利用活化粉煤灰制备高掺量粉煤灰烧结砖

研究了分别经机械和化学活化后的粉煤灰对高掺量粉煤灰烧结砖性能和显微结构的影响。结果表明:用磨细粉煤灰代替原灰配料,可以改善烧结砖的力学性能,尤其是砖的抗压强度能显著提高。当用掺量质量分数为60%的磨细灰制砖时,烧结砖的抗压强度提高至原灰烧结砖的2倍,并且有更为致密的微结构。在粉煤灰砖中加入质量分数为2%的外加剂D进行化学活化后,可明显改善干坯强度,并提高烧结砖的抗压强度。     

Use of mineral coal ashes in insulating refractory brick

Coal ash from Candiota thermoelectric power plant in southern Brazil is a waste generated in great amount. Current estimates indicate that coal ash production is likely to reach 2.000.000 tons per year. Of this total, only 10% are commercialized, so the price of this material is very low. In this work, it was investigated the use of coal ashes in a composition of refractory insulating brick. In coal combustion process, fly ashes and bottom ashes are generated. Bottom ashes are formed by partially fused ashes that precipitate to the bottom of the boiler, due to their coarser particle size. Therefore, it was analyzed fly ash addition in a refractory body and the addition of bottom ashes, partially replacing chamote (calcinated clay). The results showed that the effect of the ash is small in the fired materials. In terms of technological characterization, the bricks formulates with coal ash were considered suitable to commercial brick standards. Density and thermal conductivity of the refractory bricks with coal ashes had revealed to be similar the commercial products. Then, the use of ash is economical attractive and technical feasible. Translated from Novye Ogneupory, No. 6, pp. 60–63, June 2008.     

粉煤灰轻质隔热耐火砖的研制

利用电厂优质粉煤灰 ,加入少量辅助材料及复合结合剂 ,制成体积密度为 0 .6～ 1.0g/cm的轻质隔热耐火砖。制品掺灰量为 60～ 90 % ,无需粘土结合 ,导热系数小 ,热稳定性好 ,成本低 ,可替代漂珠砖用于冶金、机械、化工等行业     

Utilization of Class C Fly Ash As A Raw Material for Manufacturing of Refractory Materials

There have been increasing efforts to utilize energy by-products( EBP) all over the world. In the Czech Republic fly ash is usually used in ceramic technology,especially in brick manufacturing and for ceramic tiles.The average production of EBP is about 14 million tons per year. The range of potential products,where EBP could be used,is very wide and energy by-products have become an important raw material source. In this paper the attention was focused on class C fly ash and its usage in field of refractory materials. Experimental works were carried out on mixtures with fly ash and clay. There were also tested batches for lightweight fireclay bricks.The maximal amount of CFA should be up to 50%.     

抛光砖废渣制备轻质外墙砖工艺参数的研究

采用抛光砖废渣等工业废渣为主要原料,以高可塑性粘土、黑滑石、钾长石、石英和煅烧氧化铝为辅助原料制备陶瓷轻质外墙砖,研究了抛光砖废渣用量、成型压力以及烧成制度对轻质外墙砖性能和质量的影响。结果表明：随着抛光砖废渣用量增加或成型压力的降低,轻质外墙砖的导热系数提高而抗压强度与容重则降低。通过TG-DSC分析确定了在小于等于...     

抛光砖废渣制备轻质外墙砖工艺参数的研究

采用抛光砖废渣等工业废渣为主要原料,以高可塑性粘土、黑滑石、钾长石、石英和煅烧氧化铝为辅助原料制备陶瓷轻质外墙砖,研究了抛光砖废渣用量、成形压力以及烧成制度对轻质外墙砖性能和质量的影响。结果表明：随着抛光砖废渣用量增加或成形压力的降低,轻质外墙砖的导热系数提高而抗压强度与容重则降低。通过TG-DSC分析确定了在≤750...     

