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低阶烟煤制取型煤的成型机理研究 总被引:2,自引:2,他引:0
选用水玻璃、膨润土和赤泥三种无机黏结剂,分别以四种不同的掺入量和低阶烟煤粉煤混合制取型煤.对型煤样品进行抗压强度的测定表明,型煤抗压强度随黏结剂掺比增大而增大,其中以膨润土为黏结剂的型煤强度远高于以水玻璃和赤泥为黏结剂的型煤强度,进一步的型煤微观结构电镜分析也证实了以膨润土为黏结剂的型煤其黏结性能相对最好,电镜切片表明,膨润土以朵状凝胶体楔入煤粒孔隙中并在煤粒表面形成整体网状结构.由于低阶烟煤自身的性质,以其制取的型煤往往对成型压力比较敏感,实验表明型煤的冷强度随成型压力的增大先增大后减小,存在一个最优成型压力. 相似文献
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为实现粉煤的综合利用,以城市污泥为黏结剂的基础组分,采用化学方法活化,利用粉煤成型技术制备型煤,对工艺条件进行研究,考查了成型压力、污泥含量、干燥时间对型煤冷压强度和湿压强度的影响,确定了最佳工艺条件。结果表明,污泥含量为12%、成型压力12 MPa、干燥时间8 h时,制得型煤的冷压强度为1 522.5 N,落下强度为97.7%,型煤600℃干馏2 h制得型焦的强度、灰分、挥发分、发热量等主要指标均达到《陕西省地方洁净型煤技术标准》。利用活化污泥可制备出适用于工业生产的洁净型煤。 相似文献
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用半焦粉末制备型煤特性实验研究 总被引:2,自引:0,他引:2
以半焦焦粉为主要原料,采用冷压成型工艺制备型煤.重点研究了黏结剂、原料粒度和水分等因素对型煤性能的影响.结果表明,以有机黏结剂制备的型煤抗压强度最大,发热量高,但热稳定性较差;以无机黏结剂制备的型煤抗压强度低,发热量小,但热稳定性好;采用复合黏结剂可以取长补短,发挥出最佳黏结效果. 相似文献
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无烟煤的物理性质对其型煤抗压强度的影响 总被引:1,自引:1,他引:0
以无烟粉煤为原料,采用有黏结剂冷压成型方法,制备了几种型煤产品,并对无烟粉煤的显微硬度、可磨性、真密度、视密度、孔隙率最高内在水分和孔结构等物理性质进行了分析测试,重点研究了无烟煤的物理性质对型煤抗压强度的影响.结果表明,随无烟煤的反射率、显微硬度、真密度和视密度等指标的增加与可磨性的降低,型煤抗压强度均显示出增加的趋势,这与高压无黏结剂成型时,型煤强度与显微硬度关系相反.无烟煤的物理性质体现了煤的变质程度,因此,型煤抗压强度也与无烟煤的变质程度密切相关.研究结果还表明,不同煤阶无烟煤的孔结构分布和最高内在水分不尽相同,都影响无烟煤被黏结剂黏结的程度,从而影响无烟煤型煤的抗压强度. 相似文献
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为了解决细粒黄金尾矿的堆存对环境的污染和资源浪费问题,以细粒黄金尾矿为主要原料,添加膨润土、粉煤灰制备烧结砖。对原料基本成分分析后,采用模压成型法来制备烧结砖,主要研究焙烧温度、保温时间、以及物料的不同配比对烧结砖性能的影响。结果表明:最佳组成为尾矿75%(质量分数,下同),膨润土15%,粉煤灰为10%;最佳工艺条件为成型水分10%,成型压力20 MPa,焙烧温度1 175 ℃,保温时间50 min。在该条件下制备的烧结砖的抗压强度为38.71 MPa,抗折强度为10.54 MPa,体积密度为1.908 g/cm3,吸水率为3.5%。 相似文献
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为探究冻融循环作用对粉煤灰加固路基土力学性能影响,对冻融循环次数、含水率、粉煤灰掺量不同的盐渍土开展无侧限抗压试验和三轴剪切试验,研究冻融循环后土体的应力-应变曲线、无侧限抗压强度、黏聚力和内摩擦角的变化情况。使用Design-Expert 8.0软件,研究冻融循环次数、粉煤灰掺量、含水率及各因素交互作用对盐渍土力学性质影响的显著性程度。结果表明:多次冻融循环后,盐渍土无侧限抗压强度、黏聚力和内摩擦角均有下降,经历1~7次冻融循环时,土体各力学参数下降速率较快;随着粉煤灰掺量的增加,盐渍土的内摩擦角、黏聚力、无侧限抗压强度和抗剪强度呈现出先升高后下降的变化趋势。基于显著性分析理论,冻融循环次数与含水率的交互作用对盐渍土无侧限抗压强度和黏聚力的影响较为显著,粉煤灰掺量与冻融循环次数的交互作用仅对无侧限抗压强度影响较为显著。为提高路基土强度及抗冻融的能力,加快粉煤灰综合利用进度,根据软件和公式模拟结果,推荐在路基土中依据质量比掺加15%粉煤灰,并将经历7次冻融循环后压实盐渍土的力学指标作为工程设计参考值。 相似文献
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The effect of bentonite, colemanite ore waste (CW), coal fly ash (FA) and coal bottom ash (BA) on the properties of cement and concrete has been investigated through a number of tests. The properties examined include setting time, bending strength, volume expansion, compressive strength and water consistency of the mortar. The result showed that setting time of the cements was generally accelerated when bentonite replaced a part of the cement. Bentonite exhibited a significant retarding effect when used in combination with CW in Portland cement at lower replacement level and showed an accelerating effect at higher replacement level. Although the inclusion of bentonite at replacement levels of 5-10% resulted in an increase in compressive strength at early ages, it decreased the compressive strength when used in combination with other materials. The results obtained were compared with Turkish standards and, in general, were found to be acceptable. 相似文献
