粉煤灰气相法制备纳米白炭黑研究

研究了利用粉煤灰与氟化钙等反应,用气相法直接制备纳米级S iO2.xH2O的工艺条件。通过控制酸解和水解的速度,并在水解过程中加入乙醇作为分散剂,制备纳米白炭黑,借助红外光谱、XRD、TEM等技术对产物进行表征。结果表明,使用乙醇作为分散剂可以有效防止对纳米颗粒的团聚,制备出的白炭黑粒径可控制在10~20 nm,纯度高达99.95%。     

喷雾碳化法生产透明白炭黑新工艺研究

提出以ＣＯ２混合气体和水玻璃为原料，在几种助剂作用下，采用喷雾碳化、压榨式全自动厢式压滤、洗涤、旋转闪蒸干燥、滤液循环利用等新工艺、新设备生产活性（或透明）白炭黑产品。经过小试、扩大试验、模拟放大，建立２ｋｔ／ａ工业装置，其产品质量达到ＧＢ１０５１７－８９Ａ类指标。     

粉煤灰气相-水解法制备纳米白炭黑

以粉煤灰为主要原料，采用气相水解法制备纳米白炭黑，并对所得产品进行微观结构分析。先将粉煤灰按常规沉淀法制得白炭黑，再将白炭黑与氟化钙和浓硫酸混合加热生成四氟化硅气体，将该气体通入由氨水和分散剂组成的溶液中进行水解而制得纳米白炭黑。TEM和FTIR分析表明，采用分散剂SDS或CTAB制备的纳米白炭黑粒径较小，球形规整，未出现团聚现象，且具有较高的纯度。     

粉煤灰混凝土的碳化研究

粉煤灰掺量对混凝土碳化的影响是工程界普遍关心的问题。针对现有工程大量使用的低水胶比混凝土。研究了粉煤灰掺量对其碳化的影响。对不同粉煤灰掺量（0～60％）的低水胶比混凝土进行了室内快速碳化实验，建立了碳化经时模型。建立了单一粉煤灰影响因子模型，分析了粉煤灰掺量对混凝土空气渗透系数的影响。建立了粉煤灰影响因子、碳化时问双因素室内快速碳化寿命预测模型方程。结果表明，对低水胶比混凝土而言，粉煤灰掺量在0〈FA〈0．3之间，能提高其抗碳化能力；FA〉0.3，降低其抗碳化能力。     

粉煤灰短流程制取白炭黑的研究

采用浓碱熔出法短流程提取粉煤灰中的SiO2,结合相图分析、XRD和SEM等研究得出了最佳灰碱比,制备出纯度≥98%的白炭黑,通过对产品进行表面改性,获得纳米级白炭黑,通过测定表面羟基个数,验证了纳米SiO2的改性效果。     

掺粉煤灰的砂浆和同参数混凝土碳化相关性研究

随着混凝土的发展,矿物掺合料得到了广泛的运用,它们对混凝土抗碳化性能的影响成为国内外专家研究的热点。为了排除粗骨料对测定混凝土碳化边界的干扰,本论文以砂浆来代替同参数混凝土的角度着手,研究掺粉煤灰的砂浆的碳化行为及其和同参数混凝土的碳化行为的相关性,研究了不同水胶比,不同粉煤灰掺量,不同养护条件和不同龄期下的砂浆的碳化行为,同时研究了不同养护龄期和养护条件下同参数砂浆和混凝土碳化行为的相关性。研究结果表示粉煤灰掺量应控制在一定的范围,在28d龄期范围内,砂浆的碳化可以代替同参数的混凝土的碳化行为。     

粉煤灰混凝土的碳化-冻融特性研究

为了分析粉煤灰混凝土的碳化-冻融特性,制备了不同粉煤灰掺量的混凝土样品,利用室内试验方法对混凝土样品迚行冻融循环和碳化,分析混凝土样品的质量损失率、相对动弹性模量和碳化面积随粉煤灰掺量和冻融-碳化周期的变化觃律。研究结果表明:在冻融-碳化条件下,粉煤灰混凝土的质量损失率、弹模损失率以及碳化面积率均随粉煤灰掺量的增大出现了先增大后减小再增大的现象;对比分析结果表明,粉煤灰混凝土的碳化能够在一定程度上提高其抗冻能力;粉煤灰混凝土的碳化面积率随着冻融-碳化循环次数的增加而增大,且当冻融-碳化循环大于一定周期后,碳化面积趋于稳定。     

粉煤灰混凝土的抗碳化性能研究

阐述了混凝土的碳化机理,从其内部的物理、化学因素两方面分析了粉煤灰混凝土的抗碳化性能,提出了相应的改善措施.此外,还对粉煤灰混凝土碳化测试和评价方法进行了探讨,并提出从选择合适的养护条件和适当延长其养护时间来进一步完善粉煤灰混凝土碳化测试和评价方法.     

