Extraction of yttrium using naphthenic acid with different acid numbers

Abstract

Naphthenic acid with acid number of 100–200 mg KOH/g could be used to extract yttrium in the system of 20% naphthenic acid + 20% n-butanol + 60% n-hexane. A transparent and uniform phase was formed during saponification but did not influence the extraction process. n-Butanol and n-hexane could shorten phase separation time and lessen emulsification. Excess naphthenic acid and ammonia, and non-naphthenic acid substances contributed to emulsification and difficulty in phase separation, which were especially serious in system of 20% naphthenic acid + 20% 2-octanol + 60% kerosene. Naphthenic acid with acid number <100 mg KOH/g was unsuitable for extraction in either system. Extraction percentages were 99% and 46% when being saponified by 12.7 and 6.3 mol/L ammonia, respectively.