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2 THE RESOURCE AND ITS UTILIZATION COAL FORMATION Coal, like other fossil fuels, represents the accumulation of organic materials in sedimentary strata. Unlike oil or gas, coal does not migrate, but it undergoes in situ compaction and induration with time to form the various ranks of coal. Coal, which may contain recognizable source material, is composed chiefly of compressed and somewhat altered remains of terrestrial plants, such as wood, bark, roots (some still in the position of growth), leaves, spores, and seeds. Accumulation of in situ residues and imported debris (mostly inorganic sediment) in swamps leads to the formation of peat. Burial of the peat and subsequent alteration by pressure and heat convert the plant material to coal. With heat and pressure over geologic time, there is a continuous transformation from peat, made up of slightly modified plant fragments that have a substantial oxygen and hydrogen content, to hard black glistening anthracitic coal, which is predominantly carbon and contains little or no recognizable plant remains. The coal genetic series has been arbitrarily divided into a number of ranks referred to, from lowest to highest rank, as lignite, subbituminous, bituminous, and anthracite coals. The more obvious features of these ranks are shown in Table 1. The higher the proportion of total carbon and the lower the volatile matter, the higher the rank of the coal in the series from lignite to anthracite. For peat to undergo the transformation to coal, a series of geologic sedimentation processes must occur over time. After peat has accumulated for a period, it must be buried under mineral sediment, generally clay, silt, and sand. In time, the peat forms beds pf coal that range from a few centimeters to many meters in thickness. The coal is often interbedded with shale, sandstone, and other sedimentary rocks. A single stratigraphic sequence may include several coal beds; 117 different coal beds have been identified and named in West Virginia alone. Coal-bearing strata may include alternating marine and nonmarine beds. The coal beds are in the nonmarine parts of the section and are of brackish-water or freshwater origin, though some peat swamps received occasional marine incursions. Clay and sand that washed into the swamp while the incipient coal accumulated and other inorganic components 11
12 TABLE 1 Distinctive Features and Typical Analytical Components of Coal of Various Ranks Features a Rank Physical Appearance Characteristics Lignite Brown to brownish Poorly to moderately consolidated1 black weathers rapidly1 plant residues apparent Subbituminous Black1 dull or waxy Weathers easily1 plant residues luster faintly shown Bituminous Black1 densei Is moderately resistant to weather- brittle ing 1 plant structures visible with microscope1 burns with short blue flame Anthracite Black1 hardi usually Very hard and brittle1 burns with with glassy luster almost no smoke b Elemental Com~nents (Eercent) In-Place Dr~ and Ash-Free Basis Moisture c Carbon Hydrogen Nitrogen Oxygen Sulfura Lignite >30 <70 >5 1-1.5 >15 0.5 Subbituminous 15-30 70-75 >5 1-1.5 10-15 0.5 Bituminous 5-15 75-91 2-5.5 1-1.5 5-10 >l.O Anthracite <5 >90 <2 <l <5 0.5 asource: Gilluly et al. (1968). b The ash content is not shown because it has a wide range for all ranks of coal. cMoisture refers to water held in the pore spaces within the coal. dSulfur content, like ash, depends largely on conditions that existed during accumulation of the peat and hence is independent of rank. However, in the United States the western low-rank coals tend to contain less sulfur than the higher-rank midwestern and eastern bituminous coals. together with some remaining plant materials remain as ash when the coal is burned. Such noncombustibles lower the heating value of coal and, by increasing the waste, detract from its desirability as a fuel. Because of the inciusion of this sediment and waterborne dissolved elements, coal beds will contain all the elements found in the eroded rocks from which the sediments are derived. A coal bed could therefore contain all the naturally occurring elements. Additional elements can be introduced into the coal after burial by infiltrating groundwater, either precipitating as minerals or through ion exchange in the clays or organic matter. In terms of biogeochemical cycles, coal represents the fixation of carbon from atmospheric carbon dioxide by plant growth over extensive geologic time. The release of all this accumulated fixed carbon into the atmosphere as carbon dioxide may result in an unbalanced biogeochemical carbon cycle. In the long term, the consequences of this imbalance may be the most significant impact of coal utilization, and these are currently under study by many scientists. Other elements will
13 be mobilized to a far less dramatic level but in sufficient quantities to warrant concern. COAL USE The higher-rank coals--anthracitic and bituminous--that occur in eastern and central North America are found in Pennsylvanian-age (upper Paleozoic) rocks (about 300 million years old). Western coals are in younger Cretaceous and lower Tertiary rocks (60 million to 135 million years old), and most are lower in rank. Small tonnages of anthracite are mined in conunercial quantit~es only in Pennsylvania. Younger lignitic and subbituminous coals occur principally in Montana, Wyoming, North Dakota, and the Gulf Coast states. As shown in Figure 5, coal-bearing rocks underlie about 14 percent of the land area of the contiquous United States. According to Averitt (1975), bituminous, subbituminous, lignitic, and anthracitic coals represent 43.1, 28.1, 27.7, and 1.1 percent, respectively, of the identified U.S. coal resources in 1974. The percentage of each of the different ranks of coal currently being produced in the United States and their typical heating values are shown in Table 2. This shows that more than 90 percent of the coal produced in the United States is bituminous (Swanson et al., 1976). Coal supplied about half of the total enerqy requirements of the United States in 1940. In 1972, which was a record year in the production and consumption of energy in the United States, only 23 percent of the total production of enerqy was derived from coal, and only 19 percent of energy consumption came from coal (Averitt, 1975). Increased demand for reliable and inexpensive sources of energy and the emphasis on reducing U.S. dependence on foreign sources of fossil fuels is, however, turning the trend of coal consumption upward. The U.S. coal resources were estimated in 1974 at 3.6 trillion metric tons, an amount equivalent to 20 percent of the world's estimated total coal resources (Averitt, 1975). Geographical distribution of these reserves is shown in Figure 6 and Table 3. The 1974 estimate of the amount of coal that can be mined economically was 396 billion metric tons (U.S. Bureau of Mines, 1977). Production of coal in 1975 was estimated at 654.6 million short tons, from which the electric utilities consumed 404.7 million tons or 61.8 percent (Table 4). Brackett (1973) estimated that by the year 1980 power utilities consumption will reach about 500 million tons annually. Enerqy contained in anthracitic coals is about 1.6 times that of lignitic coals, principally because of the high moisture and oxygen contents of the low-rank coals. In coal-fired power plants, approximately 35 percent of the heat energy contained in coal is ultimately converted into electrical energy. The actual enerqy efficiency for a specific power plant depends on such factors as coal properties, plant size, and plant load. Larger plants are usually more efficient than smaller ones, but heat-conversion efficiency in power plants is not necessarily directly proportional to the plant size. Because the increasing need for electrical energy is the predominant impetus for increased coal use, the present use pattern is likely to change only in degree. The use of coal to produce synthetic fuels for
14 0 zoo 4 00 600 MILES e======e====3 IV'"\ ' I \ A '\-i j_' '\ ~ Lo w--.ololtlt b 1tum1nous (;::;:;J L19n1te ' 1so1ottd occurrence of coal of unknown extent Medium -and h19h- 1101otitt tutu mi nous A- A n U'ii'OC⢠ft' 8- 8.t v m . no ws ~ Subbolumonous ond 1o9nite (undo II.) S- Subb1tum1nous L- L19n1te FIGURE 5 Coal fields of the conterminous United States (Gluskoter et al. I 1977) ⢠the transportation and industrial sectors will increase. Coking will probably remain at the present levels. Some increase in coal use as a chemical feedstock to replace petroleum sources is anticipated but not in the immediate future. This report reflects the foregoing use pattern in concentrating on the mobilization of trace elements from electric power production. TABLE 2 Proportion of Total Production and Typical Heating Values of Coala Production Heatin2 Value Rank (percent) Btu/lb kcal/g Anthracite 0.6 12,780 7.1 Bitwninous 95.l 12,260 7.0 Subbitwninous 3.1 9,410 5.2 Lignite 1. 2 5,000 2.8 All coal 100 11,180 6.2 aSource: Swanson et al. (1976).