表面活性剂对碳化法制备白炭黑的影响研究

在碳化法制备白炭黑的过程中分别选用聚乙二醇6000、十二烷基苯磺酸钠、羧甲基纤维素等三种表面活性剂制备改性白炭黑。参察产品的性能，筛选合适的表面活性剂。     

酸浸法提取粉煤灰中氧化铝溶出规律的研究

酸浸法是粉煤灰提铝的主要方法之一。介绍了一种提取粉煤灰中氧化铝的方法,用不同浓度的硫酸作溶剂,用氟化钠作助溶剂,通过一定配比加入粉煤灰中反应。实验结果表明,当温度为沸腾温度、氟化钠添加量为0、硫酸浓度为12 mol/L、溶出时间为150 min时,氧化铝的溶出率可达80.19%。该工艺反应在低温常压下进行,避免了高温烧结工艺,节约了能源,降低了成本,具有较高的实用价值。     

用高硅废石与粉煤灰生产低碱水泥

我厂现有2条Φ4.0m×60m回转窑工艺线,1号为1500t/d窑外分解窑,2号为1000t/d立筒悬浮预热器窑,过去一直沿用石灰石、粘土、铁粉三组分配料,特别是粘土中碱含量(钠当量)高达3.15%～3.24%,严重制约着我厂低碱水泥的生产。通过选用碱含量低的废渣和低品位材料作水泥原料生产低碱水泥,不仅可以降低生产成本,节约原料,减少工业废渣对环境的污染,而且提高了产品质量。1低碱硅质原料的选取及配料方案的优化1.1低碱硅质原料的选择选择低碱硅质原料时遵循4个原则:①资源丰富并且质量相对稳定;②SiO2含量较高,一般要大于50%;③原材料价格便宜;④生产…     

复合碱激发剂协同处理高钙粉煤灰研制土聚水泥

采用复合碱激发剂协同处理高钙粉煤灰研制土聚水泥,试验确定了复合碱激发剂的模数和掺量、养护温度和养护时间,并研究了高钙粉煤灰基土聚水泥的抗压强度、反应产物和微观形貌。试验结果表明:复合碱激发剂适宜的模数为1.5,掺量为Na2O当量10%;适宜养护条件为75℃养护8h,然后在23℃室温养护至所需龄期,其28d抗压强度达63.4MPa;碱激发高钙粉煤灰过程中体系内同时生成土聚水泥凝胶和水化硅酸钙凝胶,并有类沸石矿物生成,反应产物与未反应的粉煤灰颗粒胶结成较为密实的高钙粉煤灰基土聚水泥硬化浆体。     

改性粉煤灰絮凝剂的制备及处理煤泥水的研究

通过亲水性单体的表面接枝聚合改善粉煤灰的表面亲水性,增加与水的接触,从而提高其净化污水效果。将粉煤灰分散在甲基丙烯酸溶液中聚合,制备聚甲基丙烯酸改性粉煤灰絮凝剂,然后对吸水率、红外、热重和SEM进行表征,并通过煤泥水的沉淀试验对絮凝能力进行研究。结果表明,该方法将甲基丙烯酸接枝聚合在粉煤灰表面制备FA-MA20絮凝剂,可以改善粉煤灰的亲水性,对煤泥水具有良好的絮凝能力。通过改善粉煤灰表面亲水性的方法可以提高对煤泥水的净化效果,对粉煤灰的综合利用及煤泥水处理具有重要的应用前景。     

Removal of boron from coal fly ash by washing with HCl solution

Boron as an environmentally regulated substance is well known to condense in the coal fly ash generated from coal combustion plants. Since boron in the coal fly ash tends to elute into the soil easily, a technology for its stabilization or removal from fly ash is required. An acid washing process is proposed and studied as one of the candidate technologies for the removal of boron from coal fly ash. A laboratory-scale investigation is conducted on the dissolution behavior of boron in the coal fly ash in a diluted HCl solution. The dissolution of boron and alkaline species is considerably fast and exhibits a behavior different from that of aluminum and silicon, which are major components of the ash. From the kinetic model, it is expected that boron in the ash may mainly be in the form of alkaline or alkaline earth borates that are deposited on the surface of relatively large ash particles of alumino-silicate or may be precipitated as fine particles during coal combustion. This acid washing process is extended to a bench-scale plant and boron is successfully removed from the coal fly ash until its content is less than the regulation limit.     

