Great Boulder says initial metallurgical tests on samples from the Mulga Bill prospect at its Side Well Gold Project in WA show positive gold recoveries.

More than 62% of gold was recovered in the gravity circuit – indicating a high portion of the gold present is coarse gravity recoverable gold.

Overall recoveries ranged from 87.2% to 88.0% after a 48-hour leach time and independent of grind size.

First step to determining economic extraction

Great Boulder Resources (ASX:GBR) MD Andrew Paterson says the test-work is an important first step in considering the future potential for economic extraction of gold from the Mulga Bill deposit. 

“These initial indications from metallurgical work on RC chips are very positive, particularly the very high percentage of gravity-recoverable gold and the apparent coarse nature of the gold,” he said.

“Obviously we’re also pleased to note Mulga Bill appears to be amenable to standard cyanide leach extraction as expected, with no indications of any refractory mineralisation.”

Further testing underway to improve recoveries

A fourth leach test is now underway to see if increased cyanide concentrations at 150 μm will improve overall recovery to >90%.

“We will also be doing more tests in future using different mineralisation styles, including samples of diamond core to gather more comprehensive data on potential milling characteristics,” Paterson said.

Diamond drilling at Mulga Bill is ongoing and remaining assays from 2021 RC and AC holes are expected during March.




This article was developed in collaboration with Great Boulder Resources Limited, a Stockhead advertiser at the time of publishing.


This article does not constitute financial product advice. You should consider obtaining independent advice before making any financial decisions.