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为了研究水泥土在外加剂作用下的强度与渗透特性,综合考虑含水率、水泥掺量、减水剂含量与粉煤灰掺量等因素的影响,基于正交设计方法进行一系列试验研究,得到了龄期为3 d、7 d和28 d时水泥土的无侧限抗压强度和渗透系数,以及各个因素对其影响的规律,并利用SPSS软件对它们之间的关系进行了拟合.试验结果表明:这4种因素对水泥土抗压强度及渗透系数影响的主次顺序均为:含水率→水泥掺量→减水剂含量→粉煤灰掺量.随含水率增加,水泥土抗压强度逐渐降低,渗透系数不断增大;而水泥掺量的影响趋势则与之相反;随试样中减水剂含量增加,其抗压强度和渗透系数分别呈下开口抛物线和"V"形变化,在实际工程中需根据相应工程目标并结合现场试验确定最佳掺入量;在水泥土中掺入适量粉煤灰对其强度无明显影响,但是可降低水泥土的渗透性,在龄期较短时更为显著. 相似文献
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为系统研究粉煤灰掺量、硅灰掺量及养护温度对湿喷混凝土力学性能的影响规律,通过设计正交试验对湿喷混凝土抗压强度进行极差和方差分析。结果表明:湿喷混凝土抗压强度随养护龄期增加而增大,但抗压强度增幅随养护龄期延长而减弱;增加硅灰和粉煤掺量均能有效提高湿喷混凝土抗压强度,但粉煤灰掺量超过10%(质量分数,下同)后,粉煤灰掺量的增加对混凝土后期抗压强度没有显著的影响;三因素对湿喷混凝土抗压强度影响程度顺序为硅灰掺量>养护温度>粉煤灰掺量;湿喷混凝土抗压强度对矿物掺合料的敏感性与养护温度呈正相关,增大养护温度能够提高矿物掺合料对湿喷混凝土抗压强度的改善效果;随着养护温度的提高,团絮状胶凝物质大量生成,水化产物黏结得更为密实,混凝土的抗压强度和承载性能得到进一步增强;构建多元非线性回归模型能够对混凝土抗压强度进行预测,并且湿喷混凝土在硅灰掺量、粉煤灰掺量及养护温度分别为15%、15%和10 ℃时具有最佳的抗压强度。 相似文献
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针对兰州地铁下穿黄河砂卵石地层,在盾构掘进中能更好的控制同步注浆的浆液性能,通过对砂卵石地层同步注浆的浆液性能要求配制8组不同的配合比,试验测试:浆液密度、浆液流动度、浆液塌落度、稠度、凝结时间、水下浇注试验、抗水冲的分散试验、析水率以及试件的抗压强度,得到膨润土可以提高浆液的稳定性;黏土粉的加入,使注浆浆液的粘聚能力增大,提高了浆液整体性和抗水性,但是添加了黏土粉的浆液流动性明显降低;浆液的含水量和黏土粉的含量决定浆液凝结时间和流动性的主要因素.进而得到浆液的配合比为:水25%~30%、膨润土6%、水泥6%~7%、细沙35%~40%、黏土粉与粉煤灰20%~25%.为以后盾构穿越黄河砂卵石地层提供参考. 相似文献
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This paper outlines the preliminary results of a research project aimed at optimizing the fly ash content in concrete. Such fly ash concrete would develop an adequate 1-day compressive strength and would be less expensive than the normal Portland cement concrete with similar 28-day compressive strength. The results show that, in a normal Portland cement concrete having a 28-day compressive strength of 40 MPa, it is possible to replace 50% of cement by a fine fly ash (∼3000 cm2/g) with a CaO content of ∼13%, yielding a concrete of similar 28-day compressive strength. This concrete can be designed to yield an early-age strength of 10 MPa and results in a cost reduction of about 20% in comparison to the control concrete. In a case of a coarser fly ash (∼2000 cm2/g) with a CaO content of ∼4%, substitution levels of cement by this ash could be from 30% to 40%. This concrete yields a 1-day compressive strength of 10 MPa and a 28-day compressive strength similar to that of the control concrete. The total cost of this concrete is about 10% lower than that of the control concrete. 相似文献
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膨润土增强的黄土和红土的性质 总被引:2,自引:0,他引:2
Loess and laterite distributed widely in the northern and southern China cannot be directly used as the natural barrier to isolate the solid waste because of their high hydraulic conductivity. In this paper, they are enhanced by bentonite to improve their hydraulic performance. The impact of bentonite content and water content on compressive strength of the compacted soil was investigated. The effects of bentonite content, water content, dry density and hydraulic gradient on the hydraulic conductivity were studied in detail. For the laterite and the laterite with 8% of bentonite, the experimental results of hydraulic conductivity can be applied in the engineering design. However, for the loess and the bentonite enhanced loess, those of hydraulic conductivity can not be directly applied in the engineering design because their hydraulic performance does not comply with the Darcy‘s law. These experimental results have to be carefully modified before application. 相似文献