Washability and analytical evaluation of potential pollution from trace elements in coal

Abstract

This report presents the results of a washability study showing the trace element contents of various specific gravity fractions for 10 coal samples collected from various coal-producing regions of the United States. Reliable analytical methods were developed to determine cadmium, chromium, copper, fluorine, mercury, manganese, nickel, and lead in the whole coals and the various specific gravity fractions of the coals. The material balances for the 8 trace elements for the 10 coals ranged from 85 to 115 percent with an average of 99 percent and a 95-percent confidence interval of +-3 percent. The magnitude of the concentrations of the various trace elements varied quite a bit from coalbed to coalbed within a region and also from region to region. The data from the analytical determinations on the washed coals are plotted as washability curves so that the quantity and quality of the clean coal products can be obtained at the desired specific gravity of separation. Generally, the data showed that most of the trace elements of interest concentrated in the heavier specific gravity fractions of the coal, indicating that they are associated with mineral matter; removal of this material should result in significant trace element reductions, ranging up tomore » 88 percent. A list of references of other studies of trace elements in coal is presented.« less

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