Rio Tinto has produced the first copper cathode using its proprietary bioleaching technology at Gunnison Coppers’ Johnson Camp mine in Arizona, marking a step forward in producing copper without the need for smelting and refining.
Rio Tinto’s bioleaching technology, Nuton, was developed over three decades of research and development. Nuton relies on naturally occurring microorganisms to extract copper from primary sulphide ores. These microbes are grown at a large scale in Nuton’s proprietary bioreactors. The microbes then accelerate the oxidation of minerals in the crushed ore heap, generating heat and enabling copper to dissolve into a leach solution, which is then processed into 99.99 per cent pure copper cathode.
Rio Tinto Copper CEO Katie Jackson said: “This is a breakthrough achievement for our Nuton technology, which is proving that cleaner, faster, and more efficient copper production is possible at an industrial scale. In an industry where projects typically take about 18 years to move from concept to production, Nuton has now proven its ability to do this in just 18 months.
The deployment involves the design and delivery of a technology package for a heap leach pad targeting production of approximately 30,000 tonnes of refined copper over a four-year demonstration period. Rio Tinto is engaging with several potential customers in the U.S. to support the domestic copper supply chain.
Nuton boosts mine profitability and resource efficiency by making it possible to extract value from low-grade ores that would typically be discarded as waste, thereby increasing yields and revenue at all mine sites.
Furthermore, its environmental impact is significantly lower than conventional copper processing, using up to 80 per cent less water and generating up to 60 per cent lower carbon emissions compared to the traditional concentrator method.
Gunnison Copper CEO and President Stephen Twyerould said: “The first production of Nuton copper at Johnson Camp is the culmination of exceptional teamwork between Gunnison Copper and Rio Tinto’s Nuton team. Achieving this level of performance in such a short time frame shows what is possible when innovation, operational excellence, and a shared vision come together.”
“Achieving this level of performance in such a short time frame shows what is possible when innovation, operational excellence, and a shared vision come together.”
The next phase for Nuton will focus on validating long-term technical performance.
This includes multi-year testing, independent third-party verification, and internal review by Rio Tinto to ensure consistent recovery rates and environmental performance.
