Activities of FexO in Industrial Slags Used for External Removal of Phosphorous from Hot Metal

Abstract In order to obtain a physicochemical knowledge of complex industrial slags, the activities of FexO in the industrial slags used for external dephosphorization of hot metal performed at practical steelmaking plants in Japan were measured by means of a solid-oxide galvanic cell in a temperature range between 1523 K and 1673 K. XRD study showed the presence of solid phases in all the slags, showing the heterogeneous character of the slags employed. With respect to the effect of CaF ₂ on FexO activity, the FexO activities of the heterogeneous slags were correlated with the ratio X(FeO)/X(CaF ₂ ) . High X(FeO)/X(CaF ₂ ) values corresponded to high FeO activity. This tendency is interpreted based on the phase relationship in a CaO-CaF ₂ -FexO ternary system. A favorable condition for external dephosphorization with less addition of CaF ₂ is discussed.