Advanced physical coal cleaning to comply with potential air toxic regulations. Quarterly report, 1 March 1995--31 May 1995

Studies have indicated that the potentially hazardous trace elements found in coal have a strong affinity for coal pyrite. Thus, by maximizing the rejection of pyrite, one can minimize the trace element content of a given coal while also reducing sulfur emissions. The pyrite in most Illinois Basin coals, however, is finely disseminated within the coal matrix. Therefore, to remove the pyrite using physical coal cleaning techniques, the pyrite must be liberated by grinding the coal to ultrafine particle sizes. Fortunately, the coals being fed to pulverized coal boilers (PCB) are already ground to a very fine size, i.e., 70% passing 200 mesh. Therefore, this research project will investigate the use of advanced fine coal cleaning technologies for cleaning PCB feed as a compliance strategy. Work in this quarter has focused on the processing of a run-of-mine coal sample collected from Amax Coal Company`s Delta Coal mine using column flotation and an enhanced gravity separator as separate units and in circuitry arrangements. The {minus}60 mesh run-of-mine sample having an ash content of about 22% was cleaned to 6% while achieving a very high energy recovery of about 87% and a sulfur rejection value of 53% in a single stage column flotation operation. Enhanced gravity treatment is believed to be providing excellent total sulfur rejection values, although with inferior ash rejection for the {minus}400 mesh size fraction. The circuitry arrangement with the Falcon concentrator as the primary cleaner followed by the Packed-Column resulted in an excellent ash rejection performance, which out performed the release analysis. Trace element analyses of the samples collected from these tests will be conducted during the next report period