焚烧飞灰水泥固化技术研究

对利用水泥固化技术处理城市垃圾焚烧飞灰的效果进行了实验研究,分析了焚烧飞灰的主要化学组成,考察了水洗预处理对飞灰组成及固化效果的影响,研究了不同水泥/飞灰配比下所制得固化块的机械性能和重金属浸出毒性结果表明,焚烧飞灰主要元素包括Cl、Ca、O、K、S、Na等,此外还含有一定量的重金属包括Zn、Pb、Cu、Cd和Cr等.经过水洗预处理,焚烧飞灰中的可溶性盐类大大减少,飞灰固化块的强度得到了一定的提高,重金属浸出毒性则有明显的降低,预处理飞灰所制固化试块在养护28d后其重金属浸出毒性都能达到相应的控制标准,其中重金属Pb浸出浓度比原灰所制固化块降低了11%(飞灰添加量20%)～59%(飞灰添加量80%);随着水泥添加量的增加,飞灰固化块的抗压强度也随之提高.添加60%水泥的固化块在养护28d时的抗压强度最高,达425 N·cm-2;预处理飞灰固化块有着较强的抵御环境变化能力,重金属浸出毒性在pH值1～13的范围内都比较稳定.     

城市垃圾焚烧飞灰特性及水泥固化试验研究

试验分析了重庆市某城市垃圾焚烧发电厂飞灰的化学成分,研究了原飞灰的浸出毒性,考察了水泥对原飞灰和酸洗预处理飞灰中重金属的固化效果. 结果表明:飞灰中重金属Pb和Zn的浸出质量浓度均超过《危险废物浸出毒性鉴别标准》(GB5085.3-2007),因而被认为是危险废物,必须对之进行稳定化处理;酸洗预处理飞灰固化试块的抗压强度得到了一定程度的提高,其重金属Pb和Zn的浸出毒性均较相同配比、相同养护时间的原飞灰固化试块有明显降低;酸洗预处理飞灰固化试块抗压强度随掺入飞灰比例的降低和养护时间的延长而加大,在养护28 d时其抗压强度最高,达4.25 MPa;酸洗预处理飞灰固化试块在养护28 d时,其重金属Pb和Zn的浸出质量浓度分别比原飞灰所制固化试块降低了10.6%～59.0%和7.4%～73.7%.      

粉煤灰免烧砖的制备及性能研究

开发研制粉煤灰免烧砖可以充分利用工业废料、降低产品成本、保护资源和环境,同时还解决了电厂废渣的排放和堆存问题.本文分别以水泥和水玻璃作为粘结剂,添加免烧砖添加剂,进行了大量的试验研究.结果表明使用添加剂制备出的免烧砖在性能上已经达到了现有红砖的性能,应用前景良好,可以取得很好的社会效益和经济效益.     

城市垃圾焚烧飞灰特性及水泥固化实验研究

试验分析了重庆市某城市垃圾焚烧发电厂飞灰的化学成分,研究了原飞灰的浸出毒性,考察了水泥对原飞灰和酸洗预处理飞灰中的重金属的固化效果. 结果表明,飞灰中重金属Pb和Zn的浸出质量浓度均超过《危险废物浸出毒性鉴别标准》（GB5085.3-2007）,因而被认为是危险废物,必须对之进行稳定化处理;酸洗预处理飞灰固化试块的抗压强度得到了一定的提高,其重金属Pb和Zn的浸出毒性均较相同配比、相同养护时间的原飞灰固化试块有明显降低;酸洗预处理飞灰固化试块抗压强度随掺入飞灰比例的降低和养护时间的延长而加大,在养护28 d时其抗压强度最高,达4.25 MPa;酸洗预处理飞灰固化试块在养护28 d时,其重金属Pb和Zn的浸出质量浓度分别比原飞灰所制固化试块降低了10.6%-59.0%和7.4%-73.7%.     

