Parametric optimization for leaching of cobalt from Sukinda ore of lateritic origin - A Taguchi approach

This paper describes the process of leaching of cobalt from an indigenous Sukinda lateritic ore under wide range of experimental variables. Taguchi method utilizing L-18 orthogonal array has been adopted to identify the influential process parameters responsible for higher degree of recovery with enhanced leaching of cobalt from Sukinda ore. The effect of process variables such as additive, temperature, sulfur di oxide gas, sulfuric acid, time, stirring speed, pulp density and particle size on effective leaching of cobalt was investigated. Analysis of variance indicated that the temperature was the most influential leaching parameter. The optimized conditions for effective cobalt leaching were; no additive, temperature = 90 °C, sulfur di oxide = 3.7 l, sulfuric acid = 40 kg/T, time = 5 h, stirring speed 800 rpm, pulp density = 15% and particle size - 0.074 mm. Optimum conditions predicted by Taguchi method successfully enhanced the cobalt leaching efficiency to 85% suitable for further operation related to making it feasible at plant scale. The leaching of cobalt under optimized conditions was selective with respect to other metal ions the values being (% leaching) Cr: 0.022, Al: 0.1%, Mg: 0.5%, Fe: 0.15% and Ni: 2%. The mechanism of leaching process in the presence of sulfur di oxide combined and sulfuric acid has also been explained in the light of results obtained.