CaCO3在分解炉中的反应特性

实验研究表明CaCO3颗粒在分解炉中的反应受一定温度和CO2分压的影响.定量反应二者关系,以及确定CaCO3颗粒在分解炉中的分解时间是本文研究的重点,同时也对提高分解率,降低热耗的方法进行了探讨.     

CaCO3在分解炉中反应特性

实验研究表明CaCO3颗粒在分解炉中的反应受一定温度和CO2分压的影响，定量反应二者关系，以及确定CaCO3颗粒在分解炉中的分解时间是本文研究的重点，同时也对提高分解率,降低热耗的方法进行了探讨。     

平衡分解率模拟分解炉工艺特性

应用高温，悬浮态气固反应试验台测得的碳酸钙平衡分解率，建立了分解炉的数学模型，并针对某水泥厂的物料及工艺参数进行了分解炉工艺特性模拟实验，提出了平衡因子评价实际分解炉状态的概念，其模拟结果与实际情况有很好的可比性，这种模型可用于各类类型分解炉的工艺特性研究，工业设计和生产控制。     

水泥分解炉中石灰石分解特性的数值研究

通过建立石灰石悬浮态分解的数学模型,并结合水泥工业预分解炉的实际情况,系统分析了温度、CO2含量、粒径和气流速度等因素对石灰石分解的影响.计算结果表明,对于粒径小于65μm的颗粒,其反应过程受化学反应控制,随着粒径的进一步增大,传质因素的影响逐渐变得严重.温度是分解的首要影响因素,CO2含量和颗粒粒径的影响随着温度的升高迅速减弱,气流速度对分解的影响则可以忽略.分解反应后期进行缓慢,在低温(T<900℃)下,入窑分解率一般控制在85%左右较为合适.这些结论对工业分解炉的设计和操作有一定的指导意义.推导出的公式可以计算各种条件下石灰石的分解时间.     

矩形通道内CaCO_3污垢特性研究

采用数值模拟方法研究了矩形通道内CaCO3污垢的沉积过程,分析了CaCO3溶液的浓度、速度、温度对污垢沉积率、剥蚀率与污垢热阻的影响。结果表明,CaCO3在矩形通道内的沉积率、剥蚀率与污垢热阻随入口浓度的增大而增大,随着入口速度的增大而增大,但是随入口溶液温度的增大而减小。     

分解炉内煤的燃尽特性研究

煤粉的燃尽时间已成为进行分解炉设计的重要参数。针对水泥分解炉的低燃烧工况,根据囊灰缩核模型及有关理论,采用失重分析法及扫描电镜,进行煤的燃尽特性实验方法、及煤焦燃尽时间与煤质之间的关系探讨,力求寻找到有关规律。提出的煤质评判指标（指火指数、燃尽指数）与实验方法,较好的定量反映出各煤样的燃尽特性。同时还根据水泥厂的实际实验条件,寻找出着火温度、燃尽时间与煤工业分析值之间的关系式,从而可以根据煤的工业分析结果对煤质进行预测。     

涡流发生器对CaCO_3污垢特性影响的实验研究

本文对直排浮点型涡流发生器的CaCO_2污垢特性进行了实验研究,通过称重法(计算试片单位面积的污垢沉积量)对不锈钢平板和几种不同浮点尺寸、间距的涡流发生器的污垢特性进行分析比较。结果表明:直排浮点型涡流发生器试片的污垢量到渐近值的时间比平板短,污垢增长速度较平板慢。直排浮点型涡流发生器当浮点直径5 mm、列间距15 mm的试片污垢量渐近值最小,污垢生长期也较长,抗垢性好。     

萃取沉淀法制备纳米CaCO_3的研究

利用2-乙基己基膦酸单2-乙基己基脂(P507)在常温条件下萃取CaCl2溶液中的Ca2+,再用饱和(NH4)2CO3溶液从负载Ca2+溶液中进行反萃制备CaCO3沉淀,并对该纳米制备方法的生成机理进行了讨论。TEM和XRD测试表明:粒子基本呈球形,粒径平均约为30~40nm。此实验方法为纳米CaCO3的制备提供了新途径。     

纳米CaCO_3表面有机化处理

采用水性体系对纳米CaCO3进行表面处理。XPS、FT-IR、TGA分析表明,硅烷偶联剂KH-570能与纳米CaCO3生成Si O Ca键,从而化学健接到CaCO3粒子表面。TEM分析表明,改性后的纳米CaCO3能有效地以初始粒子结构进行分散。     

Preparation of calcium carbonate particles coated with titanium dioxide

The preparation of a new mineral composite material,calcium carbonate particles coated with titanium dioxide,was studied.The mechanism of the preparation process was proposed.The new mineral composite material was made by the mechanochemical method under the optimum condition that the mass ratio of calcium carbonate particles to titanium dioxide was 6.5:3.5.The mass ratios of two different types of titanium dioxide(anatase to rutile) and grinding media to grinded materials were 8:2 and 4:1 respectively,and ...     

