Researchers remove cyanide from gold leaching process – Australian Mining


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Researchers from Curtin University have delivered a technology that will significantly enhance the leaching rates for gold ore without using cyanide.

Currently, the industry is needing higher temperatures, glycine concentrations oxygen addition levels when leaching gold with glycine in the absence of cyanide.

An eight-year study by Curtin University has led to an improved glycine leaching technology that eliminates the above issues.

It uses a low concentration of a strong oxidising agent known as potassium permanganate, which produced the most successful results compared with other oxidants for the alkaline glycine gold leach system, according to co-research lead chair for extractive metallurgy for the Future Battery Industries Cooperative Research Centre (FBICRC) Jacques Eksteen.

“Traditionally, leaching or separating gold other precious metals from an ore deposit or e-waste materials requires the use of cyanide – a highly toxic chemical compound that is known to have detrimental effects to the environment to the human body,” he said.

“Industrially, it is very expensive to detoxify cyanide, but it still does not eliminate the risks associated with transporting, hling processing the chemical.”

Cyanide’s toxicity, glycine was naturally produced by the human body, he added.

With low concentrations of potassium permanganate being added to the glycine system, the researchers were able to leach 85.1 per cent of gold from the ore deposit at ambient temperature.

Co-research lead senior research fellow Elsayed Oraby said researchers at Curtin University had spent years developing a new leaching process,
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