【作者】 李秋菊；

【导师】 陈银飞； 刘华彦；

【作者基本信息】 浙江工业大学 ， 工业催化， 2007， 硕士

【摘要】 我国镁资源十分丰富，盐湖中各种镁盐储量巨大，菱镁矿储量也占世界之首，利用盐湖（尤其青海盐湖）水中镁盐和菱镁矿石直接生产高附加值氢氧化镁阻燃剂的高等院校和研究机构越来越多，但对于利用工业生产中副产的镁盐废液制备高附加值氢氧化镁阻燃剂的研究却还是空白。本文主要是充分利用化工企业生产过程中产生的镁盐废液，最大限度地降低生产成本和环境损害，制备高附加值的氢氧化镁阻燃剂产品。首先对制备氢氧化镁的各种合成工艺进行分析，权衡利弊，选择两步法工艺制备阻燃型氢氧化镁。即以氯化镁为原料，反向滴加到氨水中制备普通氢氧化镁，然后在200℃反应釜中对普通氢氧化镁进行水热改性。经过大量的实验得出较合适的条件是：加料方式：反向滴加（即氯化镁加入氨水中）镁离子浓度：1.5～2.5mol／L氯化镁加入速度：2.5mL／minC_MgCl2／C_NH3.H2O：1／1反应终点的溶液pH值：10.0反应温度：40℃陈化温度：：40℃陈化时间：60min水热介质：NaOH水热改性时间：4h水热改性温度：200℃通过扫描电镜（SEM），X射线多晶衍射仪（XRD），全自动氮物理吸附仪（BET）和激光粒度仪等对产品进行表征分析，表明制备的氢氧化镁是规则的六方片状，BET＜10m²／g，纯度高于99％，满足其作为阻燃剂的要求。实验还从理论上分析了氢氧化镁的结晶习性，得出其结晶机理。并且简单讨论了不同表面改性剂对样品的表面形貌和分散性的影响，在实验范围内，证实复合表面改性剂（油酸钠和十二烷基硫酸钠）对样品的改性效果较好。此外，把利用工业含氯化镁废液和分析纯氯化镁作为原料分别制备的氢氧化镁产品与工厂提供的氢氧化镁，进行分析比较可知，前两种产品形貌、晶型和表面积相近，而工厂提供的氢氧化镁和前两者相差很大，这说明实验室前期探索获得的工艺条件和规律，可以指导后续的中试研究和工业化生产。更多还原

【Abstract】 Magnesium hydroxide flame-retardant has been a hot focus forresearchers at home and abroad for its characteristics of highdecomposition temperature, heat stability, harmless, no smoke, and etc. InChina, there are abundant magnesium resources such as huge reserves ofmagnesium chloride in salt lakes and magnesite. However, the behindhandtechnology and process blocked the production of high quality magnesiumhydroxide. So more and more colleges and institutes began to grope for thepreparation of high quality magnesium hydroxide flame retardant with theabove two raw materials. But there are no any reports about the preparationof high quality magnesium hydroxide flame retardant using the byproductof magnesium chloride in chemical plant as raw materials.In this paper, we studied the preparation techniques of high qualitymagnesium hydroxide flame retardant using byproduct magnesium chloridein chemical plant as raw materials, which was very economical andenvironmental-friendly. Weighing the advantage and disadvantage of technical processes, the two-step process was chosen which was applied inthe preparation technology, the first step was to obtain common magnesiumhydroxide by titration of magnesium hydroxide （AR） into ammonia, thesecond step was to modify magnesium hydroxide by hydrothermal methodat 200℃in special autoclave.The better reaction conditions were concluded as follow by plentifulexperiments.Titration order: magnesium chloride adding into ammoniaConcentration of magnesium chloride: 1.5～2.5mol/LVelocity of titration: 2.5mL/minC_MgCl2/C_NH3.H2O: 1/1pH at ending of reaction: 10.0Temperature of precipitation: 40℃Temperature of post-precipitation: 40℃Time of post-precipitation: 60minHydrothermal time: 4 hHydrothermal temperature: 200℃The samples were characterized by XRD, SEM and BET, the resultsshowed that the samples with above 99％purity and below 10m²/g BETwere regular hexa-plate, and the quality of samples could satisfy thedemand of flame retardants. After analyzing the crystallizationcharacteristics of nanometer magnesium hydroxide and its crystallization mechanism, we confirmed that it was necessary to control nucleation andgrowth velocity in order to achieve the high dispersive products. Thefunction of surface modifiers was also discussed, which proved thatcomposite surface modifier-sodium oleate and sodium dodecyl sulfate wasbetter than single one.In contrast to magnesium hydroxide provided by chemical plants, thetwo products which were prepared respectively by the magnesiumchloride（AR） and the byproducts of magnesium chloride produced bychemical plants had been turned out to be similar resultsin the morphology,size and BET, which indicated that the conditions and rules of preparationobtained from our research could be useful in the coming industrialproduction.更多还原