Special Report: De Grey Mining has achieved gold recoveries of as high as +94 per cent from its Pilbara project, which likely means lower costs.

Testwork done on mineralisation at the Pilbara Gold Project has demonstrated average recoveries of between +90 per cent and +94 per cent and fast extraction rates of between six and 24 hours.

Importantly, De Grey has proven that it can achieve +90 per cent recoveries from the sulphide material at the Withnell deposit.

When the company struck the deal over the project in 2017, it inherited the challenge of finding a way to get the recoveries to such a high level as there was “market” opinion that all the sulphides would be a challenge on recoveries.

“This is a critical and positive step change in our efforts to further de-risk the project,” technical director Andy Beckwith told Stockhead.

“The plus 90 per cent recovery on the Withnell sulphide mineralisation is an outstanding improvement making Withnell a fundamental long-term baseload to the project.

“We are increasingly more confident that Withnell will also provide a long term high-grade underground mining opportunity.”

The high gold recoveries were maintained at a coarser grind size and we have been able to remove any need for a fine grinding circuit, which significantly reduces grinding requirements and the likely associated power costs.

A simplified process flowsheet is now being developed, with GR Engineering Services refining plant design, layout and costings.

As part of the process, De Grey will re-evaluate pit optimisations and the potential for a high grade underground mine below the Withnell pit.

“The simplified processing flowsheet, rapid extraction times and reduced grinding requirements, together with on-going exploration success, point to a significantly enhanced operation,” Mr Beckwith said.

“We are currently assessing the optimal project size.”

The Pilbara gold project already has a hefty 1.4-million-ounce resource, but De Grey’s focus remains steadfast on increasing that further and assessing the economic potential of the project.

The company is targeting 2.0Moz by the end of 2019 with 3.0Moz target thereafter.

The project, located around 60km south of Port Hedland in Western Australia, hosts over 200km of mineralised shear zones within the vast 1500 sq. km landholding.

De Grey Mining’s Pilbara Gold Project – Supplied

De Grey has set itself the goal of defining a significant development production profile greater than 100,000 ounces per year of gold production, sustained by a seven year mine life.

The company has a jampacked exploration program for this year, starting with resource extension drilling at the larger growth deposits – Withnell, Toweranna, Mallina and Mr Berghaus.

Diamond drilling has been underway at the Withnell deposit since mid-January. Meanwhile, a reverse circulation “RC” rig is due to shortly commence work at the Toweranna deposit.

The step-out drilling programs will focus on expanding open pit resources and to test deeper underground mineralisation at Withnell.

On top of that the company is working through the important economic studies.


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