Kaolinite Synthesis. II. A Review and Discussion of the Factors Influencing the Rate Process

M. C. Van Oosterwyck-Gastuche and A. La Iglesia
Musée royal de l'Afrique centrale, Département de Géologie et de Minéralogie, B-1980 Tervuren, Belgium
Departamento de Cristalografía, Mineralogía, y Mineralotecnia Facultad de Geología, Sección de Genesis y Sintesis Mineral Instituto “Lucas Mallada” del C.S.I.C., Madrid, Spain

Abstract: Kaolinite is synthesized in approximately the same time in three temperature ranges: (1) from 200–250° to 350–400° (hydrothermal processes); (2) from 120 to 175° (semihydrothermal ones); (3) at ordinary temperature. It is thus evident that the rate process cannot be explained by the Arrhenius equation only, but is explained well by considering that kaolinite formation obeys the laws of crystal growth. It occurs only in slightly supersaturated solutions in which the nucleation process is possible and in which a slow and regular rate of growth has been insured. Concentrations calculated from the thermodynamical equilibria correspond to those of the experimental conditions for the low temperature processes. For the higher temperature ones, a similar relationship is delineated, at least as far as the thermodynamical treatment can be carried out.

Key Word: Hydrothermal • Kaolinite • Synthesis • Thermodynamic

Clays and Clay Minerals; December 1978 v. 26; no. 6; p. 409-417; DOI: 10.1346/CCMN.1978.0260604
© 1978, The Clay Minerals Society
Clay Minerals Society (www.clays.org)