西北典型垃圾焚烧飞灰基础物性及浸出毒性研究

Research on physico-chemical characteristics and its leaching toxicityof fly ash from a MSW incinerator in Northwest China

垃圾焚烧飞灰的物相与矿相组成是其内部矿物学信息的直观表现,为了明晰垃圾焚烧飞灰的基础物化性质,利用X射线荧光光谱分析仪、X射线衍射、BET比表面积分析仪、扫描电子显微镜、电子探针等检测手段,对中国西北地区产出的2种典型垃圾焚烧飞灰进行物相组成、矿相结构、孔道及比表面积、元素赋存形态研究,并通过固体废物毒性浸出试验(TCLP),对2种典型垃圾焚烧飞灰的浸出毒性进行分析比较。结果表明:污泥垃圾与生活垃圾经过焚烧后产出的飞灰主要化学组成是CaO、SiO 2和Al2O3,同时伴生有Pb、Cr等重金属毒害元素,污泥焚烧飞灰主要以磷酸铝、石英、铝硅酸钙等矿相为主,并夹杂氧化铁矿相,其毒性金属种类较少且弥散分布在飞灰内部,仅有少部分Ti与铝硅酸盐结合。生活垃圾焚烧飞灰主要以铝硅酸钙相的形式存在,并夹杂有部分可溶性的氯盐,飞灰内部S/Ca、Ca/Si/Al相对富集,其他元素与Cl结合,毒害金属种类繁多且弥散分布。通过TCLP浸出试验发现,这2种垃圾焚烧飞灰均存在重金属被浸出的可能性,存在一定的环境风险,因此需要对垃圾焚烧飞灰进行妥善处置,降低其环境风险影响。

The chemical composition and mineral phase of waste incineration fly ash are the intuitive expression of its internal mineralogical information.In order to clarify the basic physical and chemical properties of waste incineration fly ash,X-ray fluorescence spectrometer,X-ray diffraction,BET specific surface area analyzer,scanning electron microscope,electron probe and other detection methods were used to study the chemical composition,mineral phase structure,pore and specific surface area,and element occurrence morphology of two typical waste incineration fly ash produced in Northwest China.The leaching toxicity of two typical waste incineration fly ash was analyzed by the toxicity characteristic leaching procedure(TCLP).The results show that the main chemical composition of fly ash produced after incineration of sludge garbage and domestic garbage are CaO,SiO 2 and Al2O3,accompanied by heavy metal toxic elements such as Pb,Cr.The mineral phase of sludge incineration fly ash is mainly aluminum phosphate,quartz,calcium aluminosilicate,mixed with iron oxide ore phase,and its toxic metal species are less and dispersed in the fly ash,only a small part of Ti is combined with aluminum Silicates.The mineral phase of the fly ash from domestic waste incineration mainly exists in the form of calcium aluminosilicate phase and is mixed with some soluble chloride salts.S/Ca and Ca/Si/Al are relatively enriched in the fly ash from domestic waste incineration,other elements are combined with Cl,and toxic metals are various and dispersed.Through TCLP leaching experiments,it is found that there is the possibility of heavy metals leached in incineration fly ash.Therefore,it is necessary to properly dispose of waste incineration fly ash to reduce its environmental risks.