New data on thermal effects of kaolinite in the high temperature region

DTA study of an Indian Kaolinite has been performed by varying packing density and rate of heating. Both these two parameters influence the intensities of both endothermic and exothermic peaks related to the dehydration, dehydroxylation and then crystallizations of Al-Si spinel, mullite and cristobalite phases. Significantly, the study reveals that mullitization takes place by two separate reactions as indicated by two exotherms in the 1200-1400degreesC range of DTA trace.