The Effects of Aluminium Fluoride on the Thermal Behaviour of Kaolin

Abstract

A systematic study has been made of the effects of aluminium fluoride on the thermal behaviour of kaolin, using differential thermal, thermogravimetric, X-ray and electron microscope techniques. It is shown that mullite can be formed at a temperature as low as 600~ that in the presence of alurninium fluoride the exothermic reaction occurs at a lower temperature and is reduced in size; that the size of the mullite crystals is increased as a result of pretreatment with aluminium fluoride.

Application of thermal analysis to mineral synthesis

“…Topaz can be synthesized using different starting materials [2,3,8,9,13,14], as kaolinite-aluminium fluoride mix, corundum-quartz mix with ammonium fluoride, kaolinite-ammonium fluoride mix and quartz-aluminium fluoride mix.…”

“…The wide endothermic peak at 625~ represents the dehydration of kaolinite and its reaction with aluminium fluoride with the formation of topaz and mullite. The intensive formation of topaz is represented by the medium and sharp endothermic peak at 750~ very small endothermic peak at 800~ represents the property of topaz to lose silicon tetrafluoride [2,13,14].…”