Application of mixed potential theory in hydrometallurgy

The concept of mixed potentials has been applied to explain important aspects of corrosion for many years. In many hydrometallurgical systems, reactions occur by means of electrochemical mechanisms. Application of mixed potential theory to explain the kinetics of oxidative and reductive leaching processes is a useful concept in explaining observed results qualitatively. It explains the often observed rapid shift from one kinetic regime to another and provides basic information regarding sequential phase changes. Quantitative application of mixed potential theory requires a knowledge of individual electrode kinetics. From the individual electrode kinetics, mixed potentials and overall reaction kinetics may be calculated. Examples are presented for contact reduction, cyanidation and sulfide leaching.