铸造旧砂制备免烧砖及经济性分析

利用东风汽车公司十堰铸造基地排放的铸造旧砂制备了免烧免蒸砖,水泥加入量控制在3%以下,自然养护2 8d的抗压强度达到15MPa以上,符合蒸压灰砂国家标准(GB1194 5 - 1999)规定的优等品MU15级的要求。通过成本核算,铸造旧砂免烧砖标砖的生产成本能够控制在0 .10元块以下,具有较好的经济性。     

垃圾焚烧炉渣特性分析及制备免烧砖技术研究

炉渣制备免烧砖的技术作为固废建材化利用的手段之一,具有广阔的应用前景.基于炉渣基本性质,本文探讨了炉渣预处理、原料配比及养护方式等工艺条件对炉渣免烧砖的抗压强度和环保性能的影响,并提出了优化的工艺条件和参数.结果表明:炉渣的热灼减率为1.2%,物相组成与天然骨料相似,但水溶性氯离子含量为GB 50010-2010《混凝土结构设计规范》标准限值的8倍,且存在重金属超标风险,需要在固液比1:3的条件下水洗3次,使得水溶性氯离子含量削减87.5%;免烧砖原料配比较养护方式对抗压强度的影响更大,不添加炉渣的普通免烧砖的最终强度为全炉渣免烧砖的2.23倍;养护方式的影响体现在高温养护初期抗压强度增长速度较自然养护更快,但最终差异在±3%以内;选取全炉渣的免烧砖进行高温养护或者炉渣河砂配比1:1的免烧砖进行自然养护可使产品最终强度达到10 MPa或20 MPa的要求,且水溶性氯离子含量最终削减90%,重金属浸出浓度削减50%~60%,可满足不同用途对砖的标准要求.研究显示,在不同抗压强度的要求下选取适当的配比与养护条件,可以达到炉渣消纳量大且能源耗费少的目的,并削减水溶性氯离子含量与重金属浸出浓度,具有环保效益.      

流化床锅炉飞灰生产砌筑水泥的试验研究

循环流化床锅炉燃烧技术是近年来国内外竞相发展的洁净燃烧技术 ,但流化床锅炉排放的大量飞灰 ,目前还没有成熟的处理方法。本研究介绍了对该飞灰的活性进行激发 ,并利用其生产砌筑水泥的试验研究。     

水洗过程对垃圾焚烧飞灰浸出特性的影响

通过水洗试验,对垃圾焚烧飞灰的浸出特性进行了研究.结果表明:水洗过程对飞灰中Cl,Na,K和Ca元素具有一定的去除效果,尤其是Cl元素的去除率在液固比为10 L/kg时可达到60.0%;经过水洗后飞灰XRD图中的钾盐和食盐的特征峰已经不明显,石英和石膏特征峰改变很小,KCl和NaCl是水洗过程中K,Na和Cl元素的主要去除形态;水洗对飞灰的酸中和容量影响较小;采用TCLP法和水平振荡法进行对比试验表明,水洗灰的重金属浸出质量浓度均低于原灰.      

基于固化法共处置飞灰和浓缩液浸出特性研究

在水泥固化时将生活垃圾焚烧飞灰（简称飞灰）以不同的比例代替复合硅酸盐水泥并且用垃圾渗滤液浓缩液代替水进行固化实验,研究了飞灰掺量（40%、50%、60%）、浓缩液替代水对水泥固化法固化效果及重金属（Zn、Pb、Cd、Cr、As、Ba）浸出的影响.结果表明：飞灰掺入量的增加会降低固化体的抗压强度,但浓缩液替代水对固化体的抗压强度没有显著影响.不同重金属的浸出行为受掺灰率的影响不同,掺灰率的增加会减少固化体中Zn的浸出,增加Pb和Cd的浸出,Zn、Pb、Cr、As在第36d可达到稳定浸出量不再增加,Ba的累积浸出量持续增加,加入浓缩液后固化体中Pb、Zn、Cd、Cr、As等重金属的浸出量未超过标准限值,可以满足固化处理对浸出毒性的要求.     

