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

摘要： 稀土分离过程中常常需要进行稀土与非稀土元素的分离。在硝酸体系中进行了无皂化和皂化P507萃取分离Er³⁺的实验研究。通过作图法确定了无皂化P507萃取Er³⁺的反应式。皂化实验研究发现增加皂化度能够提高Er³⁺的萃取效果，但是皂化度过高会导致反应时水相容易水解而降低萃取率。Er³⁺的萃取率随着初始水相pH的增加而先增加后降低，在初始水相pH为2.0时达到最大值（>95%）。杂质（Ca²⁺、Fe³⁺）的存在对于Er³⁺的萃取率没有影响，铒与钙的分离因子β_{Er³⁺/Ca²⁺}一般都能达到10以上，两者分离效果较好。但是只有在初始水相pH为3.0左右时，铒与铁的分离因子β_{Er³⁺/Fe³⁺}较高（>10）从而两者能有较好的分离效果。

关键词: 稀土, P507, 皂化, 萃取, 分离, 平衡