Speciation analysis of Hg, As, Pb, Cd, and Cr in fly ash at different ESP’s hoppers

Abstract

In the power plants, the particle size of fly ash was gradually decreased from the front row to the last row of the hopper. The high mercury captured rate was shown with the high unburned carbon content in the front row of the hopper. 80% of mercury captured in the front hopper was in the residual fraction and the rest was in the oxidizable fraction. The other four trace elements tended to be captured more with the smaller particle size of fly ash in the latter hoppers. Above 90% of lead in fly ash at different hoppers was in the speciation of the residual fraction. This indicated that the lead was the less tendency to be leached out during landfill. The speciation of acid-soluble, reducible, and oxidizable fraction for As, Cr and Cd was significantly increased in the fly ash at different hoppers. This indicated that the combustion technology in each power plant had a significantly impact on the speciation of these trace elements in different hoppers. Thus, the usage of the separation technology method to better understand the behavior of trace elements in the fly ash to avoid fly ash’s disposal through increasing the beneficial use of fly ash.