重质碳酸钙生产现状及其发展

综述了以方解石、石灰石、大理石、白垩等为原料 ,经干法或湿法研磨制造重质碳酸钙的国内外生产现状、应用领域 ,探讨了采用湿法研磨及改性新工艺和先进研磨设备 ,开发超细重质碳酸钙系列产品 ,生产粘接剂和密封剂、造纸、医药、日化、塑料、涂料等专用重质碳酸钙系列产品的市场需求和企业效益     

重质碳酸钙在超细粉碎中的多维分形特征

为了研究重质碳酸钙颗粒在超细粉碎过程中的分形维数以及多维分形特征与研磨时间的关系,对重质碳酸钙颗粒进行湿法研磨,提取不同研磨时间的颗粒,测量其粒度分布,并利用单一分形法和多维分形法计算样品的分形维数,建立分形维数与研磨时间的拟合曲线。结果表明:相对于单一分形法,多维分形法更能准确地描述颗粒的尺寸分布状态;通过分形维数与研磨时间拟合曲线中的峰值,可以判断颗粒的最佳研磨时间范围,这与实验中重质碳酸钙颗粒样品的最佳研磨时间60 min相符,从而优化颗粒超细粉碎过程中的研磨时间参数,减少能源消耗。     

超细改性重质碳酸钙制备及在PVC塑料制品中的应用

作者对超细改性重质碳酸钙填料在PVC硬质塑料制品中的应用进行了试验研究，在清华大学工程力学系研制的干式超细研磨粉碎机上完成了重质碳酸钙的超细粉碎和改性料的制备，将这种填料添加到超高分子量PVC中制成标准试样。结果表明：试样缺口冲击强度大于7kJ／m2；当该填料填充量为70phr时，拉伸强度大于20MPa，远优于添加普通重钙填料的结果。本文对在不同增塑剂、偶联剂用量下超细改性重质碳酸钙填料填充量对硬质PVC塑料制品力学性能的变化进行了分析。     

大型超细搅拌磨机的研制和应用

介绍了LXJM大型超细搅拌磨机的基本结构特点和工作原理,从筒体、搅拌器和传动装置等方面优化设计了超细立式搅拌磨机,提出了最佳的磨机工艺流程,并应用在造纸涂布用亚微米重质碳酸钙的湿法超细加工中,将所生产的产品与国外同类产品进行了比较,产品满足造纸工业的要求。     

干法介质研磨方式超细粉体加工系统的研究

超细化处理是工业原料深加工过程中的重要工序,解决大处理量超细粉碎系统的工艺设计问题是非金属矿物加工行业迫在眉睫的任务。通过分析介质研磨方式的球磨机、振动磨和干法搅拌磨与超细分级机工作原理的特点,确定由它们组成闭路超细粉碎—分极—改性系统的可行性。结合作者多年的工作实践经验,介绍了这种超细粉碎系统用于重质碳酸钙超细加工的工艺参数选定和特点。     

超细改性重质碳酸钙制备及在PVC塑料制品中的应用

作者对超细改性重质碳酸钙填料在ＰＶＣ硬质塑料制品中的应用进行了试验研究，在清华大学工程力学研制的干式超细研磨粉碎机上完成了重质碳酸钙的超细粉碎和改性料的制备，将这种填料添加到超主同分子量ＰＶＣ中制成标准试样。     

干法介质研磨方式超细粉全加工系统的研究

超细化处理是工业原料深加工过程中的重要工序,解决处理量超细粉碎系统的工艺设计问题是非金属矿物加工行业迫在眉睫的任务,通过分析介绍研磨方式的球磨机,振动磨和干法搅拌磨与超细分级机工作原理的特点,确定由它们缚成闭路超细粉经验,介绍了这和睦眼细粉碎系统的可靠性,结合作者多年的工作实践经验,介绍了这咱超细粉碎系统用于重质碳酸钙超细加工的工艺参数选定和特点。     

水介质中碳酸钙颗粒的表面机械力活化改性

以硬脂酸钠为改性剂,研究了在实验室搅拌磨中湿法超细研磨碳酸钙颗粒的表面改性,研究证明,湿法超细研磨过程中的机械力化学效应有利于颗粒表面改性,且改性效果受研磨细度、料浆密度、pH值、料浆温度以及研磨力的影响。在这些影响因素中研磨力是很重要的,应将其控制在适当的范围内。     

白云石的湿法超细粉碎工艺研究

为对白云石进行超细粉碎,利用介质搅拌磨对白云石的湿法超细粉碎工艺进行优化研究。通过对白云石湿法超细粉碎过程中主要工艺参数的优化研究,确定白云石湿法超细粉碎最佳工艺参数。结果表明:当助磨剂为聚丙烯酸钠,用量为白云石质量的0.5%,料浆中物料的质量分数为60%,球料质量比为5∶1,累积研磨时间为3~4h,转速为1200r/min,在此工艺条件下研磨4h后,其d50=0.70μm,d97=1.97μm。     

金红石型钛白粉的湿法超细研磨实验研究

以卧式砂磨机为超细研磨设备,研究研磨介质填充率、磨机转速、矿浆中粉体含量、助磨剂添加量、研磨时间对金红石型钛白粉超细研磨效果的影响。结果表明,在介质填充率为70%,磨机转速为2 250 r/min,矿浆中粉体质量分数为50%,添加助磨剂质量分数为0.4%的条件下,金红石型钛白粉超细研磨20 min制得钛白粉的粒径d50、d97分别可达0.48、1.07μm。     

