Leaching Characteristics of Semidry Flue Gas Desulfurization Products

Leaching of six elements-namely, Cu, Zn, Pb, Cd, Ni, and F from two semidry flue gas desulfurization ash samples and one waste gypsum sample collected from two different iron and steel plants and one power plant in Hebei, has been reported. Various extracting agents were used to conduct leaching experiments for desulfurization ashes. The dissolution of trace elements contained in the ashes were determined in order to estimate the possible impacts of the materials for stacking, back-filling or road-paving on the under-ground water and the environment and to assess the possibility of contamination of the sites by release of these ions. The alkalinity greatly determines the ion concentration in leaching liquids. It appears that the risk pollution of ground water as well as of surface water may not be avoidable if the ash alone is used for stacking et al. Nevertheless heavy metal contents of three samples in the leaching solution are far below the specified value regulated in "Identification standards for hazardous waste - Identification for extraction toxicity"(GB5085.3-2007, in China).