Analysis of mineral constituents, sulfur forms, and beneficiation potential of coal using electron beam microanalysis

Advanced Fuel Research, Inc. has developed an instrument and the methodology for automated analysis of the mineral constituents and sulfur forms in fine coals. In addition to the amounts of the mineral present, the method determines the spatial distributions of these minerals and sulfur within the sample, allowing predictions of the beneficiation potential of the coal. The method uses an electron beam to excite x-rays of the mineral elements from a larger number of subsamples of the coal, where a subsample is small compared to the coal particle size. From the spatial distribution of these x-ray intensities, the organic and mineral sulfur contributions can be identified, and from the mineral distributions the distribution of coal particle densities can be calculated. Thus, a prediction can be made of the fraction of the coal that will sink at a given fluid density, if ground to the subsample size. This prediction can then be combined with the coal particle size distribution to predict washability curves. The analysis requires about 10 minutes of sample preparation plus an additional 10 minutes of analysis time for each subsample size of interest. The method yields quantitative predictions of all the mineral concentrations (including sulfur) in all densitymore » fractions.« less