15 BILLIONS OF SHORT TONS 0 100 200 300 . ···,·.·.:-:<.:········ . NORTH DAKOTA .·>:::·:::·:::::::::::::::::::········ MONTANA ILLINOIS WYOMING' AL ASK Al COLORAD02 WEST VIRGINIA PENNSYLVANIA KENTUCKY NEW MEXIC02 EXPLANATION OHIO INDIANA BITUMINOUS COAL MISSOURI SUBBITUMINOUS COAL UTAH3 - ARIZONA LIGNITE KANSAS ANTHRACITE AND SEMIANTHRACITE TEXAS I SMALL RESOURCES OF LIGNITE INCLUDED ALABAMA WITH SUBBITUMINOUS COAL. 2 INCLUDES ANTHRACITE OR SEMIANTHRACITE VIRGINIA2 IN QUANTITIES TOO SMALL"TO SHOW ON SCALE OKLAHOMA OF CIAGRAM. 3 EXCLUDES COAL IN BEDS LESS THAN 4 FEET IOWA THICK. 4 INCLUDES CALIFORNIA, GEORGIA, IOAHO, WASHINGTON2 MICHIGAN, NORTH CAROLINA, AND OREGON. TENNESSEE ARKANSAS2 SOUTH DAKOTA L MARYLAND B OTHER STATES4 FIGURE 6 Remaininq identified coal resources of the United States, January 1, 1974, by states (Averitt, 1975). CHEMICAL AND MINERALOGICAL COMPOSITION It should be recoqnized that all the material leavinq the mine portal enters inte the environment in one form or another. Man's objective must be to produce the material and avoid or minimize adverse environmental effects. For example, certain trace metals applied to crops as fertilizer may have a stronq positive environmental effect,
16 TABLE 3 Total Remaining Identified Coal Resources of the United States, January 1, 1974a (billions of short tons) Bituminous Subbituminous Anthracite and State Coal Coal Lignite Semianthracite Total Alabama 13.3 2.0 15.3 Alaska 19.4 110. 7 130.l Arizona 21.2 21.2 Arkansas 1.6 0.4 0.4 2.4 Colorado 109.l 19.7 0.02 0.08 128.9 Georgia 0.02 0.02 Illinois 146 146 Indiana 32.9 32.9 Iowa 6.5 6.5 Kansas 18.7 18.7 Kentucky (eastern) 28.2 28.2 Kentucky (western) 36.l 36.l Maryland 1.2 1.2 Michigan 0.2 0.2 Missouri 31.2 31.2 Montana 2.3 176.8 112.5 291.6 New Mexico 10.8 50.6 0.004 61.4 North Carolina 0.11 0.11 North Dakota 0 350.6 350.6 Ohio 41.2 41.2 Oklahoma 7.1 7.1 Oregon 0.05 0.28 0.33 Pennsylvania 63.9 18.8 82.7 South Dakota 0 2.2 2.2 Tennessee 2.5 2.5 Texas 6.1 10.3 16.4 Utah 23.2 0.2 23.4 Virginia 9.2 0.3 9.5 Washington 1.9 4.2 0.1 0.005 6.21 West Virginia 100.2 100.2 Wyoming 12.7 123.2 135.9 b Other states 0.6 0.03 0.05 0.68 Total 747.48 485. 71 478.17 19.59 1730.95 aSource: Averitt (1975). Some figures shown in this table were rounded off to the nearest first or second decimal place and may therefore be slightly different from the original source. Dashes indicate that tonnage is too small to make a noticeable contribution and/or is included under other ranks. bincludes California, Idaho, Louisiana, and Mississippi. whereas the same trace elements emitted to the atmosphere in an uncontrolled manner could have strong negative environmental effects. The maximum amount of a particular element that might be mobilized into the environment from coal mining and use could be estimated from data on the total major, minor, and trace-element content of coal. By virtue of its origin, coal contains nearly every naturally occurring element. However, except for carbon, hydrogen, oxygen, nitrogen, sulfur, silicon, iron, aluminum, and the alkali and alkaline earth metals, most elements are present in coal in only minor or trace
17 TABLE 4 Production and Utilization of Coal in the United States, 1975a Thousands of Short Tons Percent Production 648,438 Consumption 556,301 100 Electric utilities 403,249 72.5 Coke and steel 85,987 15.5 Other manufacturers 59,783 10.8 Retail market 7,282 1.3 aProduction and consumption figures refer to bituminous and lignite coals. Production of Pennsylvania anthracite coal amounted to 6,203 million short tons in 1975, and consumption was estimated at 5,103 million short tons. Of the amount consumed, 29 percent was used by power utilities and 41.6 percent was consumed in industrial and residential heating. Data were combined from U.S. Bureau of Mines (1977). amounts. Swaine (1977) indicated that some trace elements in coal may be associated with phenolic, carboxylic, amide, and sulfhydroxyl functional groups in the organic fraction of coal. In the inorganic fraction, the trace elements are often associated with clays, silicates, carbonates, sulfides, sulfates, and other minerals. Table 5 shows the association of some trace elements with mineral matter. Layer silicate minerals (clays), quartz, and pyrite are widely distributed in coals. Kaolinite is the most common layered silicate, although montmorillonite and illite are also found. Dolomite, siderite, calcite, and aragonite are the moat common carbonate minerals. Pyritic and marcasitic crystalline forms of FeS 2 are by far the dominant sulfide minerals occurring in coals of the United States. Barite, zircon, and fluorapatite occur sporadically. The concentration of inorganic elements in a given coal deposit depends in part on the conditions that prevailed in the peat swamp in which the coal-forming material was deposited and on the subsequent genetic history of the coal seam. These conditions, especially the hydrological conditions that affected the transport of inorganic& into the swamp, varied geographically and temporally within a given peat swamp. Therefore, the concentration of inorganic elements, as both mineral matter and organically combined species, varies from one location to another in a coal bed and from one bed to another. Typical compositional values are shown in Table 6, but it should be clearly understood that any given coal seam may contain concentrations of specific elements that deviate significantly from these values. Silicon, aluminum, calcium, magnesium, sodium, potassium, iron, manganese, and titanium are the major inorganic elements of coals but generally account for <10 percent of its total elemental composition. Lignitic coals generally contain higher amounts of silicon, calcium, magnesium, and sodium than do other ranks of coal. Of the trace and
18 TABLE 5 Possible Mineral Associations of Trace Elements with Mineral Matter in Coala Element Mineral Association Arsenic Arsenopyrite (FeAsS) Barium Barite (Baso4 l Boron Illite and tourmaline (complex aluminum silicates) Cadmium Sphalerite [(Zn,Cd)S] Cobalt Linnaeite (Co 3s 4 ) Copper Chalcopyrite (CuFeS 2 l Fluorine Fluorapatite [Ca 5 (P04 l 3 CF,OH~] Lead Galena (PbS) Manganese Siderite [(Fe,Mn)C0 3 ] and calcite [(Ca,Mn)C03] Mercury Pyrite (FeS 2 l Molybdenum Molybdenite (MoS 2 ) Nickel Millerite (NiS) Phosphorus Fluorapatite [Ca5 CPo4 > 3 CF,OH)] Selenium Pyrite (FeS 2 l Strontium Goyazite group (hydrous strontium aluminum phosphates) Zinc Sphalerite (ZnS) Zirconium Zircon (ZrSi04) asource: Swaine (1977). minor elements shown in Table 6, only mercury, lead, molybdenum, arsenic, cadmium, boron, antimony, and selenium are generally richer in coal than in the average composition of the Earth's crust (Table 7). For comparison, Table 6 also shows that the estimated average inorganic- element concentrations of coal on a worldwide basis are, in general, in the range of those for U.S. coals. The concentrations of most of the elements that occur in U.S. coal were compiled by the U.S. Geological Survey from analyses of 799 samples (Swanson et al., 1976). Their compilation is extracted in Table 8. The analyses presented in Tables 7 and 8 are on a whole-coal basis. As of 1979, these analyses and similar analyses on 3700 coal samples from the United States are stored in and available from the data bank of the U.S. Geological Survey in the National Coal Resources Data System (Carter, 1976). Regional Variations and Concentration Patterns Examination of Table 8 shows the variation that occurs in the elemental compositions of coals obtained from a number of coal-production locations in the United States. Elements considered by the Panel to be
