预分解技术在硫铝酸盐水泥生产中的应用

硫铝酸盐水泥的生产除少数厂家采用预热器煅烧工艺,大部分企业仍采用干法中空窑生产工艺,煤耗高,排放超标,污染大,加上管理落后,生产质量不稳定。采用预分解技术改造硫铝酸盐水泥生产线时,必须结合硫铝酸盐生产工艺参数设计分解炉、预热器,应重视冷却机、煤粉计量秤和燃烧器的选型。实践证明,预分解技术的应用,使硫铝酸盐水泥的生产环境、质量和能耗都得到了较大的改善。     

超早强硫铝酸盐水泥胶砂的制备与性能研究

通过加入研配的硫铝酸盐水泥专用复合外加剂,配制出早期强度高,流动性好,凝结时间适中的硫铝酸盐水泥基材料.并对其强度、粘结性、抗裂性、体积稳定性、抗冻性、抗硫酸盐侵蚀性能等进行研究.研究结果表明:制备的硫铝酸盐水泥胶砂4h和ld抗压强度可达43.7 MPa和54.4 MPa,具有良好的抗冻性、抗硫酸侵蚀性能,并能与普通硅酸盐水泥胶砂很好的粘结.     

硫铝酸盐水泥基混凝土抗碳化性能的研究

主要研究了水灰比、标准养护龄期、掺合料掺量对硫铝酸盐水泥基混凝土抗碳化能力的影响,并与普通硅酸盐水泥基混凝土抗碳化能力进行了对比,采用SEM和XRD分析进行微观性能测试.研究结果表明:硫铝酸盐水泥基混凝土抗碳化能力随着水灰比的减小而增加;随着标准养护龄期的延长而增大;掺合料的加入可以提高其抗碳化能力,其最佳掺量为20%.相同条件下,硫铝酸盐水泥基混凝土抗碳化能力高于普通硅酸盐水泥基混凝土抗碳化能力.     

硫铝酸盐水泥性能特点与改性技术研究现状

为了进一步解决硫铝酸盐水泥水化热集中、凝结时间难以调控和后期强度易倒缩等问题,从改善硫铝酸盐水泥性能的角度出发,分析了硫铝酸盐水泥的水化机理和应用技术难点,论述了硫铝酸盐水泥目前常用的四种改性措施,以及各种改性措施的改性机理和改性效果,最后指出现有硫铝酸盐水泥的发展方向。     

阿利特-硫铝酸盐水泥研究现状

水泥是世界上用量最大的人造建材之一,他不但大量应用于工业与民用建筑,还广泛用于交通,城市建设、农林、水利以及海港工程等.21世纪水泥工业仍占有重要的基础地位,水泥材料仍然是重要的建筑材料之一.进一步提高水泥性能、节约能源、节约资源、保护环境、走可持续发展的道路是水泥工业发展的方向和目标.     

铝酸盐水泥熟料筛分试验研究

铝酸盐水泥是配制不定型耐火材料的良好结合剂．生产其熟料，国外主要采用熔融法，我国则主要采用回转窑烧结法。长铝公司水泥厂是我国最早采用回转窑烧结法生产铝酸盐水泥的厂家．其生产工艺流程为：矾土、石灰石→配料混合粉磨→生料→成球—煅烧→熟料→粉磨→铝酸盐水泥；其主导产品为CA50水泥。多年来，产品质量好，市场占有率高。为了使铝酸盐水泥大批量走向国际市场。使产品的质量向国际先进水平靠拢．在改进生产工艺、提高熟料质量的基础上．我们又进行了铝酸盐水泥熟料的筛分试验研究，取得了明显效果并已应用于生产。     

