Influence of Atmosphere and Basicity on Softening and Melting Behaviors of the CaO–FeO–SiO₂–Al₂O₃–MgO System

Abstract

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.