| 题名 | 由菱镁矿制备无水氯化镁的新工艺研究 |
| 作者 | 欧腾蛟 |
| 学位类别 | 硕士 |
| 答辩日期 | 2007-05-31 |
| 授予单位 | 中国科学院过程工程研究所 |
| 授予地点 | 过程工程研究所 |
| 导师 | 卢旭晨 |
| 关键词 | 煅烧菱镁矿 无水氯化镁 反应结晶 六氨氯化镁 |
| 其他题名 | Study on the new process of producing anhydrous magnesium chloride from magnesite |
| 学位专业 | 化学工程 |
| 中文摘要 | 无水氯化镁电解制备金属镁与皮江法炼镁相比，具有资源利用率高、能耗低、环境污染小等特点，受到了国际上的高度关注。无水氯化镁的制备是电解法生产金属镁的关键环节。本文研究了以菱镁矿为原料，在乙二醇有机介质中反应制备无水氯化镁的新工艺，工艺路线包括：煅烧菱镁矿生成氧化镁；氯化铵在乙二醇溶液选择性浸取氧化镁生成氯化镁；精馏脱去溶液中反应生成的水后，通入氨气与氯化镁反应生成六氨氯化镁沉淀；分离沉淀并洗涤后，煅烧六氨氯化镁得到无水氯化镁。此工艺原料来源丰富，资源利用率高，对环境污染小，具有良好的工业应用前景。 研究发现磨细的菱镁矿在750℃下保温2h左右能使MgCO3完全分解而CaCO3不分解，温度过高时间过长会导致矿粉过烧，影响浸取效率。在浸取过程中，反应物(NH4Cl与MgO)以化学计量比反应、氯化铵的初始浓度为1.23 mol/L时浸取速率最高，浸取过程受表面化学反应控制，表观活化能为44.74 kJ/mol。采用减压精馏方法分离反应中生成的水，保持塔底温度在170℃半小时以内可以达到反应所需的临界水含量。MgCl2•6NH3反应结晶时，氨气的通入速率控制在500mL/min以内，加料速率过快会使晶体不能长大；温度宜控制在10～30℃，温度升高会导致六氨氯化镁结晶反应中出现副反应；反应液中的水含量宜控制在1%以内，在此临界含水量内对产物纯度基本无影响。在恒速升温条件下，MgCl2•6NH3在热分解过程中是分步进行的，50～300℃内分解完全，整个过程需要吸收的热量为124.153kJ/mol MgCl2•6NH3。 |
| 英文摘要 | Producing magnesium metal by electrolyzing anhydrous magnesium chloride, compared with Pidgeon method, has the advantages of high utility of resources, low energy consumption, little pollution to environment. The process of preparing anhydrous magnesium chloride is the key step of electrolytic method for magnesium metal. This article systematically studied the new technology from magnesite to anhydrous magnesium chloride in ethylene glycol. The process includes: calcining magnesite to magnesia, selective leaching calcined magnesite in ethylene glycol dissolved with ammonium chloride, distilling water from leaching solvent, introducing free ammonia into solution to form MgCl2•6NH3 precipitation, thermal decomposing MgCl2•6NH3 to anhydrous MgCl2. High utility of resources, low energy consumption and little pollution to environment make the new technology promising for industrialization. It was found that magnesium carbonate could decompose completely when milled powders of magnesite were preserved at 750℃ for 2 hours. The powders should not be over calcined unless it would affect the leaching reaction rate. During the leaching, the rate reaches the maximum at the stoichiometric proportion of NH4Cl-MgO and with 1.23 mol/L initial concentration of NH4Cl. The process was controlled by surface reaction, of which the apparent activation energy was 44.74 kJ/mol. It took less than 30 minutes to lower down the water lever of solvent by means of vacuum distillation under 170℃. After removing water, the flowrate of ammonia gas should be below 500mL/min in order to make the crystal grow. The temperature could preferably be 10～30℃, higher temperature could possibly make the side reaction happening. The critical water content of solvent should be under 1% of mass percentage, within which it takes no effect on product purity. The decomposition of MgCl2•6NH3 was endothermal and multi-step processes with the enthalpy of 124.153kJ/mol MgCl2•6NH3. |
| 语种 | 中文 |
| 公开日期 | 2013-09-13 |
| 页码 | 78 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.ipe.ac.cn/handle/122111/1154]  |
| 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 | 欧腾蛟. 由菱镁矿制备无水氯化镁的新工艺研究[D]. 过程工程研究所. 中国科学院过程工程研究所. 2007. |
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