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Quantitative Determination of Hematite and Goethite in Lateritic Bauxites By Thermodifferential X-Ray Powder Diffraction

Published online by Cambridge University Press:  02 April 2024

T. Boski  and
A. J. Herbillon
T. Boski
Affiliation:
IFAQ, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium
A. J. Herbillon
Affiliation:
Centre de Pédologie Biologique du CNRS, B.P. 5, F-54501 Vandaeuvre, France
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Abstract

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An X-ray thermodifferential powder diffraction method for the quantitative determination of goethite and hematite in lateritic bauxites has been developed and consists of measuring the integrated intensities of the 012 line of hematite before and after heating the sample at 900°C and of correcting the obtained values by the X-ray mass absorption coefficient of either the untreated or heated matrix. From the corrected line intensities and the chemical analyses, the amounts of iron to be allocated to goethite and hematite in the untreated samples can be estimated. The actual content of goethite and hematite in a sample is calculated by taking into account the degree of Al substitution in each of these minerals. The method was tested on artificial mixtures of goethite and hematite and subsequently used to analyze 98 auger drill samples from lateritic bauxites of Guinea Bissau. The estimated precision of the determination of goethite and hematite content was ±2% (absolute). The method can not be applied to samples containing < 10% Fe2O3 (on a whole weight basis) unless preconcentration is carried out.

Keywords

BauxiteGoethiteHematiteIronMineral analysisThermal treatmentX-ray powder diffraction
Type
Research Article
Information
Clays and Clay Minerals , Volume 36 , Issue 2 , April 1988 , pp. 176 - 180
Copyright
Copyright © 1988, The Clay Minerals Society

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