Scientists from Flinders University (Australia) developed an innovative technology for recovering gold from ore and electronic waste including circuit boards of old computers and other appliances. This new technology allows to receive high-purity gold with the minimal harm for human health and environment.
In the study published in Nature Sustainability journal the team headed by Professor Justin Chalker presented a universal approach to recovering gold from different sources — from ore concentrate to scientific and industrial waste. The method is based on the leaching agent on the basis of trichloroisocyanuric acid — the compound which is broadly used for disinfecting water. In combination with salted water this agent effectively dissolves gold without application of hazardous substances such as cyanide or mercury.
At the next stage, gold is recovered from the solution using a specially created polymer containing sulfur. This sorbent agent selectively binds gold particles even in complex mixtures such as electronic waste. After that the polymer may be decomposed down to initial monomers to release the gold, and then re-use the material. This approach makes the process not only efficient, but environmentally sustainable.
The study puts a special focus on using the gold mining technology. Traditional methods of gold extraction are often connected with serious environmental and medical risks. Mercury is still used at small and primitive mines to turn gold into amalgam. Then mercury evaporates due to heating and the gold remains, however, toxic vapors are emitted into the ambient air. According to the World Health Organization, up to one third of all the miners suffer from mercury vapors poisoning. Such mines account for about 37% of the world mercury contamination, they are the major source of releases of this hazardous metal. The new technology of leaching and sedimentation of gold may become a reliable alternative for smaller and medium-size mines, especially for the countries where goldmining plays an important role in national economy. This method has already been tested in real conditions by the cooperative team of the US and Peru scientists.
On top of the mining sector, the technology may be used to resolve the global problem of processing electronic waste, the volumes of which are growing constantly. In 2022, 62 million tons of such waste were generated globally, but only 22.3% of them were processed. Electronic appliances contain hazardous substances (lead, mercury, dioxins), and in case they are not properly processed, they may constitute a serious threat for human health and for the environment. The new technology provides a solution: the first tests with electronic waste demonstrated encouraging results.
In the near future, the Australian scientists team intends to conduct joint field tests of this technology together with mining companies and electronic waste processing companies.
