COAL STRUCTURE.

Abstract

The structure of coal cannot be defined to the same extent as a pure crystalline solid because of its heterogeneous nature. However it does contain definable units and features which repeat throughout the coal and these have distinct physical and chemical properties which can be defined to varying degrees. A knowledge of these structural features is important for understanding coal properties and behaviour during gasification, carbonisation, and combustion. Direct evidence for the structure of coal has been obtained from a wide variety of methods. There have been a considerable number of hypotheses on coal structure but there is a lack of vital information in many areas. It is fair to say that a start has been made on rudimentary models of coal structure and these will form a basis for future developments. The models are illustrative rather than definitive and a considerable amount of further work is needed to understand the various diverse aspects of coal structure, in particular in the nature of the macromolecular structure of coal.