Recovering valuable metals from mine waste

A groundbreaking study reveals that acid-producing bacteria can dissolve and recover valuable metals like magnesium from mine waste, potentially reducing environmental hazards and providing raw materials for industrial use.

Researcher Nathan van Wyk at the Linnaeus University highlights the method's promise in mitigating pollution, extending mine lifespans, and addressing the growing demand for rare earth elements.

Mine waste, often discarded in large quantities, poses significant environmental risks by leaching harmful metals and chemicals into groundwater. However, this waste also contains untapped reserves of useful metals. Van Wyk’s research focuses on extracting these metals through bacterial acid dissolution, with impressive results. His study demonstrated nearly 100% magnesium recovery from magnesium-rich residues, alongside significant extraction rates for aluminium (68%), calcium (80%), titanium (59%), and rare earth elements like yttrium (42%) from bauxite residues, a by-product of aluminium production.

This innovative approach not only addresses the environmental dangers posed by mine waste but also offers a sustainable method for sourcing critical materials needed for various industries, paving the way for cleaner and more efficient mining practices.

New opportunities

“Acid dissolution of mine waste is a promising way to make use of valuable resources. It reduces the amount of waste, protects nature, creates raw materials for industry and extends the life of the mines. And also advances ‘green’ technology while providing jobs. There are many advantages to this method, rather than just leaving the waste behind,” said Nathan.

A positive side effect of the method is that any residual material can be combined with cheap additives to produce a type of rapid curing concrete.

“With the waste from our process, we can make construction material, like concrete. Our concrete doesn’t need to be calcinated (an energy intensive process) during production as the energy had already been spent. Over 7% of all the energy used in industry globally is used for the production of concrete and cement. So by using this waste we can achieve zero solid waste, and reduce global energy consumption, to a degree,” said Nathan.

Nathan believes that the acid dissolution method needs some development to achieve large-scale production, but lab scale work reveals an elegant and effective process, and he hopes it will be implented by the mining industry in the future.

“We have developed a new technology that has several applications within the mining industry. Through this technology, we can create mining operations into a zero-waste facility,” he added.