Separation of Rare Earth Elements and Scandium by Cation Exchange with Particular Reference to Radiochemical Neutron Activation Analysis of Geochemical Samples

A cation-exchange separation method has been developed for separating the rare earth elements from scandium, using hydrobromic acid as the eluent. Optimum conditions, chosen on the basis of tracer experiments, are: Dowex 50W-X8,200-400 mesh resin, 6.5-7 M HBr, and a flow rate of less than 0.9 cm/min. Under these conditions more thdn 99% of the REE are recovered in the first 12 column volumes of eluent, while leaving all the scandium on the column, and separation factors of 102-103 are readily attainable. This method has been used for radiochemical neutron activation analysis of meteorites, in conjunction with a procedure for determination of 19 sidero-phile or volatile elements. It is faster than the conventional hydroxide-fluoride precipitation, and hence permits a large number of samples to be processed simultaneously.