Petrographic compositions

The reactive constituents of coal (i.e., vitrinite and exinite) (Table 13.2) soften in the temperature range 400°C-500°C (750°F-930°F) and act as the so-called binder for the inert material that does not soften, nor does it undergo subsequent contraction to the same extent as the reactive components it does, however, lose volatile matter and suffer internal structural chemical change. The role of the inert material in, for example, the coking process is to reduce the overall swelling and/or contraction. 

The phenolic hydroxyl content of bituminous vitrains drops sharply to low values when the coal is heated to 450°C-500°C (840°F-930°F). It is also plausible to suggest that the hydroaromatic hydrogen content also drops sharply in a similar or somewhat lower temperature range. 

if the desired coke is to be produced, a compositional balance must be achieved between the reactive and inert components of the feed coal. If the coal is a caking coal, there will be a 

Vitrinite with reflectance between 0.5% and 2.0% exinite Semifusinite (reflectance less than 2.0%) 

Fusinite, micrinite vitrinite with reflectance greater than 2.0% mineral matter (shale, pyrite, etc.) 

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Three West Virginia coals were supplied by the West Virgmia Geological Survey (WVGS). The particular coals were chosen on the basis of rank, petrographic composition, and mineral matter content The coals were limited to the bituminous rank since these coals are the most amenable to the NMP solvent extraction process and are mdigenous to the Appalachian region. Some of the coal characteristics are listed in Table 2. 

Table III Petrographic Composition of the Coals Used (Mineral Matter Free Basis)...

Clarke, L. Storch, H.H., "Hydrogenation and Liquefaction of Coal, Part 2 - Effect of Petrographic Composition and Rank of Coal", Technical Paper 642, US Bureau of Mines, 1942. 

The coal studied, 78% C and 15.8% 0 daf, is derived from Carboniferous deposits from the Ziemowit mine in Poland. Its petrographic composition /% vol. dmmf/ is vitrinite, 60 exinite, 12 and inertinite, 28. 

In liquefactioni the additional properties of Importance are (a) the petrographic composition of the coal, and (b) Its oxygen content. 

Table II. Petrographic Composition of Selected layers of Upper Freeport Coal...

Table III. Petrographic Composition of Beds in the Lower Kittanning Coal Complex, %...

The Antarctic coal beds are apparently less persistent, and locally may be thicker, than many of the beds in Paleozoic coal fields of North America. It is hazardous to generalize about petrographic composition from hand specimens that are available from many of the coal beds, but one obtains the impression that dull, moderately dull, and midlustrous attrital layers are more prevalent than in Paleozoic coal of the Northern Hemisphere. Vitrain bands tend to be relatively sparse and thin fusain chips and partings generally are present and may be abundant. Many coal specimens are relatively impure, apparently owing to well-dispersed detrital mineral matter. 

Figure 5. Average petrographic composition of Seam 4 (left) and Seam 2 (right)...

Peter H. Given Whereas Tschamler and Fuks, and Peover studied more or less pure vitrinites, Mazumdar apparently worked with whole coals. Moreover, Indian coals, being from Gondwanaland strata, are most probably of very different petrographic composition compared with European and North American coals (rich in exinites and inert macerals See p. 284). Quite apart from the question whether sulfur dehydrogenation really is free of side reactions, there may well be a spread of data at any level or rank because of petrographic differences. 

Martin B. Neuworth In some prior work, which will be published, we analyzed the six coals for petrographic composition and found they contained from 73 to 87% vitrain. In the case of coal No. 1, we compared the petrographic composition of the residue with the original lignite. On the basis of these analyses we would conclude that the vitrinite, resinite, and exinite fractions will undergo depolymerization with the rupture of certain aliphatic linkages. The semifusinite, micrinite, and fusinite appear to be inert. 

Several approaches are being taken in an attempt to relate petrographic composition with combustion behavior. Figure 17 shows how R. along with FS1 and ash fusion data may be used to predict the burning rate of coals in a specific combustion type (cross-feed stoker). In general, as R and FSI increase and ash fusion temperatures decrease, coals require more grate surface to insure optimum burn-out and minimum loss of combustibles in the ash. 

L. L. Newman Dr. Mackowsky has already asked you if you related your studies on the kinetics of volatile matter release from Pennsylvania anthracites to the petrographic constituents of the coal. Can you not say in effect that the coals from the various collieries differ from each other quite significantly with respect to their petrographic composition and that identification of a coal by source may identify it petrographically to some extent How do the results of these studies relate decrepitation actually experienced in industrial operations ... 

Rollins, M. S., Cohen, A. D., and Durig, J. R. (1993). Effects of fires on the chemical and petrographic composition of peat in the Snuggedy Swamp, South Carolina. Int. J. Coal Geol. 22,101-117. 

Given, et. al. (2) have reported the molecular parameter analysis of asphaltenes obtained from coals of variable petrographic compositions based on proton NMR analysis. However,... 

Figure 4 Columnar section (measured in field), petrographic composition (from point counting), and molecular weathering ratios (from major element chemical analyses) of the Sheigra paleosol (Retallack and Mindszenty, 1994) (reproduced by permission of Society for Sedimentary Geology from J. Sedim. Res., 1994, A64, 264-281).

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