19 TABLE 6 Chemical Composition of U.S. Coalsa,b Estimated Sub- Worldwide Element Anthracite Bituminous bituminous Lignite Average Averagec Major elements (percent) Sulfur ( s) I total 0.8 2.7 0.7 1. 7 2.oa 2.0 Sulfur (S) I sulfate 0.02 0.16 0.04 0.24 0.12 Sulfur (S) I pyritic 0.35 1. 70 0. 36 0.68 1.19 Sulfur ( S) I organic 0.48 0.88 0.32 0.75 0.70 Phosphorus (P) 0.10 0.007 0.05 Silicon (Si) 2.7 2.6 2.0 4.9 2.6 2.8 Aluminum (Al) 2.0 1.4 1.0 1.6 1.4 1.0 Calcium (Ca) 0.07 0.33 0.78 1.2 0.54 1.0 Magnesium (Mg) 0.00 0.08 0.18 0.31 0.12 0.02 Sodium (Na) 0.05 0.04 0.10 0.21 0.06 0.02 Potassium (K) 0.24 0.21 0.06 0.20 0.18 0.01 Iron (Fe) 0.44 2.2 0.52 2.0 1.6 1.0 Manganese (Mn) 0.002 0.01 0.006 0.015 0.01 0.005 Titanium (Ti) 0.15 0.08 0.05 0.12 0.08 0.05 Minor and trace elements (ppm) Antimony (Sb) 0.9 1.4 0.7 0.7 1.1 3.0 Arsenic (As) 6 25 3 6 15 5.0 Barium (Ba) 100 100 300 300 150 500 Beryllium (Be) 1.5 2.0 0.7 2.0 2.0 3 Bismuth (Bi) <0.6 <0.8 <0.7 5.5 Boron (B) 10 50 70 100 50 75 Bromine (Br) 2.3 3.2 2.6 Cadmium (Cd) 0.3 1.6 0.2 1.0 1. 3 Cerium (Ce) 5.5 12.3 7.7 11.5 Cesium (Cs) 0.40 0.25 0.4 Chlorine (Cl) 255 110 207 1000 Chromium (Cr) 20 15 7 20 15 10 Cobalt (Co) 7 7 2 5 7 5 Copper (Cu) 27 22 10 20 19 15 Dysprosium (Dy) 2.7 1.4 2.2 Erbium (Er) 0.46 0.16 0.34 0.6 Europium (Eu) 0.61 0.13 0.45 0.7 Fluorine (F) 61 77 63 94 74 Gadolinium (Gd) 0.13 0.21 0.17 1.6 Gallium (Ga) 7 7 3 7 7 7 Germanium (Ge) 0.47 1.20 0. 71 5 Hafnium (Hf) 0.75 0.30 0.60 Holmium (Ho) 0.13 0.06 0.11 0.3 Iodine (I) 1.0 1.3 1.10 Lanthanum (La) 7.5 3.2 6.1 10 Lead (Pb) 10 22 5 14 16 25 Lithium (Li) 33 23 7 19 20 65 Lutetium (Lu) 0.09 0.05 0.08 0.07 Mercury (Hg) 0.15 0.20 0.12 0.16 0.18 0.012 Molybdenum (Mo) 2 3 1. 5 2 3 5 Neodymium (Nd) 50 11 37 4.7 Nickel (Ni) 20 20 5 15 15 15 Niobium (Nb) 5.4 2.7 4.5
20 TABLE 6 (continued) Estimated Sub- Worldwide Element Anthracite Bituminous bituminous Lignite Average AverageC Praseodymium (Pr) 6.1 2.7 2.7 2.2 Rubidium (Rb) 5.3 0.98 2.90 100 Samarium (Sm) o.so 0.27 0.42 1.6 Scandium (Sc) 5 3 2 5 3 5 Selenium (Se) 3.5 4.6 1.3 5.3 4.1 3 Silver (Ag) 0.17 0.26 0.20 a.so Strontium (Sr) 100 100 100 300 100 500 Tellurium (Te) 0.1 0.1 0.1 Terbium (Tb) 0.1 0.1 0.1 0.3 Thallium (Tl) 0.1 0.12 0.1 Thorium (Th) 2.3 1.2 1.9 Thulium (Tm) 0.07 0.07 0.07 Tin (Sn) 1. 7 1. 3 1.6 Tungsten (W) 2.2 3.3 2.5 Uranium (U) 1.5 1.9 1.3 2.5 1.6 1.0 Vanadium (V) 20 20 15 30 20 25 Ytterbium (Yb) 1 1 o.s 1.5 1 o.s Yttrium (Y) 10 10 5 15 10 10 Zinc (Zn) 16 53 19 30 39 50 Zirconium (Zr) 50 30 20 50 30 aGeneralized from Swanson et al. (1976). bDashes indicate no data included in source. cGeneralized from Bertine and Goldberg (1971) and U.S. Environmental Protection Agency (1975). dExcept for sulfur, the average composition of U.S. coals was calculated from the analysis of 53, "509, 183, and 54 samples of anthracite, bituminous, subbituminous, and lignite, respectively; the all-coal average is calculated from analysis of 799 samples. The average sulfur was calculated from the analysis of 38, 277, 105, and 26 samples of these coals, respectively. The all-coal average sulfur is from the analysis of 488 samples. See footnotes to Table 8 for methods used for determining mean concentrations. TABLE 7 Enrichment Factors of Trace Elements in ~oal with Respect to the Average Composition of the Earth's Crusta, Limited Enrichment Moderate Enrichment Marked Enrichment Element Enrichment Element Enrichment Element Enrichment Hg 2.25 As 8.3 Se 82 Mo 2.00 Cd 6.5 Pb 1.28 B 5.0 Sb 5.5 aRefer to coal composition in Table 6. b The average chemical composition of the Earth's crust was taken from data reported by Taylor (1964).
21 TABLE 8 ion a,b Average U.S. Coal Composition by Loca t ' Northern Rocky Appalachian Interior Gulf Great Plains Mountain ElementC Region Province Province Province Province Alaska Major elements (percent) Sulfur, total 2.3 3.9 1.9 1.2 0.6 0.2 Sulfur, sulfate 0.09 0.27 0.33 0.03 0.05 0.01 Sulfur, pyritic 1. 56 2.37 0.59 0.76 0.19 0.07 Sulfur, organic 0.74 1.25 0.96 0.37 0. 32 0.12 Nitrogen 1. 3 1.2 0.4 0.9 1.2 0.7 Silicon 2.7 2 6.6 1.4 2.5 2.9 Aluminum 1.6 0.97 2.1 0.69 1.2 1.5 Calcium 0.12 1.2 1.2 0.97 0.59 1 Magnesium 0.068 0.089 0.291 0.255 0.104 2.5 Sodium 0.032 0.035 0.732 0.182 0.102 0.018 Potassium 0.23 0.16 0.3 0.04 0.076 0.12 Iron 1.9 3.3 2.2 0.75 0.45 0.38 Manganese 0.062 0.014 0.024 0.0051 0.0036 0.0061 Titanium 0.09 0.052 0.16 0.042 0.061 0.077 Minor and trace elements (ppm) Antimony 1.2 1. 7 0.9 0.6 0.4 2.7 Arsenic 27 21 6 3 2 3 Barium 100 70 200 500 200 700 Beryllium 2 3 2 0.5 0.7 0.7 Boron 30 100 100 70 70 70 Cadmium 0.7 7.1 1. 3 0.2 <0.1 <0.2 Chromium 20 15 20 5 5 15 Cobalt 7 7 7 2 2 5 Copper 24 20.2 28 8.3 9.1 16.8 Fluorine 80 71 124 45 70 90 Gallium 7 5 10 3 3 5 Lead 15.3 55 20 5.3 5.5 5.9 Lithium 27.6 ll 28 6.0 9.2 10.1 Mercury 0.24 0.14 0.18 0.09 0.06 4.4 Molybdenum 3 5 3 2 1.5 1.5 Nickel 15 30 20 3 30 10 Niobium 5 1.5 7 5 1 3 Scandium 5 3 7 2 2 5 Selenium 4.7 4.6 7 1.0 1.6 2 Strontium 100 50 200 150 100 100 Thallium 4.9 5.2 8.3 2.7 3.6 4.4 Uranium 1.4 3.3 3.2 0.9 1.6 1.2 Vanadium 20 20 50 10 15 30 Ytterbium 1 0.7 2 0.3 0.5 1 Yttrium 10 10 20 5 5 10 Zinc 20 373 40 25.6 9.9 24 Zirconium 50 15 70 15 20 20 aSource: Swanson et al. (1976). bSulfur and nitroqen analyses are expressed on an as-received basis. Arsenic, fluorine, mercury, antimony, selenium, thorium, and uranium were determined directly on a whole-coal basis. The remaining elements were determined in the ash and are expressed on a whole-coal basis. cAverage sulfur and nitrogen calculated from analysis of 158, 90, 19, 40, 86, and 9 samples from Appalachian region, Interior province, Gulf province, Northern Great Plains province, Rocky Mountain province, and Alaska, respectively. Averages of the remainder of the elements were calculated from the analysis of 331, 143, 34, 93, 124, and 18 samples from the Appalachian region, Interior province, Gulf province, Northern Great Plains province, Rocky Mountain province, and Alaska, respectively.
