Thermal Analysis in the Alumina Industry. Part I: Measurements, Observations and Instrumentation

In the work presented here, examples of the thermal analysis of bauxites for the recognition and analysis of both aluminous bearing minerals and other minerals which are presented. In addition to this, samples obtained from Bayer process production facilities were studied by the techniques of DTA, DSC, TG (TGA) and DTG for both product and by-product (red mud). Throughout the manuscript, a great deal of information is included regarding the thermal analysis instrumentation and its use for such mineral mixtures which may have special requirements for achieving good results. Particular interest is given to the operator choices while using DSC, DTA, and TGA/DTG for the analysis of samples with overlapping transitions. The liberation and elimination of water vapor arising from the dehydroxylation of selected components in product alumina, red mud by-product and bauxite raw material are also discussed. This paper will present the DTA, DSC, TGA and DTG analysis of two Jamaican bauxite ores, a bauxite specimen from northern Australia (Weipa), a Western Australia (Darling Range) bauxite ore, a red mud specimen and a product alumina from the Bayer Process.