利用热等离子体熔融垃圾焚烧飞灰

为了评价垃圾焚烧飞灰的热等离子体熔融处理效果, 研究SiO2和CaO对重金属固化效果和重金属毒性浸出特性的影响. 在飞灰中添加一定比例的SiO2和CaO, 配置成不同的配灰样品, 利用纯氩热等离子体在1 400～1 500 ℃下, 对飞灰及配灰进行熔融玻璃化的实验研究, 分别利用X射线能量色散谱仪(EDX)、场发射扫描电子显微镜(FSEM)、X射线衍射仪(XRD)和毒性浸出方法(TCLP)分析飞灰和熔渣的化学组成、微观结构、晶相组成和重金属毒性浸出特性. 结果表明, 热等离子体熔融所得熔渣为无定形的玻璃体, 重金属浸出质量浓度均远低于毒性标准. SiO2和CaO的添加都可以改善重金属固化效果, CaO比SiO2对Cu、Zn、Cd和Pb挥发的抑制效果更好. SiO2的添加可以改善熔渣中重金属的浸出特性, 而CaO的作用与之相反.     

城市生活垃圾焚烧飞灰中重金属的固化/稳定化处理

城市生活垃圾焚烧飞灰已被明确规定为危险废物,其中含有的大量有毒重金属对自然环境和人类生存会造成严重危害.综述了目前常用的水泥固化、烧结固化、熔融固化、药剂稳定化四种固化/稳定化垃圾焚烧飞灰中有毒重金属的方法,对比分析了各项技术的优缺点;对城市生活垃圾焚烧飞灰中重金属固化/稳定化处理的发展前景进行了展望,指出资源化利用是未来发展的必然趋势.     

飞灰熔融分离过程中重金属Cu的迁移分布规律

为研究危险固体废弃物飞灰中的重金属Cu在垃圾焚烧飞灰熔融分离过程中的迁移分布规律,采用重庆同兴垃圾焚烧发电厂产生的焚烧飞灰进行熔融分离实验, 以重金属Cu为研究对象,探讨熔融温度、熔融时间、碱度、熔池配比等因素对熔融过程中Cu的迁移分布规律的影响。结果表明, 熔融温度对Cu在熔融分离过程中的迁移分布影响最大,随着熔融温度的升高,重金属Cu在铁相中的分布呈现上升趋势,熔融时间、碱度和熔池配比的影响相对小一些。       

焚烧飞灰熔融特性与熔渣利用技术研究进展

垃圾焚烧飞灰中含有高浸出浓度的Pb,Cd,Cu,Zn等重金属,属于危险废物。高温熔融技术可以有效地控制焚烧飞灰中的重金属污染物。从飞灰无害化和资源化2个角度介绍了熔融技术的研究进展,分析了熔融技术的优缺点,在综述国内外研究成果的基础上,为今后焚烧飞灰的热处理技术提出了研究方向。     

利用垃圾焚烧飞灰固化污染底泥的实验研究

为探讨利用垃圾焚烧飞灰代替水泥进行污染底泥固化的可行性,研究了不同配比的底泥、水泥、垃圾焚烧飞灰的固化体抗压强度及浸出毒性.结果表明：固化剂中用20%的垃圾焚烧飞灰替代10%的水泥配置的固化体7.d,其抗压强度可达0.24.MPa,重金属浸出浓度低于毒性标准,固化体可进入固废填埋场填埋处置.     

城市垃圾焚烧飞灰熔融动力学研究

在高温差示扫描量热差热分析（DSC-DTA）实验基础上，对垃圾焚烧飞类熔融过程进行研究，建立飞灰熔融动力学模型，在惰性气氛（N2）和氧化气氛（O2）下，20-1450℃的温度对两种垃圾焚烧飞灰的熔融过程进行研究，实验采用了三种温升速率（5、10、20℃/min），并研究了CaO添加剂对飞灰熔融的影响。飞灰熔融过程包含干燥脱水、多晶转变和熔融相变三种反应，脱水发生在100-200℃，多晶转变发生在480-670℃，熔融发生在1136-1231℃，在1174℃达到峰值，提出了垃圾焚烧飞灰熔融的0级反应动力学，并得到飞灰熔融反应表现活化能。     

地聚物对固化焚烧飞灰的研究

垃圾焚烧处理技术产生的飞灰浓缩了重金属等一些高毒性当量的危险成分, 如果处理不当会 产生二次污染, 因此焚烧飞灰被认为是危险废物, 必须进行特殊处理.论文对地聚物固化垃圾焚烧 飞灰的工艺及养护条件进行了实验研究, 以抗压强度和重金属浸出质量浓度为效果表征量, 研究了 地聚物固化飞灰的合成配方.结果表明:氧化物配比为m(Na2O)∶m(SiO2)=0 .30 , m(SiO2)∶m (Al2O3)=4 .7 时, 飞灰掺量为40 %的固化体在养护7 天后抗压强度能达到31 .25 MPa , 固化体中 Pb , Zn ,Cu 和Cr 的浸出质量浓度分别达到0 .183 8 , 0 .023 1 , 0 .008 1 , 0 .367 9 mg/L .     

