Influence of SiO2 on the gas-based direct reduction behavior of Hongge vanadium titanomagnetite pellet by hydrogen-rich gases

In this study, the influence and mechanism of SiO2 on the gas-based direct reduction behavior of Hongge vanadiumtitanomagnetite pellet (HVTMP) by hydrogen-rich gases was investigated. Increasing SiO2 during the initial stage caused the reduction degree of HVTMP to initially increase and then decrease. At the later stage, SiO2 retarded the reduction, and this effect increased upon increasing the SiO2 addition. SiO2 caused the decrease of the metallization degree by forming hardly reducible Fe2SiO4 and hindering the further reduction of Fe2TiO4 to Fe. The size of metallic iron grains diminished gradually, and the boundary between the metallic iron phase and the slag phase became less obvious with the increase of SiO2 addition. Additionally, the number of metallic iron whiskers decreased, and the growth of metallic iron whiskers transformed from dispersed to close clusters, which decreased the reduction swelling. This study provides a theoretical and technical basis for the smelting of Hongge vanadium titanomagnetite in shaft furnaces by hydrogen-rich gases. (C) 2021 Published by Elsevier B.V.