Reporting of Coal Analyses

Although most of the coal analyses are carried out on air-dried samples and the constituent are reported on this basis, analytical results are frequently modified by appropriate correlations allowing the expression to a number of different bases. Table 3.2 indicates how some of these bases are related to the various coal components. 

Because moisture and mineral matter (incorporating the ash) are extraneous to the coal substance, there are different ways to report the analytical data 

Pure coal Mineral matter Total moisture  

Fixed carbon Organic Inorgmiic Ash Inherent moisture Surface moisture 

Dry mineral matter-free (dmmf) Data are expressed in percentage of the coal assumed to be free of both moisture and mineral matter. This theoretical term is mainly used for coal classification and implies that mineral matter has a solid (ash) and gaseous fraction (volatiles originating from clays, carbonates, and oxidation of FeS2, see also Table 3.2). 

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