月31日對Stillwater和East Boulder礦的礦產資源估計之間的對賬。這兩個估計都是以相同的邊際品位和最小採礦寬度報告的,並由登記人披露。對賬顯示同比變化,其中正值和負值分別表示與登記人披露的2022年12月31日的數字相比有所增加和減少。對賬顯示,由於兩個報告期之間的採礦枯竭(Stillwater礦70萬噸,East Boulder礦60萬噸)、品位區塊模型更新以及額外定義鑽探導致礦產資源分類邊界發生變化,噸位、品位和2e金屬含量同比變化不大。110表23:2022年12月31日至2023年12月31日礦產資源調節(包括礦產儲量的礦產資源)描述礦產資源的同比變化,包括礦產儲量帝國類別礦山噸(百萬)鈀(OPT)鉑(OPT)2E(OPT)2E(OPT)2E含量(MOZ)測量的靜水2.2 0.04 0.01 0.06 2.7東博爾德(0.1)0.02 0.00 0.02 0.4總計/平均2.1 0.03 0.01 0.04 3.0指示斯蒂爾沃特(0.8)0.05 0.01 0.06 1.2東博爾德(0.7)0.02 0.01 0.03 0.5細分/平均值(1.5)0.03 0.01 0.04 1.7測量+指示靜水1.4 0.05 0.01 0.06 3.9東博爾德(0.8)0.02 0.01 0.02 0.8細分/平均值0.6 0.03 0.01 0.04 4.8推斷斯蒂爾沃特0.1(0.01)(0.00)(0.01)(0.5)東博爾德(0.3)(0.01)(0.00)(0.01)(0.6)細分/平均值(0.2)(0.01)(0.測量的蒸餾水2.0 1.50 0.43 1.92 2.7東博爾德(0.1)0.57 0.16 0.72 0.4小計/平均值1.9 1.20 0.34 1.54 3.0表示靜水(0.7)1.63 0.47 2.10 1.2東面博爾德(0.6)0.67 0.19 0.86 0.5小計/平均(1.3)1.12 0.32 1.44 1.7測量+顯示靜水1.3 1.57 0.45 2.01 3.9東博爾德(0.7)0.63 0.18 0.81 0.8小計/平均0.6 1.17 0.33 1.50 4.8推斷靜水0.1(0.22)(0.06)(0.28)(05)東博爾德(0.3)(0.22)(0.06)(0.28)(0.6)小計/平均(0.2)(0.22)(0.06)(0.28)(1.1)2E邊際品位靜水礦-0.11奧特(3.77克/噸)2E邊際品位東博爾德礦-0.05奧特(1.71克/噸)鉑價格-1 500美元/盎司鉑價格-1 500美元/盎司鉑價格-1 500美元/盎司鉑價格-1 500美元/盎司Oz 2E回收率靜水礦-91.48%2E回收率東巨石礦-90.33%Pd:PT比靜水礦-3.51:1Pd:PT比東巨石礦-3.60:1表24:2022年12月31日至2023年12月31日礦產資源調節(不包括礦產儲量的礦產資源)描述不包括礦產儲量的礦產資源同比變化帝國類別礦山噸(百萬)Pd(Opt)鉑(Opt)2e(Opt)2E含量(Moz)測量的蒸餾水1.5 0.03 0.01 00.03 1.0東博爾德0.5 0.02 0.01 0.03 0.4小計/平均2.0 0.03 0.01 0.03 1.4表示靜水(0.5)0.03 0.01 0.04 0.3東博爾德0.7 0.03 0.01 0.04 0.6小計/平均0.2 0.03 0.01 0.04 0.9測量+顯示靜水1.0 0.03 0.01 0.04 1.3東博爾德1.2 003 0.01 0.04 0.9小計/平均2.2 0.03 0.01 0.04 2.3推斷靜水0.1(0.01)(0.00)(0.01)(0.5)東博爾德(0.3)(0.01)(0.00)(0.01)(0.6)小計/平均(0.2)(0.01)(0.00)(0.01)(1.1)


111描述礦產資源同比變化不含礦產儲量帝國類別礦山噸(百萬)鈀(選擇)鉑(選擇)2 E(選擇)2 E含量(Moz)米制礦山噸(百萬)鈀(g/t)鉑(g/t)2 E(g/t)2 E含量(Moz)實測靜水1.4 0.91 0.26 1.17 1.0東博爾德0.4 0.82 0.23 1.05 0.4總計/平均值1.8 0.88 0.25 1.13 1.4指示靜水(0.5)1.00 0.28 1.28 0.3東博爾德0.7 1.12 0.31 1.43 0.6細分/平均值0.2 1.07 0.30 1.36 0.9測量+指示靜水0.9 1.02 0.29 1.32 1.3東博爾德1.1 0.99 0.28 1.27 0.9細分/平均值2.0 1.01 0.28 1.29 2.3推斷靜水0.1(0.22)(0.06)(0.28)(0.5)東博爾德(0.3)(0.22)(0.06)(0.28)(0.6)細分/平均值(0.2)(0.22)(0.06)(0.28)(1.1)2E截止品位靜水礦-0.11 opt(3.77g/t)2E截止品位東巨石礦-0.05 opt(1.71克/噸)Pd價格-1 500美元/盎司鉑價-1500美元/盎司2E回收靜水礦-91.48%2E回收東巨石礦-90.33%Pd:PT比東巨石礦-3.51:1 Pd:PT比東巨石礦-3.60:1112礦產儲量估算礦產資源儲量轉換方法可供轉換的礦產資源在Stillwater和East Boulder Mines開始規劃過程之前,第一個階段是確定可轉換為礦產儲量的礦產資源--這些是指示和測量的礦產資源。礦產資源模型確定了可轉換的噸位、品位和2E含量。礦產儲量估算方法Stillwater和East Boulder礦的礦產儲量是從商業和LOM規劃過程中準備的,該過程將指示和測量的礦產資源轉換為礦產儲量。根據第12.2節規定的標準對礦產儲量進行分類。轉換考慮了與礦產儲量相關的各個學科的所有調整因素,即採礦方法、採礦和勘測因素、礦石加工和冶金回收、基礎設施工程和設備、市場條件、環境和社會事項以及資本和運營成本(第12至18節)。在申報礦產儲量之前,使用一套合理的經濟參數對所生成的LOM計劃生產計劃進行了經濟可行性測試(第19節)。7)。這是由於由於J-M珊瑚礁的高度微易變性,不同的鑽孔數據點間距導致礦物資源類別之間的置信度不同。已測量礦產資源的時間表和已探明礦產儲量的轉換得益於可用於準確約束厚度、噸位和品位的大量地質信息。然而,指示礦產資源和轉換為可能礦產儲量的時間表依賴於統計數據和從每個區域和採礦區塊的已探明礦產儲量面積推斷出的關鍵指標。對Stillwater礦和East Boulder礦的每個分區的礦產儲量進行了估計。將礦藏資源轉換為礦藏所遵循的方法是1990年制定的,並隨着獲得更多的地質和採礦信息而在多年來根據需要進行調整。該方法考慮了礦場中存在的不同生物礁相和分區,以及分區內的一組參數可用於可靠地預測地面和地下鑽探以進行礦產資源評估的事實。採礦經驗以及礦產儲量估計與實際產量數字之間的協調,證明瞭該方法在估計歷來被報告為礦產儲量的噸位和盎司時的穩健性。LOM計劃和後續生產計劃是利用歷史生產力參數編制的,其中包括:每種採礦方法每名礦工每月的採礦量;每英尺底板開發產生的礦石噸;一次開發生產率,每月前進一英尺;以及二次開發生產率,每月前進一英尺;對礦山規劃和生產數據的歷史分析顯示,需要75%的回收率來協調分段開採採場的爆破噸和移走噸。因此,75%的採收率適用於所有次級開採噸和盎司的礦產儲量。此外,在將指示礦產資源量轉換為可能礦產儲量時,表36所示的可採礦性區塊係數(MBF)被應用於噸位估計。MBF按可採區域內的完全稀釋礦石品位噸位與區塊邊界區域內的全部完全稀釋礦石品位噸位或歷史上從該區塊開採的材料的百分比之比計算。最初,計劃包括所有主要開發項目(下盤側向巷道),以進入所測量的礦產資源區的採場區塊。此後,開發設計和進度安排擴展到指定的礦產資源區,在這些區域,通過利用歷史比率計算主要年開發率。採礦法的時間表取決於下盤通道和必要的鑽石鑽探的完成情況,以便根據品位和噸位勾勒出可停採區的輪廓。此外,排程還取決於磨機的進料要求。 也是在此過程中,根據傾斜度對真實寬度進行了修正,並根據採礦方法和使用的設備類型應用了最小採礦寬度。114對於每個採場區塊,已擬定了一份建議書(業務計劃),其中包括(除其他資料外)一次和二次開發要求、礁石寬度、噸位和預測品位、預期礦石回收率、應用的截止品位、整體採場設計、將採用的採礦方法、通風要求、回填要求開採順序以及人力和採礦設備要求。一旦確定了技術投入,每個採場區塊都要接受經濟測試。這項經濟測試使用了技術和財務參數來確定計劃中的回採作業的經濟可行性。它計入了與礦石開採相關的所有成本,並將總成本與區塊產生的收入進行了平衡。根據這一過程,確定了計劃採場的淨現值。在需要的地方(例如,如果採場沒有達到要求的財務回報),採場進行了優化,以返回最佳的值。LOM生產時間表中的噸位和品位被彙總,以得出礦產儲量噸和品位,其中由定義鑽孔數據支持的已測量礦產資源中安排的噸位和品位被歸類為已證實,而地面鑽孔數據支持的已指示和已測量礦產資源中的噸位和品位被歸類為可能。合格人士可以確認,將測量礦產資源轉換為已探明礦產儲量所遵循的過程是基於歷史表現和對賬,其投入和產出報告的準確度水平為±15%。參考點LOM生產計劃中反映並交付給Stillwater和East Boulder Mines進行處理的選礦廠的合計預定噸位和品位是作為礦產儲量估計報告的噸位和品位估計。因此,磨頭是礦產儲量報告的參考點。截止品位2E礦產儲量報告截止品位對於Stillwater礦為0.20 opt(6.86克/噸),對於East Boulder礦為0.05 opt(1.71克/噸)。個別採場輪廓內所有高於下限品位的稀釋區塊均包括在礦物儲量內。2E截止品位被選為最佳截止品位,以確保珊瑚礁可開採部分的連續性,並在優化淨現值的同時實現目標生產效率。通過使用表20中的參數,合格人士確定了在Stillwater和East Boulder礦開採和加工一噸高品位礦石所需的最低2e品位分別為0.51 opt和0.34 opt。這種方法將開採的低品位材料留在地下,如果有未使用的吊裝和礦石加工廠能力,這將是不合適的。因此,該資質人員還根據吊裝的增量成本確定了2E的下限等級


115和加工過程中不可避免地要開採低品位材料,以獲取高品位礦石。由此確定的最低2E品位分別為0.08 opt和0.05 opt(對於Stillwater和East Boulder Mines)。所使用的金屬價格是鉑和鈀的長期預測價格。第16.4節價格預測的理由。用於計算邊際品位的成本是當前的實際運營成本。由於東Boulder礦的低品位材料(0.05 opt至0.34 opt 2E)與高品位材料(大於0.34 opt 2E)一起被經濟地開採和研磨,因此,合資格人士選擇使用0.05 opt作為在機械化坡道和充填礦區報告礦物儲量的2E截止品位。這與通過考慮吊裝和加工的增量成本以及目前碾磨含有高品位和低品位材料的rom礦石的做法而得出的最低2e品位保持一致。Stillwater礦額外選礦能力的計劃投產使Stillwater礦與East Boulder礦處於類似的位置。然而,Stillwater的運營成本較高,因此需要使用比East Boulder礦更高的2E下限品位。採用與East Boulder相同的邊際品位確定邏輯,合格人士選擇使用0.2 opt作為機械化坡道和充填礦區礦產儲量報告的2E邊際品位。這位合格人士還指出,Stillwater礦仍在提高產量,目前的運營成本超過了穩定狀態的運營成本。因此,未來應審查2E截止品位,同時考慮到隨着產量增加而產生的運營成本,以及現有的提升和礦石處理能力,以便在穩定狀態下處理高品位和低品位材料。礦產儲量分類標準LOM生產計劃中的噸位和品位被彙總,以得出礦產儲量噸和品位。在有明確鑽孔數據的已測量礦產資源區安排的噸位和品位被歸類為探明礦產儲量。在沒有定義鑽孔數據的測量和指示礦產資源量中所列的噸位和品位被歸類為可能的礦產儲量。合資格人士可確認,將測量礦產資源量轉換為已探明礦產儲量所遵循的過程是基於歷史表現和對賬,所報告的投入和產出均在±15%的準確度水平內。隨後利用已探明礦產儲量的統計數據和置信度較低的地質區塊模型,將指示礦產資源量轉換為可能礦產儲量的過程,因此,產出報告的準確度為±25%。圖50和圖51分別顯示了Stillwater礦和East Boulder礦的礦產儲量分類圖。116圖50:斯蒂爾沃特礦儲量分類117圖51:東巨石礦儲量分類118儲量估算2023年12月31日礦產儲量表截至2023年12月31日的斯蒂爾沃特礦和東巨石礦儲量估算見表25。只有LOM計劃中已測量和指示的礦產資源部分已納入礦產儲量。Stillwater和East Boulder Mines的噸位和品位估計以磨頭為參考點,而礦產儲量估計分別報告為0.20 opt(6.86克/噸)和0.05 opt(1.71克/噸)的2E邊際品位。噸位和2E品級指通過LOM生產調度得出的預期rom礦石噸位和品級。個別金屬品級是基於細粒裂解(金屬比率)的應用,這些裂解(金屬比率)在表47中總結,並根據Stillwater和East Boulder選礦廠常規收集的實際數據確定。負責報告和批准Stillwater礦和East Boulder礦礦產儲量的合格人員分別是Annette McFarland和Pat Hansen。合格人員為註冊專業工程師,在估算和報告礦物儲量以及在Stillwater和East Boulder礦開採J-M珊瑚礁方面擁有五年以上的經驗。表25:在截至2023年12月31日的財政年度結束時的礦產儲量估計,基於每盎司1250美元的鈀和鉑價格描述礦產儲量帝國類別礦山噸(百萬)鈀(克/噸)鉑(克/噸)2E(OPT)2E含量(MOZ)已探明的Stillwater 7.5 0.34 0.10 0.44 3.3 East Boulder 4.6 0.25 0.07 0.32 1.5小計/平均值12.1 0.31 0.09 0.39 4.8可能的Stillwater 27.5 0。35 0.10 0.45 12.4東博爾德27.0 0.26 0.07 0.34 9.1小計/平均值54.5 0.31 0.09 0.40 21.5已證實+可能蒸餾水35.0 0.35 0.10 0.45 15.7東博爾德31.6 0.26 0.07 0.33 10.6總計/平均66.6 0.31 0.09 0.40 26.3公制類別礦山噸(百萬)鈀(克/噸)鉑(克/噸)2E(G/t)2E含量(MOZ)已證實靜水6.8 11.73 3.34 15.07 3.3東博爾德4.2 8.62 2.39 11.01 1.5小計/平均10.9 10.55 2.98 13.53 4.8可能靜水25.0 12.07 3.44 15.51 12.4東博爾德24.5 9.05 2.51 11.56 9.1小計/平均49.5 10.57 2.98 13.55 21.5已證實+可能靜水31.7 12.00 3.42 15.41 15.7東博爾德28.7 8.98 2.49 11.48 10.6總計/平均值60.4 10.57 2.98 13.55 26.3 2E截止品位靜水礦-0.20 opt(6.86克/噸)2E截止品位東巨石礦-0.05 opt(1.71克/噸)礦產儲量聲明鉑和鉑價格-1 250美元/盎司截止日期測定鉑價格-1 250美元/盎司截止日期鉑價格-1 250美元/盎司Oz 2E回收率靜水礦-91.48%2E回收率東巨石礦-90.33%Pd:PT比靜水礦-3.51:1


119説明礦產儲量PD:PT比率東Boulder礦-3.60:1礦產儲量對帳表26顯示了2023年12月31日和2022年12月31日對Stillwater礦和East Boulder礦的礦產儲量估計數之間的對賬,該估計值是以相同的截止品位和最小開採寬度報告的,並由登記人披露。這些數字還顯示了與去年同期相比的變化,其中正值和負值分別表示與2022年12月31日的數字相比有所增加和減少。對賬顯示,由於兩個報告期之間的採礦枯竭(Stillwater礦70萬噸和East Boulder礦60萬噸)、區塊模型更新、礦產儲量分類邊界以及在礦山規劃期間用於將礦產資源轉換為礦產儲量的修正係數的修訂,噸位和品位同比變化不大。表26:2022年12月31日至2023年12月31日礦產儲量的同比變化帝國類別礦山噸數(百萬噸)Pd(g/t)鉑(g/t)2e(Opt)2e含量(MOZ)證實靜水0.8 0.01 0.00 0.01 0.01 0.5 East Boulder 0.2(0.02)(0.01)(0.02)(0.0)小計/平均值1.1 0.0000 0.00 0.4可能的斯蒂爾沃特(1.2)0.01 0.00 0.02 0.0東博爾德0.3(0.02)(0.00)(0.02)(0.4)分類/平均值(0.9)(0.00)(0.00)(0.00)(0.4)已證明+可能的斯蒂爾沃特(0.4)0.01 0.00 0.02 0.5東博爾德0.5(0.02)(0.00)(0.02)(0.5)總/平均0.2(0.00)(0.00)(0.00)(0.00)0.0米制類別礦山噸(百萬)鈀(g/t)鉑(g/t)2 E(g/t)2 E含量(Moz)已證明 斯蒂爾沃特0.7 0.37 0.11 0.48 0.5東博爾德0.2(0.67)(0.19)(0.85)(0.0)細分/平均值1.0 0.01 0.01 0.01 0.01 0.01 0.4可能的斯蒂爾沃特(1.1)0.51 0.15 0.66 0.0東博爾德0.3(0.53)(0.15)(0.68)(0.4)總計/平均值(0.8)(0.03)(0.01)(0.04)(0.4)已證明+可能的Stillwater(0.3)0.48 0.14 0.61 0.5 East Boulder 0.5(0.55)(0.15)(0.71)(0.5)總計/平均值0.1(0.03)(0.01)(0.0.02E邊際品位靜水礦-0.20 opt(6.86克/噸)2E邊際品位東巨石礦-0.05 opt(1.71克/噸)礦產儲量聲明PD和PT價格-1 250美元/盎司邊際決定PD價格-1 250美元/盎司邊際決定鉑價-1250美元/盎司2E回收靜水礦-91.48%2E回收率東巨石礦-90.33%PD:PT比率靜水礦-3.51:1 PD:PT比率東巨石礦-3.60:1 120風險評估合格人員已完成本TRS中討論的Sibanye-Stillwater美國PGM業務的高級別半定量風險分析。風險分析旨在確定與修正因素的任何方面相關的風險因素或其任何方面的變化如何對Stillwater和East Boulder礦的礦產儲量估計產生重大影響。對於高級別風險分析,合格人士評估了重大風險,該重大風險被確定為一個問題,合理的投資者很可能會在決定是否購買或出售在Sibanye-Stillwater註冊的證券時予以重視。重大風險也應該有很高的發生機率(可能性)。如果問題不滿足這兩個標準,則根據其發生的影響和發生的可能性,該問題已被確定為低到中等風險。Sibanye-Stillwater在Sibanye-Stillwater美國PGM運營部門有一套風險管理流程,該流程識別風險,評估風險的重要性,並在可能的情況下提供風險緩解措施。合格人員參與LOM計劃和礦產儲量的風險評估。 Sibanye-Stillwater已根據其風險管理協議緩解(而不是消除)這些風險,以降低風險發生時發生的可能性和/或影響(嚴重程度),從而導致剩餘風險重新分類為低至中等風險。 合格人員認為風險管理流程穩健且足以識別應緩解以增強LoM計劃的可執行性的重大風險。根據對緩解後剩餘風險的評估,合資格人士無法確定LOM計劃和礦產儲量存在任何與修正因素相關或因修正因素任何方面的變化而產生的未緩解的重大風險。巖土:Stillwater和East Boulder Mines積累了廣泛的巖土數據庫,制定了適合每個地面控制區的巖土條件的地面分類(地面控制區)和支撐措施。這些措施大大減少了Stillwater和East Boulder礦的重大地面墜落。然而,總有一定程度的剩餘低風險與挖掘失敗有關。兩個礦場的廣泛支持系統和標準足以將任何與巖土相關的風險的潛在影響降至最低。地質水文:Stillwater和East Boulder礦的採礦作業沒有因地下水問題而發生實質性中斷,這兩個礦的上部都相對乾燥。然而,在主要進水口的開發和下降過程中,在Stillwater東段遇到了大量的地下水,但隨着進一步的開發,條件已經顯著改善。儘管地下水流入減少,但地下水在開挖穩定性以及產生的水的管理和處置方面的風險很低。無法執行LOM計劃:儘管Stillwater和East Boulder礦的採礦經驗提高了對礦化的瞭解、建模能力和對修正因素的瞭解,但無法消除估計誤差。礦產儲量估計的主要預期誤差來源包括低估生產成本、生產積累慢於計劃、低估人力需求、監管變化、低估品位和噸位以及未知的地質條件。通過使用大量歷史數據對運營的關鍵要素,即rom礦石產量水平、rom礦石品位和運營成本進行LOM預測,這些因素得到了部分緩解。此外,這些礦場有每天監測採礦作業的系統和人員(短時間間隔控制),以便能夠實施時間幹預,從而糾正對計劃的偏差。計劃外生產成本上升:自2019年至2023年,近幾年來,生產成本沒有出現明顯上升。生產成本主要受每個礦場每年產生的礦石及廢料數量及所採用的採礦方法所影響,而兩個礦場的大部分採場均採用具成本效益的機械化坡道及充填方法。為控制成本上升而採取的持續改進措施包括更多地使用機械化採礦方法從而提高生產率和降低運營成本、優化採礦車隊(減少現役單位)以通過擴大Stillwater礦(Stillwater East部分)的採礦足跡和優化利用East Boulder的現有提升和碾磨能力(Fill The Mill Project)來降低維護成本和增加採礦量。 該業務已開始恢復工作並提高產量,以扭轉COVID-19大流行對生產的不利影響。 功率損失:冬季採礦作業的電力損失(由於大雪和大風)是與採礦基礎設施相關的單一低至中等風險。電力損失很少,可以通過使用備用發電機來緩解。發電機有足夠的容量為通信系統和豎井運輸提供電力,以確保人員能夠安全撤離。尾礦儲存能力不足:Stillwater和East Boulder Mines的尾礦儲存設施有足夠的中期儲存能力(七至十年)。這兩個礦的產量增加都縮短了尾礦存儲能力的壽命。通過提升高程提升尾礦庫容量是一項緩解措施,目前正在尋求建造新的尾礦庫設施的許可。允許建造新的尾礦儲存設施可能需要三到五年的時間。Sibanye-Stillwater意識到審批時間很長,已經完成了必要的技術研究,並提交了啟動許可程序所需的許可申請。在Sibanye-Stillwater獲得建造新的尾礦儲存設施或升級現有尾礦儲存設施的批准之前,這些作業不太可能耗盡尾礦儲存設施的能力。122年金屬價格下跌:鈀和鉑的價格根據全球供需情況波動。對鈀和鉑的需求主要取決於它們在汽油和柴油發動機的自動催化轉化器中的使用。鉑和鈀在氫經濟中的使用預計將成為這些金屬的額外關鍵需求驅動因素。LOM計劃中每盎司鈀和鉑的估計收入根據每個礦山正在開採的部分而有所不同。這為礦場提供了靈活性,可以在價格下跌期間推遲次經濟區的開採。限制進入極端天氣事件造成的作業:冬季的冰凍温度和降雪可能會造成不利的作業條件,儘管來自陡峭山坡的雪崩從未直接影響到礦山的作業。Sibanye-Stillwater的除雪和道路維護已被有效地用於即使在冬季暴風雨中也能保持礦井通道。2022年6月13日,一場500年的洪水在蒙大拿州引發了一場不同尋常的冰雪融化和連續不斷的降雨,摧毀了用於進入斯蒂爾沃特煤礦的部分駭維金屬加工419州。損毀導致礦場出入受限,礦場作業暫時暫停七週。修建了一條臨時道路,以恢復進出礦場的通道,以支持礦場的全面運營,同時對受損部分的駭維金屬加工進行修復,從而在2023年7月恢復了通過駭維金屬加工的通道。合格人士認為,再次發生500年來的最低洪災的可能性很大,這將使持續不斷的降雨和道路破壞造成的洪災成為一種低至中等風險。


123採礦方法簡介Stillwater和East Boulder Mines是使用成熟的採礦方法開採J-M珊瑚礁的成熟企業。進入地下作業所需的大多數永久基礎設施已經建立,並在必要時進行升級,以適應洛姆作業計劃中預期的增產。作為礦產儲量基礎的Stillwater和East Boulder礦的LOM計劃是由Sibanye-Stillwater的合格人員在技術專家的支持下在內部構建的,並利用了根據礦山歷史經驗瞭解的修改因素以及資本和運營成本。因此,用於LOM生產規劃和將已測量礦產資源轉換為已探明礦產儲量的技術投入、修正因素、員工水平、資本和運營成本的準確度在±15%以內,且成本允許高達10%的應急。然而,對於LOM生產計劃和將指示礦產資源轉換為可能礦產儲量,投入和成本的準確性在±15%以內,成本允許高達10%-15%的應急。通過詳細的現金流分析評估了LOM計劃的經濟可行性。本TRS的第13.2.4節討論了採礦回收(採場開採)的因素。採礦設計採礦方法原理J-M珊瑚礁露出在Sibanye-Stillwater採礦主張的28英里走向長度上,但由於珊瑚礁的地形、海拔和厚度,無法通過露天採礦方法對其進行經濟開發。因此,不需要適用於露天採礦的廢物剝離。在Stillwater礦,J-M礁的傾角從40°到90°不等,平均為60°。 東博爾德礦的J-M礁向北傾斜35°至55°(平均50°)。最淺的傾斜(35°)是在6500 Level Footwall Lat側向到達的遠西部地區觀察到的。 Stillwater和East Boulder Mines均採用以下地下采礦方法,適合J-M Reef的可變陡傾和狹窄寬度:使用上向或下向進路的機械化坡道和填充(也稱為切割和填充);和 採用縱向孔空場採礦法進行分段開採,隨後進行回填。 礦山也使用的圈養採礦法已被逐步淘汰。 採礦方法組合是可調的,主要受地質工程考慮以及礦化品位和最大限度減少稀釋的要求驅動。每個礦山內兩種採礦方法的百分比分佈(使用頻率)見表27。機械化坡道和充填採礦法(包括礁上底牀開採)是這兩個礦場的主要採礦方法。機械化的坡道和填充法為分離礦石和廢料提供了最大的選擇性。分段回採深孔採礦法通常用於狹窄的連續礦帶。除空場採礦法外,其他採礦方法均採用優質砂或膏體作為充填材料,膠結石充填體(CRF)和/或其他充填材料的使用有限。124表27:Stillwater礦和East Boulder礦採礦方法使用頻率Stillwater礦East Boulder礦機械化坡道和充填86%83%分段回採深孔露天採礦法14%17%機械化坡道和充填採礦法機械化上坡道和充填採礦法是Stillwater和East Boulder礦山的主要採礦方法,而Stillwater礦11%至20%的採場是通過機械化下坡道和充填採礦法開採的。在礦場實踐的兩種坡道和填方應用程序如圖52所示。機械化上、下坡道和充填採礦法的充填體分別主要是砂(分級粗粒磨尾礦)和膏體;過去,CRF用於有限的應用,但由於物流限制已被逐步淘汰。在地面條件允許的情況下,上手方法是首選方法,因為它更具成本效益。在地基條件不太穩定的地方,採用機械化的下部坡道和回填,也使用更昂貴的膏體回填。根據需要,在膏體填充中使用高達12%的水泥,以提供穩定的頭頂膠凝膏體材料。此外,開發坡度不應超過18%。0平方碼LHD。 圖52:機械化正向和負向斜坡和填充採礦方法分段開採和分段開發在JM礁和懸壁具備能力且礁體連續性良好的情況下,採用分段縱向空場採礦,與其他礦區相比,使用相對較短的“長孔”。這種提取方法如圖53所示。在珊瑚平面上以125 20英尺至50英尺的間隔進行鑽探。在珊瑚礁中打入地下層產生的相當大的噸被計入地下層開發噸;這計入“機械化切割和填充”百分比中。 圖53:分段開採(縱向)長孔空場採礦 在分段開採縱向採礦法中,分段底架採用狹窄的單臂吊運。長孔採用長孔氣動和電動液壓鑽機鑽制。一旦分段推進,就從上分段向下分段鑽孔,並在採場末端在該點的整個礁體寬度上進行爆破。然後,按照子層之間的模式向下鑽出爆破孔,並向開槽凸台的開口空腔進行爆破。在採場的礁石上留有大約80英尺到100英尺間隔的支撐柱,以最大限度地減少懸壁破壞和礦石貧化。破碎的礦石用遙控柴油鏟運機從下面的地下挖掘出來,然後用有軌電車運到最近的礦口。除了次要的面板提取外,還廣泛使用後盾。該過程類似於子級別提取,不同之處在於所有活動都在底部進行,因為頂部沒有訪問權限。表28顯示了根據Stillwater和East Boulder礦的實際數據計算的區域和局部採礦率。這位合格人士指出,表28中的區域開採率很低,因為以前由於在鈀價格較低時使用高截止品位,大塊珊瑚礁未被開採。隨着Stillwater和East Boulder Mines的礦產儲量2E截止品位已分別下調至0.20 opt和0.05 opt,以應對鈀價格上漲和這兩個礦自2017年以來產量的增加,開採比率將會上升。126表28:採場採礦率比例尺採礦方法採礦率(%)靜水煤礦東巨石礦西段東段所有區段局部(採場)機械化坡道和充填90 90 95深孔露天採場60 60 60區域(礦)總計40 40 50水文地質模型靜水礦井基於第7.9節討論的靜水東段和西段的水文地質模型。為了處理和排放礦井水,將礦井兩個部分產生的地下水流入合併在一起。目前,地下流入採用一系列主要位於西側礦井外西區的集水池、溝渠、管道和泵站進行管理。Sibanye-Stillwater考慮了地下水流入的預測,以確保整個水管理系統的設計適當,能夠處理預期的流量,並在礦山流入大幅增加之前建造和運行。此外,Sibanye-Stillwater使用這些預測來確保運營符合允許的排水量限制。Stillwater Minor已經完成了評估、設計和允許處理增加的流量,流量最高可能在每分鐘1600加侖左右,認為伊塔斯卡估計在七年內每分鐘3790加侖,繼續以這一峯值和每分鐘3600加侖之間的速度繼續開採,這一估計被誇大了。此外,伊塔斯卡的估計與斯蒂爾沃特東段的經驗數據不一致,後者表明每分鐘流入900加侖到1500加侖。為協助地下開挖中地下水交叉點的管理,Stillwater Mini已採取以下業務幹預措施:在任何推進的開發結束之前,對探測孔進行鑽探;在可能的情況下,對在漂移推進之前鑽出的探測孔進行水力測試;在開發之前進行有可能與大量地下水交叉的全覆蓋灌漿;如果已確定的盆地表現出明顯不同的地下水條件,根據需要進行額外的監測/測試;在開發新的生產區之前評估定義鑽孔的地下水流入,並在適當情況下將這些鑽孔轉換為用於減壓/降水目的的排水孔;和在可能的情況下將排水孔集中在一起,將排放的水收集到較少的流動點,然後可以監測這些流動點並將其引導到抽水設施,並設置所有排水孔以記錄不同/個別區域的管路壓力和排放(累積流量而不是瞬時流量)。


127合格人員滿意地認為,大多數潛在的地下水來源已在礦山設計中確定並考慮在內,同時已為靜水礦山的地下水管理提出了適當的業務幹預措施。這些設計規定了發展方向或放置頂柱和肋柱,以保護地下挖掘免受草叢中失控的水的影響。該合格人士還指出,必須使用探頭鑽孔進行持續監測,以便及早發現任何潛在的不明水源。東Boulder礦的開採計劃位於活躍的採礦前線附近,由於圍巖滲透率低,這些地區沒有遇到任何地下水問題。此外,這些地區的海拔高於礦井的最低水位(6500水位),目前6500水位是周圍地下水水位的下降點。流入可能與歷史採礦作業所經歷的類似或更低,全礦平均湧水量可能只會隨着與當前LOM計劃中高於歷史產量相關的開發和生產活動的增加而略有增加。在71300地區遇到的一個斷層系統含水,一直在減緩開發工作,已被計入採礦計劃中。在其他嚴重斷層和節理地區,或在採礦距離地表500英尺範圍內遇到與地表渠道有關的沖積系統時,也可能會遇到大量的水。合資格人士信納,East Boulder礦的礦山設計規定了發展方向或放置頂柱和肋柱,以保護地下挖掘免受急流中失控的水的影響。巖土工程模型巖土工程特徵J-M礁及其鄰近的懸壁和下盤由不同的組合組成,包括褐巖、斜長巖、淺色斜長巖和橄欖巖。由於Stillwater礦和East Boulder礦的巖性序列相似,兩個礦的支架設計都採用了通用的方法。J-M珊瑚礁、下盤和掛牆帶內的巖石單元根據從60 Mpa到85 Mpa的範圍被歸類為堅固的巖石單位。在強度較低的區域通常與橄欖石堆積體有關或在鑽芯中發現地質構造時,採礦和支撐設計也會相應地進行調整。Stillwater和East Boulder礦的Q值從1到13表示巖石條件較差到良好,其中一般、良好和較差條件的總面積分別為50%、25%和25%。支撐設計在標準操作程序中描述了主要開發項目的地面支撐要求,其中詳細説明瞭三種主要地面類型的要求,即類型1、類型2和類型3。128類型3的地面類型有兩種變體(類型3和類型3+)。表29提供了地面類型的分類標準,而圖21和圖22(第7.10節)提供了分類標準。3)分別顯示了Stillwater礦和East Boulder礦的地面分類圖。表29:Stillwater和East Boulder礦山地面類型地面類型Q-RMR評級描述最小最大最大類型3+0.1 0.39 23 36非常差或很差帶水存在類型3 0.4 0.99 36 44較差類型2 1 3.99 44 56一般類型1 4 100 56 85通過使用巖土鑽探數據進行評估的良好地面條件將由巖土工程師重新評估,因為導致地面較差的許多變量意味着不太可能採用標準方法。巖土工程師將建議為這些地區提供適當的支持。為評估巖土工程數據而確定的巖體特徵被用來劃定具有相似特徵的巖土工程領域。地面類型域和適用的地面支持要求與其他設計和規劃信息相結合。然後,為《採場建議書》文件中的每個規劃採場確定容易出現異常巖石相關風險的區域。在礁石上使用的地面支撐通常是帶網的模式螺栓,這是摩擦穩定器和樹脂錨杆鋼筋螺栓的組合。由於維持最小開採寬度的要求,不可能用市售的機械化錨杆在典型的採場圍護結構中鑽和安裝錨杆。出於這個原因,螺栓安裝有千斤頂或CMAC支撐鑽機。當採場沿走向撤退時,留有支撐肋柱,以保持綜放深孔採礦法採區的上盤穩定。一般而言,被排除在採礦之外的低品位珊瑚礁區域提供了額外的區域支柱支持。 然後要求內部和外部土木工程師評估土木技術複雜區域。必要時,Stillwater和East Boulder Mines聘請外部顧問提供與地面支持性能、採場性能和設計相關的地質技術監督職能。兩個地雷目前在地面條件和地面支持方面使用觸發行動反應計劃(TARP)。隨着問題資產救助計劃從TARP 1升級到TARP 3,該計劃將升級到組織內部的更高級別進行審查。本弓斜井的支撐設計於2021財年在Stillwater東段完成,採用了Stillwater西段和東Boulder礦採用的主要開發支撐設計。由於在斯蒂爾沃特東段開闢了新的區域,因此有機會評估斯蒂爾沃特煤礦這一部分的實際地面情況。觀測到的3型地面129種情況和變種的頻率比預期更高,現有的巖土數據表明,類型1和2(一般和良好)、類型3(差)和類型3+(非常差條件)的面積分裂分別為50%、25%和25%。由於遇到了第三類和第三類以上的土地類型,必須使用膠結巖石填充或上手坡道充填法,並提供廣泛的支持,這影響了這些地區的開發進度、採礦週期和採礦的經濟性。據報道,在一個採場(5600E 18400)發生了一起與不良地面條件有關的地面墜落事件。因此,在2027財年,在靜水東段建立一家膏體廠(SWE膏體廠)已被列為LOM計劃的優先事項。預計在地面條件較差的地區使用膏體充填將提高採礦和成本效益。LOM計劃已經更新,以最大限度地減少採礦類型3和3+地面類型,並優先安排類型1和2地面類型(5600E和6000E層),直到SWE膏體工廠建成。一支專門的支助小組已經成立,負責在過渡期間開採的有限的3類和3類以上的地面類型。 在前者中,惡劣的條件是由於約5000英尺的覆蓋層(山頂)產生的壓力造成的。該地區的採場主要採用下向斜坡和糊狀物填充法開採,以減輕壓力問題。隨着採礦前線在負擔減輕的地區向西推進,預計壓力會減輕。至於下豎井東部地區,西側以斯蒂爾沃特谷斷層和東側A斷層為界,地表條件較差。歷史上,使用膏狀填充進行支撐和下向斜坡和填充方法允許在該地區進行採礦。 東博爾德礦近年來沒有發生任何重大地面事件或地面保障方法的變化。一般來説,機械化坡道和填充採礦法已被廣泛使用,在對潛在應力進行地質分析後進行分段長孔開採。此外,在東Boulder礦的最西部地區,由於高應力導致的第三類地面條件已從現場評估中得到解釋,因此不使用次水平深孔開採(圖22)。合格人士認為,地面控制標準中規定的當前巖石加固足以在整個LOM中進行採礦,但將在必要時進行審查和更新。合資格人士認為,在Stillwater和East Boulder礦使用了數十年的初步開發和採場的支持設計適合於這兩個礦遇到的周圍巖石條件和使用的採礦方法。礦山有豐富的巖土技術數據(第7.10節),在此基礎上通過詳細工程設計了適當的採場尺寸和支持措施。這些支持設計和作業做法也考慮到了Stillwater礦東段的總體礦場設計。然而,由於斯蒂爾沃特東段的地面條件差的頻率高於預期,因此有必要加快在該地區建立一個膏體廠,以改善該地區的採礦週期和效率以及採礦的經濟性。130蒙大拿州國家土地部向Stillwater和East Boulder Mines發放了地面和地面沉陷控制管理許可證,規定了離地面最小的頂柱尺寸和採場活動的最淺深度。這些許可證規定了一條20英尺至50英尺的合格基巖頂柱,用於在不含水道的地表以下開採,否則應使用200英尺的合格基巖頂柱。 Backfill 13.4.4.1概覽 由粗粒尾礦組成的水力填砂是大多數通過機械化坡道和填充法開採的採場中使用的回填料。然而,水泥尾礦膏僅用於通過機械化下向斜坡和填充方法開採的採場,以便在採用這種方法時為支撐提供足夠的回填料強度。使用尾礦作為回填料對於減少尾礦量也很重要,斯蒂爾沃特礦產生的尾礦材料約有44%至50%,東博爾德礦產生的尾礦材料約有46%至48%被用作回填料。無需採取任何額外步驟來處理任何放回礦山的尾礦。 13.4.4.2Stillwater礦山對於Stillwater西段,來自Stillwater選礦廠除塵迴路的尾礦被泵送到砂廠,在那裏高達60%被用於礦山回填過程(通過使用旋風分離器分離-45微米的材料)。膏體充填廠位於靠近入口的地面上,膏體從這裏通過5150W泵入礦井,然後從那裏分配到需要充填的工作面。該區段還有三個沙廠,其中兩個(即4900級和5000級沙廠)位於靠近入口區的位置,第三個位於5500W級,為上西部礦區提供沙質填充。供應給5500瓦級上砂充填廠的尾礦通過5500級入口的增壓泵和旋風分離器去除細粒(-45微米),然後將粗粒放入存儲筒倉。砂充填體主要通過重力輸送到需要充填的採場,並通過高壓正排量泵輸送到5000高度以上的工作面;應該注意的是,多個高度可以由多個工廠提供服務--5500工廠的重力充填或5000工廠的高壓泵。尾礦中的細粒通過離心泵返回地面,儲存在TSF。為了支持Stillwater East段的機械化上向坡道和充填採礦,5600E砂廠提供了水力砂回填。一條4英寸長的輸砂管從5000W泵安裝到Stillwater東段,作為5400E-10400沙子填充廠的主要給水。 預計該部分的專用膏廠將於2027財年投入使用。


131 13.4.4.3東Boulder礦場的東Boulder礦採場是用從地面上的East Boulder選礦廠運送到位於6500層的地下砂廠的整磨尾礦進行回填的,從那裏用增壓泵將沙粒分配到7200層和8200層的另外兩個砂廠。與Stillwater礦山類似,尾礦原料通過旋風分離器泵送,除去細粒,粗粒放置在六個地下儲存倉中,而細粒通過離心泵返回地面,儲存在尾礦儲存設施(TSF)。用正排量泵將砂充填體分派到需要充填的採場。所有的傾倒水和沖洗水都進入礦井廢水系統,該系統向6450層的主泵站報告。Stillwater礦山運營背景Stillwater礦山成立於1986年,每月從單一區段--Stillwater West區段--生產約60,000噸rom礦石,這些rom礦石在現場選礦廠加工。由於計劃將產量逐步提高到每月約10.6萬噸,因此有必要將礦山擴展到閃電戰地區--斯蒂爾沃特東段。Stillwater東段(即閃電戰項目)的開發始於2011年,當時正在挖掘出入口,迄今一直在進行。2022財年,靜水東段所需的基本建設基礎設施(通道、斜坡道和斜道、通風井)的開發工作已完成。e. 2023財年,斯蒂爾沃特西區豎井頭飾、絞車室和絞車繩索結構性損壞,導致四周內無法進入5000 W以下的生產區域,並在八週內擾亂了礦井在5000 W以下運出巖石的能力)。計劃於2024年恢復產量提升,到2029財年及以後約達到每月約10萬噸(每年120萬噸)的穩定產量水平。 關鍵運營基礎設施斯蒂爾沃特礦包括採礦業務和附屬建築,其中包括濃縮機、車間和倉庫、更衣設施、機頭架、提升機房、糊狀工廠、水處理、儲存設施和辦公室。所有地面基礎設施和TSFs都位於Stillwater礦山運營許可證範圍內,該許可證佔地2450英畝。Stillwater礦山已經開發了一段約9英里長的J-M珊瑚礁,包括Stillwater綜合體東部的Stillwater西段和東段。礦井佈置圖54所示為靜水礦井的地下礦井佈置,這也顯示了最終的礦井輪廓。132利用地質域界線,已將Stillwater西段劃分為三個大礦區,即井外、上西部和下遠西區域。這些區塊劃分如下(圖9):上西部地區的區塊1和區塊2,位於道指5,000點上方;下西部地區的區塊1和2,低於道指區塊的5,000點;區塊3和6,位於井口西部地區;區塊7和8,位於井口東部地區。斯蒂爾沃特東段被劃分為兩個大型礦區,即閃電戰西部和閃電戰。13.5.3.1 Stillwater West段進入Stillwater West段的暗礁是通過一個大約2000英尺的垂直豎井和一套與J-M暗礁走向平行的水平井口和漂流系統,垂直間隔在150英尺至400英尺之間。從靜水河谷西坡和東坡不同海拔5000英尺至5900fTamsl的地面入口挖出了十個主要入口。通過從5000英尺的高度向下傾斜,從J-M珊瑚礁到海拔3800英尺的地方開採礦石,在谷底下方形成了五個主要水平。5000英尺以下的另外五個主要水平主要從豎井和豎井坡道系統進入。 下降系統目前訪問2900、2600、2300、2000、1700和1600級別。 其目標是將這些底部開發項目保持在距離J-M礁約100英尺至150英尺的距離,以便可以在J-M礁上以50英尺的間隔鑽探扇形鑽石鑽孔。底牆鑽孔機最初以200英尺的垂直間距打入,但由於掛牆的傾斜度與斯蒂爾沃特東段相似,因此該間距增加到400英尺,這允許從單個FWLW鑽400英尺的垂直段。豎井系統可進入5000 W以下的工作場所。它充當人員和材料運輸的管道,同時還將破碎的巖石(礦石和廢物)吊到地表。Stillwater西段目前使用其300英尺間隔的支路、六個主坡道和垂直挖掘,以提供人員和設備通道、補給運輸和排水、進氣和排氣通風系統、淤泥運輸、回填工廠通道、粉末存儲和/或緊急出口。下層、側向和主要坡道系統將繼續為生產和正在進行的開發活動提供支持。此外,某些礦層需要作為通風系統的組成部分,作為所需的進氣口和/或排氣口,或作為平行分離器,以保持電氣通風馬力平衡,並滿足礦山安全與健康管理局(MSHA)的規定。MSHA法規還規定了礦井工作面備用(二次)逃生途徑的要求,這些水平也滿足了這一需要。這些水平用作永久的礦山服務通道,並用於公路和鐵路運輸、降水和回填泵送設施。133 13.5.3.2靜水東段靜水東段目前正在開發中,底板橫向水平間距為400英尺。5000E TBM漂移是通往該區段的主要通道,該航道位於JM-Reef以南600英尺處。這是一種專用的運輸-通風驅動,而不是普通的FWL。因此,該驅動器還配備了軌道,並作為主要的收集運輸工具,用火車將礦石和廢物運出礦山。5600E Footwall Drive的開發目前正在進行中,該驅動器位於5000E Footwall Drive上方600英尺的地方。該驅動器提供了對回採礦塊的訪問。在斯蒂爾沃特東段的東部,本博坡道也與5600E Footwall Drive相交,以提供額外的出口通道和通風口。 東博爾德礦運營背景東博爾德礦成立於1997年,於2002年開始生產礦石,每月約55000噸。2016年,東博爾德礦的穩定月度ROM礦石產量水平計劃為每月約65 000噸,此前該水平與填充磨坊項目保持一致,該項目旨在利用東博爾德濃縮廠歷史上未使用的產能。 在2020財年,提高生產水平和利用未使用的工廠產能所需的幾個關鍵要素已經到位。開發了72 740個生產坡道系統,啟動了生產開採。為了滿足現有的蛙塘平坦通道的要求,開發了一個斜面,既是通向地面的通風通道,也是帶有地面遮蔽物的二級出口。2020財年第三季度,Fill the Mill項目完成。月產量從2017財年的約54,000噸增加到2021財年的60,000噸。由於新冠肺炎大流行的限制和相關的運營因素,產量增長勢頭在2022財年逆轉至每月約45000噸,但在2023財年保持在每月47000噸。根據目前的LOM計劃,採礦產量將在2024財年達到修訂後的每月約5.3萬-6.3萬噸的穩定水平,相當於每年約63.1萬-76萬噸。主要運營基礎設施東Boulder礦包括地下采礦作業和地面支持設施,如選礦廠、車間和倉庫、更換設施、水處理、存儲設施、辦公室和TSF。所有地面基礎設施和TSF都位於東Boulder礦運營許可證範圍內,該許可證佔地1000英畝。東Boulder礦山已經開發了一段約5英里長的J-M珊瑚礁,包括靜水綜合體西部的青蛙池塘東段和西段。134礦井佈置圖54顯示了東巨石礦的井下佈置,這也顯示了最終的礦井輪廓。採礦法以機械化上斜充填法為主,輔以有限分段回採深孔採礦法。東Boulder礦的J-M珊瑚礁由兩個通道驅動器進入,每個驅動器3個。從地表進入的隧道在6450fTamsl的高度與珊瑚礁相交。從這個交匯點向東和向西發展了底盤運輸,以打開礦牀的走向範圍。採場由200英尺至400英尺垂直間隔水平的坡道和底板側向漂移進入,距離J-M礁約150英尺至200英尺。轉換為已探明礦產儲量的已測量礦產資源根據這些標題的定義描述了鑽石巖心鑽探,這些標題也用於採場准入和開發。目前的礦場佔地5英里長,垂直範圍為2300英尺。礦山計劃預計9400水平是該礦的最終上行水平。主要的平房運輸水平是6500水平,670坡道系統已經發展到9100水平。除了平坦軌道運輸外,該礦是無軌採礦作業。6500水平底盤運輸橫向延伸標稱21 000英尺,6700水平底盤運輸橫向延伸18 000英尺。樓層通過螺旋坡道連接,珊瑚礁通過橫切進入。2010至2015年間,6500標高的西端進一步向西延伸至Graham Creek地區,以連接Graham Creek垂直隆起。


135圖54:Stillwater和East Boulder礦的總體地下佈局顯示了最終的礦山大綱136礦山的壽命規劃和預算簡介LOM生產計劃表中報告了Stillwater和East Boulder礦的礦產儲量,並對其經濟可行性進行了測試。Stillwater礦將從成熟的Stillwater西段和正在開發的Stillwater East段生產礦石。預計Stillwater礦山將在2029財年達到穩定生產,並在此水平上運營到2054年LOM結束。LOM計劃強調在Stillwater West段的所有區域進行地下初級和基礎設施開發,以獲得更多更高品位的礦化帶並提高生產率。在Stillwater東段引入膏體廠(SWE膏體廠)也是LOM計劃的一個重點領域,因為在地面條件較差的地區使用膏體充填將改善採礦條件和成本效益。東巨石礦將同時生產成熟的高品位蛙塘西段和低品位蛙塘東段的礦石。預計East Boulder礦在2027財年至2068財年將以修訂的穩定生產水平運營,此後將減少LOM剩餘時間(2069財年)的產量。穩定勞動力和開發地面擴建項目(例如TSF擴建)是LOM計劃的戰略重點領域。Stillwater和East Boulder Mines利用了DeswikTM套件的礦山設計和調度軟件。這兩個礦山都使用共同的LOM規劃方法,即根據LOM計劃的預測礦石噸位、廢料噸位和頭品位來安排每個已確定的採礦區。對指示的和測量的礦產資源的調度採用了不同的方法,以得出每個礦場的LOM生產調度。方法上的差異是由於已指示的和已測量的礦產資源的地質可信度不同所致。對於將已測量礦產資源轉換為已探明礦產儲量而言,可用於準確約束厚度、噸位和品位的豐富地質信息,以及技術和成本投入的準確性,使估計的編制精確度達到±15%(可行性研究精確度水平)。對於將指示礦產資源轉換為可能礦產儲量而言,稀少的地質信息限制了對估計的信心。因此,轉換依賴於從每個區域和採礦區塊的已探明礦產儲量面積推斷出的關鍵指標的統計數據。這些指定礦產資源區的礦產儲量定義為出租人水平的精確度在±25%以內(初步可行性研究水平的精確度)。礦山規劃標準Stillwater西段每年進行約40,000英尺的一次和二次開發,而Stillwater東段向東擴展,目前每年開發15,000英尺。目前,Stillwater礦的開採足跡跨越了大約45000英尺的走向長度。表30和表31總結了採場和開發的LOM 137計劃和調度標準。表30:靜水礦山採場規劃參數採礦方法採場參數每月每名礦工總噸數百分比採礦方法混合機械化坡道和充填採礦法323 84%88%分段開採367 100%12%表31:靜水礦區一次開發規劃參數開發參數推進係數每月推進英尺數靜水東0.96 7 266 13靜水東0.96 3 130 18東巨石礦每年進行約20,000英尺的一次和二次開發,以擴大采礦和礦產儲量足跡。採場和開發的LOM計劃和調度標準彙總於表32和表33。在制定LOM時間表時使用的所有數據都是基於自礦山開始以來收集的歷史數據。表32:東巨石礦回採規劃參數採礦方法採礦法採場參數每個礦工每月總噸數百分比採礦方法混合機械化坡道充填567 90%80%分段採掘567 85%0%表33:東巨石礦區初期開發規劃參數發展參數推進係數推進係數月推進英尺數噸/英尺青蛙塘西0.95 1 60 14下蛙塘東0.90 1 60 14下蛙塘東0.90 1 60 14下蛙塘西0 歷史生產數據表明,25%的破碎材料沒有從這些礦區回收。100多個採場的HoverMap和LIDAR掃描數據也證實了這一點。因此,自2005年12月以來,對所有次級開採噸和盎司均採用了75%的回收率。 近年來,Stillwater和East Boulder礦山的地下開採品位有所下降。工廠協調的地下開採和12個月期間礦產儲量數據之間的核對顯示,地下開採量為100%,但品位低於計劃。75%的採礦回收率已應用於分段開採設計品位,報告的噸數為100%,意味着品位降低係數為25%。在East Boulder礦,2021年和2022年的面板設計和Hovermap掃描結果分別顯示,面板設計噸以上的平均稀釋度為13849%和62%。採用25%的品位降低係數來降低礦產儲量品位。技術團隊仍然專注於通過修改爆破實踐來減少這些損失的噸。每個採場區塊的單元尺寸根據橫向間距(300英尺至400英尺)、礁石寬度、經濟(付費)走向長度、肋骨和底柱要求而不同。採場單元尺寸是在礦山設計和調度過程中最終確定的。如圖55所示,典型的機械化坡道和充填採場設計表明,包括底柱在內的總高度為300英尺,總回採長度為2000英尺,最小開採寬度為8英尺。圖55:典型機械化坡道和充填採場設計修正係數13.7.3.1簡介通過LOM設計和調度過程將礦產資源轉換為礦產儲量所採用的技術(採礦和測量)修正係數每年都會進行審查,並由合格人員根據礦山歷史產量調節以及交付給工廠的噸和品位進行適當調整。目前正在礦場實施幾項關鍵改進措施,以完善礦場對礦場的對賬進程,並提高數據的粒度,以便更好地限制修改因素,特別是稀釋和刪除。這些改進包括對從礦山不同區域向地面報告的所有淤泥進行稱重,對所有礦頭進行3D數字測繪,以及在採礦後對所有生產礦頭進行激光雷達掃描。 合格人員批准了為Stillwater和East Boulder Mines制定LoM計劃所採用的修改因素。


139 13.7.3.2將礦產資源轉換為礦產儲量所採用的採礦稀釋稀釋係數是基於每種採礦方法的歷史調整以及對修正係數進行審查的近期研究的結果。在歷史數據的基礎上,引入了貧化係數,即回採過程中添加到礦石中的零品位物料量。例如,在假設2E品位為0opt的情況下,向選礦廠交付的礦石噸增加了15%,比Dow UG High的計劃增加了15%。其結果是,交付給選礦廠的礦石噸增加了15%,但原礦品位較低。表34概述了Stillwater礦山每個分區的機械化坡道充填和分段回採採礦方法的礦產資源轉換為礦產儲量所採用的稀釋係數和方法。鑑於Stillwater和East Boulder Mines以機械化坡道和充填法為主,礦產資源報告的單一最小開採寬度(MMW)為7.5英尺,但在礦山規劃中採用了不同的方法來應用最小開採寬度。不同於用於礦產資源估算的稀釋塊體模型,該模型假定100%通過機械化坡道和填充法進行開採,而是使用原始的未稀釋(水道)塊體模型。對於航道區塊模型,在探明儲量範圍內採用基於逐礁開採方法的最小開採寬度調整方法。最小開採寬度為給定採礦方法和採場位置的礦產儲量的最佳回收設定了一個標準,可用來衡量採礦業績。對於使用2.0立方碼LHD開採的區域,額外的1.5英尺掛牆和下壁稀釋被添加到礦石寬度上,但額外增加了1。 此外,如果礦石寬度加上額外稀釋度小於或等於適用的最小開採寬度,則稀釋寬度將等於最小開採寬度,但如果礦石寬度加上額外稀釋度大於最小開採寬度,則將採用稀釋寬度。 自2020年以來,除了最好的恢復之外,斯蒂爾沃特礦的礦產儲備還進行了額外的稀釋。 這種稀釋是由珊瑚礁領域添加的,目標是使已證實的礦產儲量等級與磨機頭等級保持一致。稀釋度見表34。 表34:斯蒂爾沃特礦領域設備的採礦稀釋因子和稀釋方法/工藝水平寬度(ft)真實寬度(ft)稀釋(%)刪除(%)豎井外西上1.5碼LHD -坡道和填充7.4 6.5 15 16 2碼LHD -坡道和填充8.5 7.5 15 16 4碼LHD -坡道和填充12.0 10.6 15 16 Sub-水平抽取5.1 4.5 15 9豎井西下部1.5yd LHD -坡道和填充7.4 6.5 15 16 2 yd LHD -坡道和填充8.5 7.5 15 16 4 yd LHD -坡道和填充12.0 10.6 15 16次水平抽取5.1 4.5 15 9豎井外東-西1.5 yd LHD -坡道和填充7.4 6.5 15 16 2 yd LHD -坡道和填充8.5 7.5 15 16 4 yd LHD -坡道和填充12.0 10.6 15 16分層提取5.1 4.5 15 9 140領域設備/過程水平寬度(英尺)真實寬度(英尺)稀釋(%)刪除(%)豎井外東-東1.5yd LHD -坡道和填充7.0 7.0 15 16 2 yd LHD -坡道和填充7.5 7.5 15 16 4 yd LHD -坡道和填充12.0 12.0 15 16地下提取5.0 5.0 15 9 Blitz West 1.5 yd LHD -坡道和填充7.2 6.5 15 16 2 yd LHD -坡道和填充8.3 7.5 15 16 4 yd LHD -坡道和填充12.0 10.9 15 16 Sub-水平提取5.0 4.5 15 9閃電戰1.5yd LHD -坡道和填充6.7 6.5 15 16 2 yd LHD -坡道和填充7.8 7.5 15 16 4 yd LHD -坡道和填充12.0 11.6 15 16 Sub-水平提取4.7 4.5 15 9上西區東1.5 yd LHD -坡道和填充7.5 6.0 15 16 2 yd LHD -坡道和填充9.4 7.5 15 16 4 yd LHD -坡道和填充12.0 9.6 15 16 Sub-水平提取5.0 4.0 15 9道指上1.5yd LHD -坡道和填充7.9 5.5 15 16 2 yd LHD -坡道和填充10.8 7.5 15 16 4 yd LHD -坡道和填充12.0 8.3 15 16次級提取5.0 3.5 15 9道瓊斯指數下跌1.5yd LHD -斜坡和填充7.9 5.5 15 16 2YD鏟運機斜坡和充填10.8 7.5 15 16 4碼鏟運機斜坡和充填12.0 8.3 15 16分段開採5.0 3.5 15 9表35列出了東Boulder礦使用的兩種採礦方法的貧化係數和方法。它還顯示了機械化坡道和填方的最小水平寬度以及次水平提取方法。就機械化坡道及充填採礦法而言,在任何一個最小水平寬度上加計有10%的計劃外掛牆及下盤超採(稀釋),而在採用分段採礦法開採的地區則預計不會有計劃外稀釋。表35:東巨石礦區的採礦貧化係數及貧化方法方法最小水平寬度(Ft)真寬度(Ft)貧化(%)刪除(%)青蛙塘東西分段開採6.5 5.0 05機械化坡道及填充物9.8 7.5 10 7 13.7.3.3刪除以計入計劃採礦點與供應選礦廠的地面礦堆之間的損失2E盎司。兩個最常見的刪除來源與留在採場底板上的礦石有關,以及當實際採場形狀偏離計劃形狀時,礁石材料留在原地。最近的礦山生產協調研究得出的結論是,如表34和表35所示,Stillwater礦的分段開採採場金屬盎司損失約為9%,機械坡道和充填採場的金屬盎司損失約為16%,東Boulder礦的分段開採採場損失約為5%,機械坡道和充填採場損失約為7%。這些是應用於Stillwater和East Boulder Mines的所有區塊141的刪除係數。將每年監測刪除情況,並在必要時進行修訂。13.7.3.4低品位礁石材料在Stillwater和East Boulder Mines的常見做法是,當提升和研磨能力過剩時,將低於高品位礦石截止品位的材料運往選礦廠。這種低品位的礁石材料(內部稱為礁砂)被開採以獲取高品位的礁石材料。當有足夠的吊裝和碾磨能力時,將低品位和高品位的礁料一起吊裝和碾磨。在East Boulder礦,主要的機械化坡道和充填採場的2E截止品位為0.05 opt,這使研磨材料的頭部品位和噸位與礦物儲量保持一致;少數次水平開採採場的2E截止品位為0.20 opt。在Stillwater礦,對賬數據表明,低品位材料的平均2e品位為0.12 opt,約佔磨礦噸位的9%。然而,低品位材料被排除在作為Stillwater礦礦物儲量基礎的LOM計劃之外,這是因為在Dow上部和Dow下部區塊模型中使用了較高的2e下限品位0.2 opt,而在該礦其餘部分使用了0.3 opt的下限品位。 13.7.3.5噸位短缺係數靜水礦場的已探明及可能儲備噸位中佔4%的短缺係數。短缺係數指的是未清理掉的遺留在礦牀中的礦石,以及在肋骨中已確定但未開採的礦石。短缺因素減少了礦產儲量中的噸和盎司,但該因素的應用不影響品位。13.7.3.6礦場催繳因素現階段,由於採場與地面礦場儲備之間的盎司損失被歸因於刪除,故沒有將礦場催繳因素應用於礦產儲量。未來Stillwater和East Boulder Mines的礦山對磨對帳將在每個地點建立礦山看漲係數,這些因素將用於礦山規劃。指示礦產資源量與可能礦產儲量的換算係數可採礦性區塊係數(MBF)是估算可能礦產儲量不可或缺的一部分,該係數是在定義鑽探區域中計算的。不同礁域的MBF是從Stillwater和East Boulder Mines的全面礦藏對賬過程中得出的。MBF按可採區域內的完全稀釋礦石品位噸位與區塊邊界區域內的全部完全稀釋礦石品位噸位或歷史上從該區塊開採的材料的百分比之比計算。區塊內的可採區是指已被開採、位於活躍採場內或具有足夠的品位和連續性,應已開採或將被開採的區域。對確定的百分比進行調整,以補償從歷史採場對賬確定的負或正噸位142和金屬盎司餘額。MBF用於在將指示礦產資源轉換為可能礦產儲量時對估計進行調整。表36:Stillwater和East Boulder礦山區塊的可採礦性區塊係數MBF Stillwater Dow UG上方63%道指UG下方58%區塊-1上方71%區塊-1下部32%區塊-1下部70%區塊-2 27%區塊-3 45%區塊-6 53%區塊-7.46%區塊-8 40%Blitz West 25%Blitz 64%East Boulder Frog Pond East 70%Frog Pond West 70%一旦指定礦產資源區的開發和採場設計和佈局確定後,將應用已證明的礦產儲量模型統計數據來推導每個區塊和區域的可開採礦產儲量區域的產量計劃。已證實的礦產儲量模型統計數據如下:產量(以礦石噸/英尺為單位)、產量(以盎司為單位)、品位(以盎司/噸為單位)。區塊及特定領域的統計數據應用於各自的可能礦產儲量區塊,這些區塊有開發設計和高水平採場輪廓,以估計可能礦產儲量噸位和品位。礦山生產調度和預算流程概述Sibanye-Stillwater美國PGM業務遵循正式的LOM生產調度和預算流程,注重業務的綜合性質。Stillwater和Easter Boulder Mines的LOM生產計劃在彙總用於礦產儲量報告之前,已進行了經濟可行性測試。LOM生產調度的重點是一次(橫向)開發設計與調度和採場設計與調度。每個採場都根據一份建議書進行評估,該建議書還包括礁體通道和採場設計、生產計劃和經濟效果。


完成143項評估。只有與積極經濟成果相關的採場才包括在每個礦山的LOM總產量計劃中。開發、採場和LOM生產調度和預算過程中考慮的關鍵因素包括:磨礦天數;rom礦石噸位和2e金屬含量;rom礦石2e品級;低品位礦石(礁砂)精磨噸位;回填位置;採礦方法與噸位和品位的分離;需要一級開發;需要二級開發;開發噸位已破;總噸碎(礦石和廢料);以及待磨削(給礦)的噸位。調度過程產生的數據(噸位、等級和發展)被輸入XERAS系統,用於編製成本預算。預算包括與採礦、加工、工程維護、場地管理費用有關的所有費用,以及與初級開發和礦基項目有關的所有基本建設費用。這些預算隨後在土地管理財務模型中核算,用於對土地管理計劃的經濟可行性進行測試。表37和圖56列出了至2054財年的靜水煤礦LOM生產計劃。圖56顯示了從2026財年到2029財年,與主要是Stillwater East段產量增加相關的產量提升。在2052財年之前,產量將保持在穩定水平,之後,2053財年和2054財年的噸位將有所減少。這一減少是由於目前列入LOM Stillwater礦山生產計劃的已測量和指示的礦產資源耗盡所致。將需要持續的額外定義鑽探,以將部分指示礦產資源升級為包括在生產時間表中的已測量礦產資源,而留在歷史開採區域的未列入計劃的剩餘已測量礦產資源可能會在需要時以微不足道的資本支出納入生產時間表。從2027財年起,隨着礦山接近穩定生產水平和高品位礦石產量與選礦廠產能匹配,2e品位從平均值0.39 opt升至新平均值0.45 opt的10%2e品位也將顯著提高。表37和圖56所反映的品位反映了採用100%礦石百分比的保守方法的影響,以及第13.7.2節討論的將礦產資源轉換為礦產儲量時採用的品位降低係數。144表37:靜水礦山LOM生產計劃圖56:LOM礦石生產計劃根據Stillwater礦山的歷史業績,並考慮到Stillwater礦山現有的採礦設備機隊,合格人士認為LOM生產計劃是可以實現的。LOM生產計劃包括預定的已測量和指示的礦產資源,不包括推斷的礦產資源。表38和圖57顯示了東巨石礦至2069財年的LOM生產計劃。圖57還顯示了在Fill the Mill項目完成後,從2024財年到2068財年計劃的生產目標,達到了2021財年的水平。2069財年減產後停產。加上一些適度的資本支出,表22中反映的未計劃的已測量和指示礦產資源可以納入LOM生產計劃,以便在穩定的2021財年2022 FY2023 FY2024 FY2025 FY2026 FY2027 FY2028 FY2029 FY2030 FY2031 FY2032鋼廠飼料噸898 229 746 956 728 560 782 359 777 777 832 930 205 982 715 1 109 772 1 179 1 200 093 1 199 806 1 200 489飼料2e含量(Oz)399 327 5 838 279 207 303 261 3 303 99 377 459 437 352 787 536 547 856 478 555 299可回收的n2e含量(Oz)346 557 260 239 239 239 733 344 027 344 027 344 327921 454 202 489 309 499 275 515 085 509 492飼料2E級(OPT)0.42 0.39 0.38 0.39 0.39 0.41 0.45 0.45 0.45 0.46 0.47 0.46 FY2033 FY2034 FY2035 FY2036 FY2037 FY2038 FY2039 FY2040 FY2041 FY2042 FY2043 FY2044工廠飼料噸數1 199 978 1 199 360 1 200 990 1 200 231 1 198 986 1 199 549 1 198 752 1 200 051 1 199 820 1 199 820 1 199 545 542 305 897533 829 538 272 540 822 520 645 518 209 537 194 542 267可回收2E含量(盎司)502 245 495 265 499 585 497 625 494 227 488 557 492 074 494 497 475 578 473 200 491 188 496 765飼料2E等級(OPT)0.46 0.45 045 0.45 0.45 0.44 0.45 0.45 0.43 0.45 0.45 FY2045 FY2046 FY2047 FY2048 FY2049 FY2050 FY2051 FY2052 FY2053 FY2054研磨機給料噸1 203 718 1 199 573 1 201 232 1 199 847 1 199 641 1 199 983 1 200 282 1 199 816 1 131 245 475 596飼料2 E含量(盎司)535 329 523 484 527 887 522 492 536 474 531 111 579 876 556 019 588 909 252 021可退回2 E含量(盎司)490 641 478 375 482 421 478 053 491 071 485 967 531 009 508 824 541 383 231 682飼料2 E級(可選)0.44 0.44 0.44 0.45 0.44 0.48 0.46 0.52 0.53參數實際參數預算Bdget 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0 200 000 400 000 600 000 100 000 1 200 000 1 400 000 FY 2 0 2 1 FY2 0 2 2 FY 2 0 2 3 FY 2 0 2 4 FY 2 0 2 5 FY 2 0 2 6 FY 2 0 2 7 FY 2 0 2 8 FY 2 0 2 9 FY 2 0 3 0 FY 2 0 3 1 FY 2 0 3 2 FY 2 0 3 3 FY 2 0 3 4 FY 2 0 3 5 FY 2 0 3 6 FY 2 0 3 7 FY 2 0 3 8 FY 2 0 3 9 FY 2 0 4 0 FY 2 0 4 1 FY 2 0 4 2 FY 2 0 42 0 4 6 FY 2 0 4 7 FY 2 0 4 8 FY 2 0 4 9 FY 2 0 5 0 FY 2 0 5 1 FY 2 0 5 2 FY 2 0 5 3 FY 2 0 5 4 Fe e d 2 E G rad e(O P T)M Ill F e e d d(To N S)Mill Fill Tons Feed 2E Level(OPT)145州級或擴展LOM。此外,持續的額外地下清晰度鑽探將允許推斷礦產資源的升級,並允許在2049財年之後保持穩定水平的生產。表38:東Boulder礦的LOM生產時間表圖57:東Boulder礦的LOM生產時間表鑑於東Boulder礦的未計劃推斷礦產資源量,合理地預期,定義鑽探將允許升級重要的推斷礦產資源,並隨後轉換為礦產儲量。34 0.33 0.33 0。32 0.32 0.34 0.35 0.35 0.35 0.35 0.35 0.35 0.35 0.36 0.34 0.35 0.35財年2038財年2039財年2040財年2041財年2042財年2043財年2044財年2045財年2046財年2047財年2048財年2049財年2050財年2051財年2052財年2052 FY 2053 FY 2054磨坊給料噸683 703 717 100 717 897 723 526 739 637 760 135 747 742 745 203 744 689 730 002 721 627 708 004 639 872 702 868 714 501 688 929 694 608 Feed 2 E含量(盎司)236 277 234 410 230 246 236 669 239 466 240 638 238 341 241 038 238 238 597 233 056 232 147 235 460 213 543 232 196 232 869 232 062 229 963可退回2 E含量(盎司)213 440 211 753 207 992 213 795 216 321 217 380 215 304 217 741 215 536 210 530 209 709 212 702 192 903 209 754 210 362 209 633 207 736飼料2 E級(選擇)0.35 0.33 0.32 0.33 0.32 0.32 0.32 0.32 0.32 0.32 0.32 0.33 0.33 0.33 0.33 0.34 0.33財年2055財年2056財年2057財年2058財年2059財年2060財年2061財年2062財年2063財年2064財年2065財年2066財年2067財年2068財年2069財年研磨機給料噸643 795 675 016 719 184 681 280 698 783 671 549 677 236 674 942 655 452 699 749 721 315 739 214 728 286 747 472 405 497 Feed 2 E含量(盎司)211 934 223 655 238 262 225 976 237 230 235 707 237 206 233 969 232 513 237 949 236 569 237 672 233 959 236 433 134 656可退回2 E含量(盎司)191 450 202 039 215 233 204 135 214 302 212 925 214 280 211 355 210 040 214 951 213 704 214 700 211 346 213 581 121 641飼料2 E級(選擇)0.33 0.33 0.33 0.33 0.33 0.34 0.35 0.35 0.36 0.34 0.33 0.32 0.32 0.32 0.33參數實際預算 預算 預算0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0。55 0 100 000 200 000 300 000 400 000 500 000 600 000 700 000 800 000 FY 2 0 2 1 FY 2 0 2 3 FY 2 0 2 5 FY 2 0 2 7 FY 2 0 2 9 FY 2 0 3 1 FY 2 0 3 3 FY 2 0 3 5 FY 2 0 3 7 FY 2 0 3 9 FY 2 0 4 1 FY 2 0 4 3 FY 2 0 4 5 FY 2 0 4 7 FY 2 0 4 9 FY 2 0 5 1 FY 2 0 5 3 FY 2 0 5 5 FY 2 0 50 6 1 FY 2 0 6 3 FY 2 0 6 5 FY 2 0 6 7 FY 2 0 6 9 FY 2 0 7 1 Fe e d P d+P t G ra d e(O P T)M ill F e e d(To N S)Mill Feed Tons Feed 2e等級(OPT)146 2e等級的一致性(LOM平均2e等級約為0.33 opt),與Stillwater礦山相比,這反映了較小的品位變化。預測的2E負責人評級也與三年實際平均值0.33 opt保持一致。該名合資格人士認為,由於礦場備有采礦設備及人手以滿足增加的開發及回採要求,且於2021財年已達到預測產量水平,故可達到預測產量水平。採礦設備Stillwater礦山的作業是機械化的,使用各種設備,如表39所示。對於Stillwater西段和東段,該礦使用4.0立方碼和6.0立方碼的鏟運機進行基礎設施開發,使用2.0立方碼的鏟運機進行礁石作業,包括珊瑚礁開發和採場礦石清除。目前艦隊的其他關鍵部件包括Face鑽機、螺栓鑽機和自卸卡車。這些還得到許多公用事業單位和運輸單位的進一步支持。合格人士滿意地認為,考慮到採礦區和開發區的地理分隔以及所需的日常生產,斯蒂爾沃特東段有足夠的設備來滿足目前的生產目標。計劃的開發和生產增加以及由此產生的機械化設備需求得到了詳細的資本支出和設備採購時間表的支持,該時間表規定在2022財年至2026財年期間採購採礦設備約1.56億美元。該合格人士認為,已計劃在今後五年內採購足夠的設備,以滿足靜水東段計劃擴大的生產水平。表39:Stillwater西段現有機械化採礦設備數量設備描述現有機組數量機械化錨杆鑽機11台CMAC錨杆鑽機36台工作面鑽機33台起重機械75台自卸卡車24台通用車輛221台拖拉機6臺機車13台總計419採用垂直提升(通過豎井)和有軌電車(通過火車和機車)相結合的方式將礦石和廢物從地下工作面運輸到地面處理設施。目前,Stillwater礦地下產生的礦石有60%是通過豎井提升的,其餘的通過火車運輸。隨着斯蒂爾沃特東段生產水平的提高,鐵路運輸的礦石數量將會增加。


307合格人員的同意和簽字基於內部技術專家/專家的技術支持和建議,這些專家/專家沒有發現與其技術規程和運營有關的數據和信息中的致命缺陷,合格人員認為依靠Sibanye-Stillwater(登記人)提供的關於Sibanye-Stillwater美國PGM業務的信息是合理的。我,Jeff·休斯,是根據1933年美國證券法(SK-1300)S-K條例第1300分款規定的合格人員,負責斯蒂爾沃特和東博爾德礦礦產資源的準備和審批。我在此同意以下事項:西班耶-斯蒂爾沃特公司公開提交和使用自2023年12月31日起生效的西班耶-斯蒂爾沃特美國PGM業務的技術報告摘要;在我負責的技術報告摘要中使用和提及我的名字,包括我作為專家或“合格人士”的地位(由SK-1300定義);使用我在截至2023年12月31日的20-F表格年度報告(20-F表格)中我負責的技術報告摘要的任何摘錄、信息或摘要;以及通過引用將20-F表格中包含的上述項目併入Sibanye-Stillwater提交的任何登記聲明中。茲證明本人已閲讀Sibanye-Stillwater提交的2023年12月31日生效的Sibanye-Stillwater美國PGM業務技術報告摘要,該報告支持披露Stillwater和East Boulder礦的礦產資源和礦產儲量。我證明我已經閲讀了20-F表格,並且它公平、準確地反映了我負責的技術報告摘要中的信息。日期:2024年4月19日/S/傑弗裏·J·休斯合格人員簽名傑弗裏·J·休斯_合格人員全名AIPG CPG-11792_專業註冊第309 I,詹妮弗·埃文斯,我是根據1933年美國證券法(SK-1300)S-K法規第1300分部規定的合格人士,負責準備和批准East Boulder礦的礦產資源。我在此同意以下事項:西班耶-斯蒂爾沃特公司公開提交和使用自2023年12月31日起生效的西班耶-斯蒂爾沃特美國PGM業務的技術報告摘要;在我負責的技術報告摘要中使用和提及我的名字,包括我作為專家或“合格人士”的地位(由SK-1300定義);使用我在截至2023年12月31日的20-F表格年度報告(20-F表格)中我負責的技術報告摘要的任何摘錄、信息或摘要;以及通過引用將20-F表格中包含的上述項目併入Sibanye-Stillwater提交的任何登記聲明中。茲證明本人已閲讀Sibanye-Stillwater提交的2023年12月31日生效的Sibanye-Stillwater美國PGM業務技術報告摘要,該報告支持披露Stillwater和East Boulder礦的礦產資源和礦產儲量。我證明我已經閲讀了20-F表格,並且它公平、準確地反映了我負責的技術報告摘要中的信息。日期:2024年4月19日S/詹妮弗·A·埃文斯_我是根據1933年美國證券法(SK-1300)S-K條例第1300分款規定的合格人員,負責準備和批准靜水礦的礦產儲量。我在此同意以下事項:西班耶-斯蒂爾沃特公司公開提交和使用自2023年12月31日起生效的西班耶-斯蒂爾沃特美國PGM業務的技術報告摘要;在我負責的技術報告摘要中使用和提及我的名字,包括我作為專家或“合格人士”的地位(由SK-1300定義);使用我在截至2023年12月31日的20-F表格年度報告(20-F表格)中我負責的技術報告摘要的任何摘錄、信息或摘要;以及通過引用將20-F表格中包含的上述項目併入Sibanye-Stillwater提交的任何登記聲明中。茲證明本人已閲讀Sibanye-Stillwater提交的2023年12月31日生效的Sibanye-Stillwater美國PGM業務技術報告摘要,該報告支持披露Stillwater和East Boulder礦的礦產資源和礦產儲量。 我證明我已閲讀20-F表格,並且它公平、準確地代表了我負責的技術報告摘要中的信息。 日期:4月19日,2024 /s/ Annette McFarland_合格人員全名採礦專業工程師-第23215號__專業註冊


我是Pat Hansen,根據1933年美國證券法(SK-1300)第1300條規定,Pat Hansen是一名合格的人員,負責準備和批准East Boulder礦的礦產儲量。我在此同意以下事項:西班耶-斯蒂爾沃特公司公開提交和使用自2023年12月31日起生效的西班耶-斯蒂爾沃特美國PGM業務的技術報告摘要;在我負責的技術報告摘要中使用和提及我的名字,包括我作為專家或“合格人士”的地位(由SK-1300定義);使用我在截至2023年12月31日的20-F表格年度報告(20-F表格)中我負責的技術報告摘要的任何摘錄、信息或摘要;以及通過引用將20-F表格中包含的上述項目併入Sibanye-Stillwater提交的任何登記聲明中。茲證明本人已閲讀Sibanye-Stillwater提交的2023年12月31日生效的Sibanye-Stillwater美國PGM業務技術報告摘要,該報告支持披露Stillwater和East Boulder礦的礦產資源和礦產儲量。我還證明,Sibanye-Stillwater美國PGM業務的技術報告摘要公平、準確地反映了我負責的部分中的信息。我證明我已經閲讀了20-F表格,並且它公平、準確地反映了我負責的技術報告摘要中的信息。我在此同意以下事項:西班耶-斯蒂爾沃特公司公開提交和使用自2023年12月31日起生效的西班耶-斯蒂爾沃特美國PGM業務的技術報告摘要;在我負責的技術報告摘要中使用和提及我的名字,包括我作為專家或“合格人士”的地位(由SK-1300定義);使用我在截至2023年12月31日的20-F表格年度報告(20-F表格)中我負責的技術報告摘要的任何摘錄、信息或摘要;以及通過引用將20-F表格中包含的上述項目併入Sibanye-Stillwater提交的任何登記聲明中。茲證明本人已閲讀Sibanye-Stillwater提交的2023年12月31日生效的Sibanye-Stillwater美國PGM業務技術報告摘要,該報告支持披露Stillwater和East Boulder礦的礦產資源和礦產儲量。我還證明,Sibanye-Stillwater美國PGM業務的技術報告摘要公平、準確地反映了我負責的部分中的信息。我證明我已經閲讀了20-F表格,並且它公平、準確地反映了我負責的技術報告摘要中的信息。日期:2024年4月19日/S/馬太D.拉德瓦拉_。我在此同意以下事項:西班耶-斯蒂爾沃特公司公開提交和使用自2023年12月31日起生效的西班耶-斯蒂爾沃特美國PGM業務的技術報告摘要;在我負責的技術報告摘要中使用和提及我的名字,包括我作為專家或“合格人士”的地位(由SK-1300定義);使用我在截至2023年12月31日的20-F表格年度報告(20-F表格)中我負責的技術報告摘要的任何摘錄、信息或摘要;以及通過引用將20-F表格中包含的上述項目併入Sibanye-Stillwater提交的任何登記聲明中。茲證明本人已閲讀Sibanye-Stillwater提交的2023年12月31日生效的Sibanye-Stillwater美國PGM業務技術報告摘要,該報告支持披露Stillwater和East Boulder礦的礦產資源和礦產儲量。我還證明,Sibanye-Stillwater美國PGM業務的技術報告摘要公平、準確地反映了我負責的部分中的信息。我證明我已經閲讀了20-F表格,並且它公平、準確地反映了我負責的技術報告摘要中的信息。日期:2024年4月19日/S/凱文·C.布塔克_。 Butak _專業註冊314參考Blakely,RJ,和Zientek,M.L.,1985.基性巖侵入的磁異常:靜水雜巖。 斯蒂爾沃特綜合體,蒙大拿州礦產和地質局,特別出版物92,2002年重印。 察曼斯克,GK,和Zientek,ML eds. 佈德羅,A.,1999.堆積物的流體通量:蒙大拿州斯蒂爾沃特雜巖的J-M礁和相關巖石,《巖石學雜誌》,第40卷,第755-772頁。 DEQ和USFS,1985年。蒙大拿州環境質量部和美國林務局。最終環境影響報告,斯蒂爾沃特項目,1985年12月。 DEQ和USFS,2012年。最終環境影響聲明,Stillwater礦業公司的水管理計劃和Boe Ranch LDA,2012年5月。 DEQ和USFS,2012年a。斯蒂爾沃特礦業公司修訂後的水管理計劃和蒙大拿州斯蒂爾沃特縣和甜格拉斯縣Boe Ranch LDA的決策記錄(2012年7月)。 DEQ和USFS,2020年。環境評估草案東博爾德礦第6階段尾礦儲存設施擴建項目,2020年5月。 DEQ,2001年。蒙大拿州環境質量部擔保程序手冊。2001. 詹金斯,MC,Mungall,J.E.,Zientek,M.L.,K.布塔克,科森,M.霍利克,賓夕法尼亞州,麥金利,R.,和更低,H.,2022。美國蒙大拿州斯蒂爾沃特綜合體,珊瑚礁包體與其懸壁之間的化學和結構轉換。《巖石學雜誌》,2022,63,PP1-30。Kleinkopf,D.M.,1985。斯蒂爾沃特雜巖地區的區域重磁異常《靜水雜巖》,蒙大拿州礦產地質局,2002年第92期特別出版物,再版。書名/作者聲明://作者聲明://C.麥卡勒姆,I.S.,2002年。靜水雜巖:地質回顧。收錄於:Boudreau,A.E.(編輯)。靜水綜合體,地質和指南。比林斯,2002年7月21日至25日,第九屆國際白金研討會,A1-25。新澤西州佩奇和M.L.齊恩特克,1985年。Stillwater複合體的地質和構造背景。《靜水雜巖》,蒙大拿州礦產地質局,2002年第92期特別出版物,再版。書名/作者聲明://作者聲明://C.斯蒂爾沃特礦業公司,北方平原資源委員會,紅木資源委員會,斯蒂爾沃特保護協會,2014年。《睦鄰協議》。2014年12月8日修訂。齊恩特克,M.L.,查曼斯克,G.K.,和新澤西州歐文,1985。斯蒂爾沃特雜巖的地層和命名。《靜水雜巖》,蒙大拿州礦產地質局,2002年第92期特別出版物,再版。書名/作者聲明://作者聲明://C.


