Effect of fluorspar on the interfacial reaction between electric arc furnace slag and magnesia refractory: Competitive corrosion-protection mechanism of magnesiowustite layer

Abstract

The interfacial reaction between the CaO-SiO2-FeO-Al2O3-MnO-MgO-xCaF2 (CaO/SiO2 = 0.9-1.2, x = 0-10 wt %) type electric arc furnace (EAF) steelmaking slag and magnesia refractory was investigated. Using a microscopic analysis, the thickness of the (Mg,Fe)O, magnesiowustite solid solution (intermediate) layer at the slag/ refractory interface was measured. The thickness of the solid solution layer is affected by both slag penetration and refractory dissolution. Since the CaF2 in the slag affects the interfacial reaction between the slag and the refractory, it impacts the thickness of the solid solution layer. In addition, the depth of refractory dissolution was determined by changing the MgO content in the slag, and the depth of slag penetration was also quantitatively measured. Through these experiments, the refractory corrosion-protection mechanism by the CaF2-containing EAF slag was identified. Finally, the critical CaF2 content (= approx. 3 wt%), which had no significant effect on refractory corrosion, was proposed.