De Grey’s metallurgical test work has achieved high gold recoveries on ore taken across the Aquila zone at its Hemi project in WA’s Pilbara region. 

Overall metallurgical recovery of 94 per cent was achieved on a bulk composite of primary mineralisation grading 1.67 grams per tonne (g/t) gold that was put through a flowsheet of sulphide flotation followed by pressure oxidation of the flotation concentrate and cyanide leaching of the resulting residue.

Additionally, test work on individual composites of transition and primary mineralisation returned overall recoveries of between 89.8 per cent and 97.2 per cent using the same process.

Lastly, cyanide leaching of oxide mineralisation grading 1.08g/t gold achieved a recovery of 94.9 per cent after 24 hours.

De Grey Mining (ASX:DEG) managing director Glenn Jardine says the test work results from Aquila are encouraging and consistent with the results achieved from the Brolga zone.

“Our ongoing metallurgical test work program continues to provide confidence in the multiple pathways available to achieve high gold recoveries from Hemi and the regional deposits across the Mallina gold project,” he added.

“Each of the three potential oxidation processes has delivered high gold recoveries for the Brolga and Aquila zones.

“Further test work and trade off studies underway will enable the company to optimise the various aspects of our metallurgical test work program in terms of capital, operating costs, recoveries and operability.”

Aquila zone

The Aquila zone is located north of the large Brolga intrusion and is known to host strong gold-sulphide mineralisation.

Recent resource definition and extensional drilling at Aquila returned high-grade hits including 1m at 105.5g/t gold within a broader 11m at 10.5g/t gold interval from 51m.

Aquila has the potential to be combined with the Brolga and Crow zones as a large, bulk, open pit mine.



This article was developed in collaboration with De Grey Mining, 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.