Trace Elements in Coal - Modes of Ocurrence Analysis.

The objective is to provide modes of occurrence information for the CQ Inc. (CQ) effort being performed under DOE Contract entitled HAPs-Rx: Precombustion Removal of Hazardous Air Pollutant Precursors. This work attempts to provide semi-quantative date on modes of occurrence of 15 elements. Coals investigated include as-mined coals and cleaned fines from the Northern Appalachian and Southern Application, and Eastern Interior regions, and as-mined and natural fines from the Powder River Basin. Study techniques include scanning electron microscopy, electron micropole analysis, and leaching procedures. Microprobe data analysis indicate that pyrite grains in Northern Appalachian and Eastern Interior, and Powder River Basin coals and most of the pyrite grains of the Southern Appalachian coal contain low As concentrations, generally in the 100-500 ppm range. However, the Southern Appalachian coal contains some pyrite grains with much higher As contents, in excess of 4.0 wt. percent As. Micropole analyses and data from leaching experiments indicate that arsenic is primarily associated with pyrite in the bituminous coals. These techniques also indicate that Cr is primarily associated with illite. Other HAP`s elements have multiple associations.