Separation of Hg from Flue Gas Desulfurization Scrubber Produced Gypsum

More than half of the electricity generated in the U.S. is produced by coal-fired facilities that are large producers of the toxic gas sulfur dioxide. A popular technique to limiting sulfur dioxide emissions is to utilize wet flue gas desulfurization (FGD) technologies, which convert the gas to gypsum. As part of this process, mercury, which results from burning certain coals, is transferred from the flue gas and to the FGD system. However, high concentrations of mercury in the gypsum can affect the re-use potential of this coal-utility by-product, reducing the cost benefit of the FGD system and requiring more gypsum to be disposed in hazardous landfills. Phase I will determine the feasibility of using a proprietary organo-thiol polymer, FGS-PWN, to complex and separate mercury from the synthetic gypsum at the bench level. Separation by both floatation and settling will be demonstrated. Phase II will conduct pilot studies using the organo-thiol polymer to separate mercury from synthetic gypsum. Commercial Applications and other Benefits as described by the awardee: By using the FGS-PWN polymer, mercury concentration in the synthetic gypsum should be easily within the specifications required by end users and cleaner than currently possible. In addition, the low volume Hg/FGS-PWN complex can be disposed of safely in a non-hazardous landfill. Because the polymer performance will not be affected, the financial benefit from the sale of the synthetic gypsum will be preserved. End users will have access to an inexpensive raw product, with cost savings passed on to the American public.