DRAGOON, Ariz.—In the boulder-strewn desert east of Tucson, miners are using sulfuric acid and bacteria to bring online the first new U.S. copper production in more than a decade.
The metal is coming from Gunnison Copper’s Johnson Camp mine, where excavation stopped in 2010 when the previous owners reached ores that weren’t rich enough to profitably process. It is being restarted in partnership with Rio Tinto’s Nuton venture, which uses microbes to strip copper from ores that are otherwise uneconomical to mine.
Advances in mining technology, insatiable demand for the metal that is essential to everything electric, and President Trump’s push to boost U.S. raw-material output have made it worthwhile to revisit old mines and marginal deposits around copper-rich Arizona.
Johnson Camp is one of several copper projects racing to production in the state. Most plan to use heap-leaching technologies to produce ready-to-use slabs of copper, called cathodes, without expensive and energy-gobbling concentrators, smelters and refineries.
The U.S. has plenty of copper in the ground, but smelting capacity is a pinch point. A big chunk of U.S. mine output is shipped abroad and sent back in processed forms that manufacturers can use.
“About 50% of our total consumption is being imported because we’re not making enough,” said Craig Hallworth, Gunnison’s finance chief. “This could go a long way to fixing that.”
Gunnison started selling cathodes made using conventional heap-leaching methods of Johnson Camp’s oxide ores in September. The first batch of copper extracted from its sulfide ores using the Nuton technology is expected in the coming days. Ramped up, Johnson Camp should annually produce 25 million pounds of cathode.
The timing is auspicious. Copper prices have notched record highs this year and are expected to keep climbing.
Miners anticipate soaring copper demand to produce electric vehicles, renewable energy and data centers—not to mention all the wiring and plumbing needed to keep pace with population growth and rising living standards in the developing world.
Industry executives are bracing for copper consumption over the next 25 years that could exceed all of the copper that humanity has used until now.
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