【作者】 王少青；

【导师】 刘进荣； 李彩虹；

【作者基本信息】 内蒙古工业大学 ， 化学工艺， 2007， 硕士

【摘要】 本文以吉兰泰盐湖卤水综合利用为背景,研究盐湖卤水除杂并副产超细氢氧化镁工艺,为吉兰泰碱厂30万吨/年纯碱装置提供合格卤水,提高盐湖卤水的利用效益。本文的第一部分研究工作是探索吉兰泰盐湖卤水除杂工艺,基于除杂效益与成本的考虑,比较了石灰—纯碱法、烧碱—纯碱法和氨—纯碱法等不同除杂方法,采用石灰—纯碱法去除盐湖卤水中的杂质。通过单因素实验,考察了体系温度、沉淀时间、搅拌速率、石灰乳浓度等因素对去除盐湖卤水中杂质的影响。研究结果表明,采用石灰—纯碱法去除盐湖卤水中杂质的适宜条件为,反应时间为25min,镁离子与石灰乳物质量的配比为1:1.1,石灰乳的浓度为2～3mol·L^-1,体系温度为60℃,搅拌速率为60～70r·min^-1,氢氧化镁晶种用量为350g·m^-3卤水,聚丙烯酰胺絮凝剂用量为120g·m^-3卤水。除杂后卤水杂质含量符合纯碱生产对原料的要求,采取该工艺能有效改善沉淀物的沉降性能。第二部分研究内容是探索利用卤水除杂得到的沉淀物,制备超细氢氧化镁的工艺。首先探索卤水除杂得到的沉淀物酸化及酸浸液净化的条件。酸化适宜工艺条件为,采用盐酸酸化的反应温度为20℃～25℃,反应压力为常压,反应时间40min,控制酸浸液pH为7.0～7.5;酸浸滤液的净化条件为,以硫酸镁为净化试剂,净化温度为20℃～25℃,净化时间为30min,硫酸镁与酸浸液中钙离子配比为1.1:1.0,乙醇加入量为5ml（以30ml酸浸液为基准）。结果表明,酸浸液中的钙离子去除率为95.26%。以净化后的酸浸液和氨水为原料,加入适量的PEG2000作为分散剂,利用直接沉淀法制备超细氢氧化镁粉体。通过单因素实验,考察了体系温度、沉淀时间、搅拌速率和氨水浓度等因素对氢氧化镁颗粒平均粒径的影响。利用透射电子显微镜、X射线粉末衍射仪、红外光谱和粒度分析仪对制备的氢氧化镁样品进行了分析和表征。结果表明,采用以确定工艺条件制备的氢氧化镁质量达到HG/T3607—2000标准要求,平均粒径为89.5nm,呈薄片状,分散性较好,粒子为六方晶系结构。更多还原

【Abstract】 Taking the comprehensive utilization of brine from Jilantai Salt Lake as the background, a process was experimentally studied on removing impurities from brine of Jilantai Salt Lake and preparing ultrafine magnesium hydroxide powder as a byproduct in order to provide qualified brine for 30000 tons/year of soda unit, and to increase the utilizable benefit of the brine. The first part in the present work is to explore the process for removing impuritiesfrom Jilantai Salt Lake. On the basis of production cost and benefit for removal of impurities, different methods of removal of impurities were compared, including lime-soda, sodium hydroxide-soda, ammonia-soda method, and lime-soda method was taken as the method of removing impurities method. Effects of system temperature, precipitation time, agitation speed and concentrations of lime slurry on the removal magnesium from brine were examined and suitable range of every techniques condition were obtained by means of single-factor test. The results show that the appropriate conditions for the removal of impurities are as follows: reactant time, 25 min; molar ratio of magnesium ions to lime slurry ,1:1.1; concentration of lime slurry ,2～3mol·L^-1; reactant temperature, 60℃; agitation speed ,60～70 rpm; the quantity of magnesium hydroxide seed added, 350g·m^-3 brine; quantity of PAM 120g·m^-3 brine, respectively. The content of impurities in the purified brine meets the requirement for producing soda. Sedimentation result of magnesium hydroxide is improved when process conditions above mentioned were adopted.In the second part, the exploration was made on the process of preparing ultrafine magnesium hydroxide with precipitate as raw material, in which precipitate was obtained by disposal of impurities from brine. Firstly, the acidification and purification conditions of the precipitate were determined. The acidification conditions are as follows: reaction temperature, 20℃～25℃; reaction time ,40 min; and pH of the hydrochloric acid leaching solution , 7.0～7.5. The purification conditions are in the following: reaction temperature ,20℃～25℃; reaction time,30 min; molar ratio of calcium ions to magnesium sulfate ,1:1.1; the quantity of ethanol , 5ml.The results indicate that the removal yield of calcium ions using hydrochloric acid leaching liquor was 95.26%. The preparation of ultrafine magnesium hydroxide powders was conducted by chemical precipitation method with hydrochloric acid leaching solution purified and ammonia as raw materials, and suitable amount of PEG2000 as dispersant. Influence of system temperature, precipitation time, agitation speed and concentration of ammonia on the mean particle size of magnesium hydroxide particles were studied The samples obtained from the proper conditions were characterized by X-ray diffraction（XRD） , transmission electron microscopy （TEM）, infrared absorption spectrometry （IR） and the particle size distribution analyzer. The results show that the mean particle size of magnesium hydroxide is 89.5nm, with flake shape, fine dispersion, hexagonal crystalloid configuration The sample specifications coincide with the standard stipulated in HG/T3607-2000.更多还原