以粉煤灰和赤泥为原料烧结陶瓷工艺与性能研究

本文研究了在1050 ℃至1200 ℃之间温度对以粉煤灰赤泥为原料烧结陶瓷的物相和烧结性能的影响.结果表明:实验用粉煤灰原料的主要矿相组成为石英(SiO_2)和莫来石(3Al_2O_3·2SiO_2),赤泥原料的主要矿相组成有钙铝黄长石(Ca_2Al_2SiO_7)、石英(SiO_2)、钙铁榴石(Ca_3Fe_2+3(SiO_4)_3)和钙钛榴石(Ca_3TiFeSi_3O_(12));以粉煤灰赤泥为原料的5组不同配比试样在1200 ℃时试样气孔率相对降低,体积密度和抗压强度相对程度增大;其中5#试样在经1200 ℃烧结后的气孔率为1.67%,体积密度为2.10 g·cm~(-3),抗压强度为123.23 MPa,达到较好的烧结致密状态,试样主要物相是钙钠长石和莫来石.试样内莫来石的形成及玻璃液相的增加促进烧结并在1200 ℃达到致密烧结状态.     

Mechanical and leaching properties of neodymium-contaminated soil glass-ceramics

The safe treatment of radioactive-contaminated soil is of great significance. In this work, neodymium-contaminated soil was successfully immobilized using microwave sintering to form glass-ceramics. The microstructure, morphology, elemental distribution, Vickers hardness, and chemical durability of the sintered samples were analyzed. The results showed that the glass-ceramic is more suitable to immobilize the waste compared with the glass matrix. XRD and SEM-EDS results proved that the waste form has been totally immobilized in the sintered matrix whether in glass-ceramics and glass. However, the leaching rate of element Nd in glass-ceramic was lower than the glass matrix at 28 d. Moreover, the Vickers hardness results of glass-ceramic were higher than that of glass. Thus, glass-ceramics can not only reduce sintering temperature and save energy but also achieve a better immobilizing effect. Our investigation reflects that glass-ceramics are more suitable for neodymium-contaminated soil immobilization using the microwave sintering method.     

Technological properties of glass-ceramic tiles obtained using rice husk ash as silica precursor

This paper reports the results of a study focused on the obtainment of glass-ceramic by using rice husk ash (RHA) as silica precursor. RHA is a by-product generated in biomass plants using rice husk as fuel for kilns or in the rice mills to generate steam for the parboiling process. Worldwide, it is annually produced about 132 Mt of rice husk, which gives rise to a production of 33 Mt/year of RHA. Glass-ceramic tiles were produced by a sinter-crystallization process using a glassy frit formulated in the MgO–Al₂O₃-SiO₂ composition system. The realized glass-ceramics were studied according to ISO rules for sintering and technological properties (water absorption, apparent density, bending strength, Young's modulus, deep abrasion, Mohs hardness). To complete the investigation crystalline phase formation and microstructural characterization of the glass-ceramic materials was carried out using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Finally, chemical durability tests on parent glass and derived glass-ceramics were performed. The results obtained showed that it is possible to use RHA to produce glass-ceramic tiles by a sinter-crystallization process, obtaining nepheline (Na₂O*Al₂O₃*SiO₂) as main crystalline phase and forsterite (2MgO*SiO₂) at 900 °C. Regarding technological features, the sintered materials showed bending strength values and Mohs hardness higher with respect to commercial glass-ceramics like NeopariesR. Other properties as water absorption (0.5%) allowed to classify these materials into the Group BIa characteristic of high sintered ceramic tiles according to European Standard rule.     

矿物掺合料改性磷酸镁水泥研究进展

在总结磷酸镁水泥水化产物、水化速度、孔结构、流动性和物理力学性能等的基础上,综述了粉煤灰、矿渣、硅灰、赤泥和偏高岭土等矿物掺合料对磷酸镁水泥的改性效果和作用机理。矿物掺合料改性磷酸镁水泥具有优异的物理力学性能和经济性,耐水性、严苛条件下耐久性、负温下水化硬化特征和矿物掺合料改性机制等课题尚待深入研究,以期为促进磷酸镁水泥及其修补砂浆在重点工程中的应用提供参考。     

