STUDIES ON INITIAL DISSOLUTION KINETICS FROM POLARIZATION DATA .1. GALENA IN FERRIC-CHLORIDE

Abstract

Electrochemical aspects of galena dissolution in ferric chloride media have been examined through concurrent polarization studies of the individual half cell reactions. The mixed potential and the mixed currents obtained from the intersections of such curves at different solution conditions have been analysed to understand the kinetics. It has been observed that the anodic half reaction traverses through activation as well as diffusion controlled domains both of which are encompassed by cathodic ferric reduction depending an the ferric concentration. This aspect has a very critical bearing in the process. Other solution conditions like ferrous ion, sodium chloride concentration and temperature also have pronounced effects on the process. It has been envisaged that varying solution conditions can change the process from anodic control to cathodic control and from activation control to diffusion control, This may provide the explanation for different observations in the literature regarding linear and diffusion controlled kinetics.