22 of qreatest concern (arsenic, boron, cadmium, fluorine, lead, mercury, molybdenum, and selenium) ranqe in averaqe concentration in coals from the reqional hiqhs and lows shown in Table 9. Table 8 also shows larqe variations in the concentrations of those elements considered to be of moderate concern (chromium, vanadium, copper, zinc, and nickel) amonq coals from those reqions. These data demonstrate the necessity of usinq the site-specific approach in assessinq health-related hazards associated with trace elements in coal resource development in the United States. Gluskoter et al. (1976, 1977), at the Illinois State Geoloqical Survey, have conducted a study that further defines the patterns of variability of trace-element concentrations within coal. They found that those elements with the qreatest variability are associated with sulfide minerals in coal. Elements that occur in orqanic combinations or that are contained within the silicate minerals have the narrowest ranqes of concentrations. Elemental concentrations tend to be hiqher in eastern coals, lower in western coals, and intermediate in the Interior coal province. The concentrations of many trace elements are positively correlated with each other in their occurrence. The hiqhest correlation was between zinc and cadmium concentrations. The concentrations of chalcophile elements (antimony, arsenic, cobalt, lead, and nickel) are also mutually correlated, as are calcium with manqanese and sodium with chlorine. The Gluskoter study consistently found the selenium content of coal to be enriched compared with the averaqe for the earth's crust. In earlier work at the Illinois State Geoloqical Survey by Ruch et al. (1974), it was found that certain of the elements (iron, beryllium, boron, chromium, copper, nickel, selenium, and vanadium) display a relatively normal distribution of concentration amonq samples; others (cadmium, zinc, arsenic, antimony, lead, tin, and mercury) exhibit a skewed and wide ranqe of concentrations. The qeochemical relations and associations of trace elements in coal have also been reviewed by Zubovic (1976). The variability in coal composition is larqe, and the mobilization from its use will larqely depend on the coal, mininq methods, type of transport (rail, barqe, pipeline, or truck), and enerqy or industrial conversion process. Any harmful consequence of the mobilization will be TABLE 9 Highest and Lowest Concentration (and Region) of the Elements of Greatest Concern to the Panela Low Hi2h Concen- Concen- Element tr a ti on Province tration Province Arsenic 2 Rocky Mountain 27 Appalachian Boron 30 Appalachian 100 Gulf and Interior Cadmium <0.2 Alaska 7.1 Interior Lead 5.3 Northern Great Plains 55 Interior Mercury 0.06 Rocky Mountain 4.4 Alaska Molybdenum 1.5 Rocky Mountain and Alaska 5 Interior Selenium 1 Northern Great Plains 4.7 Appalachian asource: Table B.
23 dependent on the environment into which the elements are released. In this analysis, all possibilities cannot be considered, and an attempt has been made to.look at the problem "on the average" as well as a few specific problems. Uranium in Coal Uranium is present in most coal in about the same very small amounts as it is in moat rocks and soils the world over--a few parts per million. Such concentrations that apply to approximately 97 percent of the coal mined and burned in the United States (Swanson et al., 1976) are based on many thousands of analyses for uranium in coal throughout the country. Therefore, rather than be improperly cited as a major or specific cause for environmental concern, uranium in coal should be clearly relegated to a category of minimal concern (Farmer et al., 1977; Peyton, 1976; Stanford Research Institute, 1977). What little uranium there is in most coal is almost entirely concentrated in the bottom ash during combustion. It is not volatilized1 rather, as an exceptionally heavy element, it reacts chemically and physically as a refractory element. The uranium, which is disseminated in the coal, becomes firmly bound in the glassy ash and is released only in very long-term reaction with natural waters. It is released from the stacked or buried ash in the same extremely minor amounts that are slowly released and dissolved from most soils and unconsolidated sediments. The relatively minor amount of uranium that is in the fly ash (generally <0.0002 percent, or <2 ppm), which is produced as particulate exhaust from a combustion plant, is so small that it can be considered as actually diluting the uranium content of the soil or other surface material on which it comes to rest. Coal in only two areas of the United States is known to contain abnormally high amounts of uranium. That in the north-central Midcontinent is high-sulfur bituminous coal of Pennsylvanian age, used principally in a few relatively small electricity-generation plants in Missouri and southern Iowa. That in the second area is spottily distributed uraniferous lignite near the northwestern corner of South Dakota. Thia lignite is a very high-ash low-Btu lignite of Paleocene age that is not now of economic value. The lignite was strip mined locally for uranium in 1957-19621 the uranium was concentrated in the ash by spreading the lignite on the ground and waste-burning the combustible fraction. The uranium content of the north-central Midcontinent bituminous coal is generally 10 to 15 ppm1 the sparsely distributed "uranium lignite" of South Dakota rarely contains more than 100 ppm. To release and recover the uranium from the ash of the combusted coal in both areas would require the pulverization of the ash, followed by treatment with strong acid and alkali chemicals, a process that is far too expensive (equipment- and labor-intensive) to be considered economical even with current market values of $30 to $40 per pound of U30e⢠As for each of the many trace elements that are potentially dangerous to health, no matter how they may be artificially released to the environment, the uranium content of coal and other disturbed rock
24 units at each planned coal mine should be precisely determined. For those few mines and coal-usinq plants where uranium content of the coal is as much as three times above that of the Earth's averaqe of about 2 ppm, special investiqations should be required to define the rates, amounts, routes of travel, and lonq-term residence sites of such uranium. Relatively little is known about the many so-called radionuclides in coal, althouqh some have various deqrees of volatility, and some are associated with or are decay products of uranium. It is known, however, that durinq coal usaqe radionuclide& are produced in almost infinitesimal amounts, barely detectible with modern mass-spectroqraphic instruments. The several existinq reports on radionuclides in coal are cited in this report, and the minimal information and the need for additional work are clearly specified in the report. ANALYTICAL PROCEDURES AND AVAILABLE STANDARDS FOR COAL AND COAL-RESIDUE ANALYSIS In recent years, qeneral interest in chemical analysis of coal and coal- related materials has siqnificantly increased to the state where adequate analytic procedures and suitable standards are currently available for many trace elements. This proqress has been possible only because many qovernmental and private laboratories made a concerted, cooperative effort based on anticipated needs of the coal industry. The number of complete modern analyses for trace elements in coal has increased qreatly in recent years. As of 1979, the larqest accumulation of these data, on 3700 samples of U.S. coal, is publicly available from the data bank of the U.S. Geoloqical Survey in its National Coal Resources Data System (Carter, 1976). Although much proqress on chemical analysis of coal has occurred in recent years, much remains to be accomplished on such coal-related materials as conversion products, intermediates, and wastes. Chemical Procedures over the years a host of techniques has evolved for determininq trace elements in coal, coke, and coal ash. More recently, the trend has been to develop instrumental techniques, in preference to chemical, colorimetric, or "wet" techniques, because these procedures tend to be faster, less tedious, and qenerally yield acceptable results when sufficiently checked. Several comprehensive reviews and bibliographies (Averitt et al., 1972, 19761 Freedman and Sharkey, 19721 Gluskoter et al., 19801 Iqnasiak et al., 19751 Konieczynski, 1969) detail the available literature. Perhaps the best quide to the determination of specific elements in coal is the bi-yearly application review on "Solid and Gaseous Fuel" (Hattman et al., 1977). Recent symposia of the American Chemical Society Fuel Division have dealt with the analysis of coal for trace elements (Babu, 19751 American Chemical Society, 1977a). Several orqanizations have published individual summaries of procedures used in their laboratories
