Influences of CaO/SiO2/MgO/Al2O3 on the Formation Behavior of FeO-Bearing Primary-Slags in Blast Furnace

Slags play an important role in blast furnace operation, and their com- positions are based on the CaO –SiO2–MgO–Al2O3 quaternary system. However, there is not a clear understanding of the effects of gangue on of the formation of FeO-bearing primary-slags process in blast furnace. In this work, the softening and dripping experiments under the blast furnace conditions are designed to explore the influences of CaO-/SiO 2-/MgO-/Al2O3 on the softening and melting properties of FeO respectively. The results indicate that additions of CaO or Al2O3 decrease the starting softening temperature and no dripping behaviors are found in comparison with the base case results when only FeO is used. On the contrary, the addition of SiO2 or MgO rises the starting and ending softening temperature, as well as the dripping temperature. The lowest maximum pressure drop is obtained in the case with addition of SiO2. According to XRD analysis results, the initial phase with CaO addition in the primary-slags should be CaO
Fe3O4 and that with SiO2, MgO, Al2O3 additions are fayalite (2FeO
SiO2), magnesioferrite (MgO
FeO), hercynite (FeO
2Al2O3), respectively.