On November 1 2025, Rio Tinto produced the first copper cathode from its Nuton bioleaching technology at the Johnson Camp mine in Arizona, marking the first commercial‑scale output of a process that eliminates traditional concentration, smelting and refining steps.
The Nuton system, a modular package that couples biology, chemistry, engineering and digital monitoring, achieved an 85 % recovery rate and a mine‑to‑metal carbon footprint of 0.82 kg CO₂‑eq per kilogram of copper—currently the lowest in the United States. Water usage is projected at 71 litres per kilogram of copper, and the four‑year demonstration period is targeting 30,000 tonnes of refined copper.
This milestone aligns with Rio Tinto’s strategy to diversify beyond iron ore and to hit its 1 million‑tonne‑per‑year copper target by 2030. The company’s copper segment now accounts for roughly 15 % of total revenue, and the Nuton technology could reduce operating costs by eliminating smelting and refining, potentially improving margins and enabling a premium price for low‑carbon copper. Rio Tinto’s recent $6.7 billion acquisition of Arcadium Lithium further underscores its commitment to future‑facing metals.
Katie Jackson, Rio Tinto’s Copper Chief Executive, said the achievement demonstrates that “cleaner, faster, and more efficient copper production is possible at an industrial scale.” Stephen Twyerould, President of Gunnison Copper, added that the technology “strengthens the U.S. supply chain for low‑carbon copper.” These comments highlight the strategic importance of the technology for both Rio Tinto’s growth and the domestic market’s transition to greener metals.
The broader mining industry is increasingly focused on sustainability, and low‑carbon production methods like Nuton are becoming critical for maintaining social license to operate and meeting investor ESG expectations. By proving the technology at scale, Rio Tinto positions itself as a leader in green copper, potentially attracting new customers and setting a benchmark for the sector.
Looking ahead, Rio Tinto plans to scale Nuton beyond the Johnson Camp demonstration, with the goal of integrating the process into its global copper portfolio. Successful scaling would accelerate the company’s 2030 copper target and reinforce its competitive edge in a market where demand for clean‑energy materials is rising sharply.
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