Abstract
Seventy-four surface, drill core, and underground samples representative of the eight industrial seams within the limits of Logan County, West Virginia, were studied by X-ray methods. The coals are of Kanawha (Upper Pottsville) and Allegheny age. Samples, for the most part, were composite.The powder X-ray technique was utilized with a number of variations in specimen preparation. Copper and iron radiation were used with 114. 59 mm cameras employing the Straumanis technique of film calibration.Extraneous crystalline impurities identified through X-ray means alone were kaolinite, quartz, pyrite, calcite, and dolomite in order of decreasing occurrence. Of these mineral impurities, only kaolinite appears to occur with any preferred orientation.Information on the structure of coal derived from the study of these high-volatile bituminous coals was compared with the information obtained from specimens of Pennsylvania anthracite, Cretaceous low rank bituminous, and Pennsylvanian semi-bituminous. Results obtained suggest that the "free" carbon in coal is in the form of graphitic crystallites, as indicated by diffuse halos in the region of the prominent graphite diffraction lines. Volatile matter and moisture in the coal appear as secondary scattering on the film. Slight shifts of the {002} halo indicate a definite change of the graphite crystallite size with coal rank change.Previous literature on the X-ray study of coal is reviewed and discussed.Advantages and disadvantages of the X-ray method are compared with other methods of coal analysis, from the standpoint of structural determinations.
