Thermodynamics of Calcium Ferrite Slags at 1200 and 1300°

Abstract

Abstract Oxygen isobars and liquidus isotherms of the system CaO-FeO-Fe2O3 at 1200 and 1300°C were determined by quenching samples equilibrated with CO2–CO mixtures, The iron liquidus and the melt coexisting with two solids were carefully examined in terms of their composition as well as the equilibrium oxygen partial pressures, p o2 . At 1200°C, p o2 was 10−7.70 atm when the slag coexisted with magnetite and dicalcium ferrite, At 1300°C, the melt region extends to the CaO–Fe2O3 join, where p o2 was 10−0.68 atm (air) or higher. Within the range of p o2 from one order above that at iron saturation to 10−4 atm, the slag composition, p o2 , and the temperature T are related by the equation:log (Fe+ + + /Fe+ + ) ≍ 0.170logp O2 + 0.018 (wt% CaO) + 5500/T − 2.52.Activities of CaO(s), FeO(l), and Fe3O4 (S) in the slag were calculated from the p o2 data by combining the available thermal data and/or by Gibbs-Duhem equation. Resume Les isobares d'oxygene et les isothermes du liquidus du systeme CaO–FeO–Fe2O3 a 120...