Al, ca, and mg are separated from alkali metals in aqueous solution by extraction with an alkylphosphoric acid prewashed with (nh4)2co3. Thus, a 0.5M solution of bis(2-ethylhexyl) phosphoric acid washed with a 1m (nh4)2co3 solution was mixed with 10 pct tributyl phosphate and was used to extract al from pollucite-hcl leach liquor at an organic/aqueous phase ratio of 3:1. The organic layer was scrubbed with dilute hcl at ph 5 and stripped with 5m hcl containing 20 pct hf. The 30 ml of raffinate obtained at ph 6.8 Contained rb 0.12, Cs 7.6, and al 0.0022 G/l, the 50 ml from the scrubbing at ph 4.2 Contained rb 0.01, Cs 0.27, and al 1.7 G/l, and the 75 ml of stripped organic layer contained rb 0.005, Cs 0.005, and al 0.0022 G/l. A similar method was used to separate mg from sea water. Other extraction solvents used were heptadecyl phosphate, mono-di-p- (1,1,3,3-tetramethylbutyl)-phenyl phosphate, and octyl pyrophosphate.
U.S. Pat. 3,514,266; May 26, 1970; Chem. Abstr. 73:27,830Q