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Contrasting Cation Distributions in Spinels of Similar Composition

Published online by Cambridge University Press:  02 July 2020

T.R.C. Fernandes
Affiliation:
Institute of Mining Research, University of Zimbabwe, P.O. Box MP 167, Harare, Zimbabwe
C.J. Echer
Affiliation:
National Center for Electron Microscopy, Lawrence Berkeley Laboratory, Berkeley, CA94720
Kannan Krishnan
Affiliation:
National Center for Electron Microscopy, Lawrence Berkeley Laboratory, Berkeley, CA94720
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Extract

Chromite mined from the Great Dyke in Zimbabwe is used for the production of about 180 000 tonnes of ferroalloy per annum, equivalent to about 6% of the world’s supply. The chemical and physical characteristics of the ores, which vary even within the same seam, affect the carbon content of the ferroalloys and hence their commercial value. The purpose of this study is to examine some of the differences between two extremes of chromitites, sheared and unsheared, used in the ferroalloy industry in Zimbabwe to provide a better understanding of the factors that influence the composition of the alloys as a basis for process mineralogy.

The ores consist of chromium spinels (MgAlCrFe)3O4 with a lattice of alternating non-equivalent planes of tetrahedrally coordinated A sites and octahedrally coordinated B sites. The distribution of five major cations (Mg2+, Al3+, Fe2+, Fe3+ and Cr3+) was examined by the technique of electron channelling.

Type
Geology and Mineralogy
Copyright
Copyright © Microscopy Society of America 1997

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References

Refeencs

Spence, J.C.H. and Taftø, J., Journal of Microscopy, 130(1983)14710.1111/j.1365-2818.1983.tb04213.xCrossRefGoogle Scholar
Krishnan, K.M. Scanning Microscopy Supplement 4(1990)157Google Scholar
TRCF gratefully acknowledges the use of facilities at The National Center for Electron Microscopy, Lawrence Berkeley Laboratory, University of California, Berkeley.Google Scholar