Eric J. Trinkle

Ragged edge of the Herrin (No. 11) coal, Western Kentucky

Abstract The Herrin (No. 11) coal in western Kentucky is normally a bright-banded, high-vitrinite, high-sulfur coal. Three sites have been found where the coal deviates from the expected appearance. In Union County, a site known only from a literature description, the upper two-thirds of the coal was described as a cannel. In Ohio County a thin, truncated section of the Herrin coal has a greater abundance of liptinite- and inertinite-rich microlithotypes towards the top of the seam. The various microlithotypes were frequently found in brecciated assemblages. In Hopkins County the Herrin coal was found to be largely a coarse breccia of oxidized macerals cemented by calcite. A marine limestone was present as a parting within the coal. Each occurrence represents the edge of the coal. The sites varied in the energy of the environment and perhaps also in proximity to marine waters.

Coal microlithotype response to froth flotation in selected Western Kentucky coals

Abstract Seven coals representing four western Kentucky coal seams and the coal rank range from high volatile C to high volatile A bituminous were selected for bench-scale froth flotation processing. Each coal was represented by two splits of the run-of-mine coal: a 12.7 mm × 0 fraction (crushed to 28 mesh × 0) and a 28 mesh × 0 fraction. The original 28 mesh × 0 split was found to be higher in the inertinite macerals fusinite and semifusinite than the coarser fraction. The separation of the inertinite macerals, expressed as the microlithotype inertite, from the vitrinite-rich vitrite and clarite microlithotypes proved to be markedly rank dependent. In the higher rank coals vitrite and clarite were concentrated in the clean coal while inertite was concentrated in the clean product in the high volatile C coals. Whereas in gravity-based coal cleaning only the finest pyrite usually remains in the clean coal, in this study no consistent trend in pyrite-size or pyrite-quantity partitioning was noted.

Petrography of the Paradise (No. 12), Baker (No. 13), and Coiltown (No. 14) coals of the lower portion of the Sturgis Formation (Pennsylvanian) in western Kentucky

Coal rank (based on vitrinite reflectance) and maceral composition were determined for 50 channel and borehole samples of the Paradise (No. 12), Baker (No. 13), and Coiltown (No. 14) coals in the Western Kentucky Coal Field. The three coal beds are in the lower part of the Pennsylvanian Sturgis Formation (Desmoinesian). Coal rank trends for the three coals vary across structural provinces in a similar and predictable manner. Coals in the Moorman syncline in the southeast are predominantly of high volatile C bituminous rank but approach high volatile B bituminous rank within the Pennyrile and Central fault systems that border the Moorman syncline. Westward, across the Central faults, rank of coals is high volatile B bituminous in the Webster syncline but increases to high volatile A bituminous northward, within the Rough Creek fault system. Coal rank in the Henderson basin north of the Rough Creek faults decreases to high volatile C bituminous. The Paradise, Baker, and Coiltown coals have consistently high percentages of total vitrinite (vitrinite and pseudovitrinite) (88% for the Paradise coal; 87% for the Baker coal; 85% for the Coiltown coal) and concomitant uniform low percentages of inertinites (less than 10% for each coal) (dry, mineral-matter-free basis). Total reactives (total vitrinite and liptinites) constitute 91% of the Paradise and Baker coals, and 90% of the Coiltown coal. Comparison of the three coals with stratigraphically lower coals in the Pennsylvanian of western Kentucky indicates that rank trends and maceral composition continue to be predictable, not only across the Western Kentucky Coal Field, but also within a large portion of the Pennsylvanian stratigraphic section.

Maceral Partitioning through Beneficiation of Illinois Basin Coals

Coals from 28 Illinois Basin preparation plants, primarily in western Kentucky, were studied for maceral partitioning around several unit operations. Consideration was also given to two sets of plants with similar designs; in one case cleaning the same seam and in the other case cleaning three different seams. More consistent maceral partitioning was exhibited in the finer fractions than in the coarse coal with the fine clean coal being enriched in vitrinite and the fine refuse being enriched in fusinite plus semifusinite. Comparison of coals prepared through similar operations indicated that a significant difference existed in the maceral partitioning both between different coals cleaned in one plant and between the same coal seam (different mines) beneficiated through similar design plants. The petrographic characteristics of each coal appear to be site specific and include inherent factors, such as maceral-mineral associations, as well as factors imposed during mining.

