1452. ---------------. [HOFMANN, K.] [Reduction Mechanism of Iron Oxides in a Gas Stream. II.] Ztschr. angew, Chem., vol. 38, 1925, pp. y715-721; Chem. Abs., vol. 19, 1925, p. 3197.

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Literature Abstracts

1452. ---------------. [HOFMANN, K.] [Reduction Mechanism of Iron Oxides in a Gas Stream. II.] Ztschr. Angew, Chem., vol. 38, 1925, pp. y715-721; Chem. Abs., vol. 19, 1925, p. 3197.

Blast-furnace process is imitated in a simplified manner, using pure H₂ gas and various Fe₂O₃ and Fe₃O₄ preparations. The reaction products are analyzed, and the results are given in curves of H₂ adsorption in relation to time and reduction in relation to temperature. Equilibrium reactions indicate only the tendency of the reaction, because the result is determined by the surface conditions. Fe₂O₃ shows 100% reduction at 550° and 1,000°, with minima at 750° (a) and 925° (b). Granules of 0.05-0.02 mm. diameter are best. Fe₃O₄ exhibits the same character, but is harder to reduce (ferric ferrate). FeO was not found below 564°. Fe₃O₄ forms only in slow processes. The reduction minima are explained (a) by adhesion and (b) by the β-γ transformation. They can be suppressed by addition of MgO. Acid admixtures (SiO₂) do the same but form irreducible slag above 700°.