The variation of moisture with lithotype and of nitrogen and certain inorganics with petrography in Yallourn seam brown coal [manuscipt]

A tendency for darker lithotypes in Latrobe Valley brown coals to possess a higher bed moisture content than adjacent lighter lithotype coal has for some time been noted. Although the range of moisture values relating to this is generally limited to only a few per cent by weight, evidence exists to suggest that such apparently minor differences in bed moisture can and do exert a disproportionally large effect on the net output of large brown coal-fuelled thermal power stations. Samples taken over an 18 metre length of coal core obtained in Yallourn Open Cut show a correlation between moisture and lithotype, with the darker lithotypes tending to have the highest moisture and pale lithotype the lowest. A high degree of correlation is also evident between nitrogen and the amount of residual woody material present and between nitrogen and the concentration of calcium, magnesium and iron as soluble cationic species in the coal. As a result, it is shown that the small scale distribution of certain inorganic constituents is influenced by pétrographie structure.