The Formation of Illitic Clays from Kaolinite in KOH Solution from 225°C to 350°C

Huang Wuu-Liang
Exxon Production Research Company, P.O. Box 2189 Houston, Texas 77252-2189

Abstract: Kaolinite was converted into illitic clays in a 2.58 m KOH solution in gold capsules using cold-seal pressure vessels at 225°, 250°, 300°, and 350°C and 500 bars. The XRD shows that the major reaction products are illitic clays with no interlayer expandability. The TEM shows that the illitic clays appear mainly platelet-like with a K/Si ratio close to that of muscovite/illite. The extent of the conversion was monitored by measuring the XRD peak ratio of muscovite (illite) and kaolinite in quenched run products. The results reveal that kaolinite converts to muscovite/illite in the KOH solution at an initial rate two to three orders of magnitude faster than that of similar reactions at near-neutral conditions.

Key words: Illite • Illite synthesis • Kaolinite • Kinetics

Clays and Clay Minerals; December 1993 v. 41; no. 6; p. 645-654; DOI: 10.1346/CCMN.1993.0410602
© 1993, The Clay Minerals Society
Clay Minerals Society (www.clays.org)