Abstract
Diffusion mechanisms with moving reaction interfaces involved in the reduction process of oolitic iron oxide, containing small goethite particles in a kaolinite matrix, are presented. Reduction was effected by means of CO gas at 950° C, with the oolite already transformed by dehydroxylation into haematite particles and a metakaolinite matrix. The haematite particle under the CO + O → CO2 reaction taking place at its external surface develops concentric layers with unreacted haematite at the core enclosed by magnetite wustite and metallic iron, in that order. In the matrix between particles, “bridges” of a two-phase mixture of hercynite and fayalite develop by diffusion of iron ions and “reactive transport” of oxygen (by means of CO2 molecules), thereby permitting coarsening of the metallic particles. Detailed models are presented for the diffusion mechanisms and reactions involved, and the thermodynamical picture is brought out.
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Deceased November 1987.
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Nadiv, S., Weissberger, S., Lin, I.J. et al. Diffusion mechanisms and reactions during reduction of oolitic iron-oxide mineral. J Mater Sci 23, 1050–1055 (1988). https://doi.org/10.1007/BF01154010
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DOI: https://doi.org/10.1007/BF01154010