Selection of thermophiles for base metal sulfide concentrate leaching, Part I: Effect of temperature on copper concentrate leaching and silver recovery

• Published in: Minerals engineering Vol. 106; pp. 7 - 12
• Main Authors: Norris, Paul R., Laigle, Ludovic, Ogden, Thomas J., Gould, Oliver J.P.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.05.2017
• Subjects: Bioleaching; Copper concentrates; Silver recovery; Thermophiles; Bioleaching; Copper concentrates; Silver recovery; Thermophiles
• ISSN: 0892-6875; 1872-9444
• DOI: 10.1016/j.mineng.2016.12.003

•Copper-silver concentrate bioleaching was observed at 30, 48 and 76°C.•S. thermosulfidooxidans displaced Acidithiomicrobium during leaching at 48°C.•Bioleaching temperature influenced hydrometallurgical, post-leach silver extraction.•Thiosulfate was most effective Ag extractant with high temperature bioleach residue. The influence of temperature on bioleaching of a copper-silver concentrate of a black shale-ore was observed at 30, 48 and 76°C. Post-leach residues’ weights and copper contents decreased with increase in leaching temperature while the iron contents increased through more iron precipitation. A designed, incremental increase in the concentration of copper in solution resulted in Sulfobacillus thermosulfidooxidans replacing a species of Acidithiomicrobium as the dominant iron-and mineral sulfide-oxidizing strain in the mixed culture used at 48°C. The temperature of bioleaching influenced the hydrometallurgical extraction of silver from post-leach residues. Thiosulfate was most effective with a high temperature bioleach residue while ferric chloride and copper/ammonium/thiosulfate was most effective with a low temperature bioleach residue.