【作者】 余爱萍；

【导师】 徐久军；

【作者基本信息】 大连海事大学 ， 材料加工工程， 2008， 硕士

【摘要】 我国盐湖镁资源十分丰富,但是目前对盐湖盐类资源的不充分开发利用,造成大量镁盐的局部富集,形成了“镁害”。由于高纯氢氧化镁具有广阔的应用前景,本论文以盐湖氯化镁为镁原料,采用氨法连续制各高纯氢氧化镁,从而实现对盐湖镁资源的利用,变“废”为宝。论文首先从热力学、动力学及沉淀理论角度对制备高纯氢氧化镁的工艺路线进行理论分析;然后先后在试验室规模、小试规模上仔细研究了盐湖氯化镁连续制备高纯氢氧化镁这一工艺:最后采用多种检测手段对样品进行全面分析,检测方法涉及激光粒度分析、离子色谱分析、X-射线衍射(XRD)检测分析、扫描电镜(SEM)分析等。首先在试验室规模研究了搅拌速度、反应温度、氨气通入速度等工艺条件对产品粒度和纯度的影响,得到的优化条件为:氯化镁浓度4.17mol/L,搅拌速度300r/min,反应温度45℃～65℃,氨气通入速度300ml/min,陈化时间60min,最后得到平均粒度大于43μm、纯度大于99.9%的高纯氢氧化镁。经小试规模的放大试验证明,当试验规模放大时,优化的试验条件有一定的变化,氯化镁浓度.2.5mol/L,氨气流量45L/min,陈化60min时,试验结果最好;当采用氨水为沉淀剂时,氯化镁浓度3.5mol/L、反应温度65℃、氨镁比2.2:1、搅拌速度500r/min、反应时间60min、陈化温度60℃、陈化时间90min、陈化搅拌速度500r/min时,获得的氢氧化镁Dv50大于39μm,纯度大于99.9%。本论文的研究结果对开发利用盐湖镁资源生产高纯氢氧化镁提供了直接的技术参数。更多还原

【Abstract】 The magnesium resource is very abundant in our country, especially in salt lakes. But at present the inadequate exploitation of the resource from salt lakes, to a certain extend, forms the "magnesium crisis". According to extensive applied prospect of high purity magnesium hydroxide, using magnesium chloride from salt lakes as magnesium material, high purity magnesium hydroxide is synthesized continuously by ammonia. So to extend and improve the development level for magnesium resource from salt lakes comes true, and turns the waste into a valuable product.Firstly it analyzes the synthesis of magnesium hydroxide using precipitation method in theory. Then, there are two stages to study on continuous synthesizing technology of high purity magnesium hydroxide using magnesium chloride from salt lakes, which include laboratory scale stage and pilot stage. Lastly various performances of specimen are tested by Laser particle size analyzer, Ion chromatograph, X-ray diffraction (XRD) and Scanning electron microscope (SEM).In the laboratory scale stage, the technical conditions, such as mixing speed, reaction temperature and inlet speed of ammonia, are considered. The optimum experimental conditions of synthesizing high purity magnesium hydroxide are obtained, which are 4.17 mol/L concentration of magnesium chloride, 300r/min mixing speed, 45℃～65℃reaction temperature, 300ml/min inlet speed of ammonia and 60min aging time. Dv50 of magnesium hydroxide is larger than 43μm, and the purity exceeds 99.9%.In the pilot stage, the amplificatory experiment proves that the optimum conditions would change little, when amplifying the scale of experiment. The best result is obtained on condition that 2.5 mol/L concentration of magnesium chloride, 44L/min ammonia flux and 60min aging time. the optimum conditions of synthesizing high purity magnesium hydroxide by ammonia liquid are 3.5 mol/L concentration of magnesium chloride, 65℃reaction temperature, 2.2:1 relation among mol ratio between ammonia and magnesium, 500r/min mixing speed, 60min reaction time, 60℃aging temperature, 90min aging time and 500r/min mixing speed. In this stage, Dv50 of magnesium hydroxide is larger than 39μm, and the purity exceeds 99.9%.To some extent, the study benefits to the synthesis of high purity magnesium hydroxide by exploiting magnesium resource in salt lakes.更多还原