ABSTRACT
The oil embargo of 1973–1974 clearly demonstrated the impact of national dependency on foreign oil imports. Furthermore, environmental issues have become significant factors in coal economics, restricting usage in terms of quality and increasing coal processing costs. US coal resources can be categorized as lignite, sub bituminous, bituminous, and anthracite. The degree of change of chemical composition of coal is called the rank of that coal. Lignite is the lowest-rank and anthracite the highest-rank coal. Roughly three-fourths of the domestic supply of surface-minable coal is in the western half of the nation. Nearly equal amounts of underground reserves are found in the east and the west. The price of coal is determined by a complex variety of factors, including rank (related to depth of seam, which is variable), location, quantity purchased, contract arrangements, and quality. Using slurries of commercially pulverized coal and preconditioned culture from pyrite enrichment, extensive removal of pyritic sulfur has been demonstrated.
