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结合Si-Fe相图,分析了硅铁热还原制镁(皮江法)反应过程中Si-Fe中形态,结果显示:初始含Si量75%的Si-Fe在1200℃基本处于固态,硅铁热还原制镁还原反应主要为固-固反应,反应过程中,物料间的热量及质量传输较困难,反应难于快速、彻底进行。介绍了采用Si-Cu合金还原剂实现固-液还原的Si-Cu热还原制镁新思路、新方法,结合Si-Cu相图,分析了Si-Cu热还原制镁中Si-Cu的形态,结果显示:Si-Cu热还原制镁时,初始含Si量低于35%的Si-Cu在1200℃几乎全过程保持液态,还原反应基本为固-液反应,反应较易快速、彻底进行。采用热力学分析方法,推演出了Si-Cu热还原制镁的主要反应式、吉布斯自由能估算式,临界反应温度估算式,分析了影响吉布斯自由能、临界反应温度及还原反应热力学可行性的因素,结果显示:Si-Cu热还原制镁反应的热力学临界温度随系统气压降低及Si-Cu中Si含量增加而减小;对应于常规真空硅热还原制镁(皮江法)温度(1473 K)和系统气压(13.3 Pa),Si-Cu合金中的Si含量只需高于0.034%,Si-Cu热还原制镁即具备热力学可行性。
Combined with the Si-Fe phase diagram, the morphology of Si-Fe in the ferrosilicon-reduced magnesium (Pidgeon process) reaction was analyzed. The results show that the Si-Fe with initial Si content of 75% Iron reduction reaction of magnesium reduction reaction is mainly solid - solid reaction, the reaction process, the heat transfer between the material and the quality of the more difficult, the reaction is difficult to quickly and thoroughly. A new method and method of Si-Cu thermal reduction of solid-liquid reduction using Si-Cu alloy reducing agent was introduced, and the Si-Cu phase morphology of Si-Cu thermal reduction magnesium The results show that the Si-Cu with initial Si content less than 35% can maintain the liquid state almost at 1200 ℃ during Si-Cu thermal reduction. The reduction reaction is almost solid-liquid reaction, and the reaction proceeds more easily and quickly. . Thermodynamic analysis method was used to deduce the main reaction equation, Gibbs free energy estimation equation and critical reaction temperature estimation formula of Si-Cu thermal reduction magnesium system. The influence of Gibbs free energy, critical reaction temperature and reduction reaction thermodynamics The results show that the critical temperature of thermodynamics of Si-Cu thermal reduction magnesium reaction decreases with the decrease of the system pressure and the increase of Si content in Si-Cu. Corresponding to the conventional magnesium reduction by vacuum silicon reduction (Pijiang method) At temperatures of 1473 K and 13.3 Pa, the Si content of the Si-Cu alloy is only required to be higher than 0.034%. Si-Cu thermally reduced magnesium is thermodynamically feasible.