Activity of Iron Oxide in Slag with Nepheline Syenite Added as a Flux

Abstract

Although fluorspar has been widely used as a flux for steelmaking slag, there is a strong incentive to explore alternatives. As one of the candidates for such substances, “nepheline syenite” has been investigated in terms of slag fluidity and lime dissolution rate. The present study aimed at clarifying the homogeneous liquid region and Fe_xO activities in the CaO–Fe_xO slags with nepheline syenite added at 1673 K. When the molar ratio of nepheline syenite/CaO was below 0.658, the substitution of CaO with nepheline syenite raised the Fe_xO activity as well as CaF₂. The effect of the nepheline syenite addition on slag basicity was discussed by means of the reduction-oxidation reaction of Fe³⁺/Fe²⁺.