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Los Azules

About Los Azules

Located in San Juan, Argentina

Los Azules is an advanced-stage porphyry copper exploration project in the San Juan pro-mining province of Argentina. The project is located approximately 80 km west northwest of the Calingasta town and 6 km east of Argentina's border with Chile, at 3,500 m elevation in the Andes Mountains.

Los Azules is one of the world's largest undeveloped high grade open pit copper projects that contains significant further growth potential. According to the project’s Preliminary Economic Assessment (PEA) completed in 2017, during the first 10 years of the 36 years of operations the project is anticipated to be a world top 25 copper producer, in the lowest cost quartile.

About Diagram About Diagram


On July 6, 2021 McEwen Mining announced the creation of the wholly-owned subsidiary, McEwen Copper Inc., which holds 100% interests in the Los Azules project in Argentina and in the Elder Creek exploration property in Nevada. Both assets are subject to a 1.25% net smelter return (NSR) royalty payable to McEwen Mining.

McEwen Copper started with 17.5 million common shares outstanding held by McEwen Mining. A private placement financing has been initiated, of up to 8 million shares of McEwen Copper at US$10 per share. The first tranche of the placement was closed with Rob McEwen for $40 million, a second tranche was closed for $15 million, and a third tranche was completed in August, 2022 for $26.9 million, and included a $25 million investment by Nuton, a Rio Tinto venture. Following the completion of the $81.9 million oversubscribed offering, ownership in McEwen Copper is now 68% McEwen Mining and 32% new shareholders.

In connection with the Offering, McEwen Copper entered into a collaboration agreement with Nuton to advance our understanding of the potential application of heap leach technology at Los Azules, including the testing of Nuton® Technologies for compatibility with Los Azules copper mineralization. Leaching has many potential economic and environmental benefits over a conventional milling scenario, including lower water and energy consumption, no dam or large tailings storage facility, and typically lower capital and operating costs.

In 2022 we have resolved the critical issue of road access to Los Azules by the development of a lower altitude access road that provides us with the opportunity for year-round work at the site. The diagram below illustrates the important elevation difference between our exploration road (shown in blue) that allows 5 to 6-month access to site and our new access road (shown in orange) that, in combination, will provide 12-month access. Having two roads into Los Azules represents an important development for the project, making it safer, less expensive and faster to advance and complete our fieldwork.

The first season of the 2022 surface drilling at Los Azules took place from January to late May, with 13,500 m (44,300 ft) completed to date. Three primary objectives of the drilling program include:

  • Improving the confidence in the resource by converting Inferred mineral resources to the Indicated category
  • Accelerating project advancement with metallurgical, hydrological and geotechnical drilling and
  • Testing the limits of the depth extension of the higher-grade mineralization.

Results from the first drilling season can be seen in our Los Azules progress reports press releases #2, #3 and #4). These results will be used to update the 2017 PEA, which had estimated Indicated and Inferred mineral resources of 10.2 and 19.3 billion lbs. of copper, respectively. Extensive enterprise optimization work is also underway on potential larger scale, lower cost and lower carbon footprint alternatives.

Future drilling will evaluate the potential to expand the deposit at depth. While the median depth of drill holes within the Los Azules resource database is 175 m (575 ft), it is not uncommon for porphyry copper mineralization to extend well beyond 1,000 m (3,280 ft) of depth. Numerous drill holes at Los Azules have encountered strong copper grades below the 2017 PEA pit bottom, with all three holes drilled to a depth of over one kilometer ending in copper mineralization.

The next drilling season will take place from October 2022 to June 2023. McEwen Copper has built an experienced management team to complete the updated Preliminary Economic Assessment (PEA) for Los Azules in Q1 2023, followed by initial public listing in H1 2023 and a feasibility study in 2024.

For further information on McEwen Copper, the latest company presentation can be accessed here.

Los Azules

962 Million Tonnes
Estimates Silver

Estimates Gold

Estimates Gold


for Los Azules

In 2017 McEwen Mining announced the results of an updated Preliminary Economic Assessment (PEA) for Los Azules. The report is dated October 16, 2017, with effective date September 1, 2017 (PDF 29MB).

Using the price assumptions of $3.00 per pound of copper, $1,300 per ounce of gold, and $17 per ounce of silver, the Los Azules project generates a $2.2 billion After-Tax Net Present Value (NPV) (discounted at 8%) and 20.1% After-Tax Internal Rate of Return (IRR), demonstrating to be a robust, high margin, rapid payback, and long‑life open pit mine operation.

Estimate of Mineral Resources for Los Azules

The Los Azules PEA includes an updated resource estimate, incorporating the results of the 2016-2017 drilling program. The copper resource contains 10.2 billion pounds in the Indicated category and 19.3 billion pounds in the Inferred category, where most of Indicated material is within the mine pit shell and most of the Inferred material is outside of the mine pit shell.

