PURPOSE: To separate an recover high purity Rb in a high yield by adding phosphomolybdic acid to nitric acid-added bittern and dissolving the resulting precipitate in a dil. NaOH soln. followed by neutralization, treatment with an H-type cation exchange resin and elution.

CONSTITUTION: Nitric acid is added to bittern and boiled, and phosphomolybdic acid is added to form a yellow precipitate of Rb3PO4.9MoO3.7H2O. This precipitate is separated by filtration and dissolved in a very small amount of a dil. NaOH soln. The resulting soln. is adjusted to 7pH with hydrochloric acid and fed to an H-type cation exchange resin column to allow Rb to be adsorbed. The Rb is then eluted wit ≤0.5N hydrochloric acid, and this eluate is evaporated to dryness to recover the Rb as rubidium chloride.