垃圾焚烧中氯化物对重金属Pb迁移转化特性的影响

The effects of chlorides (including inorganic chloride NaCl and organic chloride PVC) on Pb emission during MSW incineration were investigated using a tubular furnace and a simulated MSW containing heavy metals. The concentrations of heavy metals were measured by ICPAES after digesting of samples including bottom ash, fly ash and flue gas according to related US EPA methods. Heavy metal species in bottom ash and fly ash were identified by X-ray diffraction technique. The spectra of elements distributed and micrographs of bottom ash and fly ash were detected by energy dispersive X-ray system and scanning electron microscope, respectively. The results indicate that the emission of Pb tends to be enhanced with the increasing of chloride content, so partitioned in fly ash. The effect mechanism of inorganic chloride NaCl and inorganic chloride PVC on Pb emission is different. NaCl tends to form PbCl2 with Pb. For PVC, besides the resultant PbCl2, PVC tends to form Pb(ClO4)2, PbCl2O4 and PbO2 with Pb. Incineration temperature and residence time are two major factors influencing the partitioning of Pb.