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