TORONTO, April 18, 2023 (GLOBE NEWSWIRE) -- Doré Copper Mining Corp. (the "Company" or "Doré Copper") (TSXV: DCMC; OTCQX: DRCMF; FRA: DCM) is pleased to announce positive results from ore sorting test work for its flagship Corner Bay high-grade copper-gold project located approximately 55 kilometers by road from the Corporation's Copper Rand mill, near Chibougamau, Québec.

Steinert was commissioned to complete ore sorting tests at their facility in Kentucky, United States, using a XRT sensor (X-ray transmission) and a laser sensor on a spatially diverse sample from the Corner Bay deposit.

The results support the first ore sorting test work that was completed for the preliminary economic assessment ("PEA") and further confirm the effectiveness of utilizing ore sorting technology to improve the processed grade and reduce the mill feed tonnage.

Highlights of Ore Sorting Test

• Copper grade increase of 77%, from 2.20% to 3.93%
• Recovery of 93.6% Cu
• Reject material contains 48% of the initial mass with a copper grade of 0.30%
• Gold, silver and molybdenum grade also upgraded with excellent recoveries and low concentration in reject
• Cost and environmental benefits include:
  • Lower transportation costs and greenhouse gas emissions (GHGs) due to a reduction of transported material from the mine to the mill
  • Lower energy consumption at the mill due to higher feed grade and hardness decrease of the feed material
  • Less tailings produced
  • Additional capacity of the mill to treat additional materials
  • Waste material at the mine site (reject material) to be used as backfill

Commenting on the results of our second ore sorting tests, Ernest Mast, President & CEO, stated, "This test work further validates the favorable mineralogy of the Corner Bay deposit for ore sorting technology and confirms the prior ore sorting results obtained from the Corner Bay stockpile, which were included in the PEA. Preliminary ore sorting test work at Devlin in 2022, our secondary hub-and-spoke asset, had also indicated positive results. Ore sorting of the Corner Bay and Devlin will remain part of any future development scenarios due to its economic and sustainability benefits."

Ore Sorting Tests

As a first step, the Steinert XRT was calibrated with high, medium and low grade and waste samples representative of the selected drill core samples of the Corner Bay deposit (Figure 1). A continuous production run was done on the 202 kg sample. The testing was done with three passes with the explicit aim of generating grade vs recovery vs mass pull curves, with each pass related to an adjustment in the sensitivity. Results are shown in the table below.

The sum of the two pre-concentrates (Test 2 in table below) represented 52.5% of the feed mass at a grade of 3.93% Cu (an increase of 77%) and resulted in a cumulative copper recovery of 93.6%. The final reject portion represented 47.5% of the feed mass at a grade of 0.30% Cu, representing 6.4% of the copper fed in the sorter. In addition, all other metals to be recovered (gold, silver and molybdenum) showed an upgrade in grade:

• Gold grade: from 0.17 g/t to 0.29 g/t
• Silver grade: from 7.91 g/t to 13.82 g/t
• Molybdenum grade: from 0.037% to 0.064%
  

Lastly, the arsenic grade of the two pre-concentrates was found to be 12ppm which leads to a final concentrate with very low levels of arsenic.

Minimal fines were generated in the test work and were not considered for calculations. In practice, the fine material from the mining and crushing would join the pre-concentrate in the ore sorting circuit and would result in a higher recovery than indicated in the test work. In addition, as the sorter can be calibrated to control the final reject grade, a higher copper feed grade would result in higher recoveries.

Corner Bay Composite Sample

A spatially diverse composite sample was prepared by Doré Copper by selecting 34 diamond drill holes which intersected mineralized zones within the Corner Bay Mineral Resource estimate ("MRE") (Figure 1; one mineralized sample was outside the current MRE). The core material selected represented different rock types: semi and massive sulphides, quartz veins, diorite dyke, and fresh and altered anorthosite. The drill core was sampled by cutting a quarter split NQ core. The longer pieces of quarter split core were further manually broken down into 1 to 3 inches length to simulate a crushed product. The composite sample weighted 202 kg and graded 2.20% Cu (Test 4 in table above) and included an 18% external mining dilution from the hanging wall and foot wall of the mineralized interval.

The PEA did not include the silver and molybdenum content (currently excluded from the MRE). The composite sample indicated silver and molybdenum grades that would be expected in the deposit (Test 4 in table above).

Substantial Benefits of Ore Sorting

As already indicated in the Company's PEA (May 10, 2022), ore sorting technology offers substantial benefits versus conventional processing. It will reduce operating costs for milling, flotation and tailings management due to a significant rejection of low-grade material. Sorting is expected to decrease the hardness of the ore sent to the mill (lower Bond Work Index of the sorter pre-concentrate product compared to the feed), and so, non-negligeable energy savings could be foreseen. The commensurate increase in the head grade of the ore that will report to the flotation circuit has the potential to result in improved metallurgical recoveries in the flotation circuit and higher concentrate grades.

