Engineering development of advanced physical fine coal cleaning for premium fuel applications. Quarterly technical progress report 14, January--March 1996

The primary goal of this project is the engineering development of two advanced physical fine coal cleaning processes, column flotation and selective agglomeration, for premium fuel applications. The project scope includes laboratory research and bench-scale testing on six coals to optimize these processes, followed by the design, construction, and operation of a 2-t/hr process development unit (PDU). The project began in October, 1992, and is scheduled for completion by June 1997. During Quarter 14 (January--March 1996), parametric testing of the 30-inch Microcel{trademark} flotation column at the Lady Dunn Plant continued under Subtask 3.2. Subtask 3. 3 testing, investigating a novel Hydrophobic Dewatering process (HD), continued this quarter with parametric testing of the batch dewatering unit. Coal product moistures of 3 to 12 percent were achieved, with higher percent solids slurry feeds resulting in lower product moistures. For a given percent solids feed, the product moisture decreased with increasing butane to dry coal ratios. Stirring time, stirring rate, and settling time were all found to have little effect on the final moisture content. Continuing Subtask 6.4 work, investigating coal-water-fuel slurry formulation for coals cleaned by selective agglomeration, indicated that pH adjustment to 10 resulted in marginally better (lower viscosity) slurries for one of the two coals tested. Subtask 6.5 agglomeration bench-scale testing results indicate that the new Taggart coal requires a grind with a d{sub 80} of approximately 33 microns to achieve the 1 lb ash/MBtu product quality specification. Also under Subtask 6.5, reductions in the various trace element concentrations accomplished during selective agglomeration were determined. Work was essentially completed on the detailed design of the PDU selective agglomeration module under Task 7 with the issuing of a draft report