用 BSF 复合矿物掺合料配制 C35路面混凝土的收缩性能研究

研究了以砖粉、粉煤灰和矿渣粉为主要原料开发的BSF复合粉体作为矿物掺合料对混凝土干燥收缩的影响,以及三种原料分别对混凝土干燥收缩的作用机理。试验结果表明粘土砖粉和粉煤灰能小幅的补偿收缩,并且随着其掺量的增加,混凝土收缩减少的幅度也增大;而矿渣粉的掺入会加剧混凝土收缩, BSF复合粉体对混凝土体积稳定性的影响与三种原料的相互作用有关,混凝土中10 nm以下的微孔对干缩的影响最大。     

The role of a coal gasification fly ash as clay additive in building ceramic

The clean coal integrated gasification in combined cycle (IGCC) technology of electrical power generation is different than conventional process in combustible treatment which generates inorganic wastes in the form of glassy slag and fly ash with singular properties. We have studied the fly ash coming from ELCOGAS IGCC power plant as additive to clays for building ceramic fabrication.

The addition of this new kind of fly ash to a clay of medium plasticity to elaborate pressed specimens, that were baked at 900 °C, improves the sintering of the paste and consequently an improvement of absorption, saturation and mechanical properties of the fired bodies, with no negative effects on shrinkage, colour alteration or efflorescence. In contrast, this fly ash does not mend the excessive firing shrinkage when added to a clay of a high plasticity index.     

Morphology and Properties in Blended Cements with Ceramic Wastes as a Pozzolanic Material

This paper describes the research run on ceramic materials, and more specifically fired clay roof tiles, ground to a fineness suitable for use as an active replacement for portland cements (PCs). The utilization of waste products from calcined clay roof tiles as a pozzolanic material in the cement manufacture is studied. One of the first materials used as pozzolans in the history was thermal-treated clay, a material similar to the calcined clay precast elements. For this study, the materials selected are clay products that have been eliminated for different reasons: a wrong temperature inside the kiln, dimensional and mechanical failures, and durability loss. The results showed that these products have good pozzolanic properties; at an early age, the pozzolanic activity was found to be higher than fly ash, although it was lower than silica fume. The morphology of clay tile–PC pastes are similar to the morphology of the pastes containing other pozzolanic materials. Hydrated calcium aluminate products are generated when the preparation method yields less compact pastes with a greater voids' volume to accommodate these products. The hydrated calcium aluminate phases were analyzed using scanning electronic microscopy and X-ray diffraction techniques.     

粉煤灰陶瓷墙地砖的制备工艺及性能研究

以固体废弃物粉煤灰与K2CO3为主要原料,通过预烧处理得到活化的粉煤灰原料,分别在850 ℃、875 ℃、900℃、925℃、950℃度进行常压烧结,制备得到粉煤灰陶瓷墙地砖材料.利用XRD、SEM分别对其物相组成与微观结构进行测试,结合烧成样品的吸水率、体积密度、显微硬度随温度的变化规律,分析了烧结工艺对粉煤灰陶瓷墙地砖性能的影响.研究结果表明:随着烧结温度的升高,样品中液相含量明显增加,在液相流动的作用下,坯体内部的气孔逐渐被填充,固相颗粒被粘结在一起形成连续的整体,从而形成致密的瓷体结构,当烧结温度为925 ℃时,样品的吸水率达到最小值:0.07%,维氏硬度达到最大值:5.9 GPa.而保温时间的增加,液相流动与物质迁移更充分,导致KAlSiO4晶粒尺寸增加,轮廓清晰,但并未对物相及其力学性能产生明显影响.     

Leaching and Solubility Analysis of Porcelain-Recycled Tile Residues in Clay Bricks

In this study, a porcelain tile residue was used to produce clay bricks. The residue was characterized (XRF, PSD, dilatometry, solubility, and leaching analyses) and was added to a brick paste, forming compositions that were extruded, dried, and fired at 1000°C. The fired specimens were tested [compressive strength, shrinkage, apparent density, water absorption, phase analysis (XRD), microstructure (SEM), leaching, and solubility]. The results showed that the porcelain residue was a noninert material. When added to the brick paste, the residue shows an improvement of some properties due to its alkaline content acting as a flux in the clay paste and causing the vitrification of the structure.     

