Study on comprehensive utilization of tailings by using bioleaching and microbial-cementation

This study aims to realize copper recovery from tailings and make further application of bioleached tailings residues as microbial-cemented tailings backfilling materials (MCTB). Results show that copper contained in tailings can be recovered by bioleaching. Behaviors of microbial-cemented tailings backfilling materials made from bioleached tailings residues are evaluated. Better performances with high compressive strength, small water-holding capacity and shrinkage ratio are obtained through using bioleached tailings residues. A mercury injection test is conducted, which reveals the effect of bioleached tailings residues on microstructure evolution in microbial-cemented tailings backfilling materials. Small pore volume along with uniform pore distribution and small specific surface area is obtained after using bioleached tailings. Simultaneously, concentrations of hazardous ions including Zn2+, Pb2+, As3+, Cd2+ and Hg2+, can be reduced during spraying experiment by using bioleached tailings residues. Effect of bacterial species, especially Acidithiobacillus ferrooxidans, Leptospirillum ferriphilum, Acidibacillus ferrooxidans and Escherichia coli, on reducing hazardous ions concentration is analyzed. Possible reasons suggesting the role of bioleached tailings residues contributing to low concentration of hazardous ions and good performances of microbial-cemented tailings backfilling materials are put forward.