Abstract:The residues of salt lake brine from which potassium had been removed were used to extract Rb⁺ and Cs⁺ together with a sulphonated kerosene (SK) solution of 1.0 mol/L 4-tert-butyl-2-(α-methylbenzyl) phenol (t-BAMBP). Rb⁺ and Cs⁺ were enriched and separated effectively by precipitating Mg²⁺ before extraction and by scrubbing out K⁺ and Na⁺ repeatedly before stripping. The effects of the volume ratio of organic phase to aqueous extraction phase (O/A), alkalinity of aqueous phase (c(OH)^-), interference from K⁺ and Mg²⁺, and ratio the volume of organic phase to aqueous scrubbing phase (O/A′) were investigated. The experimental brine was extracted optimally by 5-stage extraction with 1.0 mol/L t-BAMBP in SK, c(OH^-)=1 mol/L, and O/A=1:1. The scrubbing yield of rubidium was only about 10.5% when the extraction solvent was washed 3 times with 1×10^-4 mol/L NaOH at O/A′=1:0.5. After 5-stage countercurrent extraction, the final extraction yields of Rb⁺ and Cs⁺ reached 95.04% and 99.80%, respectively.

Key words: salt lake brine; t-BAMBP; extraction; rubidium ion; cesium ion