Maceral and pyrite partitioning through high-gradient magnetic separation of selected western kentucky coals

Abstract The −0.5 inch (−1.27 cm) and −28 mesh (−600 μm) fractions of the run-of-mine coals from seven western Kentucky preparation plants were crushed to 90 percent passing 200 mesh (75 μm) and processed through high-gradient magnetic separation (HGMS). Petrographic analysis of the clean and refuse fractions indicated that the refuse contained nearly the same amount of vitrinite as the associated clean coal. This contrasts with the findings for other fine coals from the same plants where fine refuse had consistently less vitrinite and more fusinite and semifusinite than fine clean coals. Pyrite remaining in HGMS clean coals was significantly finer than pyrite in the refuse. Most of the pyrite in the clean was less than 5 μm in diameter, and, in all but one case, greater than 98 percent of the “clean” pyrite was less than 10 μm.

Association of Coal Metamorphism and Hydrothermal Mineralization in Rough Creek Fault Zone and Fluorspar District, Western Kentucky: ABSTRACT

The ambient coal rank (metamorphism) of the Carboniferous coals in the Western Kentucky coalfield ranges from high volatile A bituminous (vitrinite maximum reflectance up to 0.75% Rmax) in the Webster syncline (Webster and southern Union Counties) to high volatile C bituminous (0.45 to 0.60% Rmax) over most of the remainder of the area. Anomalous patterns of metamorphism, however, have been noted in coals recovered from cores and mines in fault blocks of the Rough Creek fault zone and Fluorspar District. Coals in Gil-30 borehole (Rough Creek faults, Bordley Quadrangle, Union County) vary with no regard for vertical position, from high volatile C (0.55% Rmax) to high volatile A (0.89% Rmax) bituminous. Examination of the upper Sturgis Formation (Missourian/Virgilian) coals revealed that the higher rank (generally above 0.75% Rmax) coals had vein mineral assemblages of sphalerite, twinned calcite, and ferroan dolomite. Lower rank coals had only untwinned calcite. Several sites in Webster County contain various coals (Well [No. 8] to Coiltown [No. 14]) with vitrinite reflectances up to 0.83% Rmax and associated sphalerite mineralization. Mississippian and Lower Pennsylvanian (Caseyville Formation Gentry coal) coals in the mineralized Fluorspar istrict have ranks to nearly medium volatile bituminous (1.03% Rmax). Rank varies between fault blocks and, in places, shows unexpected vertical trends. The regional rank trend exhibited by the fault zones is generally higher rank than the surrounding areas. Sphalerite mineralization in itself is not unique within Illinois basin coals, but if it was partly responsible for the metamorphism of these coals, then the fluid temperature must have been higher within the above mentioned fault complexes. End_of_Article - Last_Page 1456------------

Coal Rank Trends in Eastern Kentucky: ABSTRACT

Examination of coal rank (by vitrinite maximum reflectance) for eastern Kentucky coals has revealed several regional trends. Coal rank varies from high volatile C (0.5% Rmax) to medium volatile bituminous (1.1% Rmax), and generally increases to the southeast. One east-west-trending rank high and at least four north-south-trending rank highs interrupt the regional increase. The east-west-trending rank high is associated with the Kentucky River faults in northeastern Kentucky. It is the only rank high clearly associated with a fault zone. The four north-south-trending rank End_Page 1920------------------------------ highs are parallel with portions of major tectonic features such as the Eastern Kentucky syncline. Overall, though, the association of north-south-trending rank highs with tectonic expression is not as marked as that with the anomaly associated with the Kentucky River faults. It is possible that the rank trends are related to basement features with subdued surface expression. Rank generally increases with depth, and regional trends observed in one coal are also seen in overlying and underlying coals. The cause of the regional southeastward increase in rank is likely to be the combined influence of greater depth of burial and proximity to late Paleozoic orogenic activity. The anomalous trends could be due to increased depth of burial, but are more likely to have resulted from tectonic activity along faults and basement discontinuities. The thermal disturbances necessary to increase the coal rank need not have been great, perhaps on the order of 10-20°C (18-36°F) above the metamorphic temperatures of the lower rank coals. End_of_Article - Last_Page 1921------------