Directional Sulfur Removal from Ladle Furnace Slag by Electric Field Strengthening Treatment

Abstract

To develop a better understanding of the resource recycling of ladle furnace slag (LFS) in steel enterprises, electric field strengthening by direct current (DC) is tested as an effective method for sulfur removal from slag. Herein, sulfur removal from CaO–SiO2–Al2O3–MgO–CaF2–S (CSMAFS) slag with 4–12 wt% MgO under 0–6 V is observed at 1773 K, and the mechanism resulting from the electric field on sulfur migration is analyzed. It was concluded that with voltage increases in the range of 0–4 V, the slag network structure depolymerizes, and the melting temperature decreases, which are beneficial to sulfur migration. Mg2+, Ca2+, and other cations in the slag (cathode) are reduced, and S2− migrates to the molten steel (anode) to maintain electrochemical balance. However, sulfur migration reveals an opposite trend when the voltage is 6 V because the electric field force generated at 6 V is not sufficient to resist the combined forces of charge resistance and slag diffusion resistance.