Coal petrography

International Handbook of Coal Petrography, 2nd ed.. Centre National de la Recherche Scientifique, Paris, 1963. 

Careflil examination of a piece of coal shows that it is usually made up of layers or bands of different materials which upon microscopic examination are distinct entities distinguishable by optical characteristics (10—12). The study of the origin, composition, and technological appHcation of these materials is called coal petrology, whereas coal petrography involves the systematic quantification of the amounts and characteristics by microscopic study. The petrology of coal may involve either a macroscopic or microscopic scale. 

On the macroscopic scale, two coal classifications have been used humic or banded coals and sapropeflc or nonbanded coals. Stratification in the banded coals, which result from plant parts, is quite obvious the nonbanded coals, which derive from algal materials and spores, are much more uniform. The physical and chemical properties of the different layers in a piece of coal or a seam can vary significantly. Therefore the relative amounts of the layers are important in determining the overall characteristics of the mined product. Coal petrography has been widely appHed in cokemaking and is important in coal hquefaction programs. 

E. Stach and co-workers, Stach s Textbook of Coal Petrology, 3rd ed., Gebmder Bomtraeger, Berlin, Germany, 1982, 535 pp. Excellent text on coal petrography. 

Coal liquefaction, 6 765-766, 832-869 coprossing, 6 856-858 direct, 6 833-858 indirect, 6 858-867 use of steam in, 23 239-240 Coal mining, 6 744-745 Coal-oil coprocessing, 6 833, 856-857 Coal petrography, 6 706-709 Coal petrology, 6 706 Coals, ash properties of, 72 324t Coal slurry pipelines, 6 748 Coal tar... 

Polished sections and polished thin sections are prepared according to the usual techniques of coal petrography. They are mounted permanently on quadrangular pieces of transparent Lucite for location purposes. We have described elsewhere a graphical method of micro-surveying which allows an observer to locate any specific autoradiograph on nuclear emulsion plate of a given point in an opaque section (13). 

Coal Petrography. Of the 36 samples examined microscopically, approximately one-half contained gas vacuoles produced by thermal distillation of the coal. Thus, these coals that might otherwise have been referred to the rank of anthracite can be regarded as natural coke. All the samples, including those with gas vesicles, appeared to be fairly dense, with no macroscopic indication of a coke-structure development. The samples with the most advanced vacuole development appeared to be almost metallic in luster. All the coal entities normally encountered—vitrinoids, micrinoids, semifusinoids, and fusinoids— were present, whereas the exinoids and resinoids, which are difficult to identify with certainty in semianthracite or anthracite, were not positively identified in... 

Quring the past several years coal petrography has gained acceptance in certain areas of coal utilization, preparation, and mining as a useful analytical tool. The rapid evolution of this analytical technique can be attributed to the development and subsequent refinement of quantitative methods for measuring the reflectance characteristics of vitrinite in coal (8, 14, 15, 16). Mean maximum reflectance has been shown to be directly related to coal rank (14, 16). Moreover, it is known that rank is important in determining certain carbonization and chemical properties. 

Micropetrography evaluates the coal components ascertainable by microscopy. Figure 4 shows an extract of the results obtained from the combined maceral-microlithotype analysis after the International Handbook of Coal Petrography of the 15 brown coal lithotypes. 

Under the given conditions of the Rhenish brown coal deposit, an opencast mining operation, a high output and the large feed quantities required for future refining plants brown coal petrography is one out of many tesserae for quality assessment. The development of appropriate modes of determining the quality characteristics of raw brown coal is a task indispensable for the future. 

Sample Selection and Preparation. Samples were selected from two high-volatile bituminous coals, namely, Illinois No. 6 bright coal and an eastern Kentucky splint coal from Perry County. The choice of these coals was based on the desire to contrast the fine structure of coals of equal rank but of different lithotypes. For both coals the samples were obtained from limited regions of their respective coal seams. Detailed coal petrography was performed on these samples, and TEM specimens were subsequently selected from representative polished blocks. 

Arrowsmith, J.R., Rice, G.E. Hower, J.C. (1998) Documentation of carbon-rich fragments in varnish-covered rocks from central Arizona using electron microscopy and coal petrography. Science. 

Zhang Xiaomei Song Weiyuan 2006. The theoretical study on water s driving gas displacement as for double medium of coal petrography. Journal of China Coal Society 31(2) 187 190. 

The diverse nature of deposited plant and mineral matter and the burial conditions make it clear that coal is not one substance but a wide range of heterogeneous materials, each with considerably different chemical and physical properties from the others. The heterogeneity of coals can be seenonthe macroscopic and microscopic levels, and the science of classifying coals on the basis of these difference is called coal petrography. 

Indeed, the acknowledgment that the tissues of the original plants can themselves contribute to the physical structure of coal has led to the development of the area of scientific investigation known as coal petrography (Murchison, 1991). Thus, coal petrography is an investigation (with subsequent identification) of coal with the macrostructures and microstructures that are the physical structure of coal. 

ICCP. 1963. International Handbook for Coal Petrology, 2nd edn. International Conunittee for Coal Petrology, International Handbook of Coal Petrography, 1st Supplement to 2nd edn. Centre National de la Recherche Scientifique, Paris, France. 

Coal petrography (Chapter 4) has become widely used for predicting coke quality based on coal analysis and has led to a system for predicting coke stability based on petrographic entities and reflectance of coal (Schapiro and Ciray, 1960). Thus, an optimum blend of coals could be selected to produce desired coke quality. 

R.M.S. Falcon, C.P. Snyman, An Introduction to Coal Petrography Adas of Petrographic Constituents in the Bituminous Coals of Southern Africa. The Geological Society of South Africa, Johannesburg, South Africa, 1986,123 pp. 

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