ABSTRACT

Gulf Coast ]ignite occurs mainly in Eocene strata with the majority of the resources occurring in the lower Eocene Wilcox Group. Strippable resources in the Gulf Coast area area about 20 to 25 billion short tons of which one-half are in Texas. Grade (5000 to 7000 Btu/lb, 20 to 50 percent moisture, 10 to 40 percent ash, and 0.5 to 2 percent sulfur) decreases from west to east with progressively younger stratigraphic units. Seams are typically 2 to 10 ft. thick; differences in continuity and grade can be correlated with depositional system.

Large acreages are under lease -- 2.5 million acres in Texas alone. At the near-surface, development drilling is most common whereas exploration drilling is now underway for deep-basin lignite. Deposit size depends on end use, for example, a 150 million ton reserve for power plants and 15 million tons or less for industrial boilers. Mining is by dragline or scrapers at less than 120 ft and stripping ratios of less than 10:1; minimum seam thickness is 2 ft. Reclamation cost is approximately $1000 per acre. Bucketwheel excavator are inevitable as multiseam thin-bed deposits are mined at increasing depths.

All current production is in Texas and was about 21 million tons in 1978. Almost all the production is pulverized fired in mine-mouth plants where lignite produced energy costs 50 cents per million Btu. In Texas, air quality standards (AAQS and PSD) could restrict the siting of future power plants. Future use in atmospheric fluidized bed combustion and medium-Btu gasification is probable. Underground gasification should be commercialized by 1990.

1. Publication authorized by the Director, Bureau of Economic Geology, The University of Texas at Austin 78712.

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