电解锰矿渣制备免烧砖的试验研究

以电解锰渣、粉煤灰、石灰、水泥、砂为原料,经配方设计,制备了电解锰矿渣免烧砖,在洒水养护28天后,其抗压强度可保持在10MPa以上。研究表明,随着电解锰渣含量的减少,其锰渣砖抗压强度逐渐增强。原料的适宜配比为:电解锰渣40%、粉煤灰40%、生石灰10%、水泥10%,胶砂比为1.0,水固比为0.10。     

生活垃圾循环流化床焚烧锅炉飞灰中二噁英热解析特性研究

实际垃圾焚烧系统中飞灰会在尾部烟道堆积并在受热后发生二噁英的再生成、热降解及向烟气解析等协同作用.本文研究了半干法脱硫塔前生活垃圾焚烧飞灰在受热过程中二噁英的质量变化及其气固相分布情况,重点研究了反应温度、含氧量及硫胺基复合阻滞剂的添加等对飞灰中二噁英热解析特性的影响.试验结果表明,250℃时飞灰析出的气相二噁英很少,而450℃时气相二噁英的比例高达99.7%;氧含量对飞灰中二噁英的热解析特性影响较大,当氧含量为6%时,气相二噁英的析出量最大,达到2.87 ng·g-1;350℃时添加硫胺基复合阻滞剂后二噁英总量明显下降,表明阻滞剂能够抑制二噁英再合成,但气相中二噁英的比例从47.69%上升到87.50%.     

垃圾焚烧飞灰物理化学性质的实验研究

应用激光粒度粒形分析仪、灰熔融性测定仪、原子吸收光谱仪和XRD等仪器手段对国内2种垃圾焚烧飞灰的密度、颗粒特性、熔点、成分和晶相结构等物理化学性质进行了详细的研究。研究发现，2种灰样颗粒直径的数量积分分布非常接近，其中基本没有超过40／μm的颗粒。由于垃圾焚烧飞灰在化学成分上存在的差异导致了其熔点有很大的不同。此外，XRD结果显示不同来源的飞灰其晶相结构存在较大的差别，这可能与垃圾的来源和焚烧工艺以及烟气处理方法有关。实验结果为飞灰无害化低温烧结工艺的选择和运行参数的制定提供了依据。     

Chemical speciation and mobility of heavy metals in municipal solid waste incinerator fly ash

Chemical speciation is a significant factor that govems the toxicity and mobility of heavy metals in municipal solid waste incinerator fly ash. Sequential extraction procedure is applied to fractionate heavy metals( Pb, Zn, Cd, Cu, and Cr) into five defined groups: exchangeable, carbonate, Fe-Mn oxide, organic, and residual fractions. The mobility of heavy metals is also investigated with the aid of toxicity characteristic leaching procedure. In the fly ash sample, Pb is primarily presented in the carbonate (51%) and exchangeable(20% ) fractions; Cd and Zn mainly exist as the exchangeable(83% and 49% respectively) ; Cu is mostly contained in the last three fractions(totally 87% ) ; and Cr is mainly contained in the residual fraction(62% ). Pb, Zn and Cd showed the high mobility in the investigation, thus might be of risk to the natural environment when municipal solid waste incinerator fly ash is landfilled or reutilized.     

生活垃圾焚烧飞灰的加速碳酸化处理

针对垃圾焚烧飞灰中钙及两性重金属含量高的特点,在高液固比(10:1)条件下对焚烧飞灰进行加速碳酸化处理以改善飞灰的理化特性.采用XRD、SEM、压汞分析以及硫酸硝酸毒性浸出方法,对加速碳酸化处理后飞灰的晶相、形貌、孔隙特征及重金属(Pb、Cu、Zn、Cd、Ni、Cr)浸出特性进行了研究.结果表明,加速碳酸化处理后飞灰中的CaClOH峰消失,而CaCO3的峰增加,且强度增加.加速碳酸化处理可以有效降低焚烧飞灰的pH值, Pb、Cu、Zn和Ni的浸出分别减少了99.7%、93.9%、90.6%和27.8%,而Cr的浸出浓度增加了29.7%.     

