Effect of thermal pretreatment on recovery of nickel and cobalt from Sukinda lateritic nickel ore using microorganisms

Experimental investigation made previously oil microbiological leaching of nickel and cobalt from the laterite nickel ore of Sukinda Valley reveals that the recovery was not very much promising under any favorable conditions. Therefore, in order to improve the efficiency for bioleaching, the homogenized lateritic ore in palletized form is thermally pretreated by roasting at different temperatures. The parameters studied for the bioleaching experiments were the four types of pretreated ore which were roasted at different temperatures, i.e., 300 degrees C, 400 degrees C, 600 degrees C and 800 degrees C, in shake flask by using a mixed mesophilic acidophilic bacterial consortium consisting predominantly of the Acidithiobacillusferrooxidans strain. It was observed that the pretreated ore at 600 degrees C with 10% (w/v) pulp density showed maximum recovery of nickel and cobalt, i.e., 59.18% (4.556 ppm) and 65.09% (0.546 ppm), using 10% (v/v) (2.5 x 10(8) cells/ml) consortium concentration at 1.5 pH, 30 degrees C, and 150 rpm after an incubation period of 31 days.