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Coal-Quality Characteristics Of Major Mineable Coal Beds In Kentucky

Cortland F. Eble

Title IV of the Clean Air Act Amendments of 1990, which will control acid deposition, will affect 261 electric utility units at 109 power plants in 21 states. In Kentucky, 17 units belonging to six utility companies will be affected. Phase I, which will begin in 1995, will require coal-burning electric utilities to greatly reduce SO2 emissions. To meet these new compliance standards, utilities in Kentucky and across the United States are switching to burning low-sulfur coal or are installing sulfur-reduction devices (e.g., stack scrubbers, fluidized bed combusters) to help control sulfur emissions.

Although acid deposition control has received a great deal of attention over the past several years, Title III of the Clean Air Act Amendments, "Hazardous Air Pollutants," is also an important, but probably less well known, regulation that will significantly affect the coal and electric utility industries. Of the 189 substances (mainly chemical compounds) cited in Title III that will require monitoring with the implementation of Phase I in 1995, 13 are elements that commonly occur in trace concentrations(generally parts per million) in coal. These 13 elements are antimony, arsenic, beryllium, cadmium, chlorine, cobalt, chromium, lead, mercury, manganese, nickel, phosphorus, and selenium. Coal-burning electric utilities will be required to monitor levels of these elements in the coal feed stock they burn, and coal suppliers probably will be required to test for and report the levels of the elements in the coal they sell to power plants. Because all 13 elements occur in trace concentrations, testing for them requires very specialized and sophisticated testing equipment, which translates into greatly increased costs.

When coal is mined, the raw product consists of coal and rock; rock is contributed from small partings in coal that cannot be avoided during the mining process. To concentrate the coal and get rid of the rock, including pyrite (which is a primary contributor of sulfur in coal), coal is washed or cleaned in large facilities called preparation plants. Most of the trace elements considered under Title III are partially removed by standard coal-cleaning practices. Some elements are reduced by more than 50 percent after cleaning. The fact that virtually all Illinois Basin coal is routinely cleaned prior to shipment and use becomes paramount when trace-element concentrations in coals from different regions are compared. For example, coal from the western United States has gained recent publicity primarily because of its low sulfur content. The trace-element concentrations of these coals are also reported to be very low, which makes them doubly attractive. This attractiveness is somewhat superficial, however, because western United States coals are routinely shipped raw (with no coal cleaning), and much more coal from this region has to be burned in order to achieve the same heating level as Illinois Basin coal. Given these factors, trace-element concentrations in coal are roughly equal between the western United States and the Illinois Basin; some elements, notably mercury, are actually higher in western United States coal, according to currently available data.

One project designed to answer these problems is a cooperative program between KGS, Kentucky Utilities, and the U.S. Geological Survey to study the fate of trace elements in coal in a coal-fired power plant. Since July 1994 we have been sampling feed coal, fly ash, and bottom ash from a coal-burning generating station. This station has four 500-megawatt pulverized air-injection furnaces, each with a peak burn rate of 200 tons per hour. We are sampling unit 1, which burns high-sulfur western Kentucky and southern Indiana coal, and unit 3, which burns low-sulfur eastern Kentucky and southern West Virginia coal. We are also planning to visit some of the mines that supply coal to collect face-channel and bench samples. The samples from western Kentucky and southern Illinois can probably also be used as part of the Illinois Basin coal-quality study. KGS collects, prepares, and runs the following analyses: proximate, ultimate, calorific value, total sulfur, ash fusion, and X-ray fluorescence. The U.S. Geological Survey is testing for trace-element concentrations using atomic absorption and neutron activation. The project is designed for 3 years.

Proposed research by the Indiana, Illinois, and Kentucky Geological Surveys will identify previously unexplored areas of the Illinois Basin where a high probability exists for the development of mineable coal. Because probably less than 5 percent of the Illinois Basin has been explored and developed, a program of this type is critical to the coal industry in the basin, since economic conditions have forced all but a few companies to abandon exploration efforts.

Although some utilities that presently are using Illinois Basin coal are switching to alternative fuel sources in order to comply with the sulfur-reduction mandate, many others are opting to continue burning Illinois Basin coal using sulfur-reduction devices (e.g., stack scrubbers), citing a locally abundant and reliable fuel source. This trend will likely continue into the next century, which emphasizes the continuing need to find and quantify new high-quality coal resources.

We also have a cooperative study with MAPCO coal company to study trace-element variability in their DOTIKI and RITIKI Mines in western Kentucky. In-mine coal, cleaned coal, and preparation-plant refuse will be sampled and tested by KGS. This project will contribute to the Illinois Basin coal-quality study.

The Kentucky Geological Survey continues to maintain and update a comprehensive, computerized coal-quality data base that includes trace-element measurements for over 700 samples of Kentucky coal. Each year the Survey's coal analytical laboratories, which have been in operation since 1989, analyzes several hundred coal samples. Presently, the lab routinely performs proximate (moisture, volatile matter, fixed carbon, and ash yield), ultimate (elemental carbon, nitrogen, hydrogen, and oxygen), total sulfur content, calorific value, ash fusion, and X-ray fluorescence analyses, and plans are being developed to expand the analytical capabilities to include testing for trace elements. This will allow us to continually update and expand our already very large data base so that it may better serve citizens and industry in the Commonwealth.

Link to new coal quality project.

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