Rate Phenomena in the Oxidation of Zinc, Iron and Copper Sulfide Pellets

Abstract

The initial rates of oxidation of zinc, iron and copper sulfide pellets in an air stream were studied under well-defined conditions of flow and temperature. Simultaneous measurements were made of pellet temperature and of the rate of sulfur dioxide evolution. The effect of temperature on the initial reaction was determined and the corresponding activation energies were calculated. The oxidation of zinc and copper sulfides proceeds topochemically. The rate controlling mechanism changes from chemical reaction to mass transfer as the initial pellet temperature increases. At temperatures about 924 K, the reaction mechanism of ferrous sulfide changes from oxidation of the sulfide to oxidation of diffusing iron at the surface.