Search USGS⌕ Search

SEARCH · Search USGS

Results for “Coal Preparation”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2Linked to original sources
USGS2005

Appalachian coal assessment: Defining the coal systems of the Appalachian basin

The coal systems concept may be used to organize the geologic data for a relatively large, complex area, such as the Appalachian basin, in order to facilitate coal assessments in the area. The concept is especially valuable in subjective assessments of future coal production, which would require a detailed understanding of the coal geology and coal chemistry of the region. In addition, subjective assessments of future coal production would be enhanced by a geographical information system that contains the geologic and geochemical data commonly prepared for conventional coal assessments. Coal systems are generally defined as one or more coal beds or groups of coal beds that have had the same or similar genetic history from their inception as peat deposits, through their burial, diagenesis, and epigenesis to their ultimate preservation as lignite, bituminous coal, or anthracite. The central and northern parts of the Appalachian basin contain seven coal systems (Coal Systems A-G). These systems may be defined generally on the following criteria: (1) on the primary characteristics of their paleopeat deposits, (2) on the stratigraphic framework of the Paleozoic coal measures, (3) on the relative abundance of coal beds within the major stratigraphic groupings, (4) on the amount of sulfur related to the geologic and climatic conditions under which paleopeat deposits accumulated, and (5) on the rank of the coal (lignite to anthracite). ??2005 Geological Society of America.

Special Paper of the Geological Society of America↗
USGS1950

Coal resources of the United States, A progress report, November 1, 1950

Interest in the quantity and quality of the coal reserves of the United States has increased greatly since the end of World War II, principally because of the growing realization that the ultimate reserves of petroleum and natural gas, although largely undefined, still. have finite limits. With the greatly increased use of petroleum and natural gas, it has become further apparent that the reserves of these two fuels, whatever their ultimate limits may prove to be, are being consumed at a rate far surpassing that anticipated a few years ago. At some time in the future, therefore, the contribution of coal to the total production of energy in this country must inevitably be enlarged to include some of the needs now served by petroleum and natural gas. Although coal-bearing rocks cover 14 percent of the total area of the United States (fig. 1) and contain enormous reserves, it is equally apparent that reserves of coal also have limits. In the extensively mined sections in the East it is already increasingly difficult to locate new areas containing thick beds of high-rank and high-quality coal to replace areas that have been mined out. Furthermore, a considerable part of the total reserves of the United States consists of coal of lignite and subbituminous ranks and coal contained in thin beds that can be mined only with great difficulty and expense. At the present time, therefore, the depletion of reserves of high-rank and high-quality coal, particularly the Eastern coal that is suitable for the manufacture of metallurgical coke, is a more serious problem than the percentage depletion of the total coal reserves. Recognizing the need for more detailed estimates of coal reserves than those that have been available in the past, the U. S. Geological Survey is now preparing a reappraisal of the coal reserves of the United States in which primary emphasis is placed on the amounts of coal in separate categories according to rank,thickness of coal, and thickness of overburden. Many of the state geological surveys in coal-producing areas are also preparing new appraisals of coal reserves. The increasing volume of geologic data available on the occurrence of coal and the detailed and careful methods now employed in calculating reserves should ultimately provide a more reliable estimate for the coal reserves of the United States than has been obtainable previously, although much additional work remains to be done.

Circular↗
USGS2006

Chemical analyses of coal, coal-associated rocks and coal combustion products collected for the National Coal Quality Inventory

In 1999, the USGS initiated the National Coal Quality Inventory (NaCQI) project to address a need for quality information on coals that will be mined during the next 20-30 years. At the time this project was initiated, the publicly available USGS coal quality data was based on samples primarily collected and analyzed between 1973 and 1985. The primary objective of NaCQI was to create a database containing comprehensive, accurate and accessible chemical information on the quality of mined and prepared United States coals and their combustion byproducts. This objective was to be accomplished through maintaining the existing publicly available coal quality database, expanding the database through the acquisition of new samples from priority areas, and analysis of the samples using updated coal analytical chemistry procedures. Priorities for sampling include those areas where future sources of compliance coal are federally owned. This project was a cooperative effort between the U.S. Geological Survey (USGS), State geological surveys, universities, coal burning utilities, and the coal mining industry. Funding support came from the Electric Power Research Institute (EPRI) and the U.S. Department of Energy (DOE).

