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The reaction occurring during the wet grinding of kaolinite with CsBr was studied by simultaneous Differential Thermal Analysis -Thermogravimetry (DTA-TG), supplemented by infrared spectroscopy of isothermally treated CsBr disks. The DTA and TG curves were compared with those of untreated kaolinite and of kaolinite mixed or air ground with different alkali halides. A new endothermic DTA peak at 75-115 ~ accompanied by weight loss, is due to the desorption of surface and interparticle water located mainly at the "interface" between the mineral and the salt. A second endothermic peak at about 500 ~ represents the simultaneous dehydroJcylation of the clay and thermal hydrolysis of CsBr. The presence of a separate CsBr phase was identified from two endothermic peaks which characterize melting and boiling of the salt; only mixtures with more than 140 mmol CsBr per 100 g kaolinite show the presence of this phase. All of the CsBr below this concentration occurs in the CsBr-HOH-kaolinite intercalation complex. This degree of saturation is smaller than that obtained previously for CsCl.

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