Could a virus spell the end of acid rock drainage? (Mining Technology – February 6, 2017)

Microbes play a huge part in mining, both good and bad. But thanks to a new study by the University of British Columbia, which successfully identified and isolated the microbes responsible for acid rock drainage, the good may soon outweigh the bad. Molly Lempriere finds out what microbes to look for.

Microbes are an intrinsic element of the mining process, bringing both beneficial and dangerous side-effects. Naturally occurring micro-organisms are inevitably exposed during excavation, causing chemical reactions that vary from site to site.

Companies as large as Vale and Rio Tinto have begun to use microbes to their advantage with biomining techniques that capitalise on waning resources as regulations tighten. Research into microbes at mine sites continues to yield benefits; one new study by the University of British Columbia (UBC) has managed to identify and isolate microbes involved in acid rock drainage (ARD). This will enable strategies to counteract the damaging effects of ARD, giving mine sites control over the microbes within them and further minimising the environmental effects of mining.

Microbes have been used to extract minerals since the 1950s, but the technique has only become commercially popular over the last few years as dwindling resources and high energy prices have pushed mining companies to look for alternative extraction methods.

Mining is a costly and energy-intensive process, which has increased following tightening of regulations on power consumption. This is exacerbated by the lower quantity of high-grade resources available. In the past, mines sought only resources of 5% or higher, whereas modern day sites often extract ores of grades as low as 0.5%.

Biomining is the process of extracting valuable metals from the reductive reactions of microbes. Already it has proven particularly successful in copper and gold, with an estimated 10%-15% of copper and 5% of gold worldwide produced using biomining.

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