In:
Huydrometallurgy
Accepted for publication

Authors:
Ali Ahmadi
Department of Mining Engineering, Isfahan University of Technology, Isfahan, Iran, a.ahmadi@cc.iut.ac.ir; Tel: +98 311 3915113; Fax: +98 3912776.
Mohammad Ranjbar
Department of Mining Engineering, Shahid Bahonar University, Kerman, Iran
Mahin Schaffie
Department of Chemical Engineering, Shahid Bahonar University, Kerman, Iran
Jochen Petersen
Centre for Bioprocess Engineering Research, University of Cape Town, South Africa

Abstract
In this paper a model of conventional and electrochemical bioleaching of high grade complex copper sulfide ores or flotation concentrates in isothermal stirred tank reactors is presented and compared to experimental data. Experiments were conducted in an electro-bioreactor using a mixed culture of moderate thermophile microorganisms at pulp density 20% (w/v), leaching time 10 days, stirring rate 600 rpm and temperature 50 °C. The behavior of conventional and electrochemical bioleaching processes was described with a combined reaction-based kinetic model. The model considers the effects of mineralogical composition of the feed, the properties of the initial solution, the presence of iron- and sulfur oxidizing microorganisms and both the passivation and electro-reduction of chalcopyrite on the values of copper recovery, pH and redox potential during the processes. Comparing the values obtained from the integrated semi-empirical model with the experimental data showed that the model results are in good agreement with the real leaching data of copper recovery, ORP (ox¬¬¬¬idation reduction potential) and pH for the mentioned processes under different experimental conditions.