Na₃AlF₆-LiF体系下Al的水平电解精炼

来源期刊：金属学报2011年第6期

论文作者：贾明 田忠良 赖延清 刘芳洋 李劼 刘业翔

文章页码：727 - 734

关键词：Al； 纯度； 电解质； 电解精炼； 电流效率

Key words：aluminum； purity； electrolyte； electrorefining； current efficiency

摘    要：在纯氟化物电解质体系下,以原Al为阳极,利用杂质与Al析出电位的差别,采用水平电解槽进行了Al的电解精炼提纯研究.结果表明:水平电解槽导致的电流密度分布不均没有对精炼过程造成不利影响,电解过程槽电压平稳;预电解对电解质净化效果明显,预电解后电解质中Cu,Si和P的含量分别降低到3.2×10^-6,14×10^-6和1.5×10^-6.与三层液精炼Al相比,水平精炼阴极Al是沉底的,受上层电解质保护从而减少了烧损,电流效率最高达98.6%.最后得到的精炼Al与原Al相比,Fe,Si,Zn和Cu等杂质的含量明显降低,特别是Cu含量由14.5×10^-6减少到0.9×10^-6,精Al纯度达到99.99%.

Abstract: A creative and simple horizontal electrorefining method had been developed for high pure aluminum production in fluoride molten salt.Impure primary aluminum was purified due to the different electronegativity between Al and impurities during electrorefining.Pre-electrolysis was effective in the purification of electrolyte,concentration of impurities such as Cu,Si and P were reduced to 3.2×10^-6,14×10^-6 and 1.5×l0^-6,respectively.Aluminum electrorefining could run steady with current density as high as 800 mA/cm²,which indicated that the uneven current density distribution had no bad effect on the electrochemical process.The anode and cathode were both covered by Na₃AlF₆-LiF electrolyte,which largely reduced the oxidation of aluminum at high temperature and yielded a high current efficiency of 98.6%.The analysis of the anode feed and refined aluminum showed a remarkable reduction of the mass fraction of Cu,from 14.5×10^-6to 0.9×10^-6.Besides,particular mention should be made of efficient removal of impurities like Fe,Si and Zn,the purity of electrorefined aluminum was above 99.99%.