硅灰掺量对免烧粉煤灰陶粒性能的影响

以粉煤灰为原料,辅掺硅灰制备了碱激发免烧陶粒。采用筒压强度试验、吸水率试验、含泥量试验、磨破率试验、耐腐蚀试验、X射线衍射仪和扫描电子显微镜试验,系统地研究了硅灰掺量对陶粒性能的影响。结果表明,3 d、7 d、14 d龄期时,随着硅灰掺量增加,粉煤灰陶粒的筒压强度呈逐渐增加趋势,磨破率与吸水率呈逐渐下降趋势,耐腐蚀性能也得到提高。当硅灰掺量为15%和20%(质量分数)时,龄期为14 d时,陶粒的筒压强度分别达到19.43 MPa和20.37 MPa。由微观分析知,适量的硅灰掺量可以提高粉煤灰的水化程度,增加陶粒结构密实性,但当掺量达到15%~20%时,水化程度有所减弱。     

严苛侵蚀作用对优化导电混凝土性能的影响

干湿交替和硫酸盐腐蚀引起的损伤严重影响导电混凝土服役时的长期稳定性。本研究以碳纤维、石墨作为导电相材料,掺入粉煤灰和硅灰制备导电混凝土,在干湿交替和硫酸盐腐蚀耦合作用下,讨论粉煤灰、硅灰掺量对导电混凝土力学性能与电学性能的影响。综合导电混凝土的力学性能与电学性能衰变定义了服役性能劣化指标。结果表明：掺入粉煤灰和硅灰后提升了导电混凝土在干湿交替和硫酸盐腐蚀下的耐久性和导电稳定性;当粉煤灰和硅灰的总掺量一定时,提高粉煤灰占比能够有效降低干湿交替和硫酸盐腐蚀造成的强度损失,并提高导电混凝土的导电稳定性。     

Production of ceramics from coal furnace bottom ash

Furnace bottom ash (FBA) is generated in significant quantities from coal fired power stations and is a problem when commercially viable reuse applications do not exist locally. Representative samples of FBA from the Kilroot power station in Northern Ireland have been milled, pressed and sintered at a range of temperatures to form new ceramic materials. The effect of adding recycled glass to the mix has been investigated. The optimum FBA ceramics were produced by sintering at 960 °C and these had a density of 2.388 g/cm³, zero water adsorption indicating minimal open porosity, and a Vickers hardness comparable to commercially available glass-ceramics. The addition of 20% by weight of glass reduced shrinkage during sintering, while the samples maintained high density and hardness. This glass addition allows greater dimensional control during sintering to form FBA ceramic tiles. The research demonstrates that FBA can be processed into ceramics for use in higher value products compared to conventional use as lightweight aggregate. Further research is required to optimize processing and fully characterize material properties. This novel approach to managing FBA has potential to transform a problematic waste in Northern Ireland into a valuable resource.     

Double-layer waste-derived glass-ceramics prepared by low temperature sintering/sinter-crystallisation

Lightweight glass-ceramics with a dense surface layer were produced by a novel sintering approach. The surface porosity of a glass-ceramic body from the direct sintering of an engineered mixture of fly ash from thermal power plants, recycled soda-lime glass and boron waste (residues of the mining and purification of valuable boron containing minerals) was sealed by a glaze, deriving from the sinter-crystallisation of glass powders produced from the same mixture. The use of boron waste, providing B₂O₃, allowed a substantial viscous flow, for the substrate, even at the relatively low temperature (850–950°C) adopted for a single firing treatment (simultaneous sintering of substrate and sinter-crystallisation of glaze). The dense sinter-crystallised layer, besides imparting improvements in the mechanical properties, was found to feature an enhanced chemical stability.     

Novel glass ceramic foams materials based on red mud

Glass ceramic foams were prepared using red mud and fly ash with added CaCO₃ as foaming agents. The aim of the present work was to investigate the possibility of adding red mud, an alkaline leaching waste, in the raw material for the preparation of glass ceramic foams. The results of mineralogical analyses as well as the microscopic examination showed that the use of the red mud affect the mineralogical characteristics and structures of the as produced foams. The influence of amount of red mud on the bulk density and compressive strength of samples was further evaluated. The experimental results showed that relatively low bulk density foams (0.33–0.41 g/cm³) could be obtained by using low sintering temperature (760–840 °C) when the red mud/fly ash ratio does not exceed 40:60. The reduction of sintering temperature or, above all, the reduction of the holding time, was found to limit the coalescence and significantly improve the compressive strength of the foams (0.33–2.74 MPa).     