免烧结微生物垃圾焚烧飞灰砖的抗压强度研究

针对当前城市垃圾焚烧飞灰(MSWI)处置费用高昂、环境污染严重等问题,提出一种利用微生物矿化原理制备免烧结垃圾焚烧飞灰砖的方法。通过在飞灰砖固结体中加入微生物菌液,利用微生物诱导碳酸盐沉积原理,实现飞灰中重金属的固化和稳定化。本文以垃圾焚烧飞灰、Ca(OH)₂、砂子、微生物菌液为原材料,通过单因素试验,探究了制备微生物飞灰砖最优的飞灰掺量、菌液浓度、营养液中钙离子浓度。试验结果表明,当飞灰掺量为40%(质量分数),菌液OD₆₀₀值为0.60,营养液中钙离子浓度为0.30 mol/L时,飞灰砖力学性能最优。此时规格为100 mm×100 mm×50 mm免烧结微生物飞灰砖的干密度为1 937.40 kg/m³,抗压强度达到33.90 MPa,并且重金属浸出浓度满足限值要求,实现垃圾焚烧飞灰的资源化利用。     

Fabrication of low to high duty fireclay refractory bricks from lignite fly ash

The development of refractory bricks made of new materials has recently drawn a lot of interest to address sustainability issues. So, in this study, the recycling of lignite fly ash produced by coal-fired thermal power plants has been investigated to make fireclay refractory bricks. The lignite fly ash and ball clay are the primary raw materials characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), X-ray fluorescence (XRF), and differential thermal analysis (DTA). The samples were prepared using a uniaxial hydraulic press, and firing was done in the range of 1000–1200 °C for 2 h. The fired samples were characterized in terms of chemical composition, mineralogical phase, and microstructural using different characterization tools such as XRF, XRD, and SEM. The physical, mechanical, and thermal properties such as linear firing shrinkage, apparent porosity (AP), bulk density (BD), cold crushing strength (CCS), cold modulus of rupture (CMOR), and thermal conductivity of the fired sample were investigated. The linear firing shrinkage, AP, BD, and CCS values were achieved estimated to be 5.32%, 2.10 g m/cc, 15%, and 52 MPa, respectively. The SEM analysis shows dense, rod-like mullite structure and interlocking microstructure of the fired samples. The results were well matched with ASTM standards and commercially available products. So, this promising result indicates lignite fly ash can be used as a potential raw material to produce fireclay refractory bricks.     

Influence of volcanic ash as flux on ceramic properties of low plasticity clay and high plasticity clay of Trinidad

Abstract

Currently there is interest in exploring the commercial viability of using ash from the erupting Soufriere Hills volcano on the island of Montserrat in the eastern Caribbean as a flux component in ceramics. Consequently, the fired characteristics (at 1100°C) of model test pieces fabricated from blends of the ash, covering the range 0–30%, with a low plasticity clay and a high plasticity clay (both kaolinitic) of Trinidad have been investigated. The results show that while 5–10% of the ash has little effect on the fired physical and mechanical properties of the low plasticity clay, 15% and above more than doubles the strength and significantly lowers the porosity. At the same time the linear shrinkage is increased by only a few per cent. On the other hand, addition of the ash to the high plasticity clay appears detrimental. In particular, compared with the properties of the clay without ash, increasing amounts of ash progressively and significantly decrease both the green and fired strength and slightly increase the fired porosity. Further, fracture toughness K_IC measurements suggest that addition of ash above 15% has an embrittling effect. Based on calculation and microscopy, increased critical flaw size with increased ash content seems to account for the deleterious effects of the ash on the fired properties of the high plasticity clay. In turn, the increased critical flaw size is believed to be a consequence of stress induced microcracking on cooling caused by a difference in thermal expansion coefficient between the vitrified clay phase and the fused ash phase.     

