焚烧飞灰热处理过程中重金属挥发特性研究

The evaporation behaviour of selected heavy metals during the heat treatment of ash from incinerated urban solid wastes

采用可控硅温控模式（708P）的高温熔融管式电炉，在650～1350℃研究了热处理温度、时间以及载气种类（空气／氮气）对垃圾焚烧飞灰中重金属Pb，Cu，Cd和Zn挥发特性的影响，同时收集二次飞灰（凝结的挥发物及烟尘）并对其成分和物相进行了分析．结果发现：温度和时间对重金属挥发影响最为明显；在650～1350℃，重金属Pb，Cd，Cu和Zn的挥发率均随着温度升高而增大，其挥发率从大到小依次为Pb，Cd，Cu，Zn，挥发率最大值出现在1150～1320℃的范围内；X射线衍射仪和X荧光光谱仪分析表明，二次飞灰成分以NaCl和KCl为主，重金属Pb以双金属氯化物KPb2Cl5形式挥发．

The experiment used a alumina tube furnace with a programmed temperature controller （Model 708 P） to investigate the evaporation of selected heavy metals （Pb,Cd,Cu,Zn） in the ash from incinerated urban solid waste during the heat treatment process at 650～1350 ℃. The parameters included heating temperature, heating time, and the type of carrier gas（air and nitrogen）. The results indicated that heating temperature and time were more obvious than the type of carrier gases on evaporation. The evaporation of heavy metals had a different degree accretion along with increasing temperature in air and nitrogen at 650 ～1 350℃, and the order was Pb, Cd, Cu, Zn. The experiments had revealed that the maximum evaporation,of the heavy metals Pb, Cd, Cu and Zn took place at 1 150～ 1 320℃. Analysis of X-fay＇fluorescence spectroscopy and X-ray diffraction demonstrated that the volatiles were mainly composed of chloride of Na and K, Pb vaporized with the form of KPb2Cl5.