75 Figure 28: Laboratory Standard MF-16 Data Analysis Figure 29: Laboratory Standard MF-18 Data Analysis Figure 30: Laboratory Standard MF-20 Data Analysis 76 Figure 31: Laboratory Standard MF-21 Data Analysis Figure 32: Laboratory Standard MF-22 Data Analysis Figure 33: Laboratory Standard MF-23 Data Analysis Based on the foregoing, the Qualified Persons conclude that the laboratory’s analytical data shows overall acceptable precision and accuracy, and no evidence of overwhelming contamination that would affect the integrity of the data. As a result, the analytical data from the inhouse laboratory is of acceptable integrity and can be relied upon for Mineral Resource estimation. 77 DATA VERIFICATION Data Storage and Database Management All the drillhole data (i.e., collar and downhole survey, lithological, geotechnical, structural, analytical, and mineralisation data) for Stillwater and East Boulder Mines is stored in the Ore QMS database, which is an in-house built database designed to standardise information gathering during drilling. The data is imported electronically from the Core Logger system into the database. Library tables, key fields and codes are the validation tools available in the Ore QMS database utilised for ensuring correct entries. The Ore QMS database is stored on the central IT server where it is backed up and has rigorous controls (e.g., password protection and access restrictions) to ensure security and integrity of the data. The drillhole data stored in the Ore QMS database is exported to Maptek VulcanTM (Vulcan) modelling software environment, which provides additional backup. The Qualified Persons are satisfied with data storage and validation as well as the database management practices, which are all aligned to industry practice. There are sufficient provisions to ensure the security and integrity of the data stored in the Ore QMS database. Database Verification Internally generated surface exploration and underground definition drillhole data is the primary data utilised for geological modelling and Mineral Resource estimation at Stillwater and East Boulder Mines. The Qualified Persons did not perform independent verifications of the data collected. Independent verification would entail inter alia resampling and re-analysis of all or portions of historical samples to confirm the drillhole data in the database spanning decades which is impractical. As such, the Qualified Persons have reviewed the rigorous validations performed during ongoing data collection and processing and were satisfied with the results and conclusions of the validations and the quality of the historical data stored in the database. The data collection and validation procedures employed at the mines have been in used for decades. Surface topography survey data used was sourced from the USGS and this was validated by comparing it with the historical survey data. The high-resolution topographic survey data was found to have better accuracy than historical survey data used for previous Mineral Resource estimations. The validation of drillhole data is a continuous process completed at various stages during data collection, before and after import into the Ore QMS database and during geological modelling and Mineral Resource estimation. As the Qualified Persons are fulltime employees of Sibanye-Stillwater, they either performed or supervised the validation of the drillhole data collected at the mines after which they approved and signed-off the validated data for Mineral Resource estimation. Historical data was validated by previous Qualified Persons during collection and these validations have been confirmed by the current Qualified Persons. The Mineral Resource estimates for both mines are based on the validated drillhole data collected by Sibanye-Stillwater and its predecessors, which is stored in the Ore QMS database. The current drillhole databases for Stillwater and East Boulder Mines contain data relating 51 289 and 11 568 drillholes, respectively. The databases contain 111 535 assays for Stillwater Mine and 84 603 assays for East Boulder Mine. Of these, 50 164 and 33 180 assays were identified as relating to “ore zone” (i.e. Mineral Resource 78 evaluation cut) samples for Stillwater and East Boulder Mines, respectively. After data validation, ore zone composite data pertaining to 50 164 and 10 385 drillholes was used for the 2023 Mineral Resource estimation at Stillwater and East Boulder Mines, respectively. The primary elements of the drillhole data are the following:  Survey data: drillhole collar co-ordinates, azimuth, dip and down hole surveys;  Lithological data: descriptions of rock type, mineralisation, alteration and geological structures; and  Analytical data: chemical analyses for Pd and Pt for each sample of the J-M Reef analysed at the laboratory. In general, the lithological data is acquired through the routine geological logging of drillcores recovered from surface and underground diamond core drilling. The Geologists who log the drillcores are well-trained and familiar with the J-M Reef, footwall and hangingwall stratigraphy and rock types. In addition, they are supervised by appropriately experienced Geologists who review and approve their log sheets. The core logging is performed according to a standard procedure which standardises data gathering and the type of detail required for each drillhole log, with any deviations or anomalous entries flagged by the inbuilt validations tools available in the Ore QMS database system. During core logging, the Geologists also consider existing drillhole information and any deviation from the expected rock types and stratigraphic sequence are investigated further by the Senior Geologists supervising the logging. Analytical data is received electronically from the laboratory and imported electronically into the database, where it is integrated with the relevant lithological and survey data. Prior to finalisation of the import, the analytical data is assessed, accepted for use and stored in the database according to the analytical quality control protocols discussed in Section 8.4. All drillhole survey data is reviewed and signed-off by the Chief Surveyors. Geologists also validate the survey data by comparing it against planned coordinates and through visual checks in the Vulcan software environment. The imports into the Ore QMS database and validations are performed by experienced geological personnel. In the Ore QMS database, the data is validated for missing and incorrect entries through spot checks completed on strip logs (logs of the integrated collar survey, lithological and assay data) and using the inbuilt validation tools. The drillhole database is also periodically checked using a Vulcan program script that automatically checks for missing, overlapping or inverted analytical intervals during data import. Additional validations include comparisons of survey database entries against surveyed 3D models of the footwall lateral drifts to validate that drillhole collar coordinates, azimuth and inclination. Downhole metal profiles for each drillhole are compared against expected profiles for each geological domain and any discrepancies are investigated further and addressed. The Qualified Persons acknowledge the rigorous validation of the extensive drillhole database utilised for Mineral Resource estimation at Stillwater and East Boulder Mines. The data was validated continuously at critical points during collection, in the Ore QMS database and during geological modelling and Mineral Resource estimation. The Qualified Persons either participated in or supervised some of the validations which were performed by suitably trained personnel. The Qualified Persons also


79 approved the use of the validated drillhole data which was signed-off for Mineral Resource estimation. The Qualified Persons confirm that the data validations are consistent with industry practice while the quantity and type of data collected are appropriate for the nature and style of the PGM mineralisation in the J-M Reef. 80 MINERAL PROCESSING AND METALLURGICAL TESTING Metallurgical Testwork and Amenability There has not been any recent relevant metallurgical testwork completed for the Stillwater and East Boulder concentrator plants, smelter and base metal refinery at the Columbus Metallurgical Complex. The Qualified Persons are of the view that the testwork has not been warranted as the Stillwater and East Boulder concentrator plants and the Columbus Metallurgical Complex facilities have all been operational for several decades and have been upgraded and modified over the years to take account of new technology and increased capacity. Section 14 discusses mineral processing in detail and presents process flow diagrams for the various installed plants. These process flow diagrams are based on industry aligned PGM process flows and technology. Detailed flow sheets, mass balances and metallurgical accounting schedules are available for all the operations. The metallurgical and mineralogical characteristics of the ore from the J-M Reef are well-understood and metallurgical recoveries of the ore processing and mineral beneficiation operations are based on detailed historical production data accumulated over many years. As the Stillwater and East Boulder Concentrators and the Columbus Metallurgical Complex facilities have all been operating sustainably, metallurgical amenability predictions for Stillwater and East Boulder Mine ores and associated forecast budget tonnage throughput rates and metallurgical recoveries are based on historical experience and are supported by operational data reviewed (Section 14.1). Ore from the Stillwater East (Blitz) Section has been processed at the Stillwater Concentrator since 2017. Experience from the processing of this ore indicates that the J-M Reef in this section is metallurgically similar to that in the Stillwater West Section and that the ore has not behaved any differently during processing at the Stillwater Concentrator. Deleterious Elements The Qualified Persons are not aware of any reports of deleterious elements in the concentrate produced from the processing of J-M Reef ore at the Stillwater and East Boulder Concentrators. The ores produced from the mines have been successfully processed for several decades and the Qualified Persons consider it reasonable to expect that there will not be any deleterious elements in the unmined parts of the J-M Reef. Neither bulk nor pilot scale testing has been necessary as the processing facilities have all been operational for several decades. 81 MINERAL RESOURCE ESTIMATES Background An extensive drillhole database relating to 50 164 and 10 385 drillholes at Stillwater and East Boulder Mines, respectively, was utilised for 3D geological modelling of the J-M Reef and the Mineral Resource estimation. The 3D geological modelling of the J-M Reef and Mineral Resource estimation, which were performed internally by Sibanye-Stillwater personnel, are based on common estimation process flow and methodology that suit the architecture, mineralisation style and variability of the J-M Reef at the mines. The process flow is well-established and provides for mandatory checks and validations by the Qualified Persons at critical points in the Mineral Resource evaluation process. The Qualified Persons participated in the 3D geological modelling of the J-M Reef and the Mineral Resource estimation for Stillwater and East Boulder Mines and approved the key inputs and outputs at each stage gate as well as the final 3D geological models and estimates reported. The point of reference for the Mineral Resource estimates for Stillwater and East Boulder Mines is an in situ tonnage and grade estimate of the J-M Reef material for which there are reasonable prospects for eventual economic extraction. Furthermore, estimates are completed for the combined Pd and Pt grades (2E) and reef thickness, but co-products or by-products which occur at low abundances were not estimated. There have been no deleterious elements identified in the J-M Reef since the start of the mining and ore processing operations at Stillwater and East Boulder Mines. Accordingly, no deleterious elements were estimated. A consistent estimation and evaluation approach was employed for Mineral Resources eventually classified as either Measured, Indicated or Inferred at both the Stillwater and East Boulder Mines. The approach is aligned to the conventional estimation and evaluation methods employed for other tabular PGM reefs which are characterised by long-range thickness and grade continuity. The Qualified Persons have assumed that the J-M Reef in the unmined areas will show the long-range thickness and grade continuity and overall reef characteristics observed in the mined-out areas. Therefore, long-range thickness and grade continuity has been assumed from drillhole intersections of the J-M Reef with grade interpolation between sample points based on the simple kriging method. As per the evaluation approach for PGM reefs, the key parameters (variables) estimated/evaluated are 2E grade, length accumulation of 2E grade (i.e. product of reef width and 2E grades), volume and density. Details of the evaluation process flow and the estimates reported are discussed in Sections 11.2 to 11.6 of this TRS. The Mineral Resources in this TRS are reported at a minimum mining width and cut-off grade and exclude the J-M Reef mineralisation within the 50ft crown pillar from surface and in structurally disturbed areas (geological loss). 82 Geological Modelling and Interpretation Zone Picking and Evaluation Cut Determination The Main Zone constitutes the well-mineralised economic part of the J-M Reef that is included in the Mineral Resource evaluation cuts termed the reef channel. However, there are localised occurrences of well-mineralised footwall material included in the evaluation cuts. The Main Zone intersections employed for 3D geological modelling are identified and selected by Geologists through a manual process called zone picking. The Geologists use the hangingwall as a reference on the basis that between 80% and 90% of the Main Zone intersections occur near the hangingwall. The balance (10% to 20%) is made up of intersections that are disrupted by mafic intrusions, faults or other geological features and requires additional geological scrutiny and diligence when generating evaluation cuts. Furthermore, there are areas of Stillwater and East Boulder Mines where the mineralisation occurs in footwall rocks that are distinct from the main zone but is of similar 2E grade. The footwall mineralisation tends to be discontinuous. There is also an area of repeated (duplicated) mineralisation at Stillwater Mine as a result of reverse faulting. A common zone picking methodology is followed at both mines. For each drillhole, validated analytical data is integrated with relevant lithological and sample data to generate an integrated log sheet (strip log) employed for zone picking. Zone picking entails scanning the integrated log sheet of a drillhole to identify the hangingwall of the J-M Reef package. From the hangingwall contact, the underlying mineralised zone (Main Zone and mineralised portions of the immediate footwall units) is identified and delineated using a composite 2E grade threshold of 0.20opt. For each drillhole J-M Reef intersection, the selected portions are assigned a unique identifier geology code indicating that these can be included in the evaluation cut dataset. Zone picking also includes the consideration of neighbouring drillholes in a particular drill section and adjacent drill sections to ensure smooth extension of the zone picks between drillholes and drill sections as well as geological consistency in the interpretation. For poorly mineralised reef intersections with 2E grades below 0.20opt, a single sub-ore grade value is flagged at the hangingwall contact. If no analytical data was collected because of the total lack of any sulphide minerals in the drillcore, a 0.5ft blank interval (at East Boulder Mine) or 1ft blank interval (at Stillwater Mine) is input and flagged at the hangingwall contact of the J-M Reef. Such intersections are assigned a 2E grade equivalent to the instrument LDL during modelling. Zone picking on these intersections requires diligence and experience by the Geologists as there are between 10% and 20% of intersections located in the footwall (localised footwall mineralisation), duplicated or disturbed by geological structures (e.g., mafic intrusions and faults) that need to be identified. These mineralised footwall zones and repeated Main Zones are flagged with unique zone identification numbers, which permit separate assessment and modelling of these zones. The Qualified Persons are satisfied with the zone picking method used to discriminate between mineralised and waste zones as this is appropriate for the nature and style of the J-M Reef and ensures consistency in the delineation of reef composites used for geological modelling and estimation. The Qualified Persons noted that the 0.20opt 2E grade threshold employed for the zone picking (reef channel delineation) is conservative as this is higher than the cut-off grades used for Mineral Resource


83 reporting. However, Mineral Resources are reported at the minimum mining width (thickness) which can be wider than the reef channel, which justifies the use of a higher-grade threshold for zone picking. Data Processing and Analysis 11.2.2.1 Compositing Industry practice was followed for evaluation cut (reef channel) data processing and analysis. Subsequent to zone picking and coding, the evaluation cut data for each drillhole comprising collar and downhole survey, stratigraphic, lithological and analytical data for each drillhole was imported into Vulcan and integrated and positioned into the correct three-dimensional (3D) space through an automated process called de-surveying. The integration of the data allowed for the following validations:  Examination of the sample analytical, collar survey, downhole survey and lithological data to ensure that all drillholes had complete data on the key estimation variables;  Examination of the data to check for spatial errors;  Examination of the analytical data to identify out of range and anomalous data; and  Checking of sample intervals to identify overlaps and unexplained gaps between samples. The validated integrated data was composited in Vulcan by geology code and using the drillhole collar survey, azimuth, inclination and analytical data for each zone pick (evaluation cut). This process resulted in new X, Y, and Z collar co-ordinates, single composite values for Pt, Pd and 2E and thickness (true thickness and apparent thickness) for each drillhole Main Zone intersection. The drillhole composite grades were derived through length weighted averaging of the sample grades in the evaluation cuts. The composite data was utilised for geological block modelling as well as grade and thickness estimation. 11.2.2.2 Statistical Analysis and Grade Capping Statistical analysis was performed in Datamine Supervisor software (Supervisor). Prior to statistical analysis, the evaluation cut datasets for Stillwater and East Boulder Mines were reviewed to identify any residual zero values in the grades. The zero values were replaced by the LDL value for 2E (0.0001opt or 3.125ppb) and thickness (0.01ft) to prevent the problem of negative weights in the kriging equation caused by zero grades and thickness. Replacement of the zero values with LDL values (correction) also improves estimation accuracy in low grade areas. The length weighted composites of the evaluation cuts were subjected to statistical analysis initially by mine and by domain at each of Stillwater and East Boulder Mines. The domains for Stillwater and East Boulder Mines Mine are shown in Figure 9 and Figure 10. Due to sparsity of data at Boulder East and West domains were combined with Frog Pond West while Brass Monkey East and West domains were combined with Frog Pond East for the current evaluation. Therefore, estimation parameters for Frog Pond West were applied to the Boulder domains and parameters for Frog Pond East were applied to Brass Monkey blocks. 84 Statistical data analysis of the composite data involved the construction of scatter plots of thickness vs. 2E grade to assess any correlation between them and histogram plots of grade (2E) to determine population distribution characteristics. Scatter plots of undiluted horizontal thickness (UHW) vs. 2E grade generated using the composite data (Figure 34 and Figure 35) indicated no correlation between these variables but it was decided to estimate grades indirectly as grade-thickness accumulations in line with practice in the PGM sector. Figure 34: Scatter plot of Composite UHW vs. 2E Grade for Stillwater Mine R² = 0.0347 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 C o m p o s it e 2 E G ra d e ( o p t) Undiluted Horizontal Width (ft) 85 Figure 35: Scatter plot of Composite UHW vs. 2E Grade for East Boulder Mine Histogram analysis of the 2E data (Figure 36 and Figure 37) revealed positively skewed distributions and outliers (anomalous values). Outliers tend to have undue influence on the overall estimates and, to minimise this influence, the outliers were dealt with using value capping during the estimation runs in Vulcan. Figure 36: Histogram Plot of Composite 2E Grades for Stillwater Mine R² = 0.058 0 1 2 3 4 5 6 0 5 10 15 20 25 30 35 40 45 50 C o m p o si te 2 E G ra d e (o p t) Undiluted Horizontal Thickness (ft) 86 Figure 37: Histogram Plot of Composite 2E Grades for East Boulder Mine Capping was performed on 2E grade and the key variables evaluated, which are reef channel true width in feet (FCW), undiluted horizontal width in feet (UHW) and the grade-thickness accumulation termed feet ounces per ton (FOZPT) which is a product of FCW and 2E grade. Capping values utilised at Stillwater and East Boulder Mines which are presented in Table 11 were selected at the 98th percentile for all areas of Stillwater Mine and Frog Pond East and West at East Boulder Mine to align the modelled grades and actual grades observed at the mines during mining; value capping was set at the 99th percentile for the Brass Monkey and Boulder blocks due to data sparsity. However, the Competent Persons acknowledge the impact of these conservative capping values on masking the actual potential of the reef particularly at Stillwater Mine where the outlier grades are real and often associated with ballrooms. Ballrooms are localised areas of the reef containing anomalous quantities of PGMs and have a significant positive impact on the economics of mining the J-M Reef. Table 11: Capping Grades Employed for the Mineral Resource Evaluation Mine Domain Capping Value UHW (ft) 2E (opt) FOZPT FCW (ft) Stillwater Blitz 24.40 2.67 32.79 23.74 Blitz West 15.90 2.44 17.71 15.01 DOWL 21.30 2.64 15.51 14.44 DOWU 21.60 1.70 11.46 14.46 OSEE 17.80 4.19 31.07 17.05 OSEW 17.00 4.00 26.75 15.22 OSW 18.00 3.93 29.13 15.82 UWE 17.50 3.31 19.34 13.72 BLK2-OSW 22.00 4.85 40.05 19.50 BLK2-UWE 22.40 3.99 26.20 17.30 East Boulder Frog Pond East 19.20 1.56 11.62 14.71 Frog Pond West 19.12 1.53 11.61 14.71 Brass Monkey E&W 19.06 1.51 11.13 14.60 Boulder E&W 18.57 1.57 11.68 14.22


87 11.2.2.3 Geostatistical Analysis The composite FOZPT, UHW and FCW data was also subjected to geostatistical analysis in Supervisor to determine an appropriate estimation methodology and the estimation parameters to be used. The geostatistical analysis included the assessment of spatial trends in the composite 2E, FOZPT, UHW and FCW data for Stillwater and East Boulder Mines. It was observed that these variables exhibit anisotropic behaviour (spatial trends) as depicted in Figure 38 for FCW at Stillwater Mine and Figure 39 for FOZ at East Boulder Mine. Accordingly, normalised variograms were modelled for each the three variables per domain at Stillwater and East Boulder Mines and the variography results for FOZPT, FCW, UHW and 2E, which are relevant to the Mineral Resources, are summarised in Table 12 to Table 15. Figure 38: Spatial Analysis of FCW Continuity for Stillwater Mine Figure 39: Spatial Analysis of FOZ Continuity for East Boulder Mine Table 12: Summary of Standardised Variogram Parameters for FOZPT Mine Domain Nugget Structure 1 Structure 2 Sill 1 Range 1 (ft) Range 2 (ft) Range 3 (ft) Sill 2 Range 1 (ft) Range 2 (ft) Range 3 (ft) Stillwater Blitz 0.36 0.45 159 142 250 0.26 587 327 500 Blitz West 0.44 0.41 173 143 250 0.15 921 760 500 OSWU 0.46 0.43 136 160 250 0.11 1102 886 500 OSWL 0.46 0.43 136 160 250 0.11 1102 886 500 OSEW 0.46 0.48 146 157 250 0.06 1102 762 500 OSEE 0.44 0.38 167 252 250 0.18 887 605 500 UWE 0.47 0.31 142 142 250 0.22 513 368 500 88 Mine Domain Nugget Structure 1 Structure 2 Sill 1 Range 1 (ft) Range 2 (ft) Range 3 (ft) Sill 2 Range 1 (ft) Range 2 (ft) Range 3 (ft) DOWL 0.43 0.34 130 84 250 0.23 490 620 500 DOWU 0.43 0.35 59 94 250 0.22 409 426 500 West Fork E&W 0.43 0.48 245 374 250 0.09 1112 826 500 East Boulder Frog Pond E&W 0.42 0.45 65 95 250 0.13 850 680 500 Brass Monkey E&W 0.42 0.45 65 95 250 0.13 850 680 500 Boulder E&W 0.42 0.45 65 95 250 0.13 850 680 500 Table 13: Summary of Standardised Variogram Parameters for FCW Mine Domain Nugget Structure 1 Structure 2 Sill 1 Range 1 (ft) Range 2 (ft) Range 3 (ft) Sill 2 Range 1 (ft) Range 2 (ft) Range 3 (ft) Stillwater Blitz 0.38 0.44 180 151 250 0.18 806 589 500 Blitz West 0.44 0.41 173 143 250 0.15 921 760 500 OSWU 0.46 0.43 136 160 250 0.11 1102 886 500 OSWL 0.46 0.43 136 160 250 0.11 1102 886 500 OSEW 0.46 0.48 146 157 250 0.06 1102 762 500 OSEE 0.44 0.38 167 252 250 0.18 887 605 500 UWE 0.46 0.38 126 126 250 0.16 803 555 500 DOWL 0.43 0.45 152 110 250 0.12 1086 826 500 DOWU 0.43 0.39 74 104 250 0.18 844 667 500 West Fork E&W 0.43 0.48 245 374 250 0.09 1112 826 500 East Boulder Frog Pond E&W 0.39 0.47 98 95 250 0.14 719 527 500 Brass Monkey E&W 0.39 0.47 98 95 250 0.14 719 527 500 Boulder E&W 0.39 0.47 98 95 250 0.14 719 527 500 Table 14: Summary of Standardised Variogram Parameters for UHW Mine Domain Nugget Structure 1 Structure 2 Sill 1 Range 1 (ft) Range 2 (ft) Range 3 (ft) Sill 2 Range 1 (ft) Range 2 (ft) Range 3 (ft) Stillwater Blitz 0.36 0.45 159 142 250 0.26 587 327 500 Blitz West 0.44 0.41 173 143 250 0.15 921 760 500 OSWU 0.46 0.43 136 160 250 0.11 1102 886 500 OSWL 0.46 0.43 136 160 250 0.11 1102 886 500 OSEW 0.46 0.48 146 157 250 0.06 1102 762 500 OSEE 0.44 0.38 167 252 250 0.18 887 605 500 UWE 0.47 0.31 142 142 250 0.22 513 368 500 DOWL 0.43 0.34 130 84 250 0.23 490 620 500 DOWU 0.43 0.35 59 94 250 0.22 409 426 500 West Fork E&W 0.43 0.48 245 374 250 0.09 1112 826 500 East Boulder Frog Pond E&W 0.39 0.42 88 94 250 0.19 490 322 500 Brass Monkey E&W 0.39 0.42 88 94 250 0.19 490 322 500 Boulder E&W 0.39 0.42 88 94 250 0.19 490 322 500 Table 15: Summary of Standardised Variogram Parameters for 2E Mine Domain Nugget Structure 1 Structure 2 Sill 1 Range 1 (ft) Range 2 (ft) Range 3 (ft) Sill 2 Range 1 (ft) Range 2 (ft) Range 3 (ft) Stillwater Blitz 0.38 0.45 133 200 250 0.17 887 642 500 Blitz West 0.44 0.41 173 143 250 0.15 921 760 500 OSWU 0.46 0.44 109 160 250 0.10 893 876 500 OSWL 0.46 0.44 109 160 250 0.10 893 876 500 OSEW 0.46 0.48 146 157 250 0.06 1102 762 500 OSEE 0.44 0.49 133 153 250 0.07 887 605 500 UWE 0.46 0.39 102 157 250 0.15 826 823 500 DOWL 0.43 0.51 140 106 250 0.06 969 683 500 DOWU 0.43 0.45 92 184 250 0.12 840 806 500 West Fork E&W 0.43 0.51 140 106 250 0.06 969 683 500 Frog Pond E&W 0.44 0.49 192 156 250 0.07 1049 719 500 89 Mine Domain Nugget Structure 1 Structure 2 Sill 1 Range 1 (ft) Range 2 (ft) Range 3 (ft) Sill 2 Range 1 (ft) Range 2 (ft) Range 3 (ft) East Boulder Brass Monkey E&W 0.44 0.49 192 156 250 0.07 1049 719 500 Boulder E&W 0.44 0.49 192 156 250 0.07 1049 719 500 The Qualified Persons are satisfied with the double structured variogram models of FOZPT, FCW, UHW and 2E constructed from the domain composite data as these indicate the achievement of second order stationarity, implying that grade estimation through simple or ordinary kriging interpolation is appropriate. The modelled variograms also indicate moderate nugget to sill ratios which are supported by the available closely spaced data and typical of reef-type PGM deposits. Similarly, the variogram ranges indicated in Table 12 to Table 15 are consistent with reef continuity observed in the mined-out areas while being typical of reef-type PGM deposits. Structural Modelling and Geological Loss Determination The evaluation cuts delineated through zone picking provide an outline of the potentially economic portions of the J-M Reef that can be modelled for reporting as Mineral Resources. Structural interpretation precedes 3D geological modelling of the economic part of the J-M Reef. Most of the major structures delineated at Stillwater and East Boulder Mines were identified from trenching and surface mapping or were interpreted from the available aeromagnetic survey and drillhole data. Ongoing underground mapping and underground definition drilling generates additional closely spaced data used to refine the structural models at both mines. Structural interpretation by the Geologists and the Qualified Persons at both Stillwater and East Boulder Mines identified several major faults and intrusive dykes that intersect, offset or replace the J-M Reef in places. Geological structures of note are the regional South Prairie and Horseman Faults identified at Stillwater Mine. However, there are numerous other medium-scale faults and dykes which were modelled independently in Vulcan and Leapfrog for incorporation in the final 3D geological model. The South Prairie Fault is subparallel to the JM-Reef, intersecting the reef in places or occurring in the hangingwall of the reef causing duplication of the reef in parts of Stillwater Mine such as the Off Shaft West areas. The Horseman Fault is a reverse fault which also offsets the JM-Reef. These faults and the Basal Fault (a “blind” thrust fault) were modelled at Stillwater Mine. The drillhole database contains standardised rock codes for dyke and fault intercepts which are used to construct models for each geological structure. For the current evaluation, fault and dyke outlines were digitised in Vulcan using available data and the geological structure outlines (polylines) were imported into the Leapfrog software environment where wireframes were constructed and projected to the limits of the Mineral Resource footprint. Faults were modelled as planes in the 3D space using both drilling data and geological mapping information for the footwall lateral drifts, where possible. Dykes were modelled as 3D solids. The dyke and fault models were honoured during 3D modelling of the J-M Reef (Figure 40 to Figure 43). As a result, the 3D geological models of the reef already account for explicit geological losses. Additional geological losses were applied to tonnage estimates to account for possible losses due to 90 unknown geological structures. The unknown geological structures (primarily dykes) were estimated from mine reconciliation data collected in the mined-out areas of Stillwater and East Boulder Mines. Unknown geological losses of 3.5% and 5.6% were applied to the tonnages estimates at Stillwater and East Boulder Mines, respectively. The Qualified Persons acknowledge that small-scale faults do not cause geological losses nor necessitate changes in mine designs as these are mined through by underground mining operations. As a result, unknown geological losses due to unidentified small-scale faults were not estimated. However, these faults present geotechnical and grade dilution challenges during mining and are, therefore, accounted for during detailed mine planning. Geological Interpretation and Wireframe Modelling The coded evaluation cut data was imported into Leapfrog for 3D geological block modelling and the data was desurveyed. Geological modelling of the reef channel was based on the “vein system” implicit wireframe modelling tool available in Leapfrog. The 3D geological modelling of the shape of the reef channel was facilitated by the persistent continuity and regularity of the hangingwall contact of the J-M Reef package over most of the geological model footprints at Stillwater and East Boulder Mines. The wireframe models defining the reef channel limits allowed for conventional geological block modelling and grade estimation applicable to reef-type PGM deposits characterised by long range continuity of the orebody and PGM grades (i.e. geological and grade continuity). Given the high intensity of localised thickness and grade variability of the J-M Reef and the data point density contrast between areas supported by both surface and underground definition drillhole data (eventually classified as Measured) and those supported by surface data only (eventually classified as Indicated or Inferred), it was decided to build separate wireframe models for the two areas by domain. Wireframe models for the areas supported by surface data only were extended into adjacent undrilled areas where the reef is expected to occur and terminated at either a mining block boundary, surface topography wireframe model or a wireframe model for a major geological structure (e.g., the Horseman Fault at Stillwater Mine; Figure 40 and Figure 41). A topographic wireframe surface modelled using high- resolution airborne LIDAR survey data forms the up-dip limit of the reef channel 3D model.


91 Figure 40: Illustration of Reef Channel Wireframe Model Terminated at a Fault at Stillwater Mine 92 Figure 41: Illustration of Reef Channel Wireframe Model Terminated at Dykes at East Boulder Mine 93 Figure 42: J-M Reef Geological and Structural Models for Stillwater Mine 94 Figure 43: J-M Reef Geological and Structural Models for East Boulder Mine


95 Block Modelling The varying strike, dip and mineralisation facies of the J-M Reef necessitated geological modelling and Mineral Resource estimation according to the domains at Stillwater and East Boulder Mines. Block modelling was carried out in Vulcan. Block models were built within the reef channel wireframe solids generated for each domain in Leapfrog. Block dimensions of 20ft x 20ft x reef channel width respectively in the X, Z and Y directions were used, with sub-blocking to 5ft x 5ft in the X and Z directions for accurate volume modelling in the plane of the J-M Reef (i.e., X-Z plane). The third dimension (Y plane) of each block is the horizontal width of the reef wireframe solid. Block dimensions used were derived from a Kriging Neighbourhood Analysis (KNA), which indicated that block sizes of ranging from 3ft x 3ft x 3ft to 25ft x 25ft x 3ft in X and Z directions can be used at the current data point spacing for the areas supported by surface and underground definition drillhole data without significantly changing the kriging efficiency and slope of regression of the estimates. Kriging efficiency and slope of regression are key metrics used to assess the quality of estimates. The KNA results also indicate that the block sizes can be increased to 200ft x 200ft in the X and Z directions in areas supported by surface drillhole data only. Data point spacing in the areas supported by surface and underground definition drillhole data ranges from less than 25ft to 100ft whereas the spacing ranges from 100ft to 1 000ft in remainder of the mines' footprints. Accordingly, the Qualified Persons employed a dual block size for the evaluation of the J-M Reef in future evaluations, with a smaller block size used in the well drilled areas and a larger block size used in the sparsely drilled areas. Grade and Tonnage Estimation Grade and Thickness Estimation FOZPT, UHW, 2E and FCW estimation in Vulcan was achieved through simple kriging interpolation of the respective composite data directly into the block models for each domain at both Stillwater and East Boulder Mines (Table 16). The simple kriging interpolation was based on a three-pass search and search parameters are summarised in Table 16 which were informed by the KNA and variography results summarised in Table 12 and Table 13. The radii for the first search were aligned to the variogram ranges whereas the search radii for the second searches were set at 1.8 the variogram range for the relevant variable and domain at Stillwater and 1.5 and 1.7 times the variogram range for the relevant variable and domain at East Boulder Mine. The third search radii set at 10 times the variogram range for the relevant variable and domain at both mines. The minimum number of samples was lowered to four for Stillwater Mine when estimating footwall zones with sparse data. Grades for the footwall zone are not modelled at East Boulder Mine. The three-pass search strategy ensured interpolation of FOZPT, UHW and FCW into all blocks, estimates at longer search radii completed lower levels of confidence than for the first search. Accordingly, search distance and number of samples informing an estimate were included in the Mineral Resource classification scheme. Due to the simple kriging interpolation technique used which requires a reference mean to guide the interpolation process, it was necessary to determine domain mean values for FOZPT, 2E, UHW and FCW. Domain global means were calculated for each domain from declustered capped data for the relevant variable and at different panel sizes ranging from 10ft to 600ft with an increment of 10ft in 96 Datamine. This created 6000 interactions and the iteration that provided the lowest mean value was selected as the domain mean for the relevant variable. The domain global means for FOZPT, 2E, UHW and FCW employed for simple kriging are presented in Table 17. Table 16: Search Parameters Employed for Grade Estimation Search Reference Number of Samples Description of Area Minimum Maximum First Search 16 34 Close spaced data points Second Search 10 20 Sparse data points Third Search 10 20 Very Sparse data points Table 17: Domain Global Means Calculated from Declustered Data Mine Description of Area Domain UHW (ft) FOZPT FCW (ft) 2E (opt) Stillwater Measured and Indicated Blitz 4.26 2.93 4.14 0.52 Blitz West 2.46 1.06 2.10 0.30 DOWL 5.49 2.53 3.73 0.59 DOWU 5.49 2.21 3.65 0.54 OSEE 3.24 3.15 3.13 0.67 OSEW 3.62 3.13 3.29 0.70 OSW 3.61 3.45 3.21 0.68 UWE 3.55 2.14 2.76 0.56 Stillwater Inferred WFE 5.52 2.27 3.54 0.55 WFW 5.52 2.27 3.54 0.55 Blitz 4.26 2.93 4.14 0.52 Blitz West 2.46 1.06 2.10 0.30 DOWL 5.49 2.53 3.73 0.59 DOWU 5.49 2.21 3.65 0.54 OSEE 3.24 3.15 3.13 0.67 UWE 3.55 2.14 2.76 0.56 Block-2 (Surface) 1.43 0.36 1.31 0.15 East Boulder All Areas Boulder West 6.43 3.18 4.93 0.57 Boulder East 6.43 3.18 4.93 0.57 Frog Pond West 6.27 3.01 4.87 0.57 Frog Pond East 5.08 2.35 3.94 0.49 Brass Monkey West 5.15 2.28 3.95 0.48 Brass Monkey East 5.15 2.28 3.95 0.48 After simple kriging interpolation of FOZPT, 2E, UHW and FCW into the block models, 2E grades for Mineral Resource reporting were calculated by dividing the modelled FOZPT with FCW per block. The 2E grades estimated directly were used to check these indirectly estimated 2E grades. Figure 44 and Figure 45 depict the modelled channel (i.e. undiluted) 2E grades contained the block models for Stillwater and East Boulder Mines. 97 Figure 44: Modelled Channel 2E Grades and Classification for Stillwater Mine 98 Figure 45: Modelled Channel 2E Grades and Classification for East Boulder Mine


99 Block Model Validation The Qualified Persons validated the geological block models for the moderately to well drilled domains by comparing 2E mean grades of the capped composite data and the modelled 2E mean grades as shown in Table 18. Table 18: Comparison of the Estimated and Evaluation Cut Composite Grades Mine Domain Mean 2E Grade (opt) Model to Composite Difference (%) Composite Data Estimate - Simple Kriging Stillwater DOWU 0.651 0.632 -2.92 DOWL 0.728 0.702 -3.57 UWE 0.869 0.770 -11.39 OSW 1.132 1.060 -6.36 OSEW 1.049 0.982 -6.39 OSEE 1.120 1.045 -6.70 Blitz West 0.787 0.586 -25.54 Blitz 0.850 0.809 -4.82 East Boulder FPE 0.611 0.602 -1.47 FPW 0.636 0.618 -2.83 The comparisons revealed that the 2E means of capped composite data are higher than those for the model results for all domains reflecting an overall conservativeness in the estimation approach. This is more apparent in the Blitz, Blitz West, Off Shaft-East-East, Off Shaft-East-West, Off Shaft-West and Upper West-East at Stillwater Mine where the modelled results were 4.82% to 25.54% lower than the composite mean 2E grades. This is due to the grade capping applied to the data which is a conservative measure that limits the undue influence of localised high-grade samples on the overall estimates. The localised high grades are associated with ballrooms. Historical experience from production reconciliation indicated that more metal contents than estimated were recovered during mining at Stillwater Mine. As a result, the estimation parameters have been adjusted over time to align the estimated and recovered metal contents. The estimates were also validated through spot checks of composite data and block model grades displayed along drillhole section lines (swath analysis) as depicted in Figure 46 to Figure 49 and on level plans. From the spot checks of the distribution of estimated grades within the block models against uncapped composite data along section lines and on level plans, the Qualified Persons also noted overall alignment between the block estimates and composite grades. However, global means tend to have significant influence in the estimates for sparsely drilled areas categorised as Indicated or Inferred which is an attribute of the simple kriging interpolation method. The impact of grade capping was noticeable in the Off Shaft areas (e.g. Figure 47), where there is a high occurrence of ballrooms and outlier grades and the modelled grades are significantly lower than input composite grades. The East Boulder Mine Competent Person for Mineral Resources also overall consistency in channel 2E grade for the Frog Pond East and Frog Pond West (Figure 45). Despite the potential understating of 2E grades which is more pronounced at Stillwater Mine (Off Shaft areas), the Qualified Persons are satisfied with the congruency in 2E grades between the base composite data and the modelled 2E grades. Accordingly, the block models constitute a credible basis for Mineral Resource reporting. 100 Figure 46: Stillwater Mine Blitz Mean 2E Grade (opt) by Easting Figure 47: Stillwater Mine OSWU Mean 2E Grade (opt) by Easting 101 Figure 48: East Boulder Mine Frog Pond East Mean 2E Grade (opt) by Easting Figure 49: East Boulder Mine Frog Pond West Mean 2E Grade (opt) by Easting 102 Tonnage Estimation A tonnage factor of 11.3ft3/ton (equivalent to a density of 0.088 ton/ft3) was applied to the block model volumes to derive tonnage estimates for Stillwater and East Boulder Mines. The tonnage factor is an average determined from the available RD data (2 472 data points) accumulated since 2017 at both Stillwater and East Boulder Mines. The Qualified Persons recommend continued RD determinations to expand the RD dataset which would permit the modelling of density and density weighting of the composite data to further improve the accuracy of the tonnage and grade estimates. The tonnage estimates for Stillwater and East Boulder Mines for the Indicated and Inferred areas were discounted by the application of geological loss factors of 3.5% and 5.6%, respectively, to account for possible losses due to unknown geological structures. The unknown geological loss factors were determined from reconciliation data in the definition drilled blocks by dividing the total area faults by the total definition drilled of the area blocks. From mine reconciliation data, the Qualified Persons determined a tonnage factor per block (Resource Block Factor) during tonnage estimation. The Resource Block Factor is the proportion of reef material above grade cut-off expressed as a percentage of the total reef tonnage per definition drilled geological block. The Resource Block Factors determined (Table 19) were applied to the Indicated Mineral Resource areas and the immediate Measured Mineral Resource areas with no definition drillhole data to account for the tonnage change expected after definition drilling. It was not necessary to apply the Resource Block Factors to Measured Mineral Resource tonnage estimates within the definition drilled area. The tonnage estimates also exclude the 50ft crown pillar from surface and pillars around mined out stopes while accounting for mining depletion in the historically mined out portions of the mines. Table 19: Resource Block Factors for Stillwater and East Boulder Mines Mine Geological Block Resource Block Factors Stillwater Dow UG Upper 93.30% Dow UG Lower 89.30% Block-1 Upper 88.60% Block-1 Lower East 71.90% Block-1 Lower West 95.10% Block-2 52.20% Block-3 61.70% Block-6 89.60% Block-7 85.80% Block-8 86.00% Blitz West 66.40% Blitz 82.10% East Boulder Frog Pond East 99.80% Frog Pond West 99.90%


103 Mineral Resource Classification Mineral Resources were classified as Inferred, Indicated or Measured depending on increasing levels of geoscientific knowledge and confidence. The main sources of uncertainty are structural disturbance, reef variability, sampling, laboratory analysis, data processing and estimation error. Drillhole data quality is similar across all Mineral Resource classes (Inferred, Indicated and Measured) as common sampling, laboratory analytical methodologies and data processing have been used and the entire database was subjected to common rigorous validations, which enabled the identification of spurious data and its remediation or exclusion from the evaluation database. Therefore, data quality was not a contributing factor in the classification of the Mineral Resources. However, the localised thickness and grade variability of the J-M Reef is a major source of uncertainty in the estimates. Considering the long-range continuity and the high localised thickness and grade variability of the J-M Reef, diamond core drillhole spacing and proximity to areas that have been or are being mined (where reef characteristics have been confirmed from underground exposures and ore processing) were the main variables influencing the Qualified Persons' assessment of level of geoscientific knowledge and confidence in the J-M Reef mined at Stillwater and East Boulder Mines. Furthermore, the Qualified Person also considered the quality of estimates, which is highest for the estimates obtained by the first search and lowest for the estimates obtained by the third search, and confidence in the structural model. In general, the classification criteria ensured that surface diamond drillhole data is only sufficient for the assessment and classification of Mineral Resources as either Indicated or Inferred (depending on drillhole spacing) and that no Measured Mineral Resources were classified based on surface drillhole data only. Therefore, the availability of definition drillhole data and proximity to areas that have been or are being mined were key factors in the classification of Measured Mineral Resources. There are uncertainties in the thickness and grades due to high localised variability and, as a result, grade and tonnage estimates for all areas were influenced by the domain global means which were key inputs to the simple kriging interpolation method used. The Qualified Persons support the use of domain means as these reduce the uncertainty in the tonnage and grade estimates caused by the high localised variability of the J-M Reef across all Mineral Resource categories (Inferred, Indicated and Measured). There are also uncertainties in the structural interpretation in areas that do not have closely spaced definition drillhole data, which are classified as either Indicated or Inferred depending on data spacing which affects the confidence in the structural model. Small-scale geological structures will become known after definition drilling and an unknown geological loss is applied to tonnage estimates in areas with no definition drillhole data, which are classified as Indicated or Inferred. The Qualified Persons employed the following criteria for the Mineral Resource classification:  Measured: The 50ft drill station spacing (i.e.,


107 Using the parameters in Table 20 provided by Sibanye-Stillwater, the Qualified Person initially determined the minimum 2E grades required to pay for the extraction and processing of a ton of high-grade ore at East Boulder Mines of at least 0.34opt. This scenario excludes low-grade (0.05-0.34opt) material which is inevitably mined to access the high-grade material. The cost of mining of this low-grade material is already accounted for in the mining cost for high-grade material. Furthermore, there is sufficient hoisting and milling capacity for the processing of the mined low-grade material without displacing any high- grade material. Historically, this low-grade material has been mined and milled profitably together with the high-grade material and together these materials constitute the run of mine ore (RoM) reported as Mineral Reserves. Using the incremental cost of hoisting and processing the low-grade material, the Qualified Person determined an indicative 2E minimum grade of approximately 0.05opt (Table 20). Since all the material grading at least 0.05opt is processed at East Boulder Mine, the Qualified Person considered a 2E cut-off grade of 0.05opt to be appropriate for Mineral Resource reporting and this matches the cut-off grade for mechanised ramp and fill employed for Mineral Reserve reporting at East Boulder Mine. Applying the same grade cut-off calculation logic to Stillwater Mine, an indicative minimum 2E grade of 0.51opt was obtained for the mining and processing of high-grade ore while a minimum 2E grade of 0.08opt was determined under the incremental cost scenario. The higher cut-off grades reflect the higher operating costs associated with the current production ramp-up than those for East Boulder Mine. Due plant capacity constraints, Stillwater Mine milled material above 0.20opt and the mined low-grade material was not hoisted to surface. Accordingly, the 2E cut-off grade of 0.20opt which was applicable for the mining and processing of high-grade ore was used for Mineral Resource reporting at Stillwater Mine; this was also the cut-off grade used for Mineral Reserve reporting. However, the planned commissioning of additional mill capacity at Stillwater Mine in 2024 will remove the historical capacity constraints allowing for the hoisting and milling of low-grade material inevitably mined through to access high-grade ore. Accordingly, the reporting of Mineral Resources at a 2E cut-off grade of 0.11opt at Stillwater Mine is justified. While a higher 2E cut-off grade has been used for reporting the Mineral Resources at Stillwater Mine than for East Boulder Mine, the Qualified Persons consider it more appropriate and therefore recommend the reporting of Mineral Resources at the 2E cut-off grade of 0.05opt at both mines. Aligning the cut-off grade will more fully reflect the Mineral Resource potential of the J-M Reef than the 0.11opt used at Stillwater Mine which is driven by high operating costs during the production ramp up phase. Mineral Resource Estimates 31 December 2023 Mineral Resource Statements The Mineral Resource estimates for Stillwater and East Boulder Mines as at the end of the fiscal year ended 31 December 2023 are summarised in Table 21 and Table 22. The Mineral Resource estimates in Table 21 are reported inclusive of Mineral Reserves while the estimates in Table 22 are reported exclusive of Mineral Reserves. These estimates are in situ estimates of tonnage and grades (point of reference) 108 reported at a minimum mining width of 7.5ft, which is applicable for the dominant ramp and fill underground mining method at Stillwater and East Boulder Mines. Furthermore, the Mineral Resources are reported at 2E cut-off off grades of 0.11opt (3.44g/t) and 0.05opt (1.71g/t) at Stillwater and East Boulder Mines, respectively. Individual metal grades are based on prill splits (metal ratio) data routinely collected at the concentrators, which are summarised in Table 47. No metal equivalents are reported as these are irrelevant to Stillwater and East Boulder Mines. The Qualified Persons with responsibility for reporting and sign-off of the Mineral Resources for Stillwater and East Boulder Mines are Jeff Hughs and Jennifer Evans, respectively. Jennifer and Jeff are Professional Geologists with more than five years of experience relevant to the estimation and reporting of Mineral Resources and mining of the J-M Reef at Stillwater and East Boulder Mines. Table 21: Mineral Resource Estimates Inclusive of Mineral Reserves at the End of the Fiscal Year Ended 31 December 2023 Based on Pd and Pt Price of $1 500/oz Description Mineral Resources Inclusive of Mineral Reserves Imperial Category Mine Tons (Million) Pd (opt) Pt (opt) 2E (opt) 2E Content (Moz) Measured Stillwater 30.7 0.38 0.11 0.49 15.1 East Boulder 18.3 0.28 0.08 0.36 6.6 Subtotal/Average 49.0 0.35 0.10 0.44 21.7 Indicated Stillwater 25.7 0.38 0.11 0.49 12.5 East Boulder 28.4 0.27 0.08 0.35 10.0 Subtotal/Average 54.1 0.32 0.09 0.41 22.4 Measured + Indicated Stillwater 56.4 0.38 0.11 0.49 27.6 East Boulder 46.8 0.28 0.08 0.35 16.6 Subtotal/Average 103.1 0.33 0.09 0.43 44.1 Inferred Stillwater 64.0 0.27 0.08 0.35 22.4 East Boulder 61.5 0.27 0.08 0.35 21.3 Subtotal/Average 125.5 0.27 0.08 0.35 43.7 Metric Category Mine Tonnes (Million) Pd (g/t) Pt (g/t) 2E (g/t) 2E Content (Moz) Measured Stillwater 27.8 13.15 3.75 16.90 15.1 East Boulder 16.6 9.65 2.68 12.33 6.6 Subtotal/Average 44.5 11.84 3.35 15.19 21.7 Indicated Stillwater 23.3 12.96 3.69 16.65 12.5 East Boulder 25.8 9.40 2.61 12.01 10.0 Subtotal/Average 49.1 11.09 3.12 14.21 22.4 Measured + Indicated Stillwater 51.1 13.06 3.72 16.79 27.6 East Boulder 42.4 9.50 2.64 12.13 16.6 Subtotal/Average 93.6 11.45 3.23 14.68 44.1 Inferred Stillwater 58.0 9.35 2.66 12.01 22.4 East Boulder 55.8 9.29 2.58 11.87 21.3 Subtotal/Average 113.8 9.32 2.62 11.94 43.7 2E Cut-off Grade Stillwater Mine – 0.11opt (3.77g/t) 2E Cut-off Grade East Boulder Mine – 0.05opt (1.71g/t) Pd Price – $1 500/oz Pt Price – $1 500/oz 2E Recovery Stillwater Mine – 91.48% 2E Recovery East Boulder Mine – 90.33% Pd:Pt Ratio Stillwater Mine – 3.51:1 Pd:Pt Ratio East Boulder Mine – 3.60:1 109 Table 22: Mineral Resource Estimates Exclusive of Mineral Reserves at the End of the Fiscal Year Ended 31 December 2023 Based on Pd and Pt Price of $1 500/oz Description Mineral Resources Exclusive of Mineral Reserves Imperial Category Mine Tons (Million) Pd (opt) Pt (opt) 2E (opt) 2E Content (Moz) Measured Stillwater 16.1 0.27 0.08 0.34 5.5 East Boulder 7.2 0.25 0.07 0.32 2.3 Subtotal/Average 23.2 0.26 0.07 0.34 7.8 Indicated Stillwater 11.4 0.20 0.06 0.26 3.0 East Boulder 9.8 0.22 0.06 0.28 2.7 Subtotal/Average 21.3 0.21 0.06 0.27 5.7 Measured + Indicated Stillwater 27.5 0.24 0.07 0.31 8.5 East Boulder 17.0 0.23 0.06 0.30 5.0 Subtotal/Average 44.5 0.24 0.07 0.30 13.5 Inferred Stillwater 64.0 0.27 0.08 0.35 22.4 East Boulder 61.5 0.27 0.08 0.35 21.3 Subtotal/Average 125.5 0.27 0.08 0.35 43.7 Metric Category Mine Tonnes (Million) Pd (g/t) Pt (g/t) 2E (g/t) 2E Content (Moz) Measured Stillwater 14.6 9.15 2.61 11.76 5.5 East Boulder 6.5 8.61 2.39 11.00 2.3 Subtotal/Average 21.1 8.99 2.54 11.53 7.8 Indicated Stillwater 10.4 6.98 1.99 8.96 3.0 East Boulder 8.9 7.47 2.07 9.54 2.7 Subtotal/Average 19.3 7.20 2.03 9.23 5.7 Measured + Indicated Stillwater 24.9 8.25 2.35 10.60 8.5 East Boulder 15.4 7.95 2.21 10.16 5.0 Subtotal/Average 40.4 8.13 2.30 10.43 13.5 Inferred Stillwater 58.0 9.35 2.66 12.01 22.4 East Boulder 55.8 9.29 2.58 11.87 21.3 Subtotal/Average 113.8 9.32 2.62 11.94 43.7 2E Cut-off Grade Stillwater Mine – 0.11opt (3.77g/t) 2E Cut-off Grade East Boulder Mine – 0.05opt (1.71g/t) Pd Price – $1 500/oz Pt Price – $1 500/oz 2E Recovery Stillwater Mine – 91.48% 2E Recovery East Boulder Mine – 90.33% Pd:Pt Ratio Stillwater Mine – 3.51:1 Pd:Pt Ratio East Boulder Mine – 3.60:1 Mineral Resource Reconciliation Table 23 and Table 24 show a reconciliation between the 31 December 2023 and the 31 December 2022 Mineral Resource estimates for Stillwater and East Boulder Mines. Both estimates were reported at the same cut-off grades and minimum mining width and disclosed by the Registrant. The reconciliation shows year-on-year changes where positive and negative values respectively indicate increases and decreases from the 31 December 2022 figures disclosed by the Registrant. The reconciliation indicates modest year-on-year change in tonnage, grade and 2E metal content resulting from the combination of mining depletion between the two reporting periods (0.7 million tons at Stillwater Mine and 0.6 million tons at East Boulder Mine), grade block model updates and changes in Mineral Resource classification boundaries as a result of additional definition drilling. 110 Table 23: 31 December 2022 to 31 December 2023 Mineral Resource Reconciliation (Mineral Resources Inclusive of Mineral Reserves) Description Year-on-Year Change in Mineral Resources Inclusive of Mineral Reserves Imperial Category Mine Tons (Million) Pd (opt) Pt (opt) 2E (opt) 2E Content (Moz) Measured Stillwater 2.2 0.04 0.01 0.06 2.7 East Boulder (0.1) 0.02 0.00 0.02 0.4 Subtotal/Average 2.1 0.03 0.01 0.04 3.0 Indicated Stillwater (0.8) 0.05 0.01 0.06 1.2 East Boulder (0.7) 0.02 0.01 0.03 0.5 Subtotal/Average (1.5) 0.03 0.01 0.04 1.7 Measured + Indicated Stillwater 1.4 0.05 0.01 0.06 3.9 East Boulder (0.8) 0.02 0.01 0.02 0.8 Subtotal/Average 0.6 0.03 0.01 0.04 4.8 Inferred Stillwater 0.1 (0.01) (0.00) (0.01) (0.5) East Boulder (0.3) (0.01) (0.00) (0.01) (0.6) Subtotal/Average (0.2) (0.01) (0.00) (0.01) (1.1) Metric Category Mine Tonnes (Million) Pd (g/t) Pt (g/t) 2E (g/t) 2E Content (Moz) Measured Stillwater 2.0 1.50 0.43 1.92 2.7 East Boulder (0.1) 0.57 0.16 0.72 0.4 Subtotal/Average 1.9 1.20 0.34 1.54 3.0 Indicated Stillwater (0.7) 1.63 0.47 2.10 1.2 East Boulder (0.6) 0.67 0.19 0.86 0.5 Subtotal/Average (1.3) 1.12 0.32 1.44 1.7 Measured + Indicated Stillwater 1.3 1.57 0.45 2.01 3.9 East Boulder (0.7) 0.63 0.18 0.81 0.8 Subtotal/Average 0.6 1.17 0.33 1.50 4.8 Inferred Stillwater 0.1 (0.22) (0.06) (0.28) (0.5) East Boulder (0.3) (0.22) (0.06) (0.28) (0.6) Subtotal/Average (0.2) (0.22) (0.06) (0.28) (1.1) 2E Cut-off Grade Stillwater Mine – 0.11opt (3.77g/t) 2E Cut-off Grade East Boulder Mine – 0.05opt (1.71g/t) Pd Price – $1 500/oz Pt Price – $1 500/oz 2E Recovery Stillwater Mine – 91.48% 2E Recovery East Boulder Mine – 90.33% Pd:Pt Ratio Stillwater Mine – 3.51:1 Pd:Pt Ratio East Boulder Mine – 3.60:1 Table 24: 31 December 2022 to 31 December 2023 Mineral Resource Reconciliation (Mineral Resources Exclusive of Mineral Reserves) Description Year-on-Year Change in Mineral Resources Exclusive of Mineral Reserves Imperial Category Mine Tons (Million) Pd (opt) Pt (opt) 2E (opt) 2E Content (Moz) Measured Stillwater 1.5 0.03 0.01 0.03 1.0 East Boulder 0.5 0.02 0.01 0.03 0.4 Subtotal/Average 2.0 0.03 0.01 0.03 1.4 Indicated Stillwater (0.5) 0.03 0.01 0.04 0.3 East Boulder 0.7 0.03 0.01 0.04 0.6 Subtotal/Average 0.2 0.03 0.01 0.04 0.9 Measured + Indicated Stillwater 1.0 0.03 0.01 0.04 1.3 East Boulder 1.2 0.03 0.01 0.04 0.9 Subtotal/Average 2.2 0.03 0.01 0.04 2.3 Inferred Stillwater 0.1 (0.01) (0.00) (0.01) (0.5) East Boulder (0.3) (0.01) (0.00) (0.01) (0.6) Subtotal/Average (0.2) (0.01) (0.00) (0.01) (1.1)


111 Description Year-on-Year Change in Mineral Resources Exclusive of Mineral Reserves Imperial Category Mine Tons (Million) Pd (opt) Pt (opt) 2E (opt) 2E Content (Moz) Metric Category Mine Tonnes (Million) Pd (g/t) Pt (g/t) 2E (g/t) 2E Content (Moz) Measured Stillwater 1.4 0.91 0.26 1.17 1.0 East Boulder 0.4 0.82 0.23 1.05 0.4 Subtotal/Average 1.8 0.88 0.25 1.13 1.4 Indicated Stillwater (0.5) 1.00 0.28 1.28 0.3 East Boulder 0.7 1.12 0.31 1.43 0.6 Subtotal/Average 0.2 1.07 0.30 1.36 0.9 Measured + Indicated Stillwater 0.9 1.02 0.29 1.32 1.3 East Boulder 1.1 0.99 0.28 1.27 0.9 Subtotal/Average 2.0 1.01 0.28 1.29 2.3 Inferred Stillwater 0.1 (0.22) (0.06) (0.28) (0.5) East Boulder (0.3) (0.22) (0.06) (0.28) (0.6) Subtotal/Average (0.2) (0.22) (0.06) (0.28) (1.1) 2E Cut-off Grade Stillwater Mine – 0.11opt (3.77g/t) 2E Cut-off Grade East Boulder Mine – 0.05opt (1.71g/t) Pd Price – $1 500/oz Pt Price – $1 500/oz 2E Recovery Stillwater Mine – 91.48% 2E Recovery East Boulder Mine – 90.33% Pd:Pt Ratio Stillwater Mine – 3.51:1 Pd:Pt Ratio East Boulder Mine – 3.60:1 112 MINERAL RESERVE ESTIMATES Mineral Resource to Mine Reserve Conversion Methodology Mineral Resources Available for Conversion Prior to commencing the planning process at Stillwater and East Boulder Mines, the first stage was to define the Mineral Resources available for conversion to Mineral Reserves – these being Indicated and Measured Mineral Resources. The Mineral Resource model identified the tonnages, grades and 2E content available for conversion. Mineral Reserve Estimation Methodology Mineral Reserves for Stillwater and East Boulder Mines were prepared from a business and LoM planning process which converted Indicated and Measured Mineral Resources to Mineral Reserves. The Mineral Reserves were classified using criteria set out in Section 12.2. The conversion took into consideration all the modifying factors for the various disciplines relevant to Mineral Reserves, namely mining methods, mining and surveying factors, ore processing and metallurgical recoveries, infrastructure engineering and equipment, market conditions, environmental and social matters, and capital and operating costs (Section 12 to 18). The LoM plan production schedules generated were tested for economic viability using a set of reasonable economic parameters prior to the declaration of Mineral Reserves (Section 19). Despite the common estimation methodology employed for Indicated and Measured Mineral Resources, different approaches were followed for the scheduling of Indicated and Measured Mineral Resources to derive the LoM production schedules underpinning the Mineral Reserves for Stillwater and East Boulder Mines (Section 13.7). This is due to different levels of confidence between the Mineral Resource classes resulting from different drillhole data point spacing given the high microvariability of the J-M Reef. Scheduling of the Measured Mineral Resources and conversion to Proved Mineral Reserves benefitted from the high abundance of geological information available to accurately constrain thickness, tonnage and grades. However, the scheduling of the Indicated Mineral Resources and conversion to Probable Mineral Reserves relied on statistics and key metrics extrapolated from the Proved Mineral Reserve areas per domain and mining block. The Mineral Reserves were estimated for each of the sub-areas at both Stillwater Mine and East Boulder Mines. The conversion of Mineral Resources to Mineral Reserves at the mines follows a methodology that was developed in 1990 and adjusted as required over the years as more geological and mining information became available. The methodology accounts for the different reef facies and the sub- areas that exist at the mines and the fact that a single set of parameters within a sub-area can be used to confidently project surface and underground drilling for Mineral Resource estimates. Mining experience and reconciliation between Mineral Reserve estimates and actual production figures have demonstrated the robustness of the methodology in making estimates of tonnages and ounces that have historically been reported as Mineral Reserves. 113 The following key technical parameters, assumptions and mining modifying factors were utilised to develop the mine designs and LoM production schedules as discussed in Sections 12 and 13:  Cut-off grade;  Percentage ore recovered;  Geotechnical and geohydrological considerations;  Mining method and applicable minimum mining widths;  Dilution (planned and unplanned overbreak);  Deletion;  Extraction rate;  Extraction sequence;  Planned productivity;  Equipment and personnel equipment requirements; and  Fill requirements (type and quantity). The LoM planning and subsequent production scheduling was developed utilising historical productivity parameters inclusive of the following:  Stoping tons per miner per month per mining method;  Ore tons generated per foot of footwall development;  Primary development productivities, feet advance per month; and  Secondary development productivities, feet advance per month; Historical analysis of mine planning and production data revealed that a recovery factor of 75% was required to reconcile blasted and removed tons in the sub-level extraction stopes. Therefore, a 75% recovery factor was applied to all sub-level extraction tons and ounces to Mineral Reserves. Furthermore, mineability block factors (MBFs) indicated in Table 36 were applied to tonnage estimates when converting Indicated Mineral Resources to Probable Mineral Reserves. A MBF is calculated as the percentage of the fully diluted ore grade tonnage within a mineable area compared with the total fully diluted ore grade tonnage within the boundary area of a block or percent of material historically extracted from the block. Initially, scheduling included all primary development (footwall lateral drifts) to access the stope blocks in the Measured Mineral Resource areas. Thereafter, the development design and scheduling were extended into the Indicated Mineral Resource areas where primary annual development rates were derived through the utilisation of historical ratios. The scheduling of the stoping was dependent on the completion of the footwall access and the necessary diamond drilling to form an outline of the stopable areas in terms of grade and tonnage. In addition, the scheduling was also dependent on the mill feed requirements. On the completion of the lateral development schedule, the starting dates for the development of the stoping blocks were defined based on when access will be attained and the mines’ requirements in terms of RoM ore production. It is also during this process that the true width was corrected for dip and a minimum mining width was applied dependant on mining method and type of equipment to be employed. 114 For each stope block, a proposal (business plan) was drawn up which included, amongst other information, primary and secondary development requirements, reef widths, tonnage and forecasted grade, expected percentage ore recovery, applied cut-off grades, overall stope design, mining method to be employed, ventilation requirements, backfill requirements extraction sequence, and manpower and mining equipment requirements. Once the technical inputs were defined, each stope block was subjected to an economic test. This economic test used technical and financial parameters to determine the economic viability of the planned stoping operations. It accounted for all costs associated with the ore extraction and balanced the total costs against the revenue generated by the block. From the process, a Net Present Value (NPV) of the planned stope was determined. Where required (e.g., if a stope does not meet the required financial returns), the stope was optimised to return the best value. The tonnage and grades in the LoM production schedules were aggregated to derive Mineral Reserve tons and grades, with the tonnage and grades scheduled in the Measured Mineral Resources supported by definition drillhole data classified as Proved and those in the Indicated and Measured Mineral Resources supported by surface drillhole data but no definition drillhole data classified as Probable. The Qualified Person can confirm that the process followed to convert the Measured Mineral Resources into Proved Mineral Reserves was based on historical performance and reconciliations, with input and outputs reported within the accuracy level of ±15%. The process followed to convert the Indicated and Measured Mineral Resources to Probable Mineral Reserves utilised statistics from the Proved Mineral Reserves and a geological block model at a lower level of confidence resulting in the outputs reported within ±25% accuracy. Point of Reference The aggregated scheduled tonnages and grades reflected in the LoM production schedules and delivered to the concentrators for processing at Stillwater and East Boulder Mines are the tonnage and grade estimates reported as the Mineral Reserve estimates. Therefore, the mill head is the point of reference for Mineral Reserve reporting. Cut-off Grades The 2E cut-off grades for Mineral Reserve reporting are 0.20opt (6.86g/t) for Stillwater Mine and 0.05opt (1.71g/t) for the East Boulder Mine. All diluted blocks within the individual stope outlines that are above the cut-off grade were included in the Mineral Reserves. The 2E cut-off grades were selected as the optimal cut-off grades that ensure continuity of the mineable portions of the reef and enable achievement of targeted production efficiencies while optimising NPV. Using the parameters in Table 20, the Qualified Person determined the minimum 2E grades required to pay for the extraction and processing of a ton of high-grade ore at Stillwater and East Boulder Mines of 0.51opt and 0.34opt, respectively. This approach leaves the mined low-grade material underground, which would be inappropriate if there is unused hoisting and ore processing plant capacities. As a result, the Qualified Person also determined the 2E cut-off grades based on the incremental cost of hoisting


