Biological oxidation is a pre-treatment technique used to liberate gold from refractory auriferous sulfide minerals such as arsenopyrite and pyrite. During this pre-treatment process, secondary sulfate minerals (e.g. jarosite) may be formed which renders sulfide-liberated gold unavailable for leaching, and also diminishes the effectiveness of further oxidation processes. Previous studies by the author have shown that, the presence of secondary sulfate minerals, particularly jarosite encapsulation, led to poor gold extraction from the bio-oxidised concentrates obtained from the Ghanaian gold province. This poster investigates the influence of cyanide and oxygen concentrations on the gold leaching efficacy of the jarosite-bearing bio-oxidised flotation gold concentrates. From the results, it was evident that increasing cyanide concentration from 1 kg/t to 5 kg/t led to about double the gold extraction (from 29 wt.% to 71 wt.%). Mineralogical studies of the leached feeds and solid residues using semi-quantitative X-ray diffraction (XRD) showed a reduction in the jarosite content as higher cyanide concentrations were deployed for the leaching process. Corresponding effects on reagent consumption coupled with pulp interactions and literature have been highlighted and discussed.
CITATION:Asamoah, R K, Skinner, W and Addai-Mensah, J, 2019. Effect of Cyanide Concentrations on Leaching of Jarosite-Bearing Bio-oxidised Flotation Gold Concentrates, in Proceedings MetPlant 2019, pp 383388 (The Australasian Institute of Mining and Metallurgy: Melbourne).