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.