Study of the behaviour of Au in oxide ores during thiosulfate leaching

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The objective of this project is to develop a novel methodology to investigate the interactions between thiosulfate, complex ore samples and Au to better understand the complex behaviour that occurs during the industrial process of Au extraction called leaching. A novel ring-Au disk-mineral electrode will be fabricated to study Au and mineral interactions in the presence of thiosulfate and to study thiosulfate interactions with both Au and the mineral surface. Electrochemical techniques will be employed to study the Au leaching kinetics as well as the rate of formation of a passive layer that impedes the leaching kinetics in the presence of different minerals. Spectroscopic techniques will then be employed to identify the nature of the passive layer responsible for limiting the Au leaching kinetics. Using this ring-disk electrode we will identify the mineral(s) responsible for increased thiosulfate oxidation and passive layer formation. This knowledge is essential for the development of the ore pretreatment methodology mitigating these effects and increasing the Au leaching kinetics. Several additives to the lixiviant solution that have been previously identified to enhance Au leaching will be investigated in order to comparatively determine the role of each additive in the presence of different minerals. The information sought in this project will be essential for assisting the Canadian Au industry, specifically Barrick Gold Inc in development of new environmentally-friendly Au extraction processes.