Open-File Report↗
USGS1952

Coal resources of Virginia

The U. S. Geological Survey and the Virginia Geological Survey have cooperated in preparing this reappraisal of the coal resources of Virginia, which is based on a study of all information" on the reserves of the State available in the publications and files of the two organizations, supplemented by mine and drill-hole information provided by mining companies and private individuals. Coal is found in Virginia in three widely separated and entirely dissimilar areas: the Southwest Virginia field, or simply the Southwest field, which comprises all or part of Tazewell, Buchanan, Dickenson, Russell, Scott, Wise, and Lee Counties; the Valley fields, a series of long, narrow coal-bearing areas in the Valley of Virginia that are concentrated largely in Montgomery, Pulaski, and Wythe Counties; and the Eastern fields, consisting of two relatively small basins near Richmond and Farmville, respectively. Of the total reserves of the State, about 97 percent are in the Southwest Virginia field. In estimating reserves of the Southwest Virginia field the cooperating agencies were assisted by a series of excellent county reports covering the entire field and by the generous cooperation received from the coal-mining companies. Because of this help, it was possible not only to prepare estimates of reserves in that field by individual coal beds, but to outline most of the important mined-out areas on the bed maps and thus to prepare an estimate that takes into consideration the coal mined and lost in mining prior to January 1, 1951. The Valley fields, which were mined to some extent prior to 1860 and which have an almost continuous production record since 1883, have been mapped and studied in some detail, but the data on the area are in general inadequate and the structure is too complex to permit a detailed estimate of reserves. Estimates of indicated and inferred reserves in six. of the ten Valley fields were prepared, however, and are presented in subsequent pages. The estimates for the Valley fields are on the basis of original reserves, as mine information is too scanty and production figures too generalized to be of value in translating original reserves into remaining reserves. The Richmond basin, the easternmost of the Eastern fields, was first mined in 1748, and operations were carried on almost continuously for 150 yr of more after that date. Activity died rapidly as rail transportation made the more easily mined Appalachian coals available, and the Eastern basins have seen little activity since about 1905. Despite the fact that an all-time total of more than 8 million tons has been taken from the Richmond basin, the data now available on the coal beds are considerably less than those on the Valley fields and it was impossible to estimate the reserves with any degree of accuracy. The reserves of the Eastern fields are therefore omitted from the tables, though the fields are discussed in later sections of this report. Whether presented as remaining reserves (Southwest field) or original reserves (Valley fields) the estimates presented in this report have been calculated on a most conservative basis, and in all probability these estimates will be increased rather than diminished as additional field work is done. Undoubtedly much of the coal reserves shown herein as indicated or inferred reserves will be changed to the measured or indicated category as development work progresses.

Circular↗
USGS1955

Detailed logs of 28 wildcat wells in Lee, Wise, Buchanan, Montgomery, and Dickenson Counties, Virginia

The Clinchfield Coal Company No. 102 well was drilled in the western part of Buchanan County near the Dickinson County line. The well started in the Pennsylvanian Norton formation and originally stopped in the Big Stone Gap shale. It was later deepened during 1950 to a total depth of 5847 but the samples from the deepened hole were not available for study when this report was prepared. The Clinchfield Coal Company kindly made available for study and publication the samples from the surface to a depth of 4508 feet.

Virginia↗
USGS1987

Hydrology of area 59, northern Great Plains and Rocky Mountain coal provinces, Colorado and Wyoming

