Pinto Valley

Pinto Valley is an open-pit mine located at the west end of the historic Globe-Miami mining district of central Arizona, one of the oldest and most productive districts in the US, approximately 80 miles east of Phoenix via Highway 60. Several mines and numerous prospects have been developed in the area. Larger mines in the district are porphyry copper deposits associated with Paleocene granodiorite to Granite Porphyry stocks.

Operation

Pinto Valley has been in operation since 1972 and has produced more than four billion pounds of copper since then. Capstone acquired it from BHP in October 2013. The operation consists of an open-pit mine, a 60,000 tonnes per day (“tpd”) concentrator plant and a 25,000 tpd SX-EW plant. Pinto Valley is currently the only operating mill and the second-largest employer in the Globe-Miami district, supporting ~2,250 direct and secondary jobs each year.

The mine uses conventional open-pit hard rock mining methods (drilling, blasting, loading and hauling) to move copper-bearing sulphide ore to the primary crusher. The processing plant is a conventional porphyry copper concentrator that produces a primary copper sulphide concentrate and a by-product molybdenum concentrate. The plant flowsheet is typical of its era with primary through tertiary crushing, ball milling and conventional flotation. The mill has undergone several optimizations during its life. The most recent upgrade, the $31 million PV3 Optimization, was completed in 2021 and focused on innovation and a series of low-capital, quick payback projects to debottleneck operational performance. This included investments in the fine crushing plant and two new ball mill shells, as well as upgrades to the tailings thickeners and tailings pumping stations. The project improved productivity and increased recoveries and mill throughput to approximately 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 for the duration of the current life of mine plan, which extends to 2039.

Growth – District Growth Study

Pinto Valley is currently progressing a district growth study evaluating the inclusion of a portion of the one billion tonnes of Mineral Resources into the mine plan. This study could result in a mine life extension through 2050. Pinto Valley is also evaluating near-mine district consolidation opportunities in one of the most prolific mining jurisdictions in the United States.

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

Geology and exploration

Pinto Valley is a copper porphyry deposit. The primary host rock is the Precambrian-age Lost Gulch Quartz Monzonite (equivalent to the Oracle Granite or Ruin Granite). The deposit’s economic mineralization is a hypogene ore body with chalcopyrite, pyrite, and minor molybdenite as the only significant primary sulfide minerals.

Copper Cities (BHP Copper Inc.) – The Globe-Miami mining district is host to several deposits and past-producing mining operations. In 2022 Capstone completed a two-phase exploration program under an access agreement to conduct drill and metallurgical test work at BHP Copper Inc’s Copper Cities project, located approximately 10 km east of the Pinto Valley Mine. Drilling with two surface rigs twinning historical drill holes was completed in 2022, with metallurgical testing continuing in 2023.

2024 Guidance

All figures in USD