Modeling of biooxidation of gold bearing pyrite-arsenopyrite concentrates by Thiobacillus ferrooxidans

摘要

The Hutti Gold Mines Company Ltd., (HGML) Karnataka, India is the largest producer of gold in India. Recent explorations have revealed the presence of large quantities of sulphidic refractory gold ores in which gold is associated in pyrite/ arsenopyrite matrix. We have undertaken a systematic program of design and operation of demonstration scale bioreactor set-up in order to establish the feasibility of biooxidation technology for pretreatment of flotation concentrates produced from such refractory gold ores. In this paper, we report the results of modeling of biooxidation of mixed sulphidic concentrates by Acidothiobacillus ferrooxidans. A comprehensive systems approach is employed for modeling of complex biooxidation process by (a) decomposition of the complete system into several subsystems, (b) modeling individual systems, and (c) finally integrating the subsystems model into final system model. The model for subsystems is developed by writing the mass balance equations for various species involved. The kinetic parameters of the model are determined by designing the experiments in such a manner that only one subsystem is operational. After experimental verification, the models of the subsystems are combined to yield a complete biooxidation model. This model is tested in both laboratory scale batch and continuous biooxidation processes. The model predictions are found to agree with the experimental data reasonably well. A further analysis of the model is carried out to predict the conditions for efficient biooxidation. It is expected that such a model will assist the scale up of the process from laboratory scale to demonstration bioreactor.