New “greener” mining discovery sucks metals up


Photo by Ryan Beltz on Unsplash.

A new “environmentally friendly” mining technique that pulls heavy metals out of the ground using electrical currents has been discovered by scientists.

University of Western Australia researchers say they have developed a way to extract copper from the ground by pumping in a liquid chemical to dissolve ore and then using electrodes, like a magnet, to pull up the metals.

UWA geochemist Dr Henning Prommer said the technique is more sustainable than traditional methods using excavation and would allow mining companies to access underground metals that may be unreachable and with less waste production.

“The principle idea of this technique is that we can apply a direct current between two electrodes that are installed into an ore body within the deep subsurface,” Dr Prommer said.

“The electric potential that is then induced by the electric current is used to facilitate the transport of specific chemicals from one electrode over the distance of several meters towards the electrode of opposite polarity.”

Diagram showing how the new electrokinetic in-situ leaching mining technique works. Picture credit: UWA

The research team, which also includes experts from the Camborne School of Mines, the Commonwealth Scientific and Industrial Research Organisation (CSIRO) and the Technical University of Denmark, found the chemicals help both break down the ore and transport it for harvesting above the ground.

Dubbed the keyhole surgery of mining, this new technique is called electrokinetic in-situ leaching and can be powered by renewable energy. Researchers say it reduces pressure on the environment by taking away the need for tailing damns.

Murdoch University extractive metallurgy Professor Gamini Senanayake said while in-situ leaching is less costly, it does present some risks to the environment.

“More care has to be taken when using in-situ leaching to ensure you are not contaminating the surrounding water bodies,” Professor Senanayake said.

Mark Richardson from the WA Department of Mines, Industry Regulation and Safety said the mining technique was “new” and “exciting”.

He said the department supports sustainable and environmentally-friendly mining, but he refused to comment further on the technique because more studies were needed.

Dr Prommer is working on a follow-up project and undertaking further research supported by the Minerals Research Institute of Western Australia and four other mining companies.

“It could still be almost 10 years until we see a “real” mine using electrokinetics,” Dr Prommer said.

“We do not expect that the technology can replace traditional mining completely, but we hope that we can start with applications that appear to be “low hanging fruit” and go from there”.