气氛对焚烧飞灰熔融过程中重金属行为的影响  

Influence of Atmospheres on Behavior of Heavy Metals During Melting Process of Fly Ashes from Municipal Solid Waste Incinerator

作　　者：王学涛[1] 金保升[1] 仲兆平[1] 党小剑[1] 

机构地区：[1]东南大学洁净煤发电及燃烧技术教育部重点实验室,江苏省南京市210096

出　　处：《中国电机工程学报》2006年第7期47-52,共6页Proceedings of the CSEE

基　　金：教育部高等学校博士点基金项目(20030286005);江苏省建设系统科技计划项目(JS200311)。

摘　　要：在小型熔融炉上将焚烧飞灰进行熔融处理实验，系统地研究了不同气氛对几种重金属固溶、挥发行为的影响，并用扫描电镜对试样微观结构进行了分析。结果表明，在氧化性气氛下重金属Cr、Ni、Cu、As的固溶率与其熔沸点呈正相关，固溶率依次为：Cr〉Ni〉Cu〉As；低沸点重金属Pb、Cd、Hg等在熔融过程中均有很高的挥发性，由于熔融时Zn易形成Zn2SiO4、ZnSiO3和ZnAl2O4等不易挥发的化合物，故其挥发率较低。还原性气氛有利于Ni、Cr、Cu和As的固溶，有助于Hg、Cd、Zn的挥发，但对Pb的挥发却有抑制作用，Pb的挥发率在1100-1400℃范围均小于50％。还原性气氛下飞灰的熔融效果明显优于氧化性气氛，低沸点重金属的挥发率也高于氧化条件，熔渣断面气孔基本消失，且表面平整光滑，结构致密紧凑。Fly ashes from municipal solid waste incinerator are melted using a small-scale furnace. Effects of the behavior of several heavy metals fixation and volatilization have been systematically studied. The microstructures of samples are analyzed by scanning electron microscope. Experimental results show that the fixation proportions of chromium, nickel, copper and arsenic would increase with the elevation of their melting and boiling points under oxidizing atmosphere, The proportions of fixation is in sequence of chromium〉nickel〉copper〉arsenic. Heavy metals having low melting and boiling, such as lead, cadmium and mercury, are easily volatized during melting process. The volatilization rate of zinc is very low due to easily forming the nonvolatile compounds, like Zn2SiO4, ZnSiO3, and ZnAl2O4. The reducing atmosphere would be propitious to enhancing the fixation rates of chromium, nickel, copper and arsenic. It is confirmed that mercury, cadmium, and zinc are more easily vaporized under reducing atmosphere. While the volatilization rate of lead would be inhibited at the same condition. The volatilization rate of lead is less than 50 % at 1100 to 1400 ℃. Samples under reducing condition are superior in melted effects to that oxidizing condition. The volatilization of low-boiling heavy metals under the reducing atmosphere is larger that the oxidizing atmosphere. Samples molten become full smooth and much compact in structure, while the molten samples have no apertures on the apparent section.

关 键 词：热能动力工程 焚烧飞灰 熔融 重金属 氧化性气氛 还原性气氛 

分 类 号：TK229[动力工程及工程热物理—动力机械及工程] X701[环境科学与工程—环境工程]