Investigation into the kinetic regularities of impurity transfer during the sulfuric acid leaching of the zinc-containing middlings of two-stage Waelz process of zinc cakes: Part II. regularities of sulfuric acid leaching the industrial samples of calcined Waelz oxide of zinc production

Abstract

Kinetic regularities of leaching the actual industrial sample of calcined Waelz oxide of zinc production are determined. The basic reaction mechanism is established. The dissolution of solid-phase particles can be conditionally differentiated into two stages. In the initial instant, the reaction is developed in the external diffusion mode following the topochemical mechanism. The process mechanism changes at the second leaching stage, which is evidenced by the limiting character of the time dependence of recovery of zinc, which is caused by the formation of dissolving parts of reaction products forming the poorly permeable films on the surface. The internal diffusion is the limiting stage in this case.