Mullitisation behaviour of calcined clay-alumina mixtures

Plastic aluminous clays are abundantly available in Tamilnadu. However, at present the utilization of these clays is very low due to lack of detailed characterization. In the present work, the green and fired characteristics of clays obtained from three different locations in Tamilnadu (Udayarpalayam, Panruti and Neyveli) have been investigated to assess their potential use as raw materials. Physical properties, plasticity index, particle size analysis, chemical analysis, X-ray diffraction and thermal analysis of these clays have been carried out. Physical properties such as density, bending strength, X-ray diffraction and scanning electron microscopy of the fired samples have also been carried out. The properties of the above three clays are compared with each other. The results show that these clays are plastic in nature containing a moderate amount of impurities with high alumina content.

Characterization of aluminous clays from Tamilnadu

This paper includes characterization of three industrially important clays from three different regions of the country: Taldi clay from Purulia district of Eastern Region, Kerala clay from Quilon district of Southern Region and Bikaner clay from Bikaner district of Western Region.Taldi and Kerala clays were found to contain mainly kaolinite (93.5% and 86.33% respectively) with quartz as an impurity. A little amount of a micaceous mineral was also found to be present in Kerala clay. Surface area, cation exchange capacity and moisture absorption were found to be very low for these clays showing high crystallinity of the mineral present in them.Bikaner clay was found to contain mainly montmorillonite with a little amount of kaolinite and quartz. It was observed that the dehydroxylation took place at a lower temperature and in one step. It was found to have large surface area, high cation exchange capacity and moisture absorption capacity indicating disorderedness of the clay structure.

Characterization of Three Indian Clays

The paper embodies characterization and rehydration of the clay from Bikaner district of Rajasthan. DTA and XRD indicated that the clay contained predominantly montmorillonite with kaolinite and quartz as impurities. The behaviour of the clay on dehydroxylation was found similar to an ‘abnormal montmorillonite’. DTA and TGA study suggested that the clay regained lost water completely on rehydration after being heat-treated up to 400°c, but the rehydration was comparatively poor when the clay was heated at higher temperatures. Maximum water adsorption was noticed for the sample heat-treated at 200°C.

T. C. Rao

Papers

Characterization of Three Indian Clays

Some important characteristics of Bikaner clay