Optimization of Bacterial Oxidation Process Parameters for Selective Leaching of Nickel by Thiobacillus Ferrooxidans

Abstract

Nickel bioleaching from copper flotation concentrate assumes greater significance because of its value and not many studies are carried out in these lines. Hence, nickel leaching was attempted and several process parameters of bacterial oxidation for copper flotation concentrate were examined for optimization. The parameters considered for shake flask leaching experiments were temperature, pulp density, particle size, agitation, residence time and inoculum size. The effect of variable proportions of each parameter on nickel leachability was studied. Optimum values of pulp density (10%) and agitation (140 rpm) played an important role in controlling the mass transfer resistance during leaching process. Increase in temperature from 27oC to 30oC has accelerated the bacterial oxidation process while initial concentration of inoculum (1-10%) has not shown considerable variation in nickel leachability. A particle size of ±60#size was found to be essential for bacterial attack. Maintenance of optimum conditions of leaching has yielded considerable nickel recovery (55%) compared to low recovery under unoptimal conditions.