Selective removal of cobalt and copper from Fe (III)-enriched high-pressure acid leach residue using the hybrid bioleaching technique

[Display omitted] •Hybrid bioleaching strategy was developed for metals removal from HPAL residue.•Hybrid bioleaching significantly enhanced metals release during bioleaching process.•Moderate thermophile with sulfur oxidizer and iron oxidizer was more efficient.•The addition of Fe(II), S0 and citric acid improved bioleaching environment.•Conditions for Co and Cu removal from HPAL residue were established. Removal of metals from high pressure acid leaching (HPAL) residue was essential to alleviate potential environmental threat and avoid valuable metals loss. However, cost-effective metals extraction from HPAL residue remains a difficulty. In this study, a hybrid bioleaching process was developed for Co and Cu extraction from HPAL residue of Cu-Co sulfide ores. Results for microbial community structure optimization showed that moderate thermophilum consortium with coexistence of iron oxidizer and sulfur oxidizer was more efficient on metal extraction compared with mesophiles. Further addition of citric acid, Fe (II) and S0 significantly enhanced the release of metals through improving the total biomass, attached cells and community diversity. As a result, 87.91% of cobalt and 58.52% of copper were extracted at initial pH 1.4 and pulp density of 50 g/L by hybrid bioleaching. The hazardous potential assessments revealed that the bioleached residue could be disposed safely. These findings demonstrated that organic acids assisting bioleaching with community adjusting was a promising strategy for metals removal from HPAL residue.