25 (Ford et al., 1976; Gluskoter et al., 1977; Karr, 1978; Pollock, 1975; Swanson and Huffman, 1976). Coal ash and coal-related materials such as conversion wastes are also readily analyzed for trace elements by several techniques. Recent work (Sather et al., 1975) concerned with the analysis of conversion ash materials indicates that excellent agreement between two different laboratories using two or more different methods can be obtained. Mass balance studies concerned with liquefaction (Filby et al., 1976; Schultz et al., 1977) and gasification (Attari, 1973; Forney et al., 1976) processes indicate that a high level of analytical capability is available for application to these difficult matrixes, which range from dominantly organic to dominantly silicate materials. The present trend is toward development of multielemental instrumental procedures, to quantitatively cover as many elements as are applicable. Because any particular analytical discipline is better suited for certain elements than for others for various inherent reasons, a combination of methods is usually necessary to determine all elements of interest. For example, instrumental neutron activation analysis (INAA) is based on the detection of induced radioactivity. Detection is dependent on several nuclear factors and elemental concentrations relative to other possible interfering elements. For such a complex matrix as coal, coal ash, or residues, about 40 elements are currently detectable with varying degrees of acceptable accuracy and prec1s1on. Other analytical disciplines (such as optical emission and atomic absorption spectroscopy) have corresponding principles, limitations, and areas of application. The combined use of analytical disciplines thus allows overlap, enabling an approach to better accuracy. Many laboratories successfully use this approach. Table 10 lists some of the significant literature available for the determination of specific trace elements in coal and coal ash. One section lists those references concerned primarily with multielemental approaches, which include many or all of the individual elements listed. No attempt is made here to classify any method as superior to another because each, when properly developed and used, has definite inherent advantages. currently, of those listed in Table 10, the most-used methods for analyzing trace elements in coal are activation analysis, optical emission, atomic absorption, x-ray fluorescence, and mass spectrometry or combinations of these methods. In general, each of these methods is quantitatively applicable to many elements, not just for those elements listed. Mass spectrometry, unless precise and accurate isotopic dilution techniques are employed, is considered to be only semiquantitative. Most colorimetric procedures, although quantitative, are usually specific only for a particular element, hence limiting. Because of the many analytical problems incurred with complex matrixes, polarography has not been extensively developed and applied to coal analysis. Those methods generally offering lower detection limits are atomic absorption and neutron activation, usually of the order of 1 ppm or better for applicable elements. In the 1- to 10-ppm range and above, x- ray fluorescence and optical emission methods are generally useful for many elements. All of these methods are capable of acceptable precision and accuracy (e.g., ±10-15 percent of the true value) for the determination of trace elements at concentrations significantly above
TABLE 10 Literature Available for the Determination of Trace Elements in Coal and Coal Asha Multi- elemental Sb As Be B Cd Cr Cu Fe Pb Mn Hg Ni Se v Zn Th u Activation 1-12 20 37 - - - - - 67 - - 75, 76 - 87 - - 95, 96, 107 95, 96, analysis 98, 99, 107 Optical 13-19 - 38, 39 50 55-58 62 - - - - 73 - - 88 90 62 emission Atomic 20-22 - 40 51 - 63 64 - - 71 - 77-83 - - - 63 absorp- tion X-ray fluo- 23-27 - - - - - - - - - - - - 89 - - 97 97 "" 0\ rescence Mass spec- 28-30 - - 52 trometry Chemically 31 - 41-49 53, 54 59-61 - 65 66 68-70 72 74 84-86 66 - 65, 91 92-94 - 100-106 based (includes colorimetric and polaro- graphic Mixed 20, 32-36 approaches --- aNumbers are keyed to accompanying references. ⢠J
27 Table 10 (Continued) Literature Available for the Determination of Trace Elements in Coal and Coal Ash 1. K.H. Abel and L.A. Rancitelli. 1975. Major, minor, and trace element composition of coal and coal ash. In ~race Elements in Fuel, S.P. Babu, ed. Advances in Chemistry Series No. 141, American Chemical Society, Washington, o.c., pp. 118-138. 2. c. Block and R. Dams. 1975. Inorganic composition of Belgian coals and coal ashes. Environ. Sci. Technol. 9(2):146-150. 3. c. Block and R. Dams. 1973. Determination of trace elements in coal by instrumental neutron activation analysis. Anal. Chim. Acta 68(1):11-24. 4. J.K. Frost, P.M. Santoliquido, L.R. Camp, and R.R. Ruch. 1975. Trace elements in coal by neutron activation analysis with radiochemical separations. In Trace Elements in Fuel, S.P. Babu, ed. Advances in Chemistry Series No. 141, American Chemical Society, Washington, o.c., pp. 84-97. 5. G.E. Gordon. 1971. Instrumental activation analysis of atmospheric pollutants and pollution source materials. In Proceedings Conf- 710668, Identification and Measurement of Environmental Pollutants, B. Westley, ed. National Research Council of Canada, Ottawa, pp. 138-143. 6. w.s. Lyon and J.F. Emery. 1975. Neutron activation analysis applied to the study of elements entering and leaving a coal-fired steam plant. Int. J. Environ. Anal. Chem. 4(2):125-133. 7. H.T. Millard and V.E. Swanson. 1975. Neutron activation analysis of coals using instrumental techniques. Am. Nucl. Soc. Trans. 21:108-109. 8. E. Orvini, T.E. Gills, and P.O. LaFleur. 1974. Method for determination of selenium, arsenic, zinc, cadmium, and mercury in environmental matrices by neutron activation analysis. Anal. Chem. 46:1294-1297. 9. R.A. Nadkarni. 1975. Multi-element analysis of coal and coal fly- ash standards by instrumental neutron activation analysis. Radiochem. Radioanal. Lett. 21(3-4):161-176. 10. R.R. Ruch, R.A. Cahill, J.K. Frost, L.R. Camp, and H.J. Gluskoter. 1975. Trace elements in coals of the United States determined by activation analysis and other techniques. Am. Nucl. Soc. Trans. 21:107-108. 11. o.w. Sheibley. 1975. Trace elements by instrumental neutron activation analysis for pollution monitoring. In Trace Elements in Fuel, S.P. Babu, ed. Advances in Chemistry Series No. 141, American Chemical Society, Washington, o.c., pp. 98-117. 12. W.H. Zoller. 1973. Photon activation analysis. Proceedings of 2nd Joint Conf. Sensing Environ. Pollutants, Pittsburgh, Pa., pp. 185- 189. 13. R.F. Abernethy, M.J. Peterson, and F.H. Gibson. 1969. Spectrochemical analyses of coal ash for trace elements. U.S. Bur. Mines Rep. Invest. 7281. 20 pp. 14. G.B. Dreher and J.A. Schleicher. 1975. Trace elements in coal by optical emission spectroscopy. In Trace Elements in Fuel, S.P.
28 Table 10 (Continued) Literature Available for the Determination of Trace Elements in Coal and Coal Ash Babu, ed. Advances in Chemistry Series No. 141, American Chemical Society, Washington, D.C., pp. 35-47. 15. R.L. O'Neil and N.W. Suhr. 1960. Determination of trace elements in lignite ashes. Appl. Spectrosc. 14:45-50. 16. M.J. Peterson and J.B. Zink. 1964. A semiquantitative spectrochemical method for analysis of coal ash. U.S. Bur. Mines Rep. Invest. 6496. 15 pp. 17. w. Radmacher and B. Hessling. 1959. Trace elements in coal and their spectroanalytical determination. z. Anal. Chem. 167:172-182. 18. A.C. Smith. 1958. The determination of trace elements in pulverized-fuel ash. J. Appl. Chem. (London) 8:636-645. 19. c. Luedke and G. Boldt. 1971. Spectral analytical determination of trace contents in lignite-tar pitch coke. Izv. Fiz. Inst. ANEB (At. Nauchnoeksp. Baze), Bulg. Akad. Nauk 21:109-114. 20. R.R. Ruch, H.J. Gluskoter, and N.F. Shimp. 1974. Occurrence and distribution of potentially volatile trace elements in coal: A final report. Ill. State Geol. Surv. Environ. Geol. Notes 72. 96 pp. 21. C.T. Ford, R.R. Care, and R.E. Bosshart. 1976. Preliminary evaluation of the effect of coal cleaning on trace element removal. Trace Element Program, Report 3. Bituminous Coal Research, Inc., Monroeville, Pa. 115 pp. 22. R.B. Muter and C.F. Cockrell. 1969. Determination of sodium, potassium, calcium, and magnesium in siliceous coal ash and related materials by atomic-absorption spectrophotometry. Appl. Spectrosc. 23:493-496. 23. M. Berman and s. Ergun. 1968. Analysis of mineral matter in coals by x-ray fluorescence. U.S. Bur. Mines Rep. Invest. 7124. 24. J.K. Kuhn, W.F. Barfst, and N.F. Shimp. 1975. X-ray fluorescence analysis of whole coal. In Trace Elements in Fuel, S.P. Babu, ed. Advances in Chemistry Series No. 141, American Chemical Society, Washington, o.c., pp. 66-73. 25. C.J. Sparks, Jr., O.B. Cavin, L.A. Barris, and J.C. Ogle. 1973. Simple quantitative x-ray fluorescent analysis for trace elements. In Proceedings of the Seventh Annual Coaference on Trace Substances in Environmental Health, June 12-14, 1973, D.D. Hemphill, ed. University of Missouri, Columbia, pp. 361-368. 26. P.C. Simms, F.A. Ricky, and K.A. Mueller. 1976. Trace element analysis of coal using proton induced x-ray emission. Progress on Coal-Related Research at Purdue, May 9. Purdue University, pp. 9- 12. 27. R.L. Walter, R.D. Willis, W.F. Gutknecht, and J.M. Joyce. 1974. Analysis of biological, clinical, and environmental samples using proton-induced x-ray emission. Anal. Chem. 46(7):843-855. 28. J.A. Carter, R.L. Walker, and J.R. Sites. 1975. Trace impurities in fuels by isotope dilution mass spectrometry. In Trace Elements in Fuel, S.P. Babu, ed. Advances in Chemistry Series No. 141, American Chemical Society, Washington, o.c., pp. 74-83.
