Effect of Al2O3 on the gas-based direct reduction behavior of Hongge vanadium titanomagnetite pellet under simulated shaft furnace atmosphere

Abstract

As a successive work to develop a novel and clean smelting process for the comprehensive utilization of Hongge vanadium titanomagnetite (HVTM), the effect of Al2O3 on the gas-based direct reduction behavior of HVTM pellet (HVTMP) under simulated shaft furnace atmosphere was systemically investigated in this study. It was found that the reduction rate was accelerated by Al2O3 at the initial stage due to the increase of original porosity of HVTMP; however, as the reduction proceeded, the reduction degree significantly decreased with the increase of Al2O3 due to the formation of FeAl2O4, which was difficult to reduce. With the increase of Al2O3, the amount and size of metallic iron grains decreased, and the grains visibly separated from each other. In addition, FeAl2O4 was entrapped with metallic iron grains and remained in the Ti-rich phase, which retarded further reduction. The increased Al2O3 changed the distribution of metallic iron whiskers from close to dispersed clusters and decreased their hardness, leading to the increase of reduction swelling. The findings of this study not only establish a relationship between Al2O3 and its reduction behavior, but also greatly contribute to the effective utilization of HVTM either in blast furnace or shaft furnace.