Direct Reduction of Iron Oxides with Hydrogen

According to thermodynamics, generally, the reaction of Fe2O3 being directly reduced into Fe by H2 is not allowed to occur. Instead, a middle product will first be created, which will then gradually reduce into iron. During the process of iron oxide reduction, Fe2O3 is first reduced to Fe3O4 by H2, and when the reduction temperature is higher than 570 °C, Fe3O4 is reduced to Fe1–xO, and finally, Fe1–xO is reduced to iron (See Eqs. (3.1) to (3.3) for the reaction formulas). When the temperature is lower than 570 ℃, Fe1–xO is unstable and likely to form Fe. Therefore, Fe2O3 is first reduced into Fe3O4 and the latter is directly reduced into Fe. See (3.1), and (3.4) for the formulas.