二氧化硅在真空碳热-氯化法炼铝过程中的行为

Behavior of silica in vacuum metallurgy of aluminum production by carbothermic-chloride process

采用XRD,EDS及热力学分析等方法,对二氧化硅在真空碳热氯化法炼铝过程中的行为进行研究。研究结果表明:碳热还原过程SiO2在较低温度下发生碳热还原反应生成SiC,在更高的温度条件下碳热还原生成低价氧化硅SiO气体;另外还有一定量的SiC与Al4C3结合生成Al4SiC4。碳热还原过程生成的低价氧化硅SiO气体进入低温区歧解得到单质硅与二氧化硅;同时还有氧化铝碳热还原生成的低价氧化铝Al2O气体进入低温区与CO发生二次氧化反应生成氧化铝与碳,低价氧化铝Al2O与低价氧化硅SiO气体在低温区发生反应的可能性较小。碳热氯化过程冷凝产物金属铝的EDS检测分析显示,SiO2碳热还原生成的低价氧化硅SiO歧解产物没有混入最终产物中,从而不会影响金属铝的纯度,该金属铝平均纯度达97.03%。

The behavior of silica in vacuum metallurgy of aluminum production by carbothermic-chloride process was investigated by XRD, EDS and thermodynamic analysis. The results show that SiC is formed at low temperature by SiO2 carbothermic reduction during alumina carbothermic reduction process, SiO（g） is generated at higher temperature which would disproportion into simple substance of silicon and silica at low temperatures, and AlaSiC4 is formed by a certain SiC reacting with A14C3. Reoxidation reaction could occur between A12O（g） and CO, which is generated by alumina carbothermic reduction. However, little possibility of reaction occurs between SiO（g） and A12O（g） at low temperature area. SiO（g） disproportion product didn＇t enter into aluminum metals by EDS analysis for the condensation products during carbothermic-chloride process, which means that final products can not be polluted by it, and the average purity of aluminum metal attains 97.03%.