Particle size, pH and Fe(III) ions affect the process of bioleaching of copper from chalcopyrite ores. In the study presented herein a copper sulfide ore was subjected to bioleaching process using a mixed microbial consortium obtained from a biotrickling filter treating high loads of H2S at different mineral particle size, distinct medium pH and various additional Fe(III) ion concentrations as leaching agent. After 1300h of operation, the total copper recovery achieved a value of 50% in the most acidic conditions. A decrease of 2.5 units of pH implied an increase in the efficiency of 35%. It was also observed an optimal particle size (between 2 and 3 mm), considerably higher than previous reported studies, meaning a decrease in operational cost to mill material. Finally, results indicate that there is a threshold concentration of ferric ion from which the system is not sensitive (500 ppm). (C) 2012 Elsevier Ltd. All rights reserved.