29 Table 10 (Continued) Literature Available for the Determination of Trace Elements in Coal and Coal Ash 29. A.G. Sharkey, Jr., T. Kessler, and R.A. Friedel. 1975. Trace elements in coal dust by spark-source mass spectrometry. In Trace Elements in Fuel, S.P. Babu, ed. Advances in Chemistry Series No. 141, American Chemical Society, Washington, o.c., pp. 48-56. 30. R. Brown, M.L. Jacobs, and H.E. Taylor. 1972. Survey of the most recent applications of spark source mass spectrometry. Am. Lab. 4(11):29-40. 31. M. Weclewska. 1960. Polaroqraphic determination of trace metals in coal ash. Prace Glownego Inst. Gornictwa, Komun. (Katowice) Ser. B. 242, pp. 1-12. 32. N.E. Bolton, J.A. Carter, J.F. Emery, c. Feldman, w. Fulkerson, L.D. Hulett, and w.s. Lyon. 1975. Trace element mass balance around a coal-fired steam plant. In Trace Elements in Fuel, S.P. Babu, ed. Advances in Chemistry Series No. 141, American Chemical Society, Washington, D.C., pp. 175-187. 33. J.W. Kaakinen, R.M. Jorden, M.H. Lawasani, and R.E. West. 1975. Trace element behavior in a coal-fired power plant. Environ. Sci. Technol. 9(9):862-869. 34. v.s. Tikhonova, M.Yu. Fedushchak, and S.B. Kazakov. 1973. Rare and trace elements in coals of the Lvov-Volyn Basin. Geol. Geokhim. Goryuch. Iskop. 34:104-107. 35. E.N. Pollock. 1975. Trace impurities in coal by wet chemical methods. In Trace Elements in Fuel, S.P. Babu, ed. Advances in Chemistry Series No. 141, American Chemical Society, Washington, D.C., pp. 23-34. 36. H.J. Gluskoter, R.R. Ruch, W.G. Miller, R.A. Cahill, G.B. Dreher, and J.K. Kuhn. 1977. Trace elements in coal: occurrence and distribution. Ill. State Geol. Surv. Circ. 499. Urbana, Ill. 154 pp. 37. P.M. Santoliquido. 1973. Use of inorganic ion exchangers in the neutron activation determination of arsenic in coal ash. Radiochem. Radioanal. Lett. 15(6):373-377. 38. R.H. Hall and H.L. Lovell. 1958. Spectroscopic determination of arsenic in anthracite coal ashes. Anal. Chem. 30:1665-1669. 39. N.A. Kekin and V.E. Marincheva. 1970. Spectrographic determination of arsenic in coal and coke. Zavod. Lab. 36:1061-1063. 40. G.I. Spielholtz, G.C. Toralballa, and R.J. Steinberg. 1971. Determination of arsenic in coal and in insecticides by atomic absorption spectroscopy. Mikrochim. Acta 6:918-923. 41. R.F. Abernethy and F.H. Gibson. 1968. Colorimetric method for arsenic in coal. U.S. Bur. Mines. Rep. Invest. 7184. 10 pp. 42. R.G. Ault. 1961. Determination of arsenic in malting coal. J. Inst. Brewing 67(1):14-28. 43. British Standards Institute. 1960. Methods for the analysis and testing of coal and coke. BS 1016, Part 10, Arsenic in Coal and Coke.·British Standards Institute, London. 22 pp. 44. A. Crawford, J.G. Palmer, and J.H. Wood. 1958. The determination of arsenic in microgram quantities in coal and coke. Mikrochim. Acta 1958:277-294.
30 Table 10 (Continued) Literature Available for the Determination of Trace Elements in Coal and Coal Ash 45. S.R. Crook and s. Wald. 1960. The determination of arsenic in coal and coke. Fuel 39:313-322. 46. L.J. Edgcombe and H.K. Gold. 1955. Determination of arsenic in coal. Analyst 80:155-157. 47. E. Jackwerth and H.G. Kloppenburg. 1962. X-ray fluorescence spectroscopic determination of trace arsenic in conjunction with a modified gutzeit method. z. Anal. Chem. 186:428-436. 48. F.H. Kunstmann and L.B. Bodenstein. 1961. Arsenic content of South African coals. J. S. Afr. Inst. Min. Metall. 62:234-244. 49. A.O. Wilson and D.T. Lewis. 1963. Application of the uranyl salt method to the determination of arsenic by the oxygen flask technique. Analyst 88:510-515. SO. O.A. Kul'skaya and O.F. Vdovenko. 1961. Spectrochemical determination of germanium, beryllium, and scandium in coal ash. Khim. Fis. Khim. Spektral'n. Metody Issled. Rssd Redkikh Rasseyan. Elementov, Min. Geol. Okhrany Nedr. SSSR 1961:135-139. 51. J. Owens and E.S. Gladney. 1975. Determination of beryllium in environmental materials by flameless atomic-absorption spectroscopy. Atom. Absorp. Newslett. 14(4):76-77. 52. M.A. Phillips. 1973. Levels of both airborne beryllium and beryllium in coal in the Hayden power plant near Hayden, Colorado. Environ. Lett. 5(3):183-188. 53. R.F. Abernethy and E.A. Hattman. 1970. Colorimetric determination of beryllium in coal. U.S. Bur. Mines Rep. Invest. 7452. 8 pp. 54. I.V. Vasil'eva and V.A. Vekhov. 1972. Determination of beryllium in coals and coke. Met. Koksokhim 32:100-101. 55. J. Konieczynski. 1960. Spectrographic method for determination of trace amounts of boron in coals, coke, pitch, and tars. Prace Glownego Inst. Gornictwa, Komun. (Katowice) Stalinograd Ser. B, 254, pp. 1-8. 56. V.N. Kryukova, E. Shishlyannikova, and O.I. Koralis. 1975. Boron distribution in coals of the Azeisk deposit in the Irkutsk region. Geokhimiya 7:1115-1119. 57. J. Millet. 1957. Determination of boron in industrial coals. Congr. Groupe Avance. Methodes Anal. Spectrog. Prod. Met. lOe, Paris 1957. pp. 229-235A. 58. s. Skalska and S. Held. 1956. Determination of trace contents of boron in graphite, coal, coke, and carbon black by the method of spectral emission analysis. Chem. Anal. (Warsaw) 1:294-300. 59. F.J. Allan, F.S. Dundas, and D.A. Lambie. 1969. Determination of boron content of some Scottish coals and distribution of the boron between various density fractions. J. Inst. Fuel 42(336):29-30. 60. F.H. Kunstmann and J.F. Harris. 1954. Microanalytical method for the determination of boron in coal. J. Chem. Metall. Mining Soc. s. Africa 55:12-15. 61. A.E. Vasilevskaya. 1971. Use of ternary boron compounds in analytical chemistry. Tr. Inst. Miner. Resur., Akad. Nauk. Ukr. RSR 5:22-31. 62. Y. Talmi. 1974. Determination of zinc and cadmium in
31 Table 10 (Continued) Literature Available for the Determination of Trace Elements in Coal and Coal Ash environmentally based samples by the radiofrequency spectrometric source. Anal. Chem. 46(8):1005-1010. 63. H.J. Gluskoter and P.C. Lindahl. 1973. Cadmium: mode of occurrence in Illinois coals. Science 181:264-266. 64. K. Dittrich and G. Liesch. 1973. Atomic absorption spectroscopic determination of chromium in electrode-grade coke. Talanta 207:689-694. 65. N~P. Fedorovskaya and L.V. Miesserova. 1967. Determination of vanadium and chromium in solid fuel ash. Tr. Inst. Goryuch. Iskop., Min. Ugol. Prom. SSSR (Moscow) 23(3):3-7. 66. N.P. Fedorovskaya and L.V. Miesserova. 1967. Use of photometric method for determining the copper and nickel contents in solid fuel ash. Tr. Inst. Goryuch. Iskop., Min. Ugol. Prom. SSSR (Moscow) 23:7-15. 67. Yu. N. Pak and L.P. Starchik. 1974. Neutron-radiation determination of the iron content in coals. Keks Khim. 11:10-11. 68. N.P. Fedorovskaya, I.M. Kazakova, and N.L. Surina. 1967. Complexometric determination of Fe(III) in the analysis of ash from solid fuels. Tr. Inst. Goryuch. Iskop., Min. Ugol. Prom. SSSR (Moscow) 23(2):14-19. 69. P.J. Jackson. 1957. The determination of ferrous iron in P.F. ash and slags from pulverized fuel-fired boilers. J. Appl. Chem. (London) 7:605-610. 70. w. Radmacher and w. Schmitz. 1959. The chelatometric determination of iron and aluminum. Brennst. Chem. 40:161-164. 71. c. Block. 1975. Determination of lead in coal and coal ashes by flameless atomic absorption spectrometry. Anal. Chim. Acta 80(2):369-373. 72. F. Cuttitta and J.J. Warr, Jr. 1958. Retention of lead during oxidative ashing of selected naturally occurring carbonaceous substances. Geochim. Cosmochim. Acta 13:256-259. 73. F. Valeska and A. Havlova. 1959. Spectrographic determination of titanium and manganese in coal. Sb. Praci Hornickeho Ustavu Cesk. Akad. Ved. 1:182-190. 74. F.M. Kessler and L. Dockalova. 1955. The determination of manganese in coal ashes. Paliva 35:178-181. 75. H.L. Rook, T.E. Gills, and P.O. LaFleur. 1972. Method for determination of mercury in biological materials by neutron activation analysis. Anal. Chem. 44:1114-1117. 76. R.R. Ruch, H.J. Gluskoter, and E.J. Kennedy. 1971. Mercury content of Illinois coals. Ill. State Geel. Surv. Environ. Geel. Notes 43. 15 pp. 77. D.H. Anderson, J.H. Evans, J.J. Murphy, and W.W. White. 1971. Determination of mercury by a combustion technique using gold as a collector. Anal. Chem. 43(11):1511-1512. 78. B.W. Bailey and F.c. Lo. 1971. Automated method for determination of mercury. Anal. Chem. 43:1525-1526. 79. H. Heinrichs. 1975. Determination of mercury in water, rocks,