多孔超细碳酸钙微球的制备

采用乳状液膜与共沉淀结合法制备多孔超细碳酸钙微球,考察了不同反应条件对碳酸钙微球形貌的影响.通过X射线衍射、扫描电子显微镜及激光粒度仪对所得的碳酸钙微球的晶体组成、形貌以及粒度进行了表征.结果表明,超细碳酸钙微球生成的最佳工艺条件为:CaCl2溶液浓度0.1mol/L、吐温-80加量4mL、超声乳化5min、搅拌反应3h,此工艺条件下获得多孔碳酸钙微球粒径在2~10μm,球形圆整,且组成为球霰石与方解石的共混体.     

Numerical Simulation of the Gas-solid Two-phase Flows in a Precalciner

The gas-solid two-phase flous of the precalciner were simulated by different multiphase models,such as mixture model,the Enderium model,including mixture and dispersed,and discrete phase model（DPM）,The results of the different multiphase models were analyzed and compared.showing the rationality of the diffusion and mixture of the cenment raic meals and coal poroder some extent Moreover,the results also shose the rationality of the given inlets parameters of actual process of the precalciner.     

Preparation and characterization of three-dimensional chrysanthemun flower-like calcium carbonate

Calcium carbonate with three-dimensional chrysanthemun flower-like structure was successfully prepared from calcium chloride and sodium carbonate ethanol/water mixed solution by a simple precipitation method,using trisodium citrate as crystal modifier.The experimental results show that the three-dimensional structure of chrysanthemun flower-like calcium carbonate is built up with several symmetrical micrometer multi-layer petals arranged around the multi-layer pancake-liked center,and the micrometer center and petals are assemblied by a large number of nanometer spherical particles with size 10-20 nm.It is found that the amount of trisodium citrate,the ethanol volume content has an important influence on the formation of this morphology.A possible mechanism is proposed to explain the formation of three-dimensional chrysanthemun flower-like calcium carbonate according the results.Scanning electron microscopy(SEM),X-ray powder diffraction(XRD),flourier transform infrared spectroscopy(FT-IR),thermogravimety analysis(TG),transmission electron microscopy(TEM) equipped with energy-dispersive X-ray(EDX),and selected area electron diffraction(SAED) were used to characterize the crystals.     

不同品种碳酸钙填充PVC性能的研究

为了考察不同品种碳酸钙对PVC/CaCO3复合材料性能的影响,采用双螺杆挤出机挤出造粒、注塑机注塑成型,通过万能试验机和简支梁冲击试验机检测其力学性能,使用SEM观察断面微观形貌.结果表明:纳米钙和包覆钙的填充效果最好,分别使PVC的拉伸强度增加19%和17%,PVC的无缺口冲击强度增加4倍以上,分别达54.05和51.67kJ/m2;PVC的缺口冲击强度增加3倍左右,分别达28.94和22.59kJ/m2;复合钙的填充效果居中,重钙和轻钙最差.多种CaCO3填充PVC后,PVC原来平整的颗粒轮廓发生了变化,纳米钙和包覆钙形成了大量高低不平而圆润的表面,重钙和轻钙形成较多的裂纹和空穴.     

Modification of nanometer calcium carbonate for water-borne architectural coatings

A kind of modifier was synthesized to modify the surface of nanometer calcium carbonate (abbreviated as nano-CaCO3), which is used in architectural coatings. The modification technology of the nano-CaCO3 was studied through orthogonal experimental methods. The factors studied were rotation speed, modifier dosage, emulsification temperature, emulsification time and heat aging time after emulsification. Optimized conditions for modification of the surface were rotation speed 16000 r/min; modifier dosage 3%; emulsification temperature 75 ℃; emulsification time 60 min and aging time 40 min. The modified nano-CaCO3 was also studied by size-distribution measurements, transmission electron microscopy, infrared spectroscopy and thermal analysis. The results show that the size distribution of the modified nano-CaCO3 is uniform and that there are chemi-sorption and physi-sorption between the nano-CaCO3 and the modifier. Compared to traditional architectural coatings without nano-CaCO3, the nanometer composite coatings are obviously improved in respect to dirt resistance, scrub resistance, thixotropy, water resistance, alkalinity resistance and aging resistance.     

羧甲基纤维素钠作用下CaCO3微球的制备及表征

为获得粒径均匀、表面光滑的CaCO3微粒,研究羧甲基纤维素钠(CMC)作用下CaCO3微球的制备及性能表征.考察CMC质量浓度、搅拌速度、沉积反应温度对CaCO3粒子形貌的影响,确定合成CaCO3微球的较优实验条件,并用粒度分析仪、X射线衍射仪(XRD)、热重分析仪(TGA)、Zeta电位仪对性能进行表征,提出CMC作用下CaCO3微球生长机理.结果表明CMC质量浓度ρ(CMC)为0.5g/L时可得到表面光滑的球文石型CaCO3,粒径分布在6～8μm,CMC的质量分数w(CMC)为5.12%,表面电位为-37.3mV.这种形态的颗粒可适用于生物、医药等领域.     

砂姜黑土区旱作物土壤墒情指标研究

文章利用五道沟水文水资源试验站试验研究资料,分析了砂姜黑土旱作物生长的适宜土壤含水量范围,同时结合研究区包气带土壤水分运移的特点研究了土壤墒情指标的变化特性.试图为制定合理的旱作物农业灌溉制度提供技术支持.