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Kinetic approach to the mineral reaction processes during hydrothermal treatment of a saponitic clay

Published online by Cambridge University Press:  09 July 2018

J. Cuevas ,
A. Garralon ,
S. Ramirez  and
S. Leguey
J. Cuevas
Affiliation:
Dpto. de Químiea Agrícola, Geología y Geoquímica, Universidad Autónoma de Madrid. Cantoblanco S/N., 28049 Madrid, Spain
A. Garralon
Affiliation:
Dpto. de Químiea Agrícola, Geología y Geoquímica, Universidad Autónoma de Madrid. Cantoblanco S/N., 28049 Madrid, Spain
S. Ramirez
Affiliation:
Dpto. de Químiea Agrícola, Geología y Geoquímica, Universidad Autónoma de Madrid. Cantoblanco S/N., 28049 Madrid, Spain
S. Leguey
Affiliation:
Dpto. de Químiea Agrícola, Geología y Geoquímica, Universidad Autónoma de Madrid. Cantoblanco S/N., 28049 Madrid, Spain
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Abstract

In the course of hydrothermal experiments with a saponitic clay, evidence for the dissolution of the accessory sepiolite and the formation of smectite has been detected above 120°C Hydrothermal reactions with a clay to water ratio of 1:3 were performed at temperatures of 60, 90, 120, 175 and 200°C with time intervals of one month to one year.

The BET surface area and cation exchange capacity (CEC) are correlated with the sepiolite and the smectite content determined from XRD data. These relations have been used to recalculate the time dependence of the mineral contents in the time/temperature conditions of the experiments. The Ea values obtained for sepiolite dissolution (7-18 kcal/mol) or smectite formation (4.8-5 kcal/mol) indicate that sepiolite dissolution controls the rate of the process. Both results fit an apparent firstorder reaction and the system seems to evolve to a stable mineral composition in a short time period, ranging from one to 10 years as temperature decreases.

Type
Research Article
Information
Clay Minerals , Volume 33 , Issue 3 , September 1998 , pp. 409 - 421
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1998

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