Petrographic Characterization of Kentucky Coals. Final Report. Part V. Pyrite Size/Form/Microlithotype Distribution in Western Kentucky Prepared Coals and in Channel Samples from Western Kentucky and Western Pennsylvania

摘要

Pyrite and marcasite distribution has been characterized in several western Kentucky coals, western Pennsylvania coals, and coals from western Kentucky preparation plants using three parameters of size, morphology, and microlithotype association. A classification system was developed to provide a consistent method for recording different pyrite/marcasite types. Sulfides were microscopically measured and placed in one of six size divisions (<5, 5 to 10, 10 to 40, 40 to 75, 75 to 100, or >150 mu m) rather than absolute size. Five categories (euhedral, framboidal, dendritic, massive, or cleat) describe pyrite/marcasite morphology. The third parameter identifies the microlithotype (vitrite, clarite, inertite, liptite, durite, vitrinertite, trimacerite, or carbominerite) in which the pyrite occurs (not including the measured sulfide). Carbominerite is a mineral/organic association dominated by mineral matter. The percentage of each variable represents the total number of counts per sample and not the volume of pyrite. Throughout the studies, both sulfides are collectively referred to as pyrite unless otherwise specified. This paper describes the different studies which were undertaken to test the usefulness of this pyrite classification system. Systematic trends in pyrite variability were determined for the Springfield coal and Herrin of western Kentucky. Pyrite characterization of the Lower Kittanning coal from western Pennsylvania shows that certain pyrite morphologies can be an expression of the environments deposition of coal bodies. Studies of western Kentucky prepared coals demonstrate that pyrite characterization apparently can provide a method for predicting pyrite behavior and the extent of pyrite removal for specific coals. 77 references, 15 figures, 19 tables. (ERA citation 09:027783)