Report A5977 POX Testwork

This report details the evaluation of pressure oxidation combined with cyanidation to enhance gold extraction from a bulk sample of flotation concentrate provided by Fimiston. The primary objective was to assess the effectiveness of this combined processing method in improving gold recovery. Methodologically, the report outlines the procedures involving ultra-fine grinding of the concentrate, followed by pressure oxidation in an autoclave at controlled temperature and pressure, and subsequent cyanidation of the neutralized oxidation product. The results indicate that sulphide oxidation exceeded 99%, and gold extraction performance reached an impressive 97.6%. Specifically, the leach residue analysis demonstrated low gold content post-process, suggesting efficient gold recovery. Additionally, the neutralization process indicated a substantial reagent usage, consuming 492 kg of CaO per tonne of concentrate. Although the ability to optimize reagents was noted as outside the scope of this work, the findings provide valuable insights into the effectiveness of pressure oxidation and cyanidation in enhancing gold extraction from flotation concentrates.