A NOVEL MIXER-SETTLER-MIXER THREE CHAMBER INTEGRATED EXTRACTOR FOR THREE-LIQUID-PHASE EXTRACTION OF Li, B and MG FROM SALT-LAKE BRINES

摘要

A novel mixer-settler-mixer three chamber integrated extractor has been proposed for three-liquid-phase continuous extraction and separation of Li, B, and Mg from salt-lake brine. The three-liquid-phase system consists of an organic solvent-rich top phase, tributyl phosphate (TBP) in kerosene, a polyethylene glycol (PEG)-rich middle phase and a (NH_4)_2SO_4-rich aqueous bottom phase. Various influences from liquid flow rate of three phases, stirring speed, salt concentration in brines, aqueous pH values, initial Cl~- concentrations on three-liquid-phase partitioning of Li, B, and Mg were investigated. Experimental results indicate that Li and B can be enriched into top organic phase and middle PEG-rich phase of three-liquid-phase systems, respectively, while most of Mg remains in bottom aqueous phase. The present work highlights a feasible apparatus to perform continuous three-liquid-phase extraction. The results are important for future industrial application of the proposed three-liquid-phase extraction new technique to recover Li and B from high concentrated Mg salt-lake brines in west China.