Trace and Minor Element Distribution in a Forced-Oxidation, Limestone- Slurry Flue-Gas-Desulfurization Unit

摘要

Trace elements such as selenium and mercury volatilized during coal combustion may accumulate in the solids and liquids in flue-gas-desulfurization (FGD) units along with sulfur and nitrogen oxides. The abundance and distribution of trace elements among the solid and aqueous phases in a wet-limestone FGD unit are likely to depend on the operating efficiency of the unit, redox conditions, and precipitation and dissolution reactions. The abundance of trace elements in the FGD unit relative to the other combustion wastes and the feed coal has implications for the use of gypsum produced in the FGD unit and for atmospheric emissions from the power plant. Changes in the chemical environment of the FGD gypsum during storage, processing, and disposal may release the trace elements. This paper describes preliminary results of chemical and mineralogical analyses of materials used and produced in a forced-oxidation, limestone-slurry FGD unit.