115 and processing the low-grade material inevitably mined to access the high-grade ore. The resulting minimum 2E grades determined are 0.08opt and 0.05opt for Stillwater and East Boulder Mines, respectively. The metal prices used are long-term forecast prices for platinum and palladium. Section 16.4 the rationale for the price forecast. Costs employed for cut-off grade calculation are current actual operating costs. As the low-grade (0.05opt to 0.34opt 2E) material being economically mined and milled together with the high-grade material (greater than 0.34opt 2E) at East Boulder Mine, the Qualified Person elected to use 0.05opt as the 2E cut-off grade for Mineral Reserve reporting in the mechanised ramp and fill mining areas. This is aligned to the minimum 2E grade derived through consideration of the incremental cost of hoisting and processing and the current practice of milling RoM ore comprising high-grade and low- grade material. The planned commissioning of additional concentrator capacity at Stillwater Mine places Stillwater Mine in a similar place as East Boulder Mine. However, higher operating costs at Stillwater necessitated the use of higher 2E cut-off grades than for East Boulder Mine. Applying the same logic for cut-off grade determination as at East Boulder, the Qualified Person elected to use 0.2opt as the 2E cut-off grade for Mineral Reserve reporting in the mechanised ramp and fill mining areas. The Qualified Person also noted that the Stillwater Mine is still ramping up production and its current operating costs exceed steady state operating costs. As such, the 2E cut-off grades should be reviewed in future taking in account operating costs as production output increases as well as the available hoisting and ore processing capacity to process both the high-grade and low-grade material at steady state. Mineral Reserve Classification Criteria The tonnage and grades in the LoM production schedules were aggregated to derive Mineral Reserve tons and grades. The tonnage and grades scheduled in the Measured Mineral Resource areas where there is definition drillhole data were classified as Proved Mineral Reserves. The tonnage and grades scheduled in the Measured and Indicated Mineral Resources where there is no definition drillhole data were classified as Probable Mineral Reserves. The Qualified Person can confirm that the process followed to convert the Measured Mineral Resources into Proved Mineral Reserves is based on historical performance and reconciliations, with input and outputs reported within the accuracy level of ±15%. The process followed to convert the Indicated Mineral Resources to Probable Mineral Reserves utilised statistics from the Proved Mineral Reserves and a geological block model at a lower level of confidence and, as a result, the outputs are reported within ±25% accuracy. Mineral Reserve classification maps for Stillwater and East Boulder Mines are shown in Figure 50 and Figure 51 respectively. 116 Figure 50: Mineral Reserve classification for Stillwater Mine 117 Figure 51: Mineral Reserve classification for East Boulder Mine 118 Mineral Reserve Estimates 31 December 2023 Mineral Reserve Statement The Mineral Reserve estimates for Stillwater and East Boulder Mines as at 31 December 2023 are reported in Table 25. Only the Measured and Indicated portions of the Mineral Resources within the LoM plans have been included in the Mineral Reserve. No Inferred Mineral Resources have been included in Mineral Reserve estimates. The reference point for tonnage and grade estimates for the Mineral Reserve estimates is the mill head and the Mineral Reserve estimates are reported at the 2E cut-off grade of 0.20opt (6.86g/t) and 0.05opt (1.71g/t) at Stillwater and East Boulder Mines, respectively. The tonnages and 2E grades indicate the expected RoM ore tonnages and grades derived through LoM production scheduling. Individual metal grades are based on the application of prill splits (metal ratios) which are summarised in Table 47 and were determined from actual data routinely collected at the Stillwater and East Boulder Concentrators. The Qualified Persons with responsibility for reporting and sign-off of the Mineral Reserves for Stillwater and East Boulder Mines are Annette McFarland and Pat Hansen, respectively. The Qualified Persons are Registered Professional Engineers with more than five years of experience relevant to the estimation and reporting of Mineral Reserves and mining of the J-M Reef at Stillwater and East Boulder Mines. Table 25: Mineral Reserve Estimates at the End of the Fiscal Year Ended 31 December 2023 Based on Pd and Pt Price of $1 250/oz Description Mineral Reserves Imperial Category Mine Tons (Million) Pd (g/t) Pt (g/t) 2E (opt) 2E Content (Moz) Proved Stillwater 7.5 0.34 0.10 0.44 3.3 East Boulder 4.6 0.25 0.07 0.32 1.5 Subtotal/Average 12.1 0.31 0.09 0.39 4.8 Probable Stillwater 27.5 0.35 0.10 0.45 12.4 East Boulder 27.0 0.26 0.07 0.34 9.1 Subtotal/Average 54.5 0.31 0.09 0.40 21.5 Proved + Probable Stillwater 35.0 0.35 0.10 0.45 15.7 East Boulder 31.6 0.26 0.07 0.33 10.6 Total/Average 66.6 0.31 0.09 0.40 26.3 Metric Category Mine Tonnes (Million) Pd (g/t) Pt (g/t) 2E (g/t) 2E Content (Moz) Proved Stillwater 6.8 11.73 3.34 15.07 3.3 East Boulder 4.2 8.62 2.39 11.01 1.5 Subtotal/Average 10.9 10.55 2.98 13.53 4.8 Probable Stillwater 25.0 12.07 3.44 15.51 12.4 East Boulder 24.5 9.05 2.51 11.56 9.1 Subtotal/Average 49.5 10.57 2.98 13.55 21.5 Proved + Probable Stillwater 31.7 12.00 3.42 15.41 15.7 East Boulder 28.7 8.98 2.49 11.48 10.6 Total/Average 60.4 10.57 2.98 13.55 26.3 2E Cut-off Grade Stillwater Mine – 0.20opt (6.86g/t) 2E Cut-off Grade East Boulder Mine – 0.05opt (1.71g/t) Mineral Reserve Declaration Pd and Pt Price – $1 250/oz Cut-off Determination Pd Price – $1 250/oz Cut-off Determination Pt Price – $1 250/oz 2E Recovery Stillwater Mine – 91.48% 2E Recovery East Boulder Mine – 90.33% Pd:Pt Ratio Stillwater Mine – 3.51:1


119 Description Mineral Reserves Pd:Pt Ratio East Boulder Mine – 3.60:1 Mineral Reserve Reconciliation Table 26 shows a reconciliation between the 31 December 2023 and the 31 December 2022 Mineral Reserve estimates for Stillwater and East Boulder Mines which were reported at the same cut-off grades and minimum mining width and disclosed by the Registrant. These also show year-on-year changes where positive and negative values respectively indicate increases and decreases from the 31 December 2022 figures. The reconciliation shows modest year-on-year change in the tonnage and grades resulting from mining depletion between the two reporting periods (0.7 million tons at Stillwater Mine and 0.6 million tons at East Boulder Mine), block model update, Mineral Reserve classification boundaries and refinements to the modifying factors used for the conversion of Mineral Resources to Mineral Reserves during mine planning. Table 26: 31 December 2022 to 31 December 2023 Mineral Resource Reconciliation Description Year-on-Year Change in Mineral Reserves Imperial Category Mine Tons (Million) Pd (g/t) Pt (g/t) 2E (opt) 2E Content (Moz) Proved Stillwater 0.8 0.01 0.00 0.01 0.5 East Boulder 0.2 (0.02) (0.01) (0.02) (0.0) Subtotal/Average 1.1 0.00 0.00 0.00 0.4 Probable Stillwater (1.2) 0.01 0.00 0.02 0.0 East Boulder 0.3 (0.02) (0.00) (0.02) (0.4) Subtotal/Average (0.9) (0.00) (0.00) (0.00) (0.4) Proved + Probable Stillwater (0.4) 0.01 0.00 0.02 0.5 East Boulder 0.5 (0.02) (0.00) (0.02) (0.5) Total/Average 0.2 (0.00) (0.00) (0.00) 0.0 Metric Category Mine Tonnes (Million) Pd (g/t) Pt (g/t) 2E (g/t) 2E Content (Moz) Proved Stillwater 0.7 0.37 0.11 0.48 0.5 East Boulder 0.2 (0.67) (0.19) (0.85) (0.0) Subtotal/Average 1.0 0.01 0.01 0.01 0.4 Probable Stillwater (1.1) 0.51 0.15 0.66 0.0 East Boulder 0.3 (0.53) (0.15) (0.68) (0.4) Subtotal/Average (0.8) (0.03) (0.01) (0.04) (0.4) Proved + Probable Stillwater (0.3) 0.48 0.14 0.61 0.5 East Boulder 0.5 (0.55) (0.15) (0.71) (0.5) Total/Average 0.1 (0.03) (0.01) (0.03) 0.0 2E Cut-off Grade Stillwater Mine – 0.20opt (6.86g/t) 2E Cut-off Grade East Boulder Mine – 0.05opt (1.71g/t) Mineral Reserve Declaration Pd and Pt Price – $1 250/oz Cut-off Determination Pd Price – $1 250/oz Cut-off Determination Pt Price – $1 250/oz 2E Recovery Stillwater Mine – 91.48% 2E Recovery East Boulder Mine – 90.33% Pd:Pt Ratio Stillwater Mine – 3.51:1 Pd:Pt Ratio East Boulder Mine – 3.60:1 120 Risk Assessments The Qualified Persons have completed a high-level semi-quantitative risk analysis of the Sibanye- Stillwater US PGM Operations discussed in this TRS. The risk analysis sought to establish how the Mineral Reserve estimates for Stillwater and East Boulder Mines could be materially affected by risk factors associated with or changes to any aspect of the modifying factors. For the high-level risk analysis, the Qualified Persons have assessed a material risk identified as an issue for which there is a substantial likelihood that a reasonable investor would attach importance in determining whether to buy or sell the securities registered for Sibanye-Stillwater. A material risk should also have a high chance (likelihood) of occurrence. If an issue does not satisfy both criteria, it has been identified as a low to medium risk depending on its impact if it occurs and the likelihood of occurrence. Sibanye-Stillwater has a risk management process in place at the Sibanye-Stillwater US PGM Operations that identifies risks, assesses the materiality of the risks, and provides risk mitigation measures where possible. The Qualified Persons participate in the risk assessment for the LoM plans and Mineral Reserves. Sibanye-Stillwater’s risk management process identified various material risks to LoM plans and Mineral Reserves relating to geotechnical and geohydrological uncertainties, inability to execute LoM plans, metal price downturns, inadequate tailings storage capacity, unplanned production cost escalation, unplanned power outages and restricted access to the operations caused by extreme weather events. Sibanye-Stillwater has mitigated (and not eliminated) these risks as per its risk management protocols to reduce the likelihood of occurrence and/or impact (severity) when the risk occurs which resulted in a reclassification of the residual risks as low to medium risks. The Qualified Persons consider the risk management process robust and sufficient to identify material risks that should be mitigated to enhance the achievability of the LoM plans. From their appraisal of the residual risks after mitigation, the Qualified Persons could not identify any unmitigated material risks to the LoM plans and Mineral Reserves associated with the modifying factors or resulting from changes to any aspect of the modifying factors. The Qualified Persons provide the following opinions relating to the low to medium risks identified in the modifying factors and the mitigation measures in place to minimise the impact of the risks:  Geotechnical: Stillwater and East Boulder Mines have accumulated an extensive geotechnical database and developed ground classification (ground control districts) and support measures that are suited to the rockmass conditions for each of the ground control districts. These measures have significantly reduced major falls of ground at Stillwater and East Boulder Mines. However, there is always a degree of residual low risk relating to excavation failures. The extensive support systems and standards in place at both mines are sufficient to minimise the potential impact of any geotechnical associated risk.  Geohydrological: Mining operations at Stillwater and East Boulder Mines have not experienced material interruptions due to groundwater problems, with both mines being relatively dry in the upper sections. However, a significant amount of groundwater was encountered at the Stillwater East Section during the development of the main access adits and the decline, but conditions have improved significantly with further development. Despite the declining groundwater inflow, the groundwater poses a low risk in terms of excavation stability and the management and disposal of the water generated. Stillwater Mine has already initiated a multi-pronged approach to mitigating this risk which involve the following: o The drilling of probe holes well in advance of any advancing development end; 121 o Carrying out hydraulic tests of probe holes drilled prior to drift advancement whenever practically possible; o Cementation (grouting) ahead of those advancing development ends where the potential for significant water intersections have been identified; o Probe and definition drilling before developing new production areas to evaluate water inflows, with some of these drillholes converted into drain holes for dewatering purposes; and o Evaluating, engineering, and permitting expanded water handling and disposal facilities on surface to manage excess mine water.  Inability to execute LoM plans: Although mining experience at the Stillwater and East Boulder Mines has provided improved understanding of the mineralisation, modelling ability and understanding of the modifying factors, estimation errors cannot be eliminated. The major expected sources of error in the Mineral Reserve estimates include understating production costs, slower than planned production build-ups, understating manpower requirements, regulatory changes, grade and tonnage underestimation and unknown geological conditions. These factors are partially mitigated by using a significant amount of historical data in the LoM forecasting of key elements of the operations, namely RoM ore production levels, RoM ore grades and operating costs. Furthermore, the mines have systems and personnel in place that monitor the mining operations daily (short interval control) to enable the implementation of timeous interventions and, therefore, correction of deviations to the plans.  Unplanned production cost escalation: In recent years since 2019 until 2023, there has not been significant escalation of the production costs. The production costs were mainly affected by the quantities of ore and waste produced each year from each mine and the mining methods employed, with the cost-effective mechanised ramp and fill methods utilised for most stopes at both mines. Continuous improvement initiatives adopted to contain cost escalation included the increasing use of mechanised mining methods thereby improving productivities and reducing operating costs, the optimisation of the mining fleets (reducing active units) to reduce maintenance costs and increase mining volumes through mining footprint expansion at Stillwater Mine (Stillwater East Section) and optimal utilisation of available hoisting and milling capacities at East Boulder (Fill The Mill Project). Since 2020 and coinciding with the COVID-19 pandemic, the operations have experienced significant cost pressures due to external and internal factors which were compounded by production disruptions caused by the COVID-19 pandemic. The operations have embarked on recovery efforts and production ramp up to reverse the adverse impacts on production due to the COVID-19 pandemic.  Power losses: The loss of power at the mining operations during the winter months (due to excessive snow and high winds) is the single low to medium risk identified relating to mining infrastructure. The power losses are infrequent and are mitigated by using backup generators. The generators have sufficient capacity to power communication systems and shaft conveyances to ensure that personnel can be safely withdrawn.  Inadequate tailings storage capacity: Tailings storage facilities at Stillwater and East Boulder Mines have adequate storage capacity for the medium term (seven to ten-year range). Production increases at both mines have shortened the lives of the tailings storage capacities. Tailings storage capacity upgrade through elevation lift is a mitigation measure that has been adopted while permitting for the construction of new tailings facilities is being pursued. Permitting for the construction of a new tailings storage facility may require periods of three to five years. Sibanye- Stillwater is aware of the long approval timeframes and has already completed the necessary technical studies and submitted the required permit applications to initiate the permitting processes. It is unlikely that the operations will run out of tailings storage facility capacity before Sibanye-Stillwater receives approvals for the construction of new tailings storage facilities or the upgrading of the existing tailings storage facilities. 122  Metal price downturns: The prices for palladium and platinum fluctuate depending on global supply and demand. Demand for palladium and platinum primarily depend on their use in auto- catalytic converters for both gasoline and diesel engines. The use of platinum and palladium in the hydrogen economy is anticipated to become an additional key demand driver for these metals. Sensitivity analysis of the NPV for the Sibanye-Stillwater US PGM Operations for variation in metal prices indicates robust economics due to the high-grade nature of the J-M Reef and that significant revisions of the Mineral Reserves for Stillwater and East Boulder Mines would only result from a significant metal price decrease. The estimated revenue per combined ounce of palladium and platinum over the LoM plans varies depending on which parts of each of the mines are being exploited. This offers the mines the flexibility to delay the mining of sub-economic areas during times of price downturns.  Restricted access to the operations caused by extreme weather events: Freezing temperatures in winter and snow can pose adverse operating conditions, although avalanches from the steep mountain slopes have never directly affected operations at the mines. Snow removal and road maintenance by Sibanye-Stillwater has effectively been used to maintain mine access even in winter storms. On 13 June 2022, a 500-year flood resulting from the combination of warm weather triggering an unusual ice melt and incessant rains in Montana destroyed parts of State Highway 419 used to access Stillwater Mine. The damage caused restricted access to the mine, temporary suspension of the mining operations for seven weeks. A temporary road was built to reestablish access to and from the mine to support full operations at the mine while repairs were being carried out on the damaged parts of the highway resulting in access restoration through the highway in July 2023. The Qualified Persons consider the likelihood of a recurrence of another 500-year flood low which makes flooding due to incessant rains and destruction of access roads a low to medium risk.


123 MINING METHODS Introduction Stillwater and East Boulder Mines are mature operations extracting the J-M Reef using well-established mining methods. Most of the permanent infrastructure required to access the underground operations is already established and being upgraded where necessary to accommodate production increases anticipated in the LoM plans for the operations. The LoM plans for Stillwater and East Boulder Mines, which underlie the Mineral Reserves, were constructed internally by Sibanye-Stillwater’s Qualified Persons supported by Technical Experts and utilising modifying factors and capital and operating costs which are informed by historical experience at the mines. Accordingly, the technical inputs, modifying factors, staffing levels, capital and operating costs utilised for LoM production planning and conversion of Measured Mineral Resources to Proved Mineral Reserves are within ±15% accuracy and the costs allow for up to 10% contingency. However, for the LoM production planning and conversion of Indicated Mineral Resources to Probable Mineral Reserves, the inputs and costs are within ±15% accuracy and the costs allow for up to 10-15% contingency. The economic viability of the LoM plans was assessed through detailed cash flow analysis. Mining recovery (stope extraction) factors are discussed in Section 13.2.4 of this TRS. Mine Design Mining Method Rationale The J-M Reef outcrops over a 28-mile strike length on the Sibanye-Stillwater Mining Claims but the topography, altitude and thickness of the reef preclude economic exploitation of the reef through open pit mining methods. Accordingly, waste stripping which would be applicable to an open pit mining is not required. At Stillwater Mine, the dip of the J-M Reef varies from 40° to 90° to the north, with an average of 60°. Reef thickness varies from 3ft to more than 9ft but averages 6ft. The J-M Reef at East Boulder Mine dips 35° to 55° (averaging 50°) to the north. The shallowest dip (35°) is observed in the far west area accessed by the 6500 Level Footwall Lateral. Both Stillwater and East Boulder Mines employ the following underground mining methods, which are suited for the variable steep dips and narrow widths of the J-M Reef:  Mechanised ramp and fill (also referred to as cut and fill) using overhand or underhand approaches; and  Sub-level extraction by longitudinal hole open stoping with subsequent backfill. The captive cut and fill stoping method which was also being used at the mines has been phased out. The mining method mix is adjustable and largely driven by geotechnical considerations as well as mineralisation grade and the requirement to minimise dilution. The percentage distribution (frequency of use) of the two mining methods within each of the mines is shown in Table 27. Mechanised ramp and fill stoping (which includes on-reef sub-level sill development) is the predominant mining method at both mine-sites. The mechanised ramp and fill method allows for maximum selectivity for separating ore and waste. Sub-level extraction long hole stoping is utilised typically in narrow continuous ore zones. Except for open stoping, the mining methods employ high-quality sand or paste as backfill, with limited use of Cemented Rock Fill (CRF) and/or other backfill materials. 124 Table 27: Mining method frequency of use at Stillwater and East Boulder Mines Mining Method Frequency of Use Stillwater Mine East Boulder Mine Mechanised Ramp and Fill 86% 83% Sub-level Extraction Long Hole Open Stoping 14% 17% Mechanised Ramp and Fill Method Mechanised overhand ramp and fill stoping is the predominant mining method at the Stillwater and East Boulder Mines while 11% to 20% of the stopes at the Stillwater Mine are extracted through mechanised underhand ramp and fill stoping. The two ramp and fill applications practiced at the mines are illustrated in Figure 52. The backfill for the mechanised overhand and underhand ramp and fill stoping are predominately sand (classified coarse fraction mill tailings) and paste, respectively; in the past CRF was utilised for limited applications but has been phased out due to logistical constraints. Where ground conditions permit, the overhand method is preferred as it is more cost effective. Where less stable ground conditions dictate, mechanised underhand ramp and fill is applied, with the more expensive paste backfill also used. Up to 12% cement is used in the paste fill, as needed, to provide a stable overhead cemented paste material. Furthermore, development ramp gradients should not exceed 18%. Breast holes are drilled on most of the mechanised ramp and fill stopes areas using single-boom drill jumbos and, after blasting, the broken rock material is loaded by 2.0 cubic-yard LHDs. Figure 52: Mechanised Overhand and Underhand Ramp and Fill Mining Methods Sub-level Extraction and Sub-level Development Where the J-M Reef and hangingwall are competent and the reef has good continuity, sub-level longitudinal open stoping using relatively shorter “long holes” compared to those in other mining districts is applied. This extraction method is illustrated in Figure 53. The sub-levels are driven on the reef plane at 125 20ft to 50ft intervals. Considerable tonnage generated by driving sub-levels in the reef is accounted for as Sub-level Development tonnage; this is accounted for in the “Mechanised Cut and Fill” percentage. Figure 53: Sub-level Extraction (Longitudinal) Long Hole Open Stoping In the sub-level extraction longitudinal stoping method, sub-level sills are driven with narrow single-boom jumbos. The long holes are drilled by long hole pneumatic and electric hydraulic drill rigs. Once the sub- levels are advanced, a drop raise is drilled from the upper sub-level to the lower sub-level and blasted at the end of the stope over the full width of the reef at that point. Blast holes are then drilled downward on a pattern between the sub-levels and blasted towards the open cavity of a slot raise. Support pillars are left in place on approximately 80ft to 100ft intervals on the reef in the stope to minimise hangingwall failure and ore dilution. The broken ore is mucked from the sub-level below using remote-controlled, diesel-powered LHDs and then trammed to the nearest ore pass. In addition to sub-level panel extractions, backstops are extensively utilised. The process is similar to sub-level extraction except that all activities take place on the bottom as there is no access at the top. Stope Extraction Ratios The regional and local extraction ratios computed from actual data for Stillwater and East Boulder Mines are shown in Table 28. The Qualified Person notes that the regional extraction ratios in Table 28 are low as large areas of the reef were previously left unmined due to the use of high cut-off grades when palladium prices were low. Extraction ratios are set to increase as Mineral Reserve 2E cut-off grades have been lowered to 0.20opt and 0.05opt at Stillwater and East Boulder Mines, respectively, in response to increases in the palladium price and increased production output at both mines since 2017. 126 Table 28: Stope Extraction Ratios Scale Mining Method Extraction Ratio (%) Stillwater Mine East Boulder Mine West Section East Section All Sections Local (Stope) Mechanised Ramp and Fill 90 90 95 Long Hole Open Stopes 60 60 60 Regional (Mine) Overall 40 40 50 Hydrogeological Model Stillwater Mine Based on the hydrogeological models for the Stillwater East and West Sections discussed in Section 7.9.1, no known major changes in groundwater conditions are expected in the Stillwater West Section, with this section expected to remain dry on average. For the purposes of mine-water treatment and discharge, the groundwater inflows generated in both sections of the mine are combined. The underground inflows are currently managed using a series of collection sumps, ditches, pipelines and pumping stations that are primarily located in the Off-Shaft West area of the West-Side Mine. Sibanye- Stillwater has considered forecast of groundwater inflows to ensure that the overall water-management system is appropriately designed to handle the anticipated flow rates and is constructed and operational before the mine inflows substantially increase. Furthermore, Sibanye-Stillwater uses these forecasts to ensure operational compliance with permitted water-discharge limits. Stillwater Mine has completed evaluating, engineering and permitting to handle increased flows which may be in the order of 1 600gal per minute maximum and consider the Itasca estimate of 3 790gal per minute in seven years and continuation at rates between this peak and 3 600gal per minute to be overstated. Furthermore, the Itasca estimate is inconsistent with empirical data from the Stillwater East Section indicating inflows of 900gal per minute to 1 500 gal per minute. Stillwater Mine has introduced the following operational interventions to assist with the management of groundwater intersections in underground excavations:  Drilling of probe holes well in advance of any advancing development end;  Carrying out hydraulic tests of probe holes drilled prior to drift advancement whenever practically possible;  Full cover grouting ahead of development that has the potential to intersect significant quantities of groundwater;  Carrying out additional monitoring/testing as warranted if the identified basins exhibit notably different groundwater conditions;  Evaluating groundwater inflows from definition drillholes before developing new production areas and, where appropriate, converting these drillholes into drain holes for depressurisation/dewatering purposes; and  Manifolding drain holes together, wherever possible, to collect the discharge water into a smaller number of flow points that can then be monitored and directed to pumping facilities and setting up all drain holes to record the line pressures and discharges (cumulative volumes rather than instantaneous rates) from separate/individual areas.


127 The Qualified Person is satisfied that most of the potential sources of groundwater have been identified and accounted for in the mine design while appropriate operational interventions have been proposed for the management of groundwater at Stillwater Mine. The designs prescribe direction for development or the placement of crown and rib pillars to protect the underground excavations from uncontrolled water in rushes. The Qualified Person also notes the importance of continuous monitoring using probe drillholes to facilitate early detection of any potential unidentified water sources. East Boulder Mine Mining at East Boulder Mine is planned in areas situated adjacent to active mining fronts that have not experienced any groundwater issues as the host rock has low permeability. Furthermore, these areas are located at a higher elevation than the lowest level of the mine (the 6500 Level) which currently acts as a drawdown point for surrounding groundwater levels. Inflows are likely to be similar or lower than those experienced by historical mining operations, with the average mine-wide water inflow only likely to increase slightly with the increase in development and production activity associated with the higher than historical production in the current LoM plan. One fault system encountered at the 71300 area that bears water and has been slowing development efforts has been accounted for in the mine plan. Significant water will also likely be encountered in other significantly faulted and jointed areas or when encountering alluvial systems associated with surface channels as mining gets within 500ft of surface. The Qualified Person is satisfied that the mine designs for East Boulder Mine prescribe direction for development or the placement of crown and rib pillars to protect the underground excavations from uncontrolled water in rushes. Furthermore, the standard practice at East Boulder Mine of drilling water probe holes prior to any development work to mitigate the risk of encountering water has been adequate in detecting groundwater inflows while diamond drilling on 50ft centres results in a good understanding of water potential before mining activity begins. Geotechnical Model Geotechnical Characterisation The J-M Reef and its immediate hangingwall and footwall consist of varying assemblages of norite, anorthosite, leucotroctolite and peridotite. As the lithological sequence is similar at Stillwater and East Boulder Mines, a universal approach is adopted for support designs at both mines. The rock units contained within the J-M Reef, Footwall and Hangingwall Zones are classified as strong based on UCS ranging from 60Mpa to 85Mpa. Mining and support designs are adjusted accordingly is areas of lower strengths commonly associated with olivine cumulates or when geological structures are identified in the drillcores. The Q-values obtained for Stillwater and East Boulder Mines ranging from 1 to 13 indicate poor to good rock mass conditions, where the overall area split for fair, good and poor conditions is 50%, 25% and 25%, respectively. Support Design The ground support requirements for the primary development are described in the standard operating procedures, which detail the requirements for the three main ground types termed Type 1, 2, and 3. 128 Type 3 ground types has two variants (Type 3 and 3+). Table 29 provides the classification criteria for the ground types while Figure 21 and Figure 22 (Section 7.10.3) show the ground classification maps for Stillwater and East Boulder Mines, respectively. Table 29: Stillwater and East Boulder Mine Ground Types Ground Type Q-Rating RMR Rating Description Minimum Maximum Minimum Maximum Type 3+ 0.1 0.39 23 36 Very poor or poor with water present Type 3 0.4 0.99 36 44 Poor Type 2 1 3.99 44 56 Fair Type 1 4 100 56 85 Good Ground conditions that are assessed by the operations using geotechnical drilling data to be poorer than Type 3 ground will be re-assessed by the Geotechnical Engineer as the many variables causing poor ground mean that it is unlikely that a standard approach can be applied. The Geotechnical Engineer will recommend appropriate support for such areas. Rock mass characteristics determined for the assessment of geotechnical data is used to delineate geotechnical domains of similar characteristics. The ground type domains and applicable ground support requirements are integrated with other design and planning information. Areas which are prone to anomalous rock-related risks are then identified for every planned stope within a “Stope Proposal” document. Ground support employed on the reef is typically pattern-bolting with mesh, which is a combination of friction stabilisers and resin anchor rebar bolts. Due to the requirements to maintain the minimum mining width, it is not possible to drill and install rockbolts in the typical stope envelope with the commercially available mechanised bolters. For this reason, bolts are installed with either jacklegs or CMAC support drill rigs. Support rib pillars are left in place as the stope retreats along strike to keep the hangingwall stable in areas mined through the sub-level extraction long hole stoping method. In general, low-grade areas of the reef excluded from mining provide additional regional pillar support. Mine personnel are appropriately trained to perform routine basic checks on ground support or changes in ground conditions as part of their daily inspection of the work areas. Internal and external Geotechnical Engineers are then requested to assess geotechnically complex areas. When necessary, Stillwater and East Boulder Mines engage the services of external consultants to provide geotechnical oversight functions related to ground support performance, stope performance and design. Both mines currently use a Trigger Action Response Plan (TARP) in regard to ground conditions and ground support. With progression from a TARP 1 to TARP 3, the plan is escalated to higher levels within the organisation for review. Support designs for the Benbow Decline which was completed in FY2021 in the Stillwater East Section incorporated primary development support designs employed at the Stillwater West Section and East Boulder Mine. The opening up of new areas in the Stillwater East Section has afforded the opportunity to assess actual ground conditions in this part of Stillwater Mine. A higher frequency of Type 3 ground 129 conditions and variants has been observed than expected, with the available geotechnical data indicating area split for Type 1&2 (fair and good), Type 3 (poor) and Type 3+ (very poor conditions) conditions of 50%, 25% and 25%, respectively. The Type 3 and 3+ ground types encountered have necessitated the use of cemented rock fill or the overhand ramp and fill method with extensive support, which have affected the development advance, mining cycles and the economics of mining in these areas. A fall of ground incident related to poor ground conditions was reported in a stope (5600E 18400). As a result, the establishment of a paste plant (SWE Paste Plant) in the Stillwater East Section in FY2027 has been prioritised in the LoM plan. It is anticipated that the use of paste-fill in areas of poor ground conditions will improve mining and cost efficiencies. The LoM plan has been updated to minimise mining Type 3 and 3+ ground types and prioritise Type 1 and 2 ground types (in the 5600E and 6000E Levels) until the SWE Paste Plant has been constructed. A dedicated support team has been established for the limited Type 3 and 3+ ground types that will be mined in the interim. Poor ground conditions have also been encountered in the Lower Off Shaft West and Lower Off Shaft East areas of the Stillwater West Section. In the former, the poor conditions are due to stress resulting from approximately 5 000ft of overburden (mountain apex). The stopes in this region are primarily mined using the underhand ramp and fill method with paste to mitigate the stress issues. Less stress is expected as the mining front progresses westwards in areas where the burden will reduce. As for the Lower Off Shaft East area, poor ground conditions occur in bounded by the Stillwater Valley Fault to the west and A-Fault to the east. The use of paste fill for support and the underhand ramp and fill method has historically allowed for mining in this area. East Boulder Mine has not experienced any significant ground events or changes in ground support methodology in recent years. In general, the mechanised ramp and fill mining method has widely been used, with sub-level long hole extraction performed after geotechnical analysis on potential stresses. Furthermore, sub-level long hole extraction is not used in the far west areas of East Boulder Mine where Type 3 ground conditions due to high stresses have been interpreted from field evaluations (Figure 22). The Qualified Person is of the view that the current rock reinforcement as prescribed in the ground control standards are adequate for mining throughout the LoM but will be reviewed and updated when necessary. The Qualified Persons are of the opinion that support designs for primary development and stopes utilised at Stillwater and East Boulder Mines for decades are appropriate for the ambient rock mass conditions encountered and mining methods used at both mines. A wealth of geotechnical data (Section 7.10) exists for the mines upon which appropriate stope sizes and support practices have been designed through detailed engineering. These support designs and operational practices have also been accounted for in the overall mine designs for the Stillwater East section of Stillwater Mine. However, a higher-than-expected frequency of poor ground conditions encountered in the Stillwater East Section necessitate expedited establishment of a paste plant in this area to improve mining cycles and efficiencies as well as the economics of mining in this area. 130 Surface and Subsidence Control Regulatory permits have been issued to Stillwater and East Boulder Mines by the Department of State Lands, State of Montana regarding the minimum size of crown pillar to be left from surface and the shallowest depth of stoping activities. These permits specify a 20ft to 50ft crown pillar of competent bedrock for mining below surface terrain that does not contain water courses otherwise a 200ft crown pillar of competent bedrock should be used. The Qualified Persons have confirmed that appropriately sized crown pillars have been incorporated in the mine designs for Stillwater and East Boulder Mines. Backfill 13.4.4.1 Overview Hydraulic sandfill comprising a coarse fraction of the tailings is the backfill used in most stopes mined through the mechanised ramp and fill method. However, cemented tailings paste is only used in stopes mined through the mechanised underhand ramp and fill method to provide sufficient backfill strength for support when this approach is employed. The use of tailings as backfill is also important for tailings volume reduction, with approximately 44% to 50% of the tailings material generated at Stillwater Mine and 46% to 48% of tailings generated at East Boulder Mine used as backfill. No additional steps are necessary to treat any tailings placed back into the mine. 13.4.4.2 Stillwater Mine For the Stillwater West Section, tailings from the Stillwater Concentrator scavenger circuit are pumped to the sandfill plants, where up to 60% is used in the mine backfill process (via the use of cyclones for segregation of -45µm material). A paste fill plant is situated on surface close to the portal from where paste is pumped into the mine via the 5150W from where it is then distributed to the workings requiring fill. The section also has three sandfill plants, with two (i.e., the 4900 Level and 5000 Level Sandfill Plants) situated close to the portal area and the third situated on the 5500W Level providing sandfill for the Upper West mining area. The supply of tailings to the 5500W Level Upper Sandfill Plant is passed through a booster pump in the 5500 Level Portal and cyclones to remove the fine fraction (-45µm) after which the coarse fraction is placed in storage silos. Sandfill is dispatched to the stopes requiring fill mainly by gravity to the Off Shaft mining areas and by high pressure positive displacement pumps for the workings above the 5000 Level; it should be noted that many levels can be serviced from more than one plant- either gravity fill from the 5500 Plant or high-pressure pump from the 5000 Plant. The fines fraction of the tailings is returned to surface via centrifugal pumps for storage at the TSF. To support the mechanised overhand ramp and fill mining in the Stillwater East Section, hydraulic sand backfill is delivered from the 5600E Sand Plant. A 4-inch sand delivery pipe installed from the 5000W pump to the Stillwater East Section serves as the main feed to the 5400E-10400 Sandfill Plant. The Qualified Person notes that Sibanye-Stillwater is currently engaged in an engineering study to deliver thickened tails to the Stillwater East Section for the production of paste for use in mechanised underhand ramp and fill stoping blocks that have poor ground conditions. It is anticipated that a dedicated paste plant for this section will be commissioned in FY2027.


131 13.4.4.3 East Boulder Mine Stopes at East Boulder Mine are backfilled with whole mill tailings delivered from the East Boulder Concentrator on surface to an underground sand plant located on the 6500 Level from where the sandfill is distributed by booster pumps to two other sandfill plants on the 7200 Level and 8200 Level. Similar to Stillwater Mine, the tailings material is pumped through cyclones to remove the fine fraction and the coarse fraction is placed in six underground storage silos while the fine fraction is returned to surface via centrifugal pumps for storage at the tailing storage facility (TSF). Sandfill is dispatched to the stopes requiring fill by positive displacement pumps. All decant and flush water reports into the mine wastewater system, which reports to the main pump station on the 6450 Level. Stillwater Mine Operations Background Established in 1986, Stillwater Mine has produced approximately 60 000 tons of RoM ore per month from a single section – the Stillwater West Section – with the RoM ore processed at the onsite concentrator. A planned step change in production output to approximately 106 000 ton per month necessitated mine expansion into the Blitz area – the Stillwater East Section. Development of the Stillwater East Section (i.e., the Blitz Project) commenced in 2011 with the excavation of access adits and this has been ongoing to date. Development of the capital infrastructure (access drifts, decline and ramps, and ventilation shafts) required in the Stillwater East Section was completed in FY2022. The combined monthly ore production from Stillwater Mine after the inclusion of output from the Stillwater East Section from late FY2017 has gradually been ramping up until a peak of 80 000 tons in FY2020 before the ramp up pace was interrupted by the COVID-19 pandemic restrictions in 2021 to 2022, access restrictions due to the 2022 500-year flood event and a shaft incident (i.e. structural damage to the shaft headgear, winder house and winder rope preventing access to production areas below the 5000 Level for four weeks and disrupting the mine’s ability to haul rock out below 5000W by eight weeks) in the Stillwater West Section in FY2023. The production ramp up is planned to resume in 2024 towards a steady state monthly production level of approximately 100 000 tons (1.2 million tons per annum) by approximately FY2029 and thereafter. Key Operational Infrastructure Stillwater Mine includes the mining operations and ancillary buildings that contain the concentrator, workshop and warehouse, changing facilities, headframe, hoist house, paste plant, water treatment, storage facilities and offices. All surface infrastructure and TSFs are located within the Stillwater Mine Operating Permit, which covers an area measuring 2 450 acres. Stillwater Mine has developed an approximately 9-mile-long segment of the J-M Reef encompassing the Stillwater West and East Sections in the eastern part of the Stillwater Complex. Mine Layout The underground mine layout for Stillwater Mine is illustrated in Figure 54 and this also shows the final mine outline. 132 The Stillwater West Section has been divided into three large mining areas, namely the Off-shaft, Upper West and Lower Far West areas, using geological domain boundaries. These domains have been subdivided into mining blocks as follows (Figure 9):  Block 1 and Block 2 in the Upper West area, which is above the 5000 Level in the Dow Sector;  Blocks 1 and 2 in the Lower Far West area, which is below the 5000 Level in the Dow Sector;  Blocks 3 and 6 in the Off Shaft West area; and  Blocks 7 and 8 in the Off Shaft East area. The Stillwater East Section has been divided into two large mining areas, namely Blitz West and Blitz. 13.5.3.1 Stillwater West Section Access to the reef in the Stillwater West Section is by means of an approximately 2 000ft Vertical Shaft and a system of horizontal adits and drifts driven parallel to the strike of the J-M Reef at vertical intervals of between 150ft and 400ft. Ten main adits have been driven from surface portals on the west and east slopes of the Stillwater Valley at various elevations between 5 000ft and 5 900ftamsl. Five principal levels have been developed below the valley floor by ramping down from the 5 000ft level to extract ore from the J-M Reef down to the 3 800ftamsl elevation. Five additional major levels below the 5 000ft level are accessed principally from the vertical shaft and shaft ramp system. The mine has developed a decline system from the 3 200ft elevation to access and develop deeper areas in the central part of the mine below those currently serviced by the existing shaft. The decline system currently accesses the 2900, 2600, 2300, 2000, 1700 and 1600 Levels. It was the objective to keep these footwall developments approximately 100ft to 150ft from the J-M Reef, so that a fan of diamond drillholes could be drilled across the J-M Reef at 50ft intervals. The footwall laterals were originally driven on 200ft vertical intervals, but this spacing was increased to 400ft due to the dip of the hangingwall being similar to the Stillwater East Section which allows for the 400ft vertical section to be drilled from a single FWL. The Vertical Shaft system provides access to the workings below 5000W Level. It serves as a conduit for the transport of men and materials while also hoisting broken rock (ore and waste) to surface. The Stillwater West Section currently uses its 300ft spaced laterals, six primary ramps and vertical excavations to provide personnel and equipment access, supply haulage and drainage, intake and exhaust ventilation systems, muck haulage, backfill plant access, powder storage and/or emergency egress. The footwall lateral and primary ramp systems will continue to provide support to production and ongoing development activities. In addition, certain mine levels are required as an integral component of the ventilation system and serve as required intake and or exhaust levels, or as parallel splits to maintain electrical ventilation horsepower balance and to meet the Mine Safety and Health Administration (MSHA) Regulations. MSHA Regulations also contain requirements for alternate (secondary) escape-ways from mine workings and these levels also meet this need. These levels serve as permanent mine service-ways and are used for road and rail transportation, dewatering and backfill pumping facilities. 133 13.5.3.2 Stillwater East Section The Stillwater East Section is currently under development, with footwall lateral level spacing of 400ft being used. The 5000E TBM drift serves as the main access to this section and this is being driven 600ft south of the JM-Reef. It is a dedicated haulage-ventilation drive and not a normal FWL. Therefore, the drive has also been equipped with rails and serves as the main gathering haulage where ore and waste are transported out of the mine using trains. The development of the 5600E Footwall Drive, which is positioned 600ft above the 5000E Footwall Drive, is currently ongoing. This drive provides access to the stoping blocks. In the eastern part of the Stillwater East Section, the Benbow Decline has also intersected the 5600E Footwall Drive for the provision of additional egress access and as a ventilation intake. The first holing with the 5600E Level from the western portion of the Stillwater East Section was completed in Q3 FY2022. East Boulder Mine Operations Background East Boulder Mine was established in 1997 and started producing ore in 2002 at approximately 55 000 tons per month. In 2016, the steady state monthly RoM ore production level for East Boulder Mine was planned to be approximately 65 000 tons per month after ramping up from the historical levels which were lower than 54 000 tons in line with the Fill the Mill Project which was implemented to utilise the historically unused capacity of the East Boulder Concentrator. During FY2020, several key elements required to increase production levels and take advantage of the unused mill capacity were put in place. The 72 740-production ramp system was developed, and production mining was initiated. An incline was developed to meet the existing Frog Pond Adit which serves as both a ventilation path to surface as well as a secondary egress with a surface shelter. In Q3 FY2020, the Fill the Mill project was completed. Monthly production out rose from approximately 54 000 tons in FY2017 to FY60 000 tons in 2021. The production ramp up momentum reversed in FY2022 to approximately 45 000 tons per month due to the COVID-19 pandemic restrictions and associated operational factors but remained at 47000 tons per month in FY2023. According to the current LoM plan, mining output will ramp up to the revised steady state level of approximately 53 000-63 000 tons per month in FY2024, which is equivalent to approximately 631 000-760 000- tons per annum. Key Operational Infrastructure East Boulder Mine includes the underground mining operations and surface support facilities such as the concentrator, workshop and warehouse, changing facilities, water treatment, storage facilities, office and TSF. All surface infrastructure and the TSF are located within the East Boulder Mine Operating Permit, which covers an area measuring 1 000 acres. East Boulder Mine has developed an approximately 5- mile-long segment of the J-M Reef encompassing the Frog Pond East and West Sections in the western part of the Stillwater Complex. 134 Mine Layout The underground mine layout for East Boulder Mine is illustrated in Figure 54 and this also shows the final mine outline. The predominant mining method is mechanised overhand ramp and fill method complemented by limited sub-level extraction long hole stoping. The J-M Reef at East Boulder Mine is accessed by two access drives, each 3.5 miles long and 15ft in diameter, developed perpendicular to reef strike to intersect the J-M Reef from the north. The access tunnels from surface intersect the reef at an elevation of 6 450ftamsl. Footwall haulages have been developed east and west from this intersection point to open the strike extent of the deposit. The stopes are accessed up-dip by ramps and footwall lateral drifts on 200ft to 400ft vertically spaced levels located approximately 150ft to 200ft from the J-M Reef. Measured Mineral Resources converted to Proved Mineral Reserves are delineated by definition diamond core drilling from these headings, which are also used for stope access and development. The current mine occupies a 5-mile-long footprint which is 2 300ft in vertical extent. The mine plan anticipates the 9400 Level to be the ultimate upper level in the mine. The main adit haulage level is the 6500 Level with the 670 Ramp system having been developed to the 9100 Level. Except for the adit rail haulage, the mine is operated as a trackless mining operation. The 6500 Level footwall haulage extends laterally for a nominal 21 000ft, and the 6700 Level footwall haulage extends laterally for a nominal 18 000ft. The levels are connected by spiral ramps and the reef is accessed by crosscuts. Between 2010 and 2015, the west end of the 6500 Level was extended further west to the Graham Creek area to connect to the Graham Creek vertical raise.


135 Figure 54: Generalized Underground Layouts for Stillwater and East Boulder Mines Showing Final Mine Outlines 136 Life of Mine Planning and Budgeting Introduction The Mineral Reserves for Stillwater and East Boulder Mines are reported from LoM production schedules, which have been tested for economic viability. Stillwater Mine will produce ore from the mature Stillwater West Section and the Stillwater East Section under development. Stillwater Mine is forecast to attain steady state production by FY2029 and operate at this level until end of the LoM in 2054. The LoM plan has emphasised underground primary and infrastructure development in all regions of the Stillwater West Section to access more higher-grade mineralised zones and improve productivity. The introduction of a paste plant (SWE Paste Plant) in the Stillwater East Section is also a key area of focus in the LoM plan as the use of paste-fill in areas of poor ground conditions will improve mining conditions and cost efficiency. East Boulder Mine will produce ore concurrently from the mature higher-grade Frog Pond West Section and lower-grade Frog Pond East Section. East Boulder Mine is forecast to operate at the revised steady state production level from FY2027 until FY2068, thereafter reducing for the remainder of the LoM (FY2069). Stabilising the workforce and developing surface expansion projects (e.g. TSF expansion) are strategic areas of focus for the LoM plan. Stillwater and East Boulder Mines utilise the DeswikTM suite of mine design and scheduling software. Both mines use a common approach to LoM planning whereby each identified stoping block is scheduled in terms of forecast ore tonnage, waste tonnage and head grade for the LoM plan. In addition, the scheduling process accounts for the following:  Mineral Resource tons and grades;  Dilution;  Stoping tons generated per Miner per month;  In-stope development rates and ore generated per month;  Primary development rates and waste generated per month; and  Secondary development rates and waste generated per month. Different approaches were followed for the scheduling of Indicated and Measured Mineral Resources to derive the LoM production schedules for each mine. The differences in approach were necessitated by the differences in geological confidence for Indicated and Measured Mineral Resources. For the conversion of Measured Mineral Resources to Proved Mineral Reserves, the high abundance of geological information available to accurately constrain thickness, tonnage and grades and the accuracy of technical and cost inputs permit the compilation of estimates to a level of accuracy of within ±15% (Feasibility Study level of accuracy). For the conversion of Indicated Mineral Resources to Probable Mineral Reserves, the sparse geological information limits the confidence in the estimates. As a result, the conversion relies on statistics on key metrics extrapolated from the Proved Mineral Reserve areas per domain and mining block. The Mineral Reserves in these Indicated Mineral Resource areas are defined to a lessor level of accuracy of within ±25% (Preliminary Feasibility Study level accuracy). Mine Planning Criteria The Stillwater West Section carries out approximately 40 000ft of primary and secondary development per annum while the Stillwater East Section is currently developing 15 000ft annually as it expands to the east. Currently, the mining footprint at Stillwater Mine spans approximately 45 000ft of strike length. LoM 137 planning and scheduling criteria for stoping and development are summarised in Table 30 and Table 31. Table 30: Planning Parameters for Stoping for Stillwater Mine Mining Method Stoping Parameters Total Tons Per Miner Per Month Percentage Ore Mining Method Mix Mechanised Ramp and Fill 323 84% 88% Sub-level Extraction 367 100% 12% Table 31: Planning Parameters for Primary Development for Stillwater Mine Area Development Parameters Advance Factor Number of Crews Advance Feet Per Month Tons Per Foot Stillwater West 0.96 7 266 13 Stillwater East 0.96 3 130 18 East Boulder Mine conducts approximately 20 000ft of primary and secondary development per annum to expand the mining and Mineral Reserve footprints. LoM planning and scheduling criteria for stoping and development are summarised in Table 32 and Table 33. All data utilised in the development of the LoM schedule is based on historical data gathered since the inception of the mines. Table 32: Planning Parameters for Stoping for East Boulder Mine Mining Method Stoping Parameters Total Tons Per Miner Per Month Percentage Ore Mining Method Mix Mechanised Ramp and Fill 567 90% 80% Sub-level Extraction 708 100% 20% Sub-level Development 567 85% 0% Table 33: Planning Parameters for Primary Development for East Boulder Mine Area Development Parameters Advance Factor Number of Crews Advance Feet Per Month Tons Per Foot Frog Pond West 0.95 1 60 14 Frog Pond East 0.95 1 60 14 Lower Frog Pond East 0.90 1 60 14 Lower Frog Pond West 0.90 1 60 14 Historical analysis of mine planning and production data revealed that a recovery factor was required to reconcile blasted and removed tons in the sub-level extraction stopes in the Upper West area of the mine. The historical production data indicated that 25% of the broken material was not recovered from these mining areas. Both the HoverMap and LIDAR scan data of more than 100 stopes have also confirmed this under recovery. Therefore, a 75% recovery factor was applied to all sub-level extraction tons and ounces since December 2005. In recent years there has been a reduction in sub-level extraction grade at Stillwater and East Boulder Mines. A reconciliation between mill reconciled sub-level extraction and Mineral Reserve data for a 12- month period showed mining recovery of 100% of the sub-level extraction tons but at a lower grade than planned. A mining recovery factor of 75% has been applied to the sub-level extraction design grade, with 100% of the tons being reported implying a 25% grade reduction factor. At East Boulder Mine, reconciliation between panel designs and Hovermap scans in 2021 and 2022 respectively show 138 49% and 62% average dilution above panel design tons. A 25% grade reduction factor was applied to lower the Mineral Reserve grade. The technical teams remained focused on reducing these lost tons through modifying blasting practices. The unit dimensions for each stope block varies depending on lateral spacing (300ft to 400ft), reef width, economic (pay) strike length, rib and sill pillar requirements. The stope unit dimension is finalised during the mine design and scheduling process. The typical mechanised ramp and fill stope design illustrated in Figure 55 indicates that the total height is 300ft, inclusive of sill pillars, with an overall extraction length of 2 000ft and at a minimum mining width of 8ft. Figure 55: Typical Mechanised Ramp and Fill Stope Design Modifying Factors 13.7.3.1 Introduction The technical (mining and survey) modifying factors employed in the conversion of Mineral Resources to Mineral Reserves through a LoM design and scheduling process are reviewed annually and adjusted appropriately by the Qualified Persons based on historical mine production reconciliation and tons and grade delivered to mill. Several key improvements are being implemented at the mines to refine the mine to mill reconciliation process and increase the granularity of the data to better constrain the modifying factors, particularly dilution and deletion. These improvements include the weighing of all muck reporting to surface from the different areas of the mine, 3D digital mapping of all headings and LIDAR scanning of all production headings after mining. Stillwater and East Boulder Mines have completed reconciliation studies to attempt to more accurately quantify the modifying factors employed for the conversion of Mineral Resources to Mineral Reserves, namely dilution, Mine Call Factor and deletion, and to more accurately report the expected tons and head grade delivered to the concentrator. The Qualified Persons approved the modifying factors employed for the development of the LoM plans for Stillwater and East Boulder Mines.


139 13.7.3.2 Mining Dilution Dilution factors applied for the conversion of Mineral Resources to Mineral Reserves are based on historical reconciliation for each mining method and results of the recent studies reviewing the modifying factors. Based on historical data, a dilution factor has been introduced which is the amount of material added to the ore at zero grade during stoping operations. For example, 15% more tons than planned in the case of Dow UG Upper are added to the ore tons delivered to the concentrator at an assumed 2E grade of 0opt. The result is that 15% more ore tons are delivered to the concentrator but at a lower head grade. Table 34 summarises the dilution factors and methodology utilised in the Mineral Resource to Mineral Reserve conversion for the mechanised ramp and fill and sub-level extraction mining methods in each of the sub-areas at Stillwater Mine. While Mineral Resources are reported at a single minimum mining width (MMW) of 7.5ft given the predominance of the mechanised ramp and fill method at Stillwater and East Boulder Mines, a different approach to the application of the minimum mining width was followed for mine planning. Instead of using the diluted block model employed for Mineral Resource estimation, which assumes 100% mining via the mechanised ramp and fill method, the original undiluted (channel) block model for the reef channel was used. To the channel block model, minimum mining widths adjustments based on the mining method per reef domain were applied in the Proved Mineral Reserve areas. The minimum mining widths set a standard for the best-case recovery of a Mineral Reserve for a given mining method and stope location, which can be used to measure mining performance. An extra 1.5ft hangingwall and footwall dilution is added to the ore width for areas mined using the 2.0-cubic yard LHDs but an extra 1.0ft of dilution was added for all other mining methods. In addition, if the ore width plus the extra dilution is less than or equal to the applicable minimum mining width, then the diluted width would be equal to the minimum mining width, but if the ore width plus the extra dilution is greater than the minimum mining width then the diluted width would be adopted. Since 2020, additional dilution has been added to the Mineral Reserve at Stillwater Mine, on top of the best-case recovery. This dilution was added by reef domain with the goal of aligning the Proved Mineral Reserve grade with the mill head grade. The dilution is shown in Table 34. Table 34: Mining Dilution Factors and Dilution Methodology for Stillwater Mine Domain Equipment/Process Horizontal Width (ft) True Width (ft) Dilution (%) Deletion (%) Off Shaft West Upper 1.5yd LHD – Ramp and Fill 7.4 6.5 15 16 2yd LHD – Ramp and Fill 8.5 7.5 15 16 4yd LHD – Ramp and Fill 12.0 10.6 15 16 Sub-level Extraction 5.1 4.5 15 9 Off Shaft West Lower 1.5yd LHD – Ramp and Fill 7.4 6.5 15 16 2yd LHD – Ramp and Fill 8.5 7.5 15 16 4yd LHD – Ramp and Fill 12.0 10.6 15 16 Sub-level Extraction 5.1 4.5 15 9 Off Shaft East- West 1.5yd LHD – Ramp and Fill 7.4 6.5 15 16 2yd LHD – Ramp and Fill 8.5 7.5 15 16 4yd LHD – Ramp and Fill 12.0 10.6 15 16 Sub-level Extraction 5.1 4.5 15 9 140 Domain Equipment/Process Horizontal Width (ft) True Width (ft) Dilution (%) Deletion (%) Off Shaft East- East 1.5yd LHD – Ramp and Fill 7.0 7.0 15 16 2yd LHD – Ramp and Fill 7.5 7.5 15 16 4yd LHD – Ramp and Fill 12.0 12.0 15 16 Sub-level Extraction 5.0 5.0 15 9 Blitz West 1.5yd LHD – Ramp and Fill 7.2 6.5 15 16 2yd LHD – Ramp and Fill 8.3 7.5 15 16 4yd LHD – Ramp and Fill 12.0 10.9 15 16 Sub-level Extraction 5.0 4.5 15 9 Blitz 1.5yd LHD – Ramp and Fill 6.7 6.5 15 16 2yd LHD – Ramp and Fill 7.8 7.5 15 16 4yd LHD – Ramp and Fill 12.0 11.6 15 16 Sub-level Extraction 4.7 4.5 15 9 Upper West East 1.5yd LHD – Ramp and Fill 7.5 6.0 15 16 2yd LHD – Ramp and Fill 9.4 7.5 15 16 4yd LHD – Ramp and Fill 12.0 9.6 15 16 Sub-level Extraction 5.0 4.0 15 9 Dow Upper 1.5yd LHD – Ramp and Fill 7.9 5.5 15 16 2yd LHD – Ramp and Fill 10.8 7.5 15 16 4yd LHD – Ramp and Fill 12.0 8.3 15 16 Sub-level Extraction 5.0 3.5 15 9 Dow Lower 1.5yd LHD – Ramp and Fill 7.9 5.5 15 16 2yd LHD – Ramp and Fill 10.8 7.5 15 16 4yd LHD – Ramp and Fill 12.0 8.3 15 16 Sub-level Extraction 5.0 3.5 15 9 Table 35 presents the dilution factors and methodology for the two mining methods used at East Boulder Mine. This also shows the minimum horizontal width for the mechanised ramp and fill and the sub-level extraction methods. A total of 10% of unplanned hangingwall and footwall overbreak (dilution) is added to either of the minimum horizontal widths in respect of the mechanised ramp and fill mining method whereas no unplanned dilution is anticipated in areas mined through the sub-level extraction method. Table 35: Mining Dilution Factors and Dilution Methodology for East Boulder Mine Domain Method Minimum Horizontal Width (ft) True Width (ft) Dilution (%) Deletion (%) Frog Pond East and West Sub-level Extraction 6.5 5.0 0 5 Mechanised Ramp and Fill 9.8 7.5 10 7 13.7.3.3 Deletion Deletion is applied to account for the loss in 2E ounces between the planned stopes and surface RoM stockpile feeding the concentrator. The two most common sources of deletion related to ore left on the floor of the stope and when reef material is left in situ when the actual stope shape deviates from the planned shape. The recent mine production reconciliation studies concluded that the loss in metal ounces is approximately 9% for sub-level extraction stopes and 16% for mechanised ramp and fill stopes at Stillwater Mine and 5% for sub-level extraction stopes and 7% for mechanised ramp and fill stopes at East Boulder Mine as shown in Table 34 and Table 35. These are the deletion factors applied to all blocks 141 across Stillwater and East Boulder Mines. Deletion will be monitored and revised annually when necessary. 13.7.3.4 Low Grade Reef Material It is common practice at both Stillwater and East Boulder Mines to ship material to the concentrator that is below the cut-off grade for high-grade ore when there is excess hoisting and milling capacity. This low-grade reef material (internally referred to as reef sand) is mined to access high-grade reef material. The low-grade and high-grade reef material is hoisted and milled together when there is sufficient hoisting and milling capacity. At East Boulder Mine, the 2E cut-off grade for the dominant mechanised ramp and fill stopes is 0.05opt and this aligns the head grade and tonnage of material milled and the Mineral Reserves; the 2E cut-off grade for the few sub-level extraction stopes is 0.20opt. At Stillwater Mine, reconciliation data indicates that the low-grade material has an average 2E grade of 0.12opt constitutes approximately 9% of the milled tonnage. However, the low-grade material was excluded from the LoM plan underlying the Mineral Reserves for Stillwater Mine due to the use of a higher 2E cut-off grade of 0.2opt in the Dow Upper and Dow Lower block models and 0.3opt in the rest of the mine. In future following the commissioning of the additional mill capacity at Stillwater Mine, the Qualified Person will reassess the necessity for lowering the 2E cut-off grade for Mineral Reserve reporting to improve alignment between the head grade and tonnage of material milled and the Mineral Reserves. 13.7.3.5 Tonnage Shortfall Factor A 4% tonnage shortfall factor was accounted for in the Proved and Probable Reserve tonnages for Stillwater Mine. The shortfall factor represents ore left behind in the sill that is not cleaned out and ore that was identified in the ribs, but not mined. The shortfall factor reduces tons and ounces in the Mineral Reserves, but the grade is unaffected by the application of this factor. 13.7.3.6 Mine Call Factor At this stage, no Mine Call Factors were applied to the Mineral Reserves as the loss in ounces between the stopes and the surface RoM stockpile is ascribed to deletion. Future mine to mill reconciliations at Stillwater and East Boulder Mines will establish Mine Call Factors at each of the sites which will be utilised for mine planning. Indicated Mineral Resources to Probable Mineral Reserves Conversion Factors The mineability block factor (MBF), which is calculated in the definition drilled areas, is integral to the estimation of Probable Mineral Reserves. MBFs for the various reef domains are derived from a comprehensive mine reconciliation process at Stillwater and East Boulder Mines. A MBF is calculated as the percentage of the fully diluted ore grade tonnage within a mineable area compared with the total fully diluted ore grade tonnage within the boundary area of a block or percent of material historically extracted from the block. The mineable area within a block is the area that has been mined out, is within the active stopes or has sufficient grade and continuity that it should have been or will be mined. An adjustment is made to the percentage determined to compensate for negative or positive tonnage 142 and metal ounce balances determined from historical stope reconciliation. The MBFs are used to perform adjustments of estimates when converting Indicated Mineral Resources to Probable Mineral Reserves. The final MBFs for each block shown in Table 36 reduced the final Probable Mineral Reserve yield in ore tons per foot of footwall lateral. Table 36: Mineability Block Factors for Stillwater and East Boulder Mines Mine Block MBF Stillwater Dow UG Upper 63% Dow UG Lower 58% Block-1 Upper 71% Block-1 Lower East 32% Block-1 Lower West 70% Block-2 27% Block-3 45% Block-6 53% Block-7 46% Block-8 40% Blitz West 25% Blitz 64% East Boulder Frog Pond East 70% Frog Pond West 70% Once the development and stope designs and layouts have been established in the Indicated Mineral Resource areas, Proved Mineral Reserve model statistics are applied for the derivation of production scheduled for Probable Mineral Reserve areas per block and domain. The following Proved Mineral Reserve model statistics are used:  Yield in ore tons per foot of footwall lateral driven;  Yield in ounces per foot of footwall lateral driven; and  Grade in ounces per ton. The block and domain specific statistics are applied to respective Probable Mineral Reserve blocks for which there are development designs and high-level stope outlines to estimate the Probable Mineral Reserve tonnages and grades. Life of Mine Production Scheduling and Budgeting Process Overview A formalised LoM production scheduling and budgeting process is followed for the Sibanye-Stillwater US PGM Operations, paying attention to the integrated nature of the operations. The LoM production schedules for Stillwater and Easter Boulder Mines are tested for economic viability before being aggregated for Mineral Reserve reporting. The LoM production scheduling focuses on primary access (lateral) development design and scheduling and stope design and scheduling. Each stope is evaluated in terms of a proposal, which also contains reef access and stope designs, production schedules and results of the economic


143 assessments completed. Only the stopes that are associated with positive economic outcomes are included in the aggregate LoM production schedule for each mine. The key elements accounted for in the development, stope and loM production scheduling and budgeting processes include the following:  Milling days;  RoM ore tonnage and contained 2E metal content;  RoM ore 2E grade;  Low-grade ore (reef sand) tonnage milled;  Backfill placed;  Mining method splits with tonnages and grade;  Primary development required;  Secondary development required;  Development tonnage broken;  Total tonnage broken (ore and waste); and  Tonnage to be milled (feed). The data (tonnage, grade and development) generated by the scheduling process feeds into the Xeras system for the development of cost budgets. The budgets account for all costs associated with mining, processing, engineering maintenance, site overheads and all capital costs associated with primary development and mine-based projects. These budgets are then accounted for in the LoM Financial Model employed for the economic viability testing of the LoM plans. LoM Production Schedule for Stillwater Mine Table 37 and Figure 56 present the LoM production schedule for Stillwater Mine to FY2054. Figure 56 shows the production ramp up associated with increased output from mainly the Stillwater East Section from FY2026 to FY2029. Production is maintained at the steady state level until FY2052 after which there is reduction in tonnage in FY2053 and FY2054. The reduction is due to depletion of the currently scheduled Measured and Indicated Mineral Resources included in the LoM production schedule for Stillwater Mine. As shown in Table 22, there is a significant proportion of Indicated and Measured Mineral Resources not scheduled for mining in the current LoM plan available for LoM extension, when required. Sustained additional definition drilling will be required to upgrade parts of the Indicated Mineral Resources to Measured Mineral Resources included in the production schedule while the unscheduled remnant Measured Mineral Resources left in the historically mined areas can potentially be brought into the production schedule at insignificant capital expenditure, when required and subject. A 10% 2E grade improvement from the average of 0.39opt to a new average of 0.45opt is also noticeable from FY2027 onwards as the mine approaches the steady state production level and high- grade ore production matches concentrator capacity. The grades reflected in Table 37 and Figure 56 incorporate the impact of the conservative approach of using a 100% ore percentage and the grade reduction factor discussed in Section 13.7.2 adopted in the conversion of Mineral Resources to Mineral Reserves. 144 Table 37: LoM Production Schedule for Stillwater Mine Figure 56: LoM RoM ore production schedule for Stillwater Mine Based on the historical performance at Stillwater Mine and considering the available mining equipment fleet for the Stillwater Mine, the Qualified Person is of the opinion that the LoM production plan is achievable. The LoM production schedule includes the scheduled Measured and Indicated Mineral Resources and excludes Inferred Mineral Resources. Life of Mine Production Schedule for East Boulder Mine Table 38 and Figure 57 present the LoM production schedule for East Boulder Mine to FY2069. Figure 57 also shows production targets from FY2024 to FY2068 planned at levels achieved in FY2021 after completion of the Fill The Mill Project. Production ceases after a reduction in FY2069. With some modest capital expenditure, there are unscheduled Measured and Indicated Mineral Resources reflected in Table 22 which can be brought into the LoM production schedule to main production at the steady FY2021 FY2022 FY2023 FY2024 FY2025 FY2026 FY2027 FY2028 FY2029 FY2030 FY2031 FY2032 Mill Feed Tons 898 229 746 956 728 560 782 359 777 832 930 205 982 715 1 109 772 1 179 270 1 200 093 1 199 806 1 200 489 Feed 2E Content (oz) 381 327 285 838 279 207 303 261 303 599 377 459 437 352 498 787 536 322 547 856 562 478 555 299 Returnable 2E Content (oz) 346 557 260 206 239 393 276 549 276 733 344 027 397 921 454 202 489 309 499 275 515 085 509 492 Feed 2E Grade (opt) 0.42 0.39 0.38 0.39 0.39 0.41 0.45 0.45 0.45 0.46 0.47 0.46 FY2033 FY2034 FY2035 FY2036 FY2037 FY2038 FY2039 FY2040 FY2041 FY2042 FY2043 FY2044 Mill Feed Tons 1 199 978 1 199 360 1 200 990 1 200 231 1 198 986 1 200 637 1 199 549 1 198 752 1 200 051 1 199 820 1 200 820 1 199 872 Feed 2E Content (oz) 548 078 541 060 545 671 542 305 538 897 533 829 538 272 540 822 520 645 518 209 537 194 542 267 Returnable 2E Content (oz) 502 245 495 265 499 585 497 625 494 227 488 557 492 074 494 497 475 578 473 200 491 188 496 765 Feed 2E Grade (opt) 0.46 0.45 0.45 0.45 0.45 0.44 0.45 0.45 0.43 0.43 0.45 0.45 FY2045 FY2046 FY2047 FY2048 FY2049 FY2050 FY2051 FY2052 FY2053 FY2054 Mill Feed Tons 1 203 718 1 199 573 1 201 232 1 199 847 1 199 641 1 199 983 1 200 282 1 199 816 1 131 245 475 596 Feed 2E Content (oz) 535 329 523 484 527 887 522 492 536 474 531 111 579 876 556 019 588 909 252 021 Returnable 2E Content (oz) 490 641 478 375 482 421 478 053 491 071 485 967 531 009 508 824 541 383 231 682 Feed 2E Grade (opt) 0.44 0.44 0.44 0.44 0.45 0.44 0.48 0.46 0.52 0.53 Parameter Actual Parameter Parameter Budget Budget Bdget 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0 200 000 400 000 600 000 800 000 1 000 000 1 200 000 1 400 000 FY 2 0 2 1 FY 2 0 2 2 FY 2 0 2 3 FY 2 0 2 4 FY 2 0 2 5 FY 2 0 2 6 FY 2 0 2 7 FY 2 0 2 8 FY 2 0 2 9 FY 2 0 3 0 FY 2 0 3 1 FY 2 0 3 2 FY 2 0 3 3 FY 2 0 3 4 FY 2 0 3 5 FY 2 0 3 6 FY 2 0 3 7 FY 2 0 3 8 FY 2 0 3 9 FY 2 0 4 0 FY 2 0 4 1 FY 2 0 4 2 FY 2 0 4 3 FY 2 0 4 4 FY 2 0 4 5 FY 2 0 4 6 FY 2 0 4 7 FY 2 0 4 8 FY 2 0 4 9 FY 2 0 5 0 FY 2 0 5 1 FY 2 0 5 2 FY 2 0 5 3 FY 2 0 5 4 Fe e d 2 E G ra d e ( o p t) M ill F e e d ( To n s) Mill Feed Tons Feed 2E Grade (opt) 145 state level or to extend the LoM. In addition, sustained additional underground definition drilling will permit the upgrade of Inferred Mineral Resources and allow sustained production at the steady state level beyond FY2049. Table 38: LoM Production Schedule for East Boulder Mine Figure 57: LoM Production Schedule for East Boulder Mine Given the quantity of unscheduled Inferred Mineral Resources at East Boulder Mine, it is reasonable to expect that the definition drilling will permit the upgrading of significant Inferred Mineral Resources and subsequent conversion to Mineral Reserves. Another key attribute of the production profile is the FY2021 FY2022 FY2023 FY2024 FY2025 FY2026 FY2027 FY2028 FY2029 FY2030 FY2031 FY2032 FY2033 FY2034 FY2035 FY2036 FY2037 Mill Feed Tons 720 953 545 873 565 820 631 438 647 381 638 411 686 999 686 999 686 999 686 999 686 999 686 999 686 999 671 059 714 577 678 052 687 946 Feed 2E Content (oz) 248 473 178 471 190 623 204 535 204 480 216 877 239 399 239 399 239 399 239 399 239 399 239 399 239 399 243 043 243 334 236 887 237 420 Returnable 2E Content (oz) 223 842 160 925 164 349 184 766 184 717 195 915 216 260 216 260 216 260 216 260 216 260 216 260 216 260 219 552 219 815 213 991 214 473 Feed 2E Grade (opt) 0.34 0.33 0.33 0.32 0.32 0.34 0.35 0.35 0.35 0.35 0.35 0.35 0.35 0.36 0.34 0.35 0.35 FY2038 FY2039 FY2040 FY2041 FY2042 FY2043 FY2044 FY2045 FY2046 FY2047 FY2048 FY2049 FY2050 FY2051 FY2052 FY2053 FY2054 Mill Feed Tons 683 703 717 100 717 897 723 526 739 637 760 135 747 742 745 203 744 689 730 002 721 627 708 004 639 872 702 868 714 501 688 929 694 608 Feed 2E Content (oz) 236 277 234 410 230 246 236 669 239 466 240 638 238 341 241 038 238 597 233 056 232 147 235 460 213 543 232 196 232 869 232 062 229 963 Returnable 2E Content (oz) 213 440 211 753 207 992 213 795 216 321 217 380 215 304 217 741 215 536 210 530 209 709 212 702 192 903 209 754 210 362 209 633 207 736 Feed 2E Grade (opt) 0.35 0.33 0.32 0.33 0.32 0.32 0.32 0.32 0.32 0.32 0.32 0.33 0.33 0.33 0.33 0.34 0.33 FY2055 FY2056 FY2057 FY2058 FY2059 FY2060 FY2061 FY2062 FY2063 FY2064 FY2065 FY2066 FY2067 FY2068 FY2069 Mill Feed Tons 643 795 675 016 719 184 681 280 698 783 671 549 677 236 674 942 655 452 699 749 721 315 739 214 728 286 747 472 405 497 Feed 2E Content (oz) 211 934 223 655 238 262 225 976 237 230 235 707 237 206 233 969 232 513 237 949 236 569 237 672 233 959 236 433 134 656 Returnable 2E Content (oz) 191 450 202 039 215 233 204 135 214 302 212 925 214 280 211 355 210 040 214 951 213 704 214 700 211 346 213 581 121 641 Feed 2E Grade (opt) 0.33 0.33 0.33 0.33 0.34 0.35 0.35 0.35 0.36 0.34 0.33 0.32 0.32 0.32 0.33 Parameter Parameter Parameter Actual Budget Budget Budget 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0 100 000 200 000 300 000 400 000 500 000 600 000 700 000 800 000 FY 2 0 2 1 FY 2 0 2 3 FY 2 0 2 5 FY 2 0 2 7 FY 2 0 2 9 FY 2 0 3 1 FY 2 0 3 3 FY 2 0 3 5 FY 2 0 3 7 FY 2 0 3 9 FY 2 0 4 1 FY 2 0 4 3 FY 2 0 4 5 FY 2 0 4 7 FY 2 0 4 9 FY 2 0 5 1 FY 2 0 5 3 FY 2 0 5 5 FY 2 0 5 7 FY 2 0 5 9 FY 2 0 6 1 FY 2 0 6 3 FY 2 0 6 5 FY 2 0 6 7 FY 2 0 6 9 FY 2 0 7 1 Fe e d P d + P t G ra d e ( o p t) M ill F e e d ( To n s) Mill Feed Tons Feed 2E Grade (opt) 146 consistency in 2E grades (LoM average 2E grade of approximately 0.33opt), which reflects less grade variability compared to Stillwater Mine. The forecast 2E head grades are also aligned to the three-year actual average of 0.33opt. The Qualified Person considers the forecast production levels achievable as mining equipment and manpower required to meet the increased development and stoping requirements is available at the mine and the forecast production levels have been achieved in FY2021. Mining Equipment Stillwater Mine Operations at Stillwater Mine are mechanised, employing various pieces of equipment which is listed in Table 39. For both the Stillwater West and East Sections, the mine makes use of 4.0 cubic yard and 6.0 cubic yard LHDs for infrastructure development and 2.0 cubic yard LHDs for operations on the reef including reef development and stope ore removal. Other key elements of the current fleet are face drill rigs, bolters and dump trucks. These are further supported by numerous utility and transport units. The Qualified Person is satisfied that, accounting for the geographical separation of the stoping and development areas and the daily production called for, the Stillwater East Section has sufficient equipment to meet current production targets. The Stillwater East Section is currently under development and the mining equipment included in Table 39 is currently being employed for development and ore production. The planned development and production build-up and the resulting mechanised equipment requirements are supported by a detailed capital expenditure and equipment procurement schedule, providing for mining equipment procurement of approximately US$156 million over the FY2022 to FY2026 period. The Qualified Person is of the opinion that sufficient equipment has been scheduled for procurement over the next five years to meet the expanding production levels planned for the Stillwater East Section. Table 39: Stillwater West Section Current Mechanised Mining Equipment Quantities Equipment Description Number of Existing Units Mechanised Bolters 11 CMAC Bolters 36 Face Drill Rigs 33 LHDs 75 Dump Trucks 24 Utility Vehicles 221 Tractors 6 Locomotives 13 Total 419 A combination of vertical hoisting (via the shaft) and tramming (via trains and locomotives) is employed for the transport of ore and waste from the underground workings to the processing facility on surface. Currently, 60% of ore generated underground at the Stillwater Mine is hoisted via the shaft with the remainder being transported via train. The quantity of ore transported by rail will increase as the production levels at the Stillwater East Section increase.


