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.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
S. Weissberger, Y. Zimmels andI. J. Lin,Met. Trans. B 17B (1986) 433.
L. Pauling, “The Nature of the Chemical Bond”, 3rd Edn (Cornell University Press, Ithaca, 1960) p. 483.
H. P. Rooksby, “The X-ray Identification and Crystal Structure of Clay Minerals” (Mineralogical Society, London, 1961) p. 354.
S. Yariv andE. Mendelovici,Appl. Spectrosc. 33 (1979) 410.
M. L. Garcia-Gonzalez, P. Grange andB. Delmon, “Reactivity of Solids” (Plenum, New York, 1977) 755.
G. W. Brindley, “Kinetics of High-Temperature Processes”, edited by W. D. Kingery (Wiley, MIT, Oxford, 1959) p. 220.
S. Solacolu, “Physical Chemistry of Technical Silicates”, (Publishing House, Bucarest, 1968), pp. 53, 385–386.
L. Von Bogdandy andH. J. Engel, “The Reduction of Iron Ores” (Stahleisen, Dusseldorf, 1971) p. 164.
H. Schmalzried, “Solid-State Reactions” (Academic, New York, 1974) pp. 195–203.
L. Von Bogdandy andH. J. Engel, “The Reduction of Iron Ores” (Strahleisen, Dusseldorf, 1971) p. 90.
A. J. M. Kuipers, PhD thesis, Eindhoven (1978) p. 95 (as quoted by G. Galeczki, DSc thesis, Technion Haifa (1979) p. 3).
A. F. Wells, “Structural Inorganic Chemistry” (Clarendon, Oxford, 1962) pp. 490–492.
L. Pauling, “The Nature of the Chemical Bond”, 3rd Edn (Cornell University Press, Ithaca, 1960) pp. 265–269.
G. W. Greenwood, “The Mechanism of Phase-Transformations in Crystalline Solids” (Institute of Metals, London, 1969) pp. 103–110.
Author information
Authors and Affiliations
Additional information
Deceased November 1987.
Rights and permissions
About this article
Cite this article
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
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF01154010