Separation of rare earths with solvent impregnated resin. (2nd Report). Separation of Tb, Dy and Ho by Column Method.

Separation of heavier rare earths, Tb, Dy and Ho was investigated by a batch and column method. Solvent impregnated resin can be made by soaking macro porous resin in organo-phosphorous extractant, whose trade name is PC-88 A, diluted in chloroform and removing chloroform from the mixture.It has been revealed from the measurements of pore size distribution and specific surface area of the solvent impregnated resin that extractant is physically adsorbed or holded in macro porous resin. In a batch method the adsorption behavior of Tb, Dy and Ho with the solvent impregnated resin is quite similar to the extraction behavior with solvent extraction. The adsorption behavior for Tb, Dy and Ho, namely the relation of log D vs. pH is very close one another, which suggests the difficulty in the separation of Tb, Dy and Ho by the solvent impregnated resin. In a column method, it is possible to separate and recover lighter rare earth in the adsorption process, and heavier rare earth in the elution process. For instance, in a binary system of Tb and Ho, terbium can be recovered in the yield of 30-70% at 100% purity in the adsorption process, while holumium is collected in the yield of 45-50% at 100% purity in the elution process. From the measurement of the adsorption distribution of Tb and Ho in the column for the binary system, it has been proved that heavier rare earth is substitutionally adsorbed in the column to release lighter rare earth.