Chemical composition of macerals in bituminous coals of the Gunnedah Basin, Australia, using electron microprobe analysis techniques

The chemical composition of the organic matter in the principal macerals of high-volatile bituminous coals from the Gunnedah Basin, New South Wales (R v(max) of telocollinite between 0.6 and 1.1%) has been evaluated from polis hed section specimens using an electron microprobe technique. Highest propo rtions of carbon occur in the inertinite macerals, especially fusinite and secretinite (formerly resino-sclerotinite), as well as in sporinite; lowest proportions of carbon occur in the different macerals of the vitrinite gro up. Oxygen shows the reverse trend, being most abundant in vitrinite and le ast abundant in the inertinite components, whereas sulphur is lowest in the inertinites and highest in the liptinite (mainly sporinite) present. Evalu ations of maceral composition, using the carbon content of telocollinite as a rank indicator, show that carbon is more abundant in both sporinite and semifusinite, relative to vitrinite, in low-rank high-volatile bituminous c oals. The difference decreases with increasing rank, and the proportion of carbon in telocollinite becomes essentially the same as that in sporinite a nd semifusinite at carbon contents of about 89 and 91%, respectively. The c arbon content of fusinite and secretinite, on the other hand, does not seem to vary appreciably with rank advance. No significant difference in compos ition occurs in the rank range studied between the three vitrinite varietie s present, desmocollinite, telocollinite and a more highly reflecting teloc ollinite resembling pseudovitrinite. No evidence was found to indicate a hi gher hydrogen content, relative to telocollinite, for the vitrinite matrix of desmocollinite. (C) 1999 Elsevier Science B.V. All rights reserved.