Use of X-ray fluorescence spectrometry for the direct multi-element analysis of coal powders

Abstract

The evaluation of automated X-ray fluorescence (XRF) spectrometry for the elemental analysis of UK coals is described. The XRF determination of chlorine is now used for coal pricing purposes and phosphorus levels are reported routinely in order to monitor the quality of coal. The data on elemental composition which can be generated rapidly by direct XRF analysis of pressed coal powders enable values of slagging and fouling indices to be determined with acceptable accuracy. Such factors have wide application in industry for predicting the combustion characteristics of coal, including slagging and fouling propensities. The relative standard deviations for the elements chlorine, sulphur and phosphorus and the calculated slagging index and fouling factor are less than 7%. The accuracy of the method when compared to standard reference coals is acceptable with detection limits which range from 0.04 and 0.05% m/m for the major elements Al and Si, respectively, 0.01% m/m for minor elements and 0.002% m/m for the trace element phosphorus.