EVALUATION OF GALVANIC INTERACTION BETWEEN SPHALERITE AND MANGANESE DIOXIDE THROUGH LEACHING AND POLARIZATION STUDIES

摘要

Dissolution of sphalerite and manganese dioxide minerals in the presence of one another in sulphuric acid medium was studied using compact disc electrodes of the minerals under various H_2SO_4 concentrations (0.01-0.5M) and temperatures (25-60 deg C). Both (H~+) and temperature had a positive effect on the reaction rate. Strong galvanic interaction was observed to take place between sphalerite and manganese dioxide, the galvanic interaction predominating over the individual dissolution (self-corrosion) rates. Evans diagrams constructed from polarization curves of the two minerals were helpful in interpreting the leaching data. The electrochemical nature of the dissolution reaction was analysed through the application of the Butler-Volmer equation and was confirmed from polarization measurements conducted with the respective mineral electrodes.