Prototropy in Kaolinite During Percussive Grinding

John G. Miller and T. Dixon Oulton
Department of Chemistry, University of Pennsylvania, Philadelphia 4, Pa. 19104, U.S.A.
Engelhard Minerals & Chemicals Corp., Menlo Park, Edison, New Jersey 08817, U.S.A.

Abstract: When kaolinite undergoes percussive grinding, pronounced changes take place in its i.r. absorption spectrum even in the earliest stages of the grinding when the lattice is not yet destroyed. In this report, attention is directed to the change in the stretching bands of the hydroxyl ions. A remarkably rapid effect on the band of the intralayer hydroxyl ions has been observed and is attributed to a permanent removal of the protons from these ions. Auxiliary measurements of X-ray diffraction, thermal water loss, and DTA were used to corroborate the spectroscopic evidence for this ready prototropy.

Clays and Clay Minerals; December 1970 v. 18; no. 6; p. 313-323; DOI: 10.1346/CCMN.1970.0180603
© 1970, The Clay Minerals Society
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