Kinetics of Roasting Reaction Between Synthetic Scheelite and Magnesium Chloride

Abstract

Conversion of CaWO4 to MgWO4 by roasting scheelite with MgCl2 is the key step for the subsequent alkaline extraction of tungsten from scheelite. In this study, the factors influencing the conversion efficiency of MgWO4 during the roasting of synthetic scheelite and MgCl2 were evaluated, and the reaction kinetics were explored by model fitting. The results indicate that the conversion efficiency increases with an increase in roasting temperature and magnesium chloride dosage, and that a decrease in mineral particle size also increases the conversion efficiency. Moreover, the roasting reaction between synthetic scheelite and MgCl2 at 773–923 K fits well to the Avrami–Erofeev kinetic model, and the roasting reaction is controlled by both diffusion and chemical reaction. This study contributes to a better understanding of the roasting process of scheelite with MgCl2 and the development of a new route for extracting tungsten from scheelite.