关键词: 稀土, P507, 皂化, 萃取, 分离, 平衡

Abstract: It is a common practice in rare earth element separation for separating rare earth metals with non-rare earth elements. In this paper, solvent extraction experiments of Er³⁺ with P507 and saponified P507 in nitric acid solution and its separation from Ca²⁺ and Fe³⁺ were performed. The extraction reaction of Er³⁺ with P507 was determined by graphical method. It was found that increasing saponification degree improved extractability of Er³⁺. But high degree of saponification led to the decrease of extractability due to Er³⁺ hydrolysis in aqueous phase. The extractability of Er³⁺ increased with the increase of initial pH in aqueous phase. When initial pH in aqueous phase was around 2.0, extractability of Er³⁺ reached a maximum (>95%). The impurities (Ca²⁺, Fe³⁺) barely influenced the extractability of Er³⁺ at the present concentration range. Separation factor of β_{Er³⁺/Ca²⁺} was higher than 10, which indicated that Ca²⁺ could be effectively removed from Er³⁺. When initial pH in aqueous phase was around 3.0, separation factor of β_{Er³⁺/ Fe³⁺} was higher than 10 which showed a good separation of Fe³⁺ from Er³⁺.

Key words: rare earth, P507, saponification, extraction, separation, equilibrium