Effect of Mass Transfer and Bulk Flow on the Zinc Oxide Reduction by Methane

Abstract

Zinc oxide reduction with methane can introduce a new zinc-producing technology. The advantages of this method with respect to conventional carbothermic furnaces are lower operating temperatures, a simple indirect condenser, and copreparation of synthesis gas. The kinetics of ZnO reduction by CH4 at the chemical control regime has been studied on the thermogravimetric (TG) scale and at moderate temperatures extensively (Ale Ebrahim, H.; Jamshidi, E. Trans. Inst. Chem. Eng. 2001, 79A, 62−70). On the industrial scale with large ZnO pellets, mass transfer and bulk flow will be effective even at moderate temperatures. Therefore, a successful mathematical model for the design of such industrial plants is needed. In this work the ZnO + CH4 reaction at high temperature (1000 °C) was studied, where the kinetic resistance decreased considerably. Thus, the effect of mass transfer and bulk flow can be considered in on the TG scale. Then a mixed control model was developed which contains the effects of external mass ...