掺超细循环流化床粉煤灰的水泥性能试验研究

通过对新拌水泥浆体的流变特性和水泥胶砂强度的测定,结合MIP与SEM等微观测试手段,研究了超细循环流化床粉煤灰(UCFA)对不同掺量循环流化床粉煤灰(CFA)水泥物理性能和力学性能的影响。结果表明:单掺CFA水泥的需水量较大,流动性差,强度下降明显;而用5%UCFA(最佳掺量)部分替代CFA,相比于单掺CFA水泥,需水量相应减少,流动度增加,水泥浆体的屈服应力τ₀和塑性黏度η值均有所减小,浆体的工作性能得到明显改善。30%粉煤灰掺量的水泥3 d强度提高6%;60%粉煤灰掺量的水泥28 d强度提高5%,达到32.5等级水泥要求;UCFA的掺入能够促进CFA水泥生成更多的钙矾石和C-S-H凝胶,改善硬化水泥浆体的孔隙结构,提高水泥强度。     

粉煤灰制备抗盐卤水泥的研究

基于熟料-矿渣-粉煤灰复合胶凝体系的抗盐卤水泥是在水泥熟料制备时采用低品质粉煤灰作原料生产含硅酸三钙和无水硫铝酸钙相的熟料,研究了在水泥配制时采用细磨的Ⅱ级粉煤灰作活性混合材,生产大掺量混合材的复合水泥。研究表明,这种水泥具有早强、高强、抗蚀等特点,适于盐湖地区恶劣环境下的工程建设。     

Chloride transport and its sensitivities to different boundary conditions in reclaimed soil solutions filled with fly ash

Chloride ion transport in reclaimed soil solutions filled with fly ash (FA) was investigated by measuring the hydraulic parameters (i.e. water retention curves and hydraulic conductivity) of three substrates, namely GSL, GFA, and CFA. Similar simulations were carried out under certain weather conditions. The different boundary conditions of chloride transport were also discussed from FA texture, cover soil thickness, groundwater table level, and initial chloride concentration. Furthermore, the sensitivities of chloride ions to these effect factors were analyzed. The results show that the different top soil thickness and initial chloride concentration have no effect on salinity of topsoil solution in the monitoring points, but they can clearly change the chloride concentration of FA layers. The sensibilities from top soil thickness and initial chloride content are exceedingly weak to the salinity balance based on two dimensions of the time and concentration. While the different FA texture and groundwater table not only affect the salinity equilibrium process of the whole reclaimed soil profile, but also change its balance state. Generally, coarse FA particles and high groundwater table can defer the salinity balance process of the reclaimed soil solution, and they also increase the chloride concentration of FA layer solutions, and even topsoil ones.     

碳热还原粉煤灰物相变化规律

在感应炉中,空气气氛下,以粉煤灰为原料,木炭为还原剂,不同温度条件下对粉煤灰还原反应过程及合金进行研究。利用XRD,SEM-EDS技术对还原产物进行分析检测。结果表明,碳还原粉煤灰分为4个阶段：（1 373～1 673 K）Fe2O3和碳反应生成铁;（1 773～1 873 K）石英和碳反应生成SiC,莫来石发生分解并与碳反应生成SiC和Al2O3;（1 973～2 173 K）石英除生成较多SiC,还有少量Si生成,部分Al2O3和空气中的氮气生成Al5O6N,并最终分解成Al2O3和AlN;2 273 K氧化铝和SiC,C反应生成Al,Si,AlN和碳反应生成Al。高温下有气态的SiO,Al2O产生,造成部分铝硅损失。合金由3个相组成,3者相互混合存在,除含有较多Al,Si,Fe,Ca外,还含有部分SiC。在合适的配碳量下,Al2O3对SiC的生成有抑制作用。     

粉煤灰的环境特性

论述了粉煤灰中有害物质及其对环境产生危害的途径和粉煤灰危害性的特点，分析了粉煤灰的淋溶性、粉煤灰微量元素农作物吸收性和粉煤灰的放射性，认为粉煤灰总体上对环境不会产生严重危害，但粉煤灰存在环境危害性也是不争的事实．总结了当前粉煤灰环境特性研究状况，指出了研究过程中存在的主要问题，认为将粉煤灰利用研究与粉煤灰环境特性研究结合起来是粉煤灰综合利用的必由之路和发展方向．     

