Reduction mechanisms and behaviour of zinc ferrite - Part 1: pure ZnFe2O4

The reduction of dense zinc ferrite (ZnFe2O4) in CO-CO2 and CO-N-2 gas mixt ures has been investigated at temperatures between 800 and 1100 degreesC. T he rate measurements obtained in these studies were complemented by microst ructural characterization of the reacted and partially reduced samples. The reduction kinetics of ZnFe2O4 were found to be directly related to the mor phology of the reaction product; iron, wustite and magnetite phases were ob served. The various microstructural features of the reaction interfaces and product morphologies were explained in terms of the relative rates of the gas-solid reactions and the mass-transport processes. Changes in growth mec hanisms and reduction kinetics that occur with changing reduction condition s are discussed along with the mechanisms of formation of various types of product microstructures.