Kinetics improvement of high-grade bioleaching by effects separation sulphides

The kinetics of bioleaching of sulphide concentrates by Thiobacillus ferrooxidans can be improved by performing separately the two operations related to the indirect contact mechanism, namely chemical leaching and biological oxidation of the Fe2+ produced in the chemical stage (IBES: Indirect Bioleaching with Effects Separation). This approach allows for the individual enhancement of each stage, with the chemical attack of ferric iron on sulphides conducted at higher temperatures, while the biological oxidation stage is more effective when applying biofilm models. Moreover, this process reduces inhibitory phenomena caused by bacterial damage due to solid particle abrasion. The 1BES process has been tested on a Spanish copper-zinc and copper sulphide concentrate with the goal of selectively dissolving zinc for recovery via solvent extraction, leaving behind a copper concentrate suitable for pyrometallurgical treatment. Key attributes of this process, including moderate temperature, atmospheric pressure, cost-effectiveness of the leaching agent, and operational flexibility, make it economically attractive. A semi-industrial pilot plant is currently being established to validate these findings.