Analysis for sulphur in coal ash

Abstract

Highly precise and accurate sulphur analyses are required to establish material balance for sulphur in utility boilers where sulphur is present at low levels in the fly ashes. Sulphur determinations using the established methods depend on quantitative extraction of sulphur from some form of sample decomposition residuum. Errors from incomplete extractions can lead to results which are as much as 30% low. The total sample dissolution-X-ray fluorescence procedure developed in this study, yields results which have the precision and accuracy required for material balance calculations. Using this method, fly ash samples containing less than 1% sulphur can be determined with a relative standard deviation of about 3%. Most importantly, the new procedure eliminates the negative bias inherent in the established methods. It is important to note that the procedure is not applicable to the analysis of sulphur in coal, since the organic sulphur would escape detection. However, standard analysis procedures for the determination of sulphur in coal also have a relative standard deviation of about 3%.