Ultrafine structure of coal determined by electron microscopy
The present paper is one of a series in which electron microscope analyses including transmission, scanning transmission, and scanning reflection methods have been employed in examining bituminous coals. These techniques have the advantage of revealing the microstructures of coal at magnifications substantially greater than that available with light microscopy. Consequently, a more detailed direct observation of the pores and submicron minerals within the coal may be obtained. The shape and size of pores in two high volatile bitumous coals of differing lithotypes have been directly observed by means of transmission electron microscopy (TEM). The distribution of the porosity with respect to their maceral associations were ascertained as were the sizes and distributions of the micro minerals. The use of stereo pairs reveals the interconnectivity of the pores in micro volumes of the macerals indicating a high degree of permeability within those regions. The finest porosity was observed in vitrinite fragments of both coals and ranged in size from under 2 nm to 20 nm in diameter, with the majority in the smaller end of the size range. On the other hand, inertinite appears to be the most porous maceral and typically contains a broad range of pores from 5 through 50 nm. Much of the inertinite is granular material varying from fine to coarse grained particles with the former corresponding to micrinite. Finally, the least porous maceral is exinite which generally appears as a featureless material except for the presence of irregular and tubular pores thought to be initiated by the catalytic action of minerals. The intimate relationship between exinite and inertinite, such as exists in durains where the inertinite contains large amounts of fine mineral matter, may therefore promote the generation of porosity in exinites.
- Research Organization:
- Oak Ridge National Labs., TN
- OSTI ID:
- 6147913
- Report Number(s):
- CONF-790415-P2
- Journal Information:
- Am. Chem. Soc., Div. Fuel Chem., Prepr.; (United States), Journal Name: Am. Chem. Soc., Div. Fuel Chem., Prepr.; (United States) Vol. 24:1; ISSN ACFPA
- Country of Publication:
- United States
- Language:
- English
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