Use of Coke Dust as Slag De-oxidation Agent for Improving Desulfurization in Si-Killed HC Steels

Experiments were carried out in Si-killed high carbon steels with an innovative and cost effective approach, coke dust as a slag de-oxidation agent to reduce reducible oxides quantity and also its activity in the slag to improve desulfurization efficiency. The flux addition practice was also modified by increasing lime addition compared to synthetic slag, in order to increase the activity of CaO throughout the LF refining process. Various parameters such as the amount of carryover slag, melting point, electrical conductivity, viscosity, activity of FeO, CaO of ladle slag were calculated and its effect on desulfurization efficiency was studied in detail. Finally, an optimized slag composition was suggested using an error function. Industrial trials demonstrated a reduction in reducible oxide content from 5 to 1.5% and the maintenance of an increased CaO activity throughout the refining process improved desulfurization efficiency from 38% to greater than 50%.