氨络合法制备无水氯化镁工艺的应用基础研究
文献类型：学位论文
| 作者 | 闫岩 |
| 学位类别 | 博士 |
| 答辩日期 | 2011-06-01 |
| 授予单位 | 中国科学院研究生院 |
| 导师 | 卢旭晨 ; 陈运法 |
| 关键词 | 菱镁矿 水氯镁石 氨络合法 无水氯化镁 六氨氯化镁 |
| 其他题名 | Invesitigation on preparation of anhydrous magnesium chloride by ammonia complexation method |
| 学位专业 | 化学工程 |
| 中文摘要 | 我国是金属镁生产的大国，年产量占全球的80 %以上。但是，我国的金属镁生产几乎全部采用以白云石为原料的皮江法工艺，带来资源利用率低、能耗高、环境污染严重等诸多问题。相比较，电解无水氯化镁工艺是资源利用率高、能耗低、工艺清洁的制镁先进工艺。电解法的关键是制备高纯的无水氯化镁。 本文提出了以菱镁矿或水氯镁石为原料，氨络合法制备无水氯化镁的新工艺，其步骤包括：无水氯化镁乙二醇溶液的制备；无水氯化镁乙二醇溶液中通入氨气，反应结晶制备六氨氯化镁；用氨饱和的无水乙醇溶剂洗涤晶体；热解六氨氯化镁；氨气、乙二醇和乙醇的回收利用。论文对新工艺关键步骤进行了深入研究，取得如下创新性研究结果： （1）系统研究了反应温度、氯化铵乙二醇溶液初始浓度、氧化镁活性、氧化镁平均粒径等因素对氧化镁与氯化铵在乙二醇溶剂中氯化反应的影响，实验优化了氧化镁氯化反应工艺条件。建立了描述活性氧化镁氯化反应的宏观动力学模型，获得了氧化镁与氯化铵在乙二醇溶剂中进行等化学计量比氯化反应的速率方程。 （2）研究了氯化镁乙二醇溶液蒸馏脱水过程。减压蒸馏和常压蒸馏都可以将氯化镁乙二醇溶液中的含水量脱除至0.1 %甚至更低的水平；减压蒸馏效率更高，乙二醇损失率更少。 （3）实验测定了六氨氯化镁在乙二醇溶剂中的结晶热力学规律。采用EDTA化学分析法首次测定了六氨氯化镁晶体在氨饱和的乙二醇溶剂中的溶解度数据及变化规律，六氨氯化镁的结晶热是50.60 kJ/mol。 （4）深入研究了温度、结晶母液浓度、结晶体系含水量、晶种、洗涤剂等因素对六氨氯化镁晶体粒度分布和晶体纯度的影响，实验优化了六氨氯化镁反应结晶工艺。揭示了温度、过饱和度、悬浮密度等变量对结晶成核与晶体生长的影响规律，并在粒数衡算理论基础上，建立了六氨氯化镁反应结晶过程的成核速率方程和晶体线生长速率方程。 （5）差热失重分析法研究了六氨氯化镁热解机理和热解动力学。六氨氯化镁热解脱氨反应分为三个阶段，每个阶段分别脱去六氨氯化镁中的两个氨分子。获得了低温（55~97 ℃）、中温（97~182 ℃）和高温（182~297 ℃）三个阶段下的六氨氯化镁的非等温热解动力学方程。初步进行了太阳热能热解六氨氯化镁技术的研究，提出了进一步研究的方案。 |
| 英文摘要 | China is the largest producer of metal magnesium in the world, and supplies more than 80 % of global demand in recent years. However, magnesium production in China is based on the Pidgeon process, which disadvantages are inefficient magnesium resoure utilization, high energy consumption and serious environment problem. By comparison, the electroanalysis method is a cleaner, efficient and low energy-consumed process. The key step of the electroanalysis method is the preparation of high-purity anhydrous magnesium chloride. The thesis provides a new process, named ammonia complexation method, for producing high-purity anhydrous magnesium chloride from magnesite or bischofite, which comprising steps of preparation of anhydrous magnesium chloride glycol solution, precipitation of magnesium chloride hexammoniate by reaction crystallization between ammonia and magnesium chloride in glycol solution, washing crystals by use of ethanol saturated by ammonia gas, thermal decomposition of the magnesium chloride hexammoniate crystals into magnesium chloride and ammonia, recycling of ammonia gas, glycol and ethanol. The key step of ammonia complexation method have been deeply investigation in this thesis. And creative results are as follows: (1) Effects of temperature, the initial concentration of ammonia chloride, activity and the diameter of magnesia on leaching of magnesia with ammonia chloride in glycol solution have been systemically investigated in this thesis. The process conditions of the leaching also have been optimized. The kinetic model describing this leching of magnesia has been founded. (2) The experimental results of distillation operation of magnesium chloride – glycol solution show that both common and vacuum distillation can remove water to less than 0.1 %. However, the vacuum distillation process is more efficient. (3) The crystallization thermodynamics of magnesium chloride hexammoniate has been determined The solubility data of magnesium chloride hexammoniate in glycol saturated by ammonia gas were determinated by EDTA titration method. The crystallization enthalpy of magnesium chloride hexammoniate is 50.60 kJ/mol. (4) Effects of temperature, concentration of mother liquor, water percentage in solution, crystal seeds and washing solvent on CSD and purity of magnesium chloride hexammoniate have been deeply investigated. The reaction crystallization process has been optimized. The dependent relationship of temperature, supersolubility, suspending density etc. on nucleation and crystal growth has been provided. Baese population balance theory, the equation of nucleation rate and growth rate respectively are obtained. (5) The thermal decomposition mechanism of magnesium chloride hexammonite was studied by TG-DSC. The process of thermal decomposition of magnesium chloride hexammonite can be divided into three steps, and 2 ammonia molecules of one magnesium chloride hexammonite are decomposed during each step. The kinetic equation of three nonisothermal decomposition of magnesium chloride hexammonite are obtained. The thermal decomposition of magnesium chloride hexammonite by use of solar power was researched. The feasible scheme about this project was provied in this thesis. |
| 语种 | 中文 |
| 公开日期 | 2013-09-23 |
| 页码 | 158 |
| 源URL | [http://ir.ipe.ac.cn/handle/122111/1684]  |
| 专题 | 过程工程研究所_研究所（批量导入） |
| 推荐引用方式 GB/T 7714 | 闫岩. 氨络合法制备无水氯化镁工艺的应用基础研究[D]. 中国科学院研究生院. 2011. |
入库方式： OAI收割
来源：过程工程研究所
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