US2873167A - Processes of reclaiming uranium from solutions - Google Patents

Description

Feb. 10, 1959 R. ZUMWALT 2,

' PROCESSES OF RECLAIMING URANIUM FROM SOLUTIONS v Fi'led Sept. 9, 1944 6 Sheets-Sheet 2 DISSOLVING URANIUM METAL DEPOSITED ON STAINLESS STEEL COLLECTOR IN (I)HOT SOLUTION HNO3 (12%)0R (2) SOLUTION HC! (299a H202'(O.5%)OR (a) SOLUTION H 50 (18 99a H 0 (10%) CONDENSATE AND MAKE u m HNO3 OR SOLUTION (2) /-/c/ .2 H20? 0/? U0; (3) H2$O42H202 Fe 4" co N 0 EN 5 I NG EVAPORATING (I) HNO3 OR (2) HC/ e! H202 OR (3) H2804 8 H20 c0/vc/v m4 TED SOLUTION U02 Fe f-f-I- V Cr ff-l Ni f 'fi TO F U RT H ER 2 T R EAT M E N T F! INVENTOR.

[/0 0 R. Z um wa/ 7" BY 2 Z; 5

ATTORNEY Feb. 10, 1959 L. R. ZUMWALT 2,873,167

PROCESSES OF RECLAIMING URANIUM FROM SOLUTIONS Filed Sept. 9, 1944 6 Sheets-Sheet 3 STARTING MATERIAL FROM PRIOR Zg ZC TREATMENT H Fe ff-l- ADJUSTING PH 3 'ro o.|-o.s

N03 ,AND ADDING Na FSOLUTION I 2. 3 F/L nu TE Fe Cu Fe*** N, ff Cf PRECIPITATING 1 NaC H 0 AN D FILTERING 1 I PREC/P/ r4 TE 7 Na UO2(C2H302)3 TO DISCARD 1-' DISSOLVING 0R LVAGE D/LUTE HC/ SOLUTION U024!- I Na"' REDUCING UOZH' PRECIPITATING NH OH AND FILTERING PREC/P/ TA TE )4 TO DISCARD TO FURTHER OR SALVAGE TREATMENT INVENTOR. Z ii} u {j L/Oyd P. Zumwa/f am .42 M

ATTORNEY Feb. 10, 1959 L. R. ZUMWALT 2,873,167

PROCESSES OF RECLAIMING URANIUM FROM SOLUTIONS Filed Sept. 9, 1944 I 6 Sheets-Sheet 4 STARTING MATERIAL A FROM PRIOR TREATMENT CALCINING |1 -{DISCARD VAPOR/120 v GASES COClz W- REACTING 232 SUB Ll M l NG o IN VACUUM RES/DUE SALVAGE U0; U0 C/2 (SUBL/MA TE LU C74 1 E N D A P R O D U CT F1 4 INVENTOR. L/oyd A. Zumwa/f BY Ma M ' ATTORNEY.

Feb. 10, 1959 R. ZUMWALT 2,873,167

PROCESSES OF RECLAIMING URANIUM FROM SOLUTIONS Filed Sept. -9, 1944 6 Sheets-Sheet 5 SIMILAR SOLUTIONS STARTING STARTING MATERIAL MATERIAL FROM pR|QR T zjx fy f FROM PRIOR 338- "f" 3" PURIFICATION Z2 PURIFICATION 5 u TREATMENT 7 TREATMENT u u 44- 0 II l1 c0 ll ADJUSTING H ADJUSTING H ZNH4OH (3 5) I V F/L TRA r5 E T F/L m4 TE I 80*", Ni awtm'" T AGITATING DISCARD AglTATING} DISCARD AND FILTERING AND FILTERING FRESHLV PREC/P/TA TED PREC/P/TA r5 PREC/P/TA TE 3 50' c0; LARGE AMT. Ba e0 LARGE AMT.

B02 u0 0 SMALL BQ X JM Fe (Of/) 3 CI-(0H)3 I 93 Cu(0h')z );x

| CARR/ER //v FURTHER sow r/0/v I TREA TMENTS PREC/P/TA TE I 1 DISSOLVING I b1 50 AND HEATING sowrflv TO DISCARD O 5 OR SALVAGE Cr 4*, C ff PRECIPITATING T AND FILTERINGI m mm: 750 TA rss 402 2 7 Fe 33. v To D|scARD Cr 3 OR SALVAGE 1 TD- FURTHER 1 TREATMENT r MENTOR Fig.3

Lloyd A. Zumwa/f BY 4 4 M ATTORNEY.

