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Conductimetric investigations on the dissolution of metakaolinite in dilute hydrofluoric acid. Structural implications

Published online by Cambridge University Press:  09 July 2018

M. Murat
Affiliation:
Institut National des Sciences Appliquees (INSA) de Lyon, Laboratoire de Chimie Physique Appliquee et Environment, Bat. 404, 20 av. A. Einstein, 69621 Villeurbarme Cedex, France
M. Driouche
Affiliation:
Institut National des Sciences Appliquees (INSA) de Lyon, Laboratoire de Chimie Physique Appliquee et Environment, Bat. 404, 20 av. A. Einstein, 69621 Villeurbarme Cedex, France

Abstarct

Conductimetric curves based on dissolution in dilute HF of a series of metakaolinite samples prepared by thermal dehydroxylation of kaolinite in air from 500°C to 987°C, have been interpreted in terms of (i) short-time conductivity variation, and (ii) specific initial dissolution rate (rsi). The first parameter has been correlated with a disorganization factor (Fd, equal to unity for an entirely amorphous silica-alumina mix) which does not exceed 0·52 for metakaolinite and, like rsi, reaches a maximum for samples prepared at about 720–750°C. These results, which agree with other data obtained by calorimetry and infrared spectroscopy, show that metakaolinite is never entirely amorphous and has a degree of disorder which varies with the conditions of preparation, and increases for samples which have been mechanically treated by grinding.

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1988

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