High-Sulfur Coals in the Eastern Kentucky Coal Field

Abstract

The Eastern Kentucky coal field is notable for relatively low-sulfur, [open quotes]compliance[close quotes] coals. Virtually all of the major coals in this area do have regions in which higher sulfur lithotypes are common, if not dominant, within the lithologic profile. Three Middle Pennsylvanian coals, each representing a major resource, exemplify this. The Clintwood coal bed is the stratigraphically lowest coal bed mined throughout the coal field. In Whitley County, the sulfur content increase from 0.6% at the base to nearly 12% in the top lithotype. Pyrite in the high-sulfur lithotype is a complex mixture of sub- to few-micron syngenetic forms and massive epigenetic growths. The stratigraphically higher Pond Creek coal bed is extensively mined in portions of the coal field. Although generally low in sulfur, in northern Pike and southern Martin counties the top one-third can have up to 6% sulfur. Uniformly low-sulfur profiles can occur within a few hundred meters of high-sulfur coal. Pyrite occurs as 10-50 [mu]m euhedra and coarser massive forms. In this case, sulfur distribution may have been controlled by sandstone channels in the overlying sediments. High-sulfur zones in the lower bench of the Fire Clay coal bed, the stratigraphically highest coal bed considered here, aremore » more problematical. The lower bench, which is of highly variable thickness and quality, generally is overlain by a kaolinitic flint clay, the consequence of a volcanic ash fall into the peat swamp. In southern Perry and Letcher counties, a black, illite-chlorite clay directly overlies the lower bench. General lack of lateral continuity of lithotypes in the lower bench suggests that the precursor swamp consisted of discontinuous peat-forming environments that were spatially variable and regularly inundated by sediments. Some of the peat-forming areas may have been marshlike in character.« less