石灰-石膏-粉煤灰水泥浆体的水化机理研究

通过增钙法对粉煤灰水泥浆体的凝结时间、水化放热和力学性能的测定,以及采用差示热重分析、扫描电镜、X射线衍射,研究了在有石灰、石膏时不同掺量粉煤灰水泥浆体的水化机理。结果表明：早期水化性能弱,后期持久。随粉煤灰掺量增加,浆体的凝结时间延长,水化热减少,高掺超过40%时龄期强度下降明显;早期水化产物主要为：大量的水化硅酸钙凝胶(C-S-H）,未水化的硅酸钙（C₃S、 C₂S）,少量的钙矾石（AFt、 AFm）和氢氧化钙Ca(OH)₂,后期在石灰石膏的活性效应和填充效应的激发下,水化产物主要为：Ca(OH)₂、AFm。Ca(OH)₂与AFm及少量的C-S-H填充在水泥孔隙中且相互交联,改善了粉煤灰水泥浆体强度。     

赤泥掺加硅灰用于道路基层材料的试验研究

选用洛阳某铝业尾矿库赤泥为试验材料,添加不同量的水泥、粉煤灰和硅灰,采用单因素正交试验,分析赤泥固化体的无侧限抗压强度、微观形貌及其浸出液的pH、含氟量,得出赤泥道路基层材料的最佳配合比:水泥掺量10%(质量分数,下同),粉煤灰掺量10%,硅灰掺量15%。该配合比在工程上不仅能满足道路基层技术要求,通过掺加硅灰还减小了水泥掺量,使赤泥固化体浸出液的碱性和含氟量降低。     

烧结法赤泥的强度演化规律

筑坝堆存是现在处理赤泥的主要方式,为了堆场安全继续向上堆载,对烧结法赤泥强度的演变规律进行了研究。通过对比不同深度处赤泥的抗剪强度,表明赤泥强度的形成与堆载时间没有必然的联系;再通过对新进场的赤泥进行强度追踪,得到赤泥强度形成过程中抗剪强度与滤水固结时间的关系曲线,从时间因素上为赤泥的安全堆载提供一个理论依据。     

CFBC固硫灰和粉煤灰复掺作水泥混合材的研究

循环流化床燃烧技术是一种节能环保的先进燃烧煤技术,但其燃烧产物固硫灰的综合利用是个重要难题.将CFBC固硫灰和普通粉煤灰复合化处理,研究了复合混合材对水泥胶砂物理性能和水泥净浆膨胀性能的影响.实验结果表明:固硫灰和粉煤灰复掺存在超叠加效应,在合适的互掺比例和细度下复合混合材具有比单掺更好的水泥胶砂强度;掺加30%复合混...     

不同含水率条件下拜耳法赤泥强度及水力学特性

在利用XRD、XRF、SEM等微观测试手段分析了拜耳法赤泥的化学成分、矿物组成和微观结构的基础上,通过无侧限抗压强度实验、固结排水三轴剪切实验研究了拜耳法赤泥在不同水力路径条件下其强度特性的变化规律;同时通过非饱和土瞬态水力特性循环实验系统对拜耳法赤泥的水力学特性进行了研究。研究表明:含水率的变化对拜耳法赤泥的强度特性有较大程度的影响,在脱水干燥过程中,其抗压强度和抗剪强度指标均有较大程度的增长;拜耳法赤泥具有遇水崩解现象,已干燥硬化的赤泥会遇水崩解,强度指标明显降低,且在较低应变处即发生脆性破坏;拜耳法赤泥的土-水特征曲线和渗透系数特征曲线均展现出明显的滞后效应,说明拜耳法赤泥对水有较大的敏感性,在降雨条件影响下,拜耳法赤泥堆体的稳定性有一定程度的降低。     

赤泥的土壤化改良研究进展综述

赤泥是氧化铝生产过程中产生的固体废弃物，年产量和堆存量大，理化性质极端，严重威胁赤泥堆场周边生态环境和居民健康。赤泥土壤化改良和堆场生态修复被认为是最有希望解决赤泥问题的方法之一。对赤泥的基本理化性质，赤泥土壤化改良机理、改良措施(基质改良、植物修复和微生物修复等)及其存在问题、改良过程中的潜在生态环境风险等进行了研究和总结分析，并对赤泥土壤化改良领域未来的研究工作进行了展望和建议。     

