Oxidation Behaviour and Bio-oxidation of Gold-bearing Sulphide Ores: Oxygen Capabilities and Challenges

Abstract

The paper presents an overview of bio-oxidation of sulphidic refractory gold ores prior to gold cyanidation. This review discusses several factors, more importantly, oxygen requirements and oxygen limitations in biological oxidation of various sulphide minerals associated with gold ores. The availability of sufficient oxygen in bio-oxidation systems can speed up and enhance the oxidation of sulphide minerals, allowing the gold to be liberated for further extraction. However, oxygen supply and its low solubility in water have been the major limiting factors in bio-oxidation processes. More importantly, oxygen limitations are found to affect the rate of sulphide oxidation and the volume of materials that can be treated for gold leaching. First, the paper discusses the influence of dissolved oxygen on the oxidation behaviour of various sulphide minerals found in refractory gold ores or concentrates. Further discussed are the limiting factors in relation to dissolved oxygen during bio-oxidation of refractory gold ores. This review demonstrates that oxygen availability is a major challenge and therefore, oxygen enhancement techniques or strategies are vitally needed. As well, the review serves to inspire new research into efficient strategies to enhance oxygen availability.