Great Boulder Resources (ASX:GBR) has achieved an important de-risking milestone for its Side Well gold project, with metallurgical testing of ore from the Mulga Bill deposit achieving gold recoveries of up to 98.7% with moderate cyanide consumption.

The testing involved gravity recovery and cyanide leaching across a range of samples from Mulga Bill – covering multiple mineralisation styles, and including areas with copper grades of up to 6,483 parts per million (ppm).

It resulted in strong gold recoveries, with a low proportion of cyanide-soluble copper, and low cyanide-soluble chalcopyrite being the dominant copper mineral in four of the five sample parcels.

For the 668,000-ounce Side Well project, this was an important step, demonstrating Mulga Bill’s aptitude for conventional gravity recovery and cyanide leaching processing methods (as used by neighbouring gold mills).

Managing director Andrew Paterson said the test work was a boost for both the project and Great Boulder shareholders.

“The results of our metallurgical test work demonstrate Mulga Bill leached extremely effectively and is therefore amenable to standard cyanide leaching,” he said.

“This means it can be processed through a conventional gold plant or any of the existing gold plants in the Meekatharra region.

“This is a hugely important outcome, as it removes one of the last remaining questions around potential mine development at Side Well.”

He continued: “Mulga Bill has the majority of gold ounces known to date so it will always be the engine room of any mining operation here, and hence we’re extremely pleased and excited with this outcome.”

Great Boulder shares have performed strongly since the news, and at 14:02 AEDT, they were trading at 4.8 cents per share – a rise of 2.13% since the market opened.

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