基于人工神经网络的粉煤灰科学分类

针对目前国内粉煤灰分类的片面性，结合人工神经网络理论，提出了基于人工神经网络的粉煤灰科学分类．该方法充分考虑了粉煤灰的火山灰活性，并考虑了细度、玻璃体、烧失量、K2O、SO3和CaO多种因素对分类的影响．实例表明，按本文提出方法建立的网络模型较合理，且其精度也较高，克服了以往分类法的片面性，较全面地反映了粉煤灰的品质性能，从而为粉煤灰的多元化利用奠定基础．     

Properties of fly ash stabilized haul road construction materials

ABSTRACT

Larger haul trucks are being used at surface mines in Canada thus requiring better haul roads to carry heavier loads. The availability of good quality aggregate to build haul roads is limited for prairie coal mines. However, most of these mines are located adjacent to coal-fired electrical power plants, which produce by-product fly ash as a waste. Fly ash can be used to increase strength and stiffness of soil and road bases.

Unconfined compressive strength tests conducted on various mixtures of fly ash, kiln dust, mine spoil, and coal seam partings showed that the cementing characteristics of unclassified fly ash from central Alberta coals was low. However, the addition of cement kiln dust, which is high in CaO, enabled the fly ash to exhibit significant cementing action.

Mixtures of fly ash, kiln dust, and mine spoil or coal seam partings had unconfined compressive strengths of about 1 MPa and elastic moduli of about 350 MPa after 14 to 28 days. This compares favourably with compacted mine spoil or coal seam partings which have estimated unconfined compressive strengths of less than 0.4 MPa and moduli of about 50 MPa. Thus fly ash stabilized mine spoil or coal seam partings were found to have potential for use in constructing haul road base and sub-base layers since maximum tire pressures on the running surface are less than 0.7 MPa.     

粉煤灰中灰颗粒的摩擦带电特征

利用电位差计配合法拉第圆筒测量2种材料的摩擦电势差及电性符号,对10种材料进行了摩擦带电研究,确定了它们的摩擦静电序列为Pb,Zn,Al,Fe,C,Mn,Cu,SiC,Ag,粉煤灰;选出了Mn,Cu,SiC,Ag 四种作为粉煤灰摩擦带电电选机的荷电摩擦材料.用0.5 MPa除水压缩空气在铁管中进行气力输送摩擦带电试验,研究了气体流速、管道形式和长度、以及摩擦管道内固气比等因素对粉煤灰摩擦带电量的影响,增大气体流速能显著提高粉煤灰的带电量,而管道长度对灰颗粒的荷质比影响不大.     

粉煤灰理化性能研究

利用化学及工业分析、X射线衍射分析、扫描电镜等手段,对蒲白、秦岭和灞桥3个电厂的粉煤灰样品进行分析.根据粉煤灰的物理化学性质、微观特征及其他测试指标,参考国家有关标准和文献,对粉煤灰的类型进行了判断,并指出粉煤灰的特点及综合利用途径.     

粉煤灰处理及资源利用

粉煤灰是在煤燃烧后的烟气中收集的细灰,是燃煤电厂的主要固体废弃物。如何利用好粉煤灰,减少其对环境的污染等已成为我国经济建设的主要问题之一。文章阐述了粉煤灰的密度、粒径等物理性质,以及粉煤灰的主要组分。从环境保护和绿色可持续发展的角度,分别介绍了生产加入粉煤灰的混凝土和烧结砖等建筑材料,从粉煤灰中提取金属氧化物,处理废气废水和修复土壤等方面的应用。并同时针对结合我国粉煤灰的利用情况和政策现状,对粉煤灰其利用将来的利用和发展进行了讨论。     

粉煤灰综合利用新途径的探讨

以工业废渣粉煤灰作为原材料,掺加碱性激发剂所制备的碱激发粉煤灰材料,具有良好的耐酸性、耐热性、耐硫酸盐腐蚀及低收缩率等特性,采用高温蒸汽养护可以快速提高早期强度.     

化学激发粉煤灰活性机理研究进展

综述了近10 a来用化学方法激发粉煤灰活性的机理研究进展,认为粉煤灰活性化学激发有3个基本思路：一是“补钙”,提高水化体系的CaO/ SiO2比;二是破坏玻璃体表面光滑致密、牢固的Si-O-Si和Si-O-A1网络结构;三是激发生成具有增强作用的水化产物或促进水化反应.激发粉煤灰活性的激发剂主要是硫酸盐和强碱,而氯盐则较少;在相同条件下,氯盐的激发效果不及硫酸盐和强碱;激发剂的复合使用已成为粉煤灰化学激发的趋势.另外,就粉煤灰活性激发研究中存在的问题提出了几点看法.     

