Kinetics of oxychlorination of chromite: Part II. Effect of reactive gases

The effects of Cl2/O2 ratio, P(Cl2+O2), PCl2, and PO2 on the oxychlorination rate of the chromite mineral were determined between 750 and 1000°C using isothermal TGA measurements. The effect of the gases’ composition on the oxychlorination rate of chromite were compared with those resulting from the oxychlorination of simple oxides of the chromite (Cr2O3, Fe2O3 and MgO). The apparent reaction orders with respect to Cl2+O2, Cl2, and O2 for the chromite oxychlorination at 750°C were about 0.94, 1.24, and −0.30, respectively. At 1000°C, apparent reaction orders with respect to the reactive gases changed significantly as the reaction progressed. Boat experiments were carried out to oxychlorinate a chromite concentrate between 600 and 1000°C. The reaction products were analyzed by SEM, XRD and chemical analysis. The oxychlorination of a chromite concentrate at about 800°C led to the partial elimination of iron increasing the Cr/Fe ratio in the treated concentrate. A part of chromium was also oxychlorinated and it was recovered as chromium oxychloride (CrO2Cl2).