Thermal behaviour and microstructure studies of red mud containing marl

Abstract

Red mud is an industrial waste due to Bayer's process arising from aluminium extraction containing many ceramic oxides such as Al2O3, TiO2, Fe2O3 and SiO2. Red mud as a waste material causes an environmental problem, which cannot be utilised directly without any pre-process due to Na2O content. In this study various composition of red mud and marl mixtures were studied which were fired up to 1473 K. After firing at various temperatures new reaction products were emerged namely silicates, calcium aluminates and Na2O in fine crystalline or amorphous morphologies in the final microstructure. Microstructural studies were carried out by optical microscopy and SEM on fired samples. The best result obtained through this study was 50% added marl samples which was fired at 1273 K. It was found that with increasing firing temperature resulted in higher glassy phase and improved microstructures.