147 East Boulder Mine Operations at East Boulder Mine are also mechanised, employing the equipment as listed in Table 40. The mine makes use of 4.0 cubic yard and 6.0 cubic yard LHDs for infrastructure development and 2.0 cubic yard LHDs for production mining operations on the reef, including development and stope ore removal. Table 40: East Boulder Mine Mechanised Mining Equipment Quantities Equipment Description Number of Existing Units Mechanised Bolter 5 CMAC Bolter 8 Face Drill Rigs 16 LHDs 34 Dump Trucks 7 Utility Supply Flatbeds 13 Tractor 13 Forklifts 8 Skidsteer 5 Locomotives 9 Mine Transportation 62 Road Maintenance 4 Total 176 The Qualified Person is of the opinion that, accounting for the geographical separation of the stoping and development areas and the daily production called for in the LoM production plan, the mine currently has sufficient equipment to meet production targets. Logistics Stillwater Mine A total of eleven adits have been driven and access underground workings at the Stillwater Mine; six are main accesses and intakes, four are dedicated exhausts, and one is an auxiliary drift. The main rail haulage adits are the 5000W and 5000E Levels. Ore is dropped down from the upper levels via a series of ore and waste passes to transfer boxes on 5000W Level from where the rock is railed to the mine portal by diesel locomotives. The rail cars discharge ore or waste into a purpose-built tip that dumps into a haul truck. The haul truck dumps the ore onto a RoM stockpile ahead of the concentrator. The waste rock is transported to the East Side Waste Rock Dump. For the Stillwater East Mine, ore and waste is dropped down from the upper levels via a series of AlimakTM ore and waste passes to transfer boxes on the 5000E Level from where the rock is railed to the mine portal by diesel locomotives. The rail cars discharge ore or waste into two dumps that drop the material into a “box” from where surface loaders pick up the material and load haul trucks that transport and dump the ore onto a RoM stockpile ahead of the concentrator or haul the waste to the East Side Waste Rock Dump. Ore and waste rock from the levels below the portal adit of the 5000 Level is hoisted to surface via the Vertical Shaft. Ore and waste rock is transferred from all the levels above 3500W and below 5000 Level via a series of raise-bored ore and waste rock passes to the main transfer boxes on the 3500W Rail Level. 148 Rock material (ore or waste) is hauled by tandem 20-ton diesel locomotives with on average twelve ore cars per train and discharged into the mine tip on 3500 Level which reports to the shaft. All broken rock from the rock passes reports to the main jaw crusher which in turn feeds, via an apron feeder, onto the main conveyor belt on 3100W Level. The conveyor belt feeds into the main surge box prior to loading into measuring flasks at the skip boxes. The ore and waste rock is hoisted separately to surface using two 10-ton skips and deposited on separate stockpiles. There is sufficient available hoisting time to meet the LoM production requirements. A double deck 50-person capacity service cage is also available in the shaft that can move men and material from surface to service all levels between 4400 Level and 3100 Level. A fully equipped ramp has been developed down to the 1600 Level, which is currently the lowest level on the mine. The ramp is used to haul production from the 2900, 2600, and 2300 Levels by bringing rock to the loading level of the shaft on 3500 Level. All ore and waste rock generated between 1600 Level and 2900 Level gravitates via rock passes down to lower levels where it is loaded via hydraulic chutes into articulated 30-ton haul trucks. Thereafter, the rock material is hauled to 2600 Level and discharged into the appropriate tips, which feed the 2500 Level chutes. The ore and waste rock is then loaded from the 2500 Level ore and waste chutes and hauled up the ramp to the 3500 Level by 42-ton diesel powered haul trucks. The various adits and the Vertical Shaft are used for the supply of all services to the underground operations, including compressed air, water supply, power, sandfill, and the transport of men, materials, equipment, diesel, explosives and rock. The Qualified Person is of the view that logistics employed at the Stillwater West Section for the transport of men, material and rock have sufficient capacity to meet the planned production levels. Considering the current and future design logistics capacities for the Stillwater East Section, there will be sufficient logistical support to meet the planned increases in production in this section. East Boulder Mine East Boulder Mine is accessed by two parallel tunnels from the surface portal, with the 6500 Level main access level equipped with 90lb rail for the transport of personnel, materials and rock to and from the mine. All levels above and below this access level are operated as trackless mining sections. Broken rock material (ore and waste) from the upper levels above the 9100 Level is transported to internal tips within each of the independent ramp systems. Ore and waste rock from the upper levels is gravitated to the main 6500 Level rail haulage via drop raises and Alimaks to near vertical ore and waste rock passes to transfer boxes on the 6500 Level from where the rock is railed to the surface by diesel locomotives. There are some internal transfers on the 7500, 7900 and 8500 Levels to place ore and waste into the Life of Mine (LoM) pass systems. All rock material on the upper levels passes through a grizzly to prevent blockage of the rock passes. Once on surface, the rail cars discharge the ore or waste material 149 into dedicated tips from where ore is conveyed to the concentrator stockpile and waste is loaded out for tailings dam wall construction. The twin 6500 Level access tunnels (Tunnel 1 and 2) are used for the supply of all services underground, water, power, sandfill, and the transport of personnel, materials, equipment, diesel, explosives and rock. Compressed air is supplied by underground compressors near the main shop complex and all compressed air passes through a dryer to remove excess water from the air stream. During FY2019 and FY2020, Tunnel 2 was subjected to a rail upgrade to improve train cycle times required to meet the increasing levels of production (ore and waste) associated with the Fill the Mill Project. This work was completed after an 18-months period in June 2020. The Qualified Person is of the opinion that, with the completion of the Tunnel 2 rail upgrade, the logistics employed at East Boulder Mine for the transport of personnel, material and rock are adequate to meet the planned production levels. Underground Mine Services Stillwater Mine 13.11.1.1 Overview Stillwater Mine continues to develop its infrastructure in FY2024 and beyond to accommodate the increased mining footprint resulting from the Stillwater East Section expansion. The infrastructure in place has been expanded to allow the mine to execute its LoM plan. 13.11.1.2 Ventilation Access and service adits and shafts are utilised for the ventilation of underground operations. In the Stillwater West Section (Figure 58), the openings are split between:  Intakes: Stillwater Shaft,50W Portal (x2), 50E Portal (x2), 5500W Portal, Benbow Portal, and 5900 Portal;  Exhaust openings: 5400E Portal, 5400E Raisebore breakouts (x2), 5150W Portal, 5300W Portal, 6600W Alimak to Surface breakout, and the 6600W breakout adit, 5300W West Fork Alimak to Surface Breakout, 56E13800 Alimak to surface breakout (x2). 150 Figure 58: Graphic of Ventsim Model for the Stillwater West Section In the Stillwater East Section, there are two main intakes (5000E Rail Portal and 5000E Portal) and two 56E13800 Alimaks to Surface Breakouts for exhaust as well as the E21900 Alimak needed in FY2031as shown in Figure 59. Figure 59: Graphic of Ventsim Model for the Stillwater East Section Ventilation temperature is planned to be conducive to optimum machine and personnel productivity and this will be achieved by using propane bulk air heaters installed at the main intake airways to be operated in winter to limit water freezing. The maximum temperature for operations underground is targeted to be less than 85°F wet bulb. Stillwater Mine draws approximately 2 100 000 cubic feet per minute (cfm) of ventilation air through the exhaust system via sixteen main exhaust fans, ranging from 400hp to 850hp, situated at various ventilation raises and adits. Ventilation flow is supplemented by booster fans ranging from 30hp to 150hp to create a mine-wide negative pressure system. Stope ventilation is achieved with 30hp to 100hp axial


151 fans in conjunction with rigid and lay-flat ducting. Total primary fan power installed in the system is 8 450hp. Stillwater Mine has implemented two main ventilation system upgrades scheduled to be completed in 2024:  Stillwater East Section: The four 400HP primary fans at the 56E13800 Alimak Raises to surface were upgraded to four 700HP mixed flow primary fans. The increase in horsepower was to support future production and with the mixed flow fans, the main exhaust flow can be adjusted dynamically. Portal heaters are being installed at the Benbow Portal to allow for it to be used as an intake and provide ventilation to the eastern portion of the Stillwater East Section;  Stillwater West: Two 850HP primary mixed flow fans were installed at the bottom of the 5300W West Fork Alimak to Surface Breakout (WFVR) in FY2023. In FY2024, two additional 850HP units will be installed for a total of four primary fans at this location. In FY2024, the 5150W and 5300W Portals will be swapped to intake airways as the ventilation system is converted to use the WFVR as the main exhaust; and  Overall strategy of the WFVR is to have the exhaust raises on the far western extent of mining with the main power at the exhaust fans, reducing the requirements for booster fans. The ventilation plan over time will convert more levels to exhausting through the WFVR and will result in the decommissioning of primary vent fans on the 4800W and 6600W Levels. The 850HP fans are mixed flow units and the main exhaust flow can be adjusted dynamically. Air entering the mine on the 5000W, 5000E, Benbow Decline, 5500W, and 5900W portals and the shaft is heated via propane bulk air heaters in the winter to prevent freezing of pipes and to ensure productive working temperatures. 13.11.1.3 Mine Dewatering The lowest level at Stillwater Mine is the 1400W Level Decline and the lowest operational level is the 1600 W Level. Stillwater Mine has installed a series of “leapfrog” interim dams and pumps for the removal of waste and fissure water from these low points. Water is pumped from one pump station/sump up to the next in consecutive lifts to bring the water out of the mine via the 1900W Level Pump Station. Drain water is collected in sumps in the various haulages and pumped to the main pumps station or a drain hole on that level to ensure haulages and declines are kept dry. The 1900W Level Pump Station comprises six main pumps which pump water to an intermediate pump station on the 2500W Level, which pumps to a series of sumps on the 3100W Level, and water is then pumped from this intermediate pump station to the 4400W Level Pump Station. This water is then pumped up to the 5300W Level Surge Reservoir from where it is gravity fed to the West Clarifier on surface. Water from areas above the 5000E Level at the Stillwater East Section reports to the East Clarifier on surface while the remainder of the water reports to the West Clarifier through the 5300W level surge reservoir. A disk filtration system installed on surface in FY2020 was commissioned in Q1 FY2021 which was designed to treat all water disposed of via percolation and the Land Application and Disposal facility adjacent to the Hertzler Tailings Storage Facility to comply with recently issued water disposal regulations. 152 The current pumping capacity at Stillwater Mine is approximately 2 500gal per minute and is adequate for handling the expected amount of mine inflow water. In addition, clarifier upgrades were completed in FY2021 to increase capacity to 2 500gal per minute for each of the two clarifiers resulting in a total clarifier capacity of 5 000gal per minute. The Qualified Person is of the opinion that Stillwater Mine has an appropriate mine dewatering system, and that the dewatering system can handle all water inflows into the mine. 13.11.1.4 Compressed Air The installed compressed air system at Stillwater Mine consists of eleven stationary compressors for 19 600cfm of capacity. There are six compressors on the east side and five on the west side. These compressors are all located on surface and are tied into the total mine system by underground piping and a 12-inch diameter on-surface trunk line between the east side compressor house and the west side Loci Barn compressor house. Compressed air volumes are being increased as production ramps up in the Stillwater East Section. In FY2021, an engineering study was launched with the inhouse projects team and executed by Nordmin Engineering to further delineate future needs. The compressed air service map for Stillwater Mine is shown in Figure 60. Figure 60: Stillwater Mine Compressed Air Service Map 153 13.11.1.5 Service Water The present service water system provides the Stillwater East Section with approximately 550gal per minute of service water, which is sufficient for the projected production from this section. The 550gal per minute was calculated by taking historical Stillwater Mine service water quantities and correlating with the total tons of rock broken during the same period. This calculation took into consideration all sandfill, diamond drilling, mining and miscellaneous water uses required for the production at Stillwater Mine. The present surface pump house delivers service water to the Stillwater East Section and, as the production in this section continues to ramp up, the service water demand will increase. To meet the increased demand, the service water piping was upgraded to 8-inch diameter Schedule 40 steel pipe. The 8-inch steel pipe was installed from the 5000E Portal through the 5000E Drive (TBM tunnel) to the bottom of the 5600E15-200 Utilities boreholes in Q1 FY2021. An upgrade of the three vertical turbine pumps motors to 100hp in the surface pump house was required to meet the ultimate steady-state water demand. These upgrades, along with the 8-inch piping upgrade, allow the surface pumps to deliver 550gal per minute of water to the 5600E15-200 Drill Water Reservoir (DWR), which was commissioned in May 2020. The 4700W service water system that feeds the FWL was commissioned in FY2022 and the 6000E reservoir was commissioned in FY2023. A schematic diagram showing the Stillwater East Section service water reticulation is shown in Figure 61. Figure 61: Stillwater East Section Service Water Reticulation 154 East Boulder Mine 13.11.2.1 Overview East Boulder Mine continues to increase its mining footprint and development continues upwards to generate more Mineral Reserves. This development is supported by the necessary mine services and infrastructure, which includes the following:  6500, 7200 and 8200 Level sand plants;  An additional sand plant on the 8800 Level is planned for commissioning in FY2025;  A fully optimised ventilation system is planned for completion in FY2024;  Infrastructure for the 72740-ramp system; and  Infrastructure required for the development of the 7500 and 7200 Footwall Levels and the Frog Pond incline. 13.11.2.2 Ventilation At East Boulder Mine, ventilation openings are split between the following:  Intake ways: 6500W Portals (x2) and BVR Alimak Intake Raise (Figure 62); and  Exhaust ways: Simpson Creek Raise, BVR Alimak Exhaust Raise, Graham Creek Raise, 79W FWL (surface breakout in FY2027) and 75E Alimak to surface in FY2029. East Boulder Mine draws 550 000cfm of air to ventilate the underground operations via four main mains fans, 400hp exhaust fans located at the Brownlee Ventilation Raises (two) and Simpson Creek Raise and one 600hp fan located at the Graham Creek Raise. The air is exhausted via two vertical raises to the Frog Pond adit, a raise to Simpsons Creek adit and the Graham Creek Raise. Additional forcing fans are utilised in primary development sections. Stope ventilation is achieved with 40hp to 100hp axial fans in conjunction with rigid and lay-flat ducting. Whenever possible, through ventilation is achieved by establishing a raise from the sill level of the stope to the level above. This allows separate and unique air from the primary circuit to flow through the stopes. Figure 62: Graphic of Ventsim Model for the East Boulder Mine East Boulder Mine has implemented a main ventilations system upgrade which is scheduled to be completed in FY2024 and this upgrade entails the following:


155  An 850HP mixed flow fan has been installed at the Graham Creek Raise to provide the primary exhaust for the Western extent of the East Boulder. The main exhaust flow can be adjusted dynamically;  The Frog Pond Alimak Raises (BVR) have had a major upgrade with a passive heat exchanger installed on surface at the top of the raises. One raise has been commissioned as an intake airway which allows for intake air to be delivered to the 7500W FWL;  The two existing 400HP fans will be replaced by a singular 600HP mixed flow fan installed at the bottom of the exhaust raise. The main exhaust flow can be adjusted dynamically; and  Overall strategy is to get another intake in at East Boulder Mine to increase air quality and reduce main fan pressure. The system is split into two vent zones with it generally described as the 6500 Portals feeding the western side of the mine and exhausting through the Graham Creek Raise and the BVR intake raise feeding the eastern side and being exhausted through the Simpon Creek and BVR exhaust raise. Air entering the mine on the 6500 Level is heated via two propane bulk air heaters in the winter to prevent freezing of pipes and to ensure productive working temperatures. Air entering the mine through the BVR intake raise is passively heated using mine air from the BVR exhaust raise at the top of the BVR raises. Air temperature is monitored and air flow is regulated through the BVR intake to keep intake temperatures above freezing in the wintertime. The Qualified Person is satisfied with the current ventilation system which provides air flow that is adequate for the mine’s needs. 13.11.2.3 Mine Dewatering Mining operations are primarily situated above the main adit level allowing for water drainage from the active sites and, therefore, water pumping is not a major challenge. Furthermore, water inflow from fissures and underground aquifers is minimal. Ramp development below the 6500 Level is equipped with normal mobile pumps and cascade sump/pumps to bring the water to the 6500 Level. Water management focus is primarily to ensure that there is adequate infrastructure to manage service water and wastewater from the underground fill. The pumping capacity of the mine is approximately 396gal per minute from the main pump station on the 6500 Level, which exceeds the historical and current water flow rates of less than 250gal per minute. The Qualified Person is satisfied with the pumping capacity at the mine, which meets the current and future needs of the mine. 13.11.2.4 Compressed Air The present compressed air system at East Boulder Mine consists of five stationary compressors and a mine wide distribution system. These compressors are all located underground and are tied into the mine compressed air system by underground piping and a controller, and deliver compressed air based on demand. Air is piped via an 8-inch diameter main trunk on the 6500 Level, 6-inch diameter pipes up each ramp, and 6-inch or 8-inch lines on each level. There is also a dedicated 10-inch trunk that runs from the compressors near the central shop to the 7500 Level. All the pipes are interconnected. Each compressor is rated at 500hp and can deliver 1 750cfm at 125psig at the 6500 Level elevation. Collectively, all compressors can deliver over 8 700cfm but only four compressors are required to run at 156 peak demand, with normal duty requiring three compressors run online and with the fifth providing the required redundancy. A compressed air dryer was commissioned on 6500 Level in early FY2020 to reduce water in the air lines. A 10-inch diameter pipeline loop from the 7500 Level up to the 8200 Level was installed in FY2020 to increase storage capacity above the 7500 Level. A 200 HP satellite compressor was added in FY2021 to service a long hole drilling machine, with three more satellite compressors to be added and installed at long hole drilling locations. In addition, studies on long-term engineering and option planning started in FY2021 and scheduled for completion in FY2022 will which more closely define the long-term compressed air requirements and strategy. As a result, the Qualified Person is satisfied with the compressed air system in place at East Boulder Mine. The compressed air service map for East Boulder Mine is shown in Figure 63. Figure 63: East Boulder Mine Compressed Air Distribution System 13.11.2.5 Service Water The current service water system consists of multiple DWRs situated on each level underground (Figure 64). The DWR system is fed from the riser pump located at the surface clarifier, which receives the return water from the mining activities underground. The clarified water is pumped underground via 157 a pipeline from the clarifier to the 6500 Level DWR from where it is pumped vertically to the DWRs at the higher levels in the mine in a cascading fashion – DWRs are located at the 6500, 6700, 6900, 7200, 7500, 7900, 8200, 8500 and 8800 Levels. Clean Portal Water is also distributed to the 6500 DWR via a pipeline in Tunnel 1 from a sump inside Portal 1. The future water distribution plan provides for one more DWR at the 9100 Level. The DWRs are equipped with pump skids that have two pumps per skid, each pump delivering 300gal per minute at 350ft of head. The 7900, 8200, 8500 and 8800 DWRs are controlled via variable frequency drives (VFDs) and 40hp pumps, whereas the rest of the DWRs have 125hp direct feed pumps. Each system is sufficient and the DWR planned will be constructed with 40hp pumps and VFDs. The Qualified Person is satisfied with the current service water system, which provides sufficient service water to the mining operations, and no major additions are required. The planned upgrades will ensure the mine has sufficient service water for to the expanded operations. Figure 64: East Boulder Mine Drill Water Reservoir Layout Manpower Table 41 and Table 42 show the LoM manpower plans for Stillwater and East Boulder Mines, respectively. The revision of the LoM plan for Stillwater Mine has resulted in a progressive reduction in the headcount for the mining, technical services and administration, concentrator, surface operations and engineering and maintenance complements, from a total headcount of 1 236 in FY2021 to 1 102 in FY2023. The reduction trend is planned to continue across all disciplines except for concentrator and surface 158 operations resulting in a total headcount of 995 in FY2024 followed by a progressive increase from FY2025 (total headcount of 1 126) to FY2031 (total headcount of 1 288) in line with the planned production ramp up. As per the current LoM plan, total headcount is planned to remain stable at the FY2031 level for the remainder of the LoM to sustain the planned steady state production levels. Total headcount for East Boulder Mine has been stable over the period FY2021 to FY2023 (457-461) but this is planned to increase by 9% during FY2024 and FY2025 to 503. Total headcount will remain stable at 501 from FY2026 onwards until FY2046 and thereafter decrease progressively until the end of the LoM. Table 41: LoM Manpower Plan for Stillwater Mine FY2021 FY2022 FY2023 FY2024 FY2025 FY2026 FY2027 FY2028 FY2029 FY2030 FY2031 FY2032 Mining 870 790 708 597 598 666 686 725 753 757 789 773 Engineering Maintenance 148 140 205 199 199 227 230 240 250 250 250 250 Technical Services & Admin 147 141 140 96 97 115 115 117 117 117 117 117 Concentrator 43 43 33 42 42 58 58 61 66 71 71 71 Surface 28 22 16 61 62 60 59 60 62 62 62 62 Total Mine Site 1 236 1 136 1 102 995 998 1 125 1 147 1 202 1 247 1 256 1 288 1 271 FY2033 FY2034 FY2035 FY2036 FY2037 FY2038 FY2039 FY2040 FY2041 FY2042 FY2043 FY2044 Mining 767 768 764 762 765 758 750 750 740 733 728 688 Engineering Maintenance 250 250 250 250 250 250 250 250 250 250 250 250 Technical Services & Admin 117 117 117 117 117 117 117 117 117 117 117 117 Concentrator 71 71 71 71 71 71 71 71 71 71 71 71 Surface 62 62 62 62 62 62 62 62 62 62 62 62 Total Mine Site 1 266 1 267 1 263 1 261 1 263 1 257 1 249 1 249 1 239 1 232 1 227 1 187 FY2045 FY2046 FY2047 FY2048 FY2049 FY2050 FY2051 FY2052 FY2053 FY2054 Mining 678 666 645 654 551 533 544 507 465 295 Engineering Maintenance 250 250 250 250 238 238 238 214 194 141 Technical Services & Admin 117 117 117 117 117 117 115 115 104 104 Concentrator 71 71 71 71 71 71 71 46 46 46 Surface 62 58 58 58 58 58 58 46 46 46 Total Mine Site 1 177 1 161 1 140 1 149 1 034 1 016 1 025 927 855 632 Actual Description Budget Description Description Budget Budget


159 Table 42: LoM Manpower Plan for East Boulder Mine The Qualified Persons noted that lower mining productivities when viewed in terms of tonnage generated per number of mining employees are forecast at East Boulder Mine from FY2024 until FY2040 (average 1 362 tons per employee) than achieved since FY2021 (1 440 tons per employee) after which productivity is forecast to increase to the FY2021-2023 level. Using this metric, productivity levels at Stillwater Mine declined from 727 tons per employee in FY2021 to 661 tons per employee in FY2023. A reversal of this downward trend is anticipated in FY2024 followed by a progressive improvement to approximately 955 tons per employee in FY2030 from where it is kept at the level of 932-1323 tons per employee for the remainder of the LoM. The Qualified Persons are satisfied with the current manpower plans for Stillwater and East Boulder Mines which are aligned to the actual levels of productivity achieved previously. FY2021 FY2022 FY2023 FY2024 FY2025 FY2026 FY2027 FY2028 FY2029 FY2030 FY2031 FY2032 FY2033 FY2034 FY2035 FY2036 FY2037 Mining 294 293 311 308 318 315 315 315 315 315 315 315 315 315 315 315 315 Engineering Maintenance 71 74 64 91 91 91 91 91 91 91 91 91 91 91 91 91 91 Technical Services & Admin 46 51 47 50 50 51 51 51 51 51 51 51 51 51 51 51 51 Concentrator 30 27 28 33 33 33 33 33 33 33 33 33 33 33 33 33 33 Surface 16 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 Total Mine Site 457 456 461 493 503 501 501 501 501 501 501 501 501 501 501 501 501 FY2038 FY2039 FY2040 FY2041 FY2042 FY2043 FY2044 FY2045 FY2046 FY2047 FY2048 FY2049 FY2050 FY2051 FY2052 FY2053 FY2054 Mining 315 315 315 315 315 315 315 315 315 307 307 307 307 306 306 306 299 Engineering Maintenance 91 91 91 91 91 91 91 91 91 91 91 91 91 91 91 91 92 Technical Services & Admin 51 51 51 51 51 51 51 51 51 51 51 51 51 51 51 51 51 Concentrator 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 Surface 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 Total Mine Site 501 501 501 501 501 501 501 501 501 493 493 493 493 492 492 492 486 FY2055 FY2056 FY2057 FY2058 FY2059 FY2060 FY2061 FY2062 FY2063 FY2064 FY2065 FY2066 FY2067 FY2068 FY2069 Mining 299 291 291 291 291 236 236 221 216 204 204 204 160 108 60 Engineering Maintenance 92 92 92 92 92 78 78 78 78 78 78 78 56 56 56 Technical Services & Admin 51 51 51 51 51 47 47 47 47 47 47 47 29 29 29 Concentrator 33 33 33 33 33 33 33 33 33 33 33 16 9 9 9 Surface 11 11 11 11 11 11 11 11 11 11 11 11 8 8 8 Total Mine Site 486 478 478 478 478 405 405 390 385 373 373 356 262 210 162 Description Description Budget Budget Budget Description Actual 160 PROCESSING AND RECOVERY Mineral Processing Methods Background Ore processing plants at Stillwater and East Boulder Mines and the smelter and base metal refinery at the Columbus Metallurgical Complex have been in continuous operation for decades. All metallurgical processes and technology in place at the ore processing, smelting and refining facilities are appropriate, well-proven and aligned to norms and practices in the PGM sectors. The processing methods were selected based on metallurgical testwork carried out as part of feasibility studies at the time of development. However, results of the testwork have been superseded by actual operational data and experience accumulated over several years of continuous successful operation of these facilities. Accordingly, there are no plans to introduce new processing technology at the processing facilities. The recently completed plant capacity upgrades at Stillwater Concentrator and the metallurgical complex were based on existing technology and process flowsheets. There are no expansion plans anticipated at the East Boulder Concentrator which has historically been operated below nameplate capacity. Higher utilisation of the installed capacity at the East Boulder Concentrator continues based on existing and proven technology and process flowsheet. Ore Processing Stillwater Concentrator 14.2.1.1 Plant Design and Equipment Specifications The Stillwater Concentrator was commissioned in 1986 and since been upgraded to 3 400-ton per operating day conventional crushing, milling, flotation, and filtration plant producing a PGM-base metal sulphide concentrate suitable for downstream smelting and refining. Primary crushing equipment consists of Metso (Nordberg) feeder and jaw crusher with a capacity of 300 tons per operating hour. Primary grinding equipment consists of:  A Metso 3 000HP semi-autogenous grinding (SAG) mill charged with 4-inch hardened steel balls and with a capacity of 179 tons per operating hour; and  A Metso 3 000HP ball mill charged with 3-inch hardened steel balls and with a capacity of 179 tons per operating hour. The flotation circuit consists of:  Flash flotation circuit containing a Metso flash cell and Metso cleaner cells;  Rougher flotation circuit consisting of twelve Metso 300cft convention flotation cells;  Rougher-cleaner flotation circuit consisting of two 3ft Metso column flotation cells, two 1.5ft Metso column flotation cells, and three Metso 350cft conventional cleaner flotation cells;  Middling flotation circuit consisting of six Metso 300cft conventional flotation cells;  Middling cleaner flotation circuit consisting of eight Metso 300cft conventional cleaner flotation cells;  Scavenger flotation circuit consisting of ten Metso 300cft conventional flotation cells; and 161  Scavenger cleaner flotation circuit consisting of eight Metso 300cft conventional cleaner flotation cells and a 5ft column flotation cell; Filtration equipment consists of a Metso 10 plate pressure filter with a capacity of 100 tons concentrate per day (4 300 tons per day ore feed). 14.2.1.2 Plant Capacity The PGM concentrator at Stillwater Mine was commissioned in 1986 as a 500-ton per operating day conventional crushing, milling and flotation plant. Following several process modifications and expansions, the concentrator capacity increased to approximately 3 100 tons per operating day by FY2020. The concentrator has historically operated on a ten-day or eleven-day fortnight basis and has been switched off every second weekend resulting in approximately 75% utilisation. This was required to maintain the balance with mining volumes of 750 000 tons per year at the time, but the concentrator currently operates on a continuous basis with a target utilisation of 92% due to the increased tonnage delivered from the mine in recent years. At the 92% utilisation, the plant capacity before expansion is equivalent to approximately 1.04 million tons per year. A significant capital expansion project at the Stillwater Concentrator was finalised and commissioned in late (Q3) FY2023. This expansion has resulted in an operational capacity increasing to 3 400 tons per operating day (i.e., 1.1 million tons per year) at full utilisation. This capacity will accommodate additional ore from the Stillwater East Section until FY2028 and additional capacity is required for the steady state steady production targets exceeding 1.1 million tons per annum. A bottleneck in the flotation circuits needs to be resolved to upgrade capacity further to 4100 tons per day (i.e. approximately 1.4 million tons per annum at 92% utilisation) as per the Blitz Project plans. Mechanical equipment needed for the flotation circuit upgrades has already been procured as part of the Blitz Project Sibanye-Stillwater has undertaken to complete this work at an additional cost of approximately $1.8 million (labour cost) a year before the capacity of 1.4 million tons is required. The following areas of the concentrator have already been upgraded to increase tonnage throughput capacity as part of the Blitz Project:  Milling Section: A new SAG mill, a new ball mill and new pebble crushing facility were installed to replace an existing comminution facility which was decommissioned. The new milling building was commissioned in late (Q3) FY2023 and there is no additional project capital provision for this section beyond FY2023;  Flotation Section: Associated with the milling circuit replacement, the flash flotation cells were also be replaced with new cells. The remainder of the flotation circuit required minimal expansion, with the addition of a few cleaner cells, and the increase in capacity of some of the float column cells. The old float plant building had sufficient capacity and infrastructure to accommodate the minor expansions required. This upgraded circuit was commissioned in parallel with the new milling circuit in Q3 FY2023. Further upgrades to the remaining flotations circuits required to increase plant capacity from 3 400 tons to 4 110 ton per day (i.e. 1.1 million tons to 1.4 million tons per year at 92% utilisation) have been considered but deferred to a time when the additional capacity is needed (i.e. from FY2029 onwards);  Tailings Section: Upgrades were completed in FY2023 on the tailings distribution system between the mill and final tailings discharge pump to the TSF. These also included upgrades to slurry pumps, 162 distribution lines, and system controls to handle the increased throughput. Minor upgrades are planned to be completed in FY2024 to the tailings lines going to the TSF to improve system reliability at the maximum planned throughput; and  Concentrate Handling: Upgrade of the concentrate handling facility was commissioned at the end of FY2020. The concentrate thickener has been replaced and a new stock tank and filter press have been installed. The dry concentrate bin has also been replaced to allow delivery into the new side-tipping trucks, which have been implemented for the transportation of the concentrate from the mine to the Columbus Metallurgical Complex. These same trucks return with slag and reverts for reprocessing. 14.2.1.3 Manpower Requirements The plant staffing comprises four crews operating on two 12-hour shifts of one Supervisor, four Operators and a Tailings Storage Facility Operator. Current budget staff is twelve Maintenance (Mechanical) Technicians to support Concentrator, Surface Operations, Paste Plant, Water Treatment, and Building Maintenance and these technicians follow the 24-hour per 7-day week shift rotation system. There are four Electrical Technicians with the same area of responsibility as Concentrator Maintenance Technicians but working on a seven-day per week basis. Major and routine planned maintenance is scheduled on a regular basis to ensure the plant mechanical availability of 92% is maintained. 14.2.1.4 Process Description The concentrator currently receives ore from the Off-shaft and Upper West areas of the Stillwater West Section and Blitz West area of the Stillwater East Section as well as slag and brick recycle materials from the smelter. Smelter slag and brick recycle materials are delivered to the primary crushing area and are campaign-treated through the concentrator. A typical slag campaign would last 24 hours and would entail process changes such as different reagent dosages, lower throughput and shutting down the flash float circuit. Approximately 75% to 80% recovery of contained 2E is the sustainable target for these campaigns. The concentrator has previously processed approximately 1.1 million tons per year of RoM ore feed at a 92% total 2E recovery from this material (FY2020). The concentrator capacity expansion was based on the existing process flow diagram which is presented in Figure 65. The process comprises open circuit crushing followed by two stages of milling, with the sized product being delivered to the flotation circuit. Various stages of flotation including roughing, cleaning and scavenging in addition to a regrind circuit ensure that recovery is optimised and concentrate grades suitable for smelting are realised.


163 Figure 65: Block Flow Diagram of the Stillwater Concentrator 14.2.1.5 Production Plan The recent history and budget operational parameters for the concentrator are presented together with the LoM production plan in Table 43, Figure 66 and Figure 67. The FY2021, FY2022 and FY2023 data presented reflects the actual annual performance whilst the FY2024 to FY2054 data represents current budget targets. The current operational methods and capacities are adequate until FY2028 after which flotation circuit upgrades will be required to increase overall concentrator capacity to 1.4 million tons per annum. The metallurgical efficiencies projected have not been obtained historically, but as a result of the process upgrades completed in FY2023 and the minor increases projected, these are deemed reasonable budget targets. However, the flotation circuit debottlenecking project should be completed to increase concentrator capacity to 1.1 million tons before FY2029. Table 43: Stillwater Concentrator Actual and Forecast LoM Operational Throughput and Outputs FY2021 FY2022 FY2023 FY2024 FY2025 FY2026 FY2027 FY2028 FY2029 FY2030 FY2031 FY2032 Total Feed tons 936 439 779 288 792 082 782 359 777 832 930 205 982 715 1 109 772 1 179 270 1 200 093 1 199 806 1 200 489 Concentrate Produced tons 22 703 19 415 21 293 21 132 21 000 25 112 26 483 29 932 31 867 32 394 32 543 32 624 2E Recovery % 91.62 91.70 91.20 91.80 91.80 91.79 91.63 91.70 91.88 91.77 92.22 92.40 2E Metal Produced oz 346 556 260 206 262 923 276 549 278 684 344 027 397 921 454 202 489 309 499 275 515 085 509 492 FY2033 FY2034 FY2035 FY2036 FY2037 FY2038 FY2039 FY2040 FY2041 FY2042 FY2043 FY2044 Total Feed tons 1 199 978 1 199 360 1 200 991 1 200 231 1 198 986 1 200 637 1 199 549 1 198 752 1 200 051 1 199 820 1 200 820 1 199 872 Concentrate Produced tons 32 570 32 517 32 568 32 621 32 569 32 546 32 480 32 465 32 468 32 451 32 521 32 557 2E Recovery % 92.28 92.18 92.20 92.41 92.36 92.16 92.06 92.08 91.99 91.96 92.08 92.25 2E Metal Produced oz 502 245 495 265 499 585 497 625 494 227 488 557 492 074 494 497 475 578 473 200 491 188 496 765 FY2045 FY2046 FY2047 FY2048 FY2049 FY2050 FY2051 FY2052 FY2053 FY2054 Total Feed tons 1 203 718 1 199 573 1 201 232 1 199 847 1 199 641 1 199 983 1 200 282 1 199 816 1 131 245 475 596 Concentrate Produced tons 32 677 32 469 32 515 32 516 32 525 32 521 32 555 32 521 30 802 12 950 2E Recovery % 92.30 92.03 92.03 92.14 92.18 92.15 92.22 92.16 92.58 92.58 2E Metal Produced oz 490 641 478 375 482 421 478 053 491 071 485 967 531 009 508 824 541 383 231 682 Parameter Unit Unit Unit Actual Parameter Parameter Budget Budget Budget 164 Figure 66: Stillwater Concentrator Actual and Forecast LoM Operational Throughput and Outputs Figure 67: Stillwater Concentrator Actual and Forecast LoM Operational Data 14.2.1.6 Energy Requirements The energy requirement for the Stillwater Concentrator is 6.5MW and is fed by a feed rated for 15MW and a 21.8MW substation. Power to the concentrator is fed from the West Substation as detailed in Section 15.1.4 and is delivered to the plant via incoming Line #2. The substation has sufficient capacity for the concentrator and the planned expansions. - 5 10 15 20 25 30 35 40 0 200 400 600 800 1 000 1 200 1 400 1 600 FY 2 0 2 1 FY 2 0 2 2 FY 2 0 2 3 FY 2 0 2 4 FY 2 0 2 5 FY 2 0 2 6 FY 2 0 2 7 FY 2 0 2 8 FY 2 0 2 9 FY 2 0 3 0 FY 2 0 3 1 FY 2 0 3 2 FY 2 0 3 3 FY 2 0 3 4 FY 2 0 3 5 FY 2 0 3 6 FY 2 0 3 7 FY 2 0 3 8 FY 2 0 3 9 FY 2 0 4 0 FY 2 0 4 1 FY 2 0 4 2 FY 2 0 4 3 FY 2 0 4 4 FY 2 0 4 5 FY 2 0 4 6 FY 2 0 4 7 FY 2 0 4 8 FY 2 0 4 9 FY 2 0 5 0 FY 2 0 5 1 FY 2 0 5 2 FY 2 0 5 3 FY 2 0 5 4 FY 2 0 5 5 C o n c e n tr a te ( th o u sa n d t o n s) Fe e d ( th o u sa n d t o n s) RoM Ore Feed Recycle Feed Concentrator Capacity Concentrate Produced 0 100 200 300 400 500 600 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 FY 2 0 2 1 FY 2 0 2 2 FY 2 0 2 3 FY 2 0 2 4 FY 2 0 2 5 FY 2 0 2 6 FY 2 0 2 7 FY 2 0 2 8 FY 2 0 2 9 FY 2 0 3 0 FY 2 0 3 1 FY 2 0 3 2 FY 2 0 3 3 FY 2 0 3 4 FY 2 0 3 5 FY 2 0 3 6 FY 2 0 3 7 FY 2 0 3 8 FY 2 0 3 9 FY 2 0 4 0 FY 2 0 4 1 FY 2 0 4 2 FY 2 0 4 3 FY 2 0 4 4 FY 2 0 4 5 FY 2 0 4 6 FY 2 0 4 7 FY 2 0 4 8 FY 2 0 4 9 FY 2 0 5 0 FY 2 0 5 1 FY 2 0 5 2 FY 2 0 5 3 FY 2 0 5 4 FY 2 0 5 5 2 E M e ta l P ro d u c e d ( k o z) 2 E R e c o v e ry ( % ) 2E Metal Produced 2E Recovery 165 14.2.1.7 Water Requirements The maximum water requirement for the Stillwater Concentrator when operating is 2 000gal per minute and demand ranges from 1 300gal to 2 000gal per minute. The Stillwater Concentrator water balance is water-positive, and the concentrator receives return water from the Hertzler TSF, as well as treated water from underground. The Nye TSF is used as the excess water storage facility. 14.2.1.8 Reagent Requirements -The process materials (reagents and steel balls) used in the Stillwater Concentrator are readily available and mostly sourced from credible suppliers located in the USA or North America. Reagents commonly used are potassium amyl xanthate, di-thiophosphate, carboxymethyl cellulose, methyl Isobutyl carbinol, and flocculant/coagulant. Hardened steel balls in 3-inch and 4-inch size are used in the primary grinding mills and are consumed at approximately 1lb/ton total. The Qualified Persons are satisfied that the measures in place in respect of the supply of process materials which should ensure security of supplies over the life of the operations East Boulder Concentrator 14.2.2.1 Plant Design and Equipment Specifications The East Boulder Concentrator was commissioned in 2001 as a 2 000-ton per operating day conventional crushing, milling, flotation, and filtration plant producing a PGM-base metal sulphide concentrate suitable for downstream smelting and refining. Primary crushing equipment consists of Metso (Nordberg) feeder and jaw crusher with a capacity 300 tons per operating hour. Primary grinding equipment consists of:  A Metso 2 000HP SAG mill charged with 4-inch hardened steel balls and with a capacity of 150 tons per operating hour;  A Metso 2 000HP ball mill charged with 3-inch hardened steel balls and with a capacity of 105 tons per operating hour.  The flotation circuit consists of:  Flash flotation circuit containing a Metso unit cell and Metso unit cell cleaner;  Rougher flotation consisting of ten Metso 5cft convention flotation cells;  Rougher-cleaner flotation circuit consisting of a 3ft Metso column flotation cell, four Metso 100cft conventional cleaner flotation cells, and four Metso 50cft conventional cleaner flotation cells;  Middling flotation circuit consisting of ten Metso 500cft conventional flotation cells;  Middling cleaner flotation circuit consisting of four Metso 100cft conventional cleaner flotation cells, and four Metso 50cft conventional cleaner flotation cells;  Scavenger flotation consisting of twelve Metso 500cft conventional flotation cells.  Scavenger cleaner flotation consisting of eight Metso 100cft conventional cleaner flotation cells and a 3ft column flotation cell. 166 Filtration equipment consists of a Metso-Outotec 8-plate pressure filter with a capacity of 100 tons concentrate per day (4 000 tons per day ore feed). 14.2.2.2 Plant Capacity The concentrator at East Boulder Mine was commissioned in 2001 as a 2 000-ton per operating day conventional crushing, milling and flotation plant producing. The design capacity of the concentrator is approximately 2 500 tons per operating day following several process modifications and expansions. This capacity is equivalent to an estimated 838 000 tons per year at 92% operational utilisation and sufficient for the LoM annual production targets. However, at the current 75% utilisation and 99% availability and operating on a four-crew schedule, the current capacity of the concentrator is approximately 2 400 tons per operating day. This capacity is equivalent to an estimated 650 000 tons per year, which is sufficient capacity for the planned production targets until FY2026. The concentrator will be operated at higher utilisation than currently to accommodate higher throughputs (up to 760 000 tons per annum) planned from FY2027 onwards. Prior to FY2017, the concentrator processed approximately 650 000 tons per year of RoM ore feed from the Frog Pond East and West Sections of East Boulder Mine and achieved total 2E recoveries of approximately 91%. Operating the plant below capacity necessitated a ten-day or eleven-day fortnight operating basis, with plant switch-off every second weekend resulting in approximately 75% utilisation. Due to a higher utilisation of the concentrator following the implementation of the Fill The Mill Project, the concentrator achieved peak production of 722 000 tons milled in FY2020. The Qualified Person notes the plan to sustain the budgeted recovery to an average 91% for the LoM should be achievable through metallurgical input and optimisation as before. Furthermore, the planned tonnage throughput peaking at approximately 760 000 tons per annum for the LoM is achievable considering that the annual targets are significantly below the 838 000 tons per year plant capacity at full operational utilisation. The upgraded concentrate handling facility which includes larger filter press and concentrate storage bin than were previously used and cater to side-tipping bulk trucks can handle the anticipated concentrate volumes. The side-tip trucks have the added advantage of also being usable for transporting slag or bricks from the Columbus Metallurgical Complex to the concentrators. 14.2.2.3 Manpower Requirements The plant staffing comprises three crews operating two 12-hour shifts of one Supervisor and three Concentrator Operators and one Heavy Equipment Operator per rotating crew as well as one Water Systems Operator. Maintenance is currently staffed with six Mechanical Technicians, two Electrical Technicians, one Maintenance General Foreman, one Maintenance Planner and one Supervisor, all of whom currently work on a five-day per week basis. Major and routine planned maintenance is scheduled for shut-down intervals lasting 12 to 36 hours twice per month, which has resulted in plant mechanical availability of more than 99%. These staffing levels


167 are adequate for the current levels of operation. The increase in throughput necessitated the appointment of a fourth shift and the transition to continuous operations. Therefore, planned maintenance shut-downs have been initiated to ensure plant availability is maintained. 14.2.2.4 Process Description The simplified block flow for the East Boulder Concentrator is presented in Figure 68. The process comprises open circuit crushing followed by two stages of milling, with the sized product being delivered to the flotation circuit. Various stages of flotation including roughing, cleaning and scavenging in addition to a regrind circuit ensure that recovery is optimised and concentrate grades suitable for smelting are realised. Figure 68: East Boulder Concentrator Simplified Block Flow Diagram 14.2.2.5 Production Plan The recent history and budget operational parameters for the East Boulder Concentrator are presented together with the LoM budget data for the East Boulder Concentrator in Table 44, Figure 70. The FY2021, FY2022 and FY2023 data presented reflects the actual annual performance whilst the FY2024 to FY2069 data represents current budget targets. The current operational methods and capacities are adequate. Metallurgical efficiencies projected have also been sustainably obtained historically and are thus reasonable budget targets. 168 Table 44: East Boulder Concentrator Actual and Forecast LoM Operational Throughput and Outputs The key variables reviewed for the LoM are presented in Figure 69 and Figure 70. Figure 69: East Boulder Concentrator Actual and Forecast LoM Operational Throughput and Outputs FY2021 FY2022 FY2023 FY2024 FY2025 FY2026 FY2027 FY2028 FY2029 FY2030 FY2031 FY2032 FY2033 FY2034 FY2035 FY2036 FY2037 Total Feed tons 720 033 545 873 565 820 631 438 647 381 638 411 686 999 686 999 686 999 686 999 686 999 686 999 686 999 671 059 714 577 678 052 687 946 Concentrate Produced tons 17 859 17 134 17 514 15 525 15 917 15 696 16 891 16 891 16 891 16 891 16 891 16 891 16 891 16 499 17 569 16 671 16 914 2E Recovery % 90.60 91.33 90.86 90.97 90.97 90.97 90.97 90.97 90.97 90.97 90.97 90.97 90.97 90.97 90.97 90.97 90.97 2E Metal Produced oz 223 842 160 925 164 349 184 766 184 717 195 915 216 260 216 260 216 260 216 260 216 260 216 260 216 260 219 552 219 815 213 991 214 473 FY2038 FY2039 FY2040 FY2041 FY2042 FY2043 FY2044 FY2045 FY2046 FY2047 FY2048 FY2049 FY2050 FY2051 FY2052 FY2053 FY2054 Total Feed tons 683 703 717 100 717 897 723 526 739 637 760 135 747 742 745 203 744 689 730 002 721 627 708 004 639 872 702 868 714 501 688 929 694 608 Concentrate Produced tons 16 810 17 631 17 651 17 789 18 185 18 689 18 384 18 322 18 309 17 948 17 742 17 407 15 732 17 281 17 567 16 938 17 078 2E Recovery % 90.97 90.97 90.97 90.97 90.97 90.97 90.97 90.97 90.97 90.97 90.97 90.97 90.97 90.97 90.97 90.97 90.97 2E Metal Produced oz 213 440 211 753 207 992 213 795 216 321 217 380 215 304 217 741 215 536 210 530 209 709 212 702 192 903 209 754 210 362 209 633 207 736 FY2055 FY2056 FY2057 FY2058 FY2059 FY2060 FY2061 FY2062 FY2063 FY2064 FY2065 FY2066 FY2067 FY2068 FY2069 Total Feed tons 643 795 675 016 719 184 681 280 698 783 671 549 677 236 674 942 655 452 699 749 721 315 739 214 728 286 747 472 405 497 Concentrate Produced tons 15 829 16 596 17 682 16 750 17 181 16 511 16 651 16 595 16 115 17 204 17 735 18 175 17 906 18 378 9 970 2E Recovery % 90.97 90.97 90.97 90.97 90.97 90.97 90.97 90.97 90.97 90.97 90.97 90.97 90.97 90.97 90.97 2E Metal Produced oz 191 450 202 039 215 233 204 135 214 302 212 925 214 280 211 355 210 040 214 951 213 704 214 700 211 346 213 581 121 641 Budget Budget Budget Parameter Unit Parameter Unit Actual Parameter Unit - 2 4 6 8 10 12 14 16 18 20 - 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 FY 2 0 2 1 FY 2 0 2 2 FY 2 0 2 3 FY 2 0 2 4 FY 2 0 2 5 FY 2 0 2 6 FY 2 0 2 7 FY 2 0 2 8 FY 2 0 2 9 FY 2 0 3 0 FY 2 0 3 1 FY 2 0 3 2 FY 2 0 3 3 FY 2 0 3 4 FY 2 0 3 5 FY 2 0 3 6 FY 2 0 3 7 FY 2 0 3 8 FY 2 0 3 9 FY 2 0 4 0 FY 2 0 4 1 FY 2 0 4 2 FY 2 0 4 3 FY 2 0 4 4 FY 2 0 4 5 FY 2 0 4 6 FY 2 0 4 7 FY 2 0 4 8 FY 2 0 4 9 FY 2 0 5 0 FY 2 0 5 1 FY 2 0 5 2 FY 2 0 5 3 FY 2 0 5 4 FY 2 0 5 5 FY 2 0 5 6 FY 2 0 5 7 FY 2 0 5 8 FY 2 0 5 9 FY 2 0 6 0 FY 2 0 6 1 FY 2 0 6 2 FY 2 0 6 3 FY 2 0 6 4 FY 2 0 6 5 FY 2 0 6 6 FY 2 0 6 7 FY 2 0 6 8 FY 2 0 6 9 FY 2 0 7 0 C o n c e n tr a te P ro d u c e d ( th o u sa n d t o n s) Fe e d ( th o u sa n d t o n s) Total Feed Concentrator Nameplate Capacity Concentrate Produced 169 Figure 70: East Boulder Concentrator Actual and Forecast LoM Operational Data 14.2.2.6 Energy Requirements The energy requirement for the East Boulder Concentrator is 4.5MW and is fed by a 20MW substation. The concentrator at East Boulder Mine is fed with power from a dedicated substation which comprises a 15/20MVA transformer. Sufficient power is available for the mill operations. 14.2.2.7 Water Requirements The water requirement for the East Boulder Concentrator when operating is 1200gal per minute. The overall mine water balance is water positive, requiring disposal of treated water. The concentrator utilises a combination of TSF return water and treated underground water for processing purposes. 14.2.2.8 Process Materials Requirements As is the case for the Stillwater Concentrator, the process materials (reagents and steel balls) used in the East Boulder Concentrator are readily available and mostly sourced from credible suppliers located in the USA or North America. Reagents commonly used are potassium amyl xanthate, di-thiophosphate, carboxymethyl cellulose, methyl Isobutyl carbinol, and flocculant/coagulant. Hardened steel balls in 3- inch and 4-inch size are used in the primary grinding mills and are consumed at approximately 1lb/ton total. The Qualified Persons are satisfied that the measures in place in respect of the supply of process materials which should ensure security of supplies over the life of the operations. 0 25 50 75 100 125 150 175 200 225 250 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 FY 2 0 2 1 FY 2 0 2 2 FY 2 0 2 3 FY 2 0 2 4 FY 2 0 2 5 FY 2 0 2 6 FY 2 0 2 7 FY 2 0 2 8 FY 2 0 2 9 FY 2 0 3 0 FY 2 0 3 1 FY 2 0 3 2 FY 2 0 3 3 FY 2 0 3 4 FY 2 0 3 5 FY 2 0 3 6 FY 2 0 3 7 FY 2 0 3 8 FY 2 0 3 9 FY 2 0 4 0 FY 2 0 4 1 FY 2 0 4 2 FY 2 0 4 3 FY 2 0 4 4 FY 2 0 4 5 FY 2 0 4 6 FY 2 0 4 7 FY 2 0 4 8 FY 2 0 4 9 FY 2 0 5 0 FY 2 0 5 1 FY 2 0 5 2 FY 2 0 5 3 FY 2 0 5 4 FY 2 0 5 5 FY 2 0 5 6 FY 2 0 5 7 FY 2 0 5 8 FY 2 0 5 9 FY 2 0 6 0 FY 2 0 6 1 FY 2 0 6 2 FY 2 0 6 3 FY 2 0 6 4 FY 2 0 6 5 FY 2 0 6 6 FY 2 0 6 7 FY 2 0 6 8 FY 2 0 6 9 FY 2 0 7 0 2 E M e ta l P ro d u c e d ( k o z) 2 E R e c o v e ry ( % ) 2E Metal Produced 2E Recovery 170 Concentrator Process Control Sampling The concentrators at Stillwater and East Boulder Mines carry out routine sampling at various stages of the process to produce the data required for the management of the processes and accounting for the metals processed. The samples are analysed at the Sibanye-Stillwater-owned and operated laboratory located at the Columbus Metallurgical Complex. Concentrator feed samples for Stillwater and East Boulder Mines are not taken at either concentrator due to the inclusion of flash flotation and gravity recovery processes within the milling circuit. This precludes representative sampling of the concentrator head feed stream and, as a result, concentrator metallurgical recoveries and plant head feed grades (which are the basis for Mineral Reserve grades reported) are back-calculated from feed mass, concentrate mass and grade, and tailings grade. The concentrate and tailings samples are taken at both concentrators using automated linear falling stream sample cutters. The samples are produced in duplicate using two stage rotary samplers on the concentrate thickener feed pipeline, resulting in a 24-hour composite sample, which is representative of the concentrator final product. This composite sample is not used for accounting purposes as the concentrate sample from the smelter is used for this purpose. Linear falling stream sample cutters also produce the primary tailings samples, which are reduced using two stage rotary tailings samplers at both plants to produce duplicate samples from the final float tails streams. This tailings material sampling process results in the production of a duplicate daily composite sample for analysis. The final tails material is then pumped to the sand plant in the case of the concentrator at East Boulder Mine, and the tailings dewatering section for the concentrator at Stillwater Mine. The laboratory analytical process followed for the concentrator samples resembles that employed for the geological samples described in Section 8 although the concentrate samples are processed in a separate line dedicated for the receiving, preparation and analysis of these high-grade samples. The sampling equipment and the sampling regimes in place are adequate and suitable for the operations. Sampling equipment for feed sampling at both the Stillwater and East Boulder Concentrators consists of vezin rotary hammer and rotary splitter supplied by FLSmidth which is capable of up to 250 samples per hour. Equipment for float feed, tailings sampling and metal accounting consists of rotary vezin cross- stream cutters supplied by FLSmidth which are capable of up 360 samples per hour. Equipment for smelter feed accounting consists of two-stage rotary vezin cross-stream cutters supplied by FLSmidth and these are capable of up to 250 samples per hour. The concentrate sample analyses are subsequently verified via the automated sampling process of the concentrate at the smelter and analysis at the laboratory. Smelting and Refining Background The Columbus Metallurgical Complex was commissioned in 1990 and focused on smelting concentrate from Stillwater Mine. Initially, a 30-ton concentrate per day smelting facility was installed, which was


171 subsequently replaced with a 100-ton per day unit in 1999. Prior to 1990, concentrate from the concentrator at Stillwater Mine (the only concentrator at the time) was exported to Belgium for toll treatment and refining. The smelting operations have been expanded over the years, with the diversity of the operations at the complex also expanded to include base metal refining and PGM autocatalytic converter recycling operations. Currently, the smelter beneficiates the primary PGM concentrate from Stillwater and East Boulder Mines as well as PGM autocatalytic material sourced from third parties. There have been modest capacity upgrades of various units of the smelter and refinery as part of the Blitz Project. Smelter 14.3.2.1 Design and Equipment Specifications The Smelter at the Columbus Metallurgical Complex was commissioned in 1990 as a 30-ton of concentrate per operating day plant producing a copper and nickel matte containing PGMs. The Smelter has been through several upgrades to its current capacity to 185-ton of concentrate and used automotive catalysts per operating day. The current configuration consists of a concentrate dryer supplier by Carrier Vibrating Equipment Inc, two electric submerged arc furnaces supplied by Hatch Ltd, two top blown rotary converters supplied by Metso-Outotech, and an off-gas treatment facility consisting of Dynawave scrubbers supplied by Monsanto Enviro-Chem. The process flow and description is presented in Section 14.3.2.3. 14.3.2.2 Capacity The smelter comprises of two 150-ton per day primary smelting electric furnaces (Electric Furnace #1 and Electric Furnace #2), both of which can be configured to operate in a primary role or alternatively with Furnace #2 in a primary role and Furnace #1 in a slag cleaning role. PGM concentrate averaging 11% to 13% moisture is received from the concentrators in 30-ton side-tipping trucks. The process flow and description is presented in Section 14.3.2.3. The following areas of the smelter have recently been upgraded with a view to increasing tonnage throughput capacity in response to production increases at Stillwater and East Boulder Mines:  Concentrate Receiving and Drying: A completely new concentrate receiving facility was designed and constructed. This allows delivery via side-tip trucks with the concentrate offloaded and rehandled into the feeding system via a dedicated front-end loader. A new fluid bed dryer has also been installed with a nominal capacity of approximately 320 tons per day. Both concentrate handling and drying facilities were commissioned in early FY2021;  Smelter and Gas Cleaning: Both Electric Furnace 1 and Electric Furnace 2 now operate in primary smelting duty at an installed power of 7.5MW each, with a combined feed capacity of 185 tons per day of dried concentrate. The gas handling facility did not require any upgrades to accommodate the increased furnace capacity and has demonstrated adequate capacity. Both Electrical Furnaces were supplied by Hatch and have been rebuilt since original install. Electric Furnace 1 was rebuilt in FY2021, and Electric Furnace 2 was rebuilt in FY2023;  Granulation: The slag handling methodology is such that top blown rotary converter slag and furnace slag materials are treated separately. While the furnace slag is cooled and returned to the Stillwater or East Boulder Mine Concentrators for re-milling, the converter slag is granulated at the smelter. This granulation facility has been redesigned for upgrade. The top blown rotary 172 converter matte dryer was installed during FY2021 and the electric furnace matte/top blown rotary converter slag dryer was installed in early FY2022. Both dryers were supplied by Carrier Vibrating Equipment, Inc;  Top Blown Rotary Converters: The existing two top blown rotary converters were supplied by Metso-Outotech and have been upgraded to larger drums, which has resulted in larger charge capacity and longer blowing time. This has also increased overall converting capacity by reducing converter downtimes. The converter upgrades were completed during FY2022; and  Regeneration: Sulphur dioxide off gas is captured by way of 2 primary Dynawave scrubbers and a secondary Dynawave scrubber supplied by Monsanto Enviro-Chem. Additionally, to maintain the Columbus Metallurgical Complex’s permitted sulphur dioxide discharge level in the final atmospheric discharge gas, an additional sodium hydroxide regeneration train was installed. This unit modifies the scrubber liquor with the addition of further NaOH and subsequent addition of hydrated lime, which precipitates a gypsum product (CaSO4.2H2O), which is sold as an agricultural soil modifier and regenerates the NaOH for reuse in the scrubber circuits. The additional caustic regeneration train is a duplicate of the existing trains and is fully operational. 14.3.2.3 Process Description The simplified process flow block diagram for the smelter processes is presented in Figure 71. The concentrate bins delivered to the smelter are sampled, where after the concentrate is discharged via an elevator system into a fluidised bed dryer. Natural gas is available at the Columbus Metallurgical Complex site as a piped utility and, as such, is used wherever possible as a heating source. The dryer is thus natural gas fired and reduces the concentrate moisture to below 1%. Used automotive catalysts, which average 70oz 2E per ton, are combined with the new concentrate feed after the dryer. The treatment and processing of recycle materials is addressed in Section 21.1. High-temperature furnace fume and process gases from the electric furnace roof extraction system enter a primary bag house, whilst the lower temperature gas and particulates from the tapping, converting and granulation processes enter a secondary baghouse. The baghouses use high- performance Gore-Tex coated membrane bags to capture the particulates, which are recycled back to the furnace feed hoppers via a pneumatic conveying system. Matte produced from the arc furnaces is granulated and then charged into the top-blown rotary converter (TBRC), where the sulphur and iron components are oxidised. The slag from this process is recycled to the furnaces. The matte typically contains 350oz 2E per ton to 700oz 2E per ton, 28% to 30% Cu, 40% to 42% Ni, 20% to 22% S, 2% iron (Fe) and the balance comprising cobalt (Co), gold (Au), silver (Ag), Rh, tellurium (Te) and selenium (Se). 173 Figure 71: A Simplified Block Flow Diagram of the Smelter 14.3.2.4 Process Control Sampling All concentrate transfers to the smelter from the two concentrators are sampled using a pipe sampler on a grid pattern prior to offloading. A final composite sample per shipment with an ultimate sample mass of approximately 10lbs is then transported to the in-house laboratory. This sample provides the definitive analysis for the concentrate from the concentrators, which is used in the metallurgical accounting process. All catalyst material received at the smelter is sampled and prepared separately from the concentrate. The material is either sampled using a pipe sampler or TEMA sampler. These samples are then transported to the in-house laboratory. The sample provides definitive analysis for the catalyst from recycled material, which is used in the metallurgical accounting process. Converter matte, once granulated, is the smelter final product and is sampled at the smelter by a falling stream sampler (supplied by Salina Vortex Corp.) at the granulator. A primary sample is taken, which is reduced to approximately 2lb via a twelve-point rotary splitter (supplied by Eriez Manufacturing Co.) before being manually delivered as a duplicate sample to the in-house laboratory. This sample provides the definitive analysis for the convertor matte from the smelter, which is used in the metallurgical accounting process. The laboratory analysis process flow for smelter samples resembles that for the geological samples described in Section 8, although the converter matte and concentrate samples are processed in a separate line dedicated for the receiving, preparation and analysis of high-grade samples. Other samples produced by the smelter for analysis at the analytical laboratory, which are utilised for internal accounting purposes, are as follows:  Furnace slag: spoon samples are taken during the tapping process and composited daily; 174  Converter slag: converter slag is grab sampled from each bin produced for recycle back to the furnaces, and composited on a daily and weekly basis;  Furnace matte: furnace matte is grab sampled from each bin produced and composited on a daily and weekly basis; and  Gypsum product: gypsum product is pipe-sampled from each weekly composite sample container bin resulting in a bulk sample, which is dried and incrementally split for analysis of the final aliquot. The sampling equipment and the sampling regimes in place at the smelter are adequate and suitable for the operations. 14.3.2.5 Production Plan The recent history and budget operational parameters for the smelter plant have been reviewed and the key variables are presented in Table 45, Figure 72 and Figure 73. The FY2021, FY2022 and FY2023 data presented reflects the actual annual performance whilst the FY2024 to FY2069 data represents the current budget targets. Metallurgical efficiencies projected have also been sustainably obtained historically and are thus reasonable budget targets. The increases in smelter operational duty planned are visible whilst the other key variables such as smelter first pass recovery and recycle tons treated remain at levels previously achieved. The increases in concentrate feed will be achieved with both electric furnaces operating in primary duty, whilst the implemented upgrades to concentrate receiving and drying and the larger converter drums will match this capacity. Table 45: Smelter Historical and Budget Operational Data FY2021 FY2022 FY2023 FY2024 FY2025 FY2026 FY2027 FY2028 FY2029 FY2030 FY2031 FY2032 FY2033 FY2034 FY2035 FY2036 FY2037 Smelter Concentrate Feed tons 40 393 34 075 35 483 38 384 38 328 41 895 44 543 48 087 50 059 50 615 50 735 50 812 50 759 50 284 51 429 50 538 50 732 Smelter Recycle Feed tons 9 561 7 579 4 245 4 392 7 300 9 904 11 193 12 166 11 968 12 793 11 297 11 010 11 113 10 157 10 171 8 853 8 767 Converter Matte Produced tons 2 031 1 469 1 445 1 744 1 723 1 985 2 243 2 431 2 398 2 564 2 264 2 200 2 227 2 035 2 038 1 769 1 757 Smelter 1st Pass Recovery % 97.37 97.85 97.97 97.60 97.20 97.02 96.92 96.91 96.94 96.90 96.96 96.99 96.99 97.04 97.06 97.13 97.15 Total 2E Recovered oz 1 257 205 971 139 725 236 769 015 949 220 1 210 113 1 371 232 1 493 225 1 514 986 1 580 647 1 495 409 1 470 477 1 470 217 1 401 984 1 407 667 1 310 835 1 302 144 FY2038 FY2039 FY2040 FY2041 FY2042 FY2043 FY2044 FY2045 FY2046 FY2047 FY2048 FY2049 FY2050 FY2051 FY2052 FY2053 FY2054 Smelter Concentrate Feed tons 50 625 51 402 51 405 51 552 51 943 52 526 52 244 52 301 52 046 51 723 51 516 51 215 49 492 51 119 51 379 48 957 30 808 Smelter Recycle Feed tons 9 872 10 134 10 049 10 190 10 341 10 204 9 839 9 762 8 416 8 346 8 452 9 911 9 541 10 024 10 146 9 014 6 382 Converter Matte Produced tons 1 978 2 031 2 008 2 042 2 072 2 045 1 966 1 956 1 686 1 672 1 689 1 986 1 912 2 009 2 028 1 806 1 279 Smelter 1st Pass Recovery % 97.08 97.09 97.10 97.11 97.11 97.11 97.12 97.14 97.25 97.24 97.24 97.10 97.10 97.03 97.06 97.01 97.02 Total 2E Recovered oz 1 370 043 1 389 648 1 382 631 1 379 113 1 389 496 1 399 239 1 378 052 1 369 177 1 263 947 1 258 208 1 260 214 1 374 558 1 324 595 1 418 894 1 405 731 1 360 666 871 144 FY2055 FY2056 FY2057 FY2058 FY2059 FY2060 FY2061 FY2062 FY2063 FY2064 FY2065 FY2066 FY2067 FY2068 FY2069 Smelter Concentrate Feed tons 16 256 17 045 18 160 17 203 17 648 16 963 17 106 17 047 16 557 17 672 18 213 18 663 18 387 18 870 10 239 Smelter Recycle Feed tons 4 115 4 355 4 626 4 388 4 606 4 589 4 606 4 543 4 515 4 633 4 593 4 615 4 543 4 603 2 615 Converter Matte Produced tons 825 870 927 879 923 917 923 910 905 926 920 925 910 920 524 Smelter 1st Pass Recovery % 97.05 97.03 97.04 97.03 97.00 96.95 96.95 96.97 96.93 96.99 97.05 97.08 97.08 97.11 97.03 Total 2E Recovered oz 469 982 496 764 528 352 501 105 526 010 523 405 525 887 518 733 515 457 528 453 524 621 527 112 518 880 525 252 298 600 Budget Budget Budget Parameter Unit Parameter Unit Actual Parameter Unit


175 Figure 72: Smelter Actual and Forecast LoM Operational Throughput Figure 73: Smelter LoM Operational Performance, Actual and Forecast 0 250 500 750 1 000 1 250 1 500 1 750 2 000 2 250 2 500 2 750 0 5 000 10 000 15 000 20 000 25 000 30 000 35 000 40 000 45 000 50 000 55 000 60 000 65 000 70 000 FY 2 0 2 1 FY 2 0 2 2 FY 2 0 2 3 FY 2 0 2 4 FY 2 0 2 5 FY 2 0 2 6 FY 2 0 2 7 FY 2 0 2 8 FY 2 0 2 9 FY 2 0 3 0 FY 2 0 3 1 FY 2 0 3 2 FY 2 0 3 3 FY 2 0 3 4 FY 2 0 3 5 FY 2 0 3 6 FY 2 0 3 7 FY 2 0 3 8 FY 2 0 3 9 FY 2 0 4 0 FY 2 0 4 1 FY 2 0 4 2 FY 2 0 4 3 FY 2 0 4 4 FY 2 0 4 5 FY 2 0 4 6 FY 2 0 4 7 FY 2 0 4 8 FY 2 0 4 9 FY 2 0 5 0 FY 2 0 5 1 FY 2 0 5 2 FY 2 0 5 3 FY 2 0 5 4 FY 2 0 5 5 FY 2 0 5 6 FY 2 0 5 7 FY 2 0 5 8 FY 2 0 5 9 FY 2 0 6 0 FY 2 0 6 1 FY 2 0 6 2 FY 2 0 6 3 FY 2 0 6 4 FY 2 0 6 5 FY 2 0 6 6 FY 2 0 6 7 FY 2 0 6 8 FY 2 0 6 9 FY 2 0 7 0 M a tt e P ro d u c e d ( to n s) Fe e d ( to n s) Smelter Concentrate Feed Smelter Recycle Feed Converter Matte Produced 0 200 400 600 800 1 000 1 200 1 400 1 600 1 800 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 FY 2 0 2 1 FY 2 0 2 3 FY 2 0 2 5 FY 2 0 2 7 FY 2 0 2 9 FY 2 0 3 1 FY 2 0 3 3 FY 2 0 3 5 FY 2 0 3 7 FY 2 0 3 9 FY 2 0 4 1 FY 2 0 4 3 FY 2 0 4 5 FY 2 0 4 7 FY 2 0 4 9 FY 2 0 5 1 FY 2 0 5 3 FY 2 0 5 5 FY 2 0 5 7 FY 2 0 5 9 FY 2 0 6 1 FY 2 0 6 3 FY 2 0 6 5 FY 2 0 6 7 FY 2 0 6 9 2 E R e c o v e re d ( k o z) 2 E R e c o v e ry ( % ) New Feed 2E Recovered Recycle Feed 2E Recovered Smelter 1st Pass Recovery 176 14.3.2.6 Manpower Requirements The budgeted total smelter manpower complement is 96 consisting of 43 hourly and 14 salaried employees in operations and 28 hourly and 11 salaried employees in maintenance. 14.3.2.7 Energy Requirements The energy requirement for the smelter is approximately 11MW. Power is supplied to the Columbus Metallurgical Complex via a dedicated switching station containing two transformers. The power supply is adequate for both the smelting and base metal refining operations. 14.3.2.8 Water Requirements The water requirement for the smelter is 21Mgals/yr. The entire Columbus Metallurgical Complex is water neutral, with sufficient recycle and storage facilities included. The water supply is adequate for both the smelting and base metal refining operations. 14.3.2.9 Flux and Other Requirements The process materials (e.g., flux) used in the smelting operations are readily available. Typical smelter process materials are catalyst (recycle material), limestone, taconite, quick lime, oxygen, hydrated lime, caustic, and flocculant. Most sources are domestic in nature and the overseas sources have been studied intensely to evaluate secondary and tertiary sources in case of supply chain interruption from the primary source. The Qualified Persons are satisfied with security of supplies in respect of process materials for the smelting operations over the life of operations. Base Metal Refinery 14.3.3.1 Design and Equipment Specifications The Base Metals Refinery (BMR) at the Columbus Metallurgical Complex was commissioned in 1996 as a 660 pounds of smelter matte per hour plant producing PGM filter cake. Since commissioning, the BMR has been upgraded to increase capacity the current level of 1 300 pounds of smelter matte per hour. The current configuration consists of the nickel atmospheric leach circuit, a copper dissolve autoclave designed by Hatch Ltd, a nickel sulfate crystallizer supplied by Swenson Technology Inc, a copper electrowinning plant, and two polish leach autoclaves designed by Bateman Engineering. The detailed process flow and description is presented in Section 14.3.3.3. 14.3.3.2 Capacity The BMR facility was installed in 1996 at a nameplate capacity of 660lbs per hour but has a current capacity of more than 1 200lb per hour of granulated matte due to some process expansions – primarily a result of process optimisation and improvement. The BMR currently operates on two 12-hour shifts continuously from Monday morning to Thursday afternoon (equivalent to 80 hours per week or a utilisation of 47.6%). The copper electrowinning circuit at the facility, which operates continuously, was 177 expanded in FY2021 by adding six cells to eliminate a bottleneck that occurred historically in the BMR process. The expanded processing capacity can produce 750 tons per year of copper, with spare capacity remaining. The BMR process flow and description is presented in Section 14.3.3.3. The Qualified Person Is also of the view that, with the current matte capacity exceeding 1 200lb per hour and the expanded copper electrowinning circuit, the forecast matte volumes and nickel processing capacity can be accommodated through the existing operational schedule, with occasional overtime to cover any variance. 14.3.3.3 Process Description The granulated converter matte product is weighed upon receipt at the BMR facility. The matte is milled and leached with sulphuric acid and oxygen at atmospheric conditions to remove nickel as a sulphate crystal product. The remaining solids from the nickel leach are then leached with sulphuric acid and oxygen under pressurized conditions to dissolve copper with some selenium (Se) and tellurium (Te) dissolved in the process. The latter two metals are cemented out of solution, leaving the copper solution for electrowinning. The solids remaining after copper dissolution forms the PGM filter cake, which is washed, filtered and dried. The simplified process flow block diagram for the BMR processes is presented in Figure 74. The final product (filter cake) is despatched to Johnson Matthey Company (Johnson Matthey) for further separation and refining. 178 Figure 74: A Simplified Block Flow Diagram of the Base Metal Refinery 14.3.3.4 Process Control Sampling The converter matte bins received from the smelter at the BMR are weighed and the mass becomes the final value used in the metal accounting system. The analysis used in the accounting system originates from the final smelter sample. BMR products are all sampled within the production process and the products are analysed for quality control purposes only as follows:  NiSO4 crystals: A primary sample is taken from the bagging process via a rotary splitter, which is reduced further for final analysis;  Copper cathode: This is sampled by drilling of the cathode plate, digested and analysed by ICP spectrometry for the copper turnings produced, and the analysis is used as the dispatch analysis for the cathode product; and  PGM filter cake: This is the final BMR product shipped to Johnson Matthey for further refining. This material is sampled at the final product dryer by a rotary splitter and is then sub-sampled. Duplicate samples are produced, and the analytical results of these samples become the invoice analyses for the shipments.


