Effect of Slag Composition on Dephosphorization and Foamability in the Electric Arc Furnace Steelmaking Process: Improvement of Plant Operation

Abstract

The effect of slag composition under M'O (monoxide, M = Fe,Mg) saturation and fully liquid conditions on dephosphorization and slag foamability was evaluated in an electric arc furnace (EAF) steelmaking plant operation by considering thermodynamics and phase equilibria. It was confirmed that M'O saturation slag is more favorable for higher dephosphorization than fully liquid slag due to its high activity of CaO as a thermodynamic driving force. As a quantitative measure of slag foamability, the foaming index was clearly dependent on the temperature and slag composition. Moreover, foam stability was evaluated by applying the predominance stability diagram based on phase equilibria. Consequently, it can be suggested that an efficient direction for dephosphorization and slag foaming during the EAF process is to generate high CaO activity as well as small amounts of M'O monoxide and dicalcium silicate (Ca2SiO4) compounds.