Copper recovery from tailings through bioleaching and further application of bioleached tailings residue: Comprehensive utilization of tailings

Severe environmental pollution and resources waste were caused by tailings. For the sake of making comprehensive utilization of tailings, tailings bioleaching for copper recovery and further application of bioleached tailings residue to make cemented tailing backfill materials were investigated. Such study clarified the potential possibility of bioleached tailings residue in cleaner production and economic benefits, which should contribute to a good reference for comprehensive utilization of tailings. Results showed that adding tailings and bacteria at appropriate interval during tailings bioleaching, particularly adding bacteria both at initial inoculation and day 10, can improve copper recovery (5.46%) and bacteria concentration (7.39 × 107 cells·mL−1). Better performances with high compressive strength (3.82 MPa) and low water-holding capacity of cemented tailings backfill (CTB) specimens using bioleached tailings residue was obtained. 16S rDNA analysis illustrated that bacteria community structure was differentiated significantly during bioleaching experiment. Leptospirillum ferriphium accounted for the highest proportion of bacteria community structure throughout bioleaching process among all the samples. Furthermore, possible reaction mechanism was put forward suggesting the possible role of precipitation including KFe3(SO4)2(OH)6 and (KH3O)Fe3(SO4)2(OH)6 formed by Fe3+ hydrolysis can contribute to performance of CTB specimens. Moreover, adding tailings and bacteria at appropriate interval was beneficial to removal of excessive hazardous ions, such as Fe3+ and SO42− from bioleaching solution.