生活垃圾焚烧飞灰重金属特性分析

对国内四个不同的垃圾焚烧厂产生的飞灰进行物理及化学特性分析.四种飞灰在颗粒尺寸分布上有相似的规律,飞灰中重金属的质量分数分析结果表明采用纯垃圾焚烧的炉排炉飞灰中的质量分数高于掺煤混烧的流化床焚烧飞灰中的质量分数.随着飞灰颗粒尺寸的减小,飞灰中重金属的浓度呈现增加的趋势.飞灰的渗滤特性表明,飞灰中Ca质量分数越高,飞灰的酸中合能力越强,且重金属的渗出率受飞灰渗滤液的pH影响大,而在碱性渗滤条件下受飞灰中重金属质量分数的影响小.     

地聚物固化体抗高温性能及数学模型研究

地聚物对焚烧飞灰中的重金属具有良好的固定作用.为了进一步探索固化飞灰后的地聚物固 化体的抗环境侵蚀性能, 开展了固化体高温—恒温时间—地聚物抗压强度的研究及经受高温后固 化体的重金属浸出试验, 探讨抗压强度与高温、恒温时间之间的关系以及地聚物固化垃圾焚烧飞灰 的稳定性.通过对固化体试块的高温试验以及对不同温度、不同恒温时间下固化体抗压强度试验, 分析这三者之间的关系, 建立数学模型, 并根据实验结果拟合温度—恒温时间—抗压强度的三维 曲面.     

脲酶菌的筛选及其对垃圾焚烧飞灰的固化

焚烧是当前城市垃圾处置的重要方式,焚烧飞灰及其重金属却是威胁周围环境的一种污染源。为降低这种污染,从植物根际筛选获得高活性脲酶菌,并比较脲酶菌固化焚烧飞灰后的抗压强度、颗粒级配及重金属稳定化效果。结果表明:从丹参根际土壤内分离获得2株高效脲酶菌Bacillus aryabhattai UR-F51和Pseudomonas taiwanensis UR-121;将脲酶菌与飞灰按一定比例混合后固化,菌株UR-F51和UR-121使固化飞灰的抗压强度分别增加48.00%和27.00%,固化颗粒粒径增加10.00%～145.00%;飞灰中重金属(Cr、Ni、Cu、Cd、Hg和Pb)的固化率分别为15.27%～37.23%、41.49%～90.43%、37.17%～99.73%、42.86%～71.42%、20.00%～40.00%和47.06%～82.35%。脲酶菌可显著提升飞灰及其重金属的固化效果,菌株UR-F51的固化效果最好,为缓解城市生活垃圾焚烧飞灰污染提供一种新途径。     

Characteristics of MSWI fly ash during vitrification

The vitrification characteristics of municipal solid waste incinerator (MSWI) fly ash were investigated. Effects of temperature on the binding efficiency of heavy metals, the change of chemical compositions and the weight loss of fly ash in the range of 800-1350 ℃ were studied. Toxicity Characteristic Leaching Procedure (TCLP) of the United States was used to analyze the leaching characteristics of heavy metals in fly ash and molten slag. Results indicate that chemical compositions, the weight loss of fly ash and the binding efficiency of heavy metals in fly ash have a tremendous change in the range of 1150-1260 ℃. The percentage of CaO, SiO2 and Al2O3 increases with the increasing temperature, whereas it is contrary for SO3, K2O, Na2O and Cl; especially when the temperature is 1260 ℃, the percentage of these four elements decreases sharply from 43.72% to 0.71%. The weight loss occurs obviously in the range of 1150-1260 ℃. Heavy metals of Pb and Cd are almost vaporized above 1000 ℃. Cr is not volatile and its binding efficiency can reach 100% below 1000 ℃. Results of TCLP indicate that the heavy metal content of molten slag is beyond stipulated limit values.     

Microstructures and thermal properties of municipal solid waste incineration fly ash

To analyze the feasibility of utilization of thermal technology in fly ash treatment, thermal properties and microstructures of municipal solid waste incineration (MSWI) fly ash were studied by measuring the chemical element composition, specific surface area, pore sizes, functional groups, TEM image, mineralogy and DSC-TG curves of raw and sintered fly ash specimens. The results show that MSWI fly ash particles mostly have irregular shapes and non-typical pore structure, and the supersonic treatment improves the pore structure; MSWI fly ash consists of such crystals as SiO₂, CaSO₄ and silica-aluminates, and some soluble salts like KCl and NaCl. During the sintering process, mineralogy changes largely and novel solid solutions are produced gradually with the rise of temperature. Therefore, the utilization of a proper thermal technology not only destructs those persistent organic toxicants but also stabilizes hazardous heavy metals in MSWI fly ash.     

