Catalytic effects of activated carbon and surfactants on bioleaching of cobalt ore

• Effect of activated carbon and surfactants on carrollite bioleaching was tested.
• Both of the two kinds of additives can enhance carrollite bioleaching remarkably.
• Synergistic effects of combined catalysts were observed.
• Adding combined catalysts, cobalt leaching rate raised over 22% and time reduced 30%.

The effects of activated carbon and/or surfactants on the bioleaching behavior of cobalt ore have been investigated in this paper. It was demonstrated that activated carbon and surfactants (Tween-20 and Tween-80) can significantly promote the dissolution rate of carrollite, either individually or in combination when coupled with ZY101 bacteria strain. The cobalt leaching efficiency increased from 71.3% to 90.8% when 1.0 g/L activated carbon was added, and such an improvement was ascribed to the galvanic interaction between activated carbon and carrollite. In addition, the leaching efficiency of cobalt increased from 71.3% to 92.4% by 0.1 g/L Tween-20 or to 93.2% by 0.1 g/L Tween-80, by changing the surface condition of the mineral and accelerating the bio-oxidation of formed elemental sulfur. When both activated carbon and surfactant were added, the leaching efficiency of cobalt increased by more than 22%, and meanwhile the leaching time decreased by more than 30%. It is shown that the catalytic effect of the combined catalyst was much more significant than that when only using a single catalyst. A similar trend was observed in the case of elemental copper extraction during the bioleaching process.