Removal of victoria blue from aqueous solution by fly ash

The use of fly ash for the removal of victoria blue (C126, 44045) from aqueous solution at different concentrations and pH has been investigated. The process follows first order adsorption rate expression and the rate constant was found to be 1.70 × 10^?2 min^?1 at a victoria blue concentration of 1.0 × 10^?4 M and 25°C. The uptake of victoria blue by fly ash is diffusion controlled and the value of mass transfer coefficient is 1.25 × 10^?5 cm sec^?1. The equilibrium data fit well in the Langmuir model of adsorption. Maximum removal was noted at pH 8.0. Low desorption of dye from adsorbent surface indicates that the process may not be essentially a reversible one.     

Adsorption of heavy metal ions from aqueous solution by fly ash

The removal characteristics of lead and copper ions from aqueous solution by fly ash were investigated under various conditions of contact time, pH and temperature. The influence of pH of the metal ion solutions on the uptake levels of the metal ions by fly ash were carried out between pH 4 and 12. The level of uptake of Pb²⁺ and Cu²⁺ ions by the fly ash generally increased, but not in a progressive manner, at higher pH values. The effect of temperature on the uptake of Pb²⁺ and Cu²⁺ ions was investigated between 30 °C and 60 °C, the adsorption of being enhanced at the lowest temperature. Rate constants were evaluated in terms of a first-order kinetics. The rate constant, k for uptake of Pb²⁺ and Cu²⁺ ions were 1.77 × 10⁻² s⁻¹ and 2.11 × 10⁻² s⁻¹, respectively. The experimental results underline the potential of coal fly ash for the recovery of metal ions from waste water. The main mechanisms involved in the removal of heavy metal ions from solution were adsorption at the surface of the fly ash and precipitation.     

粉煤灰酸法提取氧化铝的工艺研究进展

为了实现从高铝粉煤灰中提取氧化铝,进行了不同的氧化铝提取工艺的研究和比较。在对高铝粉煤灰性质进行分析的基础上,对碱法和酸法生产工艺的特点和适用性进行了比较,并阐述了采用酸法从循环流化床产生的粉煤灰中提取氧化铝的工艺路线。对硫酸浸取法、碱式硫酸法、酸碱联合法和一步酸溶法等4种酸法提取氧化铝的工艺路线和特点进行了综述,分析了不同工艺路线提取氧化铝的优势和缺陷。结果表明采用酸法从循环流化床粉煤灰提取氧化铝是可行的,有望实现工业化的工艺。     

Preparation and characterization of fully waste-based glass-ceramics from incineration fly ash,waste glass and coal fly ash

Municipal solid waste incineration (MSWI) fly ash (FA) is a typical hazardous waste due to its high contents of toxic heavy metals, and hence its disposal has attracted global concern. In this work, it was recycled into environmental-friendly CaO–Al₂O₃–SiO₂ system glass-ceramics via adding coal fly ash (CFA) and waste glass (WG). The effects of CaO/SiO₂ ratios and sintering temperatures on the crystalline phases, morphologies, mechanical and chemical properties, heavy metals leaching and potential ecological risks of glass-ceramics were investigated. The results showed that wollastonite (CaSiO₃), anorthite (CaAl₂Si₂O₈) and gehlenite (Ca₂Al₂SiO₇) were the dominant crystals in the glass-ceramics, which were not affected by CaO/SiO₂ ratio and sintering temperature. The compressive strength increased, while the Vickers hardness and microhardness decreased as increasing the sintering temperatures from 850 to 1050 °C, which reached their maximum values of 660.69 MPa, 6.14 GPa, and 7.43 GPa, respectively. However, the increase of CaO/SiO₂ ratio resulted into the reduction of the three mechanical parameters. As varying CaO/SiO₂ ratio from 0.48 to 0.86, the maximum compressive strength, Vickers hardness and microhardness were 611.80 MPa, 5.43 GPa, and 6.56 GPa, respectively. Besides, all the glass-ceramics exhibited high alkali resistance of >97%. The extremely low heavy metals leaching concentrations and low potential ecological risk of glass-ceramics further revealed its environmentally friendly property and potential application feasibility.     

Effect of yttria on sintering and microstructural behavior of reaction sintered mullite based on bauxite,fly ash and precipitated silica

The present investigation on the effect of Y₂O₃ towards the sintering behavior of mullite compacts revealed that rapid mullitization occurred through nucleation and normal grain growth due to the formation of yttrious silicate glassy phase. The intergranular voids were progressively eliminated by yttrious silicate glass leading to significant decrease in porosity with the corresponding remarkable rise in mechanical strength of sintered compacts. The uniform dispersion of microfine corundum grains into the mullite matrix with 1.5% Y₂O₃ content was noticed during sintering at 1550?°C and above.