Advances in the characterization of industrial minerals
The use of minerals by man is as old as the human race. In fact the advancement of human civilization has been intimately associated with the exploitation of raw materials. It is not by chance that the distinction of the main historical eras is based on the type of raw materials used. Hence the passage from the Paleolithic and Neolithic Age to the Bronze Age is characterized by the introduction of basic metals, mainly copper, zinc and tin, to human activities and the Iron Age was marked by the introduction of iron. Since then the use of metals has increased and culminated in the industrial revolution in the mid-eighteenth century which marked the onset of the industrial age in the western world. However, during the past 50 years, although metals were equally important to western economies as they had been previously, the amount of metals extracted annually in western countries has decreased significantly and metal mining activity shifted mainly to third world countries (in Africa, South America, Asia) and Australia, due to economic and environmental constraints. At the same time the role of industrial minerals has become increasingly important for the western economies and today, in developed EU countries, the production of industrial minerals has surpassed by far the production of metals. In some EU countries, metal mining activities have stopped completely. The importance of industrial minerals is expected to increase further in the future.
Thermal Analysis in the Characterization and Processing of Industrial Minerals
Published:January 01, 2010
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.