Confirmatory metallurgical testwork conducted by SXG in early 2012 delivered excellent results, and showed that the oxide deposits are forecast to achieve overall metallurgical recovery of 95%. Gravity recovery accounted for approximately 60% of the overall gold recovery in the confirmatory testwork.
In addition, the testwork demonstrated that gold recovery in the cyanide leaching phase was rapid and was not sensitive to grind size providing the opportunity for increased plant throughput in future for modest additional capital.
Metallurgical testwork was conducted by AMMTEC under the supervision of METS and by Gekko. The testwork was conducted on samples collected from diamond drill holes into the deposits that were completed during 2011.
The anticipated process flow sheet (see diagram above) is based on the metallurgical testwork and represents a typical free milling carbon-in-leach (CIL)/carbon-in-pulp (CIP) gold processing circuit comprising:
- Two stage crushing;
- Single stage milling designed for a grind size of 105 micron;
- Gravity recovery;
- CIL/CIP leaching and adsorption with a retention requirement of only 16 hours;
- Elution, gold smelting and carbon regeneration;
- Tailings disposal.
The modular nature of the proposed process plant layout will allow for modifications, including increasing plant throughput, to be undertaken. The Sandstone plant has produced up to 90,000 ounces of gold per annum highlighting the potential to increase gold production for minimal additional capital cost.
Metallurgical testwork demonstrates excellent recoveries through conventional CIP/CIL processing. Gravity recovery from the Battler deposit is between 30 and 40% of the overall recovery. In addition, previous metallurgical testwork on the primary mineralisation at Python achieved a gravity recovery of between 28 and 63% and an overall recovery of between 96 and 98%.
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