title: “Hudbay, Mitsubishi Approve $2.07B Arizona Copper Mine Construction” url: “https://www.enr.com/articles/64075-hudbay-mitsubishi-approve-207b-arizona-copper-mine-construction” author: “Bryan Gottlieb”
Toronto-based copper miner Hudbay Minerals and Mitsubishi Corp. approved construction Oct. 21 of a $2.07-billion open-pit copper mine and processing complex in southern Arizona, launching the initial phase of their Copper World joint venture.
The project, about 31 miles southeast of Tucson, is owned 70% by Hudbay and 30% by Mitsubishi and is expected to begin production in the second half of 2029. The final investment decision follows completion of a definitive feasibility study for Copper World.
Initial construction calls for an open-pit mine, a concentrator capable of processing 60,000 tons of ore per day and related infrastructure. Hudbay says the amount reflects project spending during the 36 months before commercial production, including around $200 million in scope changes since its 2023 prefeasibility study.
The base project is planned as a conventional open-pit, truck-and-shovel operation across four primary pit areas—East, Broadtop, West and Peach-Elgin—with waste-rock facilities, grade-segregated ore stockpiles, a tailings storage facility and supporting infrastructure. Hudbay expects construction to employ more than 1,000 workers, with about 500 permanent operating positions once the mine is running.
Hudbay says it has obtained all major permits needed to construct and initially operate the base project. The 15-year base mine plan remains within Copper World’s private land boundary and requires only state and local approvals.
More Construction Planned After Startup
Copper World has revised its development plans several times. Hudbay recast the former Rosemont Copper project in a 2022 preliminary economic assessment as a phased development, with an initial operation on private land followed by potential expansion onto federal land.
Copper World’s site plan shows the East, Broadtop, West and Peach-Elgin pit areas along with the mill, waste-rock and tailings facilities planned for the Arizona mine.
A 2023 prefeasibility study envisioned a 60,000-ton-per-day concentrator and a year-five concentrate-leach and solvent extraction-electrowinning plant to produce copper cathode. The development plan released with the definitive feasibility study retains the initial 60,000-ton-per-day concentrator but incorporates a larger mill expansion, an in-pit crushing and conveying system and a filtered-tailings strategy. The concentrate-leach facility remains a possible future addition.
Under the new plan, Hudbay would build a $25-million molybdenum processing plant in the first year of operation and a $242-million in-pit crushing and conveying system in year three. The system would crush ore in the East pit and move it by conveyor to stockpiles and the processing plant. Designed to handle up to 100,000 tons per day, it would reduce haul-truck requirements, emissions and operating costs.
Another $443 million would be invested in year four to expand the concentrator from 60,000- to 90,000 tons per day beginning in year five. The expansion would lift average annual copper production from about 92,600 tons during the first five years to 132,300 tons during years six through 10. Hudbay expects to fund the expansion with operating cash flow and an additional $70-million payment from Wheaton Precious Metals.
The plan also calls for converting about one-third of the project’s tailings to filtered tailings beginning in year five, allowing the concentrator expansion without requiring an additional water supply.
Pima County Administrator Jan Lesher noted “increased production, the apparent use of dry stack or filtered tailings, and changes in mine facility configurations” in an Oct. 21 memo to county supervisors. County staff will review the feasibility study and report its findings to the board, she said. Lesher said staff also plans to meet with state water regulators concerning Hudbay’s water-pumping permit, which expires in January 2028.
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Ariz. Dept. of Environmental Quality — Aquifer Protection Program Permit
Arizona environmental regulators issued Copper World’s aquifer protection permit in August 2024 after determining statutory and regulatory requirements for issuing the permit had been met. During the permit review, the Arizona Dept. of Environmental Quality said design changes during mine development “are common and must be addressed through the established permitting process.” The agency said changes to regulated discharging facilities, including design modifications, require the permittee to submit an amendment application.
Local Opposition Persists
The Pima County Board of Supervisors voted 3-1 in January to direct the county administrator to communicate to regulators, Hudbay stakeholders and other parties its continuing opposition. Tucson’s City Council unanimously adopted a resolution May 5 opposing Copper World and open-pit mining in the Santa Rita Mountains.
“This is a county that embraces mining,” county Board of Supervisors Vice Chair Matt Heinz told KJZZ in a May interview. “We work with ASARCO. We partner with them, so this isn’t like a no-mining—not in my backyard—never ever. It’s just, why here?” County officials have cited an aquifer already experiencing declining water levels and subsidence, along with potential air- and water-quality impacts.
“The Santa Rita mountains, which we call Ce:wi Duag, hold our history, our sacred places and the living connections between our people and the natural world,” Tohono O’odham Nation Chairman Verlon Jose said in July. “We have a collective responsibility to protect the Santa Rita Mountains for future generations.”
Financing the Build
The Santa Rita Mountains south of Tucson are the proposed site of the Copper World mine, which has drawn opposition from local governments, environmental groups and the Tohono O’odham Nation.
Photo by Russ McSpadden/Center for Biological Diversity
Mitsubishi’s initial $600-million joint-venture investment and a $230-million precious-metals stream deposit from Wheaton are expected to provide the first major sources of construction capital. Hudbay also anticipates $127 million in equipment financing and approximately $650 million in project-level debt.
Hudbay’s funding plan “only requires Hudbay to fund one-quarter of the project capital cost and defers Hudbay’s first capital contribution to 2028,” company President and Chief Financial Officer Eugene Lei said in a statement.
Mitsubishi says its additional equity commitment could reach $423 million, although Hudbay estimates it would be about $218 million if it secures the anticipated project-level debt.
The company is also studying a longer-term expansion onto adjacent federal lands beginning around Copper World’s 10th operating year. That scenario would require federal approvals and could extend the mine life from 15 to 37 years.
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Man this sucks. We don’t need a fourth open pit copper mine around town.
