Investigations on the solvent extraction from molten salts by tracer technique

The distribution of terbium in a three-phase system of an organic extractant, a fused salt and metallic gallium, as well as in the corresponding two-phase subsystems has been studied. Changing the concentrations in the organic and ionic phases the distr;bution ratios can favourably be veried and so the selectivity of extraction improved. The lithium nitrate -ammonium nitrate eutectic (melting at 366 K) was used as the ionic phase and gallium, the only multivalent metal beside mercury forming a liquid at moderate temperature represented the metallic one. Tri-n-butyl phosphate thenoyl-trifluoroacetone and dimethyl sulphoxide at various concentrations diluted with decaline were used as solvent extractants while terbium was chosen as the representative of the lanthanide group, in the form of 160Tb tracer of high specific activity, enabling to keep solute concentrations as low as 10-6M. The equilibrium measurements were performed at 383 K by shaking sealed glass ampoules containing the three immiscible phases and the solute in a thermostat for one hour. The distribution ratios were calculated by determining the concentration of the solute in aliquots of the samples radiometrically. (T.G.)