Development of A Novel Production Process of High Purity Niobium for Electron Particle Accelerator

电子粒子加速器材料采用熔盐电解和电子束熔炼相结合的精炼工艺提纯粗Nb。熔盐在Ar气氛下于963K恒流精炼熔盐(26.3质量%LiF-10.5质量%NaF-47.0质量%KF-16.2质量%K_2NbF_7)。经熔盐电精炼和电子束熔炼后，用电感耦合等离子体发射光谱仪测定了纯化铌中金属杂质组分的含量。采用熔盐电精炼的方法可去除粗铌中的难熔金属Ta、W、Mo。尤其是熔盐氟化电解法对粗铌中金属钽的脱除效果显著。电子束熔炼还可以去除氧和氮等非金属杂质成分，粗铌的质量分数为99.8%，纯度为99.99%。

Crude niobium has been purified by a refining process consistiong of molten salt electrolysis and electron beam melting for materials of electron particle accelerator. The molten salt electronrefining was carried out galvanostatically using a FLINAK bath (26.3 mass% Lif-10.5 mass%NaF-47.0 mass%KF-16.2 mass%K_2NbF_7 at 963 K under Ar atmosphere. After the molten salt electronrefining and the electron beam melting, the contents of metallic impurity components in the purified niobium were determined by ICP emission spectrography analysis. Refractory metals such as tantalum, tungsten and molybdenum in crude niobium could be eliminated by means of molten salt electrorefining. Especially, the molten salt electrorefining method using fluoride bath was remarkably effective for the removal of merallic tantalum in crude niobium. Nonmetallic impurity components such as oxygen and nitrogen could be also remove by electron beam melting.Crude niobium of 99.8 mass% purity was found to be to 99.99 mass% by this process.