Effect of preoxidation on the reduction of ilmenite concentrate powder by hydrogen

In this study, hydrogen reduction of raw and preoxidized ilmenite concentrates powder, with particle size less than 74 mu m, is investigated using a thermal analyzer at 1123, 1173, and 1223 K in a 30% H-2 + 70% Ar atmosphere. The reduction rate by hydrogen was found to be accelerated due to preoxidation treatment of the raw ilmenite concentrate. The reduction of both raw and preoxidized ilmenite concentrates can be divided into two stages: Fe3+ -> Fe2+ and Fe2+ -> Fe. The Fe3O4 -> FeO stage overlaps with the Fe2O3 -> Fe3O4 stage during reduction process of the preoxidized ilmenite concentrate. Moreover, the preoxidation treatment can effectively decrease the reduction activation energy. The scanning electron microscopy (SEM) and the X-ray powder diffraction (XRD) techniques were used to characterize the micromorphology and phase of the products. The promotion mechanism of reduction of ilmenite by hydrogen through preoxidation treatments is also discussed. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.