Marketable products from gypsum, a coal combustion byproduct derived from a wet flue gas desulfurization process
For two years the authors have been developing a process to produce two marketable products, ammonium sulfate fertilizer and precipitated calcium carbonate (PCC), from wet limestone flue gas desulfurization (FGD) by-product gypsum. Phase I of the project focused on the process for converting FGD-gypsum to ammonium sulfate fertilizer with PCC produced as a by-product during the conversion. Early cost estimates suggested that the process was economically feasible when granular size ammonium sulfate crystals were produced. However, sale of the by-product PCC for high-value commercial application could further improve the economics of the process. The results of our evaluation of the market potential of the PCC by-product are reported in this paper. The most significant attributes of carbonate fillers that determine their usefulness in industry are particle size (i.e. fineness) and shape, whiteness (brightness), and mineralogical and chemical purity. The PCC produced from the FGD gypsum obtained from the Abbott Power Plant at the University of Illinois Urbana-Champaign campus are pure calcite with a CaCO{sub 3} content greater than 98%, 3% higher than the minimum requirement of 95%. However, the size, shape, and brightness of the PCC particles are suitable only for certain applications. Impurities in the gypsum from Abbott power plant influence the whiteness of the PCC products. Test results suggested that, to obtain gypsum that is pure enough to produce a high whiteness PCC for high value commercial applications, limestone with minimum color impurities should be used during the FGD process. Alternatively, purification procedures to obtain the desired whiteness of the FGD-gypsum can be used. Further improvement in the overall qualities of the PCC products should lead to a product that is adequate for high-value paper applications.
- Research Organization:
- Coal and Slurry Technology Association, Washington, DC (United States)
- OSTI ID:
- 585301
- Report Number(s):
- CONF-980309--PROC.
- Country of Publication:
- United States
- Language:
- English
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