几种外加剂对硫铝酸盐水泥性能的影响

研究了高浓高效减水剂FDN、缓凝剂H3803和四种早强促凝组分(Li2CO3，NaNO2，Al2SO4和Na2SO4)对硫铝酸盐水泥标准稠度、凝结时间以及抗压强度的影响。结果表明，高效减水剂FDN与硫铝酸盐水泥相容性很好，减水效果明显；硼酸对硫铝酸盐水泥的缓凝效果不稳定，但通过复掺早强促凝组分能改善其缓凝效果和早期强度，且适量的硼酸能提高水泥浆的后期强度。碳酸锂对硫铝酸盐水泥有显著的促凝作用，但对后期强度不利。     

洗衣粉及去污力测试方法修订和《果蔬清洗剂》国家标准制定研讨会召开

为执行国家标准化管理委员会关于国家标准制定、修订计划的最新安排,全国表面活性剂和洗涤用品标准化技术委员会秘啪处于2008年3月19日在太原召开了关于GB／T13171-2004《洗农粉》、GB／T13174-2003《衣料用洗涤剂去污力及抗污渍再沉积能力的测定》和GB／T15815-1995《衣料洗涤剂性能比较试验循环洗涤白棉对照布法》3项国家标准的修订起草,     

铝酸盐水泥熟料对粉煤灰硅酸盐水泥性能的影响

以铝酸盐水泥熟料、硅酸盐水泥熟料和粉煤灰为原料,探讨了掺加少量铝酸盐水泥熟料对硅酸盐水泥及粉煤灰硅酸盐水泥复合体系水化、凝结和硬化性能的影响。结果表明,在硅酸盐水泥及粉煤灰硅酸盐水泥中掺加铝酸盐水泥熟料,可以明显缩短水泥的初、终凝时间,但复合体系的需水量增加;掺加少量铝酸盐水泥熟料(≤3%)可明显提高硅酸盐水泥的早期强度,但后期强度(28d)有所降低;当铝酸盐水泥熟料的掺量达5%时,水泥的各龄期强度均明显降低。少量铝酸盐水泥熟料掺加到粉煤灰硅酸盐水泥中,复合体系的各龄期强度都明显提高,且早期强度的提高幅度较大。     

Supercritical carbonation of calcium aluminate cement

The microstructural changes occurring during supercritical carbonation (scCO₂) of calcium aluminate cement (CAC) and changes to its strength have been investigated. Cylindrical specimens of CAC cured at different temperatures were prepared and then subjected to scCO₂. It is shown that CAC carbonation in supercritical conditions is accelerated with a positive effect on the compressive strength. Due to the scCO₂ treatment, both conversion and alkaline hydrolysis are avoided. The best behaviour of the studied specimens was attained for samples cured at 25 °C. The residual compounds after the scCO₂ process, i.e. monocalcium aluminate, calcium carbonate and aluminium hydroxide are durable in normal ambient conditions. Complete carbonation of CAC is particularly important for the reinforcement of CAC with polymer fibres to improve its mechanical strength.     

Kinetic modeling of calcium aluminate cement hydration

The hydration of iron-rich calcium aluminate cement (CAC) has been investigated by differential calorimeter and quantitative powder X-ray diffraction (QXRD). A simplified stoichiometric model of early age CAC hydration based on reaction schemes of the principal mineral monocalcium aluminate was employed. The CAC characteristic feature of retardation of nucleation and growth mechanism with temperature requires employing more than one kinetic mechanism to describe the resulting complex hydration kinetics. This paper proposes a single equation kinetic model of CAC hydration which comprises simultaneously three main mechanisms: nucleation and growth, chemical interaction and mass transfer. A gradual change between kinetic mechanisms was grasped with a reasonable inter-dependency of the kinetic parameters. The overall hydration kinetics was described relative to the amount of the both reactants, cement and free water.     

