Evaporation of the tramp element antimony from molten steel under reduced pressure treatment

Abstract

The evaporation of antimony (Sb) in molten steel under reduced pressure is investigated with the gas phase pressure of 19–670 Pa, smelting temperature of 1823–1973 K and initial Sb content of 0.033–0.1 wt%. The findings indicate that Sb removal efficiency increases when smelting temperature rises or gas phase pressure decreases. However, the initial Sb content has little effect on the Sb removal. The Sb removal ratio can reach 94.1% within 40 min of treatment. The range of the apparent evaporation rate constant, k_Sb, is 0.61 × 10⁻⁵ to 29.13 × 10⁻⁵ m s⁻¹. The evaporation of Sb is limited by the gas phase mass transfer at 1903 K and 19–670 Pa. Additionally, the apparent activation energy of Sb evaporation, E_Sb, is 128 kJ mol⁻¹ at 226 Pa and 1823–1973 K, and the rate of the interfacial reaction severely restricts the evaporation of Sb.