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 1300 h 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)

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