Patented Jan. 2, 1951 2,536,347

UNITED STATES PATENT OFFICE . 2,536,34 PRODUCTION OF BASEC AMEMONUM URANY SULFATE AND URANUM OXDE Eugene O. Brimm, Kenmore, and Carleton N. Smith, Snyder, N. Y., assignors, by mesne as signments, to Union Carbide and Carbon Cor poration, a corporation of New York NoDrawing. Application October 14, 1944, Serial No. 558,726 4. Claims. (C. 23-145) 2. This invention relates to the manufacture of an alkali-containing uranium compound with oxides of uranium, and pertains more partic acid and an ammonium salt of such acid, while ularly to a method for making uranosic oxide maintaining the pH of such suspension or solu (U3O8) of a high degree of purity. tion within the range of 4 and 6, preferably Uranosic oxide may be produced by calcining 45 to 5. (heating in the air) tranium compounds which The proportion of annonium salt is not ordi contain no nonvolatile impurities, e. g. ammo narily Critical, except as explained hereinafter. nium diuranate, annonium uranyl carbonate, Good results are obtainable at annonium salt uranyl nitrate, uranyl sulfate, uranic acid, or concentrations corresponding to about 10% by uranium peroxide. 10 Weight of the water present; but this concern The usual processes for recovering uranium tration may be varied within wide limits, for from its ores yield a produce containing from example 5% to 15%. 32% to 10% sodium combined with the uranium The foregoing treatment may be conducted at as sodium uranate. As this sodium can not be room temperature, in which case it should Or. driven off by heat, its removal is a necessary 5 dinarily be continued for several hours, or at elie preliminary to the preparation of IranOsic oxide wated temperatures, e. g. 90° to 95 C., which by calcination. hasten the reactions. One method which has been proposed consists Upon completion of the reactions, the reac in digesting sodium uranate with a concentrated tion mixttire is filtered, ieaving a residue of solution of ammonium chloride, thereby replac 20 alkali-free uranium compounds. The residue ing the Sodium with an ammonium radical and may be Washed with hot water, preferably con producing sodium chloride which may be re taining ammonium Salt, for instance a 1% solu moved by filtration and washing. By repeating tion of the ammonium salt of the acid used in the digestion step several times, using fresh por the first, digesting, step. After washing, the tions of ammonium chloride Solution, nearly all 25 residue is dried and then calcined to produce of the sodium may be extracted and the result pure uranosic oxide, U3O8. Suitable calcining ing ammonium uranate may then be calcined to temperatures are those within the range 750° to obtain uranosic oxide, The principal short 9000 C. coming of this method for large scale use is that While Satisfactory results may be obtained it is slow and expensive. 30 With various acids, such as hydrochloric, nitric, Another method consists in dissolving the or acetic, superior results are obtainable by the Sodium uranate in acid and then adding annonia, use of Sulfuric acid and ammonium sulfate. to precipitate ammonium uranate. This method One reason for the particularly favorable re must likewise be repeated if a pure product is Sults of the use of sulfuric acid and ammonium desired. Sulfate is that, under the conditions just men A third method, described in Patent 120.714, 35 tioned, an insoluble basic ammonium uranyl Harvey A. Seil, comprises moistening sodium Sulfate is formed. This novel compound, the uranate with enough Sulfuric acid to combine existence of which we have verified by X-ray with the Sodium to form sodium sulfate or bi diffraction methods, has a formula, by analysis, sulfate, heating the resulting mixture, and ex 40 Corresponding approximately to tracting the sodium sulfate with water. This method may be used to remove most of the sodium, but it has a serious disadvantage in It is an Orange-yellow crystalline solid, insoluble that critical control of the time and temperature in Water but Soluble in dilute mineral acids. At of heating are necessary. Low temperatures or 45 temperatures above 100° C., the Water is re short times lead to incomplete removal of sodium moved to an extent dependent upon the temper and loss of uranium. On extraction. Too Ong a ature. The compound has no melting point, but time and too high a temperature result in in at high temperatures decomposes with loss of complete removal of sodium because of the re ammonia, and, at still higher temperatures loses action of sodium sulfate with uranosic oxide to 50 SO3, yielding uranosic oxide, U3O8. Decomposi form Sodiurn uranate. tion is rapid at 800° C. Or above, slower at According to this invention, the removal of 600-7000 C. Substantially all alkali metal is accomplished Other acids, such as nitric, hydrochloric, and without dissolving any great amount of uranium, acetic, do not form insoluble basic ammonium by treating (digesting) an aqueous Suspension of 55 uranyl compounds, but, rather, mixtures of 2,536,847 3 4. urany salts with hydrated uranic oxide and other sulfate which comprises mixing an acid soluble known compounds. oxidic uranium compound with sulfuric acid and Thus, in another aspect, this invention includes, ammonium sulfate, and maintaining the pH of as a new and useful composition of matter, basic the mixture between 4 and 6. ammonium uranyl sulfate, and a novel method 2. A method of making basic annonium uranyl of making such compound by reacting upon an sulfate which comprises mixing a hot aqueous acid-soluble oxidic uranic compound, such as So suspension of Sodium uranate with Sulfuric acid dium uranate, with sulfuric acid and ammonium. and ammonium sulfate, and maintaining the pH sulfate. of mixture between 4.5 and 5. To form the desired basic ammonium uranyl O sulfate, it is of course necessary that enough 3. A method of making uranosic oxide which ammonium sulfate be present in the reaction comprises treating a hot aqueous suspension of mixture to satisfy the formula, given above of such Sodium uranate with Sulfuric acid and am basic ammonium uranyl sulfate. An excess of monium sulfate at a pH between 4.5 and 5 to ammonium salt is preferred. form a water-insoluble basic ammonium uranyl In a typical specific application of this invene 5 Sulfate, filtering off the liquid, and calcining the tion, a quantity of powdered Sodium uranate basic ammonium uranylsulfate. (6.8% Na2O) corresponding to 2649 pounds of 4. A method of making uranosic oxide which U3O8 was added to a 10% solution of ammonium comprises treating in aqueous medium a uranate sulfate containing 1686 pounds of ammonium Sul 20 with an acid and an ammonium salt of Such acid, fate. The resulting aqueous Suspension was while maintaining the pH of said medium be heated to about 90° to 95° C. and sulfuric acid tween 4 and 6, filtering the liquid from the re was added slowly, as the suspension was stirred, sulting solid, and calcining said solid. until the pH remained constant at 4.4. The EUGENE O. BRIMM. product was filtered and the filter cake washed 25 CARLETON N. SMITH, With hot 1% ammonium sulfate Solution. The washed cake was dried, then calcined for about REFERENCES CTED an hour at 1000° C. The calcined product con The following references are of record in the tained 99.24% U3O8. and 0.03% Na2O. file of this patent: The loss of uranium by solution in the acid and 30 Salt solution is very slight, under least favorable Mellor, “Inorganic and Theoretical Chemistry,' conditions being under 1.5% and under best con vol. 12, page 108, Longmans, Green and Co., LOn ditions being 0.5% or less. Calcination readily don (1932). (Copy in Div. 59.) eliminates all of the ammonia and substantially Lowry, “Inorganic Chemistry,' page 174, Sec all of the Sulfur. Sulfur contents are Ordinarily 35 Ond edition (1931). MacMillan and Co., London. well under 0.1%. (Copy in Div. 59.) . . We claim: 1. A method of making basic ammonium uranyl