Scientists have developed a technology of extracting gold from electronic scrap like old mobiles. This can help them get tons of gold from simple waste that was deemed useless until now.
All the waste from old electronic devices, starting with phones and finishing with TV sets, is considered to contain about 7% of gold from the world’s storage. The metal is used when crafting circuit boards and helps conduct electricity.
There were ways to extract gold from such devices earlier, but they usually needed toxic materials to use. Those experiments also produced a huge amount of carbon dioxide into the atmosphere, which would add up to the pollution.
This way is deemed non-toxic and much easier than all the previous ones. The technology needs the scientists to put the circuits into a mild acid and wait for the metal to dissolve. Then they add an oily substance that contains the non-toxic compound that is not being names named. The compound isolates gold from the complex mixture of other metals, enabling extraction.
Academics believe that their discovery could be used to recover 300 tonnes of gold — worth tens of millions of pounds — a year.
The same method can also be used to salvage other metals including copper, zinc, palladium and platinum, which are all found inside mobile phones.
Professor Jason Love, of the University of Edinburgh’s school of chemistry, who led the study, said: “We are very excited about this discovery, especially as we have shown that our fundamental chemical studies on the recovery of valuable metals from electronic waste could have potential economic and societal benefits.”
He now wants phone companies and governments to improve recycling of mobiles so that the precious metal does not go to waste and to stop “backstreet” experiments to salvage gold.
He explained that although the gold from individual phones might only amount to a few milligrams, it was very valuable.
“The amount of gold might not be very much but it is a lot more than you would find in the ore,” he said.
“One tonne of ore would give you 100g of gold, while one tonne of phones would give you 300g. So there is a lot more gold in electronic waste that could be recovered. Europe doesn’t have its own gold mines and this is the potential for that. This is all urban mining”.
The same volume of discarded mobile phones contains about 100kg of copper and 3kg of silver, among other metals.
The study, published in the journal Angewandte Chemie, was funded by the Engineering and Physical Sciences Research Council. The researchers have yet to establish which phone is the most valuable but believe that the more metal the better, so slim smartphones could be less valuable than their more humble predecessors.
With gold prices at £1,000 an ounce, recycling has become even more important. It has spawned a new industry called urban mining, which involves recycling scrap metal from old electronic products in search of gold and other precious metals such as iridium.
The materials recovered are reused in new electronics parts or melted down and sold to jewellers, investors and manufacturers who re-use gold in the circuit boards of mobile phones.