KINETICS OF THE PRECIPITATION OF MANGANESE AND COBALT SULFIDES IN THE PURIFICATION OF A MANGANESE SULFATE ELECTROLYTE

Manganese and cobalt sulphides are precipitated from a sulphate solution in a batch reactor by the addition of ammonium sulphide. Experimental evidence is produced to show that first-order kinetics simulate the precipitation of manganese sulphide. The bulk of the solids formed have a chemical composition which may be represented by either MnS.H2O or MnOH.SH. The precipitation of cobalt sulphide shows three kinetic regions; an induction period in which little change in solution concentration is observed, followed by rapid precipitation and finally a very slow approach to equilibrium. Seeding of the reactor with particles from a previous run eliminated the induction period completely.