利用提钒尾渣制备烧结广场砖实验研究

以提钒尾渣为主要原料,采用半干法成型方法制备烧结广场砖,通过添加广西白泥、硅铁灰、粉煤灰和A12O3粉可以优化提钒尾渣烧结广场砖的物理指标,提高烧结广场砖的性能.通过条件试验较系统研究了广西白泥配入量、粉煤灰、硅铁灰和A12O3粉配入量对烧结广场砖常温耐压强度和吸水率的影响.条件试验表明:广西白泥配入量为20%左右较适宜、硅铁灰配入量控制在5%以内较适宜、粉煤灰配入量控制在6%以内较适宜、Al2O3粉添加量控制在8%以内较适宜.制得提钒尾渣广场砖的常温耐压强度达到28 MPa以上,吸水率可以降低到10%左右.     

粉煤灰/硅灰复合掺合料对水泥净浆性能的影响

研究了水泥标准稠度用水量、粉煤灰掺量、硅灰掺量、粉煤灰与硅灰双掺对水泥净浆性能的影响.结果表明,硅灰使水泥净浆需水量明显增加,粉煤灰、硅灰双掺可克服单掺粉煤灰早期强度低的缺点,短期内能提高水泥净浆的抗压强度.     

矿物掺合料对机制砂砂浆性能的影响

研究了在相同水灰比与流动度情况下,单掺或复掺硅灰及不同地区粉煤灰等矿物掺合料对机制砂砂浆流动性、强度的影响,并与标准砂砂浆进行了比较。结果表明、与标准砂相比,机制砂砂浆需水量大、保水性差、易泌水,但具有增强作用;硅灰引起机制砂砂浆流动性减小、减少泌水、增进强度。水灰比相同时,随掺量灰增大,机制砂砂浆流动性增大,不同龄期下砂浆抗压强度均下降。复掺硅灰与粉煤灰可提高机制砂的强度。上海与贵州两地的粉煤灰品质基本相同,对砂浆性能的影响也基本相同。     

Use of recycled copper slag for blended cements

Copper slag is a by‐product generated during smelting to extract copper metal from the ore. The copper slag obtained may exhibit pozzolanic activity and may therefore be used in the manufacture of addition‐containing cements. In this paper the effect of the incorporation of the copper slag in cement is measured. Blends of copper slag with Portland cement generally possess properties equivalent to Portland cement containing fly ash, but very different to the silica fume incorporation. Copper slag and fly ash reduce the heat of hydration more effectively than silica fume in mortars. The replacement of 30% cement by copper slag reduces the flexural and compressive strength in a similar way to fly ash; however, after 28 days, the reduction is less than the percentage of substitution. Hydrated calcium aluminate phases were analysed using scanning electron microscopy (SEM) and X‐ray diffraction (XRD) techniques. The pozzolanic activity of copper slag is similar to that of fly ash and higher than silica fume. In the presence of low water/cement ratios, certain pozzolanic materials produce a very compact cement paste that limits the space available for hydration products, a determining factor in the formation of hydrated calcium aluminates. SEM was found to be a useful analytical technique when aluminates are formed and can be clearly detected by XRD. Copyright © 2008 Society of Chemical Industry     

Photocatalytic properties of ZnO nanoparticle coating on porous ceramic substrates with varying porosities produced from fly ash and red mud

In order to improve filtering efficacy, nanoparticles are often deposited as photocatalytic degrading agents onto porous ceramics. This study aimed to deposit ZnO nanoparticles on ceramic substrates produced from fly ash and red mud with adjustable porosity and investigate their photocatalytic properties. To achieve this goal, at first porous ceramics were produced and sintered at various temperature/time intervals. It was observed that sintering at 800°C for 120 min provided a proper structure and porosity. In addition, MgO replacement with MgCO₃ lowered the water absorption of the samples from 25.63% to 11.45%. The samples were then coated with ZnO nanoparticles using the sol–gel method and the ZnO structures obtained were micron-sized plates. It was observed that increasing porosity increased the ZnO amount and accordingly the photocatalytic properties of the products. During the adsorption tests conducted in the dark, the coated ceramic samples were stained with MB with a maximum MB adsorption ratio of ∼14%. On the other hand, no visible MB stain was observed on the samples that were exposed to UV irradiation, and the MB removal after the UV irradiation was 93.6%; therefore, it was concluded that the dominant MB removal mechanism was photocatalytic.     

