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填料碳酸钙的制备及其形状与晶型控制研究进展 总被引:6,自引:2,他引:4
介绍了碳酸钙研究的新进展,主要讨论了普通碳酸钙,碳酸钙晶须和纳米碳酸钙的制备方法和机理,以及碳酸钙晶体的形状与晶型控制。 相似文献
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碳酸钙在我国橡胶工业中的应用和发展 总被引:4,自引:2,他引:4
介绍了我国碳酸钙品种,性能及在橡胶工业中的应用和发展。碳酸钙分为重质碳酸钙,轻质碳酸钙和活性碳酸钙[主要指超细活性碳酸钙(又称纳米碳酸钙)],广泛应用于轮胎,胶管,胶带,胶鞋,电线电缆,密封制品,胶数量级和胶布等橡胶制品中,采用先进的表面改性方法和开发多品种,针对性强,性能优异的改性剂,以使纳米碳酸钙真正发挥纳米级粒子的作用,以及扩大超细活性碳酸钙在轮胎和艳色橡胶制品中的应用是扩大碳酸钙在橡胶工业中应用的有效途径。 相似文献
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世界碳酸钙工业发展迅速,产能不断增加,首先介绍了近几年来重质研磨碳酸钙(GCC)产业的发展概况,重点介绍了中国、日本、马来西亚、韩国、泰国的GCC产业及国际著名GCC生产公司在中国的经营情况。其次介绍了世界轻质沉淀碳酸钙(PCC)的市场概况及国外大型PCC生产公司的基本情况。最后,重点介绍了中国大陆地区的碳酸钙生产与市场情况,并通过分析近几年中国碳酸钙产品的进出口数量及价格情况指出,开发适合碳酸钙用户需求的新产品、新技术,参与国际竞争是今后中国碳酸钙生产企业的发展方向。 相似文献
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研究了以碳酸钙为主的无机填料对聚丁二烯型PU[又称端差劲基液体聚丁二烯(HTLPB)型PU,简称HTLPB型PU]的补强作用。结果表明,经活化处理和未经活化处理的碳酸钙,陶土,玻璃纤维和白炭黑对聚丁二烯型PU均具有补强作用,其中碳酸钙,尤其是活性碳酸钙的补强效果显著;碳酸钙分次加入,且预聚物的游离-NCO质量分数为0.03-0.06时补强效果更佳;普通碳酸钙的用量和活性碳酸钙的用量分别不宜超过12和20份。 相似文献
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为避免温室效应带来的负面影响,CO2减排已成为目前的当务之急。CO2矿物碳酸化作为一种有潜力的CO2减排技术,受到了学者们的广泛关注。CO2矿物碳酸化方法主要包括直接干法碳酸化、直接湿法碳酸化以及间接碳酸化等不同工艺过程。目前,CO2直接或间接碳酸化方法面临的关键挑战是提升CO2碳酸化反应动力学特性;反应速率慢、碳酸化效率较低是当前该技术的主要问题。传统CO2胺类化学吸收法具有吸收速率快、吸收容量大和吸收剂能循环再生的优点,但能耗和运行成本较高。将CO2胺类化学吸收法与CO2碳酸化过程结合而开发的CO2吸收-矿化一体化技术(IAM)不仅解决了传统工艺高能耗、低转化率的问题,而且使工艺流程简化、成本降低,有利于应用于工业化。本文主要综述了近年来CO2矿化技术的研究进展,对比了各种工艺技术路线的不同特点,并分析指出加强对IAM工艺反应机理的研究以及开发出高效、经济的吸收剂和矿化原料,将是该工艺未来研究的重点和关键。 相似文献
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研究碳酸化度、反应温度、溶液中氨浓度和硫酸根离子浓度等对芒硝氨盐水溶液碳酸化过程速度的影响,并与氯化钠氨盐水溶液碳酸化过程进行比较。研究结果对芒硝联产纯碱和硫酸铵新工艺的研究和开发具有指导和参考意义。 相似文献
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面对温室效应带来的生态灾难,利用各种技术封存固定CO2成为了关键,CO2矿物封存是其中最环保、最安全、最永恒的CO2固定方式。本文从封存方案、反应机理及碳化原料三方面详细介绍了CO2矿物封存技术的基本原理,并全面概述了CO2矿物封存的技术路线,其中包括直接碳化路线以及以酸浸出工艺、熔盐碳化工艺、铵盐浸出工艺以及生物浸出工艺为代表的间接碳化路线。同时结合国内外研究进展分析了各种CO2矿物封存技术的优缺点及其产业化前景,并提出今后我国CO2矿物封存技术研究和发展应更加注重从资源综合利用的角度考虑,将CO2看做是廉价碳资源材料,积极推进碳捕获、利用与封存项目的实施。 相似文献
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We have studied the carbonation process in different types of mortars, with and without pozzolana or air-entraining additives, subject to a CO2-rich atmosphere and compared the results with those of similar naturally carbonated mortars. We used X-ray diffraction technique to demonstrate that high CO2 concentrations favour a faster, more complete carbonation process with 8 days being sufficient to convert portlandite into 90 wt.% calcite. Full carbonation, however, is not reached during the life-span of the tests, not even in forced carbonation experiments. This could be due to at least one of the following phenomena: a premature drying of samples during carbonation reaction, the temperature at which the carbonation process was carried out or the reduction of pore volume occupied by newly formed calcite crystals. This last option seems to be the least probable. We observed a more prolific development of calcite crystals in the pores and fissures through which the carbonic anhydride flows. Under natural conditions, carbonation is much slower and similar levels are not reached for 6 months. These differences suggest that the carbonation process is influenced by the amount of CO2 used.
