Kinetics of chalcopyrite dissolution by hydrogen peroxide in sulphuric acid

The extraction of copper from a chalcopyrite concentrate by hydrogen peroxide in sulphuric acid solutions was studied. The influence of various parameters was investigated in order to elucidate the kinetics of chalcopyrite dissolution. It was determined that stirring speed had no effect on the rate of chalcopyrite dissolution, which suggested that reaction was not controlled by liquid-phase diffusion. Dissolution curves were found to conform to the surface reaction controlled shrinking core model, i.e., 1−(1−X)1/3=kst. Both the magnitude of the activation energy of 60 kJ/mol and the linear relationship between the rate constant and the inverse particle radius support the fact that dissolution is controlled by the surface reaction. Hydrogen peroxide had great influence on the rate of chalcopyrite dissolution; a reaction order of unity was calculated with respect to the concentration of this oxidant. Sulphuric acid also had influence on chalcopyrite dissolution, with a reaction order of 0.3 with respect to the acid concentration being established.