Desulfurization of Plain Carbon Steel by CaO-Al2O3-SiO2 and CaO-Al2O3-SiO2-X (X = Na2O, SrO) Synthetic Slags

Synthetic slag process decreases sulfur and phosphorus contents of steel, improves inclusion removal, protects steel from atmosphere and prevents temperature drop of the liquid steel in the ladle. In this study, the synthetic slags of ternary CaO-Al2O3-SiO2,and quaternary CaO-Al2O3-SiO2-Na2O and CaO-Al2O3-SiO2-SrO systems were pre-melted and then were kept in contact with the liquid steel in a high frequency induction furnace. The results showed that the optimum reaction time for desulfurization is 15 minutes and the desulfurization efficiency for ternary slag is 33% whereas for the SrO- and Na2O-containing quaternary slags are 34% and 7%, respectively. Furthermore, it was shown that the desulfurization efficiency for SrO-containing slag can be obtained more than doubled (from 34% to 77%) by employing covered crucibles.