用工业废渣赤泥研制微晶玻璃

本研究利用山东铝业公司固体废弃物赤泥、粉煤灰、煤矸石等为主要原料,制备了装饰材料用微晶玻璃。探讨了微晶玻璃的热处理工艺制度及晶核剂对核化、晶化的影响。采用TG-DTA、XRD、SEM等测试技术测试了样品的理化性能和微观结构。     

热压烧结制备粉煤灰建筑陶瓷的工艺研究

以固体废弃物粉煤灰为主要原料,通过对原料进行预烧处理工艺得到活化粉煤灰粉体,分别在850 ℃、875℃、900 ℃、925 ℃、950 ℃度进行真空热压烧结,制备粉煤灰建筑陶瓷复合材料.利用XRD对复合材料的物相组成进行分析、采用SEM分析样品的微观结构,结合烧成样品的吸水率、体积密度、硬度等,分析不同的烧结温度对陶瓷性能的影响.结果表明:真空热压烧结过程中,随着温度升高,样品低共熔相增多,致密化程度增加.当烧结温度达到925℃时,所得复合陶瓷材料晶粒分布均匀、细小,晶粒尺寸为0.4~0.5 μm;陶瓷样品的体积密度、吸水率、硬度分别为2.62 g/cm3、0.05%、6.5 GPa.     

活性掺合料对环氧树脂修补砂浆综合性能的影响

为了探究活性掺合料对环氧树脂修补砂浆的改性效果,为修补工程应用提供依据。研究硅灰和粉煤灰对环氧树脂修补砂浆力学性能、粘结强度、尺寸稳定性和抗冻性的影响,并采用扫描电子显微镜(SEM)和压汞法探究和分析影响机理。结果表明:环氧树脂使砂浆抗压强度降低,掺入硅灰可补偿强度损失,掺粉煤灰砂浆的强度随龄期增加而增加,但其中28 d和56 d强度低于对照组;硅灰和低掺量(≤10%,质量分数)粉煤灰可以提高修补砂浆粘结强度;硅灰对修补砂浆尺寸稳定性有不利影响,粉煤灰则相反;砂浆的抗冻性随着硅灰掺量增加先增加后降低,随着粉煤灰掺量增加而降低。     

铝镁质量比对矿渣微晶玻璃的影响研究

以白云鄂博二次选后尾矿和粉煤灰为主要原料,采用熔融法制备得到了CaO-MgO-Al2O3-SiO2系矿渣微晶玻璃。利用DTA、XRD、SEM等研究了Al2O3/MgO质量比对微晶玻璃结构及力学性能的影响。结果表明:Al2O3/MgO比值的增加有助于晶化温度的升高。Al2O3/MgO质量比为3.3时,得到的微晶玻璃密度最大,综合力学性能最优。     

硅灰、偏高岭土对矿渣-粉煤灰微珠胶凝材料性能的影响

首先通过改变粉煤灰微珠掺量,确定满足快速修补要求的矿渣-粉煤灰微珠胶凝材料基体的最佳配比,再调节偏高岭土、硅灰掺量,研究其对复合胶凝材料凝结时间、力学性能和水化机理的影响。研究发现,偏高岭土对凝结时间的改变较硅灰更敏感。通过化学结合水测试,分析了不同硅灰和偏高岭土掺量对矿渣-粉煤灰微珠胶凝材料水化反应程度影响的原因。力学实验结果表明：矿渣-粉煤灰微珠胶凝基体复合掺加5%硅灰（质量分数）+15%偏高岭土（质量分数）,试块2 h抗压强度为11.5 MPa、28 d抗压强度达到75.2 MPa,且呈现缓慢递增的趋势。     

矿物超细粉对水泥浆体化学收缩的影响研究

通过笔者自行设计的化学收缩测量装置分别对掺硅灰、磨细矿渣、超细粉煤灰的水泥浆体化学收缩进行了测定。结果表明，硅灰的掺入增大了水泥浆的化学收缩；磨细矿渣的掺入使水泥浆体的化学收缩稍有增长，但不十分明显；而超细粉煤灰则可以较好地抑制水泥浆体的化学收缩。对掺矿物掺合料的水泥浆体强度的测试结果从另一个角度论证了化学收缩是由水化引起的，即水化程度的大小反映了化学收缩的大小。