【作者】 李丽匣；

【导师】 韩跃新； 袁致涛；

【作者基本信息】 东北大学 ， 矿物加工工程， 2005， 硕士

【摘要】 碳酸钙晶须具有成本低、白度高、填充量大的特点，因而大量地用于改善聚合物复合材料的力学性能。为此，碳酸钙晶须的制备引起了人们的高度重视。目前，在国内还未见碳酸钙晶须产业化的报道。 本研究采用Ca（OH）₂浆料中加入MgCl₂作为晶型控制剂的改进碳化法制备碳酸钙晶须。利用高倍生物数码显微镜观察产品的形貌、测量晶须的长度、直径及长径比，利用X—ray衍射检测产品的组成，借助于带有温度自动补偿功能的pH计跟踪反应过程。 影响碳酸钙晶须结晶过程的内部因素包括晶体结构的对称性、结构基元间的作用力、晶格缺陷等，外部因素主要包括反应器的结构因素和操作因素两大类。通过试验，本研究得出了制备碳酸钙晶须适宜的工艺条件：在反应料浆总体积3000ml的条件下，机械搅拌强度238r／min，Ca（OH）₂浓度为0.1M～0.4M，C_Mg²⁺：C_ca²⁺≥0.8，适宜的反应温度为75～85℃，CO₂的充气速度为65～81L／（h·kgCa（OH）₂）。使用分析纯CaO为原料，Ca（OH）₂浓度为0.33M，C_Mg²⁺：C_Ca²⁺=1.2，反应温度T=75℃，二氧化碳充气速度Q_CO2=65L／（h·kgCa（OH）₂），得到了均匀性较强的碳酸钙晶须。晶须长度100～125μm，直径5～7.5μm，长径比近20，含量可达97.3％。分析了各个因素对碳酸钙晶须合成过程的影响。在碳酸钙晶须产品的X—ray图谱中，没有发现氢氧化镁和碳酸镁的衍射峰，说明以MgCl₂为晶型控制剂合成碳酸钙晶须的反应进行得很彻底。 C_Mg²⁺：C（Ca）²⁺的比值、料浆浓度、反应温度等条件的变化会造成系统初始pH值的不同，在不同的初始pH值条件下合成的产品晶型也不一样。分析发生这种情况的原因可能是反应历程不同。 根据碳化反应的热力学和动力学模型，对合成碳酸钙晶须过程中pH值的变化情况进行了分析。研究了晶型控制剂、料浆浓度、CO₂的充气方式和充气速度、反应温度等条件对碳化过程的影响。 本研究成果，对进一步开展碳酸钙晶须制备的研究及扩大试验均具有一定的指导意义。更多还原

【Abstract】 Calcium carbonate whiskers are characteristic of low cost, high whiteness and big package, and they are widely used for improving the mechanic performance of polymer composite. Thus, more and more attentions are put on the synthesis technology of calcium carbonate whiskers. However, there is no report about the industrialization of calcium carbonate whiskers by recently.In the thesis, calcium carbonate whiskers are synthesized via modified carbonization, introducing CO₂ of certain flow rate into suspension of Ca（OH）₂ mixed with MgCl₂ at stated temperature. Motic Digital Microscope DMB is used to observe the appearance and measure the length, diameter and aspect ratio of whiskers, X—ray Diffraction is used to detect the crystalloid structure, and the reaction is examined in the presence of pH meter with temperature compensation.For crystallization process, the internal influence factors are symmetrical characteristic of crystalloid structure, acting force of different basic dollar, and lattice defect, while the external influence factors mainly include reactor structure and operation factors. Based on experiments, the optimum synthesis conditions are achieved as following: in the case of total slurry volume 3000ml, mixing speed 238r/min, Ca（OH）₂ concentration 0.1M-0.4M, ratio of C_Mg²⁺ to C_Ca²⁺ greater than 0.8, reaction temperature suitable 75-85 ℃, CO₂ flow rate 65-81 L/（h·kgCa（OH）₂）. Making use of AR CaO as material, Ca（OH）₂ concentration 0.33M, ratio of C_Mg²⁺ to C_Ca²⁺ 1.2, reaction temperature 75℃, CO₂ flow rate 65L/（h·gCa（OH）₂）, the subject has achieved calcium carbonate whiskers with length of 100¹25μm, diameter of 5⁷.5μm, and aspect ratio of nearly 20, meanwhile, the content of calcium carbonate whiskers in product reached to 97.3%. In addition, the influence of every factor on synthesis process was analyzed. In X—ray atlas of whisker proucts, no diffraction apex about magnesium hydrate or magnesium carbonate was found, which showed the preparation thoroughly reacted.The difference of ratio of C_Mg²⁺ to C_Ca²⁺, suspension density, reaction temperature can更多还原