Composition of coals

The composition of coal tar varies with the carbonization method but consists, largely, of mononuclear and polynuclear aromatic compounds and their derivatives. Coke oven tars are relatively low in aliphatic and phenolic content while low-temperature tars have much higher contents of both. 

The composition of coal ash varies widely. Calculated as oxides, the composition (percent by weight) varies as follows ... 

Knowledge of the composition of coal ash is usehil for estimating and predicting coal performance in coke making and, to a hmited extent, the folding and corrosion of heat-exchange surfaces in pidverized-coal-fired furnaces. 

The composition of coal is conveyed by representing its proximate and ultimate analysis. The former implies determination of contents of moisture, volatile matter, fixed carbon, and ash, while the latter implies total carbon, hydrogen, oxygen, nitrogen, sulfur and ash. Here, an account will be provided of the constituents of coal, moisture, volatile matter, ash, fixed carbon, and some miscellaneous components. 

Redding CE, SchoeU M, Monin JC, Durand B (1980) Hydrogen and carbon isotopic composition of coals and kerogen. In Douglas AG, Maxwell JR (eds.) Phys Chem Earth 12 711-723 Rees CE (1978) Sulphur isotope measurements using S02and SFg. Geochim Cosmochim Acta 42 383-389... 

Hitde DC, Stukel JJ Particle size distribution and chemical composition of coal tar fumes. Am Ind Hyg Assoc J 37 199-204, 1976... 

He published papers on the composition of coal, wood, charcoal, steel, pyrolusite, molybdenite, and spring waters, on the arts of purifying lead, hardening copper, and burning bricks, on the working of saltpeter and indigo, on resuscitation of patients with suspended animation, and on the porphyry industry at Elf dal, East Dalarne (54). 

A thorough understanding of the chemical and mineralogical composition of CCPs is necessary for proper management of these materials. This chapter will cover (1) the composition of coal (2) the formation of CCPs (3) the physical, chemical, and mineralogical characteristics of CCPs (4) characterization of North American fly ashes (5) hydrated minerals in fly ash/ water pastes (6) sulphur scrubbing products and (7) environmental impact of CCPs. 

Kolker, A., Finkelman, R. B., Affolter, R. H. Brownfield, M. E. 2000. The composition of coal combustion by-products examples from a Kentucky power plant. In Vories-Kimery, C. Throgmorton, D. (eds) The Use and Disposal of Coal Combustion By-Products at Coal Mines A Technical Interactive Forum. US Department of Interior, Office of Surface Mining. Alton, IL, United States and Southern Illinois University, Coal Research Center, Carbondale, IL, 15-24. 

Table II. Composition of Coal-Oil-Catalyst Paste for Coal Hydrogenation,...

The composition of coal mine explosives manufactured and used in Hungary is given in Tables 130 and 131. 

Some of the problems, such as safety in coal mines, merit a special monographic treatment which should go far beyond the scope of this volume. Therefore safety in coal mines was tackled only from the point of view of the composition of coal mine explosives. 

This excellent review of minerals in coal and the chemical composition of coals does not, as the title may suggest, limit itself to British coals. The literature of the rest of Europe and of North America is generously cited. A large section devoted to the various methods of determining the amount of mineral matter is included. There is also a section concerned with the methods of identifying mineral species in coals. 

In addition to discussing the major minerals and the elemental composition of coals, the authors discuss methods of removing impurities from coal and the effects of the impurities on several aspects of coal utilization. 

This introduction to the geochemistry of coal includes discussions of the origin and the physical and chemical structure of coal in addition to a discussion of the composition of coal. 

Swanson, V. E., Composition of Coal, Southwestern United States, U.S. 

Major, Minor, and Trace Element Composition of Coal and Fly Ash, as Determined by Instrumental Neutron Activation Analysis... 

The hazard of coal-related trace element pollution must be considered in conjunction with similar pollution from other sources. There is nothing toxicologically unique about the trace element composition of coal. It is geochemically similar to the makeup of the earths crust... 