Feb. '10, 1959 Filed Sept 9,

L. R.v ZUMWALT PROCESSES OF RECLAIMING URANIUM FROM SOLUTIONS 6 Sheets-Sheet 6 SOLUTION TO BE SALVAGED FOR U HETEROGENEOUS REDUCING AGENT z++ PRECIPITATEDON ca" REDUCING AGENT NOTE:

\ THIS REDUCTION OCCURS WHEN REDUCING AGENT HA5 SUFF/C/EN TLV LOW OX/DA T/ON P0 TEN TIAL SOLUTION U PRECIPITATING AND ABSORBING AGENT SOLUTION Jk TO TREATM ENT PRECIPITA TING AND ABSORB/NG AGENT WITH U(OH);,CY(OH)3, r Fe '92)( )2) TO DISCARD TO. RECOVER U RAN IUM Fig.5

IN PURIFIED FORM INVENIOR. Lloyd A. Zumwa/f M x ATTORNEY.

United States PatentO PROCESSES F RECLAllVIING URANIUM FROM SOLUTIONS Lloyd R. Zumwalt, Oak Ridge, Tenu., assignor to the United States of America as represented by the United States Atomic Energy Commission Application September 9, 1944, Serial No. 553,430 9 Claims. cl. 2s-14.s

issued on July 15, 1958 as U; S. Patent No. 2,843,451.

It is an object of the invention to provide an improved process of reclaiming uranium from a calutron.

Another object of the invention is to provide an improve-d process of salvaging fractions of uranium from solutions derived from a calutron, which solutions have been previously subjected to primary uranium recovery treatment.

A further object of the invention is to provide an improved process ofsalvaging fractions of uranium from solutions which have been previously subjected to primary uranium recovery treatment, in which the salvage solution is treated with a barium carbonate carrier.

A further object of the invention is to provide an improved process of salvaging fractions of uranium from solutions which have been previously subjected to primary uranium recovery treatment, in which the salvage solution is treated with a zinc hydroxide carrier.

A still further object of the invention is to provide an improved process of salvagingfractions of uranium from solutions which have been previously subjected to primary uranium recovery treatment, in which the salvage solution is treated in an extraction column.

The invention both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the following specification taken in connection with the accompanying drawings, in which Figure 1 illustrates a portion of the flow diagram of the present process, indicating the recovery of the residue of U01 from the parts of the calutron disposed in the source region thereof upon which it is deposited; Fig. 2 illustrates another portion of the fiow diagram of the present process, indicating the recovery of the metallic uranium from the collector of the calutron upon which it is deposited; Fig. 3 illustrates a further portion of the flow diagram of the present process, indicating the purification of the recovered uranium;

Fig. 4 illustrates a further portion of the flow diagram treatment, wherein a barium carbonate carrier is em-' ployed; and Fig. 6 illustrates a still further portion of the flow diagram of the present process, indicating another embodiment of the salvage of a fraction of uranium contained in materials which have been previously subjected to primary uranium recovery treatment, wherein an extraction column is employed.

2,873,167 Patented Feb. 10, 1959 of the character of that disclosed in the copending application of Ernest 0. Lawrence, Serial No. 557,784, filed October 9, 1944, which issued on May 24, 1955 as U. S. Patent No. 2,709,222, and is employed to separate the constituent isotopes of an element and more particularly to increase the proportion of a selected isotope in an element containing a plurality of isotopes, in order to produce the element enriched with the selected isotope. For example, the machine is especially useful in producing uranium enriched with U Such a calutron essentially comprises means forvaporizing a quantity of material containing an element which is to be enriched with a selected one of its several isotopes;

means for segregating the ions from the un-ionized vapor and for accelerating the segregated ions to relatively high velocities; electromagnetic means for deflecting the ions along curved paths, the radii of curvature of the paths of ions being proportional to the square roots of the masses of the ions, whereby the ions are concentrated produce uranium enriched in U UCI serves as the At the outset, it is noted that a calutron isa machine source material therein. In operation, UCL, is vaporized in, the source region of such a calutron. The. vaporized UCL,- is then ionized and the ions are accelerated through the calutron chamber where they undergo segregation under the influence of electromagnetic means and are subsequently deposited in collector pockets. I

