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采用热力学分析及X射线衍射(XRD)等方法与手段,研究了真空条件下氧化铝碳热还原-氯化法炼铝工艺中冷凝区碳化铝的形成原因。通过热力学研究,在10～100 Pa,温度低于973 K时,Al与C生成Al4C3的反应及Al与CO生成Al4C3与Al2O3的反应满足反应发生的热力学条件。在Al与CO生成Al4C3与CO2的反应中,CO的浓度越小,初始反应温度就越低。实验研究表明,金属铝的碳化主要是由Al与CO反应生成Al4C3与CO2造成,并且CO的浓度分压越小、温度越低,产物中Al4C3越少,产物金属铝的纯度越高。通过改进实验工艺,得到纯度较高的金属铝珠。此研究为提高真空碳热-氯化法炼铝的产率及纯度提供了很好的理论与实验依据。
The formation mechanism of aluminum carbide in the condensation zone in aluminum carburizing - chlorination process under vacuum was studied by means of thermodynamic analysis and X - ray diffraction (XRD). According to the thermodynamic study, the reaction between Al and C to form Al4C3 and the reaction of Al and CO to form Al4C3 and Al2O3 at 10 ~ 100 Pa and below 973 K can meet the thermodynamic conditions of reaction. In the reaction between Al and CO to generate Al4C3 and CO2, the smaller the concentration of CO, the lower the initial reaction temperature. The experimental results show that the carbonization of aluminum is mainly caused by the reaction between Al and CO to form Al4C3 and CO2, and the smaller the partial pressure of CO, the lower the temperature is, the less Al4C3 in the product is and the higher the purity of metal aluminum is. By improving the experimental process, high purity aluminum aluminum beads are obtained. This study provides a good theoretical and experimental basis for improving the yield and purity of aluminum by vacuum carbothermal-chlorination process.