炉内添加剂对垃圾焚烧过程中重金属捕集影响的试验研究

Experimental Study on the Capture of Heavy Metals by In-furnace Additives During MSW Incineration

在管式炉内对垃圾焚烧过程中不同炉内添加剂下重金属Zn、Cu、Pb、Cd、Cr的捕集效果进行了研究,用原子吸收分光光度计和扫描电镜–能谱仪对焚烧底渣中重金属分布、底渣表面形貌和表面元素分布进行了分析。结果表明,1 000℃下垃圾焚烧底渣结构形貌非常复杂,主要有针状、层状、颗粒状结构,极少部分呈轻微融化状态;底渣消解宜使用HCl/HNO3/HF/HClO4而不应使用王水;在无添加剂情况下垃圾中重金属挥发性顺序为:Pb>Cd>Cu>Cr>Zn;Si的存在可显著减少Zn的挥发;沸石和石灰石对Zn、Cr有一定的捕集效果,砖粉和玻璃粉对Zn、Cu有很好的捕集效果,而高岭土无捕集效果;垃圾组分中硅铝原子比3:1最有利于降低焚烧中重金属挥发。

The capture effects of different in-furnace additives on Zn,Cu,Pb,Cd and Cr were studied during municipal solid waste(MSW) incineration.Atomic absorption spectrometer(AAS) and scanning electron microscope-energy dispersive spectroscopy(SEM-EDS) were used to detect the distribution of heavy metals in bottom ash and ash surface and to observe the surface morphology.The results show that: the bottom ash presents various surface morphologies which consist mainly of acicular,flake and particle structure and very few of melt.Mixed acids of HCl/HNO3/HF/ HClO4 instead of aqua regia can be used for the digestion of bottom ash.The volatility of 5 heavy metals follows the sequence of Pb>Cd> Cu>Cr>Zn in the additives-free case and the existence of Si can reduce the volatile of Zn significantly.Zeolite and limestone show a certain capture efficiency of Zn and Cr while brick and glass powder show a good capture efficiency of Zn and Cu,but kaolinite shows no capture effect.Si-Al atomic ratio of 3:1 in waste components is the best ratio to reduce heavy metals volatility.