城市生活垃圾焚烧飞灰中钾盐浸出研究

通过物理化学表征手段和多因素水浸试验对城市生活垃圾焚烧飞灰的性质和飞灰中钾盐浸出规律进行研究.结果表明,飞灰的主要成分为CaO、KCl和NaCl,平均粒径为12.599μm,水洗后的飞灰颗粒粒径会变大,而比表面积变小.粒径范围0.037~0.075 mm飞灰中的金属元素含量对飞灰金属总量贡献率全部在60%左右.浸出过程中,在pH=12的条件下,搅拌强度为400 r·min~(-1),浸出温度为90℃,采用液固质量比为5∶1能使氯化钾的浸出率达到90%以上.浸出液中含有大量的可溶性氯化钾表明飞灰中的钾盐可以通过水洗、过滤、纯化、分布结晶的方式收,氯化钾晶体纯度可达到90%.     

垃圾焚烧飞灰冶金性能研究

垃圾焚烧飞灰是危险废物因而必须进行处理.用冶金高温熔融分离来处理飞灰是一个新的无害化处理方法.在了解飞灰特性的基础上,研究了飞灰的冶金性能.对飞灰进行冷固结造球,并分析了球团的强度和浸出毒性;测试了球团的粘度和熔化性温度;进行了飞灰球团高温熔融分离实验,分析了熔渣中的重金属和浸出毒性.实验结果表明,飞灰的矿物组成主要是CaO、SiO2等氧化物;选择7%消石灰,添加1%糖浆进行飞灰冷固结,并养护18d,单个球团平均抗压强度可达到1005 N,球团的浸出毒性没有超标.飞灰的熔化性温度范围为1250～1290℃,此时的熔渣粘度较低;飞灰高温熔融分离的适宜工艺参数为:熔融温度1400℃,熔融时问10min,球团碱度1.8,金属熔池与飞灰球团配比为5:4,金属熔融分离效果很好;飞灰经过1300℃以上的高温熔融,熔渣远远低于浸出毒性标准.     

Characterization of mechanochemical treated fly ash from a medical waste incinerator

The mechanochemical treatment of fly ash generated from a medical waste incinerator was subjected to grinding for 2 hr at 400 r/min in a planetary ball mill. The treated fly ash was characterized by a suite of analytical methods including High Resolution Gas Chromatograph/High Resolution Mass Spectrometer, Mastersizer 2000 Particle Size Analyzer, QUADRASORBTM SI Surface Area Analyzer, Scanning Electron Microscopy and X-ray di raction. Results showed that abatement e ciency of polychlorinated dibenzop- dioxins and polychlorinated dibenzofurans (PCDDs/Fs) in terms of total concentration averagely amount to 76% which was relatively higher than that of I-TEQ concentration averagely amount to 56%; the most concentration of toxic congeners as well as isomers of PCDDs/Fs decreased after mechanochemical treatment. The treated fly ash was characterized by a more homogeneous distribution of concaves as well as the significant decreasing in overall particle size and great enlargement in surface area. The major crystallization phases or intensities were considerably changed by mechanochemical treatment, of which a new phase containing chlorine formed may be a possible factor suggesting chlorination reaction occurring on the crystalline surface.     

