Coal Selection

HGI Hardgrove grindability index, HHV higher heating value, LHV lower heating value. 

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The raw data in the more comprehensive study (61) were conversions, determined in duplicate, when each of 104 coals selected from three geological provinces was heated with tetralin under standard conditions, together with the results of 14 commonly made analytical determinations for each coal. An early observation in this study was that when data for all 104 samples were plotted against volatile matter, a steady decrease of conversion with decreasing volatile matter was apparent. But there was a great deal of scatter (r=0.85). In any case, the formal requirements that make possible the employment of valid statistical analyses were not met by the data matrix, as evidenced by skewed and bimodal relationships between the variables the sample set was heterogeneous. ... 

The increase in accuracy afforded by a radiochemical separation is absolutely necessary in the determination by NAA of trace elements in the coals selected as standards. The fact that interferences from the coal matrix are removed by a radiochemical separation is the advantage of this method of analysis over such instrumental methods as x-ray fluorescence and emission spectroscopy. 

Sample Separation and Characterization. Three vitrinite samples (Silkstone, High Hazels, and Westfield) were obtained by hand-picking of macroscopic vitrain bands in Carboniferous coals. Selected vitrain particles were crushed to pass a B. S. 100 mesh sieve (250 y) and polished mounts were prepared. Sample purity was determined by point-counting (sample reflectivity) 500 points, giving a + 2% (by volume) accuracy (18). 

IL 6 coal, ISGS 020280, coal selected for interlaboratory comparison of mineral matter in coal (R. Finkelman, Allerton House Meeting, Urbana, IL, 1979). 

Fig. 19.3. Heat of combustion of U.S. coals selected to represent the various ranks. (Courtesy Bureau of Mines.)...

The selection of low-rank coals for these studies was based to some extent on those which had actually been tested or were candidate feedstocks for a slagging lignite gasifier in addition, an effort was made to choose samples that would represent a wide range of ash compositions and diverse geographical locations. The coals selected for these viscosity studies are listed in Table I. In view of the considerable within-seam or within-mine variability of low-rank coals, it should be understood that these coal samples are not necessarily representative of the total production of a particular mine. 

This new zeolite-catalyzed ring-shift isomerization could provide a new route to anthracene and its derivatives [Song, 1996], which are valuable chemicals in demand, from phenanthrene, which is rich in liquids from coal. Selective partial hydrogenation of phenanthrene would be needed as the first step. Possible applications of sym-OHAn include the manufacturing of anthracene (for dyestuffs and fine chemicals), anthraquinone (pulping agent), and pyromellitic dianhydride (the monomer for polyimides such as Du Pont s Kapton) [Song and Schol rt, 1993]. Fundamental research is needed to clarify the mechanisms and reaction pathways. 

Davey McKee Corporation, A Literature Review and Binder and Coal Selection for Research Studies on Coal Agglomeration , Febr. 26,1982. 

The refuse is dewatered and the medium is recovered, as in the coarse coal selection. The coal is discharged over a sieve bend and then proceeds to a centrifuge for final dewatering prior to transfer... 

Extract compositions depend on the particular coal/solvent system and on extraction conditions (Raj, 1979). For example, nonspecific solvents generally extract coal selectively and dissolve primarily waxy and resinons snbstances that, althongh derived from the original plant debris, may not be integral parts of the coal snbstance. 

Figure 17.4 shows the proximate analyses of coals selected to represent the various ranks of coal (reported on an ash-free basis). Analyses listed by coal bed, county, and state can be found in a number of publications, such as the data bank developed by the U.S. Department of Energy and the Pennsylvania State University Coal Bank, Bureau of Mines bulletins, Illinois State Geological Survey circulars, and the Argonne National Laboratory Coal Data Base (on a limited number of coal samples). 

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