Hydrologic information and analysis aid in decisions to lease federally owned coal and to prepare necessary Environmental Assessments and Impact Study reports. This need has become even more critical with the enactment of Public Law 95-87, the "Surface Mining Control and Reclamation Act of 1977." This act requires an appropriate regulatory agency to issue permits, based on the review of permit-application data to assess hydrologic impacts. This report, which partially fulfills this requirement, is one in a series of nationwide coal province reports that present information thematically, through the use of a brief text and accompanying maps, graphs, charts, or other illustrations for single hydrologic topics. The report broadly characterizes the hydrology of Area 59 in north-central Colorado and southeastern Wyoming. The report area, located within the South Platte River basin, covers a 16,000-square-mile area of diverse geology, topography, and climate. This diversity results in contrasting hydrologic characteristics. The South Platte River, the major stream in the area, and most of its tributaries originate in granitic mountains and flow into and through the sedimentary rocks of the Great Plains. Altitudes range from less than 5,000 feet to more than 14,000 feet above sea level. Precipitation in the mountains may exceed 40 inches annually, much of it during the winter, and produces deep snowpacks. Snowmelt during the spring and summer produces most streamflow. Transmountain diversion of water from the streams on the western slope of the mountains also adds to the streamflow. Precipitation in the plains is as little as 10 inches annually. Streams that originate in the plains are ephemeral. Streamflow quality is best in the mountains, where dissolved-solids concentrations are generally small. Concentrations increase in the plains as streams flow through sedimentary basins, and as urbanization and irrigation increase. The quality of some mountain streams is affected by drainage from previous metalmining areas, as indicated by greater trace-element concentrations and smaller pH values. However, the large trace-element concentrations decrease rapidly downstream from the metal-mining areas. Because the climate is semiarid in most of the area, the soils are not adequately leached; therefore, flows in ephemeral streams usually have larger concentrations of dissolved solids than flows in perennial streams. Ground water is available throughout the area; yields range from less than 0.1 gallons per minute in the fractured granite aquifer in the mountains to more than 2,000 gallons per minute in the alluvial aquifer of the South Platte River valley. Major bedrock aquifers in order of decreasing age are the Laramie-Fox Hills, Arapahoe, Denver, and Dawson; these aquifers are used for municipal, domestic, and livestock supplies. Alluvial aquifers supply the high-yield irrigation wells. The best quality ground water is found at the center of the major bedrock aquifers, where dissolved-solids concentrations are less than 200 milligrams per liter. The poorest-quality water is usually found near the edges of these aquifers. Water in the coal-bearing Laramie and Denver Formations is locally affected by coal deposits, causing dissolved-solids concentrations to be relatively large. Only one coal mine is now operating in Area 59, the Coors Energy Company surface coal mine, which produced 100,000 short tons of subbituminous coal from the Upper Cretaceous Laramie Formation in 1982. Past coal-mining operations removed more than 130 million tons of coal and lignite from Area 59,99 percent of which came from underground mines. The largest coal production was in Weld and Boulder Counties, Colorado. Hydrologic problems related to surface mining are erosion, sedimentation, decline in water levels, disruption of aquifers, and degradation of water quality. Because the semiarid mine areas have very little runoff, and the major streams have large buffer and dilution capacities, the effects of mining on surface water is minimal. However, effects on ground water may be much more severe and long-lasting.

Colorado, Wyoming↗
USGS1980

Maps showing coal resources of the Crumpler quadrangle, Mercer, McDowell, and Wyoming Counties, West Virginia

Coal Geology The Crumpler quadrangle lies in the Appalachian Plateaus province, with the coal bearing Pocahontas and New River Formations of Pennsylvanian age having a gentle dip toward the northwest. Coal bed maps were prepared (figures 1-7) and resources were estimated (table 1) for seven of the many coal beds in the Crumpler quadrangle (Stricker, 1980, lists the names of the various coal beds in the quadrangle) following methods established by U.S. Bureau of Mines and U.S. Geological Survey, 1976. All of these coal beds crop out at the surface in the quadrangle, have a maximum thickness thickness of over-burden of less than 300 meters, and have been mined at the surface, or under-ground, or both. Resource estimates were not calculated for other coal beds in the Pocahontas and New River Formations, either because of insufficient data of because of the beds are too thin. Figure 8 is a generalized stratigraphic column of the coal-bearing sequence in the Crumpler quadrangle showing thickness and relative positions of the various coal beds. The Crumpler quadrangle originally contained about 498 million metric tons of coal. Approximately 326 million metric tons have been mined, or lost in mining, leaving remaining resources of 172 million metric tons. Analyses of the mined coal beds in the Crumpler and adjacent quadrangle show the coal is medium - to low volatile bituminous (most are low volatile bituminous), containing 14-27 percent volatile matter (with an arithmetic mean of 18 percent), 2.1-22.4 percent ash (with an arithmetic mean of 7 percent), and 0.5-1.8 percent total sulfur (with an arithmetic mean of 0.8 percent). Heating values range from 6,380 to 8,610 Kcal/kg on an as-received basis. Trace element and major and minor oxide composition, of both whole coal and laboratory ash, for 59 samples within or near the quadrangle were obtained from USCHEM (Geochemical Data File or National Coal Resources Data System), (Kozey and others, 1980.) Neither elements of environmental concern such as arsenic, lead, mercury, and selenium nor potentially valuable elements such as germanium, uranium and thorium were found in significant amounts in the coal.

