Quality of lignites in three areas of the Gulf Coast province
Crowley, S.S.; Warwick, P.D.; SanFilipo, J.R.; Law, S.J.; Aubourg, C.E.
Abstracts with Programs - Geological Society of America 30(7): 175
The distribution of coal quality parameters were determined for the following areas in the Gulf Coast Province: the Sabine Uplift, Northeast Texas, and Central Texas. This work was done as part of the U. S. Geological Survey's (USGS) National Coal Resource Assessment (NCRA) program. Estimates of mean coal quality parameters in the study areas are based on both public and confidential data. Sources for coal quality data include mining permits, the Bureau of Economic Geology at The University of Texas at Austin, Louisiana Geological Survey, USGS National Coal Resources Data System, mining companies, and new samples collected by USGS. Of approximately 600 samples, public data include 288 drillhole or channel samples from 111 locations.In the three areas, thickness-weighted averages of quality parameters are generally very similar for lignites that are primarily from the Wilcox Group (Paleocene-Eocene). Mean moisture values are about 34 percent for all areas, mean ash yields range from 12 to 15 percent, and mean calorific values range from about 5800 in Northeast Texas to 6900 Btu/lb in the Sabine Uplift (all proximate data are on an as-received basis). Mean total sulfur values are low, ranging from 0. 8 percent in the Sabine Uplift area to 1.2 percent in Central Texas. Total sulfur is comprised primarily of organic sulfur, which ranges from about 0.4 to 0.9 percent. Arsenic concentrations in the three areas are generally low, ranging from 3.5 to 4.6 ppm (all trace element data are on an as-determined, whole-coal basis). Mercury levels for each of the areas are about 0.2 ppm. Mean lead levels are only 3.5 ppm in the Sabine Uplift area, but are 18.5 ppm in Central Texas. Selenium levels are highest in the Sabine Uplift area (mean concentrations of 13 ppm) and lowest in both Northeast Texas and Central Texas (5.6 ppm). Future work in the Gulf Coast Province will include studies of the possible origin and geologic controls on the distribution of these quality parameters, plus additional work on the lignites and coals from South Texas, Mississippi, and Arkansas.