CaO-SiO2-FeO体系中选择性分离锌铅的实验研究

为了探讨CaO-SiO2-FeO体系中选择性分离回收Zn, Pb的可行性,在系统分析该体系中Zn, Pb挥发行为的基础上,研究了温度、基体成分及Cl含量等因素如对Zn, Pb挥发率的影响. 结果表明,低温、低碱度、低FeO含量、低Cl含量条件下,Zn与Pb的挥发率差异达到最大,原因在于该种条件下Zn倾向于以ZnFe2O4等复杂化合物形式滞留在渣基体中,而Pb以氯化物形式挥发;在此基础上,对实验后的渣基体进行升温、并添加一定量的C粉等还原剂后,渣中Zn会以单质形式挥发分离,从而实现粉尘及飞灰熔融处理过程中Zn、Pb的选择性分离回收.     

医疗垃圾焚烧飞灰中重金属的蒸发特性

利用管式高温炉研究了医疗垃圾焚烧飞灰中重金属的蒸发特性,以确定飞灰中重金属的有效热分离参数. 结果表明,停留时间20与60 min时的重金属蒸发率差别不大,其影响程度取决于温度;布袋飞灰中高含量Cl的存在对重金属的蒸发有促进作用;在1000℃时,飞灰中Pb和Cd的蒸发率已达90%以上;气氛对Zn的蒸发效果影响显著,Zn在1000℃空气气氛下蒸发率仅为67%,但在N2气氛下蒸发率高达92%;若考虑Cd, Pb, Zn等挥发性重金属有效分离和二噁英分解两方面的需求,医疗垃圾焚烧飞灰的最低热处理温度宜控制在1000℃左右.     

生物质与煤混烧时PM10中痕量元素分布的研究

选取两种典型生物质与两种煤,将两种生物质与两种煤按质量百分比为1：3分别进行混合,得到4种燃料,然后分别在l150℃,N／O比l：1和4：1两种气氛下在沉降炉上进行实验,研究了混烧产生的PM10中4种部分挥发性痕量元素（Mn,Pb,Zn和Cr）的分布行为．结果表明：S,Cl和N／O比对Mn的挥发性影响均很小,Cl对Pb和Zn的挥发行为有促进作用,S则相反．而S,Cl对Cr的挥发行为均有抑制作用．N／O比变化对Cr元素的影响最为明显,而对Mn,Pb和Zn的影响均不大,N／O比减小有助于Cr挥发性的增强．     

电弧炉熔融医疗垃圾焚烧灰的实验研究

利用处理量为2 kg的直流电弧炉对医疗垃圾焚烧的底灰、底灰与布袋飞灰的混合灰分别进行熔融实验研究,并比较了熔融前后灰和熔渣的化学成分、物相、微观形貌、浸出毒性及重金属残留率. 结果表明,底灰主要由复杂的硅酸盐晶体组成,布袋飞灰含有大量的硬石膏(CaSO4)、氯化钠(NaCl)晶体,熔融后两种熔渣均为无定形非晶态的玻璃熔岩. 底灰、混合灰熔融后减容率分别达到78%和80.5%;熔融前布袋飞灰浸出液中Pb, Cd, Zn浓度远超过危险废物填埋限值,熔融后的熔渣中重金属固化在Si-O网格中,渗沥液中浓度极低,完全符合环保要求. 熔融后2种熔渣中Pb, Cd, Zn的残留率较低,而且混合灰熔渣中重金属残留率均低于底灰熔渣.     

水泥窑炉协同处置垃圾焚烧飞灰过程中重金属挥发特性研究

研究了水泥窑炉协同处置垃圾焚烧飞灰过程中重金属挥发特性,探讨了水泥工业协同处置城市生活垃圾焚烧飞灰的技术及其可行性。研究结果表明,飞灰中重金属挥发率随着煅烧温度的升高而升高;在水泥高率值配方条件下飞灰的重金属挥发率要高于在低率值配方条件下的挥发率;重金属元素中Mn、Cr、Zn、Cu的挥发率相对较低,1 450℃以下挥发率大多小于40%;Pb、Cd的挥发率相对较高,在1 450℃挥发率可达到90%~100%。水泥矿物对重金属元素中Mn、Cr、Zn、Cu的固化效果较好,对Ba、Pb、Cd的固化效果较差,因此在水泥生产过程中应加强粉尘回收,防止造成环境污染。     

添加剂对污泥焚烧过程中重金属迁移特性的影响

利用管式炉研究了Cl、S、P对重金属迁移特性的影响,研究结果表明：C促进了重金属Cd、Pb、Zn、Cu的挥发,而对重金属Ni、Cr的挥发特性影响不大;S对重金属的挥发特性影响不大,在一定程度上抑制霞金属Zn、Cd、Ni的挥发,而对重金属Pb则促进其挥发;P对不同重金属的挥发特性影响不同,随着P含量的增加,重金属Cr和Ni的挥发的挥发率逐渐增大,而重金属Cd、Pb和Zn的挥发率逐渐降低。     

