Hostname: page-component-848d4c4894-4rdrl Total loading time: 0 Render date: 2024-07-03T08:25:35.078Z Has data issue: false hasContentIssue false
  • English
  • Français

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
Get access Rights & Permissions [Opens in a new window]

Abstract

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

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Ambrosi, J. P., Nahon, D. and Herbillon, A. J., 1986 The epigenetic replacement of kaolinite by hematite in laterite—Petrographie evidence and mechanism involved Geoderma 37 283 – 294.CrossRefGoogle Scholar
Black, R. H., 1953 Analysis of bauxite exploration samples Anal. Chem. 25 743 – 748.CrossRefGoogle Scholar
Fitzpatrick, R. W. and Schwertmann, U., 1982 Al-substituted goethite: An indicator of pedogenic and other weathering environments in South Africa Geoderma 27 335 – 347.CrossRefGoogle Scholar
Janot, C.h. Gibert, H., de Gramont, X. and Biais, R., 1971 Etude des substitutions Al-Fe dans des roches latéritiques Bull. Soc. Fr. Mineral. Crystall. 94 367 – 380.Google Scholar
Kampf, N. and Schwertmann, U., 1982 Quantitative determination of goethite and hematite in kaolinitic soils by X-ray diffraction Clay Miner. 17 359 – 363.CrossRefGoogle Scholar
Kampf, N. and Schwertmann, U., 1982 The 5 M NaOH concentration treatment for iron oxides in soils Clays & Clay Minerals 26 401 – 408.CrossRefGoogle Scholar
Kelly, W. C., 1956 Application of d.t.a. to identification of natural hydrous ferric oxides Amer. Mineral. 41 353 – 355.Google Scholar
Klug, H. P. and Alexander, L. E., 1974 X-ray Diffraction Procedures for Polycrystalline and Amorphous Materials 2nd New York Wiley.Google Scholar
Nahon, D. (1976) Cuirasses ferrugineuses et encroûtments calcaires au Sénégal et en Mauritanie: Mem. Univ. Louis Pasteur, Strasbourg 44, 232 pp.Google Scholar
Schulze, D., 1981 Identification of soil iron oxide minerals by differential X-ray diffraction Soil Sci. Soc. Amer. J. 45 437 – 440.CrossRefGoogle Scholar
Schwertmann, U., Cambier, P. and Murad, E., 1985 Properties of goethites of varying crystallinity Clays & Clay Minerals 33 369 – 378.CrossRefGoogle Scholar
Schwertmann, U., Fitzpatrick, R. W. and Taylor, R. M., 1979 The influence of aluminum on iron oxides. Part II. Preparation and properties of Al-substituted hematites Clays & Clay Minerals 27 105 – 112.CrossRefGoogle Scholar
Tardy, Y. and Nahon, D., 1985 Geochemistry of latérites, stability of Al-goethite, Al-hematite, and Fe-kaolinite in bauxites and ferricretes: An approach to the mechanism of concretion formation Amer. J. Sci. 285 865 – 903.CrossRefGoogle Scholar
Yariv, S., Mendelovici, E. and Vilalba, R., 1981 Interactions between the iron and aluminium during the heating of Venezuelan lateritic bauxites. II. X-ray diffraction studies Termochim. Acta 45 339 – 348.CrossRefGoogle Scholar