Bioleaching of chalcopyrite concentrate by acidophilic thermophile Acidianus brierleyi

The kinetics of bioleaching of a chalcopyrite concentrate by the thermophil ic archaea Acidianus brierleyi was studied in batch and continuous-flow sti rred tank reactors. In the batch reactor, the thermophile A. brierleyi solu bilized chalcopyrite much faster at 65 degrees C than did the mesophile, Th iobacillus 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 insignif icant. Batch rate data collected under a variety of operating variables wer e analyzed to estimate kinetic and stoichiometric parameters for the growth of A. brierleyi on chalcopyrite. The batch model and the estimated paramet er values were used to find optimum levels of initial cell concentration an d initial mineral-liquid loading ratio. Simulations based on continuous rea ctor model and the parameter values were used to predict the leaching fract ion as a function the number of reactors connected in series.