Pinto Valley is Capstone’s long-life, multi-generational open pit copper mine. The mine provides unrivalled leverage to copper with growing production through quick payback, high impact projects. Concurrently, Capstone is evaluating Pinto Valley’s long-term growth potential beyond its current mine life.

An Exciting Future

>1 billion tonnes of M&I

Currently of Measured and Indicated Resources, not in Reserve

Current mine life to 2039

PV4 Expansion evaluating long-term growth potential of M&I Resource and expansion scenarios

Currently permitted to 79.5 ktpd

PV3 Optimization targeting 57 ktpd by 2021 and 60+ ktpd by 2022, with improved copper recoveries

Pinto Valley is currently the only operating mill located in the historic Globe-Miami mining district of Arizona, one of the oldest and most productive mining districts in the United States. Since its first recorded production in 1975, Pinto Valley has produced more than four billion pounds of copper, including 0.5 billion pounds of copper cathode. Capstone acquired Pinto Valley from BHP Billiton in October 2013 and is currently the second-largest employer in the district contributing over $270 million annually to Arizona’s economy.

Capstone is positioning Pinto Valley to be optimized in time for higher copper prices. The PV3 Optimization focused on innovation and a series of low-capital, quick payback projects to debottleneck operational performance. The project has improved productivity, increased recoveries and increased throughput to 60,000 tpd during peaks. The mine received a new US Forest Service Mine Plan of Operations in November 2021 and is fully permitted to operate until 2039.

A PV4 Study is evaluating the mine’s long-term growth potential of Measured and Indicated Resources (inclusive of Reserves) of over 1.36 billion tonnes at 0.30% copper. The study includes a series of technological innovations including:

  • Jetti Catalytic Leach Technology: It has the potential to increase cut-off grades to the mill and increase tonnage under leach. Scenarios include increased mining rates, higher mill grades and increased leaching. A column leach test is ongoing through the first half of 2022.
  • Coarse Particle Fotation (CPF) Technology: It has the potential to increase copper recoveries by at least 6% to a total of ~90% while providing flexibility to increase mill throughput.
  • Pyrite Agglomeration: To divert acid-generating minerals including chalcopyrite from tailings to the dump leaching operations, where additional Copper can be recovered and some acid necessary for production can be generated. This is a low-capital project (~7M with a quick one-year payback).

Pinto Valley is also evaluating other new technologies such as Autonomous Trucking.

Innovation and Optimization 

Jetti Resources: Pinto Valley has successfully demonstrated positive economics by applying a novel patented catalytic technology from Jetti Resources to existing dump leach. The plan is to increase copper cathode production to 300-350 million pounds from mineralized waste over the next two decades, generating strong cash flow from the mine’s underutilized SX-EW plant, which is currently operating at only 20% capacity. Read the full news release.

Coarse particle flotation: Pilot plant testing of a new coarse particle flotation technology by Eriez Flotation Division, the world leader in innovative flotation technology, commenced in December 2020. Positive pilot plant testing showed that a 6 to 8% increase to overall copper recovery is achievable. Other benefits could be lower grinding costs, lower water and energy consumption and increased tailings stability via coarser tailings. The project is in final stage review, read the January 19, 2021 news release for more details. 

PV3 Optimization – Time-lapse of Ball Mill #3 Change Completed in 2021



Pinto Valley Location

Geology and Mining

Geological setting Porphyry Copper Deposit - primary host rock is the Precambrian-age Lost Gulch Quartz Monzonite, (equivalent to the Oracle Granite or Ruin Granite).
Economic Mineralization Hypogene ore body with chalcopyrite, pyrite, and minor molybdenite as the significant primary sulfide minerals
Mining method Open pit
Primary product mined Copper
By-products mined Molybdenum

Technical Reports

Download item year list

Reserves & Resources

Pinto Valley Minerals Reserves, Remaining at March 31, 2021

Classification Tonnes (millions) % Cu % Mo Contained Cu (Mlb) Contained Mo (Mlb)
Proven 241.6 0.34 0.007 1,833 35.6
Probable 139.4 0.28 0.006 877 17.4
Total P+P 381.0 0.32 0.006 2,710 53.0

NOTE: The Mineral Reserve has an effective date of March 31, 2021 and was prepared by Clay Craig, P.Eng., Manager, Mining and Evaluations at Capstone Mining Corp. The economic assumptions include the following: $3.00/lb Cu and $10.00/lb Mo, 86.0% average Cu recovery, 8.5% average Mo recovery, $1.68/tonne average mining costs, $1.13/tonne G&A costs, $0.88/tonne Ops Support costs, $4.67/ton milling costs, and pit slopes by rock type. The Mineral Reserve is reported at a variable cut-off ranging from 0.17% to 0.21% copper. Tonnage measurements are in metric units. Copper and molybdenum grades are reported as percentages. Contained metal is reported as million pounds. Rounding may result in apparent summation differences between tonnes, grade and contained metal.

Pinto Valley Mineral Resource at 0.14% Copper Cutoff, as of March 31, 2021

Classification Tonnes (millions) % Cu % Mo Contained Cu (Mlb) Contained Mo (Mlb)
Measured (M) 619.9 0.33 0.006 4,442.7 83.4
Indicated (I) 782.5 0.26 0.005 4,493.6 88.0
Total M & I 1,402.3 0.29 0.006 8,934.6 170.0
Inferred 170.6 0.26 0.006 967.6 20.7

NOTE: The Mineral Resource is classified according to CIM (2014) definitions, estimated following CIM (2019) guidelines and has an effective date of March 31, 2021. The Independent Qualified Person for the estimate is Mr. Garth D. Kirkham, P.Geo., FGC., Of Kirckham Geosystems Ltd. The economic assumptions include the following: $3.50/lb Cu, $10.00/lb Mo, 84.6% average Cu recovery, 8.9% average Mo recovery, $1.74/tonne average mining costs, $1.13/tonne G&A costs, $0.88/tonne operational support costs, $4.67/ton milling costs, and pit slopes by rock type. The Mineral Resource is reported inclusive of the Mineral Reserve.  The last date for drilling data and mining activities is March 31, 2021. Rounding may result in apparent summation differences between tonnes, grade and contained metal.