免烧结免蒸养粉煤灰砖的力学性能及水化机理

以提取微珠后的粉煤灰残灰为主要原料(掺量为85%),辅以少量的钙质材料及微量的激发剂,通过研究不同原料配方、成型压力、养护方式对粉煤灰砖力学性能的影响,探索免烧结免蒸养承重粉煤灰砖的最佳制作工艺,通过粉煤灰砖的不同龄期的强度及微观结构,分析了粉煤灰残灰的激活及水化机理。     

Insulating silica brick from “Strupets” quartzite deposits

Conclusions Quartzites from the Strupets deposits In the Slivensk area of the Bulgarian People's Republic are suitable materials for producing insulating silica brick with an apparent density of 1.0–1.2 g/cm³ by the combustible additive method.The coke used as the combustible with a high content of ash reduces the refractoriness of the insulating brick. An increase in the content of combustible is connected with a reduction in the apparent density, and a reduction in the strength of the products.We established the possibility of using dinas scrap for producing insulating brick; its effect on the properties of the finished product are of secondary importance.The specific fabrication pressure within the limits investigated can affect the ceramic factors of the finished goods.The properties of the fired specimens correspond to the requirements of the technical specifications of the Bulgarian People's Republic for insulating silica brick.Translated from Ogneupory, No. 7, pp. 59–61, July, 1971.     

Prediction of unburnt carbon in tangentially fired boiler using Indian coals

Accurate prediction of percentage unburnt carbon in fly ash in the case of high ash content Indian coal, at the design stage, is generally difficult. In the present paper, a large number of laboratory test data and site data are used to understand the mechanism of unburnt carbon in fly ash as well as in bottom ash. Rigorous statistical analysis of the performance data taken from tangentially fired boilers shows that empirical correlation between a combination of coal properties and percentage unburnt carbon in fly ash exist. Equations to predict percentage unburnt carbon in fly ash and bottom ash have been proposed.     

Microstructure and chemical degradation of adobe and clay bricks

The environmental degradation of adobe and fired clay brick was studied. Leaching media based on Na₂S₂O₅ solution and deionized water were used. The microstructure of the samples was evaluated by X-ray powder diffraction, nitrogen adsorption–desorption (BET method), Fourier transform infrared spectroscopy and scanning electron microscopy. The predominant phases detected were kaolinite and quartz for both the adobe and fired brick samples. The high surface reactivity, associated with a large amount of OH groups, contributes to the significant degradation of adobe. The fired clay brick showed a significant decrease in the average pore diameter after the first day of the leaching process; its specific surface area exhibited a reduction of about three orders of magnitude. The results of the present investigation contribute to a better understanding of the correlation between structure and leaching behaviour in adobe and clay brick, attending the renewed interest in these materials as environmentally attractive building blocks.     

Dry pressed ceramic tiles based on fly ash–clay body: Influence of fly ash granulometry and pentasodium triphosphate addition

Fly ash from brown coal (70 wt.%) and stoneware clay (30 wt.%) were used for the dry pressed ceramic tiles (according to EN 14411) raw materials mixture. The effects of fly ash milling and pentasodium triphosphate addition as a deflocculant and fluxing agent on the properties of green body (flexural strength, bulk density) and fired body (EN ISO 10545—water absorption, bulk density, true density, apparent porosity, flexural strength, frost resistance) were studied and explained as a function of the firing temperature (1000–1150 °C). Fly ash milling (corresponding to 5 wt.% residue of fly ash grains on 0.063 mm sieve) increased the sintering abilities of the fly ash–clay body. A similar effect was achieved by 1.3 wt.% pentasodium triphosphate (PST) addition with an increase in green body flexural strength and a decrease in water content of the granulate. Fly ash–clay bodies can be frost resistant with water absorption above 10% due to positive pore size distribution, which were examined using the high-pressure mercury porosimetry method.     

利用金陵热电厂脱硫灰制备双免砖的研究

以金陵热电厂所排脱硫灰为主要原料,进行了免烧免蒸砖的研究。采用正交试验方法,设计了脱硫灰、水泥、集料、石膏、石灰的不同配比。试验结果表明,在配比为水泥8％、集料25％、石灰10％、石膏5％、粉煤灰52％时,生产的免烧砖强度最高。同时还研究了不同原材料对免烧砖强度的影响。