Integrated biological process for complex sulphides

ABSTRACT An integrated biological process concept is described comprising two or more microbiologically assisted process steps for the treatment of sulphide ores or concentrates. Such an integrated process allows for the extraction of metal values and for the treatment of the corresponding waste streams for environmental disposal. Metal extraction from base metal ores is achieved through the use of sulphide-oxidizing bacteria such as T. ferrooxidans. For refractory sulphidic gold ores, the same bacteria can be used to liberate the precious metal from the sulphide host minerals for recovery by conventional methods such as cyanidation. In either case, a sulphate solution is generated which can be treated in a patented 2-stage anaerobic-aerobic biological process to produce sulphur and reusable water. For the processing of gold ores and concentrates, a further biological process can be effective for the degradation of free cyanide, thiocyanate and metal cyanide complexes in solutions remaining after the gold extraction step. The current state of the art in biological technology is described and potential applications for an integrated approach is discussed.