Investigation of thorium separation extraction process from rare earths sum by different extragents

Thorium extraction has been studied with a salt of quaternary ammonium base (QAB), petroleum sulfoxides (PSO), and their mixtures with TBP. Extraction has been conducted at a ratio between organic and aqueous phases 1:1. During extraction with trialkylbenzylammonium nitrate (TABA) and TBP thorium concentration in the organic phase grows with an increasing HNO3 concentration in an aqueous phase (for TBP maximum value is observed when acidity is about 1.5 M/l). With respect to extraction ability, TABA nitrate exceeds considerably TBP. The values of thorium concentration in an organic phase close to limiting are attained at small concentrations of TABA nitrate (5-10%) and low acidity of aqueous phase. Because of extremely small distribution coefficients of thorium in the process of extraction with TBP, thorium distribution has been determined in the presence of a salting-out agent (5 N NH4NO3). It has been shown that upon thorium extraction with a mixture of PSO and TBP, distribution coefficients are higher than the total coefficients upon extraction with individual extragents of the same concentration, i.e. the sinergetic effect takes place. Thus, for extractive separation of thorium from REE use can be made of RSO, TABA, and their mixtures with TBP