A proposed US$500 million redevelopment of the old Cactus (Sacaton) copper mine in Arizona will aim to use cheap “green energy” in the form of the state’s nuclear power, and conventional surface and underground mining methods, to try to turn low-grade ore into payable metal at all-in-sustaining costs of about US$2.30 per pound.
Arizona Sonoran Copper Company’s pre-feasibility study outlines a “lower risk, top-10 potential copper operation in the domestic USA”, producing copper cathodes via heap leach and a solvent extraction/electrowinning (SXEW) plant.
Cactus is about 10km north-west of Casa Grande and not far from Phoenix and the Palo Verde nuclear power plant. An existing 69kv transmission line will help get 7c/kWhr power to the site, according to Arizona Sonoran.
The company proposes to use conventional openpit mining methods for extraction of oxide and secondary sulphide material from the Cactus West pit, and sub-level caving to take out 0.93-0.95% porphyry copper at Parks/Salyer and Cactus East. It also plans to reprocess material from old stockpiles.
The Cactus PFS uses proven and probable reserves totalling 276.3 million tons grading 0.48% soluble copper, or 3 billion pounds of the red metal.
Arizona Sonoran wants to produce about 110Mlb copper a year over 21 years.
“With global copper mine disruptions occurring and a structural deficit currently underway, our timing to develop the asset has a high likelihood to coincide with much higher copper incentive prices,” Arizona Sonoran CEO George Ogilvie said.
“As compared to the original PEA, the PFS demonstrates a significant increase of free cash flow at a conservative long-term copper price assumption of $3.90 per pound.”