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The overall goal of this project is to assess the technical and economic feasibility for producing fertilizer-grade ammonium sulfate from gypsum produced as part of limestone flue gas desulfurization (FGD) processes. This is the first year of a twoyear program with cooperative effort among the ISGS, the UIUC, AlliedSignal, SE-ME, Henry Fertilizer, Illinois Power Co. (IP), and Central Illinois Public Services (CIPS). In the previous quarter, chemistry of the process and process conditions have been reviewed and the information was used to set up a reactor system. The system was used to conduct several laboratory tests. FGD-gypsum produced at the Abbott power plant in Champaign, IL was used as a raw material. The scrubber, a Chiyoda Thoroughbred 121 FGD, produced a filter cake product contains 98.36% gypsum (CaSO4.2H20), and less than 0.01% calcium sulfite (CaSO,). Conversion of FGD-gypsum to ammonium sulfate were tested at temperatures between 60 to 70°C for a duration of five to six hours. A yield of up to 82% and a punty of up to 95% for the ammonium sulfate production was achieved.In this quarter, more bench-scale experiments including a mass balance analysis were conducted. Based on the weight of the ammonium sulfate produced and its theoretical yield from a total conversion of calcium sulfate feed, a yield of up to 83% and a purity of up to 99% for the ammonium sulfate production was achieved. Also, a more complete literature survey was conducted and a preliminary process flow sheet was developed. Using the flow sheet and engineering data, the economics of the process are being estimated. The cost estimates results will be reported in the next quarter. Also, any beneficial process variation to be considered and process limitations that need further research will be identified. EXECUTIVE SUMMARYProgress made under the United States Department of Energy's Clean Coal Technology program and the 1990 amendments to the Clean Air Act that mandate a 2-stage 10-million ton reduction in sulfur dioxide emissions in the United States have definitely promoted the use of FGD technologies. In addition to capital costs for equipment and operating expenses, plants burning high sulfur coal and using FGD technologies must also bear increasingly expensive landfill disposal costs for the solid waste produced. The FGD technologies would be less of a financial burden if successful commercial uses were developed for the gypsum-rich by-products of wet limestone scrubbing. Conversion of FGD-gypsum to a marketable product could be a deciding factor in the continued use of high-sulfur Illinois coals by electric utilities.The conversion of FGD-gypsum to calcium carbonate and ammonium sulfate by reacting it with COz and ammonia or by reacting it with ammonium carbonate is being studied in this program. A variation of this process could provide electric utilities a means to convert the C 0 2 and SO2 in their flue gas to useful commercial products. The fertilizer industry would also be provided with a large source of ammonium sulfa...

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