高纯氢氧化镁的合成

发布时间：2018-03-20 03:13

本文选题：轻烧粉　切入点：酸浸　出处：《沈阳工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：氢氧化镁是现代工业中十分重要的化工原料和添加剂，它具有阻燃、抑烟、填充等功能，并且无毒、无害、无腐蚀性，极具发展潜力，具有较高的经济和社会价值，近年来成为研究热点。本文针对辽宁省丰富的轻烧粉资源现状，氢氧化镁的市场潜力，及生产中存在的主要问题，以轻烧粉为原料，酸浸除杂后得精制硫酸镁溶液，与氨水反应合成氢氧化镁，再经水热改性，最终得到高纯氢氧化镁。通过实验得到了轻烧粉酸浸的最佳条件：在常压下，硫酸浓度（质量浓度）10.0%，硫酸与硫酸铵比7:3，复配酸镁比1.4:1，反应温度75℃，反应时间40min，搅拌强度450r·min-1，浸取率可达96.29%。通过X射线衍射（XRD）检测，煅烧后的样品为硫酸镁。依据不同金属离子水解时pH值的差别，在提纯粗硫酸镁溶液时，，用氨水严格控制pH值为6，60℃恒温水浴，除去铁、铝等杂质，再调节pH值为8.5左右，加热至沸过滤，精制后的硫酸镁溶液经蒸发、结晶、煅烧后，纯度达到99.93%以上。通过实验研究了精制硫酸镁溶液浓度、反应温度、氨水用量、搅拌速度对氢氧化镁收率的影响，确定了合成氢氧化镁的最佳实验条件：硫酸镁浓度为1.5mol·L-1，反应温度50℃，反应时间为50min，氨镁比为3:1，转数为450r·min-1。所得产品为卡房状氢氧化镁聚集体，表观平均粒径为24.55μm，纯度达99.9%以上，收率为90.16%。研究了阴离子型、阳离子型、非离子型和复配型多种类型添加剂对氢氧化镁的影响，均没有改变氢氧化镁的晶形和形貌，但是会引起晶体的极性和结晶度的变化，可能是因为硫酸镁中的反离子起了主要作用。通过实验研究了水热改性对最佳条件下合成的氢氧化镁晶形和形貌的影响，确定了氢氧化镁水热改性的最佳条件：水热时间为12h，水热温度为220℃，氢氧化钠浓度6.0mol·L-1。所得样品极性小，形貌规则，分散性良好，结晶度高，热稳定性好，表观平均粒径为2.16μm，纯度达99.94%以上，收率为88.13%。
[Abstract]:Magnesium hydroxide is very important in modern industry, chemical raw materials and additives, it has flame retardant and smoke suppression, filling and other functions, and is non-toxic, harmless, non corrosive, has great potential for development, with high economic and social value, in recent years become the focus of research. Based on Liaoning province abundant light burning powder resources 2 market potential, and the existing problems in the production, with the light burning powder as raw material, acid leaching solution was prepared after Magnesium Sulfate, and synthesis of magnesium hydroxide by reaction of ammonia, hydrothermal modification, finally obtained the Gao Chunqing Magnesium Oxide.
The optimum conditions of the light burning powder obtained by acid leaching experiment: under normal pressure, concentration of sulfuric acid (concentration 10%), sulfuric acid and ammonium sulfate than 7:3, mixed acid magnesium ratio 1.4:1, reaction temperature 75 C, reaction time 40min, stirring intensity of 450R - min-1, the leaching rate can reach 96.29%. by X ray diffraction (XRD) detection, calcined samples for Magnesium Sulfate.
On the basis of the hydrolysis of different metal ions when the pH value of the difference in the purification of crude Magnesium Sulfate with ammonia solution, strictly control the pH value of the 6,60 constant temperature water bath, the removal of iron, aluminum and other impurities, and then adjust the pH value is about 8.5, heated to boiling filtered, Magnesium Sulfate solution after purification by evaporation, crystallization and calcination. The purity of more than 99.93%.
Through the experimental study on the purification of Magnesium Sulfate solution concentration, reaction temperature, ammonia dosage, stirring speed on the yield of magnesium hydroxide, the optimum experimental conditions for synthesis of magnesium hydroxide: Magnesium Sulfate was 1.5mol - L-1, the reaction temperature is 50 DEG C, the reaction time is 50min, ammonia and magnesium ratio is 3:1, the speed was 450R the product is min-1. card the magnesium hydroxide aggregates, the apparent average particle size of 24.55 m, reached a purity of more than 99.9%, the yield of anionic 90.16%., cationic, nonionic and compound effects of various types of additives on the magnesium hydroxide, did not change the crystal shape and morphology of magnesium hydroxide, but will cause changes in polarity and crystal the degree, probably because the counter ion of Magnesium Sulfate has played a major role.
Through the experimental study on the effect of hydrothermal modification of magnesium hydroxide crystal and morphology of synthesized under the optimum conditions, the optimum conditions of magnesium hydroxide hydrothermal modification of hydrothermal time 12h, hydrothermal temperature is 220 DEG C, the concentration of sodium hydroxide 6.0mol L-1. samples from polar small, regular shape, good dispersion, crystallization high degree of thermal stability, apparent average particle size of 2.16 m, reached a purity of more than 99.94%, the yield was 88.13%.

【学位授予单位】：沈阳工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ132.2

【参考文献】