32 Table 10 (Continued) Literature Available for the Determination of Trace Elements in Coal and Coal Ash coal, and petroleum with flameless atomic absorption spectrophotometry. z. Anal. Chem. 273(3):197-201. 80. c. Huffman, Jr., R.L. Rahill, V.E. Shaw, and D.R. Norton. 1972. Determination of mercury in geologic materials by flameless atomic absorption spectrometry. U.S. Geol. Surv. Prof. Paper 880-C, pp. 203-207. 81. G.W. Kalb. 1975. Total mercury mass balance at a coal-fired steam plant. In Trace Elements in Fuel, S.P. Babu, ed. Advances in Chemistry Series No. 141, American Chemical Society, Washington, o.c., pp. 154-174. 82. T.C. Rains and o. Menis. 1972. Determination of sub-microgram amounts of mercury in standard reference materials by flameless atomic-absorption spectrometry. J. Assoc. Off. Anal. Chem. 55(6):1339-1344. 83. D. Siemer and R. Woodriff. 1974. Application of the carbon rod atomizer to the determination of mercury in the gaseous products of oxygen combustion of solid samples. Anal. Chem. 46(4):597-598. 84. M.K. Pakter. 1968. Determination of mercury in coke-chemical products. Koks Khim. 7:43-46. 85. A.E. Vasilevskaya and V.P. Shcherbakov. 1963. Determination of mercury compounds in coal. Dopovidi Akad. Nauk Ukr. RSR. pp. 1494-1496. 86. A.E. Vasilevskaya, V.P. Shcherbakov, and V.I. Klimenchuk. 1962. Determination of mercury in coal by dithizon. Zavod. Lab. 28:415. 87. K.K.S. Pillay, c.c. Thomas, Jr., and J.W. Kaminski. 1969. Neutron activation analysis of the selenium content of fossil fuels. Trans. June 1969 Ann. Mtg., American Nuclear Society, Seattle. 88. Y. Talmi and A.W. Andren. 1974. Determination of selenium in environmental samples using gas chromatography with a microwave emission spectrometric detection system. Anal. Chem. 46(14):2122- 2126. 89. T.L. Belopolskaya and I.V. Serikov. 1969. Chemical and x-ray spectral determination of selenium in coals, lignites, and rocks rich in organic matter. Khim. Tverd. Topl. 6:73-79. 90. P. Buncak. 1963. Spectrographic estimat.ibn of vanadium in coke. Ropa Uhlie 5(5):144-149. 91. K. Sugawara, M. Tanaka, and A. Kozawa. 1955. A rapid colorimetric determination of vanadium in carbon materials. Bull. Chem. Soc. Japan 28:492-494. 92. v. Strnad. 1969. Complexometric determination of zinc in pitch coke. Sb. Pr. u.v.P. (Ustov Vyzk. Vyuziti Paliv) 14:56-61. 93. w. Thurau£ and H. Assenmacher. 1963. Photometric zinc determination in coal and related products. Brennst. Chem. 44:21- 22. 94. c. Weaver. 1967. The determination of zinc in coal. Fuel 46:407- 414. 95. Zh. Ganzorig, L. Dashzeweg, o. Otgonsuren, G. Khuukhenkhuu, I. Chadraabal, and D. Chultem. 1974. Non-destructive determination of
33 Table 10 (Continued) Literature Available for the Determination of Trace Elements in Coal and Coal Ash traces of uranium and thorium in materials of complex composition. Radiokhimiya 16(2):247-263. 96. H.G. Meyer. 1971. Non-destructive determination of uranium and thorium in geological materials by resonance neutron activation analysis. J. Radioanal. Chem. 7(1):67-69. 97. E. Donderer. 1972. Determination of hafnium, thorium and uranium by x-ray fluorescence analysis with the use of the addition method. Neues Jahrb. Mineral. Monatsh. 4:167-175. 98. D.C. Perricos and E.P. Belkas. 1969. Determination of uranium in uraniferous coal. Talanta 16(6):745-748. 99. J.N. Weaver. 1974. Rapid, instrumental neutron activation analysis for the determination of uranium in environmental matrices. Anal. Chem. 46:1292-1294. 100. N.S. Guttag and F.S. Grimaldi. 1954. Fluorimetric determination of uranium in shales, lignites, and monazites after alkali carbonate separation. Part 15. Collected Papers on Methods of Analysis for Uranium and Thorium. U.S. Geol. Surv. Bull. 1006, pp. 111-119. 101. M. Inagaki and u. Tokuga. 1959. Uranium in columns of UBE coal. Tanken 10:97-107. 102. J. Korkisch, A. Farag, and F. Hecht. 1958. A new method for the determination of uranium in phosphates, coal ash, bauxite by means of ion-exchange. z. Anal. Chem. 161:92-100. 103. B.C. Purkayastha and S.R. Saha. 1962. On the study of rare elements in minerals from Indian sources. Part I. On the estimation of submicro amount of uranium in Indian coal. Indian J. Appl. Chem. 25(1):20-23. 104. T. Schonfeld, M. Elgarhy, c. Friedmann, and J. Veselsky. 1960. Discussion and problems of fluorimetric determination of uranium. Mikrochim. Acta 56:883-897. 105. J. Szonntagh, L. Farady, and A. Janosi. 1955. Chromatographic determination of uranium in the ash of Hungarian coals. Maqy. Kem. Foly. 61:312-314. 106. c. Ujhelyi. 1955. Determination of small amounts of uranium in coal. Maqy. Kem. Foly. 61(12):437-442. 107. s. Amiel. 1962. Analytical applications of delayed neutron emission in fissionable elements. Anal. Chem. 34:1683-1692.
34 their detection limits. In practice, it is highly reconunended to employ two or more methods when possible to check accuracy. Multiple-method approaches also allow the determination of many more elements. One important aspect to be considered is that volatilization losses of certain elements occur during certain pretreatment and ashing procedures. This can be a limiting factor on what type of sample and analytical procedure may be applied. For example, instrumental neutron activation analysis can be applied to any matrix and requires no sample pretreatment. In contrast, analysis by atomic absorption or optical emission usually requires an "ash" sample, sometimes needing extensive pretreatment. For some elements the ash data cannot be related to the whole coal. Some of these problems have been evaluated for several elements (Guidoboni, 1973; Lee et al., 1977; Pollock, 1975; Ruch et al., 1974; Schultz et al., 1975; Vasil'eva and Vekhov, 1971; Vogel et al., 1976; Weaver, 1967); however, more effort is needed. Data on radioactivity in coal and coal-related materials are very limited. Low-level alpha-, beta-, and gamma-counting techniques have been used to assay radioactivity levels for uranium, thorium, potassium, and radium for various coals and lignites (Bayliss and Whaite, 1966; Heugi and Jedwab, 1966; Safonov, 1974; Sklyarenko et al., 1964). Elemental concentrations of uranium and thorium in coal and related materials have been determined by several methods, as listed in Table 10. The "before and after" contents of uranium and thorium in coal and ash from a coal-burning power plant have been determined (Kirchner et al., 1974), and the radium content of-0.6 to 4.7 pCi/g of ash in flue ash has been reported (Marquardt et al., 1970). Standards The current coal standard most used for trace-element analysis is the National Bureau of Standards Standard Reference Material (NBS SRM) 1632. An excellent standard for determining trace elements in coal ash is NBS SRM 1633. These standards, initially circulated to many laboratories by the NBS and the Environmental Protection Agency (EPA) as an extensive comparative analysis study, were further analyzed by several activation analysis laboratories, and comparative data for 33 elements are currently available (Ondov et al., 1975). Recently, NBS SRM 1632A, a replacement for 1632, and 1635 (a subbituminous coal) have been certified for various elements. Table 11 gives the certified values for these materials. Other comprehensive round-robin studies of coal samples, which are continuing long-term studies that involve the consideration of additional elements each year, are sponsored by the American Society for Testing and Materials (ASTM) DOS Committee on Coal and Coke. The International Standards Organization (ISO) TC 27 Committee on Solid Mineral Fuels also has extensive consensus data available for mercury, beryllium, cadmium, cobalt, fluorine, chromium, manganese, molybdenum, nickel, lead, strontium, and zinc. In addition to consensus data, several laboratories have determined a great number of trace elements in extensive surveys of U.S. coals (Swanson et al., 1976; Carter, 1976; Gluskoter et al., 1977). Although these data, in most instances, are not confirmed, these samples
35 TABLE 11 Trace-Element Certified Values in NBS SRM 1632, 1632A, 1633, and 1635a,b 1632 1632A 1633 1635 Element (Bituminous Coal) (Bituminous Coal) (Coal Fly Ash) (Subbituminous Coal) Al (3.07\) (0.32\) As 5.9 9.3 61 0.42 Sb (0.58) (0.14) Be (1. 5) (12) Cd 0.19 0.17 1.45 0.03 Ce (30) (3.6) Cr 20.2 34.4 131 2.5 Co (6) (6. 8) (38) (0.65) Cs ( 2. 4) Cu 18 16.5 128 3.6 Eu (0.54) (0.064) Fe 8,700 11,100 2, 390 Ga (8.49) (1.05) Pb 30 12.4 70 1.9 Mn 40 28 493 21.4 Hg 0.12 0.13 0.14 Hf (1.6) (0.29) Ni 15 19.4 98 1. 74 K (1. 72%) Rb (31) (112) Sc (6. 3) (0.63) Se 2.9 2.6 9.4 0.9 Si (3.2\) Ag (SO.I) Sr (1,380) s (1.64\) (0. 33\) Te (SO.I) Tl 0.59 (4) Th (3.0) 4.5 24 0.62 Ti (800) (1,750) (200) u 1.4 1.28 11.6 0.24 v 35 44 214 5.2 Zn 37 28 210 4.7 asource: Ondov et al. (1975). bAll values are in ppm unless otherwise indicated. Values in parentheses are informational values only. represent an excellent stockpile for potential reference materials. There is a need for more standards representing ranks of coals in addition to bituminous and subbituminous coals. Because some trace elements are in different chemical associations in subbituminous or lignite coalsi as compared with their association in bituminous coals, the chemical analysis problems might differ significantly. Sampling Considerations It is mandatory that proper sampling procedures be used to obtain a representative sample and, ultimately, the desired trace-element
