Bioleaching of chalcopyrite concentrate by acidophilic thermophile Acidianus brierleyi

The kinetics of bioleaching of a chalcopyrite concentrate by the thermophilic archaea Acidianus brierleyi was studied in batch and continuous-flow stirred tank reactors. In the batch reactor, the thermophile A. brierleyi solubilized chalcopyrite much faster at 65 degrees C than did the mesophile, Thiobacillus ferrooxidans at 30 degrees C. The chalcopyrite leaching with A. brierleyi was found to take place with a direct attack by adsorbed cells on the mineral surface, the chemical leaching with ferric iron being insignificant. Batch rate data collected under a variety of operating variables were analyzed to estimate kinetic and stoichiometric parameters for the growth of A. brierleyi on chalcopyrite. The batch model and the estimated parameter values were used to find optimum levels of initial cell concentration and initial mineral-liquid loading ratio. Simulations based on continuous reactor model and the parameter values were used to predict the leaching fraction as a function the number of reactors connected in series.