Coals, chemical analyses

The key word in any case is representative. A laboratory analysis sample must be representative of the whole so that the final result of the chemical analysis represents the entire system that it is intended to represent. If there are variations in composition, such as with the coal example above, or at least suspected variations, small samples must be taken from all suspect locations. If results for the entire system are to be reported, these small samples are then mixed and made homogeneous to give the final sample to be tested. Such a sample is called a composite sample. In some cases, analysis on the individual samples may be more appropriate. Such samples are called selective samples. 

Kumari D. 1990. Chemical analysis of filtrate and condensate from wet-carbonized peat by gas chromatography-mass spectrometry. Inter J Coal Geol 15 63-69. 

The modern investigations of trace elements in coals were pioneered by Goldschmidt, who developed the technique of quantitative chemical analysis by optical emission spectroscopy and applied it to coal ash. In these earliest works, Goldschmidt (31) was concerned with the chemical combinations of the trace elements in coals. In addition to identifying trace elements in inorganic combinations with the minerals in coal, he postulated the presence of metal organic complexes and attributed the observed concentrations of vanadium, molybdenum, and nickel to the presence of such complexes in coal. 

The chemical analysis and the bench-scale and technical-scale testing were carried out either by standard tests or by tests under consideration for standardization by ASTM. Analytical data from these tests for the size fractions of the medium volatile coal are given in Table I. 

For accurate heat values of solid and liquid fuels calorimeter determinations are required. However, approximate heat values may be determined for most cools if the ultimate chemical analysis is known. Dulong s formula gives reasonably accurate results (within 2 to 3%) for most coals and is often used as a routine check of values determined by calorimeter ... 

Table III. Chemical Analysis and Molecular Weights of Tar Sands Bitumen, Coal Liquids, and Their Fractions...

Oxidized coal coal whose properties have been modified fundamentally as a result of chemisorptions of oxygen in the air or oxygen dissolved in ground-water. Chemisorption is a surface phenomenon rarely detectable by chemical analysis but usually detectable by petrographic examination. It reduces the affinity of coal surfaces for oil and seriously impairs coking, caking, and agglutinating properties. 

The Inorganics are a group of exchangeable cations and water soluble salts, analyzed by AA on dilute acid extracts from the coal and expressed in terms of chemical analysis on a coal basis as -... 

Palmer C. A. and Klizas S. A. (1997) The chemical analysis of Argonne premium coal samples. US Geological Survey BuUetin 2144. US Geological Survey. 

Swanson V. E., Medlin J. H., Hatch J. R., Coleman S. E., Woodruff S. D., and Hildebrand R. T. (1976) Collection, chemical analysis, and evaluation of 799 coal samples in 1975. US Geological Survey Open-File Rept. 76-468, 503p. United States Geological Survey. 

Coal A is an Appalachian (eastern U.S.) coal with 3.38% S and a specific surface of 23 cm /g (especially 0.5 to 5 mm sizes). Chemical analysis is the mean of samples from three identical replicate runs collected after 40 leaching days. The sample also has 50 mg/kg Be (Helz et al. 1987). 

ESCA. Electron spectroscopy for chemical analysis (ESCA) has been demonstrated to be effective in analyzing major elements in coal or ash surfaces having different chemical environments (65). Sulfur can be detected as the sulfide or sulfate. Carbon can be detected as graphite, carbonyl, carboxyl, or hydrocarbon. 

H. Wood, D. S. Woodruff, S. D. Hildebrand, R. T. "Collection, Chemical Analysis, and Evaluation of Coal Samples in 1975" U.S. Geol. Survey, Open-File Report 76-468, 1976. 

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