1121.    FURNAS, C. C., AND BROWN, G. C.  Equilibria in the Reduction of Ferric Oxide.  Ind. Eng. Chem., vol. 20, 1928, pp. 507-510; Chem. Abs., vol. 22, 1928, p. 2099.

       New thermal data on Fe₂O₃ have been used with other data in the literature to compute, by means of the 3d law of thermodynamics the equilibrium constants of 7 reactions involved in the reduction of Fe₂O₃ by CO, C and H₂, and one for the decomposition of Fe₂O₃ into Fe₃O₄ and O₂.  Such values of K (equilibrium constant) are given for 100°, 250°, 500°, and 750° based upon actual measurable data, and for 1,000° and 1,500° upon extrapolation data.  It is shown that (a) reduction of Fe₂O₂ by CO and Fe₂O₃ to Fe₃O₄ by H₂ takes place readily at lower temperatures; (b) reduction of Fe₂O₃ by C will not occur to any great extent at low temperatures, but the possibility of such reduction with higher temperatures becomes increasingly greater, a conclusion in harmony with experimental evidence but contrary to popular belief (if the gaseous phase is absent no reduction occurs except at high temperatures); (c) reduction of Fe₂O₃ by H₂ shows that the power of superheated steam to oxidize metallic Fe decreases with temperature, while its ability to oxidize Fe₃O₄ increases with the temperature; (d) data for the decomposition of Fe₂O₃ to Fe₃O₄ and O₂ are not conclusive, but in general the K are lower for 1,000° and 1,500° than the experimental work justifies.  Inconsistencies are ascribed to the variations in solid phases used.  The existence of solid solutions rather than intermediate compounds in the series FeO, Fe₃O₄, Fe₂O₃ may be assumed. Graphs and tables give much condensed information on the matter treated above.