The mineral resource estimate for Los Azules was prepared utilizing three-dimensional block models based on geostatistical applications. The mineral resources are estimated using ordinary kriging with a nominal block size of 20 m x 20 m x 15 m. To ensure the reported resource exhibits reasonable prospects for economic extraction, the mineral resource is limited within a pit shell generated around copper grades in blocks classified in the Indicated and Inferred categories. Generalized technical and economic parameters include a copper price of $2.75/lb, site operating costs of $1.70/t for mining, $5.00/t for processing and $1.00/t for general and administrative, a pit slope of 34° and 90% metallurgical recovery.


$3.00 / lb Copper
$1,300 / oz Gold
$17 / oz Silver

    The project economics for Los Azules contemplates two years of permitting, drilling, and feasibility studies, followed by three years of project implementation phase for production of the first copper concentrates. The economic values presented in the 2017 PEA are after-tax financial outcomes at the point of commencing the project implementation phase. Some highlights for the Base Case ($3.00/lb copper, $1,300/oz gold, $17/oz silver) include:

  • $2.2 billion After-Tax NPV (8% discount rate) and 20.1% After-Tax IRR;
  • 3.6 year payback and 36 years Life of Mine (LOM);
  • 415 million lb average annual copper production for first 10 years.
  • $1.11/lb average cash copper production costs for first 10 years, $1.28/lb average C1 costs over LOM.

Other Pertinent Details of the PEA

The 2017 PEA is a substantial revision of the previous 2013 PEA and contemplates an enhanced implementation strategy resulting in improved economics while reducing execution risk.

The 2017 PEA envisions an owner-operated mine and conventional concentrator (flotation circuit) producing a copper concentrate for export. A phased implementation approach is employed to optimize initial capital expenditure. Phase 1 implementation will have a daily throughput of 80,000 tonnes per day (tpd), and Phase 2 will deliver a 50% increase in the processing rate to 120,000 tpd.


Pre-production period 3 years
LOM concentrator feed of ore tonnage 1.5 Billion tonnes
LOM waste stripping
(1.05 projected stripping ratio)
1.5 Billion tonnes
Concentrator feed copper grade during first 5 years of operation 0.73%
Current classification of initial mill feed 93% Indicated - 7% Inferred


The Los Azules concentrator will produce copper concentrate as a final product. The process design has been modeled on the flowsheet and implementation of the recently constructed and operating Antapaccay (Glencore) copper concentrator located in the high Andes of Peru. Antapaccay shares many key characteristics with Los Azules, such as ore properties and process plant altitudes, making it an obvious choice upon which to model the proposed infrastructure. Some minor design changes, in equipment sizing only, have been incorporated based on operating experience at Antapaccay. The plant has been designed for average daily throughput of 80,000 tpd. The concentrator would be constructed on-site and would employ one comminution circuit consisting of a primary crusher, stockpile feed conveyor, reclaim conveyor, one SAG mill, two pebble crushers and two ball mills. The comminution circuit would be followed by flotation, thickening and filtration circuits, a Tailings Storage Facility and concentrate storage. LOM recovery of copper to concentrate is expected to be 91% at a concentrate grade of 30% Cu.

It is planned to expand the capacity of the plant to 120,000 tpd by Year 5 through the installation of additional comminution and flotation capacity. Gold and silver are recoverable to the copper concentrate. No other metals have been identified that would yield by-product credits, nor that have significant amounts of penalty elements.

Capital and Operating Costs

Capital Cost Estimate ($ Millions)
Mining Equipment $215
Mine Pre-stripping Cost $193
Surface Scope (Concentrator, Power Line, Tailings, etc.) $979
Total Direct Cost $1,387
Total Indirect Cost $508
Contingency $48
Total Initial Capital Cost $2,363

Operating Cost Estimate

Cost Area Million $/LOM $/t Mill Feed $/t Cu $/lb Cu
Mining 5,404 3.63 980 0.44
Process 5,774 3.88 1,047 0.47
Transport 2,587 1.74 469 0.21
G&A 1,620 1.09 294 0.13
Subtotal OPEX 15,385 10.34 2,789 1.26
Treatment/Refinery Charges 2,684 1.80 487 0.22
Au & Ag Credits (2,449) (1.65) (444) (0.20)
Net Costs 15,621 10.50 2,831 1.28

The PEA was prepared by Hatch Ltd., a global multidisciplinary management, engineering and development consultancy known for leadership in mining innovation, under the direction of Donald Brown C. P. Eng with contributions from other industry specialists.

The 2017 PEA is preliminary in nature. The mine plan and economic model include the use of Inferred resources. Inferred resources are conceptual in nature and are considered to be too speculative to be used in an economic analysis except as allowed for by Canadian Securities Administrators' National Instrument 43-101 in PEA studies. There is no guarantee that Inferred resources can be converted to Indicated or Measured resources. Mineral resources that are not mineral reserves do not have demonstrated economic viability. As such, there is no guarantee the project economics described herein will be achieved.

The Los Azules technical information and figures on this page were derived from the news release titled "Copper Shines Brightly for McEwen Mining – Enhanced Economics for Los Azules" released on September 7, 2017. To access the news release click here.

To access the October 2017 PEA report click here and to access the October 2019 memorandum click here.