土壤聚合物固化飞灰与水泥固化的比较研究

本文分析了焚烧飞灰的主要化学组成,对土聚物固化城市垃圾焚烧飞灰和水泥固化飞灰的效果进行了实验研究和比较,探讨了土壤聚合物固化垃圾焚烧飞灰的机理.结果表明,焚烧飞灰主要包括Ca、Cl、Si、Al、K、S、Na等,重金属包括Zn、Pb、Cu、Cd和Cr等.在相同的条件下,土聚物固化飞灰后固化体的抗压强度明显高于水泥固化体,且表现出早期抗压强度高的特点,固化体重金属的浸出毒性远低于国家有关浸出毒性标准.     

混合飞灰熔融对灰熔融炉用耐火材料损毁的影响

介绍了处理城市垃圾焚烧炉焚烧灰和飞灰用灰熔融炉及其耐火材料的损毁机理，灰熔融炉用耐火材料的损毁主要是在接触高碱度炉渣部位和接触飞灰发生气体部位，在还原气氛和强氧化气氛下，一般使用SiC砖，C－SiC砖和Al2O3-SiC砖。在氧化气氛下，一般使用MgO-Cr2O3砖，Al2O3-Cr2O3砖和Al2O3-Cr2O3-ZrO2砖，另外，在灰熔融炉炉盖部位通常使用水泥结合浇注料和化学浇注料，但化学结合浇注料的性能比水泥结合浇注料好。     

垃圾焚烧飞灰熔融过程中重金属挥发特性研究进展

熔融固化技术具有减容化、无害化和资源化的优点，被认为是目前最稳定、最安全的垃圾焚烧飞灰处理方法。但飞灰熔融过程中，低沸点的重金属易挥发至气相产生二次飞灰，造成二次污染。概述了垃圾焚烧飞灰组成和重金属含量、熔融过程中重金属挥发影响因素、飞灰熔融特性的调控等，为飞灰熔融固化过程中抑制重金属的挥发提供思路。     

Friedel盐对废水中低浓度Cd2+的吸附动力学

以合成的Friedel盐(FS, 3CaO×A12O3×CaCl2×10H2O)为吸附剂,研究了FS去除废水中Cd2+的反应动力学和等温吸附特性. 考察了FS盐用量、温度及Cd2+初始浓度对Cd2+去除的影响. 结果表明,FS用量为0.03 g/L时,在室温下对废水中初始浓度为10 mg/L的Cd2+的去除率大于94.34%,吸附容量可达301.9 mg/g,吸附主要以离子交换吸附为主,最终形成Cd4Al2(OH)12Cl2(H2O)4×xH2O及Cd4Al2(OH)12Cl2×4H2O化合物. 利用一级动力学模型关联了反应动力学数据,得到速率常数k=0.049 min-1,吸附行为较符合Langmuir等温吸附方程.     

High Temperature Interactions Between Residual Oil Ash and Dispersed Kaolinite Powders

The potential use of sorbents to manage ultrafine ash aerosol emissions from residual oil combustion was investigated using a downfired 82 kW laboratory-scale refractory-lined combustor. The major constituents were vanadium (V), nickel (Ni), iron (Fe), and zinc (Zn). The overall ash content of residual oil is very low, resulting in total ash vaporization at 1725 K with appreciable vaporization occurring at temperatures as low as 1400 K. Therefore, the possibility of interactions between ash vapor and sorbent substrates exists. Kaolinite powder was injected at various locations in the combustor. Ash scavenging was determined from particle size distributions (PSDs) measured by a Scanning Mobility Particle Sizer. Impactor samples and X-ray fluorescence (XRF) analyses supported these data. Injection of kaolinite sorbent was able to capture up to 60% of all the ash in the residual fuel oil. However, captures of ～ 30% were more common when sorbent injection occurred downstream of the combustion zone, rather than with the combustion air into the main flame. Without sorbent addition, baseline measurements of the fly ash PSD and chemical composition indicate that under the practical combustion conditions examined here, essentially all of the metals contained in the residual oil form ultrafine particles (～0.1 μ m diameter). Theoretical calculations showed that coagulation between the oil ash nuclei and the kaolinite sorbent could account for, at most, 17% of the metal capture which was always less than that measured. The data suggest that kaolinite powders reactively capture a portion of the vapor phase metals. Mechanisms and rates still remain to be quantified.     

