RECOVERY AND SEPARATION OF LANTHANUM(III), ALUMINUM(III), COBALT(II),AND NICKEL(II) FROM MISCH METAL BY SOLVENT-EXTRACTION USING BIS(2-ETHYLHEXYL)PHOSPHINIC ACID

This paper describes use of bis(2-ethylhexyl)phosphinic acid as a reag ent for extraction and mutual separation of lanthanum(III), aluminum(I II), cobalt(II), and nickel(II) in 1.0 mol/L sodium nitrate. The extra ction and stripping behavior of the four metal ions has been investiga ted using the extractant in Solvesso #150 as a diluent. The mutual sep aration and recovery of the metal ions from their mixtures has been te sted by multistage extraction with a conventional separator funnel. A set of separation schemes has also been proposed for a continuous coun tercurrent multistage extraction which is comprised of ten extraction stages, four scrubbing stages, and seven stripping stages. Lanthanum(I II) and aluminum(III) are coextracted but separated by selective strip ping into different concentrations of hydrochloric acid. Cobalt(II) ca n be extracted with the nickel(II)-preloaded extractant solution, wher eas nickel(II) remains in the aqueous phase. The successful separation of these metal ions from a misch metal-simulated sample is presented.