Toweranna a ‘game changer’ for De Grey with high gold recoveries
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Special Report: De Grey Mining’s Pilbara gold project just keeps delivering the goods, with recent test work yielding high recoveries from low-cost, simple processing.
The test work produced high recoveries of 94.7 per cent for oxidised rock and over 96.3 per cent for fresh rock from the Toweranna deposit.
This means the Toweranna deposit is free milling and fully amenable to conventional, low-cost carbon-in-leach (CIL) processing.
Separate samples were also tested for gravity recovery, with oxide and fresh rock samples returning recoveries of 20.8 per cent and 54.3 per cent respectively.
The high levels of gravity gold indicate that it may be possible to lift total gold recovery by installing a gravity concentrator ahead of the CIL circuit.
The merits of employing gravity extraction will be further evaluated in subsequent test work.
Technical director Andy Beckwith said Toweranna continued to grow in stature with strong resource growth potential and high recovery with conventional CIL processing characteristics.
“Ongoing drilling results continue to define multiple stacked lodes to at least 200m depth,” he said.
“We are increasingly seeing free gold in the veins in core and the high gold recovery together with the simple free milling nature is encouraging.
“Toweranna is poised as a game changer as it has the potential to rapidly increase resources and improve the PFS economics.”
Once the latest drilling results are finalised, De Grey plans to update the open pit resource and run optimisations.
Earlier this week, De Grey revealed it had found more high-grade goldfrom another 17 holes drilled at the Toweranna deposit.
The Toweranna deposit may only be the tip of the iceberg.
De Grey is currently completing a pre-feasibility study for the broader Pilbara project, and is aiming to boost resources to 2 million ounces, from 1.4 million ounces currently, by the end of 2019. The bulk of the new ounces may come from Toweranna.
The company is accelerating its efforts to expand resources down to 200m and test mineralisation down to at least 600m.
A resource update is scheduled for the September quarter.