Reduction equilibria of the calcium ferrites in the Fe‐Fe₂O₃‐CaO system as a function of oxygen concentration and temperature

Abstract

The results of isothermally conducted reduction tests on the calcium ferrites CF 2+F (= 20 mol. % CaO), CF2 (= 35 mol. % CaO), CF (= 50 mol. % CaO) and C 2F (= 66.7 mol. % CaO) with CO/C02-bearing gases of changing composition in the temperature range between 700 and 1100°c lead both to a plot of the specimen's weight loss as a function of the test duration with the reduction potential CO~of the Professor (em.) Dr-Ing, Eberhard Schiirmann, Institut fur Eisenhiittenkunde und Giebereiwesen, TV Clausthal, Clausthal-Zellerfeld; Dr-Ing, Urban Janhsen, Abteilungsleiter, Forschung Hochofenmetallurgie, Thyssen Stahl AG, Duisburg, Germany. steel research 64 (1993) No. 7

Calcium‐Iron Oxide as Energy Storage Medium in Rechargeable Oxide Batteries

“…Numerous authors studied calcium‐iron oxides . The special emphasis on the thermodynamics and the redox kinetics in conditions similar to ROB operation is most relevant here . However, these studies address the reduction process of sinter ore in blast furnaces for steel production.…”

“…However, these studies address the reduction process of sinter ore in blast furnaces for steel production. The phase CaFe 3 O 5 is rarely mentioned and, if so, regarded as an intermediate phase when reducing lime‐containing iron oxide . Instead, the authors focus on the so‐called brownmillerite phase Ca 2 Fe 2 O 5 because of its stability over a wider range of oxygen partial pressures.…”

Lattice Parameter and Redox Equilibria in CaO-containing Wustite.

“…Therefore, many works have been done by using various methods. 1,2) On the other hand, it was reported that the lattice parameter of pure wustite measured at room temperature changed almost linearly with oxygen content in wustite. 3,4) Moreover, it was found that the lattice parameter of CaO-containing wustite increased with an increase in CaO content of the wustite at constant oxygen potential.…”

“…(2) and (3) The solubility of CaO was estimated to be ϳ9 mol% in the wustite equilibrated with both metallic iron and C 2 F.…”

<i>In situ</i> Observation of Reduction Behavior of Multicomponent Calcium Ferrites by XRD and XAFS

“…Regarding a quasi-binary system, the Baur-Glaessner diagram, 10) which indicates the phase equilibrium for the oxygen potential and the temperature, was experimentally studied well. Kimura et al 11) studied the changes in the valence states and local structure of Fe and Ca in quasibinary calcium ferrites by X-ray absorption spectroscopy and derived their reduction rates.…”