Cyanex 923从硫酸体系中萃取钪及其与P507和环烷酸的比较

Extraction of Scandium from Sulfuric Solution by Cyanex 923 and the Comparison with P507 and Naphthenic Acid

稀土元素钪(Sc)在相关原料中含量低,伴生杂质元素多,回收困难。针对这一问题,本文系统对比了直链三烷基氧化膦(Cyanex 923)、2-乙基己基磷酸单-2-乙基己基酯(P507)、环烷酸在硫酸体系中对Sc的萃取、分离和反萃。Cyanex 923在高酸度下能完全萃取Sc,而环烷酸和P507则在低酸度下有较高萃取率。Cyanex 923分离Sc与锆(Zr)、钛(Ti)的最佳水相酸度为1 mol/L,分离系数分别为5. 6和10. 6。P507在水相H^+浓度为2 mol/L时对Sc/Zr、Sc/Ti有最大分离系数,分别是21和59. 7。虽然P507有更好的分离效果,但难以反萃。3种萃取剂中仅有Cyanex 923能被有效反萃,在反酸H+浓度为0. 4 mol/L时有最大反萃率。因此,Cyanex 923更适合从含Sc二次资源浸出液中分离回收Sc。

The recovery of scandium（Sc） is difficult due to its low content in resources and large amount of other metals associated with. To solve this problem, the extraction, separation and stripping of Sc by three extractants ：trialkyl phosphine oxides（Cyanex 923）, 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester（P507） and naphthenic acid, were compared in this article. The Cyanex 923 can efficiently extract Sc from a highly acidic solution. The P507 and naphthenic acid have high extraction efficiency of Sc in low acidic solution . The best acidity for the separation between Sc and zirconium（Zr）, Sc and titanium（Ti） by Cyanex 923 is 1 mol/L. The separation ratios of Sc/Zr and Sc/Ti are 5.6 and 10.6, respectively. The largest separation ratios of Sc/Zr and Sc/Ti by P507 are 21 and 59.7, respectively, at an acidity of 2 mol/L. Though the P507 has a higher separation ratio, the loaded Sc on P507 is hard to be stripped by acid. Only the Sc loaded on Cyanex 923 can be efficiently stripped when the acidity of stripping acid is 0.4 mol/L. Taking account of both separation and stripping, the Cyanex 923 is more suitable to separate and recover Sc from the leaching liquor of secondary resources.