Ferrovanadium production from petroleum fly ash and BOF flue dust

Fly ash is generated as a solid residue in the power plant using crude oil and petroleum coke as fuels, and contains significant amount of vanadium. To utilize the industrial wastes, a better processing route is to convert environmentally hazardous wastes that have no or limited market value into products or intermediate products with added market value. In the present study a recipe-based concept is introduced and metal recovery from a selected waste mixture is investigated in the lab-scale experiments. Two waste ash residues of BOF steelmaking flue dust and petroleum fly ash are used as raw materials, and the residue carbon from the fly ash is used as reducing agent. The ferrovanadium with about 20 wt.% vanadium is obtained. This proves that a recipe-based waste processing can be a sustainable option for the future waste management.     

粉煤灰制多孔玻璃微珠

摘要：以电厂的废弃物粉煤灰为原料,研究了1273K温度下,粉煤灰和添加剂粉末制得了孔隙率较高的多孔玻璃微珠的过程。并对其吸附性能做了初步研究。用氮吸附静态容量法,测得该多孔玻璃微珠的氮吸附等温线、比表面和孔分布曲线。探讨了多孔玻璃微珠吸附特性和成珠条件。     

Influence of NaOH solution on the synthesis of fly ash geopolymer

A study was conducted on leaching of fly ash mixed with NaOH solution and on mixing procedure for preparing geopolymer. Leaching of SiO₂ and Al₂O₃ was investigated by mixing fly ash with NaOH solution for different time intervals and leachates were analyzed in terms of silica and alumina contents. To make geopolymer paste, separate mixing and normal mixing were used. For separate mixing, NaOH solution was mixed with fly ash for the first 10 min; subsequently sodium silicate solution was added into the mixture. For normal mixing, fly ash, sodium hydroxide and sodium silicate solution were incorporated and mixed at the same time. Geopolymers were cured at 65 °C for 48 h. Microstructure of paste and compressive strength of mortar were investigated. Results revealed that solubility of fly ash depended on concentration of NaOH and duration of mixing with NaOH. For mixing procedure, separate mixing gave slightly better strength mortar than normal mixing. High strength geopolymer mortar up to 70.0 MPa was obtained when the mixture was formulated with 10 M NaOH and sodium silicate to NaOH ratio of 1.0, and the separate mixing sequence was used.     

利用粉煤灰合成沸石的方法研究

通过分析粉煤灰的矿物组成、化学成分和合成方法,指出水热法制备沸石是最佳的方法,指出现行水热合成法中的一步法和两步法存在的主要问题,提出了提高水热合成效果的措施,为粉煤灰合成高品质沸石提供了借鉴。     

粉煤灰浮选除炭技术优化

通过各种条件下浮选和联合浮选试验,表明二段开路浮选流程分高除炭效果明显优于常规一段浮选分选系统,具有入料适应性好、分选精度和产率均高于常规一段浮选的优点,是解决目前高炭粉煤灰综合利用“瓶颈问题”的有效途径。     

循环流化床锅炉飞灰的分形特性

为分析循环流化床飞灰的微观特性,以某480 t/h循环流化床锅炉为研究对象,通过压汞仪和扫描电镜研究其飞灰的分形特性。研究结果表明,循环流化床锅炉飞灰含碳量随粒径的分布具有峰值特性,在37μm处,含碳量达到最大值(峰值区),48~78μm为低含碳区。飞灰具有良好的分形特性,压汞仪测得的峰值区飞灰颗粒孔比体积、比表面积和孔隙率较大,而其分形维数较小(2.227),低含碳区飞灰分形维数为2.694。峰值区飞灰颗粒为致密的实心体,低含碳区飞灰颗粒为蜂窝状。基于SEM图像计算的分形维数与基于压汞实验所得的飞灰分形特性结论一致。     

粉煤灰混凝土的耐久性研究

研究了影响粉煤灰混凝土耐久性(抗渗性、抗冻性、抗碳化性、抗氯离子侵蚀性)的因素，通过理论分析指出掺粉煤灰改善了混凝土的耐久性，粉煤灰的三种基本效应即形态效应、活性效应、微集料效应是粉煤灰混凝土耐久性提高的重要因素。