改性拜耳法赤泥颗粒的制备及对土壤铅的稳定化处理

拜耳法赤泥产量大且成分复杂,碱性强,难处理,易引起环境污染。而近年土壤重金属污染形势严峻,儿童血铅中毒事件时有发生。针对上述问题,以拜耳法赤泥为主要原料,加入少量水泥等添加剂改性制备赤泥基颗粒材料,并将其应用于土壤中铅的稳定化。结果表明,材料配方为2%水泥+5%石膏+5%粉煤灰+5%磷酸二氢钙+83%,水灰比为0.5,圆盘造粒参数为28°α40°、20r·min~(-1)R40r·min~(-1)时为颗粒最佳条件。按此配方制备的赤泥颗粒对铅污染浓度为100、250、500和800mg·kg~(-1)的模拟污染土壤进行修复,当投加5%的颗粒,稳定10d后,土壤中铅的生物可利用态分别降低了72.52%、65.38%、64.73%和40.03%,而残渣态增加了43.4%、35.13%、43.42%和43.97%,有随着污土浓度增加而增加的趋势,表明赤泥制备成颗粒材料后能有效稳定土壤中不同浓度的铅。     

利用多年期赤泥和煤矸石制备烧结砖

以多年期赤泥和煤矸石为主要原料,分析了其化学成分和物性特征,通过设计不同的原料配比和烧结温度,探讨其最佳工艺条件以及各种参数指标,试图为赤泥的大宗化利用提供一种新的途径。实验结果表明最佳工艺条件为:多年期赤泥与煤矸石质量比为20∶80,成型压力为6 MPa,烧结温度为1 100℃左右保温2 h。烧结砖体"泛霜"现象基本消失,抗压强度为12.18 MPa、吸水率为21.6%,满足国家粉煤灰普通烧结砖GB5101-2003中的要求。     

湿法脱硫中石灰石溶解特性的模型及实验研究

在石灰石-石膏湿法烟气脱硫中,石灰石的溶解影响到浆液吸收SO2的能力及吸收塔持浆池的大小.根据传质及化学离子平衡理论,建立了石灰石的溶解模型,并通过实验对模型进行了验证,结果表明,模拟结果与实验值基本一致,模型较好地反映出石灰石的溶解过程;在浆液pH较低的情况下,通过增强搅拌强度,可以明显提高石灰石的溶解速率,而在浆液...     

城市污水污泥固结体重金属浸出毒性及路用性能研究

城市污水污泥的重金属离子Pb、Zn超过国家固体废弃物排放最高允许值,属于危险废物。污水污泥的最佳出路是无害化处理,资源化利用,产业化发展。研究了以上海市污水污泥为原料,加入一定比例的固化剂和矿物掺合料使之固结,经养护满足路用强度性能,测试其固结体重金属离子浸出质量浓度亦满足国家固体废弃物排放标准,即污泥中的重金属离子得到有效的束缚和稳定固化,既解决了环境问题,又为污泥产业化发展开辟了新的途径。     

Latent hydraulic reactivity of blended cement incorporating slag made from municipal solid waste incinerator fly ash

The reactivity of cement pastes made by blending Portland cement with slag from municipal solid waste incinerator (MSWI) fly ash was investigated to assess the potential of recycling MSWI fly ash slag. The slag, prepared by melting MSWI fly ash at 1400 degrees C for 30 min, was pulverized and ground, then blended with ordinary Portland cement (OPC), using various substitution levels to make slag-blended cement (SBC). The pozzolanic reactivity of the ecocement was then characterized by determining variations in the compressive strength, degree of hydration, microstructure, speciation, and mineralogical crystalline phases. The results suggest that the strength of the pastes at an early age decreased with increasing substitution levels, whereas the strength at a later age of the tested pastes (with substitution levels less than 10%) outperformed OPC paste because of typical SBC properties. The development of strength at a later age was also confirmed by X-ray diffraction and scanning electron microscopy techniques. This implies that active silica (Si) and alumina (Al) react with the hydration product, calcium hydroxide (Ca(OH)2), to form calcium silicate hydrate (C-S-H), which contributed to strength development at a later age by the filling up of pores in the SBC pastes. The pozzolanic activity of the SBC pastes indicates that it is suitable for use as a substitute for OPC in blended cement.     