179 The invoiced analysis is checked by Johnson Matthey on receipt, in addition to which there is an umpire process, which is followed for variances greater than those allowed in the contract. The in-house laboratory reports quarterly on the correlations achieved between analyses from Johnson Matthey, in- house and umpire laboratories (where required) on a per element basis. The BMR sample analysis process also resembles that for the geological samples described in Section 8 although the filter cake, converter matte and concentrate samples are processed in a separate line dedicated for the receiving, preparation and analysis of high-grade samples. The main sampling point in the BMR is for the PGM filtercake. This process utilizes a rotary splitter supplied by Verder Scientific, and the sampling equipment and the sampling regimes in place at the BMR are adequate and suitable for the operations 14.3.3.5 Manpower Requirements The total BMR manpower complement is 34 consisting of 16 hourly and 6 salaried employees in operations and 9 hourly and 3 salaried employees in maintenance. 14.3.3.6 Energy Requirements The energy requirement for the BMR is approximately 1MW. Power is supplied to the Columbus Metallurgical Complex via a dedicated switching station containing two transformers. The power supply is adequate for all base metal refining operations. 14.3.3.7 Water Requirements The water requirement for the BMR is approximately 9Mgals/yr. The entire Columbus Metallurgical Complex is water neutral, with sufficient recycle and storage facilities included. The water supply is adequate for all base metal refining operations 14.3.3.8 Process Materials Requirements The process materials (reagents) used in the BMR are also readily available and sourced from credible domestic suppliers. Typical reagents used are sulfuric acid, oxygen, chopped recycled copper wire, EW smoothing agent (polyacrylic acid), and flocculant. The Qualified Persons are satisfied that the measures in place in respect of the supply of process materials which should ensure security of supplies over the life of the operations. 14.3.3.9 Production Plan The recent history and budget operational parameters for the BMR have been reviewed and the key variables are presented in Table 46, Figure 75 and Figure 76. The FY2021, FY2022, and FY2023 data presented reflects the actual annual performance whilst the FY2024 to FY2069 data presents the current LoM budget targets. The Qualified Person is of the view that the current operational methods and 180 capacities are adequate. Furthermore, the metallurgical recoveries projected have also been sustainably obtained historically and are reasonable budget targets. Table 46: Base Metal Refinery Historical and Forecast LoM Operational Data Figure 75: Base Metal Refinery Actual and Forecast LoM Operational Throughput and Base Metals Recovered FY2021 FY2022 FY2023 FY2024 FY2025 FY2026 FY2027 FY2028 FY2029 FY2030 FY2031 FY2032 FY2033 FY2034 FY2035 FY2036 FY2037 BMR Matte Feed tons 2 043 1 469 1 435 1 744 1 723 1 985 2 243 2 431 2 398 2 564 2 264 2 200 2 227 2 035 2 038 1 769 1 757 Cu Produced tons 551 419 390 479 472 546 624 680 663 720 621 602 608 569 570 479 474 Ni Produced tons 900 669 630 755 749 859 963 1 040 1 034 1 094 982 956 968 872 873 773 770 Total 2E Recovered oz 1 255 404 983 922 729 683 768 253 950 661 1 207 693 1 368 490 1 490 238 1 511 956 1 577 486 1 492 418 1 467 536 1 467 277 1 399 180 1 404 851 1 308 213 1 299 540 PGM Recovery % 99.80 99.80 99.80 99.80 99.80 99.80 99.80 99.80 99.80 99.80 99.80 99.80 99.80 99.80 99.80 99.80 99.80 FY2038 FY2039 FY2040 FY2041 FY2042 FY2043 FY2044 FY2045 FY2046 FY2047 FY2048 FY2049 FY2050 FY2051 FY2052 FY2053 FY2054 BMR Matte Feed tons 1 978 2 031 2 008 2 042 2 072 2 045 1 966 1 956 1 686 1 672 1 689 1 986 1 912 2 009 2 028 1 806 1 279 Cu Produced tons 550 567 560 569 578 571 547 543 440 436 444 553 530 562 568 505 372 Ni Produced tons 850 871 861 876 888 876 845 841 755 749 752 853 823 859 867 773 533 Total 2E Recovered oz 1 367 303 1 386 869 1 379 865 1 376 355 1 386 717 1 396 441 1 375 295 1 366 438 1 261 419 1 255 691 1 257 693 1 371 808 1 321 946 1 416 056 1 402 920 1 357 945 869 402 PGM Recovery % 99.80 99.80 99.80 99.80 99.80 99.80 99.80 99.80 99.80 99.80 99.80 99.80 99.80 99.80 99.80 99.80 99.80 FY2055 FY2056 FY2057 FY2058 FY2059 FY2060 FY2061 FY2062 FY2063 FY2064 FY2065 FY2066 FY2067 FY2068 FY2069 BMR Matte Feed tons 825 870 927 879 923 917 923 910 905 926 920 925 910 920 524 Cu Produced tons 252 266 284 269 283 281 283 279 277 283 282 283 279 282 160 Ni Produced tons 330 348 371 352 370 367 370 365 362 371 369 370 365 368 210 Total 2E Recovered oz 469 042 495 771 527 295 500 103 524 958 522 358 524 835 517 696 514 426 527 396 523 572 526 058 517 842 524 202 298 003 PGM Recovery % 99.80 99.80 99.80 99.80 99.80 99.80 99.80 99.80 99.80 99.80 99.80 99.80 99.80 99.80 99.80 Parameter Unit Parameter Unit Actual Parameter Unit Budget Budget Budget 0 100 200 300 400 500 600 700 800 900 1 000 1 100 1 200 0 200 400 600 800 1 000 1 200 1 400 1 600 1 800 2 000 2 200 2 400 2 600 2 800 FY 2 0 2 1 FY 2 0 2 2 FY 2 0 2 3 FY 2 0 2 4 FY 2 0 2 5 FY 2 0 2 6 FY 2 0 2 7 FY 2 0 2 8 FY 2 0 2 9 FY 2 0 3 0 FY 2 0 3 1 FY 2 0 3 2 FY 2 0 3 3 FY 2 0 3 4 FY 2 0 3 5 FY 2 0 3 6 FY 2 0 3 7 FY 2 0 3 8 FY 2 0 3 9 FY 2 0 4 0 FY 2 0 4 1 FY 2 0 4 2 FY 2 0 4 3 FY 2 0 4 4 FY 2 0 4 5 FY 2 0 4 6 FY 2 0 4 7 FY 2 0 4 8 FY 2 0 4 9 FY 2 0 5 0 FY 2 0 5 1 FY 2 0 5 2 FY 2 0 5 3 FY 2 0 5 4 FY 2 0 5 5 FY 2 0 5 6 FY 2 0 5 7 FY 2 0 5 8 FY 2 0 5 9 FY 2 0 6 0 FY 2 0 6 1 FY 2 0 6 2 FY 2 0 6 3 FY 2 0 6 4 FY 2 0 6 5 FY 2 0 6 6 FY 2 0 6 7 FY 2 0 6 8 FY 2 0 6 9 FY 2 0 7 0 M e ta l P ro d u c e d ( to n s) B M R M a tt e F e e d ( to n s) BMR Matte Feed Cu Produced Ni Produced 181 Figure 76: Base Metal Refinery Actual and Forecast LoM Operational Performance PGM Prill Splits Sibanye-Stillwater measures and reports metal prill splits as a ratio of palladium to platinum in the various intermediate products from the individual operations. The current ratios based on data for the FY2023 period have been reviewed by the Qualified Person. The Pd and Pt prill split percentages, based on the Pd:Pt ratio in concentrate resulting from the processing of ore from Stillwater and Easter Boulder Mines, are presented in Table 47. These have also been utilised for business and LoM planning. Table 47: Summary of Pt and Pd Prill Split Data Mine Pd: Pt Ratio Prill Split FY2023 Pt Pd Stillwater Mine 3.51:1 22.17% 77.83% East Boulder Mine 3.60:1 21.73% 78.27% Processing Logistics Concentrate from both the Stillwater and East Boulder Concentrators, with moisture content of 11% to 13%, is trucked via side-tipper bulk trucks to the smelter. Travel time for the concentrate truck from East Boulder Mine to the smelter by road is approximately two to three hours but the travel time for the concentrate truck from Stillwater Mine to the smelter is approximately one and a half hours. Following tube sampling for moisture and initial assays, the material is introduced into a fluidised bed, natural gas dryer that reduces moisture to less than 1%. The dried concentrate is conveyed to a feed storage bin and sampled in duplicate. 0 100 200 300 400 500 600 700 800 900 1 000 1 100 1 200 1 300 1 400 1 500 1 600 94.0 94.5 95.0 95.5 96.0 96.5 97.0 97.5 98.0 98.5 99.0 99.5 100.0 FY 2 0 2 1 FY 2 0 2 2 FY 2 0 2 3 FY 2 0 2 4 FY 2 0 2 5 FY 2 0 2 6 FY 2 0 2 7 FY 2 0 2 8 FY 2 0 2 9 FY 2 0 3 0 FY 2 0 3 1 FY 2 0 3 2 FY 2 0 3 3 FY 2 0 3 4 FY 2 0 3 5 FY 2 0 3 6 FY 2 0 3 7 FY 2 0 3 8 FY 2 0 3 9 FY 2 0 4 0 FY 2 0 4 1 FY 2 0 4 2 FY 2 0 4 3 FY 2 0 4 4 FY 2 0 4 5 FY 2 0 4 6 FY 2 0 4 7 FY 2 0 4 8 FY 2 0 4 9 FY 2 0 5 0 FY 2 0 5 1 FY 2 0 5 2 FY 2 0 5 3 FY 2 0 5 4 FY 2 0 5 5 FY 2 0 5 6 FY 2 0 5 7 FY 2 0 5 8 FY 2 0 5 9 FY 2 0 6 0 FY 2 0 6 1 FY 2 0 6 2 FY 2 0 6 3 FY 2 0 6 4 FY 2 0 6 5 FY 2 0 6 6 FY 2 0 6 7 FY 2 0 6 8 FY 2 0 6 9 FY 2 0 7 0 2 E R e c o v e re d ( k o z) 2 E R e c o v e ry ( % ) Total 2E Recovered PGM Recovery 182 Recycled automotive catalysts and other PGM-bearing materials, averaging 70oz 2E per ton, constitute a separate source of smelter feed. This is delivered to the smelter by clients in 3ft cube bags and boxes. This material is pulverised, sorted and sampled in the same manner prior to smelting to ensure client custom metal is accounted separately. All slag from the smelter as well as from the furnace and Top Blown Rotary Converter used lining bricks is sampled to quantify residual precious metals and returned to both the Stillwater and East Boulder Concentrators. The slag is transported via the return haul for the side-tipper trucks for re-milling to ensure residual metals are returned to the value stream. The residual metals are also accounted for in terms of the concentrator recovery performance measurement.


183 INFRASTRUCTURE Stillwater Mine Complex Concentrator Infrastructure The processing plant infrastructure at Stillwater Mine was built in 1987 and is in a good operational condition. Historical budgets have provided for adequate sustaining and project capital for maintenance and upgrades of plant infrastructure to ensure sustained performance at the required capacities. The planned maintenance of the Stillwater Concentrator follows the JD Edwards Maintenance Control system. Power supply to the concentrator plant is described in Section 15.1.4. As the Stillwater Concentrator is being upgraded to accommodate the increased capacity resulting from the Blitz expansion (Stillwater East Section), the power supply has also been upgraded accordingly. The concentrate handling thickener building and concentrate handling loadout building were completed and commissioned in FY2021. Several additional buildings are planned as part of the Concentrator Expansion to be completed in F2022 and these include the following:  Hertzler Overflow (O/F) tank and pump building;  Hertzler Motor Control Centre (MCC) expansion building;  5150 process water expansion building;  Ore handling building; and  Grinding building. Tailings Storage Facilities The TSFs for Stillwater Mine are at the mature stage. Stillwater Mine has moved the production deposition from the original Nye TSF to the Hertzler TSF. The Hertzler TSF is permitted to Stage 3 (equivalent to a height of 5 030ftmamsl), after which additional permitting will be required following a revised design. The current plan is to increase the capacity of the Hertzler TSF with new, additional tailings storage (Cells 4 and 5), to accommodate the increased production rate arising following additional material from the Stillwater East Section. The TSF is inspected by independent consultants on an annual basis, with Knight- Piésold being the defined Engineer-of-Record. The TSFs at the Stillwater Mine comprises two slimes impoundments, namely the Nye TSF (no longer in full- time use) and the Hertzler TSF (current primary storage). The Nye TSF was used from the start of the mine until 2002 when the Hertzler TSF was commissioned, and it is currently undergoing capping for closure by the end of FY2024. The Hertzler TSF is currently permitted to an elevation of 5 030ft including freeboard and supernatant pond, which is the maximum extent of the current Stage 3 embankment raise. Concentrator tailings are sampled and pumped to a paste plant alongside the Nye TSF located to the southwest of the concentrator. The paste plant, which is used on a limited basis, operates as a staging point for whole tailings slurry. The tailings may be routed from the paste plant either to the 5150 Level underground sand plant or to the Hertzler Pump House, from where it can be routed to either of the 184 other sand plants or the Hertzler TSF. Tailings can also be routed to the Nye TSF from the concentrator, the paste plant or the pump house, if required. Whole tailings material is classified at the underground sand plants into coarse sand and slimes fractions, the sand remains underground and is pumped into stopes for backfilling purposes, whilst the slimes fraction is pumped back to the pump house. The slime is then pumped via two eight-inch pipelines to the Hertzler TSF for deposition. Deposition on the Hertzler TSF is via periodic rotational discharge of tailings slurry around the perimeter of the facility using a group of spigots. Once a localised tailings beach has formed, deposition is transferred to another group of spigots at a different location. Water reclamation is achieved via two inclined reclaim pumps located at the south end of the TSF, which return process water to the concentrator. The adjacent Land Application and Disposal (LAD) pond to the west of the Hertzler Tailings Storage Facility is used to manage treated mine water volumes. The TSF is geomembrane lined, and the liner is routinely inspected by the Engineer of Record and an Independent Tailings Review Board, where possible. Basin underdrain and seepage measurement is performed and monitored via vibrating wire piezometers, whilst embankment crest-mounted survey monuments are used to measure slope slippage or movement. Additional inclinometers are installed around the base of the impoundment to monitor deeper ground movement and displacement. The basin underdrain pore pressures are monitored on a weekly basis via the piezometers, and these respond quickly to changes in the basin underdrain pumping rate. This results in changes in the tailings mass consolidation and hence maximises storage availability and assists in long-term closure planning. The concentrator performs weekly, monthly and quarterly TSF inspections and monitoring per its standard procedures, which are reviewed as part of the annual independent Engineer of Record inspection of the TSF performed by Knight-Piésold of Canada. The inspections and monitoring are required by the 2015 Montana Metal Mine Reclamation Act (MCA). The most recent inspection was performed in September 2023, with a review period from October 2022 to September 2023. No material issues were identified, but a corrective action plan for the issues which were identified was developed and submitted to the Montana Department of Environmental Quality (MDEQ) as required and in compliance with the MCA. The Nye TSF, located immediately to the south of the mining and processing complex, was decommissioned as the primary storage facility in 2001 but is used for emergency tailings storage and water management purposes. Supernatant water is recycled to the concentrator as process water via an inclined retractable pump at the north end of the facility. Survey beacons are in place and are routinely measured for slope stability and slippage. The most recent inspection of the TSF by Knight- Piésold raised no material findings. Knight-Piésold has been retained to develop a closure and rehabilitation plan for the Nye TSF. Capping of the Nye TSF commenced in late FY2018 and is expected to be completed by FY2024. 185 Stage 3 of the Hertzler TSF was completed in 2015 and filling of Stage 3 is currently underway. As part of the annual inspection of the Hertzler TSF, Knight-Piésold calculates a projected fill rate of the current and planned TSF capacity as an elevation above mean sea level by year. Knight-Piésold’s latest TSF filling calculations contained in the 2023 Annual Inspection Report estimates the Stage 3 limit of 5 030ftmsl to be reached (based on pond elevation) by April 2031(Figure 77) at the envisaged RoM ore production rates. The Qualified Person is satisfied with Knight-Piésold’s estimate of the Stage 3 capacity of Stage 3. Figure 77: Hertzler TSF Knight-Piésold Calculated Elevation Profile Stage 3 is currently the maximum permitted height of the Hertzler TSF and, as a result, operation of the TSF beyond this stage will require the design and approval of a Stage 4. A Plan of Operations Amendment for the Stage 4 and Stage 5 TSF expansions has been prepared and was submitted for agency approval in April 2023. Hertzler TSF expansion involves an initial capital expenditure amount of $6.5 million for studies over the FY2024 to FY2026 period and follow up expenditure of $135.4 million for detailed design and construction between FY2029 and FY2031, which have been budgeted for as discussed in Section 18.2.2.4. The Qualified Person deems the quantum of the capital budget to be sufficient for the implementation of the Hertzler TSF expansion. Sibanye-Stillwater has indicated to the Qualified Person that there are no 186 apparent impediments anticipated that will prevent the approval of the Hertzler TSF expansion. However, if the approval is declined and a new TSF is required, a timeframe of approximately three to five years for environmental permitting processes and two years for construction would be required. In addition, a higher capital budget provision than the current provision may be required. East Waste Rock Storage Facility The current East Waste Rock Storage Facility at Stillwater Mine is projected to reach capacity in Q4 FY2030 in conjunction with waste rock capping and closure of the Nye TSF. As a result, an expansion of the East Waste Rock Storage Facility has been designed, proposed, and included in the Amendment 14 Operating Permit application for Stillwater Mine. The Amendment 14 application was submitted in November 2023 and will be subject to an Environmental Impact Statement review and associated State and Federal permitting. It is expected that the Record of Decision and Permit will be issued no later than FY2028. Construction of the expansion area is currently targeted to begin in FY2029 with completion and ability to accept waste rock storage starting in FY2031. The project involves approximately $20 million of capital expenditure. The East Side Waste Rock Storage Facility expansion includes a 56-acre extension to the northeast along with a 200ft increase in the height of the overall facility. Based on current LoM plan, the facility is designed to contain 35 years of waste rock storage. Power Stillwater Mine receives power from North West Energy from a substation located adjacent to the mine site. It receives power from the grid via two sources as follows:  100kV line via the Columbus-Rapelje Auto-substation; and  100kV line via Chrome Junction Substation. The powerline from Chrome Junction to Stillwater Mine is a radial feed at 100kV and feeds three small substations belonging to Beartooth Electric. The Nye REA Tap substation feeds the Hertzler TSF. The mine site has two main substations, namely the West Substation and East Substation, both connected to North West Energy’s substation adjacent to the mine via a 100KV line. The West Substation is owned and maintained by North West Energy and feeds most of the existing mine site including the concentrator. The East Substation is owned and maintained by Stillwater Mine and was installed as part of the Blitz Project to power the Stillwater East Section. The actual power demand loads for Stillwater Mine are as follows:  West Substation: 20MW at 0.92 Power Factor, with current load capacity of approximately 109% without fans and 82% with fans;  East Substation: 12.5MW at 0.88 Power Factor; and  Monthly maximum peak for the site: 32.5MW.


187 Power into Stillwater Mine is reticulated from the West Substation through three incoming lines. Incoming line #1 distributes to the following:  Upper West Feeder;  5000 West Portal Feeder;  West Compressor/Surface Feeder;  Vertical Mill; and  Skip Hoist and Shaft feeder. Incoming Line #2 feeds to the following:  Main Shaft Feeder A for mining operations;  Main Shaft Feeder B for mining operations;  Man hoist;  Concentrator 480V loads;  WFVR fans; and  Auxiliary services including workshops and hoist room. Incoming line #3 feeds the following:  Ball and Sag mill;  480v transformer #1; and  480v Transformer #2. Stillwater Mine has a 750kVA emergency generator to power the cage hoist and provide emergency power for the phones and other small critical loads. All underground transformers are dry-cooled, eliminating the risk of oil leakage and/or fire. In addition, these transformers are skid mounted, installed in concreted cubbies, well- demarcated and supplied with lighting. Stillwater Mine has a detailed inventory of all underground switchgear, controller and transformers managed through the JD Edwards Management System. Bulk Water 15.1.5.1 Water Supply The bulk water supply for the Stillwater Mine is a mix of fresh make-up water from supply wells and recycled mine water. The overall water balance is positive meaning that water disposal is required. Treatment and disposal of surplus water are discussed in Section 15.1.5.2. The onsite water supply wells provide potable water for the mine, make-up water for reagent mixing, and cooling water to some systems (e.g., lube system cooling). Onsite, the water is reticulated to various sites through a network of pipelines (distribution system). The two existing wells and associated distribution system is adequate for the Stillwater Mine ramp up production requirements. Water consumption from the wells is approximately 110gal per minute. The Qualified Person recognises that the net positive water balance at the site is adequate for ongoing operations. 188 15.1.5.2 Water Treatment The water treatment system at Stillwater Mine treats and disposes impacted water from the underground mining operations. Impacted mine water is first clarified before a portion is reused as mine service water while the remaining water continues to the biological treatment process to remove nitrates and is then disposed of by land application or infiltration. The current system is designed to treat and disposal of 2 500gal per minute. Current actual water treatment flowrates are approximately 600 gal per minute from the Stillwater West Section and 900 gal per minute from the Stillwater East Section (total of 1 500 gal per minute) which is approximately 60% of design flow. The Stillwater West Section is expected to remain near 600gal per minute for the foreseeable future. Results of groundwater studies in FY2021 suggested water inflows into the Stillwater East Section exceeding 3 000gal per minute, an estimate that has since been derated to 1 600gal per minute informed by results of subsequent review work completed in FY2021. Therefore, water treatment projections could increase to 2 200gal per minute, which remains below the current treatment plant and disposal capacity of 2 500 gal per minute. Nonetheless, efforts are underway to complete evaluation, engineering, and permitting in the future an expansion is needed in the future. In addition, clarifier upgrades were completed in FY2021 to increase capacity to 2 500gal per minute for each clarifier resulting in a total clarifier capacity of 5 000gal per minute. 15.1.5.3 Septic System The sanitary utilities at the Stillwater Mine consist of a septic system that includes a solids tank, an Advantex treatment system and a leach field. The system is operated primarily as a treatment and disposal system with the leach field providing secondary or back-up disposal. The treated effluent is sent to the Hertzler Land Application Disposal system for disposal. The capacity of the septic system of 18 000gal per day is adequate for the steady-state requirements for Stillwater Mine. Roads Stillwater Mine is located approximately 30 miles southwest of Absarokee and 4 miles south-southwest of Nye. It is accessed from Absarokee by the mainly unpaved County Road 420, which passes the Hertzler Ranch TSF or via the paved State Highway 78 and State Highway 419 and Nye Road. The road network on the Stillwater Mine site consists of unpaved roads, which are primarily used for the transport of logistics and stores for the functioning of the mine and for transport of personnel for access to the infrastructure positioned around the mine site. Equipment Maintenance Stillwater Mine has three workshops on surface, which are the following:  Surface Locomotive Workshop: This has a single bay service and mechanical repair facility for all rolling stock (locomotives and ore cars) operating on the 5000 Level West. This workshop is primarily for work on wheels and engines; 189  East Side Workshop: This has multiple bay service and mechanical repairs facilities serving surface equipment as well as major repairs and rebuilds of primary equipment from the East Side.  Stillwater West Workshop: This has multiple bay service and mechanical repair facilities for light and medium duty underground equipment as well as major repair/rebuild services for primary underground gear equipment that can be moved to the surface. It has full machining, welding, and Diesel Particulate Matter testing capabilities. In addition, Stillwater Mine has the following underground workshops:  6100W Level Workshop: This has multiple bay services and mechanical repair shop;  5600E Level Workshop: This has multiple bay services and mechanical repair shop for all rubber- tired equipment in the Stillwater East Section of the mine;  5000W Level Workshop: This is dedicated to the trackless equipment, which is serviced in the mine. It has a single bay service facility and is available for light mechanical repairs, servicing and electrical repairs on mobile equipment. All the rail equipment on this level is serviced and repaired on surface;  3500W Level Kiruna Workshop: This is a single bay service and mechanical repair workshop facility, which was designed specifically for the maintenance of the three Kiruna trucks and for maintenance of the AD30 Cat Trucks. The Kiruna trucks have been decommissioned;  3500W Level Locomotive Workshop: The 3 500 Level is primarily an ore and waste rock tramming level. Therefore, the workshop is a two-bay service and repair facility for rolling stock;  3800W Level Workshop: This is a two-bay service and mechanical repairs shop for all production equipment in the FWL;  3800E Level Workshop. This is a multiple bay service and mechanical repair shop subject to the same requirements at the 3800W Level Workshop;  2000W Level Workshop: This is the workshop on the lowest level, which caters for mechanical, electrical and general repair and services in multiple bays. All the underground workshops are well-equipped with good lighting, clean concrete floor areas for maintenance and wash bays to ensure quality inspections and are stocked with the appropriate tools and lifting equipment. Some of the workshops also provide for an administrative office underground to ensure that the planned maintenance system is updated timeously. A well-developed maintenance programme based on the JD Edwards Planned Maintenance system is in place and this includes daily, weekly and monthly scheduled maintenance. Major rebuilds of equipment take place on site or are sent to offsite Original Equipment Manufacturer (OEM) repair shops. In addition, the Sibanye-Stillwater US PGM Operations are developing a robust Asset Management Plan. Pre-use checks for all equipment are carried out and logged by the machine operator. Each piece of equipment has a unit number, which is entered into the management system. Equipment performance is logged daily by the operator onto the log sheet, which is uploaded into the system. The maintenance schedule flags equipment for weekly or monthly maintenance. The planned maintenance system records all equipment on the system for availability, utilisation, unit cost, age and planned replacement per the policy for that classification. Job cards are uploaded into the system to ensure each unit has a history of replacements done. The mine keeps over 500 maintenance items on the system. Shop Availability Maps are used by the mine to assist in planning and updating the status of work in the underground workshops. The overall physical map, including all workshops, is updated by the Workshop 190 Foreman daily to ensure that production teams know the status of repairs/maintenance on the equipment. The Maintenance Department has a target of 80% availability for its major mobile equipment. This percentage is an acceptable standard in industry for underground production and development fleets, although higher availabilities have been achieved at other mines. The unit utilisation is generally lower than industry norms due to the geographical spread of the mining operations. In addition, Stillwater Mine has found it more cost effective to provide more equipment than available at other mines (particularly the equipment that is not readily mobile such as bolters and drill rigs) to save on transport between the geographically spread underground production workings. Buildings Several new or modified buildings are required to support the production ramp up at Stillwater Mine. The following buildings were included in the expansion or modification plan:  Expansions: warehouse, core shed and offices to support additional personnel; and  Modifications: dry-house. Significant expansion of the warehouse at Stillwater Mine (7 500 square feet), implemented in 2019, was needed to accommodate the additional mine and concentrator consumables. The dry-house, relocated ambulance/rescue facility and expanded foreman offices are included in the North Multi-Service Wing. This Multi-Service Wing expansion was completed in FY2021, and includes:  Seven new beat rooms;  Renovated dispatch area with a “high-tech” control room;  Two-bay ambulance garage;  Medical area;  Mine rescue area; and  Five offices for foremen. The core shed handles all drillcore from the drilling and ore control related to the mine development and mine operations. The production ramp up approximately doubled the volume of core requiring handling and logging. The core handling area was consequently expanded within the existing structure to add 1 400 square feet, which displaced the ambulance, paramedic and rescue area. The core shed expansion was also completed in late FY2021. A geology and engineering office expansion was also completed, and this supports the additional Engineers and Geologists needed for the expanded operations. Figure 78 shows the overall site layout for Stillwater Mine.


191 Figure 78: Stillwater Mine Site Layout Transportation Personnel transportation to the Stillwater Mine is a combination of company supplied bussing and light vehicles, and personal vehicles. Transportation of salaried personnel is primarily by company owned light vehicles. Based on the current light vehicle to salaried personnel ratio, no additional light vehicles will be required for future mine plans. Hourly personnel travel to and from site either by company bussing or personal carpools. With employment growth and traffic commitments, additional busing is anticipated for the future mine plans. 192 East Boulder Mine Complex Concentrator Infrastructure The processing plant infrastructure at East Boulder Mine was built in 1999. The plant infrastructure is in a good condition, with the plant having been operated below nameplate capacity since establishment. Appropriate sustaining capital budget provisions have allowed for the undertaking of routine planned maintenance according to the JD Edwards Maintenance Control system. The power supply to the concentrator plants is described in Section 15.2.3. Tailings Storage Facilities The TSF at the East Boulder Mine comprises two cells of a single slimes impoundment as the current primary storage. Stage 1, comprising Cell 1, was operated from 2001 to 2007 after which Cell 2 became the primary deposition facility (Stage 2). Stage 3 is an embankment lift of Stages 1 and 2 and was operated from 2014 through 2020. Stage 4 is currently being filled and has been operated from FY2020. Stage 5 is an additional embankment lift and become active in FY2024. Beyond Stage 5, the East Boulder TSF has one additional embankment lift permitted and approved – i.e. Stage 6. Concentrator tailings are sampled and pumped to the underground sand plant where it is classified into coarse sand and slimes fractions. The sand remains underground and is pumped into stopes for backfilling purposes, whilst the slimes fraction is pumped back to surface. The slime is then pumped via one ten-inch pipeline to the TSF for deposition. Deposition on the TSF is via periodic rotational discharge of tailings slurry around the perimeter of the facility using a group of spigots. Once a localised tailings beach has formed, deposition is transferred to another group of spigots at a different location. Water reclamation is achieved via three inclined reclaim pumps and pipelines located on the south- western embankment of the TSF, closest to the concentrator, which discharges into the reclaim water tanks at the concentrator. All stages of the TSF are geomembrane lined. Basin underdrain and seepage measurement is performed and monitored via vibrating wire piezometers whereas embankment crest-mounted survey monuments are used to measure slope slippage or movement. Additional inclinometers are installed around the base of the impoundment to monitor deeper ground movement and displacement. The basin underdrain pore pressures are monitored on a weekly basis via the piezometers, and these respond quickly to changes in the basin underdrain pumping rate. Water drainage results in changes in the tailings mass consolidation and hence maximises storage availability and assists in long-term closure planning. The concentrator performs weekly, monthly and quarterly TSF inspections and monitoring per its standard procedures which are reviewed as part of the annual Engineer of Record inspection of the TSF performed by Knight-Piésold. The most recent inspection was performed in September 2023, with a review period from October 2022 to September 2023. No material issues were identified, but a corrective action plan for the issues which were identified has been developed and planned to be submitted to the MDEQ by 9 January 2024 as required and in compliance with the MCA. 193 Filling of Stage 4 is currently underway and projected to continue into FY2024 with the freeboard allowance provided with completion of lining for Stage 5. As part of the annual inspection of the East Boulder TSF, Knight-Piésold calculated a projected fill rate of the current and planned TSF capacity as an elevation above mean sea level by year. Stage 5 and Stage 6 lifts are already permitted with Stage 5 construction completed and Stage 6 under construction. The embankment crest maximum elevation of Stage 5 has been designed by Knight-Piésold as 6 330ftmamsl, and the Stage 6 crest has been designed at 6 344ftmamsl. Water treatment facilities were upgraded to increase the water treatment capacity and the Guard Shack was also relocated to allow for the Stage 6 build. Based on Knight-Piésold’s current filling calculations, the Stage 4 limit is estimated to be reached in Q3 2024. As part of the planning to meet the Inflow Design Flood management procedures, an interim overflow channel will be installed, which will extend the capacity as indicated in Figure 79, while the Stage 5 construction is scheduled to be complete in January 2024, well ahead of the required first discharge. The Qualified Person considers the design and capacity filling calculations for the TSF to be appropriate and to take cognisance of the planned production. Figure 79: East Boulder TSF Calculated Elevation Profile 194 The Stage 5 and Stage 6 lifts are currently under construction, with Stage 5 scheduled for completion and lining in Q FY2024 and Stage 6 scheduled for completion in FY2025. The Stage 5 and Stage 6 foundation preparation and infrastructure relocation were completed in late FY2023. This work included relocation of soil piles, fencing, underdrain collection basin, nitrogen collection pond, recycle pond and Pumphouse 1, main overhead powerline, mill overhead powerline, guard shack and gate, transformers, fiber, Boe Ranch pipeline and vaults, underdrain pipeline, nitrogen pond pipeline, groundwater well pumpback system, inclinometers, warehouse septic system, surface electrical building, fire hydrants, wash bay, burn pit, laydown yard, equipment ready line, mill fuel storage, and mine access road. The Qualified Person notes Knight-Piésold’s current filling calculations discussed above and that the TSF basin filling schedule depends on the incremental addition of settled tailings solids and on changes in the supernatant pond volume. The TSF filling curve has been updated with the estimated tailings disposal projections provided by Sibanye-Stillwater and an assumed constant supernatant pond volume. An updated short-term filling curve as of September 2023 is shown on Figure 80 and briefly summarised as follows:  The water level was at approximate elevation 6 311.4ft;  The supernatant pond volume was approximately 199Mgal;  The Stage 4 TSF (maximum filling level elevation 6 315 ft) and Stage 5 TSF (maximum filling level elevation 6 324ft) will be reached in September of 2024 and December of 2027, respectively, assuming 55% of the tailings are deposited to the TSF, the existing water pond volume is maintained and the settled dry tailings density is 70lb/ft3; and  Stage 6 is currently projected to reach capacity in December 2032. Basin underdrain water is transferred to the mine water recycle pond. As illustrated in Figure 80, the rate and timing of impoundment filling depends on changes to the supernatant pond volume as well as the proportion of the total tailings that are ‘stored’ as underground backfill. Sibanye-Stillwater’s tailings deposition records indicate that approximately 54% of the tailings solids were deposited into the TSF from January through September 2023, with the remainder of the tailings solids stored as underground backfill. Assuming that the plant production remains approximately consistent with previous years, then about 50% to 55% of the total tailings solids will continue to be deposited into the TSF. Furthermore, if the 200Mgal supernatant pond volume is also maintained, then the Stage 4 TSF would reach capacity in September 2024 (with 6ft. freeboard allowance maintained). Detailed pond level and volume monitoring must continue on an ongoing basis. Figure 79


195 Figure 80: East Boulder TSF Calculated Elevation Profile The capital budget for East Boulder Mine includes capital expenditure for the Lewis Gulch TSF comprising $5.5 million for infrastructure and topsoil relation in FY2026 and $53.4 million for construction between FY2027 and FY2028, and $7.5 million for closure between FY2043 and FY2045. The budget includes costs for a future TSF amounting to $100 million between FY2039 and FY2042. The Qualified Person is satisfied with the capital allowance for new TSFs (e.g., Lewis Gulch TSF and another future TSF) that will be required in future. Dry Fork Waste Rock Storage Area In conjunction with the construction of new and expanded tailings facilities, a new waste rock storage area has been designed. The proposed Dry Fork Waste Rock Storage Area (West Storage Area) was included in the permitting of the Lewis Gulch TSF within Amendment 004. Approval of Amendment 004 is expected in July 2024. The Dry Fork Waste Rock Storage Area (West Storage Area) will be 102 acres in size and is designed to contain 5.4 million cubic yards of material. Based on current mine plans, this will provide waste rock storage up to FY2047. A second, separate waste dump (East Waste Rock Storage Area) has been envisioned in the Dry Fork Waste Rock Storage Area with some preliminary design work 196 completed. The East Waste Storage Area in the Dry Fork Waste Rock Storage Area will provide an additional 28 years of storage beyond FY2047 (up to FY2075). Permitting of the East Waste Storage Area is anticipated in the 2040s. Construction of the Stage 6 TSF lift is scheduled for completion in January 2026. Upon completion of the Stage 6 TSF embankment lift and lining, waste rock will need to be placed in the Dry Fork Waste Rock Storage Area or within the existing Stage 6 TSF. Construction of Phase 1 of the Dry Fork Waste Rock Storage Area is scheduled for to begin in late FY2024 and continues to FY2025 based on anticipated regulatory approval which will be permitted as part of the Lewis Gulch TSF. A bridge and access road will be constructed at the start of Phase 1 in FY2025. The capital budget for the Phase 1 of Dry Fork Waste Rock Storage Area (construction and lining) amounts to $28.5 million over the period FY2024 and FY2026. Phase 2 to Phase 4 also have capital provisions in the capital budget for East Boulder Mine in FY2030 ($2.9 million), FY2035 ($7.5 million) and FY2046 ($6.3 million), respectively, as well as for closure between FY2055 and FY2056 ($5.5 million). The Qualified Person is satisfied with the capital provisions for construction and closure of the waste rock storage facilities. Power Power to East Boulder Mine is fed from the North West Energy’s 161kV powerline via a tap located north of Springdale and then via the Duck Creek Substation. Park Electric, a power co-operative, supplies power to the mine site and owns the distribution facilities. The power feed from Duck Creek to McLeod and from McLeod to the mine is via a 69kV powerline. Sibanye-Stillwater owns two main substations situated at East Boulder Mine. The mill transformer is a 15/20MVA 69kV to 4 160V and the mine operations transformer is a 10/14MVA 69kV to 13.8kV. There are no spares for either transformer, but there is a cross feed between the two substations which is rated for 8MW. Dedicated capacity for East Boulder Mine is 23MW at a unity power factor contracted from Park Electric, which is adequate for the increased production levels associated with the Fill the Mill Project. East Boulder power loads are currently as follows:  Mine and surface: 7MW at a 0.91 power factor (approximately 77% of maximum capacity);  Concentrator: 5.5MW at a 0.93 power factor (approximately 40% of maximum capacity); and  Monthly Maximum Peak: 12.5MW at a 0.91 power factor. There are two main feeders that feed the underground switchgear from the surface switchgear. Normal operation is to use one feeder and have the other feeder available as a backup. One feeder is installed in Tunnel #1 and the second feeder installed in Tunnel #2. Current underground load is approximately 5MW at a 0.80 power factor. Each of these feeder cables have a loading capacity of approximately 7MW (assuming a 5% maximum voltage drop). East Boulder Mine has two 2MVA Caterpillar 3516B diesel generators which were installed in 2001 at the portal on surface. These generators are currently permitted only as emergency generators, which should be operated for at most 500 hours per year. The generators are designed to operate at the same time 197 in parallel and share the load. When running in parallel, the continuous load on these generators is limited to 3.5MW to allow for peak demands of less than 4MW. Bulk Water 15.2.5.1 Water Supply The water supply for the East Boulder Mine is a mix of fresh make-up water from groundwater supply wells, recycled water from the water treatment facilities and ground water encountered during mining operations. The overall water balance is positive, and disposal of surplus water is required. The groundwater supply wells include the potable water system which provides potable water to the surface operations only and the freshwater system which provides fire water for surface operations and reagent make-up water for the mill. Onsite, the water is reticulated to various sites through a network of pipelines (distribution system). Water consumption from the wells is approximately 50gal per minute and is not expected to increase significantly in future. Water Right Permits allow for beneficial use of up to 262gal per minute from mine water and up to 200gal per minute from potable wells. Treatment and discharge to percolation is not considered a beneficial use and discharge through the Montana Pollutant Discharge Elimination System permit is not included in the water right quota. Current water rights, therefore, are sufficient to support the mine plan. 15.2.5.2 Water Treatment The water treatment system at East Boulder Mine treats and discharges mine water from the underground mining operations. The current system was designed to treat approximately 750gal per minute of water from the underground mining operations. Mine water is first clarified, with a portion recycled to the underground drill water reservoir while the remaining water continues to the biological water treatment process to remove nitrates and ammonia. Treated water is split between recycling for mine use and disposal by percolation to groundwater, based on operational demands. In late FY2015, East Boulder Mine received a new Montana Pollutant Discharge Elimination System (Water Discharge) permit, which stipulated stringent metals discharge limits. The permit allows for a five- year interim period for treatment system evaluation and improvements before the new discharge limits apply. A new discharge permit was issued in September 2023 which included a revision to the discharge limits. For compliance, the drilling of a deep injection test well was undertaken and successfully tested. The testing of an existing 45 000ft pipeline from East Boulder Mine site to the injection well system was also completed and commissioned in FY2020. This pipeline was designed to carry treated mine water effluent to an injection well at the Yates Gravel Pit for compliance with the discharge limits. 15.2.5.3 Septic System The East Boulder Mine wastewater treatment facility was originally designed and permitted in 1998. The system serves the upper bench office buildings and the concentrator. The design basis for the original system was 600 employees with a peak per capita flow rate of 15gal per day (i.e., 9 000gal per day for the whole mine). The system consisted of approximately 700ft of 8-inch diameter PVC gravity sewer, 198 combined septic dose tank, and two zone conventional drain field with each zone having thirteen 100ft long laterals. In 2006, the collection system was expanded to include a Mobile Dry Building which was included in the original design of 600 employees. The 2006 improvements also made modifications to the existing drainfield to correct ongoing maintenance issues. The 2006 drainfield modifications consisted of replacing the existing conventional drain field with trench infiltrator chambers, adding one lateral to each zone of the drainfield for a total of twenty-eight 100ft long laterals, updating dose pumps and controls, and reducing the drainfield application rate from 1.2gal per day/ft2 to 0.8gal per day/ft2 (due to updated regulations). In FY2015, measured flow tests resulted in an approximate daily flow rate of 9 000gal per day with peak daily flows of 11 000gal per day. Permitting to accommodate the increase is complete as well as the upgrade of the existing wastewater treatment system to 11 000gal per day. The improvements have increased the septic and dose tank capacity and controls. Roads East Boulder Mine is located approximately 25 miles south of Big Timber. The mine is accessed from Big Timber via the paved State Highway 298 and the unpaved East Boulder Road maintained by Sibanye- Stillwater. The road network on the East Boulder Mine site consists of unpaved roads which are primarily used for the transport of logistics and stores for the functioning of the mine and for transport of personnel for access to the infrastructure positioned around the mine site. Buildings East Boulder Mine has adequate modern, fit for purpose offices for administration, technical and personnel services. The mine also has a change house in proximity for the use of mine staff as well as drill core processing and storage facilities. The processing plant has an additional separate small control office facility for operational staff. Likewise, the surface engineering workshops have small operational offices within the workshops. The mine provides adequate secure parking in a gravel parking area adjacent to the main office entry. The mine complex is fenced, with the complex accessed from a security guard manned main gate. Figure 81 shows the overall site layout for East Boulder Mine.


199 Figure 81: East Boulder Mine Site Layout Equipment Maintenance East Boulder Mine also makes use of the JD Edwards Planned Maintenance system, with the robust Asset Management Plan. The mine has two workshops on surface, which are the following:  Surface Locomotive Workshop: This has a single bay service and mechanical repairs facility for all rolling stock, and includes facilities for work on wheels and engines on the locomotives and ore cars; and 200  Surface Engineering Workshop: This has multiple bay service and mechanical repair facilities for surface trucks with full machining, welding and electrical maintenance facilities. The mine has the following workshops underground:  6500 Level Workshop: This has multiple-bay facilities and carries out repairs for both mechanical and electrical faults and maintenance. It also provides a service facility for the rail bound equipment and the adjacent sandfill plant. The workshop is equipped with separate wash bay, office area, warehouse and fuel store. Major overhauls are carried out in the surface workshops;  A small service bay at 68 780 Level.  7900 Level Mobile Workshop: This is primarily for the mobile equipment in the upper mine. It has an ambulance and medical support centre and adjacent refuge bay. This is expected to be a permanent workshop for the life of the mine. All the underground workshops are well-equipped with good lighting, clean concrete floor areas for maintenance, wash bays to ensure quality inspections, and are stocked with the appropriate tools and lifting equipment. Transportation Personnel transportation to East Boulder Mine is a combination of company supplied bussing and company supplied light vehicles. Current company policy mandates the use of company supplied bussing for hourly personnel. Transportation of salaried personnel is primarily by company owned light vehicles. Based on the current light vehicle to salaried personnel ratio, no additional light vehicles will be required for future mine plans. Columbus Metallurgical Facility The Columbus Metallurgical Complex, which houses the smelter, base metal refinery, laboratory and recycling plant, was built on freehold owned by Sibanye-Stillwater. The building and stack heights are limited due to the proximity of the light aircraft field. The facilities are secured by fencing and access is limited to card holding employees. The Columbus Metallurgical Complex includes well-established automated sampling and sample processing facilities with a robotic operated sample laboratory. Office facilities are adequate for the required staff to operate the base metal refinery and smelter. Infrastructure at the Columbus Metallurgical Complex is maintained in a good operational condition through adequate capital provisions for maintenance and upgrades as required. Power supply to these facilities is from North West Energy at the standard 100kV at the main switch station and two-step down transformers. Sibanye-Stillwater keeps a spare transformer onsite and, therefore, power supply is reliable. 201 MARKET STUDIES Introduction PGMs (also referred to as Platinum Group Elements or PGEs) comprise platinum, palladium, rhodium, ruthenium, iridium and osmium. The Bushveld Complex in South Africa contains approximately 80% of the known global PGM mineralisation and produces approximately 80% of the world’s annual PGM supply from the UG2 and Merensky Reefs. The J-M Reef mined at Stillwater and East Boulder Mines is the sole source of primary palladium and platinum production in the USA, accounting for approximately 5% of the world annual primary PGM supply. PGM mineralisation in the J-M Reef is dominated by palladium and platinum, with other PGMs occurring in negligible quantities. Sibanye-Stillwater commissioned an independent PGM market study by its research company, SFA Analytics (SFA Oxford), which was completed in October 2023. Information from this source along with negotiated contracts inform Sibanye-Stillwater’s price and sales predictions. Given that palladium and platinum account for almost 100% of the revenue generated at Stillwater and East Boulder Mines, this market review focuses on these two metals. PGM Market Overview According to SFA Oxford, both platinum and palladium markets were in supply deficit during 2023 because of continued light vehicle demand recovery from both pandemic lows and the semiconductor chip shortage, as well as periods of supply disruption in South Africa and Russia. However, palladium prices declined 38% from $1 725/oz at the beginning of 2023 while the platinum price was rangebound, averaging $904/oz over the year. In palladium’s case, this is interpreted to be because of increasing sales of Russian palladium to China through 2023, eroding price support for palladium. The relatively stable platinum price belied the decline in PGM basket prices for South African producers through 2023. Global light vehicle production amounted to 82 million units in 2023, with production forecasts for 2024 anticipated to exceed the 2019 (pre-COVID-19 pandemic) level of approximately 86.5 million units. The main regions driving this production outlook are China, Japan, India and Korea. Through 2023, the US automotive sector faced disruptive strikes with concurrent inflation and high interest rates tempering light vehicle sales. The Battery Electric Vehicle (BEV) share of global light duty vehicles grew from 9% in 2022 to 12% in 2023. However, cautious BEV uptake in the West and aggressive price cuts have seen a number of European and US automakers scaling back prior BEV sales targets and timelines. The forthcoming elections in Europe and the US in 2024 may also contribute to a slower pace of electrification growth in these jurisdictions. 202 Platinum and Palladium Demand and Supply Demand Drivers According to SFA Oxford, the main uses of platinum are as a catalyst for automotive emissions control, in a wide range of jewellery pieces and in industrial catalytic and fabrication applications. Palladium is primarily used as a catalyst in the automotive sector, mainly in gasoline-powered on-road vehicles, but alongside platinum in parts of the light-duty diesel engine after-treatment too. The second main use of palladium is in electrical components, specifically in multi-layer ceramic capacitors (MLCCs), as conductive pastes and in electrical plating. Platinum Through 2023, the platinum price oscillated in a narrow range between $1 080/oz and $904/oz, settling at $970/oz at the beginning of 2024. In 2023, global primary platinum supply is estimated to have grown by 1.4% year-on-year (y-o-y) to 5.56Moz, with production increases in South Africa, Zimbabwe and the North Americas offsetting a 1.2% (-8koz) y-o-y reduction in Russian production because of smelter maintenance at Nornickel. Through 2023, prolonged Eskom load curtailment in South Africa slowed the processing of an estimated 90koz of platinum contained in excess Work-in-Progress (WIP) stocks. Global primary platinum supply remains 8.8% (-538koz) lower than 2019’s pre-COVID 19 pandemic production levels. Autocatalyst recycling provides the bulk of secondary PGM supply and contributed 1.4Moz of platinum in 2023, in line with 2022 recycling levels. According to SFA Oxford, platinum demand for all applications is projected to rise by 1% in 2024 to 7.7Moz, supported by growth in light vehicle production, which is recovering from the semiconductor chip shortage, and expanding use of platinum loaded gasoline autocatalysts. This autocatalyst demand accounted for some 3.5Moz or 44% of platinum demand in 2023 and is expected to continue at this level in 2024. Chemical, electrical, glass and medical demand for platinum is forecast to continue to rise steadily from 2023 demand levels of 1.7Moz. Through 2024, jewellery demand for platinum is expected to remain stable at or near 2023 levels (1.47Moz). Platinum is required across the entire hydrogen value chain, including the upstream, mid-stream and downstream segments, and demand is predicted to rise from current levels of approximately 190koz per annum to some 365koz per annum by 2030. The hydrogen economy and industrial applications are therefore the long-term growth areas for platinum demand. The platinum market’s supply deficit of 450koz at the end of 2023 is forecast to continue through 2024 to a level of approximately 445koz by the end of the year. Palladium Palladium prices declined from $1 725/oz at the beginning of 2023 to $1 075/oz at the beginning of 2024. Global primary palladium supply reduced by 1.7% y-o-y in 2023 to 6.34Moz, with production increases in South Africa, Zimbabwe and the North Americas being eclipsed by reduced Russian production because of lower efficiencies related to alternative equipment sourcing (a consequence of the Russia- Ukraine conflict) and a period of smelter maintenance.


203 Global primary palladium supply in 2023 was 11.6% lower (-836koz) than pre-COVID 19 pandemic production levels in 2019, with Zimbabwe being the only jurisdiction to display growth since 2019 following the completion of the third concentrator at Ngezi Mine. Primary palladium supply is forecast to increase 2.2% y-o-y in 2024, to approximately 6.42Moz, with higher palladium yields anticipated from mines in South Africa and the North Americas. Over the next decade, secondary palladium supply from autocatalyst recycling is anticipated to grow from the 2023 level of 2.4Moz as the stock of aging light vehicles to be scrapped will progressively yield higher PGM loaded autocatalyst. 2023 is interpreted by SFA Oxford to have been a peak of all-application global palladium demand at 10.2Moz. Price-driven substitution for platinum in autocatalyst applications is anticipated to dampen 2024 demand to below 8.0Moz from the 2023 palladium-for-autocatalyst peak of 8.2Moz. Anticipated demand for palladium in all other applications, except for dental uses, is forecast to remain steady through 2024 at current levels of approximately 1.95Moz per annum. Dental use demand for palladium is forecast to continue to gradually decline from present levels of approximately 170koz per annum because of price driven substitution into alternative materials. Palladium demand related to the hydrogen economy is restricted to the mid-stream and downstream segments including catalysts for methanol synthesis, and for sustainable aviation fuel and diesel manufacture. Some additional demand for palladium over the next decade will depend on the pace of development of these hydrogen economy segments. SFA Oxford anticipate that the 2023 palladium supply deficit of 1.49Moz will be reduced to a supply deficit of approximately 855koz in 2024. Palladium and Platinum Pricing Outlook For business planning and Mineral Reserve estimation, Sibanye-Stillwater uses forward looking prices that it considers will stay stable for at least three to five years, and will significantly change if there is a fundamental, perceived long-term shift in the market, as opposed to basing it only on short term analyst consensus forecasts. Sibanye-Stillwater also considers its general view of the market, the relative position of its operations on the costs curve, as well as its operational and company strategy in its forecasting of forward-looking prices. On a monthly basis, Sibanye-Stillwater also receives an independent report from UBS Bank (Commodity Consensus Forecasts Report) which contains consensus outlooks from the various banks on a broad range of commodities. It benchmarks its forward-looking prices to the market consensus forecast. Table 48 summarises the forward-looking prices of palladium and platinum applied by Sibanye-Stillwater for business planning and Mineral Reserve declaration as at December 31, 2023. This also shows comparison between Sibanye-Stillwater and Market Consensus forward-looking prices. The Qualified 204 Persons note that the comparison shows overall agreement between the price forecasts and, therefore, Sibanye-Stillwater forward-looking prices are reasonable. Table 48: Comparison of Sibanye-Stillwater and Market Consensus Prices Metal Unit Market Consensus Forward Price – 2024 Mineral Reserve Price – 2024 Platinum USD/oz 1 135 1 250 Palladium USD/oz 1 213 1 250 Material Metals Marketing Agreements The Columbus Metallurgical Complex and Precious Metal Refining Sibanye-Stillwater’s wholly owned Columbus Metallurgical Complex is a state-of-the-art operation that provides smelting and refining processes for PGM concentrates from the Stillwater and East Boulder mines. In addition, the complex facilitates recycling operations for various materials containing PGMs, principally automotive catalytic converters that are provided by third-party suppliers under arms-length commercial offtake or toll treating contract terms. The complex produces a PGM-rich concentrate after base metal refining that is shipped to a third-party precious metal refinery under a toll processing agreement that provides Sibanye-Stillwater returns of finished metal. Sibanye-Stillwater utilises a single third-party company for all of its precious metals refining services for Sibanye-Stillwater’s US PGM Operations. All of Sibanye-Stillwater’s current mined palladium and platinum in the United States is committed for sale to such company. The refining and sales agreements are multiple year contracts entered into with the third-party company. Sibanye-Stillwater pays its refiner a per-ounce refining charge for toll processing of the refined PGM-rich concentrate, and the refiner also retains a small percentage of contained metals. Refined PGMs of minimum 99.5% purity in sponge form are transferred upon sale from Sibanye-Stillwater’s account to the account of the third-party refiner. The refiner will purchase all of the mined palladium and platinum at competitive prices based on a pricing mechanism linked to various agreed to industry benchmarks. Wheaton International Streaming Agreement In 2018, Wheaton Precious Metals International Limited (Wheaton International) and the Group entered into a Streaming Agreement. As per the Streaming Agreement, 100% of refined mined gold and 4.5% of refined mined palladium from the Stillwater Mining Company operations (Sibanye-Stillwater US PGM Operations) will be delivered to Wheaton International over the life of mine of the operations. Each ounce is identified as a separate performance obligation. In exchange for this, Wheaton International paid the Sibanye-Stillwater US$500 million on 25 July 2018 (the Advance Amount). Under the Streaming Agreement, in addition to the Advance Amount, Wheaton International will pay Sibanye-Stillwater 18% of the US dollar spot palladium and gold prices for each ounce delivered under the Streaming Agreement until the Advance Amount has been reduced to nil through metal deliveries. Thereafter, Sibanye-Stillwater will receive 22% of the spot US dollar palladium and gold prices for each ounce of palladium and gold delivered under the Streaming 205 Agreement. The contract will be settled by the Sibanye-Stillwater delivering metal credits to Wheaton International representing underlying refined, mined gold and palladium. As per the Streaming Agreement, the following entitlements apply:  Palladium entitlement percentage: o The palladium entitlement percentage will be either 4.5%, 2.25% or 1% over the life of mine, depending on whether or not the Advance Amount has been fully reduced, and a certain number of contractual ounces have been delivered (375 000oz for the first trigger drop down to 2.25% and 550 000oz for the second trigger drop down rate to 1%).  Gold entitlement percentage: o The gold entitlement percentage will be 100% over the life of the mine;  Monthly cash percentage: o The monthly cash payment to be received is 18%, 16%, 14% or 10% of the market price of the metal credit delivery to Wheaton International while the Advance Amount is not fully reduced. After the Advance Amount has been fully reduced, the cash percentage is 22%, 20%, 18% or 14%. In both cases, the payments by Wheaton International may be reduced if debt covenants exceed three and half multiples of the net debt to adjusted Earnings Before Interest, Taxes, Depreciation and Amortisation (EBITDA) ratio. The balance of the ounces in the monthly delivery (i.e. 100%-18%= 82%) is then used to determine the utilisation of the deferred revenue balance. Sibanye-Stillwater agreed to use commercially reasonable efforts to facilitate the development of the Blitz Project. The Streaming Agreement includes a completion test on the development of the Blitz Project, including completion of underground development, critical surface infrastructure and expansion of the concentrator production output. If Sibanye-Stillwater fails to meet certain completion targets in relation to the Blitz Project, it is required to pay Wheaton International certain cash amounts. The Qualified Person notes that, with the achievement of the agreed to project milestones, the completion test on the development of the Blitz Project has been scheduled for completion during the first half of 2024. The Streaming Agreement, with an effective date of 1 July 2018, continues for an initial period of 40 years and can be extended for successive 10-year periods until termination notice is given or there are no active mining operations at the Sibanye-Stillwater US PGM Operations. The Qualified Persons note that the Streaming Agreement is material to the Sibanye-Stillwater US PGM Operations but sets out conditions that are not excessively onerous and can easily be achieved by Sibanye-Stillwater if the current LoM plans for Stillwater and East Boulder Mines are executed as planned. 206 ENVIRONMENTAL STUDIES, PERMITTING, PLANS, NEGOTIATIONS/AGREEMENTS Social and Community Agreements In order to assist in managing Sibanye-Stillwater’s Social Licence to Operate, a progressive and effective Good Neighbor Agreement was signed in 2000 and this agreement was amended in 2005, 2009, 2015 and 2023. The Good Neighbor Agreement is a legally binding contract between Sibanye-Stillwater, the Northern Plains Resource Council, Cottonwood Resource Council and Stillwater Protective Association, which is binding on current and future owners and managers of the Stillwater and East Boulder Mines. It provides an avenue for the citizen groups to access information on the Stillwater and East Boulder Mines and to participate in decisions on the operations that may impact the local communities, economies, or environment. In essence, it provides for citizen oversight of Stillwater and East Boulder Mines to guarantee protection of the area’s quality of life and productive agricultural land and allows for local communities to have access to critical information about mining operations and the opportunity to address potential problems before they occur. Furthermore, it requires the information to be sufficiently detailed to permit assessment of potential environmental and social impacts. There are no commitments to local procurement and hiring in the Good Neighbor Agreement. While not contractually obliged to commit to local procurement and hiring, Sibanye-Stillwater gives preference to local skilled personnel as deliberate local economic empowerment. Both Stillwater and East Boulder Mines have a Good Neighbor Oversight Committee that meets three times per year. In addition to these formal, transcribed meetings, a Technology Committee and other committees meet as needed but communicate weekly to address ongoing projects. This constant stakeholder engagement enables citizens to meaningfully engage in the permitting and mine planning processes and provide feedback in advance of formal comment periods. This approach allows Sibanye-Stillwater to adjust its permitting strategy to address stakeholder concerns, where necessary, and effectively reduce the potential permitting delays and negative comments during public comment periods. A primary focus of the Good Neighbor Agreement is water quality, and under the agreement, the Stillwater and East Boulder Rivers are closely monitored for changes in water quality. The agreement sets water quality triggers that meet or exceed the state and federal requirements. If a Good Neighbor Agreement water quality trigger is exceeded, Sibanye-Stillwater will take the appropriate remedial actions as defined in the agreement. As part of the monitoring, citizens may attend all mine-related water quality inspections and sampling events but are also provided with quarterly water quality reports. A provision is also made for the citizens to conduct independent water quality sampling, if necessary. The Good Neighbor Agreement is also aimed at ensuring public safety and security by restricting mine traffic and monitoring Sibanye-Stillwater’s adherence to the permitted traffic volumes and speed limits. In order to meet traffic requirements, the agreement provides for carpooling and bussing as a preferable means of transport for mine employees. These arrangements also afford mine workers additional rest time and keep tired drivers off the road.


207 Other aspects of the Good Neighbor Agreement include the following:  Establishing conservation easements on Sibanye-Stillwater owned ranches along the Boulder and Stillwater Rivers;  Preventing any mine-sponsored housing occurring outside existing communities; and  The Good Neighbor Agreement contains no commitments in terms of local procurement and employment. Other social and community activities include the following:  Grazing leases for lands purchased at the Hertzler Ranch area (Ekwortzel Purchase) for Stillwater Mine are tied into the land purchase agreement with the previous landowner by way of a 10-yr option expiring in 2028;  Sibanye-Stillwater has also entered into an agreement with Earthworks and Trout Unlimited regarding the East Boulder Tailings Storage Facilities in 2023. This Agreement allows for: o Sibanye-Stillwater to conduct an analysis of using filtered whole tailings for underground backfill at East Boulder Mine and opportunity to provide input on the scope of the analysis; and o The option to include a technical representative to participate in the Annual Inspection. The Qualified Persons are satisfied with Sibanye-Stillwater’s commitment to working with federal and local administrations, organisations and community and conservation groups to ensure that Stillwater and East Boulder Mines adhere to the Good Neighbor Agreement. Furthermore, the mine plans for Stillwater and East Boulder Mines ensure that commitments made in the Good Neighbor Agreement are not breached. Accordingly, the Qualified Persons are of the view that Sibanye-Stillwater should be able to maintain its Social Licence to Operate the Stillwater and East Boulder Mines for as long as it continues to actively engage other stakeholders and to honour conditions and commitments specified in the Good Neighbor Agreement. Environmental Studies, Permitting and Plans Overview of Environmental Legislation and Regulation Operations at Stillwater and East Boulder Mines are regulated by the State of Montana agencies including the Montana Department of Environmental Quality (DEQ); Department of Natural Resources and Conservation (DNRC); as well as Federal agencies including the Custer Gallatin National Forest (CGNF); US Environmental Protection Agency (EPA); US Bureau of Alcohol, Tobacco and Firearms (ATF); US Army Corps of Engineers; US Federal Communications Commission (FCC); and US Nuclear Regulatory Commission (NRC). A list of the agencies and the required permits, licenses or approvals are presented in Table 49. The regulatory agencies can approve, deny, or conditionally approve applications for mining or modification of permits. State of Montana regulations require that changes to or denial of a permit must be directly related to a specific State law or regulation and are not discretionary. The United States Forest Service (USFS) may deny mining proposals, although this authority is limited by federal law. Several laws (e.g., the 1872 Mining Law as amended and related regulations in Title 36 of the US Code of Federal Regulations (CFR) Part 228A; 1897 Organic Administration Act; and 1955 Multiple Use Mining Act), allow the USFS to reasonably regulate mining to minimize adverse environmental impacts on National Forest surface resources and to ensure compliance with applicable environmental laws and regulations. These laws and regulations include, but are not limited to, the 36 CFR 228 Locatable Minerals Regulations, 208 Subpart A; 1972 Clean Water Act (CWA); and 1973 Endangered Species Act (ESA). The USFS can reasonably regulate mining although it cannot prohibit or unreasonably restrict operations that are otherwise in compliance with law. If analysis performed under the National Environmental Policy Act (NEPA) and other analyses show that a proposed mining activity can operate in a way that is compliant with the applicable environmental laws, the USFS cannot prohibit or deny the proposal on National Forest lands subject to the 1872 Mining Law. The proposals or agency alternatives, if approved, must comply with all applicable federal and state air and water quality laws and regulations. Mine Operating Permits are jointly issued by the State of Montana (DEQ, Hard Rock Mining Program) and the Forest Service, CGNF through a Memorandum of Agreement between the two agencies. The Mine Operating Permits are based on the Plans of Operations submitted by the permittee (which are reviewed by both the State agencies and the CGNF) as well as on the Environmental Impact Statement (EIS) also developed jointly by the DEQ and CGNF, the findings of which are documented in Records of Decision. 209 Table 49: Regulatory Agencies and Permits, Licenses or Approval Requirements Agency, Permit, License, or Approval Purpose US Fish and Wildlife Service (USFWS) Biological Opinion (Endangered Species Act) To ensure actions taken by federal agencies would not jeopardize the continued existence of threatened or endangered species or result in the destruction or modification of critical habitat. The USFS must consult with the USFWS, which issues its Biological Opinion following review of a Biological Assessment submitted by the USFS. US Forest Service (USFS) Biological Assessment Required by the Endangered Species Act prior to the approval of a plan of operations or its implementation. The biological assessment ensures actions taken by USFS would not jeopardize the continued existence of threatened or endangered species or result in the destruction or modification of critical habitat. These are USFS conclusions that usually require USFWS concurrence. Plan of Operations The basis of authorization under statutes administered by the USFS that ensures the design, operation, closure, monitoring, and bonding of mining operations result in adequate operations and reclamation for post-mining land uses. The plan of operations is also needed for activities reasonably incident to mining operations of National Forest lands. Coordination between Montana Department of Environmental Quality (DEQ) and other agencies, as appropriate, per memorandum of understanding between the USFS and Department of State Lands (DSL). The MOU defines the joint administration and bonding of mining operations in Montana with activities on National Forest lands. Executive Order (E.O.) 13007 (Clinton) and Government to Government Relations with Native American Tribal Governments — Memorandum for the Heads of Executive Department and Agencies (April 29, 1994) E.O. 13007 requires that agencies contact Indian tribes regarding effects and the Section 106 regulations require consultation with Indian tribes to identify and resolve adverse effects to historic properties. The Memorandum outlines principles that federal agencies must follow when interacting with federally recognized Native American tribes in deference to Native Americans’ rights to self-governance. Specifically, federal agencies are directed to consult with tribal governments prior to taking actions that affect federally recognized tribes and to ensure that Native American concerns receive consideration during the development of Federal projects and programs. Special Use Permit Allows use of Forest Service Roads Temporary Grazing and Livestock Use Permit Allows non-commercial temporary grazing on Forest Service land FSR Road Maintenance Agreement For situations where the wilderness level of maintenance is not sufficient for a commercial or public user, that user may elect to undertake some or all of the surface maintenance of the FSR as authorized by the Forest Service Road Maintenance Agreement. US Army Corps of Engineers (US ACE) Section 404 Nationwide Permit (Clean Water Act) To control the discharge of dredged or fill material into waters of the US, including wetlands. US Environmental Protection Agency (EPA) Underground Injection Control Permit (Safe Drinking Water Act) EPA regulates the construction, operation, permitting, and closure of injection wells used to place fluids underground for storage or disposal. EPA regulates injection wells at the mines that are used for groundwater remediation and disposal. 210 Agency, Permit, License, or Approval Purpose Delegated Programs EPA has delegated the primary implementation and enforcement authority of the Clean Air Act to Air Resources Management Bureau of DEQ. Similarly, the primary implementation and enforcement authority of the Clean Water Act National Pollutant Discharge Elimination System (NPDES) to the Water Protection Bureau of DEQ under its Montana National Pollutant Discharge Elimination System (MPDES) program. Coordination of these programs is governed by agreements between the EPA and the State of Montana. US Bureau of Alcohol, Tobacco, Firearms, and Explosives (BATFE) Safe Explosives Act The Safe Explosives Act mandated that all persons who wish to receive or transport explosive materials must first obtain a federal explosives license or permit. In addition, the act imposed new restrictions on who may lawfully receive and possess explosive materials. US Bureau of Land Management (BLM) Mineral Claims Under 43 CFR 3700 Part 3800 the BLM manages the subsurface of National Forest lands, while USFS manages the surface. US Mine Safety and Health Administration (MSHA) Federal Mine Safety and Health Act of 1977 as amended by the Mine Improvement and New Emergency Response (MINER) Act Of 2006 Develops and enforces safety and health rules for all US mines regardless of size, number of employees, commodity mined, or method of extraction. MSHA conducts quarterly inspections to ensure safety and health rules are implemented. US Nuclear Regulatory Commission (NRC) Nuclear Density Gauge Permit The NRC licenses the possession and use of portable gauges and any other processes or devices that use radioactive materials. Montana Department of Environmental Quality (DEQ) 401 Certification (Clean Water Act and Montana Water Quality Act) To certify that any activity requiring a federal license or permit that may result in any discharge into State waters would not cause or contribute to a violation of State surface water quality standards. Montana Pollution Discharge Elimination System (MPDES) Permit (Clean Water Act and Montana Water Quality Act) Authorizes discharge to surface water and groundwater adjacent to surface water Operating Permit (Montana Metal Mine Reclamation Act) To ensure design, operation, closure, monitoring, and bonding of mining operations result in adequate reclamation for post- mining use. Coordinate with the USFS, and other appropriate agencies. Storm Water Pollution Prevention Plan (Clean Water Act and Montana Water Quality Act) To prevent the degradation of state waters from pollutants, such as sediment, industrial chemicals or materials, heavy metals, and petroleum products.


