New Washability Diagram Presenting the Petrological Constituents of Coal

CIM Bulletin, 1971

The petrographic components of any particular rank of coal often show some distinct physical and chemical characteristics. Therefore, their proportionate distribution in a coal greatly influences the technological behaviour of the coal. In any size or gravity separation of a coal, the petrographic constituents become segregated to different degrees in some preferred size or specific gravity range. Therefore, a knowledge of the petrographic nature of the washed and/or screened fractions is often considered essential in selecting the most efficient method for coal preparation and in exploring the proper evenues for its utilization. A graphical method is described in this paper to indicate the mineralmatter content and the petrographic components of the washed fractions of a coal at different ash levels of separation in the form of a new washability diagram. This diagram can be conveniently used to assess or predict the petrographic composition of clean coal or sinks corresponding to any desired ash level in the cleans. With the help of this diagram, it is also possible to locate the yield level of cleans at which maximum enrichment of vitrinites and exinites occurs with the least amount of mineral-matter content.

Keywords: Ash, Coal, Density, Maceral, mineral, minerals, Petrographic composition, Petrographic Studies of Indian Coal, specific gravity, Sydney Coal Field, Vitrinite Content, Weight of Total Maceral, Washability, Yield