Abstract |
The report reviews existing reports and data on the occurrence of sulfur and trace elements in U.S. coals and on the effect of coal properties on trace element partitioning during coal use. Emphasis was on: (1) the effect of depositional conditions on the formation and composition of mineral matter in coal, (2) the elemental concentration of major and trace elements in U.S. coals as a function of rank and geographic location, (3) analytical methods used for evaluating the modes of occurrence of these elements in coal, (4) conceptual models for predicting sulfur and trace element occurrence as a function of depositional conditions and chemical equilibrium, and (5) the fate of major and trace elements during coal cleaning, combution, gasification, and waste disposal. Coal washability data for 44 U.S. coal samples were used to statistically estimate the trace element reduction potential for a coal as a function of sulfur and ash reduction. Data fits were especially good for elements associated with the clay minerals, and to a lesser extent with the sulfides. Coal combustion data from 15 previous studies at commercial power plants were also analyzed; but, due to differences in technological processes at various plants, possible analytical errors, and limited data, statistical correlations are uncertain. |