Linear alkylbenzene (LAB) as diluent for extractants. Extraction of rare-earth elements with solutions of neutral organophosphorus compounds in LAB

Abstract

Extraction of REE with solutions of neutral organophosphorus compounds (TBP, TIAP, DIOMP) in a new diluent, linear alkylbenzene (LAB), was studied. LAB exhibits significant advantages over known diluents: high flash point (+147°C), nontoxicity, absence of odor, low cost, availability, and good compatibility with polymeric structural materials. LAB is well compatible with TBP, TIAP, and DIOMP. Extraction of HNO3 and REE nitrates is not accompanied by precipitation of extractable complexes or by formation of a second organic phase in a wide concentration range, up to saturation of the extractant. The major extractable complex in extraction of REE nitrates is Ln(NO3)3·3NOPC, where NOPC = TBP, TIAP. The main parameters of extraction systems (distribution ratios, separation factors) with LAB are similar to those of the related systems with paraffin hydrocarbons as diluents. Experiments on group separation of REEs on a 56-step extraction installation gave results agreeing with the calculation data.