A phenomenological model of the bioleaching of complex sulfide ores

The leaching kinetics of a complex copper sulfide ore has been studied in laboratory-scale airlift percolators. Experiments were carried out to study the effect of a pure strain of Thiobacillus ferrooxidans on the dissolution rate of the different copper sulfide species contained in the ore. Comparison with the dissolution rate observed under sterile ferric ion solution conditions indicated that the catalytic role of bacteria was mainly related to the oxidation of ferrous to ferric ions in the leaching solution by bacteria, both adsorbed on the surface of the mineral particles and free in the leachingssolution. A phenomenological model was developed to account for the kinetics of the leaching process of complex ores in the percolator experiments. The model reproduces well the evolution in time of measured copper recovery, total iron concentration and bacteria in solution. A sensitivity study of the model parameters was performed to extend the results to the simulation of the overall kinetics of the process.