欧版磨粉机在重质碳酸钙生产中的应用

根据国内重质碳酸钙的生产、应用、加工工艺及粉磨设备的基本情况,着重介绍欧版磨粉机生产重质碳酸钙的干法制粉工艺。结果表明,欧版磨粉机是一种高效节能型技术装备,单机生产能力大,单位能耗低,产品粒度分布窄,产品一次粒度d97=33～200μm,易于实现重质碳酸钙的规模化生产。     

电石渣制备纳米碳酸钙时预处理方式对产品的影响

以电石渣为原料,采用联钙法制备纳米碳酸钙,具体考察了氯化铵铵化和盐酸氨水铵化两种预处理方式对产品的影响,结果表明,电石渣分别经过氯化铵铵化和盐酸氨水铵化预处理后,碳化均能制备出符合国家标准的纳米碳酸钙。氯化铵预处理时,氯化铵与电石渣最佳质量比为1.5：1。盐酸氨水铵化预处理最佳条件为盐酸调节电石渣溶液pH值至8,氨水与电石渣最佳质量比为2：1（以28%氨水计）。电石渣分别在两种预处理方式最佳条件下处理碳化制备纳米碳酸钙的收率、纯度和白度差异较小。氯化铵氨化预处理电石渣处理制备纳米碳酸钙更经济实用。     

矿物湿法超细磨矿中助磨剂的作用效应及其程度的研究

通过考察硬脂酸钠对重质碳酸钙－水矿浆粘度的影响和因硬脂酸钠在重钙表面吸附而导致的颗粒表面自由能的变化以及由此产生的对湿式搅拌磨细磨重质碳酸钙磨矿效果的影响,研究了助磨剂的各种作用效应及其程度。结果表明,助磨剂对矿物湿法细磨的助磨作用是改善矿浆流变性和吸附降低颗粒表面自由能两种效应综合的结果,其中前一作用较强。     

MECHANO-ACTIVATED SURFACE MODIFICATION OF CALCIUM CARBONATE PARTICLES IN AQUEOUS MEDIUM

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沉淀碳酸钙(PCC)的发展及应用

简述碳酸钙的分类、用途、工业现状、国内外在碳酸钙多相合成体系流变学及转递行为、碳酸钙形成机理和形态控制技术以及结晶生长成核理论的研究成果 ,并讨论了碳酸钙粉末表面处理的方法、机理。对高档卷烟纸专用碳酸钙的性能要求进行了探讨     

3D spatial distribution of the calcium carbonate caused by carbonation of cement paste

Carbonation of cement-based materials is one area of concern for the durability of concrete structures. The calcium carbonate caused by carbonation is an important indicator of carbonation degrees. The present paper, using 3D tomography data, proposes a nondestructive method to characterize the 3D spatial distributions of calcium carbonate. It allows monitoring of 3D carbonation evolutions. The evolution of the calcium carbonate distributions in a specimen of cement paste with different carbonation degrees is given using the current method. The results are compared with the average quantity of calcium carbonate determined by thermal analysis. From the sharp edge of the calcium carbonate distribution, we conclude that the accelerated carbonation in this experimental condition is a diffusion controlling process.     

Production of Submicron Particles by Mechanical Treatment: Width of Particle Size Distribution and Fineness of Product

Calcium carbonate (CaCO₃) powders commonly used as a functional filler in paints, inks, papers, plastics, cosmetics, and so on, are generally produced by mechanical treatment (milling). This research was aimed to produce calcium carbonate submicron particles by stirred milling in wet conditions. The experiments were carried out by a batch operation, and determined the change in particle size distribution (PSD) of calcium carbonate. The product size (fineness) and PSD were used in the evaluation of the test results. The results showed that wet grinding in a stirred bead mill using the smaller grinding media (500 µm) is an effective method for reduction of product size (～500 nm) of the CaCO₃ powder.     

Jet mill grinding of portland cement,limestone, and fly ash: Impact on particle size,hydration rate,and strength

While the majority of commercial ordinary portland cement (OPC) is ground using a ball mill or a vertical roller mill, other industries have shown that jet mill grinding can be an alternative approach for grinding materials. This paper investigates the potential application of jet mill grinding for two systems. The first system is a blend of OPC and 15% limestone, and the second system is a blend of OPC and 40% fly ash. It was observed that when jet mill grinding is used, the average particle size of the powders is decreased to approximately 4 μm or less with a narrower particle size distribution than that achieved using ball milling. In addition to evaluating the size and shape of the particles obtained from the jet mill grinding process, this paper focuses on evaluating, using isothermal calorimetry, the effect these changes in particle size and distribution have on the extent and rate of hydration as well as their effect on the compressive strength of cement pastes or mortars.This study also investigated differences between inter-grinding and blending separately ground materials to form an OPC/limestone mixture. Both inter-ground and separately ground OPC/limestone mortars demonstrated an accelerated hydration at early ages accompanied by an increase in early age strength. This appears to be primarily due to the increased surface area of the finer particles that provides more available surface for the hydration reaction. The inter-grinding appeared to be more effective than grinding the materials separately because an improved graded particle size distribution was obtained. The inter-ground OPC/limestone mixture shows accelerated initial hydration at water to powder ratios (w/p, where powder = cement + limestone) of 0.50 and 0.35 when compared with the samples before grinding. At the lower w/p of 0.35, the OPC/limestone mixture appears much more efficient. In the OPC/fly ash mixture, jet mill grinding also accelerates the rate of hydration and strength development.