211 Agency, Permit, License, or Approval Purpose Short-term Water Quality Standard for Turbidity Related to Construction Activity (318 Authorization of Montana Water Quality Act) To allow for short-term increases in surface water turbidity during construction. Montana Fish, Wildlife, and Parks (FWP) are consulted on this authorization. Air Quality Permit (Clean Air Act and Clean Air Act of Montana) To set allowable air emission rates for both stationary sources and portable emitting units. Non-Community Non-Transient Water Supply (Safe Drinking Water Act and Montana Public Water Supply Act) To ensure safe drinking water supplies for the mine site, and to license the water treatment plant operators. Hazardous Waste Authorization/Classification To allow generation of less than 200lbs of hazardous waste per month as a Conditionally Exempt Small Generator Montana Department of Natural Resources and Conservation (DNRC) Land Use Licenses To permit the construction of access roads and pipelines across State of Montana lands Dam Safety Permit (Montana Dam Safety Act) Montana’s Dam Safety Law requires a dam safety permit for all high-hazard dams. DNRC classified high-hazard dam is a dam with an impoundment capacity of 50 acre-feet or more based on the potential downstream loss-of-life if the dam fails. Water Right Permits (Montana Water Use Act) To permit the legal use/appropriation of water at Stillwater Mine for specified industrial, mining, and water supply beneficial uses. Montana State Historic Preservation Office (SHPO) Historic Resources Consultation (National Historic Preservation Act) To obtain joint approval by land-managing agencies and concurrence by the SHPO before agency approval; reviewed by the Advisory Council on Historic Preservation. Montana Department of Commerce Hard Rock Mining Impact Board Hard Rock Impact Plan To ensure that local government services and facilities will be available when and where needed as a result of new large-scale hard rock mineral developments and that the increased cost of these services will not burden the local taxpayer. The developer identifies and commits to pay all increased capital and net operating costs to local government units that will result from the mineral development. Performed in cooperation with counties, school districts and rural fire districts. County Conservation District 310 Permit (Montana Natural Streambed and Land Preservation Act) To protect and preserve streams and rivers in their natural or existing state. Application processed in consultation with Montana Department of Fish, Wildlife, and Parks. County Road Department Application to Perform Construction Work in a Right- of-Way To permit construction and maintenance of the pipeline along county roads. 212 Environmental Setting and Factors Nye and Absarokee are the closest towns to Stillwater Mine, while McLeod and Big Timber are the closest towns to East Boulder Mine. Facilities at Stillwater Mine are located on both sides of the Stillwater River, which flows southwest to northeast. East Boulder Mine is located on the south side of East Boulder River, which flows north along the mines’ eastern edge and then northwest along the current mine’s northern edge. The East Boulder Mine TSF lies between the Dry Fork Creek and Lewis Gulch drainages. The Columbus Metallurgical Complex is located approximately one-half mile north of the Yellowstone River. The protection of groundwater and surface water is the primary environmental factor for environmental compliance at the Sibanye-Stillwater’s mine facilities. At the Columbus Metallurgical Complex, the primary environmental factor is air quality compliance. Additional environmental factors include air quality, vegetation, soil, geology and geochemistry, wildlife, aquatic resources, cultural resources, aesthetics, and land use. In addition, community approval is often a key factor. The host rock for the J-M Reef has very low acid-generating potential and low metal solubility. This low solubility has minimised potential environmental impacts from the substantial scale of these operations. However, ammonia (NH3), ammonium (NH4+), and nitrate (NO3-) are soluble residual constituents from the ammonium nitrate/fuel oil (anfo) used in mining and have been observed to be present in mine adit waters as well as in leachate from waste rock and tailings. These are the primary potential groundwater and surface water contaminants at the Stillwater and East Boulder Mines. The Stillwater and East Boulder Rivers adjacent to these mines are the principal resources that may be adversely affected by mining operations, although historical and cultural resources are also known to exist within the current and planned mine disturbance areas. The river water quality is high and there is no evidence of adverse impacts to aquatic or terrestrial wildlife populations, although the rivers have measurable loading of nitrates and dissolved solids from mining operations resulting in localised impairment of periphyton and macroinvertebrates. The Stillwater and East Boulder Rivers are considered substantial fishery resources and host brown trout, rainbow trout, brook trout, and mountain whitefish (DEQ and USFS, 1985). Overall, both rivers have good insect and periphyton diversities and densities. Environmental Studies 17.2.3.1 Overview of Baseline and Environmental Studies Extensive baseline and recent environmental studies have been completed since the 1930s for Stillwater Mine and 1982 for East Boulder Mine. For Stillwater Mine and the East Boulder Mine, these entailed surface water and groundwater studies, vegetation studies, wildlife studies, aquatic studies, cultural resource studies, land use studies, aesthetic value and noise studies as well as geological studies. Additional environmental studies were completed in 2021 through 2023 for the expansions at both mines. The content and results of these numerous studies are too voluminous to reproduce herein and, therefore, summaries of key environmental areas are provided below. 213 17.2.3.2 Stillwater Mine and Hertzler Ranch Facilities Extensive environmental baseline and operational monitoring studies have been performed at Stillwater Mine. The 1985 Environmental Impact Study (EIS) for the Stillwater Mine identifies thirteen vegetation types in the study area, along with water and disturbed areas with no vegetation (DEQ and USFS, 1985). These vegetation types include stony grassland, Sagebrush and Skunkbush shrubland, drainage bottomland, riparian woodland, ravine aspen-chokecherry, open forest-meadow understory, open forest-rocky understory, Douglas-fir forest, Lodgepole pine forest, subalpine forest, and cultivated hayland. Timber resources in the mine areas are described generally as being of low commercial value due to poor quality timber and the rugged terrain’s limits on harvest operations. Wildlife studies indicate that the mine areas support diverse and abundant wildlife populations, including bird, mammal, reptile, amphibian, and aquatic species. The mine areas provide winter ranges for elk, mule deer, and bighorn sheep. In addition, the mine area habitats also host moose, black bear, mountain goats and mountain lions. Wildlife habitat types correspond closely to vegetation types previously described. Both the Bald Eagle and the American Peregrine Falcon, which were identified as listed species in the 1985 Stillwater Mine EIS, have been de-listed due to the recovery of their populations. Some of the mine areas provide habitat suitable for wolverines which were identified as a listed species in January 2024 (i.e. at the time of compiling this TRS). The effects of this listing have yet to be determined. Geochemical studies and operational environmental monitoring data demonstrate that the waste rock mined throughout the history of production at the Stillwater and East Boulder Mines have negligible potential to generate acid or acid mine drainage. Concurrent leach testing of over 40 parameters including 29 trace metals from tailings and waste rock indicates that dissolved trace metal concentrations will not exceed current groundwater protection standards. Decades of operational environmental monitoring data are consistent with this testing. However, ammonia (NH3), ammonium (NH4+), and nitrate (NO3-) are soluble residual constituents from the anfo (ammonium nitrate/fuel oil) used in mining and have been observed to be present in mine adit waters as well as in leachate from waste rock and tailings. These are the primary groundwater and surface water contaminants at the Stillwater and East Boulder Mines. The most recent Stillwater Mine environmental studies have addressed baseline biological conditions in Nye Creek and the Stillwater River, groundwater conditions at the Hertzler TSF, climatological conditions, and wetlands delineations at the East Waste Rock Storage Facility expansion area. These studies have been reviewed and accepted or are in review by the regulatory agencies (i.e., DEQ, USFS and USFWS) and to date have been deemed adequate to document baseline conditions for groundwater, surface water, soils, geology and geochemistry, vegetation, wildlife, aquatic resources, cultural resources, aesthetics, and land use to support regulatory approval of ongoing operations. Table 50 identifies the recent environmental studies executed as part of the mine expansion efforts. Tables identifying applicable baseline studies are included in the Consolidated Operations and Reclamation Plans for Stillwater Mine. 214 Table 50: Summary of Recent Environmental Studies Associated with Expansions at Stillwater Mine Date Description 2019/01/15 Nye Creek Biological Baseline Summary: Fish, Macroinvertebrates, Periphyton and Chlorophyll-a Sampling 2019/08/30 Climatological Site Conditions 2019/09/25 East Boulder Mine Geological and Geotechnical Site Conditions 2019/12/01 Draft Vegetation Baseline: (ESWRSF & Hertzler TSF) 2019/12/16 Analysis of Stillwater Valley Ranch Trout Ponds as a Receiving Water for Discharges to the SVR Percolation Ponds 2020/01/01 Biological Resource Survey; brief reconnaissance of biological resources of Hertzler TSF and ESWRSF; the expansion sites and Stillwater Mine vicinity do not support preferred and/or breeding habitat and preferred and/or breeding habitat is available in the vicinity 2020/03 Biological Assessment of Sites in the Stillwater River Drainage, Stillwater County, Montana: Macroinvertebrates, Periphyton, and Chlorophyll a, 2019 2020/06/25 Cultural resource survey results 2020/06/25 Mine East Dump; Cultural resource survey results 2020/06/30 Aesthetics/Viewshed 2020/12 Biological Assessment of Sites in the Stillwater River Drainage, Stillwater County, Montana: Macroinvertebrates, Periphyton, Chlorophyll a, and Periphyton Ash-Free Dry Mass 2020 2021/1 Biological Resources Reconnaissance, Sibanye-Stillwater: Stillwater Mine Hertzler Tailings Storage Facility and East Side Waste Rock Storage Facility Expansions Rev 1 2021/1/5 2020 Site Investigation Summary – East Side Waste Rock Storage Facility 2021/1/6 Hertzler Valley Groundwater Assessment – Status Update 2021/01/29 Geological and Geotechnical Site Conditions – Hertzler Ranch 2021/01/29 Geological and Geotechnical Site Conditions – Hertzler Ranch 2021/2 Stillwater East Dewatering Project Water Study Update Report 2021/? Hertzler Valley Groundwater Level Assessment – Status Update 2021/9/27 Waste Rock Storage Area Closure Scenario 2021 Benbow Portal Area 2022/1/20 East Side Injection Well Installation & Aquifer Testing 2022/2 East Side Waste Rock Storage Facility: A Class III Cultural Resource Inventory Rev 1 (Confidential) 2022/2 Hertzler Tailings Storage Facility Expansion: A Class III Cultural Resource Inventory Rev 1 (Confidential) 2022/2/23 Geological And Geotechnical Site Conditions Report – Stillwater Mine Site 2022/6/17 Nye Flood Event Geotechnical Recommendations 2022/7/26 Stillwater Mine Flood 2022 404 Emergency Authorization Construction Memo 2022/8/23 Stillwater Mine Ordinary High Water Mark Survey Report 2022/8/26 Benbow Portal Heater Noise Modelling Report Rev 2 2022/10 Testing Results of Three Prehistoric Sites in the Hertzler Tailings Storage Area near Nye, Stillwater County, Montana (Confidential) 2022/11/1 Benbow Portal Heater Ambient Sound Level Survey 2022/12 Biological Assessment of Sites in the Stillwater River Drainage, Stillwater County, Montana: Macroinvertebrates, Periphyton, Chlorophyll A, And Periphyton Ash-Free Dry Mass 2023/3/30 Stillwater Mine Climatological Site Conditions Rev 1 2023/4/6 Proposed Hertzler Stage 4 and Stage 5 TSF Groundwater Monitoring Technical Memo 2023/6 SWM Conceptual Site Model – East Side Waste Rock Storage Area 2023/8/14 Stillwater Mine’s Benbow Portal Waste Rock Storage Area Closure Specifications Memo


215 Date Description 2023/8 Nye Creek Morphology Assessment Final Report 2023/9/21 Nye Creek Biological Baseline Summary: Fish, Macroinvertebrates, Periphyton and Chlorophyll-a Sampling Rev 2 2023/10/6 East Side Waste Rock Storage Facility Storm Water Mixing Analysis 2023/10/30 East Side Waste Rock Storage Facility Proposed Expansion Closure Analysis Rev 2 2023/10 East Side Waste Rock Storage Facility and Hertzler Tailings Storage Facility Expansion Vegetation Baseline Rev 1 2023/11 Visual Assessment of the East Side Waste Rock Storage Facility and Hertzler Ranch Tailings Storage Facility Expansion – Stillwater Mine Baseline Technical Memorandum 2023/11 Stillwater Mine MA 014 Soil Baseline Characterization Rev 1 2023/12/21 Final 2023 OHWM Delineation Report 2024/2/7 Analyses of June 2022 Flood Flows at Stillwater and East Boulder Mines 2024/3/1 Sibanye-Stillwater 2023 Groundwater Dependent Ecosystem (GDE) Inventory Nye Mine – East Blitz Project 2023/12 SWM Biological Monitoring Report 2024/2/7 Analyses of June 2022 Flood Flows at Stillwater and East Boulder Mines 2024/3/1 Sibanye-Stillwater 2023 Groundwater Dependent Ecosystem (GDE) Inventory Nye Mine – East Blitz Project 17.2.3.3 East Boulder Mine Baseline data for East Boulder Mine was collected between 1982 and 1992 to support the 1992 Environmental Impact Statement. Additional baseline data was collected between 1997 and 2023 to support water management and additional expansions at the mine. The geology of East Boulder Mine comprises unconsolidated alluvium and glacial deposits overlying Palaeozoic sedimentary bedrock and igneous bedrock of the Stillwater Complex (DEQ and USFS, 2020). Groundwater in the Stillwater Complex occurs primarily in an extensive network of joints, fractures and fault zones resulting in slow groundwater flow. The glacial deposits vary in grain size and are a mixture of boulder, gravel, sand and silt sized particles, which result in variable groundwater flow rates. The majority of recharge to the underlying glacial deposits and bedrock is understood to occur through the alluvial deposits (DEQ and USFS, 2020). Groundwater occurs beneath the East Boulder Mine at depths from 120ft to 150ft below the ground surface but follows the ground surface and becomes shallower near the East Boulder River (DEQ and USFS, 2020). Groundwater flows from southeast to northwest parallel to the axis of the valley that contains the East Boulder Mine. The groundwater quality in the East Boulder Mine footprint has low total dissolved solids concentrations and low concentrations of sulphate, chloride and heavy metals. The East Boulder River adjacent to the East Boulder Mine is characterized by riffles and pools. Peak flows in the East Boulder River result from snowmelt and precipitation. The river loses water to the groundwater system northeast of the permit area and gains water from the groundwater system farther downstream along the East Boulder Mine. The water quality of the East Boulder River is good, with low total dissolved solids concentrations. Total dissolved solids concentrations vary with river flow; higher total dissolved solids concentrations are measured during times of lower flow in the winter and early spring. Sampling of the aquatic environment of the East Boulder River for thirteen years identified that the river had 216 excellent biotic integrity and no impairment of water quality of biological integrity resulting from East Boulder Mine operations has been identified. The Lewis Gulch drainage has surface water flow along portions of the drainage in response to snowmelt. Three springs along the Dry Fork drainage flow for distances before infiltrating into the ground. Flowing surface water did not intercept the East Boulder River during baseline studies. The surface water in the Lewis Gulch and Dry Fork drainages is high quality with low total dissolved solids and metals concentrations. Four distinct plant communities are located within the East Boulder Mine boundary. These include Mature Douglas Fir Forest, Early Seral Douglas Fir Forest, Reclaimed Grassland, and Meadow Grassland. No threatened or endangered plant species were identified as occurring at the East Boulder Mine. One sensitive species (Whitebark pine) was identified in the area of the proposed future disturbance at East Boulder Mine. The most recent East Boulder Mine environmental studies have addressed baseline environmental conditions, cultural resources surveys, wetland surveys, mine groundwater inflow, climatological conditions, and biological assessment of the East Boulder River. The Class III cultural resource inventory study completed in 2021 identified from records seven previously identified cultural sites within the study area but did not identify evidence of those sites in the recent field survey of over 315 acres and no further survey work was recommended. The survey did not identify any sites that would preclude the planned expansions. Wildlife studies indicate that the area around East Boulder Mine supports diverse and abundant wildlife populations. The mine areas provide winter ranges for elk and mule deer. In addition, the mine area habitats host moose, black bear, grizzly bear, and wild trout. Brown trout and rainbow trout are the most abundant species in the East Boulder River (DEQ and USFS, 2012a). The recent baseline study Construction and operation of the TSF and Dry Fork waste rock storage facilities would result in short- term and long-term impacts on wildlife use patterns, wildlife habitat quantities, and vegetative composition. The project may decrease wildlife forage production and availability in the short term due to the removal of vegetation. Possible adverse effects to aquatic resources in the East Boulder River or the perennial or ephemeral streams could result from soil erosion / storm water discharges occurring during construction. However, wildlife carrying capacity may increase in the long-term after the project is complete and the project area is revegetated. Effective January 2024, the USF&W Service listed the wolverine as a threatened species. Some of the East Boulder Mine site areas have been identified as having the potential for wolverine habitat. Impacts have yet to be determined. All ecological, geological, hydrological, geotechnical, archaeological, and climatological studies appear to be completed for the Lewis Gulch TSF Stage 4 and 5 expansions, the Dry Fork Waste Rock Storage Area and associated haul road and bridge. 217 The baseline studies have been reviewed and accepted by the regulatory agencies after having been deemed adequate to document baseline conditions for groundwater, surface water, soil, geology and geochemistry, vegetation, wildlife, aquatic resources, cultural resources, aesthetics, and land use to support regulatory approval of operations. Table 51 identifies the recent environmental studies executed at East Boulder Mine. Tables identifying applicable baseline studies are included in the Consolidated Operations and Reclamation Plans for East Boulder Mine. Table 51: Summary of Recent Environmental Studies Associated with Expansions at East Boulder Mine Date Description 2019/09/25 Geological and Geotechnical Site Conditions 2020/12 Biological Assessment of Sites on the East Boulder River: Sweet Grass County Montana, 2020 2021/10/14 Climatological Site Conditions 2021/05 Lower Lewis Gulch and Dry Fork Sites Wetland Survey 2021/05 Lewis Gulch and Dry Fork Creek Updated Baseline Hydrogeologic Monitoring Report 2021/06/21 East Boulder Mine Groundwater Inflow Analysis 2021/08 East Boulder Expansion: A Class III Cultural Resource Inventory in Sweet Grass County, Montana 2021/08 Baseline Environmental Survey at the East Boulder Mine 2021/10/14 East Boulder Mine Climatological Site Conditions 2021/11 Monitoring of Chlorophyll-a and Periphyton Ash-Free Dry Mass on the East Boulder River, Sweet Grass County Montana, 2021 2022/1/12 Closure Analysis of the East Boulder Mine Stage 6 Embankment Underdrain Collection System 2022/1/20 2022 CGNF Site Wide Biological Opinion 2022/1/28 GNA Water Treatment Optimization Memo 2022/2/11 EBM Future TSF and WRSA Options Assessment 2022/3/9 Updated Closure Analysis of the East Boulder Mine Waste Rock Storage Area Underdrain Collection System with Passive Water Treatment 2022/3 East Boulder Mine 2020 Water Management Plan Revision 1 2022/8 Energy Use Assessment for Sibanye-Stillwater Mine Sites 2022/9/9 East Boulder Amendment 4 Wetlands Delineation Report 2022/10/24 East Boulder Tailings Materials Testing Report Final 2022/11/7 East Boulder Mine Subsidence Adherence Memo 2022/12/9 East Boulder Mine Major Amendment 004 Supplemental Delineation Report 2022/12 Biological Assessment of Sites on the East Boulder River: Sweet Grass County, Montana, 2022 2022/12 East Boulder Mine 2022 Groundwater Dependent Ecosystem Survey Phase 1 2023/1/6 East Boulder Mine Filtered Tailings Summary Report 2023/1/11 East Boulder Mine Filtered Tailings Options Study 2023/2 Biodiversity Impact Assessment for 2021, US PGM Operations 2023/3/27 East Boulder Mine Whole Mill Tailings as Back Fill Memo 2023/11 East Boulder Mine 2023 Nitrogen Loading Analysis Memorandum 2023/11/27 East Boulder Mine Amendment 004 EIS – Tech Memorandum 1 – Review of Dry Fork Waste Rock Storage Area Nitrate Attenuation and Potential Duration of Active Water Treatment 2023/11/27 East Boulder Mine Amendment 004 EIS – Technical Memorandum No. 2 – Review of Dry Fork Waste Rock Storage Area Reclamation and Capping Alternatives 2023/11/27 East Boulder Mine Amendment 004 EIS – Technical Memorandum No. 3 – Tailings Management Alternatives to Slurried Impoundment Deposition 2024/2/7 Analyses of June 2022 Flood Flows at Stillwater and East Boulder Mines 218 17.2.3.4 Metallurgical Complex No baseline studies, environmental studies nor impact assessments specific to the Columbus Metallurgical Complex (smelter and base metal refinery) were completed for permitting purposes as these were not required by the regulatory authorities. As there was no public land interaction and associated permitting, an EIS or similar studies were not required for construction and operation of the smelter and base metal refinery. Permitting Status and Compliance 17.2.4.1 Overview of Permitting Status Permits from the Federal, State and local agencies for the Sibanye-Stillwater US PGM Operations include permits from the State of Montana (e.g., mine permit, air quality permit, stormwater discharge permits, water discharge permits, exploration permit, and potable water supply permit, dam safety and water rights), and permits from the US Environmental Protection Agency (EPA) and US Forest Service (USFS). The county conservation districts provide permits to protect and preserve streams and rivers, whereas the road departments provide permits for access to conduct activities in road rights of way. Table 52 summaries the existing permits and their status for the Sibanye-Stillwater US PGM Operations. Mining occurs on Federal lands managed by the USFS and on private land. Most of the private land is historic patented mining claims which are now private. Those private lands not currently owned by Sibanye-Stillwater are leased. Federal lands and permission to access the surface for mining purposes is applied for and granted by the USFS in conjunction with the NEPA process and technical application to the USFS and DEQ. The Qualified Persons conclude that most of the key approvals have been granted and are reasonably anticipated to continue to be granted for mining and processing operations for the foreseeable future. 17.2.4.2 Stillwater Mine and Hertzler Ranch Facilities Specific permitting requirements vary widely by agency and regulated media and these are described in USFS and DEQ regulations and associated guidance. All necessary permits and approvals are in place and adequate for existing operations. Permits and licenses requiring renewal in FY2023 have been developed in a timely manner and submitted to the regulatory agencies for approval and efforts initiated for permits and licenses needing renewal in FY2024. Permits and approvals are tracked and renewal dates, schedules, timeframes and requirements for continued compliance are addressed in a timely manner with few exceptions. Reclamation bonding is required under the Operating Permit (No. 00118). Bonding is addressed in the Section 0 (Reclamation Plans and Costs). Permitting for planned expansions have been initiated in a timely manner and appear to be on track for schedule changes in operations. There are three current violations of the Operating Permit No. 00118 and two of the Exploration License No. 00046 relating to nitrate concentrations in groundwater and surface water, and submittal of Water Resource Management Reports (WRMR) and Biological Monitoring Reports beyond their prescribed


219 deadlines. These violations were issued between December 2019 and February 2020. The December 2019 and February 2020 DEQ letters identified violations related to the following:  Stillwater (Operating Permit No. 00118): o 12/13/19 -Stillwater Mine:  00039- Exceedances of nitrate+nitrite levels in East Side Waste Rock Storage Facility groundwater monitoring well MW-18A (>10mg/l), which are located downgradient of the East Side Waste Rock Storage Facility and up-gradient of the Stillwater River. Elevated concentrations relate to seepage of meteoric waters through the East Side Waste Rock Storage Facility materials that accumulate nitrogen from traces of residual anfo. Resolved through AOC;  00039 – Failing to submit a plan (or third-party review/report) for agency review and approval and falling to take prompt and appropriate remedial corrective measures to address the exceedance in HMW-10 at the Hertzler TSF. Resolved through AOC;  00039- Failure to submit required 2018 Water Resource Monitoring Report and Biological Monitoring Reports by the June deadlines. Resolved through corrective action and required biological monitoring took place in 2020. o 1/30/2020 – Benbow; Exploration Permit 0046; o 00040- Exceedances of nitrate+nitrite levels in BMW-3. Elevated concentrations relate to seepage of meteoric waters through the Benbow Waste Rock Storage Area materials that accumulate nitrogen from traces of residual anfo. Resolved through AOC; o 00040- Exceedance of Numeric Nutrient Standard in Benbow Mill Site Creek (BMSCR). Resolved through corrective action and installation of Permeable Reactive Barrier and initiation of BMW-3 as a pump back well; o 00040- 2018 Annual Water Resources Monitoring Report was submitted on December 31, 2019, six months after due date. Resolved through corrective action; Water Resources Monitoring Plan Submitted to DEQ; o 02/04/2020 Stillwater Mine:  00041 – Exceedances of nitrate+nitrite levels in East Side Waste Rock Storage Facility groundwater monitoring well MW-14A. Dismissed based on CORP Stipulation 21;  00041- Failing to notify Agency of any corrective actions taken to address the change in groundwater Quality in MW-14A. Resolved through AOC;  00041-The 2018 Annual Water Resources Monitoring Report was submitted on December 31, 2019, six months after due date. Resolved through corrective action. Water Resources Monitoring Plan submitted to DEQ;  00041- The 2018 Annual Biological Monitoring Report was submitted on December 31, 2019, six months after due date. Resolved through corrective action Biological Monitoring Plan submitted to DEQ; o 03/25/2022 – Hertzler:  Exceedance of Water Quality Standard (HMW-16). Resolved through AOC;  Departure from approved Plan: Water Resource Monitoring Plan. Resolved through AOC; o 06/07/2022 Stillwater Valley Ranch (SVR):  00073- Exceedance of Water Quality Standard SVR Well Nitrate +Nitrite 10mg/l and Non-degradation Standard of 7.5mg/l. Resolved through AOC; o 09/06/2023 Stillwater Mine: 220  MPDES Permit MT0024716 – Montana DEQ Water Protection Bureau issued a violation letter regarding self-reporting noncompliance reports on June 20, 2023, due to a tear in Pond 3 liner, August 1, 2023, when pond 2 overflowed into pond 3 and finally on August 8, 2023, when the water treatment plant cell overtopped and treated water went into Mountain View Creek. Stillwater Mine initiated implementation of corrective actions at the East Side Waste Rock Storage Facility in 2016 with agency knowledge, although approved plans were not formally submitted or approved. Although water quality standards have been exceeded due to seepage from the East Side Waste Rock Storage Facility, no beneficial uses in the Stillwater River have been impacted or compromised with respect to surface water quality or residential groundwater supplies. DEQ has stated that the resolution of these violations will be dependent on the timely initiation of the meeting with DEQ and USFS, the timely implementation of remedial corrective actions, and the submittal of documentation of the corrective actions specified in the Consolidated Operations and Reclamation Plan. Corrective actions at the East Side Waste Rock Storage Facility have been initiated since 2016 and include synoptic monitoring, phased East Side Waste Rock Storage Facility lining and Nitrogen Collection Pond installation, consultant evaluation of water quality changes (2018 and 2019) and initiation of in situ treatment of nitrogen with methanol injection. Corrective actions at the Hertzler TSF include repair of the liner tear (during 2015), installation of groundwater capture French drains and pump back system, installation of in-situ remediation, synoptic and biological monitoring on Stillwater River at Hertzler Ranch, and additional well installations. Corrective actions have been implemented at the Benbow Waste Rock Storage Facility and Benbow Mill Spring Creek. Corrective actions include synoptic monitoring of Benbow Mill Site Creek and Little Rocky Creek, installation of groundwater collection vaults for foundation drains (beneath waste rock storage area and WTP2 feed pond) and pump back of collected groundwater for treatment, as well as installation of a permeable reactive barrier (PRB) treatment system using methanol injection. Monitoring data indicates water quality concentrations in the creeks have returned to below regulatory levels, indicating successful implementation of the PRB, although groundwater concentrations remain above regulatory standards. The Qualified Persons conclude that the corrective actions implemented appear to have reasonable effectiveness and, where water quality has not yet been restored to below levels of regulatory concern, water quality concentration trends show stable to downward progression. Most of the violations have been resolved and closed while a few remain open at the time of the report. Closeout of the remaining violations is pending further monitoring and regulatory acceptance of corrective action completion. 17.2.4.3 East Boulder Mine Permits required for current operations at East Boulder Mine include permits from the State of Montana (e.g., mine permit, air quality permit, stormwater discharge permits, water discharge permits, exploration permit, and potable water supply permit), and permits from the Federal government including the EPA and USFS. There are two open regulatory violations at the time of compiling this TRS and these are described as follows: 221  09/12/2023: o Notice of Non-Compliance – USFS issued a Notice of Noncompliance for Unauthorized activities on NFS lands associated with the BVR Heat Exchanger Project. Project site access road encroached onto the USFS Swan 2 unpatented claim;  09/14/2023: o 00102-Montana DEQ Hard Rock Mining Bureau issued a violation for ‘'Departure from Conditions of Approved Operating and Reclamation Pla'. In MR23‐002, SMC had committed to overland transportation of construction equipment to the vent raises using an access path solely on SMC patented claims. Furthermore, no reclamation of the path was included in the revision or accounted for in the reclamation bond, since it was intended to be an overland access path without removal of timber. Due to winter conditions, access to the BVR Heat exchanger locations referenced above is not available until after spring snow melt. Therefore, final reclamation of the location to conform to the two violations listed above cannot be completed until spring 2024. Plans are in place to execute reclamation in spring of 2024. Federal permits from the EPA are for Class V groundwater injection wells. These Class V injection well permits address the following:  Recycling of water back into the mine (MT5000-05150);  Disposal of septic system water (MT50000-06439);  Disposal of treated adit water from the underground workings (MT50000-11713); and  Injection of methanol into shallow alluvial groundwater for in situ biological reduction of nitrates (MT50000-008511). An amendment to Operating Permit No. 00149 for the development of the Lewis Gulch TSF and the Dry Fork WRSF has been submitted to the Agencies. This amendment includes a 404 Permit with the US Army Corps of Engineers (ACOE) for the waste rock haulage crossing. The DEQ and USFS have prepared an Environmental Impact Statement for the Lewis Gulch TSF and the Dry Fork WRSF Expansion Project, and the public comment period has ended and a ROD is expected to be issued second quarter 2024. East Boulder Mine is approved to discharge from three outfalls into the East Boulder River and groundwater in an alluvial aquifer under MPDES Permit MR-0026808. A permitted injection well for treated mine water at the Yates Gravel Pit is permitted and infrastructure is in place but as of this review, the system has not yet been operated. Groundwater monitoring between 2005 and 2010 detected concentrations of nitrate as nitrogen greater than the non-degradation level established in the MPDES permit in three monitoring wells downgradient of the tailings storage facility and the infiltration pond. The DEQ found the mine out of compliance with the MPDES permit (MT0026808), triggering SMC (the owner at the time) and the DEQ to enter into an Administrative Order on Consent (Docket No., WQA-10-04). A compliance plan was submitted to DEQ and approved to establish a series of corrective actions to address the exceedance of the MPDES nitrate as nitrogen limits. In addition, a groundwater capture and pump back system was constructed and became operational in 2011. In situ treatment wells were installed and reagent was injected into injection wells to reduce nitrates as nitrogen concentrations. A TSF embankment underdrain system was also installed to collect meteoric water through the embankment rock fill and 222 route the water back to the supernatant pond. An outer embankment liner was installed along the outer TSF Stage 3 slope to reduce infiltration of meteoric water through the embankment rock. As a result of the corrective actions, nitrate as nitrogen concentrations in downgradient monitoring wells were reduced to 35% of the non-degradation standard for groundwater in 2017. In 2017, the DEQ approved a mixing zone which resulted in a zone across which cumulative contributions from operational sources within the permit boundary are addressed. In January 2018, DEQ found that the Sibanye-Stillwater (SMC) is in compliance with the MPDES Permit and that the terms of the Consent Order were satisfied. The Qualified Persons conclude that long-term groundwater and surface water restoration and protection from operational impacts are ongoing and well managed, and compliance is likely to be achieved and maintained. 17.2.4.4 Columbus Metallurgical Complex The smelter at the Columbus Metallurgical Complex has only two permits, namely a Montana Air Quality Permit (#2635-17) from the DEQ Air Resources Bureau, and a MPDES Permit (-000469) with the DEQ Water Protection Bureau, both which are current and in good standing. The Qualified Persons understand that these permits are current and not due for renewal for several years. The Air Quality Permit (MAQP No. 2635-19) limits air emissions based on measured opacity, particulate emissions (PM10) from baghouse filters, and Sulphur dioxide (SO2) emissions based on maximum allowed smelter concentrate throughput (≤59 500 tons/year), precious metals recyclable material through put (≤15 000 tons/year), gypsum production (≤25 000 tons/rolling 12-month period), smelter slag production (≤60 000 tons/rolling 12-month period), the amount of waste ore for lining the slag pits (≤40 000 tons/rolling 12-month period), and emergency back-up generator run time (≤500 hours/rolling 12-month period). Emissions testing requirements of the Air Permit include:  Particulate and opacity performance source tests every two years on the smelting circuit main stack and concentrate drying circuit main stack;  Particulate and opacity performance source tests every five years on the process baghouse for the nickel sulphate crystal dryer; and  SO2 performance source testing on the smelting circuit stack every five years. In addition, Continuous Emissions Monitoring System (CEMS) to monitor stack volumetric flow rate and record SO2 emissions are operated and maintained as required. Reporting of testing and monitoring results as well as material inventories is provided annually. The MPDES permit for stormwater contains non-numeric technology-based effluent limits and numeric water quality-based effluent limits. Non-numeric technology-based effluent limits include best management practices for managing materials to minimize contact with site waters, control site materials from egress, maintenance and erosion control practices. Numeric water quality-based effluent limits are established as well as benchmark and outfall monitoring requirements. However, the smelter operates in a zero-discharge mode with all stormwater contained onsite, following the storm


223 water pollution prevention plan and best management practices with all storm water retained via use of berms, ditches and percolation ponds. All permits have been renewed or revised in a timely manner. There are no performance or reclamation bonds associated with this facility. 224 Table 52: Permits Status Summary for the Sibanye-Stillwater US PGM Operations Site Operating Permit and Type Status Permit Number Regulatory Agency Discharge Type Date Issued Renewal Date Description Stillwater Mine Operating Permit and Type Status Permit Number Regulatory Agency Discharge Type Date Issued Renewal Date Description Original Permits Plan of Operations (POO) Active 118 USFS Custer Gallatin National Forest (CGNF)/ DEQ Hard Rock Mining Program Feb-90 NA Plan of Operations Original (EIS) Record of Decision Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Jan-86 NA Mine Permit Stillwater Mine Operating Permit Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Jan-86 NA Operating Permit #00118 - Approved by ROD in December 1985 Amendments Operating Permit Amendment No. 1 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Jun-86 NA Plant site relocation Operating Permit Amendment No. 2 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Sep-86 NA Sand borrow area approved Operating Permit Amendment No. 3 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Jan-87 NA Second sand borrow area approved Operating Permit Amendment No. 4 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Feb-87 NA Nye Tailings Impoundment toe dike relocation Operating Permit Amendment No. 5 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Mar-89 NA East-side development approved (increase permit area) Operating Permit Amendment No. 6 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Jul-89 NA Temporary sand pipeline approved 225 Site Operating Permit and Type Status Permit Number Regulatory Agency Discharge Type Date Issued Renewal Date Description Operating Permit Amendment No. 7 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Nov-90 NA Adit relocated, 3 perc ponds added, 5 monitoring wells added Operating Permit Amendment No. 8 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Sep-92 NA Facilities expansion, production increase to 2000 ton/day Operating Permit Amendment No. 9 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Mar-96 NA East-West mining areas connected with haulage way (mining under Stillwater River) Operating Permit Amendment No. 10 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Nov-98 NA Hertzler expansion approved and production cap eliminated Operating Permit Amendment No. 11 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Aug-12 NA Revised Water Management Plan at Stillwater, Hertzler LAD (closure/post-closure), Boe Ranch LAD (operations/closure/post- closure) Stillwater Mine Operating Permit Amendment No. 12 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Jul-10 NA Addition of Hertzler LAD Pivot #7 226 Site Operating Permit and Type Status Permit Number Regulatory Agency Discharge Type Date Issued Renewal Date Description Operating Permit Amendment No. 13 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program May-23 NA Incorporated the Benbow Exploration Project into Mine Permit 00118 Operating Permit Amendment No. 14 Pending 118 USFS CGNF/ DEQ Hard Rock Mining Program Pending Minor Revisions Operating Permit Minor Revision 89-001 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Dec-89 NA Waste rock haulage railroad spur at 5150W Adit Operating Permit Minor Revision 90-001 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Jul-90 NA 5200E Ventilation Adit with auxiliary facilities Operating Permit Minor Revision 90-002 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Sep-90 NA Sediment basin construction (no new permit area) Operating Permit Minor Revision 91-001 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Jun-91 NA 5200E Portal, spur road, laydown, and access road Operating Permit Minor Revision 91-002 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Oct-91 NA Compressor pipeline crossing at Stillwater River Bridge Operating Permit Minor Revision 92-001 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Mar-92 NA 5000E loci haul rail track extension Operating Permit Minor Revision 92-002 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program 1992 Permanent 5400E waste rock pile, eliminate laydown


227 Site Operating Permit and Type Status Permit Number Regulatory Agency Discharge Type Date Issued Renewal Date Description Operating Permit Minor Revision 93-001 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program 1993 NA 5300W ventilation improvements, 5400E rail haulage improvements Operating Permit Minor Revision 93-002 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Sep-93 NA Compliance timeframe extension for Amendment 8 stipulations Operating Permit Minor Revision 93-003 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Oct-93 NA 6500W secondary escape way installation Operating Permit Minor Revision 94-001 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Mar-94 NA Expansion of OP boundary to include Stillwater Valley Ranch Operating Permit Minor Revision 94-002 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program May-94 NA Construction of west-side production shaft (location change) Operating Permit Minor Revision 94-003 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Jul-94 NA Tree planting to visually screen mine site facilities Operating Permit Minor Revision 94-004 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Nov-94 NA Boulder storage area permitting in north area of permit boundary Operating Permit Minor Revision 95-001 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Mar-95 NA Road relocation on Nye TSF embankment 228 Site Operating Permit and Type Status Permit Number Regulatory Agency Discharge Type Date Issued Renewal Date Description Operating Permit Minor Revision 95-002 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program 1995 NA Relocate west-side low grade ore stockpile to east-side Operating Permit Minor Revision 96-001 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Feb-96 NA Waste rock processing to augment coarse tailings backfill Operating Permit Minor Revision 96-002 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Dec-96 NA Smelter waste disposal (gypsum and slag) in Nye TSF Operating Permit Minor Revision 97-001 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Jan-97 NA Plan of Ops revision to construct Outfall 001 (not constructed) Operating Permit Minor Revision 97-002 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Aug-97 NA Modify Nye TSF liner to lower final elevation (5111 to 5108) Operating Permit Minor Revision 97-003 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program 1998 NA Mine plan revision to extend 4400W level under the river Operating Permit Minor Revision 98-001 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Jul-98 NA Mine site facility additions (mill building, paste backfill plant, jaw crusher at west rail, covered conveyors from ore silo, service pipelines crossing river) 229 Site Operating Permit and Type Status Permit Number Regulatory Agency Discharge Type Date Issued Renewal Date Description Operating Permit Minor Revision 98-002 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Dec-98 NA Mine site facility additions (maintenance dry & change house, office dry and change house, oil/drum storage, tire shop, water treatment plant addition) Operating Permit Minor Revision 99-001 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Sep-99 NA Mine site facility additions (concrete sewage vault, filter press addition in concentrator) Operating Permit Minor Revision 99-002 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Aug-99 NA Staged development plan for East-Side Waste Rock Storage Area Operating Permit Minor Revision 00-001 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Mar-00 NA BTS expansion from 4 to 6 denitrification cells Operating Permit Minor Revision 00-002 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Mar-00 NA Expansion of concentrator floatation circuit, installation of Larox Operating Permit Minor Revision 00-003 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program May-00 NA Hertzler pipeline route change (avoid culturally sensitive area) 230 Site Operating Permit and Type Status Permit Number Regulatory Agency Discharge Type Date Issued Renewal Date Description Operating Permit Minor Revision 00-004 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Jul-00 NA Dow Meadow Vent Raise (6500W) final location Operating Permit Minor Revision 01-001 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Mar-01 NA 5000E compressed air line install, extension of rail on 5000W dump Operating Permit Minor Revision 01-002 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Sep-01 NA Comprehensive mine site development plan (east and west side additions) Operating Permit Minor Revision 01-003 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Sep-01 NA East-side compressor building addition Operating Permit Minor Revision 01-004 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Sep-01 NA Warehouse addition (north-side of 5150W Paste Plant) Operating Permit Minor Revision 01-005 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Mar-02 NA Two paste backfill lines to 4400W Operating Permit Minor Revision 01-006 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Mar-02 NA East-side parking area for additional vehicles Operating Permit Minor Revision 03-001 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Apr-03 NA Hertzler TSF Stage 2 final design and LAD storage pond


231 Site Operating Permit and Type Status Permit Number Regulatory Agency Discharge Type Date Issued Renewal Date Description Operating Permit Minor Revision 03-002 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Jul-03 NA Hertzler Ranch storm water system upgrades, lining west-side perc ponds, crusher operating area for Hertzler TSF construction, oil compressor building, LAD Pond expansion Operating Permit Minor Revision 04-001 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Apr-04 NA Modifications to Hertzler Ranch TSF and LAD Pond liner Operating Permit Minor Revision 04-002 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Sep-04 NA Soda ash silo installation, haul road on western edge of ESWRSF Operating Permit Minor Revision 04-003 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Dec-04 NA Temporary reduction in Nye TSF freeboard Operating Permit Minor Revision 05-001 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Oct-05 NA Advantex septic system upgrade, closure of MW- T3A Operating Permit Minor Revision 05-002 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Oct-05 NA Hertzler Stage 2 underdrain building, Hertzler Pump House expansion, admin building expansion Operating Permit Minor Revision 06-001 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Jan-07 NA Construction of West Fork Stillwater River breakout 232 Site Operating Permit and Type Status Permit Number Regulatory Agency Discharge Type Date Issued Renewal Date Description Operating Permit Minor Revision 06-002 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program May-06 NA New surface sand line to 5500W Portal, parking lot access road, new washbay, Loci Shop restroom addition Operating Permit Minor Revision 06-003 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program May-06 NA Concentrator storage building (east-side of concentrator) Operating Permit Minor Revision 07-001 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Jul-07 NA Emergency Response Building, west-side portal overflow containment Operating Permit Minor Revision 07-002 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Apr-09 NA Adjustment to flow monitoring requirement in Stillwater River Operating Permit Minor Revision 08-001 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Mar-08 NA Relocation of laydown to north-side of delivery road Operating Permit Minor Revision 08-002 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program May-08 NA Tailings water treatment (150gal per minute) and land application 233 Site Operating Permit and Type Status Permit Number Regulatory Agency Discharge Type Date Issued Renewal Date Description Operating Permit Minor Revision 08-003 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Aug-08 NA Reduction in Nye TSF freeboard (6ft to 5ft), employee survey discontinuance, upgrade of surface compressor line Operating Permit Minor Revision 08-004 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Nov-08 NA Construction of parking lot entrance cover, 5150W mine water system upgrades Operating Permit Minor Revision 09-001 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Apr-09 NA Land application of Hertzler TSF underdrain water, update Water Resources Monitoring Plan Operating Permit Minor Revision 09-002 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Feb-10 NA Increase final elevation of ESWRSF from 5050 ft to 5150 ft Operating Permit Minor Revision 09-003 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Sep-10 NA Hertzler TSF Stage 2 underdrain modification, relocate of Fire Water Pump House transformer, revisions to Water Resources Monitoring Plan 234 Site Operating Permit and Type Status Permit Number Regulatory Agency Discharge Type Date Issued Renewal Date Description Operating Permit Minor Revision 10-001 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Mar-10 NA Hertzler in-situ methanol treatment injection wells Operating Permit Minor Revision 10-002 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Jun-10 NA Contaminated soils building, Stillwater Mining Company-16 enclosure, level access pad construction near pump house power line Operating Permit Minor Revision 10-003 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Oct-10 NA Two 5400E vent raises near the 5400E Portal Operating Permit Minor Revision 10-004 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Nov-10 NA Concentrator expansion (ceramic mills), water treatment cell 6 building addition Operating Permit Minor Revision 11-001 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Apr-11 NA BASF pilot plant, oily dirt storage building Operating Permit Minor Revision 11-002 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Jun-11 NA Contaminated soils building, Stillwater Mining Company-16 enclosure, level access pad construction near pump house power line


235 Site Operating Permit and Type Status Permit Number Regulatory Agency Discharge Type Date Issued Renewal Date Description Operating Permit Minor Revision 11-003 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Jun-11 NA Raise bore hole from 4400 level to 5000W Portal for road Operating Permit Minor Revision 11-004 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Nov-11 NA Final design surface facilities for Blitz Project Operating Permit Minor Revision 12-001 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Apr-12 NA Relocate power line, buried electrical line and transformer, office trailer installations, ESWRSF in- situ methanol treatment Operating Permit Minor Revision 12-002 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Jun-12 NA HDPE pipe welding shop addition at Batch Plant, concrete installations Operating Permit Minor Revision 12-003 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Sep-12 NA Overhead process water line install, east-side storm water collection system, concrete pad Operating Permit Minor Revision 13-001 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Apr-13 NA Inspection interval change to Hertzler HDPE line (5-yr to 10-year), expansion of Advantex waste water treatment pods by 3 236 Site Operating Permit and Type Status Permit Number Regulatory Agency Discharge Type Date Issued Renewal Date Description Operating Permit Minor Revision 13-002 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Jul-13 NA New buried sandline from Hertzler Pump House to 5500W Portal, concrete retaining wall near propane tanks Operating Permit Minor Revision 13-003 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Dec-13 NA Process water booster pump station, concrete pad for oxygen/acetylene, methanol storage tank and containment at Upper BTS, concrete pad for hazardous waste storage locker Operating Permit Minor Revision 14-001 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Mar-14 NA LAD Pond expansion, Hertzler TSF Stage 3 construction plan Operating Permit Minor Revision 14-002 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Jul-14 NA Hertzler TSF Stage 3 construction plan modifications 237 Site Operating Permit and Type Status Permit Number Regulatory Agency Discharge Type Date Issued Renewal Date Description Operating Permit Minor Revision 14-003 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Nov-14 NA Faulty mobile equipment building, concrete pads on 5000W rail, burial of overhead power lines, lower BTS building expansion for booster pump, concrete barrier walls at surface crusher, concrete storm water conveyance, additional east-side injection well Operating Permit Minor Revision 15-001 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Sep-15 NA Concrete containment pad for biodiesel fuel tote storage Operating Permit Minor Revision 16-001 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Jan-16 NA Closure/Post-Closure monitoring locations (sites) Operating Permit Minor Revision 16-002 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Jun-16 NA ESWRSF lining system and water transfer system Operating Permit Minor Revision 16-003 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program May-15 NA Installation of inclinometers at the Nye and Hertzler TSFs Operating Permit Minor Revision 16-004 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Aug-16 NA Concrete sidewalk to new Blitz trailer 238 Site Operating Permit and Type Status Permit Number Regulatory Agency Discharge Type Date Issued Renewal Date Description Operating Permit Minor Revision 17-001 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Jun-17 5900W Portal Slope Stabilization and Ground Control, Concrete Pad and Containment; (East Side Rail Dump Expansion removed from MR 5/17/2017) Operating Permit Minor Revision 17-002 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Aug-17 Hertzler Ranch Perc Evaluation; Geotech work at West Fork (vent raise project); Geotech Evaluation upper Biological Treatment Cells; Add Admin Office Trailer Operating Permit Minor Revision 17-003 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Aug-17 Expansion of the existing east-side rail dump area with wind break for two new dump bays, a rail spur and concrete fuel containment area


239 Site Operating Permit and Type Status Permit Number Regulatory Agency Discharge Type Date Issued Renewal Date Description Operating Permit Minor Revision 17-004 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Nov-17 Installation of three supplemental monitoring wells at Hertzler Ranch near percolation ponds, expansion of the existing biological treatment system on the mine’s west site and installation of two water percolation ponds at the Hertzler Ranch site. Operating Permit Minor Revision 18-001 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Apr-18 Authorization to discharge to Hertzler Ranch Percolation Ponds Operating Permit Minor Revision 18-002 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Jun-18 BTS Expansion; Mix Tanks for Reagent Additions at Surface Clarifiers; Surface Haul Truck Traffic Beacons; Transformer and Concrete Containment at Hertzler LAD Pond 240 Site Operating Permit and Type Status Permit Number Regulatory Agency Discharge Type Date Issued Renewal Date Description Operating Permit Minor Revision 18-003 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Aug-18 Construction and operation of two ventilation raises from underground to surface (13.8 East and 13.8 West) Operating Permit Minor Revision 18-004 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Aug-18 New East-Side Portal and Revised Rail Dump Expansion Operating Permit Minor Revision 18-005 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Oct-18 Water Treatment Plant Screen/Filter House Operating Permit Minor Revision 19-001 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Mar-19 Geotechnical Site Investigations Stillwater Mine and Hertzler Ranch; Change Nye TSF Cap Geotextile use Operating Permit Minor Revision 19-002 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Jun-19 Temp Off-Site Cathedral Mountain Ranch Laydown and Construction Yard Operating Permit Minor Revision 19-003 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Jun-19 Administration Building Expansion, Increased Septic Tankage Operating Permit Minor Revision 19-004 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Jun-19 Concentrate Handling Systems Improvements 241 Site Operating Permit and Type Status Permit Number Regulatory Agency Discharge Type Date Issued Renewal Date Description Operating Permit Minor Revision 19-005 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Jun-19 Production Shaft Hydrogeo Test Dewatering Well Operating Permit Minor Revision 19-006 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Jan-20 Compressor Building Addition, Light Vehicle Safety Access Roads, Concentrator Reagent Building Relocation Operating Permit Minor Revision 20-001 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Feb-20 Modify the Stillwater Mine Concentrator 1) New Comminution Circuit Building, 2) New Electrical Substation, 3) Electrical pole re-routing Operating Permit Minor Revision 20-002 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program May-20 New Disc Filtration System and Building Operating Permit Minor Revision 20-003 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Jun-20 Minor Revision Acreage reconciliation: reconcile disturbed and permitted acreage in response to DEQ’s March 24 letter 242 Site Operating Permit and Type Status Permit Number Regulatory Agency Discharge Type Date Issued Renewal Date Description Operating Permit Minor Revision 20-004 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program Jul-20 Install two test wells and nested vibrating wire piezometers at Hertzler Ranch; in support of Stage 4/5 design Operating Permit Minor Revision 20-005 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program 20-Oct NA Power Line and Miscellaneous Concrete Addition Operating Permit Minor Revision 21-001 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program 21-Jul NA Increased thickness of the waste rock cap on the Nye Tailings Storage Facility Operating Permit Minor Revision 21-002 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program 21-Sep NA Installation of Test Wells Near the East Side Percolation Ponds Operating Permit Minor Revision 21-003 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program 21-Oct NA Processing Support Structures and Miscellaneous Concrete Addition Stillwater Mine Operating Permit Minor Revision 21-004 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program 21-Jul NA Installation of Test Wells and Nested Vibrating Wire Piezometers at Hertzler Ranch Operating Permit Minor Revision 21-005 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program 21-Nov NA Aquifer Test Discharge Plan


243 Site Operating Permit and Type Status Permit Number Regulatory Agency Discharge Type Date Issued Renewal Date Description Operating Permit Minor Revision 22-001 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program 22-May NA West Fork Breakout Operating Permit Minor Revision 22-002 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program 22-Jul NA Hertzler Ranch Corrective Actions for Groundwater Quality Operating Permit Minor Revision 22-003 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program 22-Aug NA Groundwater Corrective Actions. Installation of 13 monitoring wells and 3 methanol injection wells. Operating Permit Minor Revision 22-004 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program 22-Aug NA Pipeline Pond 3 to Hertzler LAD Pond: Additional Air Relief Valves Operating Permit Minor Revision 22-005 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program 22-Sep NA Flood Response: Bridge, Bypass Road, Pipelines, Access Road to 54E Operating Permit Minor Revision 22-006 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program 22-Dec NA Flood Recovery Efforts Operating Permit Minor Revision 23-001 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program 23-May NA Water Resources Monitoring Plan Operating Permit Minor Revision 23-002 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program 23-May NA Installation of Hertzler Conex Electrical Building and Corrective Actions for Groundwater Quality 244 Site Operating Permit and Type Status Permit Number Regulatory Agency Discharge Type Date Issued Renewal Date Description Operating Permit Minor Revision 23-003 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program 23-Jul NA Portal Heaters, Propane Tanks, and Blower Building Operating Permit Minor Revision 23-004 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program 23-Oct NA Stillwater River Road Relocation near Hertzler Ranch Operating Permit Minor Revision 23-005 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program 23-Nov NA Chemical Storage Building, Shotcrete Storage Building, and Septic Tank Conversion Operating Permit Minor Revision 23-006 Active 118 USFS CGNF/ DEQ Hard Rock Mining Program 24-Feb NA Streambank Layback Other Permits Treated Mine Water Discharge - Authorization to Discharge Under MPDES Active MT-0024716 DEQ Water Protection Bureau Groundwater or Surface Water Dec-15 Sep-23 Authorization to discharge treated mine water, under administrative extension until 9/2023 as permitting is completed 245 Site Operating Permit and Type Status Permit Number Regulatory Agency Discharge Type Date Issued Renewal Date Description MPDES Amendment In DEQ review MT-0024716 Groundwater or Surface Water Pending NA Request for additional time to complete improvements and additions (upgrades) to the water treatment systems, and once complete, to collect and evaluate post- stabilization system performance data Air Quality Permit – Preconstruction Permit Active 2459-20 Air Apr-22 NA Change propane usage to 5M gallons per rolling 12-month period Storm Water MPDES Permit Active MTR-000511 DEQ Water Protection Bureau Storm Water from site Oct-19 Jan-23 Multi-Sector General Permit for Storm Water Discharges Storm Water MPDES Permit Active MTR-000511 DEQ Water Protection Bureau Benbow Portal SWPPP; Addendum #2 Feb- 2023 Jan- 2028 Aug-19 AQ Burn Permit TW40 Not Active TW40 DEQ Hard Rock Mining Program Air Excavation 404 Permit – Hertzler Pipeline Active NA Army Corp of Engineers 246 Site Operating Permit and Type Status Permit Number Regulatory Agency Discharge Type Date Issued Renewal Date Description Potable Water System Authorization – Beartooth Ranch Active PWSID MT0003972 DEQ Public Water & Subdivision Bureau NA 1998 NA Potable Water System Authorization – Stillwater Mine Active PWSID MT0003587 DEQ Public Water & Subdivision Bureau NA 1986 NA Potable Water System Authorization – Stratton Ranch Not Active/Not Maintained PWSID MT0003588 DEQ Public Water & Subdivision Bureau NA NA Septic Drainfield – Septic System – Original system did not require permit Active NA DEQ Water Protection Bureau Groundwater 1986 NA Septic System – Onsite Wastewater Treatment System Active 05-Jun Stillwater County Groundwater Jan-06 NA Septic System Modification Authorization – Septic Treatment System with land application Active EQ-06-1122 (see MR05- 001) DEQ Water Protection Bureau and Environmental Management Bureau Groundwater Oct-05 NA Stillwater Mine Septic Drainfield – Septic System Modification Authorization – drainfield exp. Active ES94/B66 DEQ Water Protection Bureau NA Septic System – SVR Sewage Treatment System Permit Active 260 DEQ Water Protection Bureau NA Hazardous Waste Authorization/Classification Active MTD981552292 DEQ Waste and Underground Tank Management Bureau Jan-00 NA Conditionally Exempt Small Generator / Upgrade to Small Quantity if generation exceeds 100kg/month


247 Site Operating Permit and Type Status Permit Number Regulatory Agency Discharge Type Date Issued Renewal Date Description UIC Class V Injection – Authorization by Rule Active #MT5000-05134 USEPA Region 8 Groundwater Program Groundwater Nov-01 NA Mine recycle water UIC Class V Injection – Authorization by Rule – Large Capacity Septic System Active #MT5000-06454 USEPA Region 8 Groundwater Program Groundwater Mar-05 NA (Septic System) Change in operating methods and conditions triggers EPA review and approval Stillwater Mine UIC Class V Injection – Authorization by Rule – Hertzler Methanol Injection Well Active #MT50000-08681 USEPA Region 8 Groundwater Program Groundwater Dec-09 NA Methanol injection well at Hertzler UIC Class V Injection – Authorization by Rule – Amendment – Mine Site Methanol Injection Wells Active #MT50000-08681 USEPA Region 8 Groundwater Program Groundwater Jul-12 NA Methanol injection wells downgradient of ESWRSF (five) UIC Class V Injection – Authorization by Rule – Amendment – Mine Site Methanol Injection Wells Active #MT50000-08681 USEPA Region 8 Groundwater Program Groundwater Oct-14 NA Methanol injection wells downgradient of ESWRSF (one additional well) State-wide Exploration Permit Active 46 DEQ Hard Rock and Placer Exploration/USFS May-16 May-202 Renewed annually, via letter 4/6/2021 East Boulder Temporary Grazing or Livestock Use Permit Active NA USFS CGNF Aug-21 Feb-22 Renewed annually, renewed 2/28/2021; Ekwortzel/Kirch Agreement Encroachment Permit Active 2006-23 Stillwater County Encroachment Permit Active 2007-48 Stillwater County 248 Site Operating Permit and Type Status Permit Number Regulatory Agency Discharge Type Date Issued Renewal Date Description Encroachment Permit Active 2020-20 Jun-20 NA Road Encroachment Permit Application, culverts for pipeline to pass under existing road East Boulder USFS Special Use Permit – Stratton Ranch Road Active BEA407301 USFS CGNF Jan-16 Dec-16 Road Use Agreement USFS Special Use Permit – Delger Road Active BEA388 USFS CGNF 12-Aug Dec-21 Road Use Agreement; in renewal process, extended by mutual agreement Licenses East Boulder Nuclear Regulatory Commission – Materials License – Nuclear Density Gage Permit Active 25-26871-01 Nuclear Regulatory Commission Sep-14 Nov-23 Bureau of Alcohol Tobacco and Firearm – Explosives – Explosives Use and Storage Permit Active 9-MT-095-33-7B-90263 Bureau of Alcohol Tobacco and Firearms Feb-23 Radio Frequency Licenses – FCC Active 8610054645&8802398055 Federal Communications Commission Stratton Man Camp License Active T-6732 Agreements Road Use/Maintenance Agreement (FAS419 & FR846) Active NA USFS CGNF Mar-94 NA USFS Road Maintenance Agreement 249 Site Operating Permit and Type Status Permit Number Regulatory Agency Discharge Type Date Issued Renewal Date Description USFS Land Use Agreement Active AG-0355-B-15-5501 USFS CGNF Apr-15 Helibase Pad usage GNA Amendment Amended October 3, 2023 Active Oct-23 NA Good Neighbor Agreement Original Permits Plan of Operations (POO) Active 149 USFS CGNF/ DEQ Hard Rock Mining Program Feb-90 NA Plan of Operations Original (EIS) Record of Decision Active 149 USFS CGNF/ DEQ Hard Rock Mining Program Dec-92 NA Mine Permit Operating Permit Active 149 USFS CGNF/ DEQ Hard Rock Mining Program Mar-93 NA Operating Permit #00149 - Approved by ROD in 1993 following EIS Amendments Amendment 001 to Operating Permit (EA) Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 1999 NA Water Management Plan Amendment (EA) Amendments 002 & 003 to Operating Permit (EIS) Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2012 NA Revised Water Management Plan + Boe Ranch LAD (EIS) Minor Revisions Operating Permit Minor Revision 99-001 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 1999 NA Air Monitoring Site Operating Permit Minor Revision 00-001 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2000 NA Boe Ranch Pipeline Operating Permit Minor Revision 00-002 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2000 NA Tailings Pipeline Operating Permit Minor Revision 00-003 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2000 NA 6350 Explosives Bench laydown 250 Site Operating Permit and Type Status Permit Number Regulatory Agency Discharge Type Date Issued Renewal Date Description Operating Permit Minor Revision 01-001 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2001 NA Surface Crushing Facility Operating Permit Minor Revision 01-002 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2001 NA Slag Processing Operating Permit Minor Revision 01-003 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2001 Withdrawn Operating Permit Minor Revision 01-004 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2001 NA Temporary Buildings Operating Permit Minor Revision 04-001 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2004 NA Brownlee Vent Raise Operating Permit Minor Revision 04-002 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2004 NA Laydown Area 6 & Expansion of Soil Storage Operating Permit Minor Revision 04-003 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2004 NA LAD Area 6 Operating Permit Minor Revision 04-004 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2004 TSF – Detailed Design of Ongoing expansion Operating Permit Minor Revision 05-001 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2005 NA Warehouse Operating Permit Minor Revision 05-002 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2005 NA Water treatment improvements Operating Permit Minor Revision 06-001 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2006 NA TSF Wildlife Fence Operating Permit Minor Revision 06-002 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2006 NA Site Investigations Operating Permit Minor Revision 07-001 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2007 NA Event Pond Operating Permit Minor Revision 08-001 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2008 NA Native Borrow Excavation Operating Permit Minor Revision 08-002 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2008 NA New Oil Storage Building


251 Site Operating Permit and Type Status Permit Number Regulatory Agency Discharge Type Date Issued Renewal Date Description Operating Permit Minor Revision 09-001 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2009 NA EBMW-4 Replacement Well Operating Permit Minor Revision 09-002 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2009 NA Site Water Management Improvements Operating Permit Minor Revision 09-003 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2009 NA Reverse Osmosis Unit Operating Permit Minor Revision 09-004 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2009 NA In Situ Denitrification System Operating Permit Minor Revision 10-001 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2010 NA Drilling Investigation Operating Permit Minor Revision 10-002 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2010 NA Drilling Investigation Phase 2 Operating Permit Minor Revision 10-003 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2010 NA Surface Rail Improvements Operating Permit Minor Revision 10-004 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2010 NA Expansion of In-Situ Denitrification Operating Permit Minor Revision 11-001 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2011 NA Groundwater Capture System Operating Permit Minor Revision 12-001 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2012 NA Graham and Simpson Ventilation Raises Operating Permit Minor Revision 12-002 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2012 NA Truck Fall Arrest System Operating Permit Minor Revision 13-001 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2013 NA Modification to Simpson Creek Vent Raise Operating Permit Minor Revision 13-002 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2013 NA TSF Nitrogen Reduction Operating Permit Minor Revision 13-003 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2013 NA Used Oil Building Addition 252 Site Operating Permit and Type Status Permit Number Regulatory Agency Discharge Type Date Issued Renewal Date Description Operating Permit Minor Revision 13-004 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2013 NA GNA borehole drilling Operating Permit Minor Revision 14-001 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2014 NA Perc Pond Event Pond Modifications/Expansion Operating Permit Minor Revision 14-002 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2014 NA Borrow pit access road intersection realignments (2) Operating Permit Minor Revision 14-003 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2014 NA Two GNA Wells (EBMW- 12 and EBMW-13) Operating Permit Minor Revision 14-004 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2014 NA Stage 3 TSF Slope Liner Design Change Operating Permit Minor Revision 15-001 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2015 NA Stage 3 TSF Slope Cover Final Design Operating Permit Minor Revision 15-002 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2015 NA New BO Parts Building Operating Permit Minor Revision 15-003 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2015 NA Geotechnical Test Holes Operating Permit Minor Revision 16-001 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2016 NA Water Resources Monitoring Plan Operating Permit Minor Revision 16-002 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2016 NA TSF Inclinometers Operating Permit Minor Revision 16-003 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2016 NA Revised Biological Monitoring Plan Operating Permit Minor Revision MR17-001 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2017 NA Groundwater Mixing Zone Operating Permit Minor Revision MR17-002 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2017 NA Site Security Gates 253 Site Operating Permit and Type Status Permit Number Regulatory Agency Discharge Type Date Issued Renewal Date Description Operating Permit Minor Revision MR18-001 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2018 NA Water Resources Monitoring Plan – no new disturbance Operating Permit Minor Revision MR18-002 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2018 NA Biological Monitoring Plan – no new disturbance Operating Permit Minor Revision MR18-003 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2018 NA Thickener and Portal Collection System Operating Permit Minor Revision MR18-004 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2018 NA Yates Deep Injection Test Well Operating Permit Minor Revision MR18-005 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2018 NA Geotechnical Drilling and Inclinometer East Boulder Operating Permit Minor Revision MR19-001 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2019 NA Monitoring Well EBMW- 12A Operating Permit Minor Revision MR19-002 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2019 NA Area 51 Borrow Design Changes - Operating Permit Minor Revision MR19-003 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2019 NA WTP Disk Filter System Operating Permit Minor Revision MR19-004 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2019 NA Concentrate Load-out Operating Permit Minor Revision MR19-005 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2019 NA Dry Fork Monitoring Wells Operating Permit Minor Revision MR20-001 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2020 NA Boe Ranch Deep Well Injection BRIW-1 Operating Permit Minor Revision MR20-002 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2021 NA Power Line Relocation – Southern Route 16.12 acres, 60 ft ROW Operating Permit Minor Revision MR20-003 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2020 NA Frog Pond Emergency Shelter 254 Site Operating Permit and Type Status Permit Number Regulatory Agency Discharge Type Date Issued Renewal Date Description Operating Permit Minor Revision MR20-004 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2020 NA Updates the Biological Monitoring Plan Operating Permit Minor Revision MR20-005 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2020 NA Concrete Aprons and Security Gate Operating Permit Minor Revision MR20-006 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2020 NA Bridge Geotechnical Drilling Operating Permit Minor Revision MR21-001 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2021 NA Construct Acid Storage Building/Injection Well Operating Permit Minor Revision MR21-002 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2021 NA Stage 6 Monitoring Well Relocation Operating Permit Minor Revision MR21-003 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2021 NA Amendment 004 Dry Fork WRSA baseline monitoring wells Operating Permit Minor Revision MR21-004 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2021 NA Amendment 004 Portal Pump/Vault System and Mill Fuel Tank Relocation Operating Permit Minor Revision MR22-001 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2022 NA Main Fuel Containment Expansion Operating Permit Minor Revision MR22-002 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2022 NA Dry Fork Haul Road Geotechnical Operating Permit Minor Revision MR22-003 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2022 NA Portal Heater and Propane Distribution Upgrade Operating Permit Minor Revision MR22-004 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2022 NA Warehouse Septic


255 Site Operating Permit and Type Status Permit Number Regulatory Agency Discharge Type Date Issued Renewal Date Description Operating Permit Minor Revision MR22-005 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2022 NA Tree Cutting Power Line Operating Permit Minor Revision MR22-006 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2022 NA GW Monitoring Well EBMW-21 East Boulder Operating Permit Minor Revision MR22-007 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2022 NA Stage 4 and 5 Overflow Channel Operating Permit Minor Revision MR22-008 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2022 NA Sidewalk and Cattle Guards Operating Permit Minor Revision MR23-001 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2023 NA A1 and A2 Stockpile Relocation Operating Permit Minor Revision MR23-002 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2023 NA BVR Heat Exchanger East Boulder Operating Permit Minor Revision MR23-003 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2023 NA EBMW-3A and 6A Operating Permit Minor Revision MR23-004 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2023 NA Concrete Allowance Operating Permit Minor Revision MR23-005 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2023 NA Concrete Allowance Operating Permit Minor Revision MR23-006 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2023 NA Water Resources Monitoring Operating Permit Minor Revision MR23-007 Active 149 USFS CGNF/ DEQ Hard Rock Mining Program 2023 NA BVR Access Road Relocation Other Permits 256 Site Operating Permit and Type Status Permit Number Regulatory Agency Discharge Type Date Issued Renewal Date Description Metallurgical Complex Authorization to Discharge Under MPDES Active MT-0026808 DEQ Water Protection Bureau Groundwater or Surface Water Nov-15 Oct-20 Application for Renewal was completed & submitted in Jan 05; DEQ administratively extended the permit until the application was processed and a new permit issued. Authorization to Discharge Under MPDES Active MT-0026808 DEQ Water Protection Bureau Groundwater or Surface Water Aug-20 Oct-20 Mixing Zone; DEQ administratively extended the permit until the application is processed and a new permit issued. Storm Water MPDES Permit Active MTR-000503 DEQ Water Protection Bureau Storm Water from site Feb-18 Jan-23 Multi-Sector General Permit for Storm Water Discharges Air Quality Permit Active MAQP 2563-05 DEQ Air Resources Bureau Air Jul-18 NA Air Permit update to increase production Public Water Supply Amendment 1 Active MT-0003894 DEQ Public Water & Subdivision Bureau Jan-06 NA No expiration date changes in system trigger permit amendment. Warehouse and Dry expansion Septic Tank and Drain field – Septic Drain field Active EQ98/B50 DEQ Water Protection Bureau Groundwater Nov-98 NA State of Montana 257 Site Operating Permit and Type Status Permit Number Regulatory Agency Discharge Type Date Issued Renewal Date Description Septic Tank and Sewage Treatment Plant – Septic Drain field Active 382 Sweet Grass County Groundwater Jan-99 NA Sweet Grass County Permit Septic Tank and Drain field – Amendment – Septic Drain field Active EQ06-3314 DEQ Water Protection Bureau Groundwater Jan-06 NA Warehouse and Dry expansion Hazardous Waste Authorization/Classification Active MTR-000007823 DEQ Waste Management Bureau Jan-00 NA Conditionally Exempt Small Generator / Upgrade to Small Quantity if generation exceeds 100kg/month UIC Class V Injection – Authorization by Rule Active #MT5000-05150 USEPA Region 8 Groundwater Program Groundwater Apr-02 NA Underground Mine Water UIC Class V Injection – Authorization by Rule – Amendment – Underground Mine Water Active #MT5000-05150 USEPA Region 8 Groundwater Program Groundwater Jun-02 NA (Underground Water) Change in operating methods and conditions triggers EPA review and approval UIC Class V Injection – Authorization by Rule – Septic System Active #MT50000-06439 USEPA Region 8 Groundwater Program Groundwater Mar-05 NA (Septic System) Change in operating methods and conditions triggers EPA review and approval UIC Class V Injection – Authorization by Rule – Methanol Injection Active #MT50000-008511 USEPA Region 8 Groundwater Program Groundwater Sep-09 NA Methanol Injection 258 Site Operating Permit and Type Status Permit Number Regulatory Agency Discharge Type Date Issued Renewal Date Description UIC Class V Injection – Authorization by Rule – Amendment – Methanol Injection Active #MT50000-008511 USEPA Region 8 Groundwater Program Groundwater Jan-11 NA Injection into additional 3 wells UIC Class V Injection – Authorization by Rule – Amendment – Underground Mine Water Active #MT50000-11713 USEPA Region 8 Groundwater Program Groundwater Sep-18 NA Disposal of treated adit water from the underground mine. Road Agreement Active NA USFS Fire Management Division CGNF Road Right of Way Active NA USFS Fire Management Division CGNF State Trade Waste Burn Permit – Air Quality Burn Permit Active TW459 DEQ Air Resources Bureau Air Sep-19 Sep-22 Renew Annually Forest Service Burn Permit – Burn Permit Active NA USFS Fire Management Division CGNF Air As Needed As Needed Required for individual burns between May 1 and October 15; apply as needed Licenses State-wide Exploration License Active 46 DEQ Hard Rock and Placer Exploration/USFS May-20 May-22 Renewed Annually Nuclear Regulatory Commission – Materials License – Nuclear Density Gage Permit Active 25-26871-01 Nuclear Regulatory Commission Sep-14 Nov-23 Bureau of Alcohol Tobacco and Firearm – Explosives Active 9-MT-095-33-7B-90263 Bureau of Alcohol Tobacco and Firearms Feb-23 Agreements