Both the mineralogy and texture of mortars vary depending on the type of additive used but the speed of the portlandite–calcite transformation does not change significantly. Pozzolana produces hydraulic mortars although the quantity of calcium aluminosilicate crystals is low. The air-entraining agent significantly alters the texture of the mortars creating rounded pores and eliminating or reducing the drying cracks. 相似文献
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对普通混凝土及掺和料混凝土进行了快速碳化试验,测试了各碳化龄期混凝土pH值,研究了碳化过程中混凝土pH值沿深度变化规律.结果表明:水胶比对混凝土碳化过程中pH值的变化影响最大,降低混凝土水胶比可以有效提高混凝土的抗碳化能力,减小混凝土的部分碳化区长度;矿物掺合料的引入对混凝土pH值也有较为显著的影响,采用合理的掺量后,掺合料混凝土不仅具有较好的抗碳化能力,还可以大大提高水泥取代量,具有良好的经济效益. 相似文献
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Permeability characteristics of carbonated concrete considering capillary pore structure 总被引:3,自引:0,他引:3
During carbonation process, the calcium phases present in cement are attacked by CO2 and converted into CaCO3 and the permeability of concrete is changing due to the change in porosity. The rate of carbonation depends upon porosity and moisture content of the concrete. Especially in underground reinforced concrete structures, the interior portion of concrete surface may be exposed to carbonation and the exterior portion of concrete surface exposed to wet soil or underground water. As carbonation proceeds from outer surface into internal portion of concrete, microstructure is also changed continuously from outer surface into internal portion of concrete. Even the deteriorations in the structures due to the carbonation have been reported more, research on permeability characteristics of concrete considering carbonation and micro-structural information is very scarce.In this study, the permeability coefficient in carbonated concrete is derived by applying a capillary pore structure formation model in carbonated cement mortar and assuming that aggregates do not affect carbonation process in early-aged concrete as a function of porosity. The permeability obtained from the micro-level modeling for carbonated concrete is verified with the results of accelerated carbonation test and water penetration test in cement mortar. 相似文献
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轻质碳酸钙碳化新工艺 总被引:7,自引:2,他引:7
提出了喷射碳化新工艺,介绍了设备流程、原理。测定结果表明:新工艺具有投资少、能耗低、产品质量好、易于操作等特点,还对碳化过程微观机理进行了探讨。 相似文献
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超声波强化钙基废渣碳酸化固定CO2的性能 总被引:1,自引:1,他引:0
钙基废渣碳酸化固定CO2可实现CO2的永久封存,并可实现CO2原位固定,但苛刻的反应条件、过慢的反应速率是困扰该技术发展的瓶颈。对超声波作用下的钙离子浸出及其碳酸化反应特性进行了实验研究,并与搅拌浸出过程进行了对比,考察了浸出条件的影响及其碳酸化反应过程中溶液pH值与电导率变化特性,对碳酸化反应产物进行了XRD、SEM和TGA分析。结果表明,超声波可有效促进Ca2+从钙基废渣中浸出,其促进效果与废渣种类、浸出时间、超声波功率、浸取剂pH值、浆液存放量和废渣粒度等有关,钢渣和电石渣的含钙量、浸出率和超声波强化效果都较其他废渣高;钙离子浸出浓度随超声波功率的增强而增多;浸取剂pH值越低,浸出浓度越高;废渣粒度越高,超声波作用越明显。超声波对碳酸化反应也有强化效果,与机械搅拌相比,在超声波作用下固碳率更高,碳酸化反应程度更高。 相似文献
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Magnesium Hydroxide Dehydroxylation/Carbonation Reaction Processes: Implications for Carbon Dioxide Mineral Sequestration 总被引:1,自引:0,他引:1
Hamdallah Béarat Michael J. McKelvy rew V. G. Chizmeshya Renu Sharma Ray W. Carpenter 《Journal of the American Ceramic Society》2002,85(4):742-748
Gas-phase magnesium hydroxide carbonation processes were investigated at high CO2 pressures to better understand the reaction mechanisms involved. Carbon and hydrogen elemental analysis, secondary ion mass spectrometry, ion beam analysis, X-ray diffraction, and thermogravimetric analysis were used to follow dehydroxylation/rehydroxylation/carbonation reaction processes. Dehydroxylation is found to generally precede carbonation as a distinct but interrelated process. Above the minimum CO2 pressure for brucite carbonation, both carbonation and dehydroxylation reactivity decrease with increasing CO2 pressure. Low-temperature dehydroxylation before carbonation can form porous intermediate materials with enhanced carbonation reactivity at reduced (e.g., ambient) temperature and pressure. Control of dehydroxylation/rehydroxylation reactions before and/or during carbonation can substantially enhance carbonation reactivity. 相似文献