Good news!
"An interdisciplinary team of experts in green chemistry, engineering and physics at Flinders University in Australia has developed a safer and more sustainable approach to extract and recover gold from ore and electronic waste. ..."
"The glistening gold-extraction technique, ... promises to reduce levels of toxic waste from mining and shows that high purity gold can be recovered from recycling valuable components in printed circuit boards in discarded computers. ...
Around the world, artisanal and small-scale gold miners use mercury, which binds to gold particles in ores, to create what are known as amalgams. These are then heated to evaporate the mercury, leaving behind gold but releasing toxic vapours. Studies indicate that up to 33% of artisanal miners suffer from moderate metallic mercury vapor intoxication. ...
“The study featured many innovations including a new and recyclable leaching reagent derived from a compound used to disinfect water,” ...
“The team also developed an entirely new way to make the polymer sorbent, or the material that binds the gold after extraction into water, using light to initiate the key reaction.” ..."
"... A final innovation is to recycle the sorbent. Here we relied on a linear poly(trisulfide) that can be “un-made” by depolymerization. This capability allows simultaneous gold recovery and monomer recycling. We are particularly proud of developing this polymer because it was originally thought to be inaccessible. Our photo-chemical polymerization in a flow reactor overcame this challenge to provide that key material. ..."
From the abstract:
"Gold plays an essential role in the global economy and has wide applications in various industrial technologies.
Currently, the gold supply relies heavily on mining processes that employ toxic substances such as cyanide salts and mercury metal, leading to substantial environmental pollution.
Gold extraction approaches that do not rely on cyanide and mercury are needed to improve the overall sustainability of gold production.
Here we develop an approach for gold leaching and recovery from ore and electronic waste. This approach first uses trichloroisocyanuric acid, activated by a halide catalyst, to oxidatively dissolve gold metal from ore and electronic waste, and then applies a polysulfide polymer sorbent to selectively bind gold from the leachate.
The gold can be recovered in high purity by pyrolysing or depolymerizing the sorbent. The efficacy of this approach in gold extraction was validated using ore, electronic waste and other gold-containing waste. Overall, this work provides a viable approach to achieve greener gold production from both primary and secondary resources, improving the sustainability of the gold supply."
Golden opportunity to reduce toxic waste (original news release)
Sustainable gold extraction from ore and electronic waste "Our team has developed a sustainable method for gold extraction. Our goal is to reduce the impact of gold mining on the environment and human health, providing safer alternatives to cyanide and mercury in mining."
Sustainable gold extraction from ore and electronic waste (no public access)
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