Carbothermal reduction of zinc ferrite

Abstract

The carbothermal reduction of zinc ferrite was studied using X-ray diffractometer (XRD), wet chemical analysis, scanning electron microscope (SEM), surface area meter, and thermogravimetrical analysis (TGA) systems. Zinc ferrite was found to be decomposed to ZnO and Fe2O3 initially and carbothermal reduction of ZnO and Fe2O3 took place simultaneously. The results of the surface area measurement indicated that the surface area of the solid sample increased with reaction time. Pore volume and average pore diameter were found to increase, reach a maximum, and then decrease with reaction time. These results were explained by considering the escape of zinc vapor, the expansion of the iron oxide grain, and the sintering of the iron. A mechanism and a model were proposed to explain the reaction. The experimental results of the thermogravimetrical analysis indicated that the reaction rate can be increased by increasing either the argon flow rate or the reaction temperature. Furthermore, the reaction rate was found to increase with a decrease in either the sample height, the molar ratio of ZnFe2O4/C, the size of the carbon agglomerate, or the initial bulk density.