Volatilization Behavior of Heavy Metal Chlorides from

Molten fly ashes generated from melting treatment of municipal solid waste and automobile shredder residues are characterized as hazardous waste due to the high content of heavy metals such as Zn, Pb and Cu. In addition, the heavy metal resources could be depleted in the near future and thus, the research towards conservation of metal resources is required. In the present work, volatilization behavior of heavy metal chlorides from molten fly ashes under reduced pressure was investigated. As samples, ZnCl2, PbCl2 and CuCl reagents, model fly ashes composed of ZnCl2, PbCl2 and CuCl reagents at various ratios with/without additional components, and real molten fly ash were used. As a result, it was found that respective volatilization rates of ZnCl2, PbCl2 and CuCl in single component systems were higher than volatilization rates of ZnCl2, PbCl2 and CuCl in three-component system. Further, the effect of fly ash composition of Al2O3, NaCl, KCl and CaCl2 on metal volatilization was investigated. As a result, the presence of inorganic chlorides of NaCl, KCl and CaCl2 were found to reduce the amount of volatilized heavy metals from model fly ashes, and thus the amount of volatilized heavy metal chlorides from real molten fly ash was found to be 0.27 – 0.65 times lower than that of model fly ash without addition of NaCl, KCl and CaCl2.