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- De Grey Mining (DEG) receives results for two important process flowsheet selections for its Mallina gold project, including the Hemi Deposit, in Western Australia
- The flowsheets are the outcome of a nine-month trade-off study into the preferred process design for the project by pre-feasibility study (PFS) process engineer Wood Australia
- De Grey says process flowsheet selections — comminution circuit and oxidation circuit — represent the best technical, environmental and economic outcomes for its plant
- Each of the flowsheets represents key inputs into a planned PFS for Mallina, which is due in the September quarter of 2022
- De Grey shares are up 1.26 per cent and trading at 96 cents per share at 12:42 pm AEST
De Grey Mining (DEG) has received results for two important process flowsheet selections for its Mallina gold project, including the Hemi Deposit, in Western Australia.
The flowsheets are the outcome of a nine-month trade-off study into the preferred process design for the project by pre-feasibility study (PFS) process engineer Wood Australia.
De Grey said the process flowsheet selections — comminution circuit and oxidation circuit — represented the best technical, environmental and economic outcomes for a proposed plant of this scale.
The comminution circuit process is a three-stage crushing using high-pressure grinding rollers (HPGR) followed by conventional ball milling based on a 10-million-tonne-per-annum (tpa) processing plant throughput.
The oxidation circuit process refers to pressure oxidation (POx) at a rate of 800,000 tpa throughput to oxidise gold-bearing sulphides after flotation.
“HPGR and POx are robust, well-proven and accepted technologies that have been chosen after extensive testwork,” De Grey Managing Director Glenn Jardine said.
“Pressure oxidation demonstrated lower reagent usage and carbon intensity, lowest greenhouse gas emissions and the highest gold recovery of the processing options considered for Hemi mineralisation.”
The Wood Australia trade-off study confirmed Hemi mineralisation had “excellent” recovery and was amenable to HPRG and POx processing technologies.
De Grey said these process routes had advantages such as lower capital and operating costs, higher gold recovery, 20 per cent lower energy consumption and 25 per cent lower carbon dioxide output.
Additionally, the flowsheet selections have the benefit of lower carbon emissions through lower energy requirements and lower greenhouse gas emissions.
Each of the flowsheets represents key inputs into a planned PFS for Mallina, which is due in the September quarter of 2022.
De Grey shares were up 1.26 per cent and trading at 96 cents per share at 12:42 pm AEST.
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