Uranium(VI) forms strong anionic complexes of the type [UO2(S04)2] -~ and EU0~-(S04)3]-4 in sulphurie acid solutions; the formation constants for these complexes are 350 and 2500 respectively 1. The anionic carbonate complex EU02(C03)8] -4 is much stronger, hence many ion exchange separations of uranium from commonly associated cations are possible. PREUSS AND I~UNIN 1, and GRINSTEAD et al.2 recovered uranium from carbonate and sulphate leach systems. BANERJEE AND HEYN 8 separated uranium from bismuth by anion exchange in sulphuric acid solution, at pH I.O -1.5. Using essentially the same principle, SusIr worked out separation methods of uranium from cerium, alkali metals, and a few divalent metals. MURTHY ~ employed a carbonate medium for the anion-exchange separation of uranium from vanadium; vanadate was adsorbed along with the uranium complex, but was removed by elution with sodium carbonate solution and finally uranium was eluted with sodium chloride solution. Uranium(VI) also forms anionic chloro-and nitrato-complexes6,L which permits anion exchange separations of uranium from vanadium, iron etc.
However, systematic anion-exchange studies of uranium are lacking. The present paper describes the anion exchange behaviour of uranium(VI) in sulphate and carbonate systems, which are the two principal leach liquors of uranium. The strongly basic, quaternary ammonium type anion exchanger, Dowex 2IK, was employed. Hydrochloric, nitric, sulphuric and perchloric acids and sodium chloride, ammonium chloride, sodium nitrate and sodium sulphate were studied as eluting agents. Uranium was separated from the important fission product elements e.g., cerium, zirconium, caesium, silver and cadmium, from vanadium and also from phosphate and molybdate.
APPARATUS AND REAGENTS
Apparatus
Ion-exchange column and Cambridge pH meter. The ion-exchange column was similar to that previously describedS; a resin bed, i. 4 )< 14. 5 cm, was used.
Reagents
The chemicals used were of reagent grade, unless otherwise specified. A uranium solution was prepared from uranyl nitrate hexahydrate (Mallinckrodt A.R.) and standardized by the usual oxine method. For ion-exchange runs, ca. 25 mg of uranium was taken.