Western coals, inorganic

It is common practice to make a distinction between the inorganic constituents of so-called "Eastern" and "Western" coals By definition. Western coals are those for which the CaO+MgO content exceeds the Fe203 content of the ash, while the reverse is true for Eastern coals [ 1 I The inorganic constituents in Eastern coals, which are principally bituminous in rank, are predominantly in the form of discrete mineral particles. Clay minerals (kaolinite, illite) are usually dominant, followed by quartz and pyrite. The range and typical values of the mineral distribution and ash chemistry of Eastern coals are shown in Table I. These data were determined from computer-controlled scanning electron microscopy (CCSEM), Mossbauer spectroscopy, and other measurements on over a hundred coals. 

These results are in good agreement with those of Glick and Davis (75) who made a comprehensive statistical analysis of the inorganic constituents in 335 whole-seam samples (The Pennsylvania State University Coal Sample Bank). In addition to those minerals listed here in Table V, Glick and Davis distinguished gypsum (all sulfates) and kaolinite. They found the content of kaolinite was mostly less than 15% of the minerals extracted by LTA in coals from the Western Interior Basin and the Illinois Basin as compared to coals from the Appalachian and western basins where kaolinite mostly comprised more than 15 percent of the LTA. 

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