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Effect of Ca(II)‐ion in Wüstite on its Reduction to Iron
Author(s) -
Dai Yunduo,
Guo Xingmin,
Zhang Jiayun
Publication year - 2006
Publication title -
steel research international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.603
H-Index - 49
eISSN - 1869-344X
pISSN - 1611-3683
DOI - 10.1002/srin.200606427
Subject(s) - wüstite , materials science , metallurgy , isothermal process , diffusion , magnetite , thermodynamics , physics
Fired compacts of hematite doped with different contents of CaO (mass fractions were 3.5, 4.0, 4.5, 5.0 %) were isothermally reduced to wüstite in a CO‐CO 2 gas mixture at 1173K. It was found from X‐ray diffraction investigation that the lattice parameters of wüstite increased with CaO content dissolved in wüstite crystal. The pure wüstite as well as the wüstite doped with CaO were reduced at different temperature. The results showed that the reductions were promoted with increasing CaO content. The higher the content of CaO dissolved in wüstite crystal was, the larger the lattice parameter and the interplanar distances of wüstite became. This expansion was helpful to the migration of Fe ions and enhanced the reduction. At the early stage, the reduction of pure and doped wüstite compacts was controlled by the interfacial chemical reaction step. At the latter stage, the gaseous diffusion was the rate‐determining step for both sample types.