259 Site Operating Permit and Type Status Permit Number Regulatory Agency Discharge Type Date Issued Renewal Date Description FDR 205 and FDR 6644 Road Maintenance Agreement Active USFS CGNF/DEQ Hard Rock Mining Program Aug-96 NA USFS Road Maintenance Agreement Snotel Active No. 65-0325-14-001 NRCS–- National Resource Conservation Service Jan-17 USDA–- Annual Renewal, funded by SSW through 2017 State Lands Lease Active DNRC Trust Land Management Division Mar-16 Mar-23 GNA 2009 Amendment Active Jan-09 NA Good Neighbor Agreement Boe Ranch Grazing Lease – Private party lease Active Mar-16 Mar-17 Original Permits Air Quality Permit – Air Quality Permit Active 2635-17 DEQ Air Resources Bureau Air Oct-12 NA Covers Smelter, BMR, and Laboratory Storm Water MPDES Permit – Storm Water Discharge Permit Active MTR-000469 DEQ Water Protection Bureau Storm Water from site Dec-13 Jan-23 Multi-Sector General Permit for Storm Water Discharges 260 Requirements for Environmental Monitoring, Closure and Post Closure, and Management Plans 17.2.5.1 Stillwater Mine and Hertzler Ranch Facilities Operational management, reclamation and monitoring of wastes and reclamation of waste management facilities are addressed in the current Consolidated Operations and Reclamation Plan as well as the Operating Permit 00118. In addition, waste management facilities are described in Section 15.1. Mine waste solids are managed in the TSFs, which include the Hertzler TSF and the Nye TSF. In addition, waste rock at the Stillwater Mine is managed in waste rock storage areas, which include the East Side Waste Rock Storage Facility (ESWRSF) and the Benbow Portal waste rock storage area which is currently inactive. Mine liquid wastes at Stillwater Mine include mine adit water, process water, waste rock storage area infiltration water and potable water supplies. Water collected underground (natural groundwater, recycled mining water, and mine decant water from the mine backfill slurry) is pumped to the surface where it undergoes settling in clarifiers and may be stored in surface recycle water storage tanks. Recycle water is returned for reuse underground in the mining process. Excess water not recycled for mining is routed to the West-Side Biological Treatment System/Moving Bed Bioreactor (BTS/MBBR) prior to disposal. Potable water is supplied by two water wells, namely West Well 1 (PW-W) and East Well 2 (PW-E). Water from infiltration of meteoric water through the ESWRSF is managed through a nitrate capture system (NCS) that is constructed of (from top to bottom) a 12-inch-thick drain-rock layer, a geo- composite drainage layer, and textured both sides 60-mil to 80-mil high-density polyethylene (HDPE) geomembrane liner. Nitrogen-containing meteoric waters intercepted by the drain layer and membrane liner are conveyed to an exterior collection pond. The NCS water may be routed for recycle use underground or transferred to the BTS/MBBR. Smelter slag is processed at the Stillwater Concentrator on a campaign basis. Slag is hauled in containers separate from the concentrate and stockpiled near the 5000E Portal. When sufficient slag (approximately 2 500 tons) accumulates, RoM ore processing stops thus paving the way for the processing of slag, usually on a 24-hour campaign. Smelter slag is treated by the same beneficiation process that is used for ore. Spent material from the slag that is reprocessed through the concentrator reports to the lined tailings impoundment or as backfill in the underground mine. The volume of reprocessed spent material has historically been an insignificant percentage of the total material processed at the Stillwater concentrator. Smelter slag may also be processed at the East Boulder Concentrator under the EBPO/OP MR01-001. Operational monitoring programs include air quality, surface water, groundwater, injection wells, adit water, storm water, biological conditions, tailings storage facility monitoring, and monitoring of water treatment systems. This monitoring is documented in actionable reports identified in Table 53. 261 Table 53: Stillwater Mine Operations Actionable Reportable Documents Required Submittals -Operations Required Basis Frequency Format Due Date(1) Air Resources: Air Quality Monitoring Report Montana Air Quality Permit No. OP2459-11 Semi- Annual Electronic 15-Feb Air Quality Emissions Inventory Report Montana Air Quality Permit No. MAQP No. 2459-18 Annual Electronic 15-Feb Water Quality and Quantity: MPDES Discharge Monitoring Reporting Montana Pollutant Discharge Elimination System Permit (MPDES) No. MT0024716 Monthly Electronic DMR 28th of following month Quarterly 28th of month following end of Q1, Q2, Q3, and Q4 Stillwater Mine MPDES Storm Water Report Multi-Sector General Permit for Storm Water Discharges Associated with Industrial Activity No. MTR000511 Quarterly Electronic DMR 28th of month following end of Q1, Q2, Q3, and Q4 Water Resources Monitoring Report 1992 Final EIS and ROD Stillwater Expansion (2000 Tons Per Day) 2023 Water Resources Monitoring Plan (WRMP) Annual Electronic 30-Jun Water Quality and Quantity; Wildlife/Aquatic Resources: Biological Monitoring Report 1992 Final EIS and ROD Stillwater Expansion (2000 Tons per Day) Biological Monitoring Plan Annual Electronic 31-May Chlorophyll-a Periphyton and Macroinvertebrates 2nd year Electronic 31-May (respective years only) Geochemistry: Adit Water Quality Report in Annual Water Resources Monitoring Report Operating Permit (OP) No. 00118 2023 Water Resources Monitoring Plan (WRMP) Annual Electronic 30-Jun Waste Rock and Tailings Characterization in OP Annual Progress Report 1992 Final EIS and ROD Stillwater Expansion (2000 Tons per Day) Annual Electronic 28-Feb Mining Plan: OP Annual Progress Report OP No. 00118 Annual Electronic Electronic Submitted by Engineer of Record 120 days after conducting annual Tailings Storage Facility (TSF) Tailings Operations, Maintenance and Surveillance Inspection Report 82-4-336 MCA 2014 2012 Final EIS Revised Water Management Plan 2012 ROD Revised Water Management Plan Annual Nye and Hertzler TSF Supernatant Volume and Tailings Grade Nye and Hertzler Tailing Storage Facility Structural Integrity and Function Annual Nye and Hertzler Tailings density 5-year Hertzler TSF Underdrain in Annual Water Resources Monitoring Report Annual 30-Jun Consolidated Operations Reclamation Plan Annual 01-Jul Federal Reporting Requirements: Injection Well Monitoring Stillwater Mine Remediation Wells Authorization by rule Electronic Upon changes to injection program and as requested by EPA Toxic Release Inventory Report U.S. Environmental Protection Agency (EPA) Emergency Annual Electronic 01-Jul 262 Required Submittals -Operations Required Basis Frequency Format Due Date(1) Planning and Community Right to Know Act Note (1) Q refers to quarter and Q1 refers to first quarter, etc. Note: DEQ= MT Department of Environmental Quality; MAQP=MT Air Quality Permit; AQB=Air Quality Bureau; WPB=Water Protection Bureau; EIS= Environmental Impact Statement; ROD=Record of Decision; DMR=Discharge Monitoring Report; MCA=Montana Code Annotated; EIS=Environmental Impact Statement; ROD=Record of Decision; TSF=Tailings Storage Facility Water management and treatment methods include water recycling in the mining process, clarification, biological treatment for nitrate, filtration, stormwater management, and discharge to the ground surface by land application disposal or percolation in infiltration ponds. Water quality impacts that can be attributed to Stillwater Mine operations from 1981 to 2023 are limited to increased nitrate and total dissolved solids levels in groundwater beneath the Stillwater Mine, Hertzler Ranch site, and Benbow waste rock storage area. As a result of in situ groundwater denitrification, increases in iron, nickel, and manganese have been detected in a couple of downgradient monitoring wells from changing redox conditions. The conditions are corrected when denitrifications activities are discontinued. No other constituents of concern have been identified during water quality monitoring and through numerous environmental reviews and analyses. Groundwater monitoring at the Stillwater Mine and associated facilities is performed per the Water Resource Management Plan as a condition of the Stillwater Mine Plan of Operations as documented in the Consolidated Operations and Reclamation Plan. The Water Resource Management Plan contains a comprehensive listing of all required water quality monitoring for the Stillwater Mine, Stratton Ranch and Hertzler Ranch. In total, the Water Resource Management Plan, describes requirements for groundwater monitoring at 50 sites, which include 32 monitoring wells at the mine site, 17 monitoring wells at the Hertzler Ranch and three monitoring wells at the Stratton Ranch. Closure monitoring is documented in actionable reports identified in Table 54 while post-closure monitoring is documented in actionable reports in Table 55. The Stillwater Mine Reclamation Plan incorporates the measures analysed and approved under the 2012 Record of Decision (DEQ and USFS, 2012a). The reclamation plan for the Benbow Portal was developed as a separate document but is now included in the annual update to the Consolidated Operations and Reclamation Plan. All surface disturbances within the permit boundary will be reclaimed, where required. Underground mine closure, closure of facilities at Stillwater Mine and Hertzler Ranch, and water management at closure are described in the plan. Final reclamation will take place after mine operations have ceased for portions not otherwise reclaimed concurrently during operations. Table 54: Stillwater Mine Closure Actionable Reportable Documents Required Reporting—Closure (Years 1-3) Requirement Basis Frequency Format Due Date Water Quality and Quantity: Water Resources Monitoring Report Groundwater and Surface Water monitoring occurs seasonally (three times per year) 2012 ROD; OP 00118 WRMP Annual Electronic Year 1: 60 days past Q4 of closure Years 2 and 3: anniversary of initial report Adit Water Monitoring Monitoring occurs monthly until discharged underground 2012 ROD Annual Electronic


263 Required Reporting—Closure (Years 1-3) Requirement Basis Frequency Format Due Date Hertzler TSF Underdrain, Hertzler Ranch TSF Cover Seepage, and Stillwater TSF Cover Seepage Monitoring occurs seasonally until quality stabilizes 2012 ROD Annual Electronic Shaft Water Quality and Level/Elevation Monitoring Monitoring occurs seasonally for quality and level until stabilization, then annual frequency 2012 ROD Annual Electronic Hertzler Ranch Land Application Disposal System Annual monitoring for salts load from land application system during closure 2012 ROD Annual Electronic Reclamation Plan; Geotechnical and Stability: Tailings Storage Facility (TSF): Stillwater TSF Structural Integrity and Function Annual inspection by Engineer of Record, maintenance as needed 2012 ROD 2012 Final EIS Revised Water Management Plan Annual Electronic Year 1: 60 days past Q4 of closure Years 2 and 3: anniversary of initial report Stillwater TSF Seepage Outlet Structure and Shaft Trout Stream Channel Annual inspection, maintenance as needed Hertzler Ranch TSF Structural Integrity and Function Annual inspection, maintenance as needed Annual Electronic Reclamation Plan; Geotechnical and Stability: Hertzler Seepage Outlet Structure and Discharge Channel to LAD Pond Annual inspection, maintenance as needed 2012 Final EIS 2012 ROD Revised Water Management Plan Annual Electronic Year 1: 60 days past Q4 of closure Years 2 and 3: anniversary of initial report Stillwater Mine Storm Water Channels Annual inspection, maintenance as needed Annual Electronic Table 55: Stillwater Mine Post Closure Actionable Reportable Documents Required Reporting—Post Closure (Years 4-8) Requirement Basis Frequency Format Due Date Reclamation Plan; Water Quality and Quantity: Water Monitoring Report Groundwater and Surface Water monitoring occurs seasonally (three times per year) 2012 ROD Revised Water Management Plan; OP 00118 WRMP Annual Electronic Years 4 through 8: annual anniversary of initial closure report Shaft Water Quality and Level/Elevation Monitoring occurs seasonally for quality and level until stabilization, then annually until it discharges Annual Hard Copy Report Years 4 through 8: annual anniversary of initial closure report Reclamation Plan; Geotechnical and Stability: Hertzler and Stillwater TSF Structural Integrity and Function; Annual visual monitoring Years 4 and 5 2012 Final EIS and ROD Annual Hard Copy Report Years 4 through 8: annual anniversary of initial closure report Visual monitoring every 5 years from Year 5 until final bond release 5-Year Electronic Fifth-year anniversaries of Year 5 closure report Stillwater TSF Seepage Outlet Structure and Shaft Discharge Trout Stream, Hertzler TSF Cover Seepage Discharge Channel, Storm Water Channel Monitoring annually Years 4 – 8 Annual Electronic Years 4 through 8: annual anniversary of initial closure report Monitoring every 5 years from Year 5 until final bond release 5-Year Electronic Fifth-year anniversaries of Year 5 closure report Site Maintenance Monitoring: 264 Required Reporting—Post Closure (Years 4-8) Requirement Basis Frequency Format Due Date Function of facilities Ponds (percolation and Hertzler LAD storage) Storm water ditches and sediment basins TSF seepage and Shaft outlet channels TSF covers and underdrain outlet structures 2012 Final EIS Revised Water Management Plan 2012 FMEA Annual Electronic Years 4 through 8: annual anniversary of initial closure report Abandon/Close Monitoring Wells Abandonment anticipated to be in Year 9 Year 9: anniversary of initial closure report Vent raise replacement 2012 USFS 2012 FMEA Year 63 Note: FMEA=Failure Modes and Effects Analysis; ROD=Record of Decision; WRMP=Water Resources Monitoring Plan Concurrent reclamation has occurred since the start of operations in 1986. At the time of mine closure and facilities reclamation, all surface facilities will be decommissioned, all structures will be disassembled and removed from the site, and the land reclaimed consistent with the approved post-mine land use. Roads that will remain will include the main access road to the reclaimed portals, tailings storage facilities, water conveyance structures, and water monitoring sites to allow for long-term monitoring and maintenance. These roads will be reclaimed when long-term monitoring and maintenance activities cease. The Qualified Persons conclude that adequate volumes of soil materials are available for replacement of the required soil cover on all disturbances. Furthermore, reclamation should meet the State of Montana provisions and requirements under the Montana Metal Mine Reclamation Act (MCA 82-4-336). The Stillwater Mine Closure and Reclamation Plan is also intended to meet the USFS requirements governing mineral development (36 CFR 228.8), and reclamation requirements under the Federal Seed Act (7 U.S.C., Section 1551-1610) and current USFS seeding guidelines. 17.2.5.2 East Boulder Mine East Boulder Mine consists of the underground mine and surface processing, waste rock and tailings storage facilities. The Consolidated Operations and Reclamation Plan describes water management of both underground mine water, supernatant water from the tailings storage facility, and basin and embankment underdrain water. Operational management, reclamation and monitoring of wastes and reclamation of waste management facilities are addressed in the current Consolidated Operations and Reclamation Plan for East Boulder Mine. East Boulder Mine has several plans including those for water resource and biological monitoring and resource protection. Operational monitoring programs include air quality, surface water, groundwater, injection wells, adit water, storm water, biological conditions, TSF, and water treatment systems. This monitoring is documented in actionable reports identified in Table 56. Waste management facilities are described in Section 15.2. Mine waste solids are managed in the East Boulder TSF. Waste rock from the underground mine is currently used in construction of the TSF embankments. The finest fraction of the tailings is pumped to the lined tailings facility. Currently, Stages 5 and 6 are being constructed. Supernatant water from the TSF is recycled in a closed loop system with the mill. The TSF basin capture water is pumped to either the TSF supernatant pond or the water recycle pond. The embankment underdrain capture water is pumped to the TSF supernatant pond. 265 Water collected underground (natural groundwater, recycled mining water, and mine decant water from the slurry of mine backfill) is discharged from the mine adit, collected, treated in the treatment plant, and then returned for reuse underground in the mining process or discharged via the approved MPDES Permit. Water management and treatment methods include water recycling in the mining process, biological treatment for nitrate, stormwater management, and discharge to the groundwater by percolation in infiltration ponds. East Boulder Mine recently received approval to dispose of water in a deep injection well on Boe Ranch, although this system has not yet been placed into service. The Water Resources Monitoring Plan, updated in August 2021, is a reference document for all water quality monitoring for the Plan of Operations, the Operating Permit No. 00149 and the MPDES Permit MT0026808. The plan outlines the approved monitoring locations, schedule, list of parameters for analysis, and methods for sampling of surface water, mine water, and groundwater at East Boulder Mine. Monitoring requirements for the Boe Ranch LAD facility are included in the Water Resources Monitoring Plan and include sampling of springs and groundwater and surface water locations as required by the EIS and the Record of Decision but will only become active if the land application disposal facility is constructed. Table 56: East Boulder Mine Operations Actionable Reportable Documents Required Submittals - Operations Required Basis Frequency Format Due Date(1) Air Resources: Air Quality Monitoring Report Montana Air Quality Permit No. 2563-07 Annual Hard Copy 15-Feb Air Quality Emissions Inventory Report Montana Air Quality Permit No. 2563-07 Annual Electronic 15-Feb Water Quality and Quantity: MPDES Discharge Monitoring Reporting Montana Pollutant Discharge Elimination System Permit (MPDES) No. MT0026808 Monthly Electronic DMR 28th of following month Quarterly 28th of month following end of Q1, Q2, Q3, and Q4 Annual 28th of month following end of Q4 MPDES Storm Water Report Multi-Sector General Permit for Storm Water Discharges Associated with Industrial Activity No. MTR000503 Quarterly Electronic DMR 28th of month following end of Q1, Q2, Q3, and Q4 Water Monitoring Report 1992 Final EIS and ROD Water Resources Monitoring Plan (WRMP) Quarterly with Annual Summary Hard Copy 60 days past end of Q1, Q2, Q3, and Q4 and Annual Summary February Water Quality and Quantity; Wildlife/Aquatic Resources: Biological Monitoring Report Biological Monitoring Plan Annual Hard Copy 30-April Chlorophyll-a Periphyton and Macroinvertebrates 3rd-year Hard Copy 30-April (respective years only) Geochemistry: 266 Required Submittals - Operations Required Basis Frequency Format Due Date(1) Adit Water Quality Report Quarterly Monitoring Operating Permit No. 00149 Quarterly with Annual Summary Hard Copy 60 days past end of Q1, Q2, Q3, and Q4 Waste Rock and Tailings Characterization 1992 Final EIS and ROD Quarterly with Annual Summary Hard Copy 60 days past end of Q1, Q2, Q3, and Q4 and Annual Summary February Mining Plan: MMRA Operating Permit Annual Report Operating Permit No. 00149 Annual Hard Copy 26-May Tailings Storage Facility (TSF) Tailings Operations, Maintenance and Surveillance Inspection Report 82-4-336 MCA 2014 2012 Final EIS Revised Water Management Plan 2012 ROD Revised Water Management Plan Annual Tailings Supernatant Volume and Tailings Grade Impoundment Structural Integrity and Function Annual Tailings Density 5-year Tailings Impoundment Underdrain Monitoring occurs quarterly Annual 30-Jun Consolidated Operations Reclamation Plan Annual 01-Jul Federal Reporting Requirements: Toxic Release Inventory Report U.S. Environmental Protection Agency (EPA) Emergency Planning and Community Right to Know Act Annual Electronic 01-Jul Federal Reporting Requirements: UIC Permits water injection/disposal U.S. Environmental Protection Agency (EPA) Annual Electronic Upon changes to injection program and as requested by EPA Federal Reporting Requirements: Injection Well Monitoring Remediation Wells Authorization by Rule U.S. Environmental Protection Agency (EPA) Electronic Upon changes to injection program and as requested by EPA (1) Q refers to quarter, Q1 refers to first quarter, etc. Note: DEQ= MT Department of Environmental Quality; MAQP=MT Air Quality Permit; AQB=Air Quality Bureau; WPB=Water Protection Bureau; EIS= Environmental Impact Statement; ROD=Record of Decision; DMR=Discharge Monitoring Report; MCA=Montana Code Annotated; EIS=Environmental Impact Statement; ROD=Record of Decision; TSF=Tailings Storage Facility The Qualified Persons can confirm that closure monitoring is documented in actionable reports identified in Table 57 while post-closure monitoring is documented in actionable reports listed in Table 58. All surface disturbances within the permit boundary will be reclaimed, where required. Underground mine closure, closure of facilities, and water management at closure are described in the Consolidated Operations and Reclamation Plan, which addresses closure and post-closure monitoring. Final reclamation will take place after mine operations have ceased for portions not otherwise reclaimed concurrently during operations. Table 57: East Boulder Mine Closure Actionable Reportable Documents Required Reporting—Closure (Years 1-3) Requirement Basis Frequency Format Due Date Water Quality and Quantity: Water Resources Monitoring Report Monitoring occurs quarterly 2012 ROD; Revised Water Management Plan; Annual Hard Copy Year 1: 60 days past Q4 of closure


267 Required Reporting—Closure (Years 1-3) Requirement Basis Frequency Format Due Date Operating Permit 00149 Surface and Groundwater Monitoring Plan Years 2 and 3: annual anniversary of initial report Adit Water Monitoring Monitoring occurs tri-annually: spring, summer, fall 2012 ROD; Revised Water Management Plan Annual Hard Copy Reclamation Plan; Geotechnical and Stability: Tailings Storage Facility: Impoundment Underdrain Monitoring occurs quarterly 2012 ROD 2012 Final EIS Revised Water Management Plan Annual Hard Copy Year 1: 60 days past Q4 of closure Years 2 and 3: annual anniversary of initial report Tailings Impoundment Cover Seepage Monitoring occurs quarterly Tailings Density, Grade, Supernatant Volume Impoundment Structural Integrity and Function Visual monitoring occurs annually Annual Hard Copy Table 58: East Boulder Mine Post Closure Actionable Reportable Documents Required Reporting—Post Closure (Years 4-8) Requirement Basis Frequency Format Due Date Reclamation Plan; Water Quality and Quantity: Water Monitoring Report Monitoring occurs quarterly 2012 ROD; Revised Water Management Plan; Operating Permit 00149 Surface and Groundwater Monitoring Plan Annual Hard Copy Report Years 4 through 8: annual anniversary of initial closure report Adit Water Monitoring Monitoring occurs bi-annually 2012 ROD; Revised Water Management Plan Annual Hard Copy Report Years 4 through 8: annual anniversary of initial closure report Reclamation Plan; Geotechnical and Stability: Tailings Storage Facility Impoundment Structural Integrity and Function. Annual visual monitoring Years 4 and 5 2012 Final EIS and ROD; Revised Water Management Plan Annual Hard Copy Report Years 4 through 8: annual anniversary of initial closure report Tailings Storage Facility Visual monitoring until final bond release 5-Year Hard Copy Report Fifth-year anniversaries of Year 5 closure report Tailings Storage Facility Seepage Outlet Structure, Cover Seepage Discharge Channel, Storm Water Channel Monitoring annually Years 4 – 8 Annual Hard Copy Report Years 4 through 8: annual anniversary of initial closure report Tailings Storage Facility Monitoring every 5 years from Year 5 until final bond release 5-Year Hard Copy Report Fifth-year anniversaries of Year 8 closure report Site Maintenance Monitoring: Function of facilities Ponds Storm water ditches and basins Tailings Storage Facility seepage outlet channels 2012 Final EIS Revised Water Management Plan 2012 FMEA Annual Hard Copy Report Years 4 through 8: annual anniversary of initial closure report 268 Required Reporting—Post Closure (Years 4-8) Requirement Basis Frequency Format Due Date Tailings Storage Facility cover and underdrain outlet structure Vent raise replacement 2012 USFS Report Year 63 from closure Note: FMEA=Failure Modes and Effects Analysis; ROD=Record of Decision; WRMP=Water Resources Monitoring Plan 17.2.5.3 Columbus Metallurgical Complex Waste management facilities at the Columbus Metallurgical Complex include temporary gypsum and smelter slag storage and storm water management. Air emissions are managed and monitored per the 2019 air permit requirements and include bag house collection of particulates and SO2 scrubbing systems. Air monitoring includes measurement of opacity, particulate emissions (PM10 and PM2.5), CO, VOC and SO2 emissions, and effluent flow rates. The air permit was updated in 2019 to encompass planned increases in production and refining. SMC (Sibanye-Stillwater) was given approval for the processing of smelter slag at Stillwater and East Boulder Mines to recover additional precious metals. Slag from the smelter is trucked to the mines daily for batch processing. Slag is also crushed in campaigns and used as slag pit liner material. A quarterly sample is collected and analysed for leachability (TCLP); testing to date confirms the slag passes TCLP criteria as non-hazardous. The slag is temporarily stored on the East Property located southeast of the smelter and in the slag bunkers located north of the smelter pending transport to the mines. Excess gypsum is stored on site in lined bunkers and shipped offsite for either agricultural use as fertilizer or directly to approved sanitary landfills in Billings or Hardin, Montana. The smelter is considered by the EPA to be a large quantity generator of hazardous wastes that include the following sources:  Laboratory nickel/copper/arsenic/chromium acidic solutions;  Slag, crucibles, and cupels from fire assay contaminated with lead and other metals (e.g., barium, cobalt, chromium, copper, lead, manganese, mercury, nickel and zinc);  Contaminated personal protective equipment;  Waste potassium permanganate;  Iron removal residue solids containing arsenic, cadmium, chromium and lead;  Electrowinning filter cake material contains arsenic;  Electrowinning filter cloth containing lead;  Fluorescent bulbs;  Methyl ethyl ketone contaminated rags; and  Spent aerosol paint canisters. All hazardous wastes are shipped offsite for proper disposal at a permitted, out-of-state Treatment Storage Disposal Facility. The Qualified Persons are of the view that there are no closure or post closure monitoring requirements for this facility. 269 Reclamation Plans and Costs 17.2.6.1 Overview Reclamation plans and bond amounts are available for Stillwater and East Boulder Mines in their respective Consolidated Operations and Reclamation Plan. The Benbow Portal has an independent Plan of Operations, and Reclamation Plan, which has been incorporated into the Stillwater Mine Operating Permit and bonding. The current State bonding is the principal financial instrument covering reclamation and restoration obligations. Reclamation surety bond amounts have been developed using methods provided in the DEQ Bonding Procedures Manual (DEQ, 2001). Reclamation surety bonds run to the benefit of the State of Montana, which issues the Operating Permits, and not to the Federal Government. Direct reclamation costs include, but are not limited to, tailings impoundments; waste rock storage facilities; portals, roads, and diversions interim care and maintenance; closure water treatment; and long-term care and maintenance. Indirect reclamation costs are based on a fixed percentage of direct costs (excluding long-term care and maintenance). Reclamation costs have been developed for forward looking five- year periods with an assumed annual inflation rate of approximately 2%. 17.2.6.2 Stillwater Mine and Hertzler Ranch Facilities Mine closure plans and bond bases of estimate are provided for the Stillwater Mine facilities in the Consolidated Operations and Reclamation Plan and includes the Benbow Portal reclamation plan and bond. . Reclamation for these facilities includes closure and post-closure management of adit waters, tailings storage facility, waste rock storage area, storm water management, and post-closure monitoring and maintenance programs. Post-closure monitoring would address the following items until bond is released and all applicable water quality standards are met:  Groundwater and surface water quality would be monitored three times per year according to the approved water quality monitoring plans and the MPDES permit in place during post- closure;  Shaft water quality would be monitored three times per year and annually thereafter until water quality stabilizes and mine water discharges from the shaft;  Shaft water levels would be monitored three times per year until mine water exits the shaft;  Tailings impoundment function and structural integrity would be monitored annually for the first five years and then once every five years thereafter;  Seepage outlet structures and discharge channel function would be monitored annually for the first five years and then once every five years thereafter;  Hertzler Ranch surface and groundwater monitoring would occur three times per year for nutrients, salts, and biomonitoring;  Water from the Hertzler Ranch tailings storage facility seepage outlet structure would be monitored for quality and flow rate three times per year until water quality stabilizes;  The post-closure maintenance plan would include the following items to be conducted annually during the first five years of closure and once every five years thereafter until bond is released, the MPDES permit is no longer needed, and water quality standards in effect at that time are met: o Function of all ponds including percolation ponds, storm water sediment retention ponds, and Hertzler Ranch LAD storage pond; 270 o Function of storm water, west-side shaft, and seepage outlet structure discharge channels; and o Function of underdrains. Current bonding for reclamation under the Operating Permit 00118 is funded for the amount of $63 000 000. The latest approved minor revision to the Operating Permit (MR241-001) has resulted in $62 263 829 of the $63 000 000 bond being allocated to approved activities, leaving $736 171 unallocated to reclamation obligations. The Qualified Persons understand that the increased costs are being driven by incorporation of the Benbow Exploration Project into the Mine Permit, recent cost of living increases, State estimates of long-term monitoring costs and expanded water treatment associated with the East-side Waste Rock Storage Area. Table 59 presents the Stillwater Mine reclamation schedule and Table 60 presents the reclamation monitoring and maintenance schedule for the mine. Table 59: Stillwater Mine Reclamation Schedule Activity Interim Year 1 of Active Closure Year 2 of Active Closure Year 3 of Active Closure 1st Qtr 2nd Qtr 3rd Qtr 4th Qtr 1st Qtr 2nd Qtr 3rd Qtr 4th Qtr 1st Qtr 2nd Qtr 3rd Qtr 4th Qtr 1st Qtr 2nd Qtr 3rd Qtr 4th Qtr Water Treatment: Water Treatment – Underground water during demo Water Treatment – Tailings Imp Supernatant, Underdrain & O/F Water Treatment – Liberated tailings water during cap placement Site Care & Maintenance Reclamation Activity: Plant Site – Demolition & Removal of Plant Buildings Plant Site – Reclamation Mine – Underground Decommissioning Mine – Adit and Raise Closure Stillwater Impoundment Hertzler Impoundment Water Treatment & LAD Facilities – Demolition & Removal Power Line – Removal


271 Table 60: Stillwater Mine Closure Monitoring and Maintenance Schedule Based on the Qualified Person’s assessment of the reclamation bond calculation and discussions with in-house Environmental Specialists and taking into account the approved Reclamation Plans and understanding of the annual regulatory review of surety bases, the current reclamation costs and liabilities are reasonably managed and funded while existing sureties appear adequate to meet foreseeable commitments for the Stillwater Mine, contingent to final resolution of the Stillwater Mine bond negotiations. 17.2.6.3 East Boulder Mine Mine closure plans and bond bases of estimate are provided for the East Boulder Mine facilities in the Consolidated Operations and Reclamation Plan. Table 61 presents the East Boulder Mine reclamation schedule while Table 62 presents the reclamation monitoring and maintenance schedule for the mine. Concurrent reclamation has occurred since the start of operations. At the time of mine closure and reclamation, all surface facilities will be decommissioned, all structures will be disassembled and removed, and the land will be reclaimed consistent with the approved post-mine land use. Roads that will remain include the main access road to the reclaimed portals, TSF, water conveyance structures, and water monitoring locations to allow for long-term monitoring and maintenance. These roads will be reclaimed when long-term monitoring and maintenance activities cease. Adequate volumes of soil materials are available for replacement of the required soil cover on all disturbances. Reclamation will meet the State of Montana provisions and requirements under the Montana Metal Mine Reclamation 272 Act (MCA 82-4-336). The Closure and Reclamation Plan is also intended to meet the USFS requirements governing mineral development (36 CFR 228.8), and reclamation requirements under the Federal Seed Act (7 U.S.C., Section 1551-1610) and current USFS seeding guidelines. Table 61: East Boulder Mine Reclamation Schedule Activity Interim Year 1 of Active Closure Year 2 of Active Closure Year 3 of Active Closure 1st Qtr 2nd Qtr 3rd Qtr 4th Qtr 1st Qtr 2nd Qtr 3rd Qtr 4th Qtr 1st Qtr 2nd Qtr 3rd Qtr 4th Qtr 1st Qtr 2nd Qtr 3rd Qtr 4th Qtr Water Treatment: Water Treatment – Adit Water Water Treatment – Tailings Imp Supernatant, Underdrain & O/F Water Treatment – Liberated tailings water during cap placement Site Care & Maintenance Reclamation Activity: Plant Site – Demolition & Removal of Plant Buildings ` Plant Site – Reclamation Mine – Underground Demolition and Disposal; Adit & Raise Closure Tailings Impoundment Reclamation Water Treatment & LAD Facilities – Demolition & Removal Boe Ranch Pipeline Reclamation Power Line (within permit area) + 2 sub-stations – Removal Access Roads – Reclamation 273 Table 62: East Boulder Mine Closure Monitoring and Maintenance Schedule Reclamation of East Boulder Mine includes closure and post-closure management of adit waters, tailings storage facility, storm water management, and post-closure monitoring and maintenance programs. Closure and post-closure monitoring would address the following items until bond is released and all applicable water quality standards are met:  Groundwater and surface water quality would be monitored quarterly during closure and then twice per year according to the approved water quality monitoring plans and the MPDES permit in place during post-closure;  Adit water quality and quantity would be monitored three times per year until as long as the MPDES permit is in effect and/or until water quality standards are met;  Tailings impoundment function and structural integrity would be monitored annually during Years four and five and then once every five years;  Seepage outlet structures, seepage through cover discharge channel, adit discharge channel, storm water channel, and percolation pond function would be monitored annually for Years 4 to 8 and then once every five years;  Boe Ranch land application disposal, if constructed, would have a post-closure monitoring plan completed that describes the details of surface and groundwater sampling three times a year for up to five years to document water quality. The embankment on the storage pond would be reduced eliminating the need for inspection of embankment stability. This system has not been constructed or operated;  The post-closure maintenance plan would include the following items to be conducted annually during post-closure Years 4 to 8 and once every five years thereafter until bond is released, the MPDES permit is no longer needed, and water quality standards in effect at that time are met: o Function of all ponds including percolation ponds, storm water sediment retention ponds; o Function of stormwater, adit discharge, and seepage outlet structure discharge channels; o Function of seepage outlet structure and underdrain. Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Year 8 Groundwater Monitoring Surface Water Monitoring Adit Water Monitoring TSF Underdrain TSF Seepage through the Cover Salt Load Monitoring Abandon/Close Monitoring Wells One Time Tailings Volume, Density, Grade Structural Integrity Seepage Outlet Structure, Seepage through the Cover, Discharge Channel, Storm Water Channels Function of all Ponds (including Percolation Pond and Sediment Ponds) Function of Storm Water Channels and Basins, Adit Discharge Channel, TSF Seepage Outlet Channel Function of TSF Cover and Underdrain Outlet Structures Quarterly Quarterly Annual Closure Year ACTIVITY (1) Annual Annual (1) Closure and post‐closure monitoring and maintenance requirements are based on the 2012 Final EIS and ROD. Costs for ensuring these measures are carried out are included in the reclamation bond estimate calculations in Appendix G1 of the CORP. Post‐Closure Year Quarterly As Needed As Needed As Needed Site Maintenance Water Quality Monitoring Semiannual Monthly Semiannual Annual TSF Facility Monitoring Quarterly 274 Current bonding for reclamation under the Operating Permit 00149 is funded for the amount of $30 000 000, with $29 910 748 obligated (through Minor Revision MR23-003) and $89 216 unobligated. The potential Lewis Gulch TSF and the Dry Creek waste rock storage facility, when approved and constructed, would add to surety requirements until the East Boulder Mine is reclaimed and the incremental surety bond amount released. No estimates for those future reclamation liabilities are available. Based on the Qualified Persons’ assessment of the reclamation bond calculation, discussions with Site Environmental Specialist and noting the approved Reclamation Plans and understanding of the annual regulatory review of surety bases, the current reclamation costs and liabilities are reasonably managed and funded, existing sureties appear adequate to meet foreseeable commitments for the East Boulder Mine. 17.2.6.4 Columbus Metallurgical Complex The Columbus Metallurgical Complex does not operate under a comparable Federal or State operating permit like the mines and, as such, no reclamation plan or bond is required. The Qualified Persons can confirm that there are no closure plans contemplated for the Columbus Metallurgical Complex.


275 CAPITAL AND OPERATING COSTS Overview Stillwater and East Boulder Mines and the Columbus Metallurgical Complex have been operated as integrated mature mining, ore processing and mineral beneficiation operations producing PGMs and base metals. Much of the long-term infrastructure and equipment required for the operations is in place, with upgrades implemented to accommodate production increases anticipated in the LoM plans for the operations and/or any technological improvements that bring in operational efficiencies. The capital and operating costs for the three sites were estimated through an integrated, comprehensive budgeting process. Estimates of sustaining capital and operating costs were benchmarked to historical costs, while accounting for changes in production levels, escalation and contingencies. Project capital estimates for productivity enhancement projects were based on quotations from original equipment manufacturers and contractors. The foregoing constitutes sufficient justification for capital and operating cost budgeting for the operations. In addition, the accuracy level in the capital and operating costs utilised for LoM budgeting is within ±15% at up to 10% contingency for Proved Mineral Reserves and ±15% at up to 10% contingency for Probable Mineral Reserves. The capital and operating costs were utilised for the economic viability of the LoM plans for the mines and for the overall Sibanye- Stillwater US PGM Operations. Capital and operating costs in this section are reported by site, namely Stillwater Mine, East Boulder Mine and the Columbus Metallurgical Complex. However, for the purposes of economic viability testing of the LoM plans, the capital and operating costs for the Columbus Metallurgical Complex are assigned to Stillwater and East Boulder Mines proportionately to production at the mines. All costs are presented in real terms and US$. Capital Costs Background Capital cost budgets present the costs into two categories, namely Category 1 and Category 2. Category 1 is essential capital for business continuity and sustaining production at the sites whereas Category 2 capital relates to projects intended for improved productivity, efficiency improvement and the management of environmental and social/administration matters. The Blitz Project, which started in 2011 and centred on expanding mining operations towards the Stillwater East Section and ore processing facilities, has been the most significant Category 2 contributor at Stillwater Mine and the Columbus Metallurgical Complex in recent years. TSF capacity expansion which is in advanced stages of permitting has become the main contributor to Category 2 capital at East Boulder Mine. The accuracy levels stated in Section 18.1 are applicable to both capital expenditure categories. Stillwater Mine 18.2.2.1 LoM Capital Expenditure Schedule The LoM capital cost schedule for the Stillwater Mine is presented in Table 63 where it is also compared with actual capital expenditure for the FY2021 to FY2023 period. 276 The capital costs for Stillwater Mine include capital expenditure for mine and surface equipment, infrastructure, capitalised development, ongoing projects and environmental management, which relate to the mining and ore processing operations. In addition, there has been significant capital expenditure on the Blitz Project (Stillwater East Growth and Project Capital) until FY2022. There was also capital expenditure in FY2023 but at a significantly reduced level. Key changes to the Blitz Project after FY2021 include the following:  TBM Tunnel/Benbow/5600E-Benbow was completed and the 5600E FWL was connected in 2022. Spending on Benbow portal area remediation continued at a reduced rate in FY2023 and this will continue until FY2024;  Much of the capital expenditure previously reported as Growth Capital has been reported under stay in business (SIB) capital costs following the achievement of the desired level of production at the Stillwater East Section in FY2022 which is in line with the Sibanye-Stillwater criteria for reporting capital and operating costs;  Stillwater East Section equipment capital expenditure which was previously reported under Growth Capital has been reported under SIB capital expenditure from FY2022 and any new equipment is covered under the SIB capital expenditure budget;  Stillwater East Section infrastructure which was also reported under Growth Capital has been reported as SIB capital since FY2022. Only infrastructure projects associated with the 5600E/5000E drive have been funded as Growth Capital until completion;  Capital expenditure for the expansion of the Stillwater Concentrator capacity has continued and is expected to be finalised in FY2024. The total capital budget for Stillwater Mine for the FY2024 to FY2054 period is approximately $2.34 billion (i.e. equivalent to $75.32 million per annum on average) and this is dominated by capitalised development (55%). Stillwater Mine’s capital expenditure in the capital budget is detailed by month for the first two years of the LoM and is annualised thereafter until FY2054. Long-term capital expenditure related to a specific project and/or scheduled equipment replacement is forecast in detail based on quotations from original equipment manufacturers and contractors. Routine long-term capital expenditure is forecast based on benchmarking with historical capital expenditure for the capitalised items. 18.2.2.2 Mining Capital The mining capital consists of several elements including development capital and capital associated with certain underground infrastructure upgrades. The following commentary outlines the main highlights of the capital expenditure schedule:  Mine and Surface Equipment Capital: An annual provision averaging approximately $12.42 million has been budgeted for the procurement of additional mining and surface equipment for the Stillwater East and Stillwater West Sections between FY2024 and FY2054, with a peak of $23.66 million in FY2025. The peak expenditure in FY2025 is required for the ongoing replacement of certain primary and secondary underground equipment fleets that are past their normal life cycle replacement schedules. The lifecycle replacements are required to achieve and sustain the planned productivity levels;  Capitalised Development Capital: Capitalised development is defined as the part of primary development which extends or improves the LoM, such as footwall levels, access ramps, and infrastructure development. The capital allowance for development averages $76.01 million per 277 annum between FY2024 and FY2033, which is a lower expenditure level relative to expenditure in FY2022 and FY2023 of $115.55 million and $140.44 million, respectively. The quantum of capitalised development capital declines to an average of $47.35 million per annum from FY2034 to FY2041, and progressively thereafter to $16.43 million in FY2048;  Project Capital: This capital relates to specific, scheduled projects which enhance productivity or extend the life of mine, such as new tip and chute installations and rail extensions. This varies from year to year as requirements dictate but is budgeted at $7.52 million per annum and $233.13 million over the LoM. Higher than average annual expenditure between FY2025 and FY2027 (total of $123.80 million for the three years) relate to the construction of a sand plant in the Stillwater East Section (5500W SWE Paste Plant) and underground water handling infrastructure upgrades. An increase in Project Capital expenditure over the period FY2021 to FY2023 is due to the West Fork Vent Raise Project (approximately $10.00 million);  Infrastructure Capital: This capital also relates to specific scheduled projects but with a focus on items such as communication, information technology (IT), software licences, power supply upgrades and the extension of the centralised blasting system as the mine footprint expands. This is budgeted at an average expenditure of $3.78 million per annum over the LoM;  Other Capital: Other capital was an allocation towards longer term strategic projects such as the development of LoM rock and ventilation passes and there has been no allocation under this category since FY2023 as this expenditure has been moved to Project Capital expenditure;  Stillwater East Expansion (Growth) Capital: This was capital budgeted for the development of the Stillwater East Section in terms of expansion items such as capitalised infrastructure, development, exploration drilling, underground equipment, surface infrastructure expansion, concentrator capacity expansion and concentrate handling facilities. It also accounted for the capital required to establish a LoM rock pass system. As discussed above, most of this expenditure is accounted for in SIB capital;  Stillwater East Project Capital: This was capital budgeted for the establishment of permanent underground infrastructure and access, such as declines and ventilation raises. Most of this is also covered under SIB capital. Stillwater East (Blitz) Growth and Project capital expenditure cease in FY2024 and, thereafter, all mining capital costs associated with the Stillwater East Section will be incorporated in the general Stillwater Mine mining SIB capital expenditure budget. Based on the historical capital expenditure and the detail associated with the various capital budgets, the Qualified Person is of the view that sufficient capital provisions have been allowed for the support of the operations at Stillwater Mine. 18.2.2.3 Concentrator Capital The budgeted concentrator capital comprises modest sustaining capital per annum of between $225 thousand to $300 thousand for process equipment, buildings and infrastructure over the LoM. However, there are also specific capital provisions amounting to $12.65 million for maintenance/replacement of the River Bridge and $3.10 million for compressed air building upgrades between FY2024 and FY2026. With the finalisation of the concentrator expansion, all concentrator capital falls under SIB capital costs. 278 18.2.2.4 Environmental Capital Environmental capital expenditure encompasses TSF expansions, designs and implementation and associated infrastructure maintenance in addition to water and waste rock management and groundwater expenditure. The environmental capital schedule shows expenditure ramp up over two periods. The first period (FY2025 to FY2027) involves modest expenditure of $40.50 million on the next stage of the East Waste Rock Storage Facility (capping and expansion totalling $19.94 million) and water handling infrastructure upgrades resulting from increasing production in the Stillwater East Section. Elevated capital expenditure of $152.80 million in the second period (FY2029 to FY2021) includes $135.40 million for Hertzler TSF Stage 4/5 design and construction. The Hertzler TSF expansion project has initial capital expenditure amount of $6.50 million budgeted for studies over the FY2024 to FY2026 period. Capital expenditure over the remainder of the years is on average $4.82 million per annum which is aligned to historical expenditure. In addition to the LoM total environmental capital expenditure of $314.24 million, there is an allowance totalling $57 million provided for environmental closure. The environmental capital costs include $4.60 million for the final closure and capping of the Nye TSF and TSF replacement.


279 Table 63: Stillwater Mine Actual and LoM Capital Schedule FY2021 FY2022 FY2023 FY2024 FY2025 FY2026 FY2027 FY2028 FY2029 FY2030 FY2031 FY2032 Mine and Surface Equipment US$ 5 075 929 7 947 221 14 116 446 7 030 000 23 656 321 16 061 873 11 288 120 12 864 821 13 116 882 15 120 382 12 488 000 12 365 620 Capitalised Development US$ 55 749 072 115 515 620 140 439 310 78 120 761 79 790 987 80 168 987 77 831 821 71 640 043 62 801 232 81 369 023 83 510 198 71 287 848 Project US$ 7 234 408 14 671 790 17 293 992 2 816 998 22 500 874 51 680 787 49 609 696 8 743 648 3 669 496 1 796 250 8 844 250 31 895 454 Infrastructure US$ 3 009 723 2 458 000 22 917 290 4 913 886 13 328 252 18 080 471 2 362 665 2 284 816 4 106 000 4 106 000 3 930 000 4 030 000 Other US$ 4 546 847 2 732 274 - - - - - - - - - - Stillwater East Growth US$ 108 142 113 47 542 794 13 381 962 275 000 - - - - - - - - Stillwater East Project US$ 36 634 309 24 029 279 5 222 084 604 000 - - - - - - - - Environmental US$ 4 110 241 4 568 589 4 450 678 4 621 003 13 130 000 11 550 000 15 820 000 6 920 000 54 300 000 45 000 000 53 500 000 5 000 000 Total US$ 224 502 642 147 893 494 199 217 716 97 502 648 152 406 434 177 542 118 156 912 301 102 453 329 137 993 610 147 391 655 162 272 448 124 578 921 FY2033 FY2034 FY2035 FY2036 FY2037 FY2038 FY2039 FY2040 FY2041 FY2042 FY2043 FY2044 Mine and Surface Equipment US$ 13 429 765 18 211 632 11 568 265 15 574 632 13 929 132 13 418 271 14 045 638 19 072 138 17 104 265 13 199 385 13 193 512 5 889 253 Capitalised Development US$ 73 538 272 49 894 003 43 301 298 56 022 495 47 236 945 43 988 975 48 689 158 48 650 637 41 051 517 34 257 892 27 736 599 16 882 401 Project US$ 18 844 250 1 000 000 3 246 250 1 000 000 2 246 250 2 000 000 2 246 250 1 000 000 3 246 250 1 000 000 2 246 250 2 000 000 Infrastructure US$ 4 030 000 4 030 000 4 080 000 4 080 000 4 080 000 4 080 000 3 700 000 3 700 000 3 700 000 3 500 000 3 500 000 2 653 880 Environmental US$ 5 000 000 5 000 000 5 000 000 5 000 000 5 000 000 5 000 000 4 100 000 4 100 000 4 100 000 4 100 000 5 100 000 5 100 000 Total US$ 114 842 287 78 135 635 67 195 813 81 677 127 72 492 327 68 487 246 72 781 046 76 522 775 69 202 032 56 057 277 51 776 361 32 525 534 FY2045 FY2046 FY2047 FY2048 FY2049 FY2050 FY2051 FY2052 FY2053 FY2054 Mine and Surface Equipment US$ 14 399 385 17 572 138 15 904 265 13 199 385 14 393 512 5 814 253 8 690 626 511 000 1 553 000 428 000 Capitalised Development US$ 17 010 047 17 195 371 16 890 200 16 427 340 - - - - - - Project US$ 2 246 250 1 000 000 3 246 250 1 000 000 1 000 000 2 000 000 - - 1 000 000 - Infrastructure US$ 2 503 880 2 503 880 2 203 880 1 775 000 1 455 000 1 185 000 1 085 000 975 000 800 000 500 000 Environmental US$ 5 100 000 5 100 000 5 100 000 4 500 000 5 000 000 4 500 000 4 500 000 4 500 000 4 500 000 5 000 000 Total US$ 41 259 561 43 371 388 43 344 595 36 901 725 21 848 512 13 499 253 14 275 626 5 986 000 7 853 000 5 928 000 Cost Centre Unit Cost Centre Unit Actual Cost Centre Unit Budget Budget Budget 280 East Boulder Mine 18.2.3.1 LoM Capital Expenditure Schedule The LoM capital costs for East Boulder Mine also include capital for mine and surface equipment, infrastructure, capitalised development, ongoing projects and environmental management, which relate to the mining and ore processing operations. In addition, East Boulder Mine’s capital expenditure in the capital budget is detailed by month for the first two years of the LoM and is annualised thereafter until the end of the LoM in FY2069. Long-term capital related to a specific project and/or scheduled equipment replacement is forecast in detail based on quotations from original equipment manufacturers and contractors. For routine long-term capital expenditure is forecast based on benchmarking with historical capital expenditure for the capitalised items. The LoM capital cost schedule for East Boulder Mine is presented in Table 64 where it is also compared with actual capital expenditure for the FY2021 to FY2023 period. The total capital budget for East Boulder Mine for the FY2024 to FY2069 period is approximately $1.56 billion (i.e. equivalent to $38.08 million per annum on average) and this is also dominated by capitalised development (47%) as well as mining and surface equipment (32%). 18.2.3.2 Mining Capital The mining capital consists of several elements including development capital and capital associated with certain underground infrastructure upgrades. The following salient points relating to mining capital costs are highlighted:  Mine and Surface Equipment Capital: This is an annual capital provision for the lifecycle replacement of mining equipment. As a result, this expenditure tends to have periods of relative stability and cyclical periods of elevated expenditure associated with major rebuilds and acquisition of new equipment as reflected in the current capital expenditure. Overall, mine and surface equipment capital expenditure during stable years averages approximately $8.58 million per annum and periods of elevated expenditure are associated with expenditure of up to $15.83 million between FY2024 and FY2042. Thereafter until FY2056, mine and surface equipment capital costs are budgeted at levels of $11.83 million to $21.83 million, reducing progressively to $3.50 million in FY2064;  Capitalised Development: Capitalised development is the part of primary development such as footwall levels and access ramps, which extends LoM or optimises the LoM plan. The LoM Capitalised Development Capital budget ranges from $9.12 million to $32.71 million per annum between FY2024 and FY2060. The level of expenditure is significantly lower than the $41.92 million to $42.93 million in FY2022 and FY2023. Capital allowance per annum after FY2060 reduces progressively to approximately $410 thousand in FY2069 due to significantly low levels of capitalised developments planned/required;  Project Capital: The TSF Stage 5/6 Project is the most significant project in the LoM of East Boulder Mine and this is forecast to end in FY2026. The TSF project will account for the bulk of the Project Capital expenditure per annum until FY2026. Subsequent to FY2026, no Project Capital is provided for as there are no major projects planned;  Other Capital: Other capital generally accounts for scheduled light vehicle replacements and minor infrastructural upgrades as required. There is an annual provision of $750 thousand over the period FY2024 to FY2026, after which the annual provision is $350 thousand until FY2050. 281 Based on the historical capital expenditure and the detail associated with the various capital budgets, the Qualified Person is of the view that sufficient mining capital provisions have been made to support the existing operations. 18.2.3.3 Concentrator Capital Due to the concentrator historically having been operated at 75%, there has been limited capital expenditure for sustaining the ore processing operations, with capital in the order of less than $1 million spend annually. Elevated expenditure for process equipment, buildings and infrastructure amounting to $4.88 million is planned over the period FY2024 and FY2026. The capital budget for the concentrator makes for modest provisions of $230 thousand to $150 thousand in FY2027 and FY2028, respectively. The Qualified Person does not expect the sustaining capital costs for the concentrator to significantly increase in future due to plant being operated continuously at higher than 75% utilisation. 18.2.3.4 Environmental Capital Environmental capital expenditure encompasses TSF expansions, designs and implementation and associated infrastructure maintenance in addition to water and waste rock management and groundwater expenditure. The Environmental Capital budget includes an annual provision of $340 thousand for labour for the Lewis Gulch TSF embankment in FY2024 and FY2025, and the same annual provisions for Dry Fork Waste Rock Storage Area labour between FY2026 and FY2028. Approximately $37 million is planned to be spent on the Dry Fork Waste Rock Storage Area Phase 1 development between FY2024 and FY2026 although the total expenditure for Phase 1 to Phase 4 and closure spread over the LoM is approximately $50.70 million. Capital allocations for Phases 2, 3 and 4 construction and lining are respectively $2.90 million in FY2030, $7.50 million in FY2035 and $6.30 million in FY2047. The budget includes $5.50 million for closure of the Dry Fork Waste Rock Storage Area between FY2055 and FY2056. Approximately $5.30 million is budgeted for Stage 6 TSF closure during the FY2031 to FY2033 period. Approximately $66.40 million is planned to be spent on the Lewis Gulch TSF infrastructure and topsoil relocation, embarkment construction and lining, pipelines and underdrain installation and closure over the LoM. Further key elements of the capital expenditure under the environmental budget include an allowance of $100 million for the development of a new TSF between FY2039 and FY2042, an allowance of $7.50 million for the closure of the future TSF. The aggregate $296.78 million LoM environmental capital costs includes $25 million for final closure. There is no environmental capital provision in certain years over which no tailings, waste rock or other environmental projects are anticipated. 282 Table 64: East Boulder Mine Actual and LoM Capital Schedule FY2021 FY2022 FY2023 FY2024 FY2025 FY2026 FY2027 FY2028 FY2029 FY2030 FY2031 FY2032 FY2033 Mine and Surface Equipment US$ 10 077 403 9 560 073 15 921 454 13 643 350 14 308 208 12 150 000 8 555 000 13 295 000 8 575 000 8 325 000 8 475 000 8 325 000 8 475 000 Capitalised Development US$ 20 937 932 42 929 859 40 909 905 14 142 776 23 953 712 19 213 790 16 935 881 21 557 847 26 396 405 20 635 994 26 090 959 17 547 299 21 643 117 Project (Excluding Met Complex) US$ 7 629 862 12 888 929 18 312 355 10 321 345 8 400 866 5 082 980 - - - - - - - Other US$ 467 024 2 556 275 20 592 830 375 000 750 000 750 000 750 000 750 000 750 000 750 000 350 000 350 000 350 000 Environmental US$ 1 478 500 2 001 012 2 541 538 2 590 000 9 625 000 28 440 000 30 340 000 31 740 000 8 000 000 5 900 000 2 000 000 2 000 000 1 300 000 Total US$ 40 590 721 69 936 148 98 278 081 41 072 471 57 037 786 65 636 770 56 580 881 67 342 847 43 721 405 35 610 994 36 915 959 28 222 299 31 768 117 FY2034 FY2035 FY2036 FY2037 FY2038 FY2039 FY2040 FY2041 FY2042 FY2043 FY2044 FY2045 FY2046 Mine and Surface Equipment US$ 15 825 000 8 475 000 8 325 000 8 325 000 8 325 000 8 325 000 8 325 000 8 325 000 8 325 000 15 825 000 15 825 000 15 825 000 11 825 000 Capitalised Development US$ 24 491 233 17 592 750 16 994 541 24 665 514 19 607 027 32 707 987 28 063 542 21 339 468 19 077 896 19 867 341 26 261 295 27 838 919 25 026 256 Project (Excluding Met Complex) US$ - - - - - - - - - - - - - Other US$ 350 000 350 000 350 000 350 000 350 000 350 000 350 000 350 000 350 000 350 000 350 000 350 000 350 000 Environmental US$ - 7 500 000 - - - 33 000 000 28 000 000 25 000 000 25 000 000 2 500 000 2 500 000 2 500 000 6 300 000 Total US$ 40 666 233 33 917 750 25 669 541 33 340 514 28 282 027 74 382 987 64 738 542 55 014 468 52 752 896 38 542 341 44 936 295 46 513 919 43 501 256 FY2047 FY2048 FY2049 FY2050 FY2051 FY2052 FY2053 FY2054 FY2055 FY2056 FY2057 FY2058 FY2059 Mine and Surface Equipment US$ 17 825 000 17 825 000 17 825 000 17 825 000 19 825 000 21 825 000 21 825 000 21 825 000 21 825 000 21 825 000 10 300 000 10 300 000 10 300 000 Capitalised Development US$ 18 780 035 17 585 915 17 377 362 16 095 841 22 993 230 11 350 741 18 306 166 25 201 042 17 584 142 9 467 052 9 357 744 14 717 887 9 136 291 Project (Excluding Met Complex) US$ - - - - - - - - - - - - - Other US$ 350 000 350 000 350 000 350 000 - - - - - - - - - Environmental US$ - - - - - - - - 3 000 000 5 000 000 12 500 000 12 500 000 5 000 000 Total US$ 36 955 035 35 760 915 35 552 362 34 270 841 42 818 230 33 175 741 40 131 166 47 026 042 42 409 142 36 292 052 32 157 744 37 517 887 24 436 291 FY2060 FY2061 FY2062 FY2063 FY2064 FY2065 FY2066 FY2067 FY2068 FY2069 Mine and Surface Equipment US$ 3 500 000 3 500 000 3 500 000 3 500 000 3 500 000 - - - - - Capitalised Development US$ 9 239 476 4 116 697 470 918 5 006 691 473 063 470 107 469 455 427 711 355 150 409 579 Project (Excluding Met Complex) US$ - - - - - - - - - - Other US$ - - - - - - - - - - Environmental US$ - - - - - - - - - - Total US$ 12 739 476 7 616 697 3 970 918 8 506 691 3 973 063 470 107 469 455 427 711 355 150 409 579 Budget Budget Budget Budget Cost Centre Unit Cost Centre Unit Cost Centre Unit Actual Cost Centre Unit


283 Columbus Metallurgical Complex Until FY2021, the Metallurgical Complex has experienced progressive increase in concentrate delivery from the concentrators as a result of ore production increases at Stillwater and East Boulder Mines. Due to the issues affecting ore production at Stillwater and East Boulder Mines mainly relating to the COVID- 19 pandemic restriction and flood event, the concentrate production ramp up slowed down over the FY2022 to FY2023 period. From the FY2022 to FY2023 low, the combined ore tons mined and processed continue to increase until FY2029 after which annual ore and concentrate outputs will stabilise as both mines operate at steady state production levels until FY2053 when production ramp down at Stillwater Mine commences. As a result of the progressive increase in tonnage primarily as part of the Blitz Project, several capital projects have been underway at the Columbus Metallurgical Complex as described in Section 14.3, many of which have since been completed. The LoM capital cost schedule for the Columbus Metallurgical Complex is presented in Table 65 where it is also compared with actual capital expenditure for the FY2021 to FY2023 period. With the finalisation of the various projects at the Columbus Metallurgical Complex in FY2023, sustaining capital becomes the single most significant capital cost element. The provision for sustaining capital ranges from $2.30 million to $32.86 million per annum (average of $13.08 million over the LoM), with the lower amounts reflecting modest annual maintenance of the various units of the complex and larger amounts associated with cyclic major furnace rebuilds. The total capital budget for the Columbus Metallurgical Complex for the FY2024 to FY2061 period is approximately $601.81 million. The Qualified Persons are satisfied with the levels of project and sustaining capital provided for the various projects and for the continuity of operations at the Columbus Metallurgical Complex. The sustaining capital costs are aligned to actual capital expenditure for the FY2021 to FY2023 period. 284 Table 65: Columbus Metallurgical Complex Actual and LoM Capital Expenditure FY2021 FY2022 FY2023 FY2024 FY2025 FY2026 FY2027 FY2028 FY2029 FY2030 FY2031 FY2032 FY2033 Sustaining Capital $ 15 966 015 9 606 390 21 552 799 13 008 000 32 855 057 21 565 000 14 323 400 15 288 000 13 470 000 21 130 000 9 590 000 8 160 000 9 190 000 Smelter Projects $ 8 540 183 1 184 488 253 078 - - - - - - - - - - BMR Projects $ 1 545 358 11 415 - - - - - - - - - - - Other (Recycle/Lab Expansion Projects) $ 1 134 365 2 996 552 2 874 786 - - - - - - - - - - Total $ 27 185 921 13 798 845 24 680 663 13 008 000 32 855 057 21 565 000 14 323 400 15 288 000 13 470 000 21 130 000 9 590 000 8 160 000 9 190 000 FY2034 FY2035 FY2036 FY2037 FY2038 FY2039 FY2040 FY2041 FY2042 FY2043 FY2044 FY2045 FY2046 Sustaining Capital $ 21 345 000 14 765 000 9 535 000 8 965 000 11 535 000 16 080 000 23 920 000 12 000 000 10 410 000 12 565 000 23 505 000 16 265 000 13 315 000 Smelter Projects $ - - - - - - - - - - - - - BMR Projects $ - - - - - - - - - - - - - Other (Recycle/Lab Expansion Projects) $ - - - - - - - - - - - - - Total $ 21 345 000 14 765 000 9 535 000 8 965 000 11 535 000 16 080 000 23 920 000 12 000 000 10 410 000 12 565 000 23 505 000 16 265 000 13 315 000 FY2047 FY2048 FY2049 FY2050 FY2051 FY2052 FY2053 FY2054 FY2055 FY2056 FY2057 FY2058 FY2059 Sustaining Capital $ 15 790 000 11 360 000 16 265 000 24 355 000 11 665 000 10 130 000 10 620 000 9 380 000 14 080 000 9 845 000 8 895 000 9 635 000 9 470 000 Smelter Projects $ - - - - - - - - - - - - - BMR Projects $ - - - - - - - - - - - - - Other (Recycle/Lab Expansion Projects) $ - - - - - - - - - - - - - Total $ 15 790 000 11 360 000 16 265 000 24 355 000 11 665 000 10 130 000 10 620 000 9 380 000 14 080 000 9 845 000 8 895 000 9 635 000 9 470 000 FY2060 FY2061 FY2062 FY2063 FY2064 FY2065 FY2066 FY2067 FY2068 FY2069 Sustaining Capital $ 20 310 000 9 190 000 7 630 000 7 325 000 7 950 000 12 525 000 6 705 000 5 300 000 5 300 000 5 300 000 Smelter Projects $ - - - - - - - - - - BMR Projects $ - - - - - - - - - - Other (Recycle/Lab Expansion Projects) $ - - - - - - - - - - Total $ 20 310 000 9 190 000 7 630 000 7 325 000 7 950 000 12 525 000 6 705 000 5 300 000 5 300 000 5 300 000 Parameter Unit Budget Budget Budget Budget Unit Parameter Actual Parameter Parameter Unit Unit 285 Operating Costs Background Operating costs for Stillwater and East Boulder Mines are reported according to mining and surface facilities categories and in terms of unit cost per ton of ore processed ($/ton processed) at the concentrators. Operating costs for the Columbus Metallurgical Complex are reported according to unit cost per ton of PGM-base metal concentrate smelted and include the costs of transporting concentrate all downstream mineral beneficiation and laboratory costs. The operating costs for the Columbus Metallurgical Complex also account for revenue credits from recycling operations and secondary metals. The costs are benchmarked to historical costs at each site and make allowances for escalation and increased productivity where necessary. The forecast operating costs for all operations are based on historic actual costs and are estimated to be within ±10-15% level of accuracy in real terms. Stillwater Mine 18.3.2.1 LoM Operating Costs The LoM operating costs for Stillwater Mine reported for the mining and surface facilities categories and in terms of unit cost per ton of ore processed are presented in Table 66. Significant escalation of the total unit operating costs from $293.23/ton milled in FY2021 to $499.80/ton milled in FY2023 (70% overall increase over the period) and a progressive decline relating to increasing tonnage output and steady state operations thereafter until FY2049 are the major highlights of the LoM operating costs. The costs are forecast to improve further and remain stable in the last six years of the LoM due to inter alia the cessation of primary development. 18.3.2.2 Mining Operating Costs The unit mining operating costs for the Stillwater Mine consist of the following key costing elements:  Stope mining costs dependant on mining method employed;  Primary development costs depending on type;  Secondary development costs depending on type;  Underground operational support services depending on activity;  Surface facilities; and  Site specific general and administration costs. In general, unit mining operating costs constitute 88% of the total operating cost for Stillwater Mine over the LoM. The historical and forecast LoM unit mining operating costs reflect significant year-on-year escalation (10% to 58%, and aggregate 73%) between FY2021 ($259.60/ton milled) and FY2023 ($449.99/ton milled) driven mainly by tonnage reduction, significant increases in primary development and underground support costs (driven by high increases in steel costs), blasting costs following the switch to centralised blasting and increased use of higher cost contractors in place of lower cost inhouse personnel due to high employee attrition. Linked to these cost increases are the increases in stoping costs. The mining unit operating cost is forecast to progressively decline to $231.35/ton milled in FY2048, reflecting the combined effect of increasing ore mining and operating at steady state level, improving further to approximately $187/ton milled in the last six years. The step change in the declining trend in 286 FY2049 is due to a reduction in mining activity (primary development and infrastructure establishment) as the mine draws to a close. 18.3.2.3 Surface Facilities Operating Costs The unit operating costs for processing of the ores and maintenance are included in the Surface Facilities Cost Category. This category comprises the following elements:  Concentrator costs;  Paste plant costs;  CRF plant costs;  Sand plant costs;  Shaft/hoisting and surface crusher area costs; and  Hertzler TSF costs. The unit operating cost history and budget for the surface facilities follows a similar trend as for the mining operating costs, with significant year-on-year escalation (11% to 34% and aggregate 48%) between FY2021 ($33.63/ton milled) and FY2023 ($49.81/ton milled), reflecting significant escalation in the price of inputs across the board and a reduction in tonnage milled. From the FY2023 peak, there is significant reversal of the trend as the costs decline to $37.99/ton milled in FY2024 from where the costs remain stable (ranging between $37.87 and $40.65 per ton milled) due to increasing production output and operating at the steady state level. A notable reduction in surface facilities operating from FY2049 onwards until the end of the LoM, mainly due to a reduction in concentrator operating costs, is also forecast. East Boulder Mine 18.3.3.1 LoM Operating Costs The LoM operating costs are also reported according to mining and surface facilities categories and in terms of unit cost per ton of ore processed as shown in Table 67. This shows rapid escalation of the total unit operating costs from $184.03/ton milled in FY2021 to $311.80/ton milled in FY2022 (69% overall increase over the period). The forecast total unit operating cost improves significantly (25%) in FY2024 to $233.15/ton milled, gradually receding to $228.52/ton milled in FY2028, thereafter progressively increasing to $250.49/ton milled In FY2032. The unit operating cost progressively improves from this level reaching $159.76/ton milled in FY2069. 18.3.3.2 Mining Operating Costs The unit mining operating costs for the East Boulder Mine consist of the following key costing elements:  Stope mining costs dependant on mining method employed;  Primary development costs depending on type;  Secondary development costs depending on type;  Underground operational support services depending on activity;  Surface facilities; and  Site specific general and administration costs.


