More gold, less cyanide, Taking the tarnish off the gold recovery process

Melbourne researcher, Matthew Jeffrey, is developing a new technique that replaces cyanide with a non-toxic chemical to recover gold from ore bodies.

The non-toxic chemical, known as thiosulfate, is commonly used as a fixative in photography.

Dr Jeffrey’s current three-year research project will determine whether thiosulfate could be introduced into existing gold-processing plants, or whether they would need to be rebuilt.

Dr Jeffrey, a chemical engineer at Monash University, sees a direct environmental benefit from his research. “If this research is successful, cyanide spills may become a thing of the past. And the gold industry would become less of a threat to the Australian environment.”

“The Australian gold industry is currently under siege due to the use of cyanide during the processing of gold ores – a practice dating back 100 years,” explains Dr Jeffrey.

Although an efficient process, most forms of cyanide are toxic and pose a serious threat to the natural environment. A glaring example is the cyanide spill, due to the collapse of a gold mine tailing dam, at Baia Mare in Romania that killed large numbers of fish and wildlife in the Tisza and Danube Rivers.

Gold is an integral part of the Australian economy, being one of the country’s highest export earners. Gold production in the 2000-2001 fiscal year totalled $4.5 billion.

Dr Jeffrey’s research was aided by the use of a rotating electrochemical quartz crystal microbalance – an instrument that accurately measures how rapidly gold reacts with specific chemicals. “If that reaction doesn’t occur, we can’t recover gold from ore as metal.”

Dr Jeffrey is conducting this research with the support of the Australian Research Council and the Australian gold industry.

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