Dissolution Kinetics of Complex Sulfides Using Acidophilic Microorganisms

Abstract

Bioleaching studies were conducted to evaluate a complex sulfide concentrate using an acidophilic microorganism. The leaching kinetics were found to vary based on pulp density, Fe and pH. In addition, the leaching efficiency increased as the Fe(II) concentration increased up to 20 kg.m(-3), after which it decreased due to an increase in iron precipitation. Furthermore, the bacterial activity was good based on observation of the iron oxidation rate and pH and Eh studies. The leaching efficiencies decreased below 2 and 5% (w/v) in the pH and pulp density studies, respectively. Furthermore, the XRD analyses revealed the presence of various product layers, while the SEM-EDX analyses showed partial contact between different sulfide minerals that resulted in formation of a galvanic couple. The dissolution rate followed a product diffusion model. The diffusivity of Fe(III) for chalcopyrite and sphalerite were calculated. [doi:10.2320/matertrans.M2009195]