De Grey Mining Achieves High-Grade Gold Recoveries at Hemi

THE DRILL SERGEANT: De Grey Mining (ASX: DEG) reported results from initial metallurgical testwork from the company’s Hemi gold deposit, located south of Port Hedland in Western Australia.

De Grey Mining undertook initial metallurgical testwork on mineralisation from the Brolga Zone, which achieved excellent gold recoveries of:

Oxide: 93 per cent based on CIL leach; and
Fresh: 96.3 per cent based on sulphide flotation, oxidation and CIL leach.

The company explained the testwork flowsheet comprised a conventional carbon in leach (CIL) circuit to treat oxide mineralisation.

“The gold recovery achieved in the initial metallurgical testwork of oxide, transition and fresh mineralisation at Brolga is very encouraging,” De Grey Mining managing director Glenn Jardine said in the company’s announcement to the Australian Securities Exchange.

“The testwork significantly de-risks the potential development of Hemi as a Tier 1 gold project in a Tier 1 jurisdiction.

“The testwork flowsheet used for Hemi can also be applied to De Grey’s other regional resources in the Mallina Basin.

“Hemi is a growing resource and contains a combination of oxide, transitional and fresh sulphide mineralisation.

“We will continue to increase our understanding of the scale and metallurgical properties of each of these domains across the deposit with ongoing testwork.

“Hemi’s excellent location, along a major transport, gas and power corridors, all within 60 kilometres of Port Hedland, is a major advantage for a Tier 1 gold resource and development project.”

The flotation circuit generated a gold-rich sulphide concentrate that was oxidised using pressure oxidation (POX) that represented approximately 10 per cent of the ore feed to the flotation circuit.

Oxidised flotation concentrate from the POX circuit was treated by CIL to recover gold.

The company indicated it would assess other methods of oxidation during ongoing test work.