Development of a Kinetic Model of the Bacterial Dissolution of Copper Concentrate

The present study introduces a new approach to understand the copper dissolution rate and to find an adapted mathematical statement for particle shrinkage rate in a batch bioleaching system. Four size classes of a chalcopyrite concentrate, namely [D1 : (−54 + 44)μm, D2 : (−44 + 38)μm, D3 : (−38 + 25)μm and D4 : (−25)μm], were used in the batch bioleaching tests by applying a mixed culture of moderately thermophilic microorganisms. The pulp density and temperature were 8 (%w/v) and 50 °C, respectively. Findings delineated that the bioleaching time can be divided into two specific time intervals: first, the surface reactions were the prevailing controlling step; second, the prevailing mechanism was diffusion through the product layer, whereas the overall rate of the process may be related to both through a Q factor using a mixed model. A mathematical model was developed based on particle size distribution (PSD) and a kinetic model. Experimental validation of the mixed model was accomplished by the representative sample with d80 = 54 microns. Results showed that the PSD of the specific sample was in good agreement with Rosin–Rammler function. Besides, the simulation result of the conversion fraction had the best conformity with the experimental data (with a maximum error of approximately 7%). This paper should be considered as an initial part of a larger, global model for chalcopyrite concentrate bioleaching.