Thermodynamic estimation on the reduction behavior of iron-chromium ore with carbon

The thermodynamics for reduction of iron-chromium ore by carbon is discussed. The thermodynamic properties of iron-chromium ore were evaluated from our previous work on the activities of constituents in the FeO . Cr(2)O(3)-MgO . Cr(2)O(3)-MgO . Al(2)O(3) iron-chromite spinel-structure solid solution saturated with (Cr, Al)(2)O(3), and those of the Fe-Cr-C alloy were estimated by a sublattice model. The stability diagrams were drawn for carbon reduction of pure FeO . Cr(2)O(3), (Fe(0.5)Mg(0.5))O . (Cr(0.8)Al(0.2))(2)O(3) iron-chromite solid solution, and South African iron-chromium ore. The evaluated stability diagrams agreed well with the literature data. It was concluded that the lowest temperature for reduction of FeO . Cr(2)O(3) in the iron-chromium ore was 1390 K and a temperature higher than 1470 K would be necessary to reduce Cr(2)O(3) in MgO . (Cr,Al)(2)O(3) in the prereduction process of iron-chromium ore. The composition of liquid Fe-Cr-C alloy in equilibrium with iron-chromium ore was also estimated under 1 atm of CO at steelmaking temperature. The predicted metal composition showed reasonable agreement with the literature values.