The golden glow of e-scrap

Swiss researchers have discovered a new way to mine discarded electronics for gold.

ETH Zurich University is pioneering a ‘highly sustainable and hugely effective’ method to recover gold from e-scrap using a sponge of protein fibrils. Researchers derived the fibrils from whey, a by-product of the cheese industry.

Professor Raffaele Mezzenga, who leads the R&D project, reports 22-​carat gold nugget weighing 450 milligrams have been extracted from 20 computer motherboards.

His team dissolved the metal scrap in an acid bath to ionise the metals. When the researchers placed the protein fibril sponge in the metal ion solution, the gold ions adhered to the protein fibres. They observed the same effect with other metals, although gold was recovered most efficiently.

After this, they heated the sponge. This reduced the gold ions into flakes which were then melted into nuggets.

Mezzenga says the recovery method is commercially viable. The combined procurement costs for the source materials and the energy costs for the entire process are said to be 50 times lower than the value of the recycled gold.

The breakthrough has a double advantage, Mezzenga claims. ‘We are transforming two waste products into gold. You can’t get much more sustainable than that.’