Kinetics and mechanism of MnO2 dissolution in H2SO4 in the presence of pyrite

This paper describes a study of the kinetics and mechanism of MnO2 dissolut ion in H2SO4 in the presence of pyrite through leaching and electrochemical parameters. Manganese(IV) was found to dissolve mainly through reduction b y the ferrous ion generated during oxidation of pyrite by the ferric ion. T he oxidation which is slower and rate controlling may proceed through two d ifferent reactions, one producing SO and the other SO42-. Manganese dissolu tion runs at the same rate as that of pyrite oxidation by maintaining ferro us ion concentration at a much lower level than that of ferric. Kinetic equ ations based on corrosion coupling principles are developed to explain the observed leaching behaviour.