Physicochemical Properties of High Alumina Blast Furnace Slag

As a result of the consumption and the rising cost of raw materials for ironmaking, steel producers have increased their utilization of low-cost, low-grade raw materials such as high alumina iron ore. The effect of Al₂O₃ and the Al₂O₃/SiO₂ ratio on the viscosity, surface tension and sulfide capacity of the CaO–SiO₂–Al₂O₃–MgO–TiO₂ blast furnace slag system were studied in the present work. At a fixed CaO/SiO₂ ratio of 1.20, 9 mass pct MgO, and 1 mass pct TiO₂, the viscosity increases with an increase in Al₂O₃ content at a range of 16–24 mass pct, and decreases when the Al₂O₃ is higher than 24 mass pct. Increasing Al₂O₃/SiO₂ from 0.47 to 0.92 causes a slight decrease in viscosity of the slags and has an opposite effect when Al₂O₃/SiO₂ is more than 0.92. The surface tension increases with increasing Al₂O₃ content at a fixed Al₂O₃ content and Al₂O₃/SiO₂ at a fixed CaO content. The desulfurizing capacity decreases with increasing of Al₂O₃ content, while increases with increasing Al₂O₃/SiO₂ at a fixed CaO content.