Phase 1 Results
Based on the Phase 1 test results available at the time and prior historical column test work, the PEA used an average copper recovery of 72.8% by employing conventional bio-heap leaching technology (see results published
The potential impact of the 3.2% increase in average recovery and 8.3% reduction in net acid consumption can be illustrated by selectively adjusting the PEA Base Case financial model, which results in a life of mine copper cathode production increase of 172,000 tonnes and an after-tax NPV(8%) increase of approximately
Deposit Mineralogy
Located in
Metallurgical Testing Phases
Preliminary results from the Phase 1 program along with historical metallurgical testing at Los Azules were used to support the 2023 Preliminary Economic Assessment (PEA), which proposed an environmentally friendly heap leach alternative to a conventional copper concentrator. The testing program is now advancing with two additional phases (2 & 3) currently underway to support the Feasibility Study (FS). Drilling activities related to the current study work started in 2021 and are continuing into 2024. The leach testing protocols are based on conventional bio-leaching methods used extensively in commercial applications for supergene copper mineralization. The current phases, 2 & 3, are being conducted at SGS Chile and
The Phase 1 program was initiated using drill core from drilling programs completed prior to 2021, but not older than 2015, for a total of 21 column tests. Started in 2022, Phase 1 has now been completed and final results received. Preliminary results of this work and prior historical leach testing information were used for the PEA metallurgical assumptions.
The Phase 2 program utilizes drill core from the 2022-2023 drilling campaign and focuses on deposit-wide variability testing, leaching protocol optimization and scalability. A total of 34 column tests are in progress, with results expected in Q2 2024.
The Phase 3 program is also started, utilizing additional drill core material from the ongoing 2023-2024 drilling program. Phase 3 testing is focusing on the material of the initial 5-year mine plan, as delineated in the PEA. A total of 33 additional column tests are planned as part of this final confirmatory testing program, with results anticipated in Q4 2024.
The combined metallurgical programs comprise a total of 88 column tests to be used for the FS metallurgical design basis and geo-metallurgical model.
Copper assaying is conducted using a sequential method to determine the relative amounts of acid soluble (CuAS) and cyanide soluble (CuCN) copper mineralization (oxides and secondary sulfides). When combined, these two partial assay methods are generally considered readily soluble copper (CuSOL), extractable with conventional heap leaching technologies. Copper assayed that does not report to these two partial assay methods is classified as residual copper (CuRES) and is considered copper that requires additional time or is potentially not recoverable with conventional heap leaching technologies.
The finalized results from the Phase 1 metallurgy program for tests completed at minus ½" and ¾" crush sizes confirmed that soluble copper (CuSOL) component recovery is 100% for all leachable resources. The information in Figure 1 below shows the minus ¾" (19 mm) test results. The PEA envisions a minus ¾" crush size for the heap leaching feed in the commercial application.
Figure 1 – Soluble Copper Recovery Kinetics
The recovery results for the residual copper (CuRES) component shown in Figure 2 indicated an average recovery of 25%, an increase of 10% from the 15% preliminary recovery assumption used in the PEA. The additional residual copper recovery when applied to the entire resource increases the overall average recovery from 72.8% to 76.0%.
Figure 2 – Residual Copper Recovery Kinetics
Figure 3 below illustrates the increase in potential copper production throughout the mine life, attributable to the improved recovery, in comparison with the PEA assumptions. The initial two production years do not show additional recovered copper, as the design capacity of the electrowinning plant considered in the PEA is fully utilized.
Figure 3 – Copper Cathode Production (PEA & Revised Model)
The sulfuric acid consumption has also been updated with the Phase 1 final results. The averaged net sulfuric acid consumption reported in the PEA was 18 kilograms per ton of ore processed. The finalized Phase 1 testing now indicates a reduction of 8.3% to 16.5 kilograms per ton. The primary reason for the reduction of acid consumption is minimizing excess acid in the leaching solutions and operating the columns at a pH closer to 2.0 pH than the historic column work at 1.2 pH, which minimizes acid consumption by excess unmineralized gangue material dissolution. This lowered acid requirement may also improve the project economics, both NPV and IRR, by reducing the operating costs for copper produced and increasing revenue from the same tonnes mined.