Further metallurgical and environmental testing, including comminution, flotation and leachability testing, will be carried out to progress the feasibility study and ongoing permitting.

Figure 1. Sample Location for Composite Sample Used in Ore Sorting Test

Qualified Person

Ernest Mast, P.Eng., President and CEO of the Corporation, and a "Qualified Person" within the meaning of National Instrument 43-101 – Standards of Disclosure for Mineral Projects, has reviewed and approved the scientific and technical information contained in this news release.

About Steinert

Steinert is a global provider of intelligent sorting and separation solutions for the recycling and mining industries. Steinert, has over 125 years of experience, excels at providing customers technologically advanced sorting solutions via its extensive process and industry knowledge.

Steinert has been a pioneer in the market, consistently pursuing and achieving its goal of supporting customers by being a global technology leader. Founded in 1889 in Cologne, Germany, Steinert is the only manufacturer of magnetic separators that has further advanced its classic field of activity and established sensor-based sorting as a new technology in its product development.

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About Doré Copper Mining Corp.

Doré Copper Mining Corp. aims to be the next copper producer in Québec with an initial production target of +50 Mlbs of copper equivalent annually by implementing a hub-and-spoke operation model with multiple high-grade copper-gold assets feeding its centralized Copper Rand mill¹. The Company has delivered its PEA in May 2022 and is proceeding with a feasibility study.

The Company has consolidated a large land package in the prolific Lac Doré/Chibougamau and Joe Mann mining camps that has historically produced 1.6 billion pounds of copper and 4.4 million ounces of gold² The land package includes 13 former producing mines, deposits and resource target areas within a 60-kilometre radius of the Company's Copper Rand Mill.

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1. Technical report titled "Preliminary Economic Assessment for the Chibougamau Hub-and-Spoke Complex, Québec, Canada" dated June 15, 2022, in accordance with National Instrument 43-101 – Standards of Disclosure for Mineral Projects. The Technical Report was prepared by BBA Inc. with several consulting firms contributing to sections of the study, including SLR Consulting (Canada) Ltd., SRK Consulting (Canada) Inc. and WSP Inc.
2. Sources for historic production figures: Economic Geology, v. 107, pp. 963–989 - Structural and Stratigraphic Controls on Magmatic, Volcanogenic, and Shear Zone-Hosted Mineralization in the Chapais-Chibougamau Mining Camp, Northeastern Abitibi, Canada by François Leclerc et al. (Lac Dore/Chibougamau mining camp) and NI 43-101 Technical Report on the Joe Mann Property dated January 11, 2016 by Geologica Groupe-Conseil Inc. for Jessie Ressources Inc. (Joe Mann mine). Doré Ramp November 1992 Summary, internal Westminer Report.

Cautionary Note Regarding Forward-Looking Statements
This news release includes certain "forward-looking statements" under applicable Canadian securities legislation. Forward-looking statements include predictions, projections and forecasts and are often, but not always, identified by the use of words such as "seek", "anticipate", "believe", "plan", "estimate", "forecast", "expect", "potential", "project", "target", "schedule", "budget" and "intend" and statements that an event or result "may", "will", "should", "could" or "might" occur or be achieved and other similar expressions and includes the negatives thereof. All statements other than statements of historical fact included in this news release, including, without limitation, statements with respect to the timing and ability of the Company to receive necessary regulatory approvals, the Company's ability to meet its production target, the commencement, timing and completion of a feasibility study, and the plans, operations and prospects of the Company and its properties are forward-looking statements. Forward-looking statements are necessarily based upon a number of estimates and assumptions that, while considered reasonable, are subject to known and unknown risks, uncertainties and other factors which may cause actual results and future events to differ materially from those expressed or implied by such forward-looking statements. Such factors include, but are not limited to, actual exploration results, changes in project parameters as plans continue to be refined, future metal prices, availability of capital and financing on acceptable terms, general economic, market or business conditions, uninsured risks, regulatory changes, delays or inability to receive required regulatory approvals, health emergencies, pandemics and other exploration or other risks detailed herein and from time to time in the filings made by the Company with securities regulators. Although the Company has attempted to identify important factors that could cause actual actions, events or results to differ from those described in forward-looking statements, there may be other factors that cause such actions, events or results to differ materially from those anticipated. There can be no assurance that such statements will prove to be accurate, as actual results and future events could differ materially from those anticipated in such statements. Accordingly, readers should not place undue reliance on forward-looking statements. The Company disclaims any intention or obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise, except as required by law.

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