Effects of CaF2 on the direct reduction of beach titanomagnetite at different temperatures

Abstract

AbstractEffects of CaF2 on the mineralogical composition and microstructure of reduction products at different temperatures during direct reduction of beach titanomagnetite is investigated. In the absence of CaF2, armalcolite and a large number of small‐size metallic iron particles in reduction products at different temperatures prevented the separation of Ti and Fe. The metallization rate of reduction products was only 90.32 wt% at 1350°C. CaF2 reduced the activation energy of reduction reaction and promoted the reduction of armalcolite, further achieving the separation of Ti and Fe on the mineral phase. When 5 wt% CaF2 was added at 1250°C, the metallization rate of reduction products could reach 90.88%. The effect of CaF2 on the metallization rate was better than that of increasing temperature by 100°C. Besides, CaF2 also reduced the melting point and viscosity of the roasting system, and significantly promoted the aggregation and growth of metallic iron particles, thus optimizing the conditions for the separation and enrichment of Ti and Fe, respectively. Adding 10 wt% CaF2 promoted the growth of MgTi2O5 into a mineral with regular boundary, which created conditions for the recovery of titanium resources. By comparison, the promotion effect of CaF2 on the increasing the metallization rate of reduction products, aggregation and growth of metallic iron particles was obviously better than that of increasing the reduction temperature without CaF2. Therefore, CaF2 could also significantly reduce the energy consumption on the basis of promoting the separation of Ti and Fe.