GALENA AND SPHALERITE DISSOLUTION PROCESS IN ACIDIC CHLORIDE MEDIA

摘要

An electrochemical study has been carried out on sphalerite and galena in solutions of pH 2 containing different chloride concentrations solutions using carbon paste electrodes and cyclic voltammetry. The analysis of the voltammetric results for galena indicates that an increase in chloride concentration improves the galena dissolution and diminishes the energy requirements. However, the increase should be controlled to avoid the concentration region where the galena surface is passivated with PbCl_2(s). The oxidation of sphalerite occurs in two stages, depending on imposed potential. At low potentials, the oxidation products are Zn(II) and elemental sulfur; at high potential thiosulfate is formed, but under interface conditions it is unstable and is quickly oxidized to sulfate. The influence of change in chloride concentration depends on the oxidation zone. In the first stage, increase of chloride concentration augments the oxidation rate, while when thiosulfate is formed the oxidation rate diminishes.