焦炭真空还原氧化镁的热力学分析及实验研究

Thermodynamic analysis and experimental study of the thermal reduction of magnesia by cokes in vacuum

在真空条件下使用焦炭还原氧化镁制取金属镁是低能耗的镁冶金方法。本文计算了氧化镁与碳之间可能发生的三个还原反应的吉布斯自由能与温度的关系,确定了压力为20Pa时,在室温至2000K的温度范围内,只有MgO(s)+C(s)=Mg(g)+CO(g)可以发生,反应起始温度为1387K。在热力学分析基础上,使用焦炭作为还原剂在真空条件下还原氧化镁制备金属镁。研究了反应温度对氧化镁还原率的影响。反应产物为结晶良好,纯度为99.94%的粗镁。

Thermal reduction of magnesia by cokes under vacuum condition is a low energy consuming method for magnesium metallurgy. The Gibbs free energies for the possible chemical reaction between magnesia and carbon were calculated as a function of temperature and pressure. It was confirmed that only reaction MgO（s） ＋ C（s） = Mg（g） ＋ CO（g） can occur when the temperature is below 2000K under 20Pa vacuum. Based on the thermodynamic analysis, the magnesia was thermally reduced using the cokes as the reducing agent. The effects on reduction temperature on the reduction ratio of magnesia were investigated. The condensed magnesia is well - erystallizated with the purity of 99.94%.