Dr. Friedel. No. Products of the pyrolysis of coal under high temperature carbonization conditions surely must arise from degradation. The quantitative prediction of C7 alkane isomers from coal may possibly indicate a relationship in compositions of coal and petroleum. The hydrocarbons from each perhaps should be similar since both are supposedly derived from organic plants ... 

Local and regional variation in petrographic character of specific coal beds have been investigated actively for more than forty years. Roos (9) initiated comprehensive studies demonstrating that the character and quality of a coal seam change from place to place and that detailed sections were necessary for insight into the composition of coal. This important type of study has been continued and extended by several workers (3, 4, 5, 8, 10). In the Australian coals, Taylor and Wame noted that changes in microlithotype... 

Extended discussion of these speculative relationships is unwarranted until more critical information is available. The multilinear aspect of coalifi-cation described previously (3, 6) appears to be well illustrated by the Brandon woods. It seems evident that from a single plant tissue various dissimilar materials may result as products of coalification. Those described represent macerals related to the vitrinite, micrinite, and resinite maceral series. Because of the position of these materials in their respective series—i.e., only slightly metamorphosed and anatomically relatable to the woods of extant plants— their detailed study using appropriate chemical and physical methods should reveal useful information concerning the basic composition of coals of both higher and lower rank and simultaneously add to our knowledge of the coalification process. 

It will be noted Ihm there are a number of similarities in the various designs. Although several designs may be required to satisfy varying compositions of coal feed, it would appear that ultimately coal gasification processes will he fewer in number in the future, once the demonstration plants complete their tests. 

Some methane is manufactured hv the distillation of coal. Coal is a combustible nick formed from the remains of decayed vegetation. Ii is ihe only rock containing significant amounls of carbon. The elemental composition of coal varies between 60% and 95% carbon. Coal also contains hydrogen and oxygen, with small concentrations of nitrogen, chlorine, sulfur, and several metals. Coals are classified by the amount of volatile material they contain, that is. by how much of Ihe mass is vaporized when the coal is healed to about 900 C in the absence of air. Coal that contains more than 15% volatile material is called bituminous coal. Substances released from bituminous coal when it is distilled, in addition to methane, include water, carbon dioxide, ammonia, benzene, toluene, naphthalene, and anthracene In addition, the distillation also yields oils, tars, and sulfur-containing products. The non-volatile component of coal, which remains after distillation, is coke. Coke is almost pure carbon and is an excellent fuel, However, it may contain metals, such as arsenic and lead, which can he serious pollutants if ihe combustion products are released into the atmosphere. 

Samples submitted for chemical and physical analyses are collected for a variety of reasons, but the collection of each sample should always conform to certain guidelines. The application of precise techniques in sample collection helps to ensure that data from each analysis performed on the samples will be useful. For interpretations and comparisons of elemental compositions of coal beds to be valid, the samples must be collected so that they are comparably representative of the coal bed. Such interpretations and comparisons should never be based on data from different types of samples (Swanson and Huffman, 1976 Golightly and Simon, 1989). 

Swanson, V. E., and Huffman, C., Jr. 1976. Guidelines for Sample Collecting and Analytical Methods Used in the U.S. Geological Survey for Determining the Chemical Composition of Coal. U.S. Geological Survey 735. U.S. Department of the Interior, Washington, DC. 

Slagging, fouling, and clinkering difficulties have been found to correlate not only with the composition of coal ash but also with the fusibility of the coal ash (ASTM D-1857 ISO 540) insofar as ash fusibility is related to composition. The critical temperature most commonly referenced in evaluation of the properties of coal ash is the softening temperature. 

The true density (in fact, the helium density) has been correlated with the elemental composition of coal. Thus,... 

Coal reflectance (ASTM D-2798) is very useful because it indicates several important properties of coal, including determination of the maceral composition of coal, which, in turn, is helpful for the prediction of behavior in processing (Davis, 1978 Davis et al., 1991). Coal reflectance is determined by the relative degree to which a beam of polarized light is reflected from a polished coal surface that has been prepared according to a standard procedure (ASTM D-2797). Samples prepared by this practice are used for microscopical determination of the reflectance of the organic components in a polished specimen of coal (ASTM D-2798) as well as the volume percent of physical components of coal (ASTM D-2799). 

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