West Virginia↗
USGS1996

Effect of surface area and chemisorbed oxygen on the SO2 adsorption capacity of activated char

The objective of this study was to determine whether activated char produced from Illinois coal could be used effectively to remove sulfur dioxide from coal combustion flue gas. Chars were prepared from a high-volatile Illinois bituminous coal under a wide range of pyrolysis and activation conditions. A novel char preparation technique was developed to prepare chars with SO2 adsorption capacities significantly greater than that of a commercial activated carbon. In general, there was no correlation between SO2 adsorption capacity and surface area. Temperature-programmed desorption (TPD) was used to determine the nature and extent of carbon-oxygen (C-O) complexes formed on the char surface. TPD data revealed that SO2 adsorption was inversely proportional to the amount of C-O complex. The formation of a stable C-O complex during char preparation may have served only to occupy carbon sites that were otherwise reactive towards SO2 adsorption. A fleeting C(O) complex formed during SO2 adsorption is postulated to be the reaction intermediate necessary for conversion of SO2 to H2SO4. Copyright ?? 1996 Elsevier Science Ltd.

Fuel↗
USGS1953

Coal resources of the United States (a progress report, October 1, 1953)

As estimated in this second progress report, the coal reserves of the United States remaining in the ground on January 1, 1953, total 1,899,739 million tons. This figure is about a 20 percent reduction of the total estimate published in the first progress report (Averitt and Berryhill, 1950). The new total is based on new, detailed, conservative estimates of reserves in Indiana, Michigan, Montana, New Mexico, North Carolina, North Dakota, South Dakota, Virginia, and Wyoming, prepared since 1947 by the U. S. Geological Survey; on new provisional, but equally conservative estimates of reserves in Colorado, Maryland, and Georgia, based on previous work of the U. S. Geological Survey and other agencies; on estimates of reserves in Illinois, Kansas, Pennsylvania, and West Virginia, prepared by the geological surveys of those States; and on older and incompletely documented estimates for the remaining states. The older estimates were prepared on a highly generalized basis and were intended to represent total possible reserves in both thick and thin beds and under both light and heavy overburden. The recent estimates have been prepared on a more conservative basis than the older estimates and tend to be considerably smaller. New conservative estimates have now been prepared for 16 coal-bearing States, which include about two-thirds of the total estimated reserves of the United States. As new estimates are prepared for the remaining States a further reduction of the total reserve figure is in prospect, though the reserves still will be large. The estimated recoverable reserves of the United States as of January 1, 1953, total 949,870 million tons, based on the assumption that half of the coal reserves in the ground will be lost in mining, and half will be recovered. The distribution of the remaining and recoverable reserves by rank is shown in the accompanying table. The reserves in 10 States have been classified in considerable detail according to thickness of beds, thickness of overburden, and relative abundance of reliable information available for making estimates. In these States, which are representative of several coal provinces, and contain about 40 percent of the total reserves, and are thus typical of the United States as a whole, 5 percent of the total is measured reserves in beds 28 inches or more thick, and less than 1,000 feet below the surface; and 20 percent is indicated reserves within the same limit of thickness and less than 2,000 feet below the surface. The remaining 75 percent is inferred reserves, reserves in thin beds, and reserves 2,000 to 3,000 feet below the surface. The large percentage of inferred reserves obviously includes some coal in thick beds, which for lack of detailed information cannot be appraised quantitatively. Although accurately based on the data now available, the distribution percentages are subject to considerable change as new work is completed, particularly in the transfer of reserves from the indicated and inferred categories to the measured category. The figures serve, however, to indicate the present state of knowledge of the Nation's coal reserves, and they point to the need for additional geologic mapping and exploration.

