Influence of Petrographic Composition

It is generally recognized that vitrain is the most soluble constituent of any particular coal, whereas fusain is the least soluble. Indeed, early work on the liquefaction of coal by dissolution in a solvent showed that even at temperatures on the order of 400°C (750°F), fusain is, to all intents and purposes, insoluble. Under these aforementioned conditions, durain did show some response to the solvent but still did not match the solubility of vitrain. 

There are reports in which coal rank has been correlated with the extent of the catalytic Uqnefaction under batch conditions. Thus, while several of the correlations are questionable, there does appear to be a maximum with high-volatile C bituminous coal. However, the ability of coal to undergo liquefaction appears to correlate much more closely with maceral content than with coal rank. For example, vitrinite (Chapter 4) has been found to play a significant role in the liquefaction of coal and an almost linear relationship has been reported to exist between the percent conversion to liquid products and the vitrinite content. 

On the other hand, fusinite offers some resistance to the low-temperature hydrogenation process, which may not be surprising considering the nature of this particular maceral (Chapter 4). And, microscopic examination of residual material (often referred to incorrectly as unconverted material) from coal liquefaction has indicated structures characteristic of fusinite thereby offering further evidence for the comparatively low reactivity of this maceral. 

Other macerals, sporinite, resinite, and cutinite (Chapter 4), are all readily liquefied by hydrogenation while there is also evidence to indicate that the maceral micrinite may be more easily liquefied than has previously been thought possible, but some further substantiation is necessary. 

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Kleineidam, S. Riigner, H. Grathwohl, P. (1999) Influence of petrographic composition / organic matter distribution of fluvial aquifer sediments on the sorption of hydrophobic contaminants. Sedimentary Geology 129(3-4), 311-325. 

Fecko, R, Pectova, I., Ovcari, R, Cahhk, V., and Tora, B. 2005. Influence of petrographical composition on coal... 

To judge from the importance of sutured intergranular contacts, the younger Triassic and Jurassic rocks are less compacted than those of the Cambrian. Two other factors, viz. depth and petrographic composition, will also exert a notable influence, but it will be very difficult to evaluate them quantitatively without special investigations. It could... 

In keeping with the theme of this present chapter, a brief discussion of the influence of the petrographic composition of coal in relation to the technological properties of coal is warranted, although more specific reference will, as the data allow, be made to the various processes throughout the chapter. 

Solvent extraction under mild conditions has been and continnes to be actively pursued, primarily as a tool to probe the molecular properties and structure of coal and, in some instances, for conuner-cial applications. Research shows that the effectiveness of solvents for coal extraction is influenced by coal type, rank, and petrographic composition, and by the chanical nature of the solvent. 

It is established that the rank and chemistry of the parent coal strongly influence the optical textures of cokes. Several studies show that the development of anisotropy (size, shape, and intensity) during carbonization varies mainly with (1) coal rank (2) petrographic composition of the coals (3) plasticity of the parent coal (4) carbonization conditions such as rate of heating, soak time, and gas overpressure as well as (5) the nature of additives used in the coal blends. 

Brakerenko N.N., Emelyanov T.Y. Influence of oil on the petrographic composition of the physical and mechanical properties of the sand-clay soWsHEarth Sciences, 2011. No 342. C. 197-200c. 

Coal rank from the petrographic point of view is commonly expressed in terms of vitrinite reflectance which may act as an indicator that is independent of other factors (e.g., coal type or grade). Unlike other chemical parameters (e.g., carbon content, hydrogen content, volatile matter yield, and calorific value) it is not dependent on the overall composition of the coal. A number of coal properties progressively change with the advance in rank and the rank of a coal is therefore a major factor influencing its potential application. 

In contrast, specific solvents, which dissolve a large fraction of the coal, do so nonselectively. Thus, while the differing solubility of the petrographic constituents will influence the composition of coal extracts, the extracted material may resemble the insoluble residue closely and, in fact, may be virtually indistinguishable from it. Indeed, material snch as waxes and resins, unless present in phenomenally large amounts, is entirely masked by the remainder of the coal substance. The elemental compositions of the extracts as well as the properties (especially those associated with the chemical aspects of the dissolved material, e.g., magnetic and spectroscopic properties) are all almost identical with those of the original coal. 

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