Activity of CaO in CaO–SiO₂–Al₂O₃–MgO Slags

Abstract

The activity of CaO in CaO–SiO₂–Al₂O₃–MgO slags for blast furnace smelting was determined by a modified slag–metal equilibrium technique with Sn as the solvent metal and a known a_(CaO) slag as the reference slag. Iso-activity contours of CaO in the CaO–SiO₂–Al₂O₃–MgO pseudo-ternary system at w(Al₂O₃)=15% and w(MgO)/w(Al₂O₃)=0.35 were achieved from the measured values. Effects of R (basicity, R=w(CaO)/w(SiO₂)), w(MgO)/w(Al₂O₃) and w(Al₂O₃) on a_(CaO) were discussed. R was significant on a_(CaO) and a_(CaO) increased obviously with the increase of R at 1873 K. a_(CaO) increased with the increase of w(MgO)/w(Al₂O₃) when R is 1.05 and w(Al₂O₃) is 15%. However, the effect of w(MgO)/w(Al₂O₃) on a_(CaO) was not obvious for the slags with R=1.20. With the increase of w(Al₂O₃), a_(CaO) decreased at fixed R=1.05 and w(MgO)/w(Al₂O₃)=0.35. When R is 1.20, a_(CaO) increased with the increase of w(Al₂O₃).