Circular↗
USGS1984

Hydrology of area 53, northern Great Plains and Rocky Mountain coal provinces, Colorado, Wyoming, and Utah

Hydrologic information and analysis are needed to aid in decisions to lease Federally owned coal and for the preparation of the necessary Environmental Assessments and Impact Study Reports. This need has become even more critical with the enactment of the Surface Mining Control and Reclamation Act of 1977 (Public Law 95-87). This report, one in a series of nationwide coal province reports, presents information thematically by describing single hydrologic topics through the use of brief texts and accompanying maps, graphs, or other illustrations. The report broadly characterizes the hydrology of Area 53 in northwestern Colorado, south-central Wyoming, and northeastern Utah. The report area, located primarily in the Wyoming Basin and Colorado Plateau physiographic provinces, consists of 14,650 square miles of diverse geology, topography, and climate. This diversity results in contrasting hydrologic characteristics. The two major rivers, the Yampa and the White Rivers, originate in humid granitic and basaltic mountains, then flow over sedimentary rocks underlying semiarid basins to their respective confluences with the Green River. Altitudes range from 4,800 to greater than 12,000 feet above sea level. Annual precipitation in the mountains, as much as 60 inches, is generally in the form of snow. Snowmelt produces most streamflow. Precipitation in the lower altitude sedimentary basins, ranging from 8 to 16 inches, is generally insufficient to sustain streamflow; therefore, most streams originating in the basins (where most of the streams in coal-mining areas originate) are ephemeral. Streamflow quality is best in the mountains where dissolved-solids concentrations generally are small. As streams flow across the sedimentary basins, mineral dissolution from the sedimentary rocks and irrigation water with high mineral content increase the dissolved-solids concentrations in a downstream direction. Due to the semiarid climate of the basins, soils are not adequately leached; consequently, flows in the ephemeral streams usually have larger concentrations of dissolved solids than those in perennial streams. Ground-water supplies are restricted by the low yields of wells due to small permeability. Most ground-water use is for domestic and stock-watering purposes; it is limited by the amount and type of dissolved material. The ground-water ionic composition is highly variable. Dissolved-solids concentrations for aquifers sampled in Area 53 range from a minimum of 46 milligrams per liter to a maximum of 109,000 milligrams per liter. Trace element concentrations generally are not a problem. An estimated 82 billion tons of coal exist above a depth of 6,000 feet in the Colorado parts of the area. The coal beds of greatest economic interest occur in the sedimentary deposits of the Upper Cretaceous Iles and Williams Fork Formations of the Mesaverde Group and the Upper Cretaceous Lance Formation and the Fort Union and Wasatch Formations of Tertiary age. The coal characteristically has a low sulfur content. Hydrologic problems related to surface mining are erosion, sedimentation, decline in water levels, disruption of aquifers, and degradation of water quality. Because the semiarid mine areas have very little runoff and the major streams have large buffer and dilution capacities, the effects of mining on surface water are minimal. However, effects on ground water may be much more severe and long lasting.

Colorado, Wyoming and Utah↗
USGS2018

Topics in coal geochemistry—Short course

This short course was prepared at the request of Servicio Geológico Colombiano (SGC) as a module for staff training. Prior to the short course, the SGC expressed interest in receiving training in (1) geochemistry and quality of coal; (2) geochemistry of trace elements in coal; (3) mercury and halogens in coal; (4) characterization and cycling of atmospheric mercury; (5) mercury, trace elements, and organic constituents in atmospheric fine particulate matter; (6) mercury in coal and the effect of coal quality on mercury emissions from combustion systems; (7) environmental and health effects related to coal use; and (8) related topics in coal combustion processes. A five-session short course was prepared that addressed all but the engineering aspects of coal use. In the sections that follow, topic overviews are given for the material that was presented. Brief descriptions of each slide are given in appendix 1, and the actual short course material, presented as a series of PowerPoint slides, is included in Portable Document Format (PDF) as appendix 2.

Open-File Report↗
USGS2011

Bibliography of the Gulf of Mexico coastal plain coal geology

Unlike scientific literature pertaining to most other coal-bearing regions in the conterminous United States, this bibliography on the coal geology of the Gulf Coastal Plain is dominated by work from the late 20th century. Although coals of this region were mined commercially in the late 1800s and early 1900s, they were eclipsed by the production and use of oil and gas in the middle 1920s and were not mined again as a significant fuel source until the 1970s. As a result, the literature consists mainly of a relatively small number of pre-1920 contributions in state and federal reports, followed by a plethora of technical papers, symposia proceedings, field guides, theses, dissertations, and abstracts over the past 40 years. The purpose of this chapter is to record the present work used by U.S. Geological Survey personnel preparing the Gulf Coast Coal Resource Assessment and to furnish an introduction to the larger body of sedimentary, stratigraphic, paleontologic, geochemical, hydrologic, and mining literature that exists in the region. This bibliography is an update of an earlier compilation (Tewalt et al., 1990). Despite its length, it is not exhaustive. Nor is it restricted to papers that focus solely upon coals because an understanding of these coals is rooted in the general geologic literature of the Gulf Coastal Plain.

