Coal will be chemically cleaned using sodium hydroxide ascaustic at temperatures of 350' to 390'C, using caustic-to-coalratios of 2:1 and lower. Recent experience in 10 lb/hr kiln runshas shown that ratios in the range of 2:1 to 1:1 may cause a pastymass to form that sticks to the reactor wall and prevents heattransfer for reactants subsequently passing through the kiln. InPhase I experiments will be run that test the viscosity of lowcaustic-to-coal ratios at several temperatures to determine if aregime exists that is chemically and mechanically operable forcleaning coal. A laboratory-scale, stirred batch reactor will beconstructed for conducting tests to determine the limits ofcaustic-to-coal ratios that give good operability, as a guide forkiln runs. The product coal quality attained, sulfur, ash,volatiles content, Btu/lb, and surface area will be determined. Correlations will be developed relating reactor conditions,temperature and caustic-to-coal ratio, with product quality forcleaned coal product.Anticipated Results/Potential Commercial Applications as described by the awardee:Molten caustic leaching (MCL) is the onlyforeseeable cleaning method available for new plants to burn lowsulfur coal in compliance with the New Source PerformanceStandards. Because the economics of the present technologies arequestionable, no plan exists to commercialize MCL; new ideas areneeded. Continuous kiln tests give low sulfur product only whenhigher caustic-to-coal ratios are used. A test plan is plannedusing lower ratios that could lead to less expensive treatingconditions.
