Modeling and optimizing process parameters, initial pH, pulp density, and initial concentration of ferrous ions by bacterial leaching to increase copper extraction from a low-grade ore of Sarcheshmeh Copper Complex was studied as an empirical model. Optimum conditions to achieve maximum total copper extraction were initial pH 2.0 and pulp density 1.59% without adding ferrous ions. In these conditions, model prediction for total copper extraction was 85.98%, higher than any value obtained in conducted experiments. (c) 2012 Elsevier Ltd. All rights reserved.