Chemism and kinetics of the oxidation of zinc-calcium oxysulfide

Abstract

The sequence of phase transformations and the kinetics of the solid-phase (heating to 1273 K) oxidation of zinc-calcium oxysulfide CaZnSO with air are determined by thermodynamic, thermogravimetric, mass spectrometric, and X-ray diffraction analyses. The oxidation process is shown to be accompanied by the formation of the CaSO4 and ZnO phases depending on the heating conditions, as well as by the formation of CaO with SO2 evolution. The two-stage oxidation of CaZnSO is interpreted by the Avrami-Erofeev kinetic equations with activation energies of 190 and 422 kJ/mol.