New approach to transform mining
Valuable metals can be mined with electricity rather than by digging holes and tunnels, new research reveals. This revolutionary technique uses less energy, minimises waste and even makes it possible to recover material previously regarded as beyond reach.
For thousands of years, humans have used traditional mining techniques involving sinking tunnels or large pits to recover relatively small amounts of useful metals like gold and copper. What remains is usually, at best, a scar on the landscape, large amounts of waste material, and habitat destruction. At worst, the practices have led to environmental catastrophes.
Now an international team, including researchers from the University of Western Australia, have found a way to harness the power of electricity to achieve the same mineral recovery but without the environmental costs.
By placing electrodes into rocks containing precious metals, the researchers use an electric current to push through chemicals that dissolve and extract the metals locked up inside. This allows the metals to be retrieved with minimal disturbance to the ground surface.
“Since the Bronze Age, essentially mining means that you have to dig up the ground and you have to process huge amounts of overburden material just to get to a tiny fragment, for example of copper or gold, and then you have to extract the copper or gold from that huge amount of material and then you are left with a lot of waste material,” says Henning Prommer, one of the authors of the study from The University of Western Australia and CSIRO.
Prommer describes the new approach as “something that is much more like keyhole surgery that we drill down to where the copper or gold is actually sitting deeper in the Earth and we don’t need to really dig up all that material that ends up being waste.”
At the moment, the question of the scalability of the technique has progressed only as far as computer simulations. Nevertheless, these show that the approach looks viable for a real mine site and would dramatically change the way we recover valuable metals and minerals. And if the electricity used to power the project is from renewable sources, the carbon footprint of the mining industry, which currently accounts for hundred of millions of tonnes of emissions per year, could be cut dramatically.
And there may be another advantage to reliance of renewables: a common “downside” of green sources like wind turbines is that the energy often “pulses”. But Prommer points out that, for this new technology, what some regard as a nuisance might actually be a bonus because there are “indications that some sort of pulsing current might even be helpful.”
Prommer is hopeful that this technology will greatly improve mining in the future. “It is a concept that could really change the way mining works and so that’s just part of the changes in how our whole society is going to operate and changes that we are going to see over the next few decades.”