Chapter 5: Thermal analysis in the characterization and processing of industrial minerals
The present chapter describes the application of thermal analysis (TA) in the characterization and processing of industrial minerals. An advantage of TA is its sensitivity to short-ranged ‘X-ray amorphous’ materials and (turbostratic) disordered minerals. In addition, it is more sensitive than X-ray diffraction at detecting small amounts of minerals in the case of decomposing minerals that evolve distinctive gases during thermal treatment.
Minerals and rocks undergo several thermal reactions (dehydration, dehydroxylation, decomposition, melting, phase transition, oxidation or recrystallization) which are diagnostic of the substance. Unfortunately, the reactions of the individual components in mineral mixtures often superimpose and the results of TA are strongly influenced by several factors, such as sample preparation, selection of experimental parameters, instrument arrangement, etc.
The present chapter begins with a short theoretical introduction on the principles and methods of TA while the factors that influence TA data and curves are described in more detail as their understanding is most important for interpretation of any measured TA data with respect to mineral structures, material characteristics and behaviour of industrial minerals in technical processes. Note that standardized conditions are essential for reasonable TA data.
Description of ongoing developments of coupled devices for simultaneous thermal analysis (STA) and their application for quantitative analysis is followed by detailed information on diagnostic thermal reactions for important industrial minerals with focus on clay minerals.
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