From urban mining to green mining

From 1970 to 2015, the annual gold production rate doubled and has remained at this high level ever since – with a slight upward trend. This, however, is not the only reason why recycling the precious metal has become increasingly important. Recycling helps reduce the ecological footprint of gold production significantly. While extensive recycling of gold from old jewellery, coins or residues from the chemical industry has long been a matter of course, the possibilities of recycling gold from e-waste are far from exhausted. This might change shortly.

Bacteria reduce CO2 emissions in urban mining

Recovering gold from old smartphones, computer circuit boards and scrap cars is significantly eco-friendlier than conventional mining, even if the yield seems small. Only about 100g of gold can, for example, be recycled from one tonne of computer circuit boards, which is why only about 15 per cent of the recyclable gold is thus far recovered from e-waste. Although companies specialised in recycling, such as Umicore, have optimised their processes regarding CO2 emissions, the energy consumption of urban mining in many cases remains significant. This problem could be solved with the help of the “cupriavidus metallidurans” bacterium, which makes it possible to recover gold from e-waste without the use of toxic chemicals, and with significantly reduced CO2 emissions. This innovative recycling approach is based on the scientific study of how gold nuggets actually come into existence in nature.

Nature as a blueprint: green mining

The German entities Brain Biotechnology and Cyplus, a company specialising in mining chemicals, have brought the use of bacteria in urban mining to market maturity. So far, however, their application has been limited to smartphones and computer circuit boards. The idea for so-called green mining is not entirely new: as early as 2010, the Finnish mining company Talvivaara used bacteria for the eco-friendly mining of nickel and zinc. In principle, cupriavidus metallidurans is also a suitable means for transforming conventional gold mining into so-called bio mining.