New gold recycling introduced to WEEE
Monday, 19 December 2016
Researchers at the University of Edinburgh believe they’ve discovered a method for retrieving gold from electrical waste such as computers, televisions and older mobile phones.
Gold plays a key role in the construction of printed circuit boards found in these electrical devices, with as much as seven per cent of the world’s gold believed to be found inside them.
Research has shown that many of the current methods used for extracting gold aren’t as efficient as they could be and make use of toxic chemicals such as cyanide. A more efficient method of extracting the metals would therefore be welcome.
Scientists at the University of Edinburgh have developed such a method and they estimate that it could help salvage as much as 300 additional tonnes of gold each year.
The new process involves submerging the printed circuit boards in a mild acid which then dissolves all the metal parts. Then, an oily toluene solvent containing the primary amide is added: this selectively extracts the gold from the mix of other metals.
Professor Jason Love, from Edinburgh University’s School of Chemistry, claims that the process can help to retrieve gold mixed with water from the chemical mix.
“After separation of the oily phase from the acid phase, washing the oily phase with water transfers the gold into the water phase for electro-winning,” said Love.
“We have to do this a couple of times to ensure complete phase transfer, but each wash step is very quick.”
85 per cent of gold contained on the older circuit boards is extracted on the first pass of this process and Professor Love noted that repeating the process several times should lead to complete recovery of the metals.
These findings could represent a substantial breakthrough in terms of large-scale recovery of gold and other precious metals from waste electronic products.
“We…want to look into developing a whole process to satisfy a possible circular economy theme,” added Love.
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