基于熔融态氯化镁热解实现新镁钛联合的研究

New Mg-Ti Combination Based on the Pyrolysis of Molten Magnesium Chloride

摘要:

现行的Kroll法生产海绵钛存在的问题是镁电解的投资较高，以及氯的环境污染控制要求较高。基于此，本工作提出了将还原蒸馏产生的熔融态氯化镁直接氧化热解得到高纯氧化镁及氯气，氧化镁经热还原法炼镁，实现海绵钛过程新的镁钛联合。本工作对新的镁钛联合关键环节熔融态氯化镁氧化热解过程进行了研究，通过绘制Mg-O-Cl体系优势区图，获得MgO相稳定存在的条件；确定了适宜的反应条件：反应温度1200 ℃、输入氧分压0.1 MPa，反应时间为50 min，该条件下，氯化镁的热解率可达99.9%，产物中氯含量为0.00262%；XRD和SEM分析表明：氧化镁结晶度高，颗粒粒度分布均匀，分散性较好，为不规则的六面体，氧化镁颗粒的平均粒度在1 μm左右。

Abstract:

The current Kroll method used to produce sponge titanium utilizes a process cycle of magnesium metal and chlorine gas via the electrolysis of magnesium chloride. The main issues are the high capital cost of the electrolysis process and the environmental regulations limiting high chloride concentrations. Thus, the authors have developed a conceptual method involving the pyrolysis of magnesium chloride as well as a reduction process which allows for a cycle of magnesium and chloride. The magnesia obtained in this process can be used to prepare magnesium metal through a thermal reduction method. This paper has studied the pyrolysis of magnesium chloride in detail, which is the key part of this new Mg-Ti cycle method. By plotting Mg-O-Cl predominance diagram, the conditions in which MgO stably exists can be found. The experiments show that the optimum reaction conditions are as follows: pyrolysis temperature 1200 oC, pyrolysis oxygen partial pressure 0.1 MPa and pyrolysis time 50 min. The pyrolysis rate of molten MgCl2 can reach 99.99% and the chlorine content in the product is 0.00262% under the optimum conditions. The obtained MgO powder was analyzed by XRD and SEM. These MgO powders, showing an irregular hexahedral shape, have an average diameter of 1 μm with uniform size distribution, good dispersity and high crystallinity and purity.