36 evaluation of a particular source of coal. An excellent guideline addressing this problem has been published by the U.S. Geological Survey (USGS) (Swanson and Huffman, 1976). A time-honored procedure, published by the U.S. Bureau of Mines (Holmes, 1918), is still used by many organizations as a guide to proper sampling of coal seams. Several standards on sampling are also published by the American Society for Testing and Materials (ASTM D2234-76 and ASTM D2013-72). Some general problems and criteria to be considered seriously for the proper sampling of coal or any heterogeneous materials have been discussed in recent symposia and in the literature (American Society for Testing and Materials, 1973; Anders, 1977; LaFleur, 1976; Maienthal and Becker, 1976). Needs for General Analyses There is an ongoing need for further consensus and standardization of commonly available analytical methods so that trace-element data may be more comparable from one laboratory to another. Organizations such as ASTM, ISO, and the International Atomic Energy Agency (IAEA) are actively involved in this effort; however, it is a slow process. Besides the well-characterized NBS coal and coal-ash standards, there should be more standards avaiable for other ranks of coal. Increasingly needed are the availability of suitable standards and convenient analytical capabilities for trace-element analysis of coal- conversion products, intermediate materials (such as tars and chars), and residues. These materials pose special analytical problems, including sampling, pretreatment, and ashing. A general concerted "stockpiling" of these coal-conversion materials is urged for future round-robin studies involving analyses of samples distributed to several different laboratories. Although significant effort in trace-element characterization of coal-conversion systems is currently under way (Attari, 1973; Dreher, 1978; Filby et al., 1976; Forney et al., 1974; Sather et al., 1975; Schultz et al., 1977), much more is needed. This subject was discussed in terms of general areas of research needs by Magee et al. (1973). Several recent conferences and workshops (Ayer, 1974, 1976; U.S. Energy Research and Development Administration, 1976) discussed trace-element analysis and the need for proper sampling proc:.,edures in conversion processes in order to ensure accurate mass balances. Further research is needed on the elucidation of specific association of the mineral state of inorganically combined elements and also on the nature of the organically combined elements in coal and related materials. These questions have been addressed by several investigators (Given, 1974; Gluskoter et al., 1976; Koppenaal and Manahan, 1976; Zobovic, 1976). Analysis of Related Materials for Environmental Assessment This vast subject covers the trace-element analysis of a whole realm of related materials, such as water, coal-processing waste streams, soils, sediments, sludge, air, and biota. The analytical methodology for these - ------------
37 materials is extensive and can be referred to only in general terms here. The great number of published analytical procedures for these materials are included in Analytical Abstracts, Chemical Abstracts, Nuclear Science Abstracts, INIS Atom Index, and similar journals. Extensive status reports and reviews on specific topics, such as water analysis and food, appear biannually in Analvtical Chemistry (American Chemical Society, 1977). Similarly, reviews on a specific chemical procedure, such as nucleonics and ion-selective electrodes, appear biannually (American Chemical Society, 1978) in the same journal. A series of excellent NBS-sponsored conferences over the years has been concerned with the general status of sampling, sample handling, methodology, accuracy, available standards, significance of data, and general needs of most of these specific subjects (Kirchhoff, 1977; LaFleur, 1976; Meinke and Taylor, 1972). A recent NBS publication surveys the current literature on sampling, handling, and storage of various environmental samples (Maienthal and Becker, 1976). Similar types of standards are constantly reviewed, updated, and published by the ASTM. An ACS publication specifically addresses trace elements in the environment (Kothny, 1973). The EPA has published a compilation of recommended procedures for determining various trace elements in water and wastes (U.S. Environmental Protection Agency, 1974). The NBS, International Atomic Energy Agency (IAEA), USGS, ASTM, and other laboratories are making an effort to provide trace-element standards and consensus-data samples for a variety of environmental materials. These materials include water, air-filter deposition samples, a variety of biological materials, sediments, soils, plant materials, radioactivity standards, and rock (Flanagan, 1976; National Bureau of Standards, 1975). There is a need to fill out and to obtain consensus data for all elements under consideration in these currently available environmental standards. Although extensive data are available for some materials, other materials have data for only a few elements. One definite need is for an analytical standard as well as reliable and efficient methods for the analysis of stack gas. GENERAL HEALTH CONSIDERATIONS The possible significance to human health of trace metals mobilized during the coal fuel cycle is both obvious and obscure. Obvious because many metals are known to be highly toxic at high doses, but at the same time, complex pathways through the environment to man and the damage to health from low-level doses of multiple pollutants obscure the problem so much that it is difficult to draw conclusions about the real hazards. Pathways of exposure may be as direct as coal dust inhaled by underground coal miners or as circuitous as ingestion via bioaccumulation through the food chain. Fossil-fuel-cycle activities may mobilize metals over short distances, as in windblown coal fines lost during transportation, or over thousands of miles, as in increased concentrations of fossil-fuel-derived elements in the Greenland ice sheet, oceanic sediments, and midoceanic trade winds and at the South Pole (Dickson, 1972; Duce et al., 1975; Weiss et al., 1971; Zoller et al., 1974). Trace elements may injure directly, through toxic metabolic
38 interactions or by catalyzing the effects of other pollutants (Amdur, 1976; Nordberg, 1974). Finally, response is partially governed by individual nutritional and immunologic status (Nordberg, 1974). Except for dust and metal assays of the lungs of deceased underground coal miners, evaluation of actual metal dose resulting from a particular process of the coal-fuel cycle is not directly ascertainable for an individual. Recent modeling efforts provide a starting point for dose assessment (Baser and Morris, 1977; Klein et al., 1975; Vaughan et al., 1975). Despite the voluminous biochemical and toxicological literature on trace-metal effects, the nature and size of the human response to the chronic, extremely low levels of expected metal exposure from coal-fuel-cycle processes is, as yet, poorly understood, as are the characterizations of emissions from many processes. Because toxicity of trace elements is often related to physicochemical states, detailed emissions characterizations are an important facet of health effects assessment (Davison et al., 1974; Linton et al., 1976; Natusch and Wallace, 1974; Natusch et al., 1974). Results of studies directly bearing on occupational and public health effects of trace elements from the coal-fuel cycle are reviewed in conjunction with discussions of various industrial activities necessary for coal mining, processing, and utilization. Steam-electric plant coal combustion is generally considered responsible for most trace-element emissions attributable to the coal-fuel cycle; water emissions are well quantified from power plants but not good enough in other parts of the fuel cycle--extraction (underground and surface), preparation, transportation (unit train, barge, truck, and slurry pipeline), and coal gasification--to allow comparisons. Emissions for 11 trace elements to air and water from extraction, preparation, transportation, and utilization for the five major coal regions of the country in 1975 are given in Appendixes A-C. These calculations may be useful in assessing possible areas of concern to public health regionally for steps that have particularly poorly characterized emissions, such as transportation, and for making interregional comparisons. The method of computation, described in Appendix c, should be consulted before interpreting the emissions tables and appendixes. Water emissions were not considered in the summary of calculations, because the water-emissions data are too scanty for comparative purposes.
