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Los Azules

About Los Azules

Located in San Juan, Argentina

Los Azules is a 100% owned advanced-stage porphyry copper exploration project located in the cordilleran region of San Juan Province, Argentina, near the border with Chile. 

During the first 10 years of operations Los Azules was anticipated to be the world's 25th largest copper producer and a lowest cost quartile producer. Los Azules is one of the world's largest undeveloped high‑grade open pit copper projects, which contains significant further growth potential.

About Diagram About Diagram

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 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 pay-back, and long‑life open pit mine operation.

Estimate of Mineral Resources for Los Azules

The PEA also 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 16, 2017 PEA report click here.

For further updates and information on the Los Azules project, the October 2019 memorandum can be accessed here.

On July 6, 2021 McEwen Mining announced a non-brokered private placement financing of up to 8,000,000 common shares of its wholly-owned subsidiary McEwen Copper Inc. at a subscription price of US$10.00 per common share, for gross proceeds of up to US$80 million. McEwen Copper currently has 17,500,000 common shares outstanding.

Pursuant to this transaction, McEwen Copper will hold a 100% interest in the Los Azules copper project in San Juan, Argentina, and a 100% interest in the Elder Creek exploration property in Nevada, subject to a 1.25% net smelter return (NSR) royalty on both assets payable to McEwen Mining.

McEwen Copper intends to pursue an initial public listing within 12 months from the closing of this Offering. Proceeds from the Offering will be used exclusively by McEwen Copper to advance the Los Azules project to a pre-feasibility study, construction of a new year-round access road to the project, exploration drilling at Los Azules and Elder Creek, environmental permitting and community relations, and general corporate purposes.

For further information on McEwen Copper, the July 2021 presentation can be accessed here.