垃圾焚烧中硫化合物对Cd、Pb迁移和转化的影响

Effects of sulfur compounds on Cd and Pb partitioning and speciation in a simulated MSW incinerator

采用管式炉和模拟垃圾对垃圾中不同硫化合物对重金属Cd、Pb迁移分布特性的影响进行了研究,使用ICP-AES(美国EPA消解方法)、SEM/EDS和XRD分析技术对重金属浓度、灰渣表面形貌及成分和灰渣X射线衍射成分等进行了分析。结果表明:硫化合物对Cd、Pb迁移分布特性有着显著影响,它易与Cd形成金属硫化物和硫酸盐,从而使Cd更多地向底渣分布;同时使Pb更易向飞灰分布。另外,随着S和Na2S加入量的增加,Pb在底渣中的分布越来越少;但是随Na2SO4加入量的增加,Pb却会增加。

The effects of sulfur compounds （including sulfur, sulfide, sulfite and sulfate） on Cd and Pb emissions from municipal solid waste （MSW） incineration were investigated using a simulated tubular furnace and simulated MSW with heavy metals. The heavy metals concentrations were measured using ICP-AES after digesting of the samples including bottom ash, fly ash, and flue gas according to USEPA methods. Heavy metal species in the bottom ash and fly ash were identified by X-ray diffraction. Micrographs of the bottom ash and fly ash were obtained using a scanning electron microscope. The results indicate that the Cd and Pb partitioning were significantly affected by the sulfur compounds. Sulfur compounds tend to enhance the potential to form cadmium sulfide and cadmium sulfate and shift more Cd towards the bottom ash. However, Pb partitioning in the bottom ash decreased as the amount of S and Na2S increased and increased as the amount of Na2SO4 increased.