PREPARATION OF PURE U30. FROM CRUDE DIURANATE BY INTERIV[EDIATE COMPLEX FORMATION BY N. S. KaUSm'~hVR~hD ~ V. V. DADAPE (Atomic Energy Establishment, Bombay, India)

Rr November 16, 1956 (Communicated by Dr. H. J. Bhabha, v.R.s., v.^.sc.)

SEV~~aATION of from va¡ undesirable elements is usually done by solvent extractiorfl '2 and several other complexing proeedures. ~4 Bolton5 and Baker e have reported the formation of soluble complexes of the type M3UO~.F5 (M = K, NH4, whŸ are oxŸ by hydrogen peroxide in aqueous solutions to insoluble per-eompounds 7 of the type M4U40~Fe.xH~O. Preliminary studies have been made for the sep of uranium from , rare e and iron, making use of the above complexes, and the results given below. Nitrate solutions of uranium, thorium, r earths and iron were mixed together and potassium fluoride (of ammonium fluo¡ was added slightly in excess of that required for complexing the above elements. Fluo¡ of tho¡ and rare earths got precipitated while those of uranium and iron remained in solution in the forra of soluble complexes. The precipitate was washed with water to recover aU uranium. Conditions of pH require to prevent precipitation of uranium together with thorium and rare earths fluo¡ were studied and the results given in Table I. The solution after the removal of tho¡ and rare earths was treated with enough hyrogen peroxide to precipitate the per (the composition of which is to be established) of the uranium complex M,UO,Fs. The in- fluence of pH on the complete precipitation of uranium free from iron was investigated and the results given in Table II. The effeet of change in eoneentrations of thorium, r earths and iron on the separation of uranium was also studied and the results given in Table ]:II. Employing the above proeedure, crude sodium diuranate (50 g.) contain- ing ThO, 0-4%; Pare earth oxides 1.7%; FeO3 0-6%; SiO., 0-62%; and UaOs 78.2% was converted to uranium oxide whieh on analysis gave the

20 Preparation of Pure Ua08 from Crude Sodium Diuranate 21

TABLE I Effect of pH on the separation of uranium from thorium and rare earths

pH of Oxides of Oxides pH filtrate U30 s thorium Ua08 ThO~ of rare pH adjusted after re- in the and rare mg. mg. earths initial before KF moral of filtrate earths in mg. addition insolu- mg. the ppt. of ble fluo- fluorides rides mg.

392.3 5.98 4-0 2.64 2.1 4.74 391.0 10.0

392.3 5.98 4.0 2.64 2-64 4-86 391.4 9.95

392.3 5.98 4-0 2.64 3.0 5-57 390.5 10.02

392.3 5.98 4.0 2-64 4.04 6.68 .... *

392-3 5.98 4-0 2.64 4.43 6-80 .... *

392.3 5.98 4.0 2.64 5-26 ...... *

* Uranium got precipitated due to hydrolysis. TABLE II Effect of pH on the separation of uranium from iron

pH adjust- Initial pH after ed by am- U308 in U308 pH of H~O2 monia for the pre- Remarks mg. the solu- addi- preci- cipitate tion tion pitating mg. complex

392.3 5 -06 5.1 5" 14 .. Precipitation incomplete even on long standing

392"3 5.06 5.16 5"66 .. Precipitation incomplete

392-3 5.06 5.13 6.02 391.8

392"3 5-06 5.16 6-52 392"5

392-3 5"06 5.16 6-74 395.1 Values are high due to precipitation of iron

392.3 5.06 5.14 6-86 396-5 Values are high due tO precipitation of iron 22 N. S. KRISHNAPRASAD AND V. V. DADXPE

TABLB III

Concen- Oxidcs tratiort Ratio of Ratio of UnOa ThO~ ofrare Fe20 a ofU30 a UaOa[ThO2 UaOa/ UaOareco- mg. mg. earths mg. ii1 solu- +R.E. FeaO8 vered mg. mg. tion gln.] oxides litre

391.2 5-98 4"0 2.4 4.77 39.2 163.0 389.0 391.2 11-96 8.0 4.8 4.68 19.6 81 "5 390.2 391.2 23.92 16.0 9.6 4.45 9.8 40,8 389.8 391-2 47.84 32.0 19.2 4.07 4-9 20.4 392.0 195.6 119-6 80-0 19"2 2.45 0.98 10.2 197-0 97.8 119-6 80.0 19.2 1.63 0.49 5-1 97-4 48.9 299.0 200.0 48.9 0.45 0-098 1.0 48.2 foUowing result: UaOs 99.9~; Fe20~ 0-090~; SiO= 0.018~0; Rare earth oxides + ThO~ < 0.05~. CONCLUSIONS (I) Uranium is separated from thodum and rare earths from solutions containing as little as 0-45 g. U~Oa[litre and U~Oa/ThO2 + Rare earth oxides ----0-1 if the pH of the solution before adding KF or NH4F is about 3, or less. (2) Uranium is separated from iron in the pH range of 6 to 6-5 in solu- tions containing 0-45 g. U3Os/litre and UaOa/Fe~Oa = 1 "0.

(3) Complete separation of iron from uranium is aehieved only after washing the peroxy complex of uranium with a large volume of water.

Fuller details of the method wiU be published elsewhere.

ACKNOWLI~GEMENT The authors wish to thank Dr. Jagdish Shankar for his keen interest and helpful suggestions during the progress of this work. Preparation of Pure U308 from Crude Sodium Diuranate 23

REFERENCES 1. Bachelet, M., Cheylan, E. and J. Chito. Phys., 1947, 44, 302-05. Lebris, J. 2. Gibbs, H.L. .. U.S. Patent No. 1999807, 1935. 3. Grnelin's Handbuch der Anorganischen Chemie, Uran und Isotope, 1936, 55. 4. Rodden, C.J. .. Analytical Chemistry of the Manhattan Project, I950, 14-44. 5. Bolton, H.C. .. Z. Chem., 1866, 2 (2), 356. 6. Baker, H. .. J. Ch› Soc., 1879, 35, 760. 7. Katz, J. J. and Rabinovitch, E. The Chemistry of Uranit~m, 1951, 573.