Latent Hydraulic Reactivity of Blended Cement Incorporating Slag Made from Municipal Solid Waste Incinerator Fly Ash

Abstract

The reactivity of cement pastes made by blending Portland cement with slag from municipal solid waste incinerator (MSWI) fly ash was investigated to assess the potential of recycling MSWI fly ash slag. The slag, prepared by melting MSWI fly ash at 1400 °C for 30 min, was pulverized and ground, then blended with ordinary Portland cement (OPC), using various substitution levels to make slag-blended cement (SBC). The pozzolanic reactivity of the ecocement was then characterized by determining variations in the compressive strength, degree of hydration, microstructure, speciation, and mineralogical crystalline phases. The results suggest that the strength of the pastes at an early age decreased with increasing substitution levels, whereas the strength at a later age of the tested pastes (with substitution levels less than 10%) outperformed OPC paste because of typical SBC properties. The development of strength at a later age was also confirmed by X-ray diffraction and scanning electron microscopy techniques. This implies that active silica (Si) and alumina (Al) react with the hydration product, calcium hydroxide (Ca(OH)₂), to form calcium silicate hydrate (C-S-H), which contributed to strength development at a later age by the filling up of pores in the SBC pastes. The pozzolanic activity of the SBC pastes indicates that it is suitable for use as a substitute for OPC in blended cement.     

Aerosol laser ablation mass spectrometry of suspended powders from PM sources and its implications to receptor modeling

Primary sources of particulate matter (PM) were analyzed by suspending powdered samples into an aerosol laser ablation mass spectrometer (LAMS). PM sources studied included vehicle exhaust particulates, dust from a non-ferrous smelter, cement powder, incinerator fly ash, two coal fly ash samples, and two soils. Marker peaks signified certain PM source sectors: construction particles could be distinguished by abundant Ca and Ca compounds, fuel combustion was marked by elemental carbon clusters, and nonferrous industrial particles showed inorganic As, Cu, Pb, Zn, and SOx. In addition to the distinction between particles from these different source sectors, mass spectral results also showed that for a single source, different particle types existed, and among different sources within a sector, similar spectra were present. The aerosol LAMS results show the difficulty in differentiating among separate fly ash sources as well as among different soil samples. A particle class balance receptor model that measures the amount of specific particle types rather than the amount of a chemical component is suggested as a means of source apportionment when particle spectra with overlapping source possibilities occur. The assumptions and limitations of receptor modeling aerosol LAMS data are also described. In particular, methods need to be developed to account for the contribution of secondary sources.     

流化床锅炉飞灰活性激发与建材利用的试验研究

流化床锅炉飞灰活性较差,常规的粉煤灰活性激发方法对该飞灰效果不佳.本研究采用了加入适当激发剂的方法激发其活性,结果表明,加入激发剂后水泥胶砂的早期抗折、抗压强度均有100%的增长,后期抗折强度提高约100%、抗压强度提高60%以上,凝结时间和安定性均符合要求.水泥中飞灰掺量达40%时,其胶砂各龄期强度均达到甚至超过了42.5R水泥的强度;飞灰掺量65%～75%时,胶砂强度显示仍可生产一些低强度要求的建材产品,如砌筑水泥、建筑砂浆等.采用XRD、SEM等微观测试手段对飞灰活性激发机理进行了探讨.     

Pozzolanic reactivity of the synthetic slag from municipal solid waste incinerator cyclone ash and scrubber ash

This study investigates the pozzolanic reactions and compressive strength of the blended cement manufactured using synthetic slag obtained from municipal solid waste incinerator (MSWI) cyclone ash and scrubber ash as partial replacement of portland cement. The synthetic slag was made by co-melting the MSWI scrubber ash and cyclone ash mixtures at 1400 degrees C for 30 min. Following pulverization, the different types of slag were blended with cement as cement replacement at ratios ranging from 10 to 40 wt %. The synthetic slag thus obtained was quantified, and the characteristics of the slag-blended cement pastes were examined. These characteristics included the pozzolanic activity, compressive strength, hydration activity, crystal phases, species, and microstructure at various ages. The 90-day compressive strength developed by slag-blended cement pastes with 10 and 20 wt % of the cement replaced by the synthetic slag outperformed ordinary portland cement by 1-7 MPa. X-ray diffraction species analyses indicated that the hydrates in the slag-blended cement pastes were mainly portlandite, the calcium silicate hydrate gels, and calcium aluminate hydrate salts, similar to those found in ordinary portland cement paste. Differential thermal and thermogravimetric analysis also indicated that the slag reacted with portlandite to form calcium silicate hydrate gels.     

