Geological Characteristics of Coal

Abstract

Coal is a complex and diverse material. It is important to consider the geological origins and history of coal as these considerations allow for the categorization of coal into various types. The classification of coal into various types is itself a valuable step towards using coal resources effectively. It is also essential for understanding the various aspects of coal structure and reactivity. In this chapter, we discuss the plant materials that are the precursors of coal in terms of their organic constituents. The chemical structures of plant sugars, proteins, lipids, and other organic components are related to their stabilities and the geochemical processes by which these organic raw materials are eventually converted into various types of coal. We review the basic generic types of coal in terms of precursor material, geochemical history and relate this to appearance and basic physical properties. We introduce the categorization concepts of coal maceral, rank, and lithotype. The qualities and factors that are used to determine coal type are discussed in terms of the distribution and type of coal resources in China. The chapter forms the necessary background to understanding the origin of materials discussed in later chapters and provides a context for the studies we present.