DISTRIBUTION OF SELENIUM, ARSENIC, AND MERCURY IN ESP FLY ASHES

The distribution and natural capture of hazardous elements by coal-combustion fly ash has been of interest in recent years. In particular, the capture of Hg by fly ash carbons is of concern because of its potential to offset more-expensive engineered solutions. Less is know about the distribution of Se in pollution-control systems. Two previous studies of Se distribution, one at a Kentucky plant burning eastern Kentucky high volatile A bituminous coal and another at a Tennessee plant burning a western US bituminous: Powder River Basin subbituminous blend (with added tire-derived fuel), showed extreme concentrations in the first ESP row. Additional collections for this study do not show the same patterns, indicating that Se distribution can be inconsistent and also does not appear to precisely follow the pattern of an increase with a decrease in flue gas temperature, as observed with other volatile trace elements in coal combustion systems.