Limestone and Dolostone Resources in Kentucky

Garland R. Dever, Jr.

The Kentucky Geological Survey is determining the availability of limestone and dolostone in the State for industrial uses, including flue-gas desulfurization systems used by coal-burning plants, and rock dusting by coal producers. The chemical quality of the stone is a critical factor.

Sampling procedures used for characterizing the chemical composition of limestone and dolostone deposits in the State were evaluated statistically by the University of Kentucky Biostatistics Consulting Unit. Data from sites in Fayette and Madison Counties, which had been sampled by KGS, were used for the analysis.

For the statistical evaluation, we assumed that an important objective of sampling was to determine the mean composition of a ledge of limestone or dolostone. The study showed a relationship between the sampling interval and the reliability of the mean carbonate (or contaminant) value for a ledge. Moderately high reliability (80 to 85 percent) can be obtained by taking three to four samples per ledge. If high reliability (90 percent) of the mean value is desired, samples should be taken at 1-foot intervals. Very high reliability (95 percent or more) would require sampling at ½-foot intervals.

Title III of the Clean Air Act Amendments of 1990 established an initial list of hazardous air pollutants, or air toxics, that are subject to regulation by the U.S. Environmental Protection Agency. The list includes elements commonly found in trace amounts in coal and carbonate rocks.

At the present time, it is not clear if the quantity of trace elements contributed by carbonate rocks during use in industrial processes, such as flue-gas scrubbing, will exceed air- and water-quality standards. The National Geochemical Data Base (NGDB) of the U.S. Geological Survey contains trace-element data for carbonate rocks, and USGS has provided KGS with NGDB analyses for samples from Ohio Valley states. The sample population from the Ohio Valley is relatively small, but the data give an indication of elemental concentrations, which can serve as a guide for evaluating carbonate rocks of the region for industrial uses. Analyses of 749 Ohio Valley samples show the following range of concentrations (in parts per million) for 11 of the elements listed under Title III (antimony, cadmium, and selenium showed no value exceeding the lower analytical threshold):