Hydration properties of eco-cement pastes from waste sludge ash clinkers

Three types of hydraulic cements have been developed by incorporating sludge ash from a primary sewage treatment plant and a water purification plant, as well as slag from steelworks (ferrate), as a partial replacement for clay, silica, alumina, and iron oxide in raw cement meal. The raw meal for the pre-determined recipes was prepared by heating it to 1400 degrees C for 6 hr in a clinkerization process, using a simulated incinerator and smelter. The major components of ordinary Portland cement, C3S, C2S, C3A, and C4AF, were all found in the clinkers. Of the three types of eco-cements, the eco-cement A paste was most similar to ordinary Portland cement in terms of composition and compressive strength development, while the eco-cement B paste showed early strength development. The differential thermal analysis species analyses indicated that the hydrates in the eco-cement pastes were mainly calcium hydroxide and CSH gels, like those found in ordinary Portland cement paste. Moreover, the degree of hydration, as determined by nuclear magnetic resonance, increased in all eco-cement pastes with an increasing curing age. The results indicate that it indeed is feasible to use sludge ash and ferrate to replace up to 20% of the mineral components of raw materials for cement.     

高铝粉煤灰提取氧化铝后硅钙渣用作水泥混合材

为了使高铝粉煤灰提取氧化铝后所产生的硅钙渣被大量的用作水泥混合材,通过水泥强度、水化放热和干缩性实验研究了原状硅钙渣和脱碱硅钙渣对水泥强度和稳定性的影响。结果表明,当硅钙渣掺量达30%时,硅钙渣水泥强度仍可满足P·C 32.5水泥要求。且随硅钙渣掺入量的增加,水泥早期水化放热速率增加的同时水泥累计水化放热量和干缩率还会显著降低。与原状硅钙渣相比,在同等掺量的情况下,脱碱硅钙渣更有利于保持水泥强度,降低其水化热和改善干缩性。     

基于响应面法的污泥快速固化效能综合影响

针对现有污泥固化技术存在的固化养护时间长、低温条件下固化效能低等问题。研究提出污泥快速（3d）固化技术,采用响应曲面分析方法,重点考察了石灰、组分A、硅酸盐水泥、粉煤灰和温度等5因素对固化效能的综合影响,研究结果表明,石灰、组分A、硅酸盐水泥、粉煤灰和养护温度等因素对3d固化体的无侧限抗压强度和含水率的线性效应显著,石灰和组分A、石灰和养护温度对无侧限抗压强度的交互影响显著,石灰和粉煤灰、组分A和养护温度、硅酸盐水泥和粉煤灰对含水率的交互影响显著;得出了5因素对固化体3d无侧限抗压强度和含水率影响的定量模型,可对污泥快速固化进行优化和预测;并利用XRD和SED对污泥固化块的化学成分和微观结构进行了分析。     

基于响应面法的污泥快速固化效能综合影响简

针对现有污泥固化技术存在的固化养护时间长、低温条件下固化效能低等问题。研究提出污泥快速（3 d）固化技术,采用响应曲面分析方法,重点考察了石灰、组分A、硅酸盐水泥、粉煤灰和温度等5因素对固化效能的综合影响,研究结果表明,石灰、组分A、硅酸盐水泥、粉煤灰和养护温度等因素对3 d固化体的无侧限抗压强度和含水率的线性效应显著,石灰和组分A、石灰和养护温度对无侧限抗压强度的交互影响显著,石灰和粉煤灰、组分A和养护温度、硅酸盐水泥和粉煤灰对含水率的交互影响显著;得出了5因素对固化体3 d无侧限抗压强度和含水率影响的定量模型,可对污泥快速固化进行优化和预测;并利用XRD和SED对污泥固化块的化学成分和微观结构进行了分析。     

粉煤灰利用研究进展

本文对粉煤灰综合利用的研究现状进行综述。内容包括粉煤灰用于烧结砖、蒸养砖、墙体材料和水泥生产、隔热防水材料、絮凝剂和肥料制备、土壤改良和废水处理等。此外,还对从粉煤灰中回收金属矿物和炭粒等进行了讨论。