THERMODYNAMIC PROPERTIES OF CaO-SiO2-MgO-Al2O3-B2O3 SLAG SYSTEMS AT 1773 K

In this research, the activity of CaO in a CaO-SiO2-MgO-Al2O3-B2O3 blast furnace slag system at T = 1773 K was measured using the reference slag method with Sn as the metal solvent and CaF2-CaO as the reference slag. Based on the obtained experimental results, the iso-activity diagram of CaO in the CaO-SiO2-MgO-20%Al2O3-2.2%B2O3 slag system at 1773 K was drawn. The effects of R(w(CaO)/w(SiO2)) and w(MgO)/w(Al2O3) on the activities and activity coefficients of CaO were also discussed. The results show that when w(Al2O3) = 20 %, w(MgO)/w(Al2O3) = 0.50 and w(B2O3) = 2.2 %, the activities and activity coefficients of CaO in the blast furnace slag increase with an increase in R. When w(Al2O3) = 20 %, R = 1.30 and w(B2O3) = 2.2 %, the activities and activity coefficients of CaO in the blast furnace slag increase with an increase in w(MgO)/w(Al2O3).