CSIRO has licensed a nontoxic gold mining technique to a Perth company it says could double production for smaller gold producers.
In development for a decade, the “Going for Gold” process replaces the cyanide used to extract gold from ore with the non-toxic chemical reagent thiosulphate.
“We’re pretty excited about it, but we don’t expect it to replace cyanide throughout the industry,” said CSIRO research program leader Chris Vernon.
Cyanide will remain a “quick and easy” method of gold processing for big companies with the capability to handle the poisonous chemical but the “Going for Gold” technique could be useful for smaller companies that still rely on gravity separation, Dr Vernon said.
This new leaching technique recovers the tiny gold particles that are lost during gravity processing, although it’s also more expensive, Dr Vernon said.
“I think it’s be significant for the small to mid-sized miners, because it does give them more options.”
Using thiosulfate for gold leaching isn’t a new idea but CSIRO found ways to overcome problems involving oxidation and make it work, Dr Vernon said.
CSIRO has been working on the problem for about 10 years and ramped up work on it three or four years ago, he said.
Clean Mining Limited licensed the technology and is in negotiations with ICA Mining Services in the NT to commission the first commercial plant using it, as well as with Nu-Fortune Gold to commission a plant in the WA goldfields.
“The world has been waiting for a cost-effective, non-toxic solution to gold processing and, following the signing of this contract with CSIRO, Clean Mining now offers that solution,” said the company’s managing director, Jeff McCulloch.
About 75 per cent of gold extracted from ore is processed using cyanide or mercury, and once the chemicals are used they are often held in large tailing dams that can leach or burst, Mr McCulloch said.
“Eliminating cyanide and the associated tailing dams from the gold recovery process is a game-changer for the sector and, importantly, for the communities where gold miners operate,” Mr McCulloch said.
CSIRO tested the process with Clean Mining’s parent company, Eco Minerals Research Limited, for more than a year at a demonstration plant in the WA goldfield town of Menzies.
A Perth jeweller has even paid a premium for the non-toxic “green gold,” Dr Vernon said, citing the project as an example of CSIRO’s commitment to boost Australian industry and jobs.