铝酸盐水泥复合普通硅酸盐水泥对砂浆早期抗冻性能的影响

研究了早期受冻环境下铝酸盐水泥复合普通硅酸盐水泥砂浆试件的力学性能及其微观形貌的变化。结果表明：纯铝酸盐水泥体系具有良好的早期抗冻性能，但其与普通硅酸盐水泥复合时，普通硅酸盐水泥掺加比例0~70%时，其早期抗冻性能会有明显下降趋势；而在70%~100%时又呈现上升趋势，但增加幅度较小。铝酸盐水泥低掺量掺入会延迟硅酸盐水泥的水化，导致其复合体系早期抗冻性降低。     

铝酸钙水泥对刚玉基浇注料性能的影响

以电熔白刚玉颗粒及细粉为主要原料,α-Al2O3微粉、铝酸钙水泥以及Alphabond300为结合系统,研究了铝酸钙水泥加入量(质量分数分别为0、0.75%、2.25%和3.75%)对刚玉基浇注料性能的影响。结果表明:1)水泥的加入使浇注料基质的粘度增大,浇注料的流动性降低。2)随着水泥加入量的增加,110℃以及800℃处理后的冷、热态抗折强度均逐渐提高;1 100℃、1 400℃和1 600℃烧后的冷、热态强度均先降低后升高,其中水泥加入量(质量分数,下同)为0.75%时值最小。3)随着水泥含量的增加,浇注料抗热震性提高。4)少量水泥的加入使浇注料的抗渣性能降低,进一步增加水泥加入量,浇注料的抗渣性能逐步改善;在本试验范围内,水泥加入量为3.75%的浇注料和不含水泥的浇注料抗渣性能基本相当。     

Porosity-strength relation in calcium aluminate cement pastes

The compressive strength and the volume porosity of calcium aluminate cement pastes have been studied in order to connect their relationship. The influence of mass fraction of lithium carbonate on compressive strength and porosity of calcium aluminate cement (CAC) has been investigated at different water-cement (w/c) ratios. The functions proposed in the literature for different technical materials were tested on obtained strength and porosity data. Those functions have been a base for further development of more general functional dependence of strength and porosity for cement materials. Thus, we propose the following equation to relate the strength and porosity for CAC pastes:

     

Thermal properties of hydrating calcium aluminate cement pastes

As the hydration of calcium aluminate cements (CAC) is highly temperature dependent, yielding morphologically and structurally different hydration products that continuously alter material properties, a good knowledge of thermal properties at early stages of hydration is essential. Thermal diffusivity and thermal conductivity during CAC hydration was investigated by a transient method with a numerical approach and a transient hot wire method, respectively. For hydration at 15 °C (formation of mainly CAH₁₀), thermal diffusivity shows a linear decrease as a function of hydration degree, while for hydration at 30 °C there is a linear increase of thermal diffusivity. Converted materials exhibited the highest values of thermal diffusivities. The results on sealed converted material indicated that thermal conductivity increased with an increase in temperature (20-80 °C), while thermal diffusivities marginally decreased with temperature. The Hashin-Shtrikman boundary conditions and a simple law of mixtures were successfully applied for estimating thermal conductivity and heat capacity, respectively, of fresh cement pastes.     

水泥工业几种CO2捕获工艺介绍

详细介绍了MEA化学吸收法、纯氧燃烧法、冷却氨水法、膜分离法、分体式钙循环法和集成式钙循环法6种水泥厂可行的CO2捕获技术的工艺流程、原理以及对水泥生产可能产生的影响。实践证明，MEA化学吸收法是可行的，但不一定是最节能的。从理论上讲，这几种CO2捕获方法技术上都是可行的，但捕获效率、能耗、经济效益等可能会有差异。     

水热合成-低温煅烧活化低钙铝酸盐水泥的研究

采用Al2 O3和CaO为原料 ,在实验室常压下水热合成水化铝酸钙 ,然后低温煅烧制备活化低钙铝酸钙水泥。结果表明 :可制备以CA2 为主的低钙铝酸盐水泥 ,降低熟料烧成温度 ,产品较传统烧结法产品活性高、强度高