Louisiana, Texas↗
USGS1984

MICROCHARACTERIZATION OF ARSENIC- AND SELENIUM-BEARING PYRITE IN UPPER FREEPORT COAL, INDIANA COUNTY, PENNSYLVANIA.

Optical and scanning electron microscope as well as electron and proton microprobe techniques have been used in a detailed investigation of the modes of occurrence of arsenic and selenium in pyrite in Upper Freeport coal from the Homer City area, Indiana County, Pennsylvania. Polished blocks were prepared from columnar samples of the coal bed to represent particular zones continuously from top to bottom. Initial selection of zones to be studied was based on chemical analysis of bench-channel samples. Microprobe data indicate that the highest concentrations of arsenic (as great as 1. 5 wt. %) are apparently in solid solution in pyrite within a limited stratigraphic interval of the coal bed. Smaller amounts of arsenic and selenium (concentrations up to approximately 0. 1 and 0. 2 wt. % respectively) were detected at isolated points within pyrite grains in various strata of the coal bed.

Scanning Electron Microscopy↗
USGS1954

Geology and coal deposits of the Dugger quadrangle, Sullivan County, Indiana

The accompanying maps and related material describing the geology and coal deposits of the Dugger quadrangle were prepared as part of a cooperative program to appraise the coal resources of Indiana initiated by the Division of Geology, Indiana Department of Conservation, and the Geological Survey, United States Department of the Interior. The field work on which the maps were based was done by the writer, assisted by E. D. McKay, between June 15 and August 31, 1949. The Dugger quadrangle covers nearly 58 square miles in east-central Sullivan County, Indiana, between latitude 39° and 39°07'30" N. and longitude 87°15' and 87°22'30" W. Dugger, the largest town in the quadrangle and the main shipping point, is 30 miles south of Terre Haute. The mines in the quadrangle are served by the Illinois Central, the Chicago, Milwaukee, St. Paul & Pacific, and the Pennsylvania Railroads.

Indiana↗
USGS2012

Database of the United States Coal Pellet Collection of the U.S. Geological Survey Organic Petrology Laboratory

The Organic Petrology Laboratory (OPL) of the U.S. Geological Survey (USGS) Eastern Energy Resources Science Center in Reston, Virginia, contains several thousand processed coal sample materials that were loosely organized in laboratory drawers for the past several decades. The majority of these were prepared as 1-inch-diameter particulate coal pellets (more than 6,000 pellets; one sample usually was prepared as two pellets, although some samples were prepared in as many as four pellets), which were polished and used in reflected light petrographic studies. These samples represent the work of many scientists from the 1970s to the present, most notably Ron Stanton, who managed the OPL until 2001 (see Warwick and Ruppert, 2005, for a comprehensive bibliography of Ron Stanton's work). The purpose of the project described herein was to organize and catalog the U.S. part of the petrographic sample collection into a comprehensive database (available with this report as a Microsoft Excel file) and to compile and list published studies associated with the various sample sets. Through this work, the extent of the collection is publicly documented as a resource and sample library available to other scientists and researchers working in U.S. coal basins previously studied by organic petrologists affiliated with the USGS. Other researchers may obtain samples in the OPL collection on loan at the discretion of the USGS authors listed in this report and its associated Web page.

