KINETIC STUDY OF OXIDATION OF PELLETED ZINC SULFIDE POWDER HAVING GRAIN SIZE DISTRIBUTION

Abstract

Oxidation of porous zinc sulfide pellets, composed of fine grains having log-normal size distributions, was carried out using a differential flow reactor under oxygen partial pressure of 1-16 kPa and temperature of 953-1113 K.
The overall conversion rate data were represented by a simple power law rate expression. The reaction order with respect to the solid reactant varied with the standard deviation of the grain size distribution. This variation agreed well with the theoretical prediction by the grain model accounting for grain size distribution. The reaction order with respect to the gaseous reactant was 1/2.
The surface rate constant was then found to be correlated in an Arrhenius equation. K''= 5.56×10⁸e^-244/RT (mol^1/2/m^1/2 • s) The rate constant agreed well with that for oxidation of sphalerite single crystals by other workers as well as with the rate constant reproduced from the data in the literature on oxidation of porous pelleted zinc sulfide.