Surface characterization of arsenopyrite in acidic medium by triangular scan voltammetry on carbon paste electrodes

To optimize the industrial processes involving chemical or biological oxidation of arsenopyrite and to control acid rock drainage it is necessary to perform a precise characterization of the mineral surfaces. In this work we have demonstrated that a voltammetric study with carbon paste electrodes (CPE) provide a possible alternative method to allow a rough characterization of the arsenopyrite surface. By these means the presence of sulfur or FeAsO4 passive layers on the surface is shown, when arsenopyrite is previously oxidized by either chemical, biological and biological assisted methods. The presence of sulfur or FeAsO4 was confirmed by XRD and IRD surface determinations. On the other hand the heterogeneity of the precipitates formed during the previous oxidation process was detected by CPE-mineral voltammetry studies. These observations were confirmed by SEM photomicrographs of the surface treated arsenopyrite. (C) 1997 Elsevier Science B.V.