Effect of Specific Surface Area of a Mechanically Activated Chalcopyrite on Its Rate of Leaching in Sulfuric Acid-Ferric Sulfate Media

The aim of the current study has been to investigate the influence of mechanical activation through intensive milling of a chalcopyrite mineral sample on its BET surface area and the subsequent effect on its leaching reaction rate and mechanism. Leaching kinetics mechanisms of the raw and mechanically activated chalcopyrite in the sulfuric acid-ferric sulfate media have been investigated. Rate-controlling step seems to be the diffusion through the protective product layer, and mechanical activation apparently has no significant effect on the leaching mechanism. An attempt has been made to describe the apparent rate constant as a function of BET specific surface area (S), specific surface energy (σ), and leaching temperature (T). An equation in the form of k = AS ² exp(σ∆S/RT) has been developed (A is a constant) and fitted to the experimental data with a fairly good agreement.