Gold process modelling. II. The effect of ore type on leaching and adsorption dynamics at telfer gold mine

The process of gold cyanidation and Carbon-In-Pulp/Carbon-In-Leach (CIP/CIL) is used extensively worldwide for the recovery of gold from ores. A continuous CIP/CIL model can be used to predict outcomes from the CIP/CIL processing of different ores, or for evaluating the effects of non-idealities in CIP/CIL circuits, such as preg-robbing. In this paper a CIP/CIL model was developed which accounted for the leaching of gold from the ore, preg-robbing of gold onto the ore surface and adsorption of leached gold onto activated carbon. A variable order Mintek model was used to model the kinetics of gold leaching. A film diffusion model was used for modelling the process of preg-robbing, which has not been modelled before using experimental data. A simple film diffusion model was also used to model the adsorption of aurocyanide onto activated carbon. The model developed was then applied to a number of oxide and sulphide ores. found that the leaching model satisfactorily described the extraction of gold from the ore. It was also found that plant activated carbon should be used for the adsorption model calibration. When the model was used to simulate the behaviour of different ores, it was found that the recovery of gold was most closely linked to the flowrate of slurry through the circuit. For refractory ores, the most important consideration was the relative kinetics of the processes of leaching, adsorption onto activated carbon and preg-robbing at the ore surface. When preg-robbing was slower than adsorption, the circuit gold extraction could be improved by removing the leaching tanks, so that the preg-robbing must compete with the faster adsorption onto activated carbon. Neither the carbon distribution nor the mechanism of carbon transfer was found to have a significant effect on the extent of preg-robbing.