Rio Tinto Nuton bioleaching at Johnson Camp: brownfield copper upside for planners
Reviewed by Tom Sullivan
First reported on International Mining – News
30 Second Briefing
Rio Tinto has produced its first copper cathode from the Johnson Camp mine in Arizona using its proprietary Nuton® bioleaching technology after more than 30 years of R&D. The Nuton process targets low-grade and complex sulphide ores that are typically uneconomic with conventional heap leach or concentrator routes, aiming to recover additional copper from existing waste and tailings. For mine planners and metallurgists, the trial signals potential brownfield uplift in copper recovery without major new concentrator builds, subject to scale-up performance and permitting.
Technical Brief
- Nuton® applies bioleaching microbes to sulphide ore heaps, enabling copper dissolution at ambient conditions.
- The technology targets mineralogically complex sulphides, extending leachability beyond conventional oxide-only heap leach feeds.
- Process flowsheet integrates bioleach solution collection with standard solvent extraction–electrowinning (SX–EW) for cathode production.
- Nuton® is designed to treat both run-of-mine ore and legacy waste/tailings, maximising metal recovery footprints.
- Environmental upside is centred on in-situ and heap processes, reducing need for new concentrator excavation and tailings dams.
- For other copper districts, Nuton® implies a potential re-rating of low-grade sulphide inventories and historic dumps.
Our Take
Nuton’s first 99.99% copper cathode at the Johnson Camp mine, noted in the related 4 December 2025 piece, signals that Rio Tinto is now moving its more than 30 years of sulphide bioleaching R&D into commercial-scale demonstration rather than lab or pilot-only work.
Within our recent copper coverage, relatively few items combine ‘Projects’, ‘Product’ and ‘Sustainability’ tags, so Nuton’s Arizona deployment positions Rio Tinto as one of the main large-cap operators testing low-impact processing routes for stranded or complex copper sulphide resources in the United States.
The association with Gunnison Copper and Excelsior Mining in the related article suggests Nuton could become a platform technology for multiple operators in Arizona, which would give Rio Tinto leverage in regional permitting and infrastructure discussions beyond its own asset base.
Prepared by collating external sources, AI-assisted tools, and Geomechanics.io’s proprietary mining database, then reviewed for technical accuracy & edited by our geotechnical team.
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