Bioleaching Summary
Copper bioleaching has been a commercially applied technology at altitudes similar to the Los Azules site and as much as 1,000 meters higher for several decades, in multiple locations around the world. Testing is conducted in conventional leach test columns by inoculation of the columns with naturally occurring bacterial ferrooxidans and thiooxidans prior to introduction of the leach solution. Bacterial cultures for the inoculum were sourced from the testing laboratories and adapted to the Los Azules leach material. Ferrooxidans convert the ferrous iron in solution to ferric iron, while thiooxidans convert the sulfur produced in the copper sulfide leaching activity to sulfuric acid/sulfate. Ferric iron is the key chemical component necessary for leaching of copper sulfide material. Bioactivity in the tests is monitored by measurement of the ferrous/ferric ratios and electrochemical oxidation potential in the leaching solutions.
ABOUT MCEWEN COPPER
McEwen Copper is a well-funded, private company which owns 100% of the large, advanced-stage Los Azules copper project, located in the San Juan province,
Los Azules is being designed to be distinctly different from conventional copper mines, consuming significantly less water, emitting much lower carbon levels and progressing to be carbon neutral by 2038, being powered by 100% renewable energy once in operation. The project’s recently updated Preliminary Economic Assessment (PEA) projects a long life of mine, low production costs per pound, a short payback period, high annual copper production, and an after-tax IRR of 21.1%.
ABOUT
CAUTION CONCERNING FORWARD-LOOKING STATEMENTS
This news release contains certain forward-looking statements and information, including "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995. The forward-looking statements and information expressed, as at the date of this news release,
The NYSE and TSX have not reviewed and do not accept responsibility for the adequacy or accuracy of the contents of this news release, which has been prepared by the management of
Want News Fast?
Subscribe to our email list by clicking here:
https://www.mcewenmining.com/contact-us/#section=followUs
and receive news as it happens!!
WEB SITE | SOCIAL MEDIA | ||
www.mcewenmining.com | McEwen Mining | Facebook: | facebook.com/mcewenmining |
LinkedIn: | linkedin.com/company/mcewen-mining-inc- | ||
CONTACT INFORMATION | Twitter: | twitter.com/mcewenmining | |
Instagram: | instagram.com/mcewenmining | ||
Suite 2800, PO Box 24 | |||
McEwen Copper | Facebook: | facebook.com/ mcewencopper | |
M5H 1J9 | LinkedIn: | linkedin.com/company/mcewencopper | |
Twitter: | twitter.com/mcewencopper | ||
Relationship with Investors: | Instagram: | instagram.com/mcewencopper | |
(866)-441-0690 - Toll free line | |||
(647)-258-0395 | Facebook: | facebook.com/mcewenrob | |
LinkedIn: | linkedin.com/in/robert-mcewen-646ab24 | ||
info@mcewenmining.com | Twitter: | twitter.com/robmcewenmux | |
Figures accompanying this announcement are available at:
https://www.globenewswire.com/NewsRoom/AttachmentNg/a00f17e3-f10b-4352-a03b-0d5f24cad26d
https://www.globenewswire.com/NewsRoom/AttachmentNg/dc6f3341-d17c-4a66-b6ad-060ef3149d8e
https://www.globenewswire.com/NewsRoom/AttachmentNg/1f5e3e19-5a50-4e5e-941e-758057522548
Figure 1 – Soluble Copper Recovery Kinetics
Figure 1 – Soluble Copper Recovery Kinetics
Figure 2 – Residual Copper Recovery Kinetics
Figure 2 – Residual Copper Recovery Kinetics
Figure 3 – Copper Cathode Production (PEA & Revised Model)
Figure 3 – Copper Cathode Production (PEA & Revised Model)
2024 GlobeNewswire, Inc., source