Refractory Gold Ores And Concentrates Part 1: Mineralogical And Physico-Chemical Characteristics

A comprehensive mineralogical and physico-chemical examination of two refractory gold ores and concentrates from the Ghanaian gold province was conducted to gain a better understanding of the differences in performance of gold cyanidation. Both ore were mainly silicates, carbonates, oxide, phosphate and sulphides. Flotation of the ground ores produced concentrates with noticeable differences. Whilst both mainly contained sulphides and silicates, apatite was present in one flotation concentrate and dolomite in the other. Biooxidation of the apatite-bearing concentrate produced jarosite-bearing bio-oxidised product. Bio-oxidation of the dolomite-bearing concentrate yielded a jarosite-free bio-oxidised product with lower bassanite content but higher gypsum, graphitic carbon, and pregrobbing effect compared with the jarosite-bearing bio-oxidised product. The jarosite minerals appeared to aid gangue mineral agglomeration and also encapsulated auriferous minerals which attenuated the bio-oxidation process and reduced gold extraction.