287 In general, unit mining operating costs constitute 90% of the total unit operating cost for East Boulder Mine over the LoM. As a result, the unit mining operating costs follow the same trend as the total unit operating costs. These indicate year-on-year increases of 13% to 53% between FY2021 ($164.56/ton milled) and FY2023 ($284.65/ton milled) and 73% overall increase over the period, also driven by significant increases in underground support costs, blasting costs and increased use of contractors as well as the linked increases in stoping and primary development costs. The costs are forecast to stabilise after a reduction to $209.30/ton milled in FY2024, thereafter fluctuating between $209.84/ton and $215.51/ton milled until FY2029. Subsequently, the costs rise to $226.70/ton milled in FY2033 and fluctuate between this level and $217.78/ton milled until FY2038. Between FY2038 and FY2059, the costs fluctuate between $197.17/ton milled and $223.73/ton milled and, thereafter, progressively decrease to $140.91/ton milled in FY2069. The reduction in the later years of the LoM is consistent with the reduction in mining activity (primary development and infrastructure establishment) as the mine draws to a close. 18.3.3.3 Surface Facilities Operating Costs The unit operating costs for the processing of the ores and maintenance are included in the Surface Facilities Cost Category. This category comprises the following elements:  Concentrator costs;  Sand plant costs; and  Surface crew costs. The unit operating cost history and budget for the surface facilities also indicate rapid year-on-year growth between FY2021 ($19.46/ton milled) and FY2023 ($27.15/ton milled). From the FY2022 peak, the costs are forecast to decline to $24.84/ton milled in FY2025 mainly due to a reduction in concentrator operating costs as well as modest reductions in sand plant and surface crew costs. Between FY2024 and FY2066, the unit operating cost fluctuates between $21.71/ton milled and $25.68/ton milled after which it progressively recedes to $18.75/ton milled in FY2069 Due to declining concentrator operating costs final years of the LoM. Columbus Metallurgical Complex The LoM unit operating costs for the Columbus Metallurgical Complex are presented in terms of unit cost per ton of PGM-base metal concentrate smelted in Table 68. The costs account for the following elements:  Concentrate transportation;  Smelting;  Refining (which includes environmental, safety, human resources and maintenance);  Laboratory costs;  Site support services (includes purchasing and warehousing);  Site General & Administrative costs (which include all corporate overhead costs);  By-product credits (returned from Precious Metal Refinery); and  Secondary credits (the cost incurred in the catalyst recycling process and credits received for this). Excluding Site General & Administrative costs as well as by-product and secondary credits, the forecast operating costs for the Columbus Metallurgical Complex are in line with those historically achieved after 288 accounting for inflation. The unit costs are forecast to improve with increasing concentrate volumes as Stillwater Mine achieves steady state production levels. Site support services costs, which are reported separately in the LoM budget, are combined with other costs in the actual data for FY2021 to FY2023. The Qualified Person notes the substantial beneficial impact of recycling and by-product credits on the overall unit cost of operation and the benefits arising from the integration of the mining, ore processing and mineral beneficiation operations. Similarly, Site General & Administrative costs significantly improve from FY2024 onwards due to consideration of the 45X tax credit which is applicable to eligible to domestically produced clean energy components in the clean energy supply chain. As the output from Stillwater Mine declines towards the end of the LoM in FY2055, the unit operating costs for the Columbus Metallurgical Complex increase and become positive in FY2054, stabilising at approximately $2 000/ton of concentrate smelted for the remainder of the LoM. Accordingly, there is significant merit in maintaining production at the steady state level and extending the LoM for Stillwater Mine beyond FY2055 through ongoing definition drilling which generates additional Indicated and Measured Mineral Resources for inclusion in the LoM production schedule in future. 289 Table 66: Actual and LoM Operating Costs for Stillwater Mine FY2021 FY2022 FY2023 FY2024 FY2025 FY2026 FY2027 FY2028 FY2029 FY2030 FY2031 FY2032 FY2033 FY2034 FY2035 FY2036 FY2037 Mining: Stope Mining $/ton processed 72.04 84.45 86.07 79.19 76.95 75.83 72.61 73.42 74.61 69.48 74.18 74.55 73.02 78.59 79.35 76.10 78.36 Primary Development $/ton processed 26.87 67.22 82.15 40.02 40.05 33.68 31.30 27.45 21.74 26.41 28.02 23.99 24.70 17.96 15.55 19.76 17.09 Underground Support $/ton processed 134.57 221.00 241.69 190.46 188.98 178.49 169.44 159.93 155.35 153.61 156.52 155.38 154.94 154.57 154.15 153.13 153.58 Site General & Administration $/ton processed 26.11 36.56 40.08 37.36 38.61 35.54 34.39 31.13 30.60 30.07 30.07 30.06 30.07 30.08 30.04 30.07 30.09 Subtotal $/ton processed 259.60 409.23 449.99 347.02 344.59 323.54 307.73 291.93 282.30 279.56 288.80 283.97 282.73 281.21 279.09 279.05 279.12 Surface Facilities: Concentrator $/ton processed 15.26 24.03 28.52 21.43 22.08 24.97 24.71 24.30 24.36 24.74 24.74 24.75 24.74 24.74 24.73 24.75 24.75 Paste Plant $/ton processed 3.24 3.19 3.59 3.53 3.63 3.37 3.33 3.27 3.24 3.23 3.23 3.23 3.23 3.23 3.23 3.23 3.23 Sand Plant $/ton processed 4.35 6.15 6.02 4.63 4.67 5.19 5.30 4.80 4.56 4.49 4.49 4.50 4.49 4.49 4.49 4.50 4.49 Surface Crew $/ton processed 5.58 5.49 5.89 2.53 2.55 1.97 1.90 1.77 1.69 1.66 1.71 1.68 1.67 1.68 1.67 1.66 1.67 Shaft/Hoist/Crusher $/ton processed 3.62 4.72 4.26 3.70 3.72 3.17 3.01 2.67 2.69 2.65 2.65 2.65 2.65 2.65 2.65 2.65 2.65 TSF Costs - Hertzler TSF $/ton processed 1.58 1.44 1.53 2.17 2.18 1.98 1.83 1.74 1.69 1.68 1.73 1.71 1.70 1.69 1.69 1.67 1.68 Subtotal $/ton processed 33.63 45.02 49.81 37.99 38.82 40.65 40.07 38.54 38.22 38.45 38.54 38.52 38.48 38.49 38.45 38.47 38.47 Total Mining and Processing Costs $/ton processed 293.23 454.25 499.80 385.01 383.41 364.19 347.80 330.48 320.53 318.02 327.34 322.50 321.21 319.70 317.54 317.52 317.59 FY2038 FY2039 FY2040 FY2041 FY2042 FY2043 FY2044 FY2045 FY2046 FY2047 FY2048 FY2049 FY2050 FY2051 FY2052 FY2053 FY2054 Mining: Stope Mining $/ton processed 77.00 74.44 74.67 74.05 75.48 74.19 73.17 69.76 66.36 59.77 63.84 60.91 60.10 60.10 60.10 60.10 60.10 Primary Development $/ton processed 15.86 17.53 17.28 15.05 12.53 10.60 6.21 6.10 6.07 5.84 5.91 0.00 0.00 0.00 0.00 0.00 0.00 Underground Support $/ton processed 152.80 150.05 150.81 149.34 147.67 145.51 143.20 139.38 137.94 129.52 131.89 106.75 105.61 108.43 104.88 109.19 106.28 Site General & Administration $/ton processed 30.05 30.08 30.10 30.07 30.07 30.05 30.08 29.98 29.71 29.67 29.71 21.51 21.28 21.85 21.13 22.00 21.42 Subtotal $/ton processed 275.71 272.10 272.86 268.51 265.75 260.35 252.66 245.22 240.07 224.79 231.35 189.18 186.99 190.38 186.12 191.29 187.81 Surface Facilities: Concentrator $/ton processed 24.74 24.74 24.76 24.74 24.74 24.73 24.75 24.71 24.74 24.73 24.75 14.68 14.53 14.91 14.43 15.02 14.62 Paste Plant $/ton processed 3.23 3.23 3.23 3.23 3.23 3.23 3.23 3.23 3.23 3.23 3.23 2.15 2.13 2.18 2.11 2.20 2.14 Sand Plant $/ton processed 4.49 4.49 4.50 4.49 4.49 4.49 4.50 4.48 4.49 4.49 4.50 2.90 2.87 2.95 2.85 2.97 2.89 Surface Crew $/ton processed 1.67 1.65 1.65 1.66 1.65 1.62 1.61 1.59 1.59 1.52 1.53 1.32 1.31 1.34 1.30 1.35 1.31 Shaft/Hoist/Crusher $/ton processed 2.65 2.65 2.66 2.65 2.65 2.65 2.65 2.64 2.65 2.65 2.65 2.01 1.99 2.04 1.97 2.05 2.00 TSF Costs - Hertzler TSF $/ton processed 1.67 1.62 1.63 1.61 1.58 1.55 1.53 1.47 1.43 1.26 1.30 1.19 1.18 1.21 1.17 1.22 1.18 Subtotal $/ton processed 38.44 38.39 38.44 38.38 38.34 38.28 38.27 38.12 38.14 37.87 37.97 24.25 23.99 24.63 23.83 24.81 24.15 Total Mining and Processing Costs $/ton processed 314.15 310.49 311.30 306.89 304.09 298.63 290.93 283.34 278.21 262.66 269.32 213.43 210.99 215.02 209.95 216.10 211.95 Cost Centre Unit Actual Cost Centre Unit Budget Budget 290 Table 67: Actual and LoM Operating Cost for East Boulder Mine


291 Table 68: Actual and LoM Operating Costs for the Columbus Metallurgical Complex FY2021 FY2022 FY2023 FY2024 FY2025 FY2026 FY2027 FY2028 FY2029 FY2030 FY2031 FY2032 FY2033 FY2034 FY2035 FY2036 FY2037 Mineral Beneficiation Costs (Off-mine): Concentrate Transportation $/ton Smelted 113.76 353.79 235.67 132.53 134.65 141.28 150.90 152.35 152.56 154.10 153.94 152.10 151.22 149.78 147.27 146.13 144.95 Smelting $/ton Smelted 798.66 886.77 884.31 872.38 917.04 854.90 815.20 768.92 746.00 739.87 738.56 737.72 738.30 743.50 731.11 740.71 738.59 Refining $/ton Smelted 178.82 205.83 198.29 194.31 276.82 181.56 174.33 163.89 157.03 157.31 153.31 152.30 152.79 151.89 148.54 147.88 147.17 Laboratory $/ton Smelted 124.31 212.57 207.34 213.02 267.57 196.93 186.37 174.05 167.96 166.33 165.99 165.77 165.92 167.32 164.02 166.58 166.02 Columbus Support Services $/ton Smelted - - - 262.81 304.24 230.23 216.68 202.27 196.18 193.34 195.05 195.21 195.22 198.20 194.57 199.40 198.90 Site General & Administrative $/ton Smelted 1 268.20 1 516.69 1 629.87 327.78 342.60 318.71 299.76 277.66 266.73 263.80 263.17 262.77 263.05 265.53 259.62 264.20 263.19 By-product Credits $/ton Smelted -2 331.10 -2 206.89 -1 135.71 -871.30 -865.70 -925.01 -990.54 -1 003.83 -995.29 -1 018.20 -987.66 -969.41 -967.61 -959.62 -935.13 -908.88 -896.55 Secondary Credits (including Interest) $/ton Smelted -3 137.82 -2 716.68 -863.55 -513.63 -775.73 -990.35 -1 065.25 -1 074.07 -1 027.58 -1 073.29 -972.40 -937.53 -943.14 -884.63 -858.05 -779.57 -758.89 Total Costs $/ton Smelted -2 985.17 -1 747.92 1 156.21 617.90 601.49 8.24 -212.56 -338.76 -336.42 -416.74 -290.05 -241.06 -244.26 -168.03 -148.04 -23.55 3.39 FY2038 FY2039 FY2040 FY2041 FY2042 FY2043 FY2044 FY2045 FY2046 FY2047 FY2048 FY2049 FY2050 FY2051 FY2052 FY2053 FY2054 Mineral Beneficiation Costs (Off-mine): Concentrate Transportation $/ton Smelted 145.94 144.52 144.07 141.65 140.87 142.35 143.04 142.15 138.27 138.84 138.58 144.63 144.37 151.69 147.26 158.29 150.26 Smelting $/ton Smelted 739.76 731.40 731.38 729.82 725.74 719.75 722.63 722.05 724.66 728.02 730.20 733.39 752.40 734.41 731.65 758.58 1 095.18 Refining $/ton Smelted 150.17 148.53 148.25 148.23 147.47 145.51 145.38 145.10 142.62 143.34 144.12 148.53 152.78 149.08 148.56 153.13 232.80 Laboratory $/ton Smelted 166.32 164.10 164.09 163.68 162.59 161.00 161.77 161.62 162.32 163.22 163.79 164.63 169.69 164.90 164.17 171.33 260.85 Columbus Support Services $/ton Smelted 197.53 194.70 194.81 194.13 192.72 191.18 192.55 192.48 195.23 196.35 196.84 195.61 201.75 195.79 194.77 204.51 309.40 Site General & Administrative $/ton Smelted 263.75 259.76 259.75 259.00 257.05 254.20 255.57 255.29 256.54 258.14 259.18 260.71 269.78 261.20 259.88 272.73 433.40 By-product Credits $/ton Smelted -924.65 -917.55 -912.33 -905.24 -901.55 -900.39 -898.09 -893.17 -849.37 -847.64 -849.40 -910.47 -917.63 -946.33 -931.86 -970.53 -996.09 Secondary Credits (including Interest) $/ton Smelted -837.68 -853.04 -849.33 -855.91 -861.15 -843.66 -821.86 -812.49 -723.06 -710.92 -720.40 -827.30 -841.61 -845.90 -854.38 -813.97 -958.57 Total Costs $/ton Smelted -98.86 -127.59 -119.31 -124.64 -136.25 -130.05 -99.01 -86.96 47.22 69.36 62.90 -90.27 -68.45 -135.15 -139.95 -65.93 527.21 FY2055 FY2056 FY2057 FY2058 FY2059 FY2060 FY2061 FY2062 FY2063 FY2064 FY2065 FY2066 FY2067 FY2068 FY2069 Mineral Beneficiation Costs (Off-mine): Concentrate Transportation $/ton Smelted 131.15 132.02 131.99 132.15 135.27 139.88 139.58 138.14 141.37 135.51 130.66 128.08 127.97 126.00 132.31 Smelting $/ton Smelted 1 907.99 1 828.31 1 727.55 1 813.24 1 772.31 1 836.25 1 822.45 1 828.10 1 876.67 1 770.08 1 723.08 1 686.05 1 708.55 1 669.60 2 919.11 Refining $/ton Smelted 424.00 406.02 383.01 402.61 394.00 409.68 406.46 407.42 419.26 393.55 381.68 372.62 377.73 368.37 655.08 Laboratory $/ton Smelted 477.01 455.82 429.02 451.81 440.92 457.92 454.25 455.76 468.67 440.33 427.83 417.99 423.97 413.61 745.94 Columbus Support Services $/ton Smelted 567.11 541.22 509.28 536.50 522.35 540.83 536.71 539.03 553.23 521.43 508.32 497.40 504.62 492.74 892.46 Site General & Administrative $/ton Smelted 821.36 783.33 735.24 776.14 756.60 787.12 780.53 783.23 806.41 755.54 733.10 715.43 726.17 707.58 1 303.99 By-product Credits $/ton Smelted -962.16 -889.90 -889.25 -899.22 -918.21 -962.61 -959.84 -948.87 -976.20 -923.49 -883.53 -860.25 -860.40 -841.99 -951.18 Secondary Credits (including Interest) $/ton Smelted -1 219.96 -1 152.02 -1 141.01 -1 160.80 -1 168.86 -1 215.50 -1 208.20 -1 199.77 -1 225.68 -1 173.86 -1 136.23 -1 113.14 -1 116.05 -1 097.92 -1 320.20 Total Costs $/ton Smelted 2 146.51 2 104.80 1 885.83 2 052.43 1 934.39 1 993.57 1 971.95 2 003.03 2 063.75 1 919.08 1 884.92 1 844.18 1 892.56 1 837.99 4 377.50 Cost Centre Unit Budget Budget Budget Cost Centre Unit Actual Cost Centre Unit 292 ECONOMIC ANALYSIS Background The LoM production, capital and operating cost schedules for Stillwater and East Boulder Mines and the Columbus Metallurgical Complex were employed for the economic viability testing of the LoM plans for each mine and the consolidated LoM plan for the Sibanye-Stillwater US PGM Operations. The consolidated LoM plan forms the basis for the Mineral Reserve estimates for Stillwater and East Boulder Mines reported in this TRS. The LoM production schedules for Stillwater and East Boulder Mines are discussed in Section 13.8 while the associated LoM capital and operating costs are presented in Section 18. No exchange rates have been used for the economic analysis as all metal prices and costs are reported in the US currency. The Qualified Persons for Mineral Reserves have considered and applied the macroeconomic trends, data and assumptions, marketing information and commodity prices, taxation and royalties provided by Sibanye-Stillwater set out below. The outputs of the economic viability testing are reliant on these forward-looking economic parameters and assumptions which may be subject to revision as circumstances change. Economic Viability Testing Method The Discounted Cash Flow (DCF) methodology has been used for the economic testing of the individual LoM plans and consolidated LoM Plan for Sibanye-Stillwater US PGM Operations and the Mineral Reserves for Stillwater and East Boulder Mines. The DCF model is referred to as the Ore Reserve Economic Test (ORET) Model. With the DCF approach, a negative cash flow or NPV indicates sub-economic production whereas a positive cash flow or NPV indicates economic production and that the declaration of Mineral Reserves is justified. The method, therefore, allows for the identification of sub- economic production for exclusion through production schedule tail cutting if the sub-economic production occurs towards the final years of the LoM. A first-pass LoM plan for each mine that included the LoM production schedule and all operating and capital expenses, manpower requirements, equipment replacement and purchase, and primary and secondary development including ventilation and haulages that are needed to execute the plan was incorporated into the ORET Model. The first pass LoM plans for Stillwater and East Boulder Mines were consolidated to produce a single LoM plan for the Sibanye-Stillwater US PGM Operations. Cash flows have been forecast and discounted back to an NPV using a range of real discount rates from 2.5% to 7.5%. The LoMs for Stillwater and East Boulder Mines are 31 and 46 years, respectively. The 31-year LoM plan for Stillwater Mine contemplates driving footwall lateral declines and other infrastructure into areas currently classified as Inferred Mineral Resources, which are not scheduled for mining in the current LoM plan for the mine. Both mines have expanded in this manner over the years. Accordingly, the fact that Stillwater and East Boulder Mines have different LoMs is not a material issue. The ORET Model start date is 1 January 2024 and the LoM for the Sibanye-Stillwater US PGM Operations is 46 years. Financial years commencing 1 January have been used and each year’s cash flow is deemed to have occurred at the end of the period – i.e., on December 31. No assessed losses, 293 shareholder loan accounts or other balance sheet circumstances have been accounted for and, therefore, the cash flows are ungeared. Company tax and state royalty calculations have been incorporated into the computation of cash flows. Economic Assumptions and Forecasts Taxation With guidance from Sibanye-Stillwater, the Qualified Person for Mineral Reserves applied an aggregate tax rate of 24.37% for economic testing of the individual and consolidated LoM Plan for the Sibanye- Stillwater US PGM Operations in support of the declaration of Mineral Reserves for Stillwater and East Boulder Mines. This rate is made up of the cash tax rates for the State of Montana and Federal taxes. Taxation is calculated on real cash flows. Metal Price Forecast For the economic viability testing of the individual and the consolidated LoM Plan for Sibanye-Stillwater US PGM Operations, the forward-looking palladium and platinum metal prices as summarised in Table 48 have been used, and the rationale for the price determination is set out in Section 16.4. These prices have also been submitted by Sibanye-Stillwater to the SEC for review and noting. Discount Rate Sibanye-Stillwater’s internal benchmark real discount rate for the US PGM operations as at 31 December 2023 is 5%, based on corporate planning guidance. The Qualified Person for Mineral Reserves reviewed the base data utilised for the calculation of this internal benchmark discount rate as well as the calculation methodology for reasonableness. From the review, the Qualified Person concluded that the 5% internal benchmark real discount rate is reasonable for the discounting of cash flows for the Sibanye- Stillwater US PGM Operations. DCF Results and Sensitivity Analysis DCF Model An abridged cash-flow model showing expected annual cash flows for Stillwater and East Boulder Mines and the combined Sibanye-Stillwater US PGM Operations is presented in Table 69. 294 Table 69: Abridged Cash Flow Results (Cont’d on the Next Page) East Boulder Mine 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 Palladium ounces produced 143,597 143,559 152,262 168,074 168,074 168,074 168,074 168,074 168,074 168,074 170,633 170,837 166,311 166,685 165,883 164,572 161,648 166,158 168,122 168,945 167,331 169,225 167,512 163,621 162,983 165,309 149,922 163,018 163,490 162,924 161,450 148,792 157,021 167,276 158,651 Platinum ounces produced 41,169 41,158 43,653 48,186 48,186 48,186 48,186 48,186 48,186 48,186 48,920 48,978 47,680 47,788 47,558 47,182 46,344 47,637 48,200 48,436 47,973 48,516 48,025 46,909 46,726 47,393 42,982 46,736 46,872 46,709 46,287 42,658 45,017 47,957 45,484 Com bined ounces produced 184,766 184,717 195,915 216,260 216,260 216,260 216,260 216,260 216,260 216,260 219,552 219,815 213,991 214,473 213,440 211,753 207,992 213,795 216,321 217,380 215,304 217,741 215,536 210,530 209,709 212,702 192,903 209,754 210,362 209,633 207,736 191,450 202,039 215,233 204,135 Palladium revenues $m 179.5 179.4 190.3 210.1 210.1 210.1 210.1 210.1 210.1 210.1 213.3 213.5 207.9 208.4 207.4 205.7 202.1 207.7 210.2 211.2 209.2 211.5 209.4 204.5 203.7 206.6 187.4 203.8 204.4 203.7 201.8 186.0 196.3 209.1 198.3 Platinum revenues $m 51.5 51.4 54.6 60.2 60.2 60.2 60.2 60.2 60.2 60.2 61.1 61.2 59.6 59.7 59.4 59.0 57.9 59.5 60.2 60.5 60.0 60.6 60.0 58.6 58.4 59.2 53.7 58.4 58.6 58.4 57.9 53.3 56.3 59.9 56.9 Gross Revenues $m 231.0 230.9 244.9 270.3 270.3 270.3 270.3 270.3 270.3 270.3 274.4 274.8 267.5 268.1 266.8 264.7 260.0 267.2 270.4 271.7 269.1 272.2 269.4 263.2 262.1 265.9 241.1 262.2 263.0 262.0 259.7 239.3 252.5 269.0 255.2 Less Smelting, refining & transportation $m (23.4) (25.3) (22.1) (22.7) (21.5) (20.9) (20.7) (20.7) (20.7) (20.7) (20.5) (21.3) (20.5) (20.8) (20.7) (21.2) (21.2) (21.5) (21.8) (22.1) (21.8) (21.8) (21.9) (21.5) (21.4) (21.1) (19.5) (20.8) (21.1) (20.9) (29.6) (47.2) (47.5) (48.0) (47.6) Net Smelting Returns $m 207.5 205.6 222.8 247.6 248.8 249.4 249.6 249.6 249.6 249.6 253.9 253.5 246.9 247.3 246.1 243.4 238.8 245.8 248.6 249.6 247.3 250.4 247.5 241.7 240.8 244.8 221.6 241.4 241.8 241.1 230.1 192.1 205.0 221.1 207.6 Less Mine operating costs $m (122.5) (120.9) (121.3) (127.6) (120.5) (115.9) (134.3) (128.3) (139.3) (135.2) (129.0) (140.7) (135.2) (131.1) (133.9) (124.6) (126.7) (134.0) (137.3) (135.3) (129.3) (127.1) (131.1) (131.6) (135.4) (134.5) (131.6) (127.5) (142.0) (131.7) (125.3) (134.9) (139.2) (142.0) (133.9) Recycling credit - including interest income $m 7.9 11.9 15.1 16.7 16.7 15.8 16.4 14.6 14.2 14.4 13.7 13.5 11.8 11.7 12.9 13.2 12.9 13.7 14.0 13.6 13.0 13.1 11.7 11.2 11.3 12.8 11.8 12.2 12.8 11.1 14.0 19.8 19.6 20.7 20.0 Less Royalties $m (11.1) (11.0) (11.9) (13.3) (13.3) (13.4) (13.4) (13.4) (13.4) (13.4) (13.5) (13.5) (13.2) (13.2) (13.1) (13.0) (12.7) (13.1) (13.2) (13.3) (13.2) (13.3) (13.2) (12.9) (12.8) (13.0) (11.8) (12.9) (12.9) (12.8) (12.3) (10.4) (11.0) (11.9) (11.2) Less Production taxes $m (8.1) (8.1) (8.6) (9.4) (9.5) (9.5) (9.5) (9.5) (9.5) (9.5) (9.6) (9.6) (9.4) (9.4) (9.3) (9.2) (9.1) (9.3) (9.4) (9.4) (9.4) (9.5) (9.4) (9.2) (9.2) (9.3) (8.5) (9.2) (9.2) (9.2) (8.9) (7.7) (8.0) (8.6) (8.1) Less Insurance $m (4.1) (4.3) (4.2) (4.2) (4.1) (4.1) (4.1) (4.1) (4.1) (4.1) (4.1) (4.1) (4.1) (4.1) (4.1) (4.1) (4.1) (4.1) (4.1) (4.1) (4.1) (4.1) (4.1) (4.1) (4.1) (4.1) (4.0) (4.0) (4.1) (4.0) (4.5) (5.8) (5.8) (5.8) (5.8) EBITDA $m 69.6 73.2 91.8 109.8 118.0 122.4 104.8 108.9 97.6 101.9 111.4 99.1 97.0 101.2 98.5 105.7 99.1 98.9 98.6 101.1 104.4 109.5 101.4 95.1 90.6 96.7 77.5 100.1 86.6 94.4 93.1 53.2 60.6 73.6 68.5 Less Closure Costs $m - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Net Income (loss) before incom e taxes $m 69.6 73.2 91.8 109.8 118.0 122.4 104.8 108.9 97.6 101.9 111.4 99.1 97.0 101.2 98.5 105.7 99.1 98.9 98.6 101.1 104.4 109.5 101.4 95.1 90.6 96.7 77.5 100.1 86.6 94.4 93.1 53.2 60.6 73.6 68.5 Less 24.37% Income Tax $m (17.0) (17.8) (22.4) (26.8) (28.8) (29.8) (25.5) (26.5) (23.8) (24.8) (27.1) (24.1) (23.6) (24.7) (24.0) (25.8) (24.2) (24.1) (24.0) (24.6) (25.4) (26.7) (24.7) (23.2) (22.1) (23.6) (18.9) (24.4) (21.1) (23.0) (22.7) (13.0) (14.8) (17.9) (16.7) Net Income (loss) $m 52.6 55.3 69.4 83.0 89.2 92.5 79.3 82.4 73.8 77.0 84.2 74.9 73.3 76.5 74.5 80.0 75.0 74.8 74.6 76.5 78.9 82.8 76.7 71.9 68.6 73.1 58.6 75.7 65.5 71.4 70.4 40.2 45.9 55.6 51.8 Less Capital Expenditure $m (47.2) (70.2) (73.5) (61.6) (72.3) (47.8) (42.0) (39.8) (30.7) (34.5) (47.2) (38.4) (28.5) (36.1) (31.8) (79.2) (71.8) (58.7) (56.0) (42.4) (52.0) (51.5) (47.6) (41.8) (39.2) (40.5) (41.2) (46.1) (36.1) (43.1) (51.5) (56.5) (46.1) (41.1) (47.2) NeT Cash Flow $m 5.4 (14.8) (4.0) 21.4 17.0 44.7 37.3 42.6 43.1 42.5 37.0 36.5 44.8 40.5 42.7 0.7 3.1 16.1 18.6 34.1 26.9 31.3 29.1 30.1 29.3 32.6 17.4 29.6 29.3 28.3 18.9 (16.3) (0.3) 14.6 4.7 Cumulative Cash Flow $m 5.4 (14.8) (4.0) 21.4 17.0 44.7 37.3 42.6 43.1 42.5 37.0 36.5 44.8 40.5 42.7 0.7 3.1 16.1 18.6 34.1 26.9 31.3 29.1 30.1 29.3 32.6 17.4 29.6 29.3 28.3 18.9 (16.3) (0.3) 14.6 4.7 East Boulder After Tax NPV5% $m 448.1 Stillwater Mine 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 Palladium ounces produced 214,003 214,146 266,220 307,925 351,477 378,644 386,356 398,591 394,262 388,655 383,253 386,596 385,079 382,450 378,062 380,784 382,659 368,019 366,179 380,098 384,414 379,675 370,183 373,314 369,934 380,008 376,058 410,913 393,746 418,941 179,284 - - - - Platinum ounces produced 62,550 62,591 77,812 90,001 102,731 110,672 112,926 116,502 115,236 113,597 112,019 112,996 112,552 111,784 110,501 111,297 111,845 107,566 107,028 111,097 112,358 110,973 108,199 109,114 108,126 111,070 109,916 120,103 115,086 122,450 52,402 - - - - Com bined ounces produced 276,553 276,737 344,032 397,926 454,208 489,316 499,282 515,092 509,499 502,252 495,272 499,592 497,632 494,234 488,564 492,081 494,504 475,585 473,207 491,195 496,772 490,648 478,382 482,427 478,060 491,078 485,974 531,017 508,832 541,390 231,686 - - - - Palladium revenues $m 267.5 267.7 332.8 384.9 439.3 473.3 482.9 498.2 492.8 485.8 479.1 483.2 481.3 478.1 472.6 476.0 478.3 460.0 457.7 475.1 480.5 474.6 462.7 466.6 462.4 475.0 470.1 513.6 492.2 523.7 224.1 - - - - Platinum revenues $m 78.2 78.2 97.3 112.5 128.4 138.3 141.2 145.6 144.0 142.0 140.0 141.2 140.7 139.7 138.1 139.1 139.8 134.5 133.8 138.9 140.4 138.7 135.2 136.4 135.2 138.8 137.4 150.1 143.9 153.1 65.5 - - - - Gross Revenues $m 345.7 345.9 430.0 497.4 567.8 611.6 624.1 643.9 636.9 627.8 619.1 624.5 622.0 617.8 610.7 615.1 618.1 594.5 591.5 614.0 621.0 613.3 598.0 603.0 597.6 613.8 607.5 663.8 636.0 676.7 289.6 - - - - Less Smelting, refining & transportation $m (32.6) (34.6) (36.1) (36.9) (39.7) (41.2) (41.6) (41.9) (41.9) (41.7) (41.8) (41.4) (41.8) (41.6) (41.6) (41.3) (41.3) (41.0) (40.7) (40.8) (41.0) (41.0) (40.8) (41.1) (41.1) (41.4) (42.2) (42.0) (41.5) (41.3) (24.4) - - - - Net Smelting Returns $m 313.1 311.4 394.0 460.5 528.1 570.4 582.5 602.0 595.0 586.1 577.3 583.1 580.2 576.2 569.1 573.8 576.8 553.5 550.8 573.2 579.9 572.3 557.2 562.0 556.5 572.5 565.3 621.8 594.5 635.5 265.2 - - - - Less Mine operating costs $m (212.2) (207.2) (242.1) (244.0) (271.5) (290.3) (273.7) (284.3) (291.7) (287.9) (309.4) (313.8) (302.8) (311.6) (309.7) (299.6) (300.4) (303.7) (307.0) (306.8) (308.5) (300.8) (295.6) (277.7) (285.8) (232.5) (229.7) (232.7) (227.1) (220.2) (91.7) - - - - Recycling credit - including interest income $m 11.8 17.8 26.4 30.7 35.0 35.7 37.9 34.7 33.4 33.5 30.8 30.6 27.6 26.8 29.5 30.7 30.7 30.4 30.7 30.7 30.0 29.4 25.9 25.6 25.8 29.6 29.8 31.0 31.1 28.7 15.6 - - - - Less Royalties $m (13.3) (13.3) (16.8) (19.6) (22.5) (24.2) (24.8) (25.5) (25.2) (24.8) (24.5) (24.7) (24.5) (24.4) (24.1) (24.3) (24.5) (23.5) (23.4) (24.3) (24.6) (24.2) (23.5) (23.7) (23.5) (24.3) (24.0) (26.3) (25.2) (26.8) (11.2) - - - - Less Production taxes $m (13.1) (13.1) (15.8) (18.0) (20.3) (21.6) (22.1) (22.6) (22.4) (22.1) (21.8) (22.0) (21.9) (21.7) (21.6) (21.7) (21.8) (21.1) (21.0) (21.7) (21.9) (21.7) (21.1) (21.3) (21.1) (21.7) (21.4) (23.3) (22.4) (23.7) (11.5) - - - - Less Insurance $m (7.8) (8.3) (8.4) (8.4) (8.5) (8.5) (8.5) (8.6) (8.6) (8.5) (8.5) (8.5) (8.5) (8.5) (8.5) (8.5) (8.6) (8.5) (8.5) (8.5) (8.5) (8.5) (8.5) (8.5) (8.5) (8.5) (8.6) (8.6) (8.6) (8.6) (8.1) - - - - EBITDA $m 78.3 87.4 137.3 201.2 240.4 261.4 291.3 295.7 280.6 276.2 243.9 244.7 250.0 236.8 234.7 250.2 252.3 227.2 221.6 242.5 246.4 246.5 234.3 256.4 243.3 315.1 311.4 361.9 342.3 384.9 158.3 - - - - Less Closure Costs $m - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - (22.8) (22.8) (11.4) - Net Income (loss) before incom e taxes $m 78.3 87.4 137.3 201.2 240.4 261.4 291.3 295.7 280.6 276.2 243.9 244.7 250.0 236.8 234.7 250.2 252.3 227.2 221.6 242.5 246.4 246.5 234.3 256.4 243.3 315.1 311.4 361.9 342.3 384.9 158.3 (22.8) (22.8) (11.4) (0.0) Less 24.37% Income Tax % $m (19.1) (21.3) (33.5) (49.0) (58.6) (63.7) (71.0) (72.1) (68.4) (67.3) (59.4) (59.6) (60.9) (57.7) (57.2) (61.0) (61.5) (55.4) (54.0) (59.1) (60.0) (60.1) (57.1) (62.5) (59.3) (76.8) (75.9) (88.2) (83.4) (93.8) (38.6) - - - - Net Income (loss) $m 59.2 66.1 103.9 152.1 181.8 197.7 220.3 223.6 212.2 208.9 184.5 185.1 189.1 179.1 177.5 189.3 190.8 171.8 167.6 183.4 186.3 186.5 177.2 193.9 184.0 238.3 235.5 273.7 258.9 291.1 119.7 (22.8) (22.8) (11.4) (0.0) Less Capital Expenditure $m (111.6) (172.1) (190.6) (166.2) (112.1) (147.3) (162.1) (169.0) (130.3) (121.3) (92.9) (77.4) (88.3) (78.7) (76.5) (84.0) (93.4) (77.5) (63.2) (60.5) (48.9) (52.5) (52.6) (54.3) (44.8) (33.2) (30.9) (22.6) (13.2) (15.5) (10.9) - - - - Net Cash Flow $m (52.3) (106.0) (86.8) (14.1) 69.7 50.4 58.2 54.6 81.9 87.6 91.6 107.6 100.8 100.3 101.0 105.2 97.5 94.3 104.4 122.9 137.4 133.9 124.7 139.5 139.2 205.1 204.6 251.0 245.7 275.6 108.8 (22.8) (22.8) (11.4) (0.0) Cumulative Cash Flow $m (52.3) (158.3) (245.1) (259.2) (189.4) (139.1) (80.9) (26.2) 55.6 143.3 234.8 342.5 443.2 543.6 644.5 749.7 847.2 941.6 1,045.9 1,168.9 1,306.3 1,440.2 1,564.9 1,704.4 1,843.7 2,048.7 2,253.3 2,504.3 2,750.1 3,025.6 3,134.5 3,111.7 3,088.9 3,077.5 3,077.5 Stillwater After Tax NPV5% $m 1,060.9 Combined Mines 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 Palladium ounces produced 357,601 357,705 418,482 475,999 519,552 546,719 554,431 566,665 562,337 556,729 553,886 557,433 551,390 549,135 543,945 545,356 544,308 534,177 534,301 549,043 551,745 548,900 537,695 536,935 532,917 545,317 525,980 573,931 557,236 581,864 340,734 148,792 157,021 167,276 158,651 Platinum ounces produced 103,718 103,749 121,465 138,187 150,917 158,858 161,112 164,688 163,422 161,783 160,938 161,974 160,233 159,572 158,059 158,479 158,189 155,202 155,228 159,532 160,331 159,489 156,223 156,023 154,852 158,463 152,897 166,840 161,957 169,159 98,689 42,658 45,017 47,957 45,484 Com bined ounces produced 461,319 461,453 539,947 614,186 670,469 705,576 715,542 731,353 725,759 718,512 714,824 719,407 711,623 708,707 702,004 703,834 702,497 689,379 689,528 708,575 712,076 708,389 693,918 692,958 687,769 703,780 678,877 740,771 719,193 751,023 439,422 191,450 202,039 215,233 204,135 Palladium revenues $m 447.0 447.1 523.1 595.0 649.4 683.4 693.0 708.3 702.9 695.9 692.4 696.8 689.2 686.4 679.9 681.7 680.4 667.7 667.9 686.3 689.7 686.1 672.1 671.2 666.1 681.6 657.5 717.4 696.5 727.3 425.9 186.0 196.3 209.1 198.3 Platinum revenues $m 129.6 129.7 151.8 172.7 188.6 198.6 201.4 205.9 204.3 202.2 201.2 202.5 200.3 199.5 197.6 198.1 197.7 194.0 194.0 199.4 200.4 199.4 195.3 195.0 193.6 198.1 191.1 208.5 202.4 211.4 123.4 53.3 56.3 59.9 56.9 Gross Revenues $m 576.6 576.8 674.9 767.7 838.1 882.0 894.4 914.2 907.2 898.1 893.5 899.3 889.5 885.9 877.5 879.8 878.1 861.7 861.9 885.7 890.1 885.5 867.4 866.2 859.7 879.7 848.6 926.0 899.0 938.8 549.3 239.3 252.5 269.0 255.2 Less Smelting, refining & transportation $m (56.1) (59.9) (58.2) (59.6) (61.2) (62.1) (62.3) (62.6) (62.5) (62.5) (62.3) (62.7) (62.4) (62.4) (62.3) (62.5) (62.5) (62.4) (62.5) (62.9) (62.8) (62.8) (62.7) (62.6) (62.4) (62.5) (61.7) (62.8) (62.6) (62.2) (54.0) (47.2) (47.5) (48.0) (47.6) Net Smelting Returns $m 520.6 516.9 616.8 708.1 776.9 819.9 832.1 851.6 844.7 835.7 831.3 836.6 827.2 823.5 815.2 817.3 815.6 799.3 799.4 822.8 827.3 822.7 804.7 803.6 797.3 817.3 786.9 863.2 836.4 876.6 495.3 192.1 205.0 221.1 207.6 Less Mine operating costs $m (334.7) (328.1) (363.4) (371.7) (392.0) (406.1) (407.9) (412.6) (431.1) (423.1) (438.3) (454.5) (438.0) (442.7) (443.7) (424.3) (427.1) (437.7) (444.2) (442.1) (437.8) (427.8) (426.8) (409.3) (421.2) (367.0) (361.2) (360.2) (369.0) (351.9) (217.0) (134.9) (139.2) (142.0) (133.9) Recycling credit - including interest income $m 19.7 29.7 41.5 47.4 51.6 51.4 54.3 49.3 47.6 47.9 44.5 44.1 39.4 38.5 42.4 43.8 43.7 44.1 44.7 44.3 42.9 42.5 37.6 36.8 37.1 42.4 41.7 43.2 43.9 39.8 29.5 19.8 19.6 20.7 20.0 Less Royalties $m (24.5) (24.3) (28.7) (32.9) (35.8) (37.6) (38.2) (38.9) (38.6) (38.2) (38.0) (38.2) (37.7) (37.5) (37.2) (37.3) (37.2) (36.6) (36.6) (37.6) (37.7) (37.6) (36.7) (36.6) (36.3) (37.3) (35.8) (39.2) (38.1) (39.7) (23.6) (10.4) (11.0) (11.9) (11.2) Less Production taxes $m (21.3) (21.1) (24.4) (27.4) (29.7) (31.1) (31.6) (32.1) (31.9) (31.6) (31.4) (31.6) (31.2) (31.1) (30.9) (31.0) (30.9) (30.4) (30.4) (31.1) (31.3) (31.1) (30.5) (30.4) (30.2) (31.0) (30.0) (32.5) (31.6) (32.8) (20.4) (7.7) (8.0) (8.6) (8.1) Less Insurance $m (11.9) (12.6) (12.6) (12.6) (12.6) (12.6) (12.6) (12.6) (12.6) (12.6) (12.6) (12.6) (12.6) (12.6) (12.6) (12.6) (12.6) (12.6) (12.6) (12.6) (12.6) (12.6) (12.6) (12.6) (12.6) (12.6) (12.6) (12.6) (12.6) (12.6) (12.6) (5.8) (5.8) (5.8) (5.8) EBITDA $m 147.9 160.6 229.1 311.0 358.4 383.8 396.1 404.7 378.1 378.1 355.3 343.8 347.0 338.0 333.2 356.0 351.4 326.1 320.2 343.6 350.7 356.0 335.7 351.4 334.0 411.7 388.9 461.9 428.9 479.3 251.3 53.2 60.6 73.6 68.5 Less Closure Costs $m - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - (22.8) (22.8) (11.4) - Net Income (loss) before incom e taxes $m 147.9 160.6 229.1 311.0 358.4 383.8 396.1 404.7 378.1 378.1 355.3 343.8 347.0 338.0 333.2 356.0 351.4 326.1 320.2 343.6 350.7 356.0 335.7 351.4 334.0 411.7 388.9 461.9 428.9 479.3 251.3 30.4 37.8 62.2 68.5 Less 24.37% Income Tax % $m (36.0) (39.1) (55.8) (75.8) (87.3) (93.5) (96.5) (98.6) (92.2) (92.1) (86.6) (83.8) (84.6) (82.4) (81.2) (86.7) (85.6) (79.5) (78.0) (83.7) (85.5) (86.8) (81.8) (85.6) (81.4) (100.3) (94.8) (112.6) (104.5) (116.8) (61.3) (7.4) (9.2) (15.1) (16.7) Net Income (loss) $m 111.9 121.4 173.3 235.2 271.1 290.3 299.6 306.0 286.0 285.9 268.7 260.0 262.4 255.6 252.0 269.2 265.8 246.6 242.2 259.9 265.3 269.2 253.9 265.8 252.6 311.4 294.1 349.4 324.4 362.5 190.1 23.0 28.6 47.0 51.8 Less Capital Expenditure $m (158.8) (242.3) (264.1) (227.8) (184.3) (195.2) (204.1) (208.8) (161.0) (155.8) (140.1) (115.9) (116.9) (114.8) (108.3) (163.2) (165.2) (136.2) (119.2) (102.9) (101.0) (104.0) (100.2) (96.1) (84.0) (73.7) (72.1) (68.8) (49.3) (58.6) (62.3) (56.5) (46.1) (41.1) (47.2) Net Cash Flow $m (46.9) (120.9) (90.8) 7.4 86.7 95.1 95.4 97.3 125.0 130.1 128.6 144.1 145.6 140.8 143.7 106.0 100.6 110.4 123.0 157.0 164.3 165.2 153.7 169.7 168.6 237.7 222.0 280.6 275.1 303.9 127.8 (33.5) (17.5) 6.0 4.7 Cumulative Cash Flow $m (46.9) (167.7) (258.6) (251.2) (164.5) (69.4) 26.0 123.3 248.3 378.4 507.0 651.2 796.7 937.5 1,081.2 1,187.2 1,287.8 1,398.3 1,521.2 1,678.2 1,842.5 2,007.7 2,161.4 2,331.1 2,499.7 2,737.4 2,959.4 3,240.0 3,515.1 3,819.0 3,946.7 3,913.2 3,895.7 3,901.6 3,906.3 Com bined After Tax NPV5% $m 1,511.7


295 East Boulder Mine 2059 2060 2061 2062 2063 2064 2065 2066 2067 2068 2069 2070 2071 2072 2073 2074 2075 Palladium ounces produced 166,552 165,482 166,535 164,262 163,240 167,056 166,088 166,862 164,255 165,992 94,538 - - - - - - Platinum ounces produced 47,750 47,443 47,745 47,093 46,800 47,894 47,616 47,838 47,091 47,589 27,103 - - - - - - Combined ounces produced 214,302 212,925 214,280 211,355 210,040 214,951 213,704 214,700 211,346 213,581 121,641 - - - - - - Palladium revenues $m 208.2 206.9 208.2 205.3 204.1 208.8 207.6 208.6 205.3 207.5 118.2 - - - - - - Platinum revenues $m 59.7 59.3 59.7 58.9 58.5 59.9 59.5 59.8 58.9 59.5 33.9 - - - - - - Gross Revenues $m 267.9 266.2 267.8 264.2 262.6 268.7 267.1 268.4 264.2 267.0 152.1 - - - - - - Less Smelting, ref ining & transportation $m (47.8) (47.6) (47.7) (47.6) (47.4) (47.8) (48.0) (48.1) (48.0) (48.2) (44.9) - - - - - - Net Smelting Returns $m 220.1 218.6 220.2 216.6 215.1 220.9 219.1 220.2 216.2 218.8 107.2 - - - - - - Less Mine operating costs $m (137.1) (126.2) (131.7) (133.8) (125.7) (129.2) (131.3) (131.4) (117.1) (112.5) (83.7) - - - - - - Recycling credit - including interest income $m 20.6 20.6 20.7 20.5 20.3 20.7 20.7 20.8 20.5 20.7 13.5 - - - - - - Less Royalties $m (11.8) (11.7) (11.8) (11.6) (11.6) (11.9) (11.8) (11.8) (11.6) (11.7) (5.8) - - - - - - Less Production taxes $m (8.5) (8.5) (8.6) (8.4) (8.4) (8.6) (8.5) (8.5) (8.4) (8.5) (4.9) - - - - - - Less Insurance $m (5.8) (5.8) (5.8) (5.8) (5.8) (5.8) (5.8) (5.8) (5.8) (5.8) (5.8) - - - - - - EBITDA $m 77.5 86.9 83.0 77.4 84.0 86.2 82.5 83.5 93.8 101.0 20.5 - - - - - - Less Closure Costs $m - - - - - - - - - - - (13.8) (13.8) (6.9) - - - Net Income (loss) before income taxes $m 77.5 86.9 83.0 77.4 84.0 86.2 82.5 83.5 93.8 101.0 20.5 (13.8) (13.8) (6.9) - - - Less 24.37% Income Tax $m (18.9) (21.2) (20.2) (18.9) (20.5) (21.0) (20.1) (20.3) (22.9) (24.6) (5.0) - - - - - - Net Income (loss) $m 58.6 65.7 62.8 58.5 63.5 65.2 62.4 63.1 71.0 76.4 15.5 (13.8) (13.8) (6.9) - - - Less Capital Expenditure $m (33.9) (33.0) (16.8) (11.6) (15.8) (11.9) (16.5) (7.2) (5.7) (5.7) (5.7) - - - - - - NeT Cash Flow $m 24.7 32.7 46.0 46.9 47.7 53.3 45.9 56.0 65.2 70.8 9.8 (13.8) (13.8) (6.9) - - - Cumulative Cash Flow $m 24.7 32.7 46.0 46.9 47.7 53.3 45.9 56.0 65.2 70.8 9.8 (13.8) (13.8) (6.9) - - - East Boulder After Tax NPV5% $m 448.1 Stillwater Mine 2059 2060 2061 2062 2063 2064 2065 2066 2067 2068 2069 2070 2071 2072 2073 2074 2075 Palladium ounces produced - - - - - - - - - - - - - - - - - Platinum ounces produced - - - - - - - - - - - - - - - - - Combined ounces produced - - - - - - - - - - - - - - - - - Palladium revenues $m - - - - - - - - - - - - - - - - - Platinum revenues $m - - - - - - - - - - - - - - - - - Gross Revenues $m - - - - - - - - - - - - - - - - - Less Smelting, ref ining & transportation $m - - - - - - - - - - - - - - - - - Net Smelting Returns $m - - - - - - - - - - - - - - - - - Less Mine operating costs $m - - - - - - - - - - - - - - - - - Recycling credit - including interest income $m - - - - - - - - - - - - - - - - - Less Royalties $m - - - - - - - - - - - - - - - - - Less Production taxes $m - - - - - - - - - - - - - - - - - Less Insurance $m - - - - - - - - - - - - - - - - - EBITDA $m - - - - - - - - - - - - - - - - - Less Closure Costs $m - - - - - - - - - - - - - - - - - Net Income (loss) before income taxes $m - - - - - - - - - - - - - - - - - Less 24.37% Income Tax % $m - - - - - - - - - - - - - - - - - Net Income (loss) $m - - - - - - - - - - - - - - - - - Less Capital Expenditure $m - - - - - - - - - - - - - - - - - Net Cash Flow $m - - - - - - - - - - - - - - - - - Cumulative Cash Flow $m 3,077.5 3,077.5 3,077.5 3,077.5 3,077.5 3,077.5 3,077.5 3,077.5 3,077.5 3,077.5 3,077.5 3,077.5 3,077.5 3,077.5 3,077.5 3,077.5 3,077.5 Stillwater After Tax NPV5% $m 1,060.9 Combined Mines 2059 2060 2061 2062 2063 2064 2065 2066 2067 2068 2069 2070 2071 2072 2073 2074 2075 Palladium ounces produced 166,552 165,482 166,535 164,262 163,240 167,056 166,088 166,862 164,255 165,992 94,538 - - - - - - Platinum ounces produced 47,750 47,443 47,745 47,093 46,800 47,894 47,616 47,838 47,091 47,589 27,103 - - - - - - Combined ounces produced 214,302 212,925 214,280 211,355 210,040 214,951 213,704 214,700 211,346 213,581 121,641 - - - - - - Palladium revenues $m 208.2 206.9 208.2 205.3 204.1 208.8 207.6 208.6 205.3 207.5 118.2 - - - - - - Platinum revenues $m 59.7 59.3 59.7 58.9 58.5 59.9 59.5 59.8 58.9 59.5 33.9 - - - - - - Gross Revenues $m 267.9 266.2 267.8 264.2 262.6 268.7 267.1 268.4 264.2 267.0 152.1 - - - - - - Less Smelting, ref ining & transportation $m (47.8) (47.6) (47.7) (47.6) (47.4) (47.8) (48.0) (48.1) (48.0) (48.2) (44.9) - - - - - - Net Smelting Returns $m 220.1 218.6 220.2 216.6 215.1 220.9 219.1 220.2 216.2 218.8 107.2 - - - - - - Less Mine operating costs $m (137.1) (126.2) (131.7) (133.8) (125.7) (129.2) (131.3) (131.4) (117.1) (112.5) (83.7) - - - - - - Recycling credit - including interest income $m 20.6 20.6 20.7 20.5 20.3 20.7 20.7 20.8 20.5 20.7 13.5 - - - - - - Less Royalties $m (11.8) (11.7) (11.8) (11.6) (11.6) (11.9) (11.8) (11.8) (11.6) (11.7) (5.8) - - - - - - Less Production taxes $m (8.5) (8.5) (8.6) (8.4) (8.4) (8.6) (8.5) (8.5) (8.4) (8.5) (4.9) - - - - - - Less Insurance $m (5.8) (5.8) (5.8) (5.8) (5.8) (5.8) (5.8) (5.8) (5.8) (5.8) (5.8) - - - - - - EBITDA $m 77.5 86.9 83.0 77.4 84.0 86.2 82.5 83.5 93.8 101.0 20.5 - - - - - - Less Closure Costs $m - - - - - - - - - - - (13.8) (13.8) (6.9) - - - Net Income (loss) before income taxes $m 77.5 86.9 83.0 77.4 84.0 86.2 82.5 83.5 93.8 101.0 20.5 (13.8) (13.8) (6.9) - - - Less 24.37% Income Tax % $m (18.9) (21.2) (20.2) (18.9) (20.5) (21.0) (20.1) (20.3) (22.9) (24.6) (5.0) - - - - - - Net Income (loss) $m 58.6 65.7 62.8 58.5 63.5 65.2 62.4 63.1 71.0 76.4 15.5 (13.8) (13.8) (6.9) - - - Less Capital Expenditure $m (33.9) (33.0) (16.8) (11.6) (15.8) (11.9) (16.5) (7.2) (5.7) (5.7) (5.7) - - - - - - Net Cash Flow $m 24.7 32.7 46.0 46.9 47.7 53.3 45.9 56.0 65.2 70.8 9.8 (13.8) (13.8) (6.9) - - - Cumulative Cash Flow $m 3,931.0 3,963.7 4,009.7 4,056.6 4,104.3 4,157.6 4,203.5 4,259.5 4,324.7 4,395.4 4,405.3 4,391.5 4,377.7 4,370.8 4,370.8 4,370.8 4,370.8 Combined After Tax NPV5% $m 1,511.7 296 Net Present Values The post-tax cash flows for Stillwater and East Boulder Mines derive the DCF results contained in Table 70, which illustrate the discount rate sensitivity of these mines and the overall Sibanye-Stillwater US PGM Operations. Table 70: Net Present Values at Different Discount Rates Description of Mineral Asset Parameter Unit Real Discount Rate 0.00% 2.50% 5.00% 7.50% East Boulder Mine NPV $ million 1 279 717 448 305 Stillwater Mine NPV $ million 3 077 1 785 1 061 640 Sibanye-Stillwater US PGM Operations NPV $ million 4 371 2 508 1 512 946 Internal Rate of Return The Internal Rate of Return (IRR) of the Sibanye-Stillwater US PGM Operations is 27%. Sensitivity Analysis Sensitivity analyses of the NPVs at the real discount rate of 5% (NPV5%) for variation in grade, revenue, capital and operating costs in the range ±10% for Stillwater and East Boulder Mines are illustrated in Figure 82 and Figure 83, respectively. In each case, the NPV result is most sensitive to revenue and less sensitive to operating cost and capital cost variation. Figure 82: Stillwater Mine NPV Sensitivity Analysis 297 Figure 83: East Boulder Mine NPV Sensitivity Analysis For the combined Sibanye-Stillwater US PGM Operations, the two-variable sensitivity analysis of the NPV5% to variance in both palladium and platinum price has been completed (with reference to Table 48). These results are illustrated in Table 71. Table 71: Combined Sibanye-Stillwater US PGM Operations, NPV5% Sensitivity to Pd and Pt Price Variation NPV5% $million Palladium Price Variance from Base Assumption Variance -10% -5% 0% 5% 10% Platinum Price Variance from Base Assumption -10% $494 $888 $1 283 $1 677 $2 071 -5% $608 $1 003 $1 397 $1 792 $2 186 0% $723 $1 117 $1 512 $1 906 $2 301 5% $837 $1 232 $1 626 $2 021 $2 415 10% $952 $1 346 $1 741 $2 135 $2 530 The foregoing sensitivity analysis demonstrates robust results over material technical and economic input range variances and at a range of discount rates. This is considered a reasonable and realistic test of economic viability of the LoM plans for Stillwater and East Boulder Mines and the consolidated LoM plan for the Sibanye-Stillwater US PGM Operations. Accordingly, extraction of the scheduled Indicated and Measured Mineral Resources is economically justified while the declaration of Mineral Reserves for Stillwater and East Boulder Mines is appropriate. 298 ADJACENT PROPERTIES Sibanye-Stillwater’s mineral title covers the entire known strike length of the J-M Reef of approximately 28 miles. The J-M Reef is currently the only PGM-bearing layer in the Stillwater Complex that can be economically exploited at the current and expected economic conditions. As a result, only the geological and mining information generated by Sibanye-Stillwater and predecessor companies within the areas for which Sibanye-Stillwater holds title is of relevance to the Mineral Resources and Mineral Reserves for the Stillwater and East Boulder Mines reported in this TRS. Accordingly, there is no relevant adjacent property information to be discussed in this TRS.


299 OTHER RELEVANT DATA AND INFORMATION Catalytic Converter Recycling Business Background As part of the smelting and refining operations, the Sibanye-Stillwater US PGM Operations include a recycling facility for spent automotive catalytic converters at the Columbus Metallurgical Complex. The recycle business is operated on both toll and outright purchase bases dependant on prevailing market conditions. However, under these scenarios, accurate sampling and analysis is critical to the business. The recycled catalytic converters are added to the concentrate from the mines in the electric arc furnace and the contained PGMs are recovered using the copper and nickel in the mine concentrate as collectors. The format of the catalytic converters varies with the origin of the supply. The European market has mostly diesel vehicles which use a silicon carbide substrate and recycle material from this area tend to be higher in carbon content. However, the North American market tends to supply an exclusively palladium containing recycle material. Carbon and silicon carbide are problematic to the smelting process dependant on the levels contained and, therefore, are measured and managed accordingly. Recycle Processing The recycle materials are delivered in bulk bags with a mass and chemical analysis per bag from the supplier but the official mass and analytical measurements are performed by Sibanye-Stillwater US PGM Operations. The bags are stored until the furnace feed recipe allows for processing (based on the contained carbon) and then delivered into the process via the sampling plant. The bags are weighed, and the contents introduced into the sampling plant which produces a bulk sample equivalent to approximately 1.6% of the bulk mass which is then further reduced to produce the final samples for the laboratory analysis. Samples received are ground in a fully automated grinding and blending machine (HPM1500), analysed for carbon using a Leco™ analyser and pulverised. Carbon analysis is performed ahead of any other analysis to ensure that the process critical carbon levels are in line with the levels reported by the customer. This carbon analysis is used to inform the blending and processing of recycle materials to ensure excess carbon is not added into the smelting process. The pulverised material is subjected to preliminary XRF analysis then dual analysis through XRF (Panalytical Energy Dispersive XRF) and PbFA and ICP-OES. The sampled and crushed recycle materials are introduced into the smelting process via a dedicated hopper in the batching plant and are then blended into the primary furnace feed via the computer control system. The copper and nickel in the matte from the mine concentrates act as a collector for the Pd and Pt present in the smelter feed stream originating from both mine concentrates and recycle materials. As such, it is critical that the recycle materials are balanced with the mine concentrates to ensure sufficient collection capacity for the total PGM loading delivered. 300 Recycling Operations The catalyst recycling business forms an integral part of the Columbus Metallurgical Complex processing feedstock but is not relevant to the declaration of Mineral Reserves for Stillwater and East Boulder Mines. However, revenue credits from the recycling business and by-products often exceed the operating cost for the smelting and refining operations, which underscores the importance of these two additional revenue sources to the value of the Sibanye-Stillwater US PGM Operations. 301 INTERPRETATION AND CONCLUSIONS The Qualified Persons have extensively reviewed base geological, mining, ore processing, mineral beneficiation and environmental and permitting information and costs used to estimate the Mineral Resources and Mineral Reserves for the Sibanye-Stillwater US PGM Operations. From the review and participation in the Mineral Resource and Mineral Reserve estimation, the Qualified Persons are satisfied with the integrity of the base data, estimation processes and the final Mineral Resources and Mineral Reserves contained in this report. Below is a summary the Qualified Person’s interpretations and conclusions regarding the Mineral Resources and Mineral Reserves for the Sibanye-Stillwater US PGM Operations. The Sibanye-Stillwater US PGM Operations are well-established mining, ore processing and mineral beneficiation operations located in Montana and producing PGMs from the extraction of the J-M Reef, which is the highest-grade PGM deposit known to exist in the world. Sibanye-Stillwater has title (leased or held Mining Claims) in perpetuity over the entirety of the known outcrop of the J-M Reef along the Beartooth Mountains in Montana. It also holds surface rights (Tunnel and Mill Site Claims) over key land parcels on which mining infrastructure is built both at Stillwater and East Boulder Mines, with the mining complexes comprising underground mining and integrated ore processing infrastructure. The surface rights also provide servitude required to access the reef or to establish and connect surface infrastructure. A network comprising state roads and a Sibanye-Stillwater maintained road connects the mines, local towns and the Columbus Metallurgical Complex where the smelter, base metal refinery, laboratory and PGM catalyst recycling plant are situated. Regional power infrastructure is already installed providing adequate power supplies to the operations. In general, climatic conditions in this area do not significantly affect the operations at the three sites. However, a 500-year flood event in 2022 destroyed parts of State Highway 419 used to access Stillwater Mine and temporary suspension of the mining operations for seven weeks. A temporary road was built to reestablish access to and from the mine for essential shaft maintenance services and limited mining operations. Repairs were carried out on the damaged parts of the highway and access was restored in July 2023. Inclement weather in the form of heavy snow has temporarily restricted mine access, with no major impact on the operations, as snow removal and road maintenance have been adequate to quickly restore access. Whereas the regulatory framework for mining provides for a simplified system for obtaining and maintaining mining and surface title, the granting of permits and approvals for building a mine or expansions to existing mining operations is costly and can be a lengthy process. The 24-year-old Good Neighbor Agreement between Sibanye-Stillwater and the local authorities has facilitated seamless stakeholder participation in the scoping and review of applications for permits and approvals. Extensive exploration work spanning several decades and dominated by diamond drilling at Stillwater and East Boulder Mines produced data utilised for the evaluation of the J-M Reef. The J-M Reef is a world class magmatic reef-type PGM deposit in the geologically favourable Stillwater Complex. The extensive drillhole database accumulated from moderately spaced surface diamond drilling and closely spaced underground definition diamond drilling from footwall lateral drifts, complemented by 302 mining and ore processing information, has confirmed the presence and character of the Pd-Pt dominant mineralisation in the J-M Reef. The drilling strategy adopted is a consequence of the rugged terrain characterising the Beartooth Mountain area, the steep dips of the J-M Reef and high localised variability in the J-M Reef. The approaches employed for the collection, validation, processing and interpretation of drillhole data are in line with industry best practice. The extensive validated drillhole database forms the basis for the Mineral Resource estimates reported for Stillwater and East Boulder Mines. The combination of long-range continuity, occurrence at a consistent stratigraphic position and within a consistent stratigraphic sequence, localised thickness and grade variability and steep dips influences the drilling strategy and estimation approaches employed for the J-M Reef. Available data permitted the construction of 3D geological models and estimation of grades in areas supported by surface exploration and definition drillhole data classified as Measured and the remainder of the areas supported by surface drillhole data classified as Indicated or Inferred after consideration of geological confidence and knowledge. The estimation approaches are appropriate for the style and variability of the J-M Reef. The reporting of the Mineral Resources at the minimum mining width based on the dominant mechanised ramp and rill method used and 2E cut-off grade is well-reasoned. Detailed LoM plans for Stillwater and East Boulder Mines support the Mineral Reserve estimates reported by Sibanye-Stillwater for the Sibanye-Stillwater US PGM Operations. Modifying factors derived through reconciliation at the mines have been utilised for the conversion of Indicated and Measured Mineral Resources to Probable and Proven Mineral Reserves, respectively. The mechanised ramp and fill method, which is the dominant mining method, is well-understood at the mines and suited to the character and attitude of the J-M Reef. Mine designs for Stillwater and East Boulder Mines incorporate the hydrogeological and geotechnical models constructed from groundwater and geotechnical testwork, an extensive geotechnical database and historical experience at the mines. Ground support designs and procedures employed at the mines, which have been refined through ongoing continuous improvement initiatives, have minimised occurrences of major fall of ground occurrences. A higher- than-expected frequency of poor ground conditions at the Stillwater East Section has necessitated a revision of the mining plan, with fair and good ground types prioritised in the short to medium terms until a dedicated sand paste plant has been established in this area which would enable improved mining efficiencies when mining in areas of poor ground conditions. No significant groundwater inflows are experienced except when development extends into new areas, but these are addressed using existing procedures combining probe drilling, the use of drainholes and routine mine dewatering using cascading water pumps. The LoM production plans for Stillwater and East Boulder Mines were developed through a Mineral Resources to Mineral Reserve conversion process which utilised dilution factors and mining parameters informed by historical reconciliation results and performance. The use of factors aligned to historical performance enhances the achievability of the plans. The LoM plans envisage an important ore production tonnage ramp up at Stillwater Mine associated with the Stillwater East Section. The COVID- 19 pandemic restrictions, a 500-year flood event in FY2022 and a shaft incident in FY2023 interrupted the ramp up momentum. The LoM plan for East Boulder Mine envisages modest changes to production but the production levels are aligned with historical production levels after the implementation of the Fill The Mill Project. The COVID-19 pandemic restrictions as well technical staff turnover affected production


303 output in FY2022. The LoM plans for Stillwater and East Boulder Mines were subjected to economic viability testing to demonstrate that extraction of the scheduled Indicated and Measured Mineral Resources is economically justified. Furthermore, most of the key infrastructure for mining is already installed at the Stillwater and East Boulder Mines. Similarly, most of the mining equipment required for the execution of the plans is available at the mines. Bulk power and water supplies are secure, and the infrastructure upgrades required have been completed ahead of the achievement of steady state production levels. The concentrators employed for ore processing at Stillwater and East Boulder Mines have been operational for several decades and use proven technology and process routes. Furthermore, the forecast metallurgical recoveries and production profiles employed in the LoM plans are informed by historical experience. A recent concentrator capacity upgrade at Stillwater Mine accommodates increasing RoM ore production from the Stillwater East Section until FY2028. Further upgrades of the flotation cell capacity prior to FY2029 will eliminate the bottleneck in this area which is restricting plant capacity to below the planned steady state production levels. The LoM plan for East Boulder Mine benefits from surplus concentrator capacity. There is adequate storage capacity for the tailings resulting from ore processing at the concentrators at both Stillwater and East Boulder Mines in the short to medium terms. However, additional tailings storage capacity will be required for the remainder of the LoMs. Plans being considered for the upgrading the TSF capacities for the long-term disposal of the tailings include storage capacity upgrades at existing TSFs through elevation lifts and lateral expansions as well as the establishment of new TSFs. Sibanye-Stillwater is aware of the long timeframes for the granting of permits and related approvals of the upgrades and establishment of new TSFs. As a result, it will expedite the finalisation of the long-term tailings storage plans required to enable the undertaking of the requisite studies needed for permit and approval applications. The smelter and base metal refinery at the Columbus Metallurgical Complex utilise proven technology and process routes for the processing of concentrate and matte, respectively. There are no plans to introduce new processing technology at the processing facilities. Modest capacity upgrades and debottlenecking projects implemented to accommodate increased concentrate production from the Stillwater and East Boulder Mines have been concluded, with the bottleneck in the flotation circuits at the Stillwater Concentrator being the exception. The LoM plans for Stillwater and East Boulder Mines and the Columbus Metallurgical Complex provide for appropriate capital expenditure budgets for the sustainability of the operations and for the various capacity upgrades and production expansions envisaged. Sustaining capital costs are benchmarked to historical capital expenditure. Similarly, the forecast operating costs included in the LoM plans are based on actual costs at the operations, with adjustments made for escalation as required. The importance of the catalyst recycling business and by-products to the Sibanye-Stillwater US PGM Operations is manifested by revenue credits from these sources that often exceed the operating cost for the smelting and refining operations at the Columbus Metallurgical Complex. However, the recycling 304 business and the by-products are excluded from the Mineral Resources and Mineral Reserves for Stillwater and East Boulder Mines. Sibanye-Stillwater has all necessary rights and approvals to operate the mines, concentrators, TSFs, waste rock storage dumps, smelter and ancillary facilities associated with the Sibanye-Stillwater US PGM Operations. Appropriate additional studies, designs and permitting documents have been or are in the process of being completed to support the planned operational expansions. Current permit and license violations are being corrected and environmental impacts are being managed in close consultation with the appropriate agencies. There are reasonable prospects that the operator’s licence to operate on these premises is secure for the foreseeable future, unless terminated by regulatory authorities for other reasons. Bonding amounts are deemed reasonable and appropriate for the permitted activities and obligations at both Stillwater and East Boulder Mines. Furthermore, based on assessment of the current permits, technical submittals, regulatory requirements and project compliance history, continued acquisition of permit approvals should be possible and there is low risk of rejections of permit applications by the regulatory for the foreseeable future. The prevailing market fundamentals for palladium and platinum are forecast to remain in place in the foreseeable future and the price forecasts and other economic assumptions utilised for economic viability testing of the LoM plans are reasonable. Sibanye-Stillwater’s risk management process has identified various material risks to LoM plans and Mineral Reserves relating to geotechnical and geohydrological uncertainties, inability to execute LoM plans, metal price downturns, inadequate tailings storage capacity, unplanned production cost escalation, unplanned power outages and restricted access to the operations caused by extreme weather events. Sibanye-Stillwater has mitigated (and not eliminated) these risks as per its risk management protocols to reduce the likelihood of occurrence and/or impact when the risk occurs which resulted in a reclassification of the residual risks as low to medium risks. The Qualified Persons consider the risk management process robust and sufficient to identify material risks that should be mitigated to enhance the achievability of the LoM plans. From their appraisal of the residual risks after mitigation, the Qualified Persons could not identify any unmitigated material risks to the LoM plans and Mineral Reserves associated with the modifying factors or resulting from changes to any aspect of the modifying factors. The Qualified Persons could not identify any residual material risks that would affect the Mineral Resources and Mineral Reserves reported for Stillwater and East Boulder Mines or the projected economic outcomes. Sibanye-Stillwater is fully aware of the low to medium risks identified and have mitigation measures in place to minimise the impact of the risks on the mining, ore processing and mineral beneficiation operations in Montana. 305 RECOMMENDATIONS The Qualified Persons recommend further upgrades to the flotation circuits at the Stillwater Concentrator to increase plant capacity from 3 400 tons to 4 110 ton per day (i.e. 1.1 million tons to 1.4 million tons per year at 92% utilisation) prior to FY2029 when production targets set out in the LoM plan exceed the current 1.1-million-toncapacity. Mechanical equipment needed for the flotation circuit upgrades has already been procured as part of the Blitz Project. Sibanye-Stillwater has undertaken to complete this work at an additional cost of approximately $1.8 million (labour cost) a year before the capacity of 1.4 million tons is required. As a result, the Qualified Persons are satisfied with the quantum of the additional cost set out above and the timeframe for the upgrades. There are no specific recommendations for additional work at East Boulder Mine or the Columbus Metallurgical Complex. The geological models and LoM plans for the operations will be updated and refined as new information becomes available. Most of the costs associated with the generation of new data and updates of the geological models and LoM plans as well as Mineral Resource and Mineral Reserve estimates are accounted for in the capital and operating cost budgets. The Qualified Persons do not anticipate significant additional costs for the undertaking of this work. 306 RELIANCE ON INFORMATION PROVIDED BY REGISTRANT The Qualified Persons have relied on information provided by the Registrant in preparing the findings and conclusions regarding the following aspects of the modifying factors outside of the Qualified Persons’ expertise:  Macroeconomic trends, data and assumptions – Section 19;  Marketing information and plans within the control of the registrant – Section 16;  Legal matters outside the expertise of the qualified person – Sections 3.3 and 3.4;  Environmental matters outside the expertise of the Qualified Person – Section 17; and  Governmental factors outside the expertise of the Qualified Person – Sections 3.2, 3.4, 17 and 20.


307 QUALIFIED PERSON’S CONSENT AND SIGN-OFF Based on the technical support and advice from the in-house Technical Experts/Specialists who have identified no fatal flaws in the data and information pertaining to their technical disciplines and the operations, the Qualified Persons consider it reasonable to rely upon the information on the Sibanye- Stillwater US PGM Operations provided by Sibanye-Stillwater (the registrant). 308 I, Jeff Hughs, am a Qualified Person pursuant to Subpart 1300 of Regulation S-K of the US Securities Act of 1933 (SK-1300) with the responsibility for the preparation and sign-off of the Mineral Resources for the Stillwater and East Boulder Mines. I hereby consent to the following:  the public filing and use by Sibanye-Stillwater of the Technical Report Summary for the Sibanye- Stillwater US PGM Operations effective 31 December 2023;  the use and reference to my name, including my status as an expert or “Qualified Person” (as defined by SK-1300) in connection with the Technical Report Summaries for which I am responsible;  the use of any extracts from, information derived from or summary of the Technical Report Summaries for which I am responsible in the annual report of Sibanye-Stillwater on Form 20-F for the year ended 31 December 2023 (Form 20-F); and  the incorporation by reference of the above items as included in the Form 20-F into any registration statement filed by Sibanye-Stillwater. I certify that I have read the Technical Report Summary of the Sibanye-Stillwater US PGM Operations effective 31 December 2023 being filed by Sibanye-Stillwater that supports the disclosure of the Mineral Resources and Mineral Reserves for the Stillwater and East Boulder Mines. I also certify that the Technical Report Summary of the Sibanye-Stillwater US PGM Operations fairly and accurately represents the information in the sections for which I am responsible. I certify that I have read the Form 20-F and that it fairly and accurately represents the information in the Technical Report Summaries for which I am responsible. Dated this: April 19, 2024 /s/ Jeffrey J. Hughs ________________________ Signature of Qualified Person Jeffrey J. Hughs _______________________ Full Name of Qualified Person AIPG CPG – 11792 ________________________ Professional Registration 309 I, Jennifer Evans, am a Qualified Person pursuant to Subpart 1300 of Regulation S-K of the US Securities Act of 1933 (SK-1300) with the responsibility for the preparation and sign-off of the Mineral Resources for the East Boulder Mine. I hereby consent to the following:  the public filing and use by Sibanye-Stillwater of the Technical Report Summary for the Sibanye- Stillwater US PGM Operations effective 31 December 2023;  the use and reference to my name, including my status as an expert or “Qualified Person” (as defined by SK-1300) in connection with the Technical Report Summaries for which I am responsible;  the use of any extracts from, information derived from or summary of the Technical Report Summaries for which I am responsible in the annual report of Sibanye-Stillwater on Form 20-F for the year ended 31 December 2023 (Form 20-F); and  the incorporation by reference of the above items as included in the Form 20-F into any registration statement filed by Sibanye-Stillwater. I certify that I have read the Technical Report Summary of the Sibanye-Stillwater US PGM Operations effective 31 December 2023 being filed by Sibanye-Stillwater that supports the disclosure of the Mineral Resources and Mineral Reserves for the Stillwater and East Boulder Mines. I also certify that the Technical Report Summary of the Sibanye-Stillwater US PGM Operations fairly and accurately represents the information in the sections for which I am responsible. I certify that I have read the Form 20-F and that it fairly and accurately represents the information in the Technical Report Summaries for which I am responsible. Dated this: April 19, 2024 /s/ Jennifer A. Evans ________________________ Signature of Qualified Person Jennifer A. Evans ________________________ Full Name of Qualified Person AIPG CPG – 11669 ________________________ Professional Registration 310 I, Annette McFarland, am a Qualified Person pursuant to Subpart 1300 of Regulation S-K of the US Securities Act of 1933 (SK-1300) with the responsibility for the preparation and sign-off of the Mineral Reserves for the Stillwater Mine. I hereby consent to the following:  the public filing and use by Sibanye-Stillwater of the Technical Report Summary for the Sibanye- Stillwater US PGM Operations effective 31 December 2023;  the use and reference to my name, including my status as an expert or “Qualified Person” (as defined by SK-1300) in connection with the Technical Report Summaries for which I am responsible;  the use of any extracts from, information derived from or summary of the Technical Report Summaries for which I am responsible in the annual report of Sibanye-Stillwater on Form 20-F for the year ended 31 December 2023 (Form 20-F); and  the incorporation by reference of the above items as included in the Form 20-F into any registration statement filed by Sibanye-Stillwater. I certify that I have read the Technical Report Summary of the Sibanye-Stillwater US PGM Operations effective 31 December 2023 being filed by Sibanye-Stillwater that supports the disclosure of the Mineral Resources and Mineral Reserves for the Stillwater and East Boulder Mines. I also certify that the Technical Report Summary of the Sibanye-Stillwater US PGM Operations fairly and accurately represents the information in the sections for which I am responsible. I certify that I have read the Form 20-F and that it fairly and accurately represents the information in the Technical Report Summaries for which I am responsible. Dated this: April 19, 2024 /s/ Annette McFarland ________________________ Signature of Qualified Person Annette McFarland ________________________ Full Name of Qualified Person Professional Engineer Mining – No. 23215 ________________________ Professional Registration


311 I, Pat Hansen, am a Qualified Person pursuant to Subpart 1300 of Regulation S-K of the US Securities Act of 1933 (SK-1300) with the responsibility for the preparation and sign-off of the Mineral Reserves for the East Boulder Mine. I hereby consent to the following:  the public filing and use by Sibanye-Stillwater of the Technical Report Summary for the Sibanye- Stillwater US PGM Operations effective 31 December 2023;  the use and reference to my name, including my status as an expert or “Qualified Person” (as defined by SK-1300) in connection with the Technical Report Summaries for which I am responsible;  the use of any extracts from, information derived from or summary of the Technical Report Summaries for which I am responsible in the annual report of Sibanye-Stillwater on Form 20-F for the year ended 31 December 2023 (Form 20-F); and  the incorporation by reference of the above items as included in the Form 20-F into any registration statement filed by Sibanye-Stillwater. I certify that I have read the Technical Report Summary of the Sibanye-Stillwater US PGM Operations effective 31 December 2023 being filed by Sibanye-Stillwater that supports the disclosure of the Mineral Resources and Mineral Reserves for the Stillwater and East Boulder Mines. I also certify that the Technical Report Summary of the Sibanye-Stillwater US PGM Operations fairly and accurately represents the information in the sections for which I am responsible. I certify that I have read the Form 20-F and that it fairly and accurately represents the information in the Technical Report Summaries for which I am responsible. Dated this: April 19, 2024 /s/ Patrick Hansen ________________________ Signature of Qualified Person Patrick Hansen ________________________ Full Name of Qualified Person MT PE 75419 ________________________ Professional Registration 312 I, Matt Ladvala, am a Qualified Person pursuant to Subpart 1300 of Regulation S-K of the US Securities Act of 1933 (SK-1300) with the responsibility for the preparation and sign-off of the Mineral Resources for the Stillwater Mine. I hereby consent to the following:  the public filing and use by Sibanye-Stillwater of the Technical Report Summary for the Sibanye- Stillwater US PGM Operations effective 31 December 2023;  the use and reference to my name, including my status as an expert or “Qualified Person” (as defined by SK-1300) in connection with the Technical Report Summaries for which I am responsible;  the use of any extracts from, information derived from or summary of the Technical Report Summaries for which I am responsible in the annual report of Sibanye-Stillwater on Form 20-F for the year ended 31 December 2023 (Form 20-F); and  the incorporation by reference of the above items as included in the Form 20-F into any registration statement filed by Sibanye-Stillwater. I certify that I have read the Technical Report Summary of the Sibanye-Stillwater US PGM Operations effective 31 December 2023 being filed by Sibanye-Stillwater that supports the disclosure of the Mineral Resources and Mineral Reserves for the Stillwater and East Boulder Mines. I also certify that the Technical Report Summary of the Sibanye-Stillwater US PGM Operations fairly and accurately represents the information in the sections for which I am responsible. I certify that I have read the Form 20-F and that it fairly and accurately represents the information in the Technical Report Summaries for which I am responsible. Dated this: April 19, 2024 /s/ Matthew D. Ladvala ________________________ Signature of Qualified Person Matthew D. Ladvala ________________________ Full Name of Qualified Person AIPG CPG - 11941 ________________________ Professional Registration 313 I, Kevin Butak, am a Qualified Person pursuant to Subpart 1300 of Regulation S-K of the US Securities Act of 1933 (SK-1300) with the responsibility for the preparation and sign-off of the Mineral Resources for the Stillwater Mine. I hereby consent to the following:  the public filing and use by Sibanye-Stillwater of the Technical Report Summary for the Sibanye- Stillwater US PGM Operations effective 31 December 2023;  the use and reference to my name, including my status as an expert or “Qualified Person” (as defined by SK-1300) in connection with the Technical Report Summaries for which I am responsible;  the use of any extracts from, information derived from or summary of the Technical Report Summaries for which I am responsible in the annual report of Sibanye-Stillwater on Form 20-F for the year ended 31 December 2023 (Form 20-F); and  the incorporation by reference of the above items as included in the Form 20-F into any registration statement filed by Sibanye-Stillwater. I certify that I have read the Technical Report Summary of the Sibanye-Stillwater US PGM Operations effective 31 December 2023 being filed by Sibanye-Stillwater that supports the disclosure of the Mineral Resources and Mineral Reserves for the Stillwater and East Boulder Mines. I also certify that the Technical Report Summary of the Sibanye-Stillwater US PGM Operations fairly and accurately represents the information in the sections for which I am responsible. I certify that I have read the Form 20-F and that it fairly and accurately represents the information in the Technical Report Summaries for which I am responsible. Dated this: April 19, 2024 /s/ Kevin C. Butak ________________________ Signature of Qualified Person Kevin C. Butak ________________________ Full Name of Qualified Person AIPG CPG - 12012 _______________________ Professional Registration 314 REFERENCES Blakely, R.J., and Zientek, M.L., 1985. Magnetic anomalies over a mafic intrusion: The Stillwater Complex. The Stillwater Complex, Montana Bureau of Mines and Geology, Special Publication 92, 2002 reprint. Czamanske, G.K., and Zientek, M.L. eds. Boudreau, A., 1999. Fluid Fluxing of Cumulates: the J-M Reef and Associated Rocks of the Stillwater Complex, Montana, Journal of Petrology, Volume 40, pp 755-772. DEQ and USFS, 1985. Montana Department of Environmental Quality and U.S Forest Service. Final Environmental Impact Statement, Stillwater Project, December 1985. DEQ and USFS, 2012. Final Environmental Impact Statement, Stillwater Mining Company's Water Management Plans and Boe Ranch LAD, May 2012. DEQ and USFS, 2012a. Record of Decision for Stillwater Mining Company's Revised Water Management Plans and Boe Ranch LAD, Stillwater and Sweet Grass Counties, Montana (July 2012). DEQ and USFS, 2020. Draft Environmental Assessment East Boulder Mine Stage 6 Tailings Storage Facility Expansion Project, May 2020. DEQ, 2001. Montana Department of Environmental Quality Bonding Procedure Manual. 2001. Jenkins, M.C., Mungall, J.E., Zientek, M.L., Butak, K., Corson, M. Holick, P., McKinley, R., and Lowers, H., 2022. The Geochemical and Textural Transition between the Reef Package and its Hanging Wall, Stillwater Complex, Montana, USA. Journal of Petrology, 2022, 63, pp1-30. Kleinkopf, D.M., 1985. Regional gravity and magnetic anomalies of the Stillwater Complex area. The Stillwater Complex, Montana Bureau of Mines and Geology, Special Publication 92, 2002 reprint. Czamanske, G.K., and Zientek, M.L. eds. McCallum, I.S., 2002. The Stillwater Complex: A review of the geology. In: Boudreau, A.E., (ed.). Stillwater Complex, Geology and Guide. Billings, 21-25 July 2002, 9th International Platinum Symposium, A1-25. Page, N.J., and Zientek, M.L., 1985. Geologic and structural setting of the Stillwater Complex. The Stillwater Complex, Montana Bureau of Mines and Geology, Special Publication 92, 2002 reprint. Czamanske, G.K., and Zientek, M.L. eds. Stillwater Mining Company, Northern Plains Resource Council, Cottonwood Resource Council, Stillwater Protective Association, 2014. Good Neighbor Agreement. Amended December 8, 2014. Zientek, M.L., Czamanske, G.K., and Irvine, N.T., 1985. Stratigraphy and nomenclature for the Stillwater Complex. The Stillwater Complex, Montana Bureau of Mines and Geology, Special Publication 92, 2002 reprint. Czamanske, G.K., and Zientek, M.L. eds.