Thermal, Mechanical and Chemical Treatments of the Kaolin Minerals

Abstract

This chapter presents an overview of the spectroscopic analyses of the effects of thermal, mechanical and chemical treatments on the kaolin group minerals. Thermal treatment and the formation of metakaolinite as an intermediate before the crystallization of mullite has been a matter of discussion for more than 70 years. Infrared, including Infrared Emission, spectroscopy, Raman spectroscopy and Magic-Angle-Spinning Nuclear Magnetic Resonance spectroscopy have played a major role in unravelling the reactions and the corresponding structural changes. The use of grinding and its effect on particle size and order/disorder has been extensively studied by in particular infrared spectroscopy. Chemical treatment, especially acid treatment and the leaching of metals has been a more limited subject of research. The effect of irradiation has been introduced in the previous chapter and is explored in more detail in this chapter.