Heterogeneous oxidation of mercury in simulated post combustion conditions

Heterogeneous mercury oxidation was studied by exposing whole fly ash samples and magnetic, nonmagnetic, and size-classified fly ash fractions to elemental mercury vapor in simulated flue gas streams. Fly ash from sub-bituminous Wyodak-Anderson PRB coal and bituminous Blacksville coal were used. Scanning electron microscopy, X-ray diffraction, thermogravimetric analyses, and BET N₂ isothermal sorption analyses were performed to characterize the fly ash samples. Mercury speciation downstream from the ash was determined using the Ontario Hydro method. Results showed that the presence of fly ash was critical for mercury oxidation, and the surface area of the ash appears to be an important parameter. However, for a given fly ash, there were generally no major differences in catalytic oxidation potential between different fly ash fractions. This includes fractions enriched in unburned carbon and iron oxides. The presence of NO₂, HCl, and SO₂ resulted in greater levels of mercury oxidation, while NO inhibited mercury oxidation. The gas matrix affected mercury oxidation more than the fly ash composition.     

六盘水粉煤灰理化性质分析及资源化利用途径

为充分利用六盘水地区火电厂的粉煤灰,采用XRF、XRD、FT-IR等现代分析手段研究了粉煤灰的理化性质,结果显示：六盘水地区的粉煤灰主要以莫来石和少量石英组成,其中二氧化硅、三氧化二铝和三氧化二铁质量分数约为80%,属于高硅、高铁、低铝型。结合六盘水地区粉煤灰的资源化利用现状,针对其形貌结构和组成特点,提出适宜六盘水地区粉煤灰精细化、高附加值综合利用的可持续发展路径。     

钙对粉煤灰基土聚水泥性能的影响研究

采用正交试验优化设计制备了粉煤灰基土聚水泥,并进一步研究了钙对粉煤灰基土聚水泥性能的影响。研究表明：硅铝比是影响粉煤灰基土聚水泥强度发展的重要因素,碱铝比次之,水碱比最小;土聚水泥的最佳配比为硅铝比4.6,碱铝比0.8-1.1,水碱比6.0-7.2;不同种类以及掺量的钙质组分对土聚水泥的强度发展影响很大,体系中的钙应控制在适宜范围。     

烧结法提取粉煤灰中氧化铝的新进展

在简述了粉煤灰的理化性能及矿物组成后,根据破坏粉煤灰中SiO2-Al2O3键及活化Al2O3的不同方式对提取粉煤灰中氧化铝的技术进行了分类,然后总结国内近十年来在烧结法提取粉煤灰中氧化铝方面取得研究新进展,并简要地评述了不同烧结法提取氧化铝工艺的优缺点,并展望了今后烧结法提取粉煤灰中氧化铝的研究方向。     

Ash Vaporization and Condensation During Combustion of a Suspended Coal Particle

The results of a theoretical study of the formation and growth of the submicron flyash aerosol around a single burning coal particle are presented. The vaporization of ash and subsequent aerosol formation near the coal particle are studied because the local combustion environment influences these processes strongly. A mathematical model is developed that describes the transport of ash vapor and and the growth of the aerosol. The ash aerosol calculation is superimposed on an existing solution to the combustion problem. Included in the model are the effects of convective transport and of both homogeneous and heterogeneous condensation of the ash vapor. The results of the calculations show that refractory compounds with low surface tension, like silica, nucleate very near the coal particle's surface and produce a substantial mass loading of aerosol. The presence of the aerosol does not greatly affect the ash vaporization rate, which is primarily a function of combustion conditions. The size and amount of the submicron ash aerosol are determined by both the local combustion conditions and the ash's physical properties.     

粉煤灰催化H_2O_2氧化CN~-的研究

介绍了利用电厂粉煤灰作为催化剂 ,催化 H2 O2 氧化 CN-的研究情况 ,讨论了各种因素对 CN-去除率的影响。结果表明 ,粉煤灰具有良好的催化活性 ,能有效地催化 H2 O2 氧化 CN- 。该法可用于处理电镀、制革、焦化行业含 CN- 的工业废水 ,具有广阔的应用前景。     

The fate of sodium during pulverized coal combustion

The distribution of sodium in the different sizes of fly ash produced during coal combustion provides useful insights into the vaporization and condensation mechanisms for sodium. For the residual fly ash, the departure of the concentration of sodium from an inverse square dependence on particle size can be used to infer the degree of sodium vaporization. For low-rank coals most of the sodium vaporizes at combustion temperatures <1900 K; at higher temperatures the release of sodium decreases as increasing amounts react with silica. The fraction of sodium condensing on the submicrometre fume is influenced both by the amount of total ash vaporized and by the Kelvin effect.     

景德镇电厂粉煤灰的理化性质分析与表征

粉煤灰是烧煤发电后产生的一种工业废渣。本文采用Mastersizer2000型激光粒度分析仪、DSC/TG、XRD与SEM等测试手段,对景德镇电厂粉煤灰的理化性质进行了分析和表征。结果表明:景德镇电厂粉煤灰是由平均粒径大小为31.5μm的细微颗粒组成,粒度主要分布在1～100μm;其化学成分主要为SiO2、A12O3与Fe2O3,三者总含量高达84.4%,其次是MgO、K2O、CaO、Na2O;其物相成分主要有石英、莫来石、赤铁矿与玻璃相。