2020 Volume 60 Issue 7 Pages 1380-1388
In this study, we analyze the softening and melting behaviors of the CaO–FeO–SiO2–Al2O3–MgO system for improving gas permeability in a blast furnace. The temperature of the oxide is increased to 1723 or 1773 K in a CO/CO2 mixture; the softening and melting temperatures and the temperature of penetration into the coke bed are measured. Because the CO/CO2 ratio in the atmosphere influences the stable state of iron or iron oxide, the softening and melting behaviors are investigated for numerous CO/CO2 ratios. We observe that the reduction of the sample progresses in an atmosphere with a high CO/CO2 ratio, and thus, the softening temperature increases. Because the composition of the oxidation phase influences the solidus and liquidus temperatures, the influence of basicity on the phenomena is also investigated, and a method of reducing the difference between the softening and dripping temperatures is discussed.