Isotope enrichment by countercurrent electromigration in molten salts

Sammanfattning: A series of isotope enrichments by electromigration in molten saltslias been carried out during the last, years. The running conditions aresummarized in table 1 and the enrichments achieved are given intables 2—13. Practical details such as the arrangement of the electricalcircuits and the construction of the separation columns are discussed.The number of theoretical plates has been calculated for all samples.A comparison of all the data shows that the length of a theoreticalunit is about twice as great for columns packed with quartz as for thosewith glass, but this length seems to be fairly unaffected by otherparameters, such as grain size of packing or temperature during therun.An attempt to reduce the necessary operating temperature by usingsalt mixtures in the column is described as well as trials of new cathodearrangements which, if suc cessful, could have increased the versatilityof t he enrichment method.There is an obvious systematics in the mass effects for the cationsin halide melts, in fair agreement with the model given by KLEMM.The cation mass effects are much smaller for nitrates than for halides.A review of o ther physical properties of these melts does not show anycorresponding division between nitrates and halides. It is possiblethat the observed divergence has something to do with the factthat the nitrate ion is a polyatomic unit lacking spherical symmetry.The last chapter gives a review of attempts by various methods toenrich isotopes of Li, Mg, Cl, K, Ca, Cu, Zn, Ga, Br, Rb, Sr, Ag, Cd, In,Sn, rare earths, Tl, and Pb. On the whole, electromigration in moltensalts has proved to be a widely applicable method, useful for at leastsome 15 elements.