Biomining: How microbes help to mine copper

Posted on Posted in Science News

Chile is the world’s biggest copper exporter, and has the planet’s largest known reserves of the red metal. Export of the metal is essential for Chile’s economy – it amounts to about 70% of all Chilean exports – and the more copper the country digs out, the more money pours in. 

As Pilar Paddar, research and development director of Biosigma (a biotechnology venture set up by Codelco, a Chilean state-owned corporation), walks past a weird-looking installation with wildly shaking flasks, she says the key to success is using microorganisms that are naturally present at mining sites. “These bacteria need very little to do their work, they use air and mainly oxygen and CO2, and use the mineral itself as a source of energy,” she says. She explains that if a mining site is left alone, microorganisms would eventually liberate copper from rocks, but it could take hundreds of years. To speed up the process in a biomining lab, scientists use bioleaching. Ores are placed into acid, and then researchers introduce bacteria that change the solution so that it dismantles the rock and frees copper, in liquid form. And after a special electrochemical process, it is then turned into solid metal that can be used in the industrial applications we so much depend on.

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