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Sulphur 420 Sep-Oct 2025

18 September 2025

Copper output begins at Rio Tinto-backed project

UNITED STATES

Copper output begins at Rio Tintobacked project

Gunnison has started producing pure copper cathodes at its Johnson Camp Mine (JCM) in southeast Arizona, United States, from a solvent extraction-electrowinning (SX-EW) circuit and using leaching technology from Rio Tinto-owned Nuton. As well as giving Gunnison exclusive rights to deploy the proprietary process on run-of-mine ore, Nuton is a financial partner of the Phoenix-headquartered mine developer which has restarted copper production at past-producing JCM. The company’s next goal is to ramp-up to nameplate plant capacity of 25 million lbs/year (11,300 t/a) of finished copper.

Nuton owns a portfolio of proprietary leaching technologies with the potential to economically unlock copper from what is often viewed as hard-to-leach ores, including primary sulphides. Nuton describes itself as a Rio Tinto venture.

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