Migration Behavior of the MgO and its Influence on the Reduction of Fe3O4–MgO Sinter

To investigate the migration behavior of MgO in oxidization-reduction of the vanadium titano-magnetite (VTM) ore and the influence of its content on the reduction, the solid solution was prepared by annealing MgO and Fe3O4 and its oxidized products were isothermally reduced under H2–N2 atmosphere. It was found that the sinter with high MgO content showed faster reduction rate due to the formation of pores and the increase of active sites caused by the diffusion of Mg2+ into Fe3O4. In contrast, the as-oxidized sinter with high MgO content showed the slowest reduction rate due to the formation of high content of (MgO)x·(FeO)1−x (x=0.239–0.77) in the reduction process. MgO migrated from the solid solution and combined with partial Fe2O3 to form MgFe2O4 in the oxidization stage. In the reduction stage, MgO migrated outward as the oxidized sinter was reduced to Fe3O4 and FeO, while migrated inwards in the stage of Fe formation. MgO content in per mole formed FeO decreased as the sinter was reduced to FeO, while increased in solid solution during the Fe generation stage.