Possibilities for Co(III) dissolution from oxide ore through simultaneous bioleaching of pyrite

摘要

Solubilisation of cobalt (III) from a copper cobaltiferous oxide ore has been realized through ferrous iron reductive leaching, the ferrous iron itself being generated from pyrite mixed with the ore. A bacterial consortium involving three different acidophilic chemolithotrophs was adopted for the pyrite bioleaching thus facilitating iron supply in the system. The concentration of ferrous iron has been found to be key factor for cobalt(III) solubilisation. Even very small amount of pyrite addition to the ore has contributed to leaching of nearly 95 % of the trivalent cobalt within less than 3 days. It was found out that Co(III) dissolution was quite efficient and that bacterial presence was beneficial in view maintaining the Fe~(2+)/Fe~(3+) cycling. When the added pyrite was bioleached the simultaneous cobalt leaching has required less than the stoichiometric amount of ferrous iron as reducing agent. Moreover leaching has been maintained at elevated Eh levels thus implying lower operational costs due to less reagent consumption.