Solvent extraction of rubidium and cesium from salt lake brine with t-BAMBP-kerosene solution

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-(alpha-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 1x10-4 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.