MSWI fly ash based novel solidification/stabilization matrices for heavy metals

The possibilities of MSWI fly ash as a major constituent of novel solidification/stabilization matrices for secure landfill were investigated by mixing MSWI fly ash with rich aluminum components, which was added as bauxite cement or metakaolinite instead, to form Friedel and Ettringite phases with high fixing capacities for heavy metals. The physical properties, heavy metals-fixing capacity, mineral phases and its vibration bands in the novel matrices were characterized by compressive strength, TCLP（toxic characteristic leaching procedure）, XRD （x-ray diffraction） , DTG （derivative thermogravimetry）, and FTIR （fourier transform infrared spectroscopy）, respectively. The Tessier＇s five-step sequential extraction procedure was used to analyze the fractions of chemical speciation for Pb, Cd and Zn ions. The experimental results indicate that Friedel-Ettringite based novel solidification/stabilization matrices can incorporate Pb, Cd and Zn ions effectively by physical encapsulation and chemical fixation, and it exhibits a great potential in co-landfill treatment of MSWI fly ash with some heavy metals-bearing hazardous wastes.     

垃圾焚烧飞灰处理高浓度含磷废水的动力学

采用能谱分析（EDS）,荧光光谱分析（XRF）,透射电子显微镜（TEM）测试的手段结合水化学理论研究了垃圾焚烧（MSWI）飞灰去除废水中高浓度磷酸盐的动力学。结果表明：MSWI飞灰除磷速率较快,303K下30min磷去除率95％;除磷过程宏观表现为吸热过程,但对外加能量要求较低;除磷反应对MSWI飞灰中的重金属有很好的稳定化效果,反应后溶液中重金属未检出。化学沉淀是MSWI飞灰除磷的主要机制,Ca、Fe、Zn等均可为反应提供阳离子。反应物PO。”与可溶性产物的内扩散过程是飞灰除磷的控制步骤,宏观动力学过程适用于球体内扩散控制模型,磷酸盐反应率与时间的关系可描述为1—3（1-x）^2/3＋2X—kt,实验得到表观活化能约10．06kJ／mol。     

The Cement Solidification of Municipal Solid Waste Incineration Fly Ash

The chemical composition, the content and the leachability of heavy metals in municipal solid waste incineration （ MSWI） fly ash were tested and analyzed. It is shown that the leachability of Pb and Cr exceeds the leaching toxicity standard, and so the MSWI fly ash is considered as hazardous waste and must be solidifled. The effect of solidifying the MSWI fly ash by cement was studied, and it is indicated that the heavy metals can be well immobilized if the mass fraction of the fly ash is appropriate. The heavy metals were immobilized within cement hydration products through either physical fixation, substhtaion, deposition or adsorption mechanisms.     

Effect of MSWI fly ash and incineration residues on cement performances

The activities of municipal solid waste incineration (MSWI) fly ash and incineration residues were studied contrastively, through the component analysis and the activity ratio tests. The mechanical properties, hydration mechanism and leaching toxicity of the hardened cement paste mixing with MSWI fly ash and incineration residues were investigated. The experimental results indicated that the active constituents (CaO+Al₂O₃+Fe₂O₃) in MSWI fly ash were higher than those in incineration residues. Therefore the activity ratio of MSWI fly ash was 43.58%, twice as much as that of incineration residues. Meanwhile, the hydration of cement was delayed by mixing with MSWI fly ash and incineration residues, which also reduced the cement strength markedly. By adding with exceeding 20% MSWI fly ash, the specimens expanded and microcracks appeared. The leaching toxicities of cement pasted mixed with MSWI fly ash and incineration residues were lower than the Chinese national standard. Accordingly the cement mixed by MSWI fly ash and incineration residues can be considered as the environment-friendly materials.     

Synthesis and heavy metal immobilization behaviors of fly ash based gepolymer

Two aspects of studies were carried out: 1) synthesis of geopolymer by using fly ash and metakaolin; 2) Immobilization behaviors of fly ash based geopolymer in a presence of Pb and Cu ions. As for the synthesis of fly ash based geopolymer, 4 different fly ash content (10%, 30%, 50%, 70%) and 3 types of curing regimes (standard curing, steam curing and autoclave curing) were investigated to obtain the optimum synthesis condition based on the compressive and flexural strength. The experimental results show that geopolymer, containing 30% fly ash and synthesized at steam curing (80° for 8 h), exhibits higher mechanical strengths. The compressive and flexural strengths of fly ash based geopolymer reach 32.2 MPa and 7.15 MPa, respectively. Additionally, Infrared (IR) and X-ray diffraction (XRD) techniques were used to characterize the microstructure of the fly ash geopolymer. IR spectra shows that the absorptive band at 1086 cm⁻¹ shifts to lower wave number around 1033 cm⁻¹, and the 6-coordinated Al transforms into 4-coordination during the synthesis of fly ash based geopolymer. The resulting geopolymeric products were X-ray amorphous materials. As for immobilization of heavy metals, the leaching tests were employed to investigate the immobilization behaviors of the fly ash based geopolymer synthesized under the above optimum condition. The leaching tests showed that fly ash based geopolymer can effectively immobilize Cu and Pb heavy metal ions, and the immobilization efficiency reached 90% greater when heavy metals were incorporated in the fly ash geopolymer in the range of 0.1% to 0.3%. The Pb exhibits better immobilization efficiency than the Cu, especially in the case of large dosages of heavy metals.