Potential for mercury vapor release from coal combustion by-products

Abstract

Determination of the mechanisms of mercury release from coal combustion by-products (CCBs) is one area of research at the Energy and Environmental Research Center (EERC). One task of this research is to determine the level of mercury that would offgas from various CCBs. In these experiments, six CCB samples were tested for mercury vapor release at ambient and near-ambient temperatures. The results have shown no clear evidence that the rate of mercury release is related to the bulk mercury concentration. The six samples are being retested for ambient temperature release. These new experiments are being done in duplicate in an improved version of the apparatus to verify previous results. Because of improved methods, results indicate that the vapor release of mercury is an order of magnitude lower than previously thought. It is estimated that an annual coal-fired power plant production of 200,000 tons of fly ash a year would potentially offgas less than 0.3 g of mercury.