APPLICATION OF THERMOGRAVIMETRIC ANALYSIS FOR ESTIMATION OF TRI-HYDRATE ALUMINA IN CENTRAL INDIAN BAUXITES - AN ALTERNATIVE FOR CLASSICAL TECHNIQUES

摘要

Tri-hydrate alumina or gibbsite (Al_2O_3 · 3H_2O) content in bauxite is a fundamental quality parameter in the Bayer alumina process using low temperature digestion. Classical techniques available for its estimation are time consuming and prone to standard and non-standard sources of error. Extensive studies on analysis of samples from Central Indian bauxite sources using thermogravimetry over varied temperature ranges and comparison with that of the data obtained from classical techniques, have revealed that loss of molecular water at different temperatures in thermo-gravimetry provides a meaningful tool to correlate with tri-hydrate alumina content by applying relevant correction factors derived from the experimental data at different concentrations of tri-hydrate alumina. The studies also have found that the thermogravimetric analysis can be used as a very fast and dependable technique with higher levels of accuracy over classical methods and is free from other interferences. The accuracy levels of the method developed were checked using reference standards.