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The Determination of Low Levels of Quartz in Commercial Kaolins by X-ray Diffraction

Published online by Cambridge University Press:  10 January 2013

N.J. Elton ,
P.D. Salt  and
J.M. Adams
N.J. Elton
Affiliation:
ECC International, John Keay House, St. Austell, Cornwall, PL25 4DJ, England
P.D. Salt
Affiliation:
ECC International, John Keay House, St. Austell, Cornwall, PL25 4DJ, England
J.M. Adams
Affiliation:
ECC International, John Keay House, St. Austell, Cornwall, PL25 4DJ, England
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Abstract

Legislation in the United States and Canada requires labelling of products containing ≥ 0.1 wt.% crystalline silica. Kaolin clays are used in a variety of industries and usually contain low levels of total (i.e., respirable plus non-respirable) quartz, even after beneficiation. X-ray diffraction procedures have been developed here which are suitable for the quantification of total quartz in commercial kaolins with accuracy sufficient to satisfy the legislation. Separation and analysis of the respirable fraction is not addressed in this paper; however, the procedures described would be applicable to such samples if sufficient were available. Use of the 50.1° 2θrather than the 26.6° 26 (CuKα) quartz peak avoids most of the potential problems of overlap with reflections from other accessory minerals. It is shown that profile fitting techniques and optimised experimental procedures allow the determination of quartz in bulk samples to ± 0.03 wt.% (95% confidence) at the 0.1 wt.% level, and ± 0.1 wt.% at the 1.0 wt.% level, with tolerable data collection times.

Type
Research Article
Information
Powder Diffraction , Volume 7 , Issue 2 , June 1992 , pp. 71 - 76
Copyright
Copyright © Cambridge University Press 1992

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