Phase and chemical equilibria in the melt (Fe–Si–C)–Slag (CaO–Al2O3–SiO2)–Gas (O2–SiO–CO) system

The equilibrium compositions of high-silicon metallic melts coexisting with CaO–Al 2 O 3 –SiO 2 slag are determined. The dependence of the activity a of silicon in ferrosilicon melts is formulated as activity isolines on the Fe–Si phase diagram. The dependence of log on x Si and T is determined at 1823, 1873, and 1973 K. The influence of which depends on x Si and T , on the equilibrium composition of the gas phase is studied. Data on the activity of silicon dioxide in CaO–Al 2 O 3 –SiO 2 slags is analyzed and corrected. At fixed temperature, each alloy of specified composition corresponds to only one value of represented on the concentration diagram by an activity isoline. In the presence of carbon, all the high-silicon alloys may be obtained at T ≥ 1973 K, with > 0.8. At 1873 K, when > 0.9, only alloys with