Complementary analytical methods for evaluation of hard coal quality

A system of instrumental analysis of hard coal was established for the simultaneous determination of calorific value, ash and moisture content. The complementary interpretation of the measured results improved the accuracy of the analysis: the mean standard deviation may be lowered to about 1.0 wt% with regard to ash content, 900 kJ/kg for calorific value and 0.4 wt% for moisture content determinations. For borehole logging the spectrometric neutron-gamma, gamma-gamma and neutron activation techniques were used. The accuracy of the combined methods was in the range of 3 wt% for ash content, 1.5 MJ/kg for calorific value and 1.0 wt% for moisture, which was better than the interpretation of one logging technique only. The complementary interpretation of spectrometric data and conventional logging results provided detailed geological profiles with acceptable levels of accuracy. (author). 4 refs, 4 figs, 2 tabs