Open-File Report↗
USGS1983

Recommended procedures and methodology of coal description

This document is the result of a workshop on coal description held for the Branch of Coal Resources of the U.S. Geological Survey in March 1982. It has been prepared to aid and encourage the field-oriented coal scientist to participate directly in petrographic coal-description activities. The objectives and past and current practices of coal description vary widely. These are briefly reviewed and illustrated with examples. Sampling approaches and techniques for collecting columnar samples of fresh coal are also discussed. The recommended procedures and methodology emphasize the fact that obtaining a good megascopic description of a coal bed is much better done in the laboratory with a binocular microscope and under good lighting conditions after the samples have been cut and quickly prepared. For better observation and cross-checking using a petrographic microscope for identification purposes, an in-place polishing procedure (requiring less than 2 min) is routinely used. Methods for using both the petrographic microscope and an automated image analysis system are also included for geologists who have access to such instruments. To describe the material characteristics of a coal bed in terms of microlithotypes or lithotypes, a new nomenclature of (V), (E), (1), (M). (S). (X 1 ). (X 2 ) and so on is used. The microscopic description of the modal composition of a megascopically observed lithologic type is expressed in terms of (VEIM); subscripts are used to denote the volume percentage of each constituent present. To describe a coal-bed profile, semiquantitative data (without microscopic study) and quantitative data (with microscopic study) are presented in ready-to-understand form. The average total composition of any thickness interval or of the entire coal bed can be plotted on a triangular diagram having V, E, and I+ M +S as the apices. The modal composition of any mixed lithologies such as (X 1 ), (X 2 ), and so on can also be plotted on such a triangular ternary diagram. Such diagrams can be used either for tracing compositional variations throughout a single coal-bed profile or for comparing variations between different coal beds.

Circular↗
USGS1997

Mechanism of SO2 removal by carbon

The reaction of SO 2 with carbon (C) in the presence of O 2 and H 2 O involves a series of reactions that leads to the formation of sulfuric acid as the final product. The rate-determining step in the overall process is the oxidation of SO 2 to SO 3 . Three SO 2 oxidation reactions are possible. Adsorbed SO 2 (C−SO 2 ) can react either with gas phase O 2 or with adsorbed oxygen (C−O complex) to form sulfur trioxide (SO 3 ), or gas phase SO 2 can react directly with the C−O complex. In optimizing the SO 2 removal capabilities of carbon, most studies only assume a given mechanism for SO 2 adsorption and conversion to H 2 SO 4 to be operable. The appropriate SO 2 oxidation step and role of the C−O complex in this mechanism remain to be determined. The ultimate goal of this study was to prepare activated char from Illinois coal with optimal properties for low-temperature (80−150°C) removal of sulfur dioxide from coal combustion flue gas. The SO 2 adsorption capacity of activated char was found to be inversely proportional to the amount of oxygen adsorbed on its surface. A temperature-programmed desorption technique was developed to titrate those sites responsible for adsorption of SO 2 and conversion to H 2 SO 4 . On the basis of these results, a mechanism for SO 2 removal by carbon was proposed. The derived rate expression showed SO 2 adsorption to be dependent only on the fundamental rate constant and concentration of carbon atoms designated as free sites. Recent studies indicate a similar relationship exists between the rate of carbon gasification (in CO 2 or H 2 O) and the number of reactive sites as determined by transient kinetics experiments. Utilizing the concept of active or free sites, it was possible to produce a char from Illinois coal having an SO 2 adsorption capacity surpassing that of a commercial catalytic activated carbon.

Energy and Fuels↗
USGS1997

Production of activated char from Illinois coal for flue gas cleanup

Activated chars were produced from Illinois coal and tested in several flue gas cleanup applications. High-activity chars that showed excellent potential for both SO 2 and NO x removal were prepared from an Illinois No. 2 bituminous coal. The SO 2 (120 °C) and NO x (25 °C) removal performance of one char compared favorably with that of a commercial activated carbon (Calgon Centaur). The NO x removal performance of the same char at 120 °C exceeded that of the Centaur carbon by more than 1 order of magnitude. Novel char preparation methods were developed including oxidation/thermal desorption and hydrogen treatments, which increased and preserved, respectively, the active sites for SO 2 and NO x adsorption. The results of combined SO 2 /NO x removal tests, however, suggest that SO 2 and NO x compete for similar adsorption sites and SO 2 seems to be more strongly adsorbed than NO. A low-activity, low-cost char was also developed for cleanup of incinerator flue gas. A three-step method involving coal preoxidation, pyrolysis, and CO 2 activation was used to produce the char from Illinois coal. Five hundred pounds of the char was tested on a slipstream of flue gas from a commercial incinerator in Germany. The char was effective in removing >97% of the dioxins and furans present in the flue gas; mercury levels were below detectable limits.

Energy and Fuels↗