4. Thermochemical data relevant to blast furnace operation

4.1 Fe-O system

The Fe-O phase diagram indicates the existence of three stable oxides: Fe ₂ O ₃ (hematite), Fe ₃ O ₄ (magnetite) and FeO _1.056 (wustite) (figure 12 ). The degree of oxidation of oxides is generally expressed by the ratio between the number of oxygen and iron atoms O/Fe: this is 1.5 for hematite, 1.33 for magnetite...