Statistical analysis of bioleaching copper, cobalt and nickel from polymetalic concentrate originating from Kamoya deposit in the Democratic Republic of Congo

摘要

Statistical design and analysis of experiments have been used to study the influence of selected technological factors on the bioleaching of polymetallic concentrate originating from the Katanga province in the Democratic Republic of Congo. A L_(25) orthogonal array has been chosen to analyze the direct effect of temperature, initial pH, leaching duration, stirring speed and pulp density on the degree of copper, cobalt and nickel yield in solution. The optimal values for each variable have been determined using Taguchi method through signal-to-noise ratio analysis. ANOVA has been used further to outline the individual contribution of each parameter and to evaluate their possible interactions. It has been found out, that pulp density has the most pronounced influence on the bioleaching yield of the three studied metals altogether, followed by pH and temperature. For the bioleaching of copper alone, the following optimal values have been determined: temperature 37.5 °C; pH 1.6; leaching duration - 20 days, stirring speed - 350 rpm and pulp density - 7.5 %. These optimal conditions have been re-confirmed by verification tests which have brought copper bioleaching yield close to 73 percent.