Victorian brown coal lithotypes

Victorian brown coals are thought to be largely amorphous, containing aromatic layers of single substituted benzene rings crosslinked by aliphatic chains to form a three dimensional structure. Their carbon content is quite low, varying from 60 to 70. One would therefore expect its porous system to be somewhat like that of an open structure having micropores which are randomly-oriented. In this preliminary study two samples of Yallourn ream coal were taken from the Yallourn open cut mine in the Latrobe Valley, Victoria, Australia. The samples, a pale and a medium dark lithotype, are representative of the extremes in coal types found in the Yallourn ream. 

Chemical Variation as a Function of Lithotype and Depth in Victorian Brown Coal... 

Victorian brown coal occurs in five major lithotypes distinguishable by color index and petrography. Advantage has been taken of a rare 100 m continuous core to compare and contrast chemical variations occurring as a function of lithotype classification. For many parameters there is a much greater contrast between the different lithotypes than there is across the depth profile of (nearly) identical lithotypes. Molecular parameters, such as the distributions of hydrocarbons, fatty acids, triterpenoids and pertrifluoroacetic acid oxidation products, together with gross structural parameters derived from IR and C-NMR spectroscopic data, Rock-Eval and elemental analyses and the yields of specific extractable fractions are compared. 

The monofatty acids (Ci -C 2) f om five lithotypes of Victorian brown coal and from a Sydney Basin black coal were analyzed by gas-liquid chromatography. The different profiles observed for the various lithotypes have been interpreted in terms of differences in depositional environment, while differences in rank appear to be responsible for the large differences between the brown and black coal samples. The presence of several classes of acids in these coals is reported, but of these the presence of monounsaturated and diunsaturated acids is particularly important in view of their assumed geochemical instability. 

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