Title:
Influence of Calcination Temperature on the Properties of Clay
Author(s):
Mehnaz Dhar and Shashank Bishnoi
Publication:
Symposium Paper
Volume:
362
Issue:
Appears on pages(s):
630-638
Keywords:
calcination, metakaolin, physical properties, reactivity, temperature
DOI:
10.14359/51741017
Date:
6/14/2024
Abstract:
Kaolinite is a major clay mineral found across the globe and thermal treatment is required for its application in the cement industry. The performance of a binder containing calcined clay is governed by the properties of calcined clay that are imparted during the calcination process. The present study focuses on the kaolinite clays calcined in a laboratory muffle furnace at three calcination temperatures i.e., 600°C, 800°C, and 1000°C. The composition of kaolinite clays studied here is very broad to understand the influence of associated minerals on the properties of kaolinite clays. The effect of calcination temperature on physical characteristics such as specific surface area and morphology was studied. The changes in the clay structure were also investigated using X-ray diffraction, thermal analysis, and reactivity. The results show the dehydroxylation process is completed at 800°C, during which crystalline structure breaks down into a disorder metakaolin phase without changing the physical properties of clay. However, clays calcined at 1000°C, showed significant differences in the physical properties as compared to the raw clay which can be linked to the spinel phase. The reactivity was also found to reduce significantly due to the appearance of the spinel phase. The iron impurity associated with the kaolinite clay mineral was found to modify the physical characteristics and enhance the reactivity of clays.