CSIRO goes for non-toxic gold

THE CSIRO has licensed to a gold miner a non-toxic production technique that it says could double output for smaller producers.

In development for a decade, the “Going for Gold” process can replace the cyanide-based method of extracting gold from ore, Australia’s national science agency says.

It uses the non-toxic chemical reagent thiosulphate.

“We’re pretty excited about it, but we don’t expect it to replace cyanide throughout the industry,” CSIRO research program leader Chris Vernon said.

Cyanide would remain a “quick and easy” method of gold processing for big companies with the capability to handle the poisonous chemical, Dr Vernon said.

But the “Going for Gold” technique could be useful for smaller companies that relied on gravity separation, he said.

The new leaching technique recovered the tiny gold particles that were lost during gravity processing, although it was also more expensive, Dr Vernon said.

“I think it will be significant for the small to mid-sized miners, because it does give them more options,” he said.

Using thiosulfate for gold leaching was not a new idea but the CSIRO found ways to overcome problems involving oxidation and make it work, Dr Vernon said. The CSIRO had been working on the problem for about 10 years.

Perth-based Clean Mining Limited has licensed the technology and is in negotiations with ICA Mining Services in the Northern Territory to commission the first commercial plant using it, as well as with Nu-Fortune Gold to commission a plant in the West Australian 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 was processed using cyanide or mercury, and once the chemicals were used, they were often held in large tailing dams that could leach or burst.