Optimization of copper bioleaching of low grade Cu-Sulfide ore using response surface methodology

Recovery of copper from low grade Cu-sulfide ore from Meyduk mine of Shahrbabak Copper Complex was evaluated by means of microbial leaching. Bioleaching was performed using Mesophelic bacteria A. Ferrooxidans (T.f) and A. Thiooxidans (T.t). 2-factoriel methodology used to find the influential parameters among pulp densities, inoculum, T.t bacteria percentage, pH, amount of Ferrous and amount of Sulfur. By means of this method, pulp densities, T.t bacteria percentage and amount of Ferrous were known as the most important parameters in the bioleaching process. Response Surface Methodology was applied to optimize the recovery of copper. Experiments were conducted based on a rotatable Central Composite Design and analyzed using response surface methodology. The bioleaching process was investigated as a function of three independent factors solid to liquid ratio (5-10 w/v), T.t bacteria percentage (70-80%) and Initial concentration of ferrous ions (20-30g/l). The optimum conditions for the copper recovery were found to be respectively 7.5w/v, 80% and 20 g/l, for solid to liquid ratio, T.t bacteria percentage and Initial concentration of ferrous ions. Under these conditions, maximum bioleaching capacity of the medium for copper recovery was determined to be 99.4%.