Precombustion removal of hazardous air pollutant precursors. Technical progress report, July 1, 1996--September 30, 1996

This project involves the development of an optimized, bench-scale processing circuit capable of efficiently removing trace elements from run-of-mine coals. The optimized circuit will be developed using characterization data obtained from detailed washability studies and release analyses tests conducted with several eastern U.S. coals. The optimized circuit will incorporate a variety of conventional and advanced coal cleaning processes. The coal products from the optimized circuit will be further treated with complexing agents specifically designed to extract organometallic trace elements that are difficult to remove by physical cleaning operations. Finally, innovative bioremediation schemes will be investigated as a means of controlling the release of trace elements from the process waste streams. Emphasis has been placed on the development of a processing circuit which (i) maximizes the rejection of trace elements, (ii) minimizes the production of coal fines which are costly to process and less marketable, and (iii) minimizes the downstream impacts of the process waste on the environment. During the past quarter, several key subtasks were completed. Most of the characterization tests for the Pittsburgh No. 8 coal have now been concluded. These include all activities associated with Subtasks 3.2 washability analysis, 3.3 flotation release analysis, and 3.4 SEM/image analysis. A large portion of the bench-scale test work was also completed during the past quarter for the Pittsburgh No. 8 coal under Subtask 4.1 heavy media testing. Additional bench-scale tests are underway as outlined in Subtask 4.2 froth flotation and 4.3 enhanced gravity separation. Finally, experiments conducted under Subtasks 6.1 analysis of pond toxics and 6.2 control method evaluation using samples of refuse from the Pittsburgh No. 8 seam indicate that significant reductions (up to 90%) in trace element content can be achieved through the application of microbial mats