Separation and purification of ytterbium and iron from nitric acid solutions using N235 extraction

The separation of valuable elements from nitric acid solutions containing ytterbium alloy components was investigated. The extraction and separation efficiency of N235 in a nitric acid system was evaluated by examining the effects of solution acidity, chloride ion concentration, and extractant ratio. The experimental data were analyzed using dynamic calculations. The results indicated that the partition rate of iron increases exponentially with higher chloride ion and hydrochloric acid concentrations, while the partition rate of ytterbium remains unaffected. Iron demonstrated a higher partition ratio in pure hydrochloric acid compared to nitric acid solutions containing ammonium chloride, likely due to the absence of nitrate ions, which inhibits complex formation with N235. The extraction rates of both iron and ytterbium increased with higher trioctylamine concentrations and longer extraction times. Back-extraction experiments revealed that the back-extraction rate of iron gradually decreased with increasing acidity of the back-extraction solution. Emulsification of the organic phase was observed when the acidity was below 0.1 mol/L. Overall, ytterbium and iron were successfully separated through a four-stage extraction process, achieving a ytterbium purity of 99.98%. These findings provide a foundation for the development of ytterbium recovery technologies.