Experimental investigation of ash deposits on convection heating surfaces of a circulating fluidized bed municipal solid waste incinerator

Incineration of municipal solid waste(MSW) is a waste treatment method which can be sustainable in terms of waste volume reduction, as well as a source of renewable energy.During MSW combustion, increased formation of deposits on convection heating exchanger surfaces can pose severe operational problems, such as fouling, slagging and corrosion.These problems can cause lower heat transfer efficiency from the hot flue gas to the working fluid inside the tubes. A study was performed where experiments were carried out to examine the ash deposition characteristics in a full-scale MSW circulating fluidized bed(CFB) incinerator, using a newly designed deposit probe that was fitted with six thermocouples and four removable half rings. The influence of probe exposure time and probe surface temperature(500, 560, and 700℃) on ash deposit formation rate was investigated. The results indicate that the deposition mass and collection efficiency achieve a minimum at the probe surface temperature of 560℃. Ash particles are deposited on both the windward and leeward sides of the probe by impacting and thermophoretic/condensation behavior. The major inorganic elements present in the ash deposits are Ca,Al and Si. Compared to ash deposits formed on the leeward side of the probe,windward-side ash deposits contain relatively higher Ca and S concentrations, but lower levels of Al and Si. Among all cases at different surface temperatures, the differences in elemental composition of the ash deposits from the leeward side are insignificant.However, as the surface temperature increases, the concentrations of Al, Si, K and Na in the windward-side ash deposits increase, but the Ca concentration is reduced. Finally,governing mechanisms are proposed on the basis of the experimental data, such as deposit morphology, elemental composition and thermodynamic calculations.     

Leaching characteristics of heavy metals during cement stabilization of fly ash from municipal solid waste incinerators

The leaching characteristics of heavy metals in products of cement stabilization of fly ash from a municipal solid waste incinerator were investigated in this paper. The stabilization of heavy metals such as Cd, Pb, Cu, and Zn in fly ash from such incinerators was examined through the national standard method in China based on the following factors: additive quantity of cement and Na₂S, curing time, and pH of leaching liquor. The results showed that as more additives were used, less heavy metals were leached except for Pb, which is sensitive to pH of the leachate, and the worse effect was observed for Cd. The mass ratio of cement to fly ash = 10% is the most appropriate parameter according to the national standard method. When the hydration of cement was basically finished, stabilization of heavy metals did not vary after curing for 1 d. The mixtures of cement and fly ash had excellent adaptability to environmental pH. The pH of leachate was maintained at 7 when pH of leaching liquor varied from 3 to 11. __________ Translated from Environmental Science, 2006, 27(12): 2564–2569 [译自: 环境科学]     

Effects of inorganic chlorine source on dioxin formation using fly ash from a fluidized bed incinerator

Chlorine source is indispensable for polychlorinated dibenzo-p-dioxin and furan (PCDD/F) formation during municipal solid waste (MSW) incineration. Inorganic chlorine compounds were employed in this study to investigate their effects on PCDD/F formation through heterogeneous synthesis on fly ash surfaces. A fly ash sample obtained from a fluidized bed incinerator was sieved to different size fractions which served as the PCDD/F formation sources. The capability of different metal chlorides which facilitate the formation of PCDDs/Fs was found to follow the trends: Na ＜ Mg ＜ K ＜ Al ＜ Ca, when two particle fractions of ＞177 μm and 104-125 μm were used in the experiments. However, the capability of NaCl, MgCl2 and KCl did not seem much different from each other, whereas CaCl2 and AlCl3 were much more active in PCDD/F formation. NaCl and MgCl2 were relatively effective to produce more PCDDs, while KCl, AlCl3 and CaCl2 generated more PCDFs during heterogeneous reactions occurring on fly ash. 2,3,7,8-TCDF was the most significant contributor to the toxicity of the PCDDs/Fs formed from inorganic chlorine sources. Decreasing the sizes of fly ash particles led to more active formation of PCDDs/Fs when NaCl was used as inorganic chlorine in the experiment. The highest PCDDs/Fs produced from particles with size ＜37 μm, while the lowest PCDDs/Fs produced from particles with size ＞177 μm. The toxicity generally increased with decreasing size of the fly ash particles. The formation of PCDDs was mainly facilitated by the two size fractions, 104-125 μm and ＜37 μm, while formation of PCDFs was favored by the two other size fractions, ＞177 μm and 53-104 μm.