Study on dechlorination kinetics from zinc oxide dust by clean metallurgy technology

Abstract

Cavity perturbation method was used to determine the dielectric properties (ε′, ε″, and tan δ) of zinc oxide dust. The process of dechlorination from zinc oxide dust by microwave roasting was evaluated considering the effect of different roasting temperatures and holding times. The research results showed that the ZnCl2 and PbCl2 with high-loss factor were heated preferentially by microwave, and the dechlorination rate can reach 97.22% after microwave roasting at 650°C for 40 min. The phases of zinc oxide dust before and after microwave roasting were observed and characterized by X-ray diffraction (XRD) analysis. The kinetics of dechlorination from zinc oxide dust was investigated. The three kinetic factors were obtained by the dynamic isothermal method, which provided a theoretical basis for dechlorination from zinc oxide dust. Thermodynamic analysis showed that the volatilization of chlorides was mainly ionic crystal phase transition process. The volatile kinetics of zinc oxide dust were controlled by the solid state diffusion and interface chemical reaction, during the microwave heating, with an activation energy E=46.6 KJ/mol and the reaction order n is level 1.