【作者】 文娟；

【导师】 刘清才；

【作者基本信息】 重庆大学 ， 环境科学， 2008， 硕士

【摘要】 垃圾焚烧处理能有效实现垃圾的减量及资源化利用,降低垃圾对环境的危害,是目前国内外垃圾处理的主要方法之一。垃圾焚烧所产生的飞灰中含有浸出浓度超出固体废物浸出毒性鉴别标准的重金属等物质,若不经有效处置,会带来严重的环境污染。本文针对垃圾焚烧飞灰重金属污染问题,以重庆市同兴垃圾焚烧厂飞灰为研究对象,对垃圾焚烧飞灰理化性质、高温熔融分离工艺、重金属在烟气中迁移规律等进行了实验研究。结果表明:垃圾焚烧飞灰密度为0.6723 g/cm3,粒径分布较均匀,颗粒表面粗糙;平均热灼减率达9.185%;飞灰中各元素主要以氧化物形式存在,主要氧化物有:CaO(23.79%)、SiO2(15.24%),其次为:Al2O3、Na2O、K2O、Fe2O3、MgO。飞灰浸出毒性试验表明,飞灰的中锌、铅、镉、铬等浸出浓度均高于固体废物浸出毒性鉴别标准。采用高温熔融分离,袋式除尘法收集处理熔融烟气的工艺方法,结合热力学模拟计算分析,研究了焚烧垃圾飞灰高温熔融分离过程中重金属在烟气中的迁移分布规律。熔融分离的适宜工艺条件为:温度1350℃、碱度1.1、熔融时间25min左右。高温熔融分离过程中,迁移到烟气中的主要元素为Zn、Pb、Cl、K、Na,其中ZnS、ZnO、PbCl2、KCl、NaCl等占90%左右。其他元素Mn、Cu、Cd、Ba、As、Hg、Ti、Cr在烟气中为微量。Hg主要以氯氧化物、硫氯化物形态存在,可通过冷凝收集全部分离。采用铁浴进行熔融分离时, Cr、Mn、Fe、Cu等高沸点元素主要分配在铁相中,其中Mn、Fe进入铁相达到90%以上, Cr、Cu约70%进入铁相中。Pb、Zn的挥发率较高,在本实验条件下,熔融20分钟后,进入烟气中的Pb、Zn分别为80%、70%左右,随熔融温度、碱度增加而上升,几乎不随熔融时间发生变化;Cr的挥发率非常低,随熔融时间增加而降低。更多还原

【Abstract】 The incineration technology has become the most popular treatment for municipal solid wastes (MSW), for it can minimize the weight and volume of solid wastes, utilize the energy released by combustion and reduce the harmfulness. However, the incineration residues and fly ash contain considerable amounts of various heavy metals , such as Cd、Pb、Cu、Zn、Cr and so on, which would bring serious environmental pollution if without effective treatment before emission. Thus the fly ash melting treatment is proposed to solve this problem.The properties of municipal solid wastes incineration fly ash (MSWI) produced by Tongxing MSW incineration plant in Chongqing was studied by experiment, and the results show that: the average density of MSWI fly ash is 0.6723g/cm3, and its particle size is well-distributed. The MSWI fly ash has a complex composition, with CaO、SiO2 as the major constituents , separately accounting for 23.79% and 15.24% , and Al2O3、Na2O、K2O、Fe2O3、MgO as the secondary constituents. Through the heavy-metal leaching characteristic experiment, it is found that the concentration of Zn、Pb、Cd and Cr in MSWI fly ash exceed Solid Waste Leaching Character Standard. Effective treatment should be taken for MSWI fly ash.Combined with thermodynamic analysis, melting experiment was taken to study the migration of heavy metals in MSWI fly ash melting process, and fabric filter bag was applied to collect melting fly ash(MFA). The optimal melting condition was abtained: temperature for 1350℃, bisicity of 1.5, and melting period 25min. The main elements of MFA are Zn、Pb、S、Cl、K. And KCl、NaCl、ZnS、ZnO、PbCl2 constitude MFA for about 90%. Mn、Cu、Cd、Ba、As、Hg、Ti、Cr are trace elements. Hg exists with its oxychloride and sulfo-chlorinated state, and can be all collectd by condensing.The iron bath melting system can create a reducible atmosphere, which could accelerate Cr、Mn、Fe、Cu distribute out from residues into iron phase. The proportion of Mn、Fe distributing in iron phase is beyond 90%, and about 70% of Cr、Cu distribute in iron phase.The evaporation rate of Pb, Zn is separately high to about 80% and 70%, under experimental condition after 25min, and is affected by basicity and melting temperature obviously, increasing both with the increasing bisicity and the increasing melting temperature, but merely changing with melting period. The evaporation rate of Cr is very low, decreasing with the rising period.更多还原