We partnered with the world's largest gold producer, Barrick Gold, to develop a tailored solution that uses a non-toxic chemical to replace cyanide in gold recovery. It's enabled the company to maintain productivity at their Goldstrike mining operation in Nevada, USA.

The challenge

Increasingly lower grade and complex ores

Recovering gold without cyanide would help reduce environmental impacts and help Barrick Gold maintain production at Goldstrike Mine.

Gold producers are increasingly challenged by reducing ore grades, more complex ores and increasingly stringent environmental regulations.

The world's largest gold producer, Barrick Gold, was faced with changes in the ore they were mining at their Goldstrike mine in Nevada, USA.

The nature of the Goldstrike orebody was becoming increasingly complex and a new process solution was needed in order to cost-effectively maintain production rates.

Our response

A cost-effective, more environmentally-friendly alternative

Working with Barrick Gold, we developed a niche, tailored gold recovery process for use at their Goldstrike mine.

We came up with a novel gold recovery process that replaces cyanide with thiosulphate – a non‑toxic chemical that helps to reduce environmental impacts.

Thiosulphate is effective at picking up gold in leach tanks to create a gold‑thiosulphate complex. The gold can be separated from the thiosulphate using ion exchange resins in what has traditionally been a challenging process. Working to improve this separation process, we discovered that adding sulphite as an additive to the ion exchange resin enabled easier separation.

The thiosulphate process is appropriate for the treatment of high-grade gold concentrates, and could also be valuable for use in other applications. For example, in-situ leaching in deep mines and for use in treating gravity gold concentrates, particularly those with high cyanide-soluble copper.

The results

Improving productivity at Goldstrike mine

Barrick Gold has commercialised a tailored thiosulphate leaching process that it's using at its Nevada Goldstrike mine.

It has enabled the Nevada mine to maintain production despite the changing nature of the orebody being mined and is expected to contribute an average of 350,000 to 450,000 ounces of gold a year over the first five full years.

Replacing cyanide with the non-toxic thiosulphate will reduce the risks and environmental impacts of gold processing and may open up opportunities in areas where the use of cyanide is banned, including some states in Australia, several European countries and several US states.

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