More particularly, the minor fraction. of the UCI; vapor is ionized to form positive atomic ions including U+, U++, Cl+ and Cl++; and positive molecular ions including CI Cl UCl UCl UCl UC1 UCl UCl UC1+ and UCl++. Of these atomic and molecular ions only the singly ionized atomic ions U+ have the required ratiobetween mass and charge such that they are focused into several collector pockets formed into the receiver section of said calutron, the atomic ionsU+ of masses 234 and 235 focusing into a first pocket, and the atomic ions U+ of mass 238 focusing into a secondpocket.

The doubly ionized atomic ions U++ have such a ratio between mass and charge that they are deflected along an arc of shorter radius into engagement with the inner wall of the calutron chamber liner, where they are de-ionized to form a deposit thereon. The singly and doubly ionized atomic ions Cl+ and Cl++ and the singly and doubly ionized molecular ions Cl and Cl have such small ratios between mass and charge that they are deflected along arcs of very short radii into engagement with the inner wall of the chamber liner adjacent the source region, where they are de-ionized to form neutral chlorine molecules, which gas is subsequently pumped from the calutron chamber. Similarly, the doubly ionized molecular ions UCI UCl UCl and UCl++ have intermediate ratios between mass and charge suchthat they are deflected along arcs of intermediate radii into engagement with the inner wall of the calutron'chamber liner intermediate the source region andthe collector region, where they are dc-ionized to form a deposit thereon. Finally, the singly ionized molecular ions UCLJ', UCl UCl and UCl+ have large ratios between mass and charge, such that they are deflected along arcs of large radii into engagement with the outer wall of the calutron chamber liner inter- J mediate the source region and the collector region, where they are de-ionized to form a deposit thereon.

Accordingly, it will be understood that, after operation of a calutron to vaporize a reasonable number of charges of UCl a considerable deposit of UClJ, is formed on the adjacent end of the calutron chamber liner, and that a reasonable deposit of metallic uranium, as well as the various uranium chlorides, is formed on the intermediate portion of said chamber liner. These deposits represent uranium which contains the various isotopes U U and U in natural or normal amounts such that these deposits should be recovered for recycling purposes as well as to clean the liner and the other parts of the calutron in order to insure efiicient operation thereof.

Considering the present process in greater detail with reference to the production of uranium enriched with U it is pointed out that natural or normal uranium comprises three isotopes, U U and U in the approximate relative abundances 1, 1/139 and 1/ 16,700 (in numbers of atoms with reference to U respectively, or approximately 16,700, '120 and 1 atoms, re-

spectively, in 16,821 atoms of a sample. It is highly desirable to prepare large quantities of uranium enriched with the thermal-neutron fissionable isotope U for commercial purposes, and it has been found that this end can be accomplished by employing the calutron method. However, it is desirable that the uranium product have an enrichment factor with respect to U of the order of 400, this factor being defined as the quotient obtained by dividing the ratio of U' to U in the product with the ratio of U to U in the original material. Now assuming that the product is enriched by 400 in both U and U it comprises U U and U in the approximate relative abundances .1, 400/139 and 400/16,700 (in numbers of atoms with reference to U respectively, or approximately 16,700, 48,057 and 400 atoms, respectively, in 65,157 atoms of a sample. Thus the enriched uranium product comprises approximately 25.7% U 73.7% U and 0.6% U

In order to obtain this desired enrichment of the uranium product by utilizing the calutron method, it has been found most convenient to use first-stage and second-stage calutrons, the first-stage calutronsemploying natural or normal uranium and producing a firststage enriched product having an enrichment factor of the order of with respect to natural or normal uranium; and the second-stage calutrons employing firststage enriched uranium and producing a second-stage enriched product having anenrichment factor of the order of 20 with respect to the first-stage enriched uranium, whereby the second-stage enriched uranium product has a final. enrichment factor of the order of 400 with respect to natural or normal uranium. By employing the present process, whereby the ultimate enrichment of the final uranium product is obtained in two stages, as indicated above, each of the first-stage and the second-stage colutrons may be operated in the stable range and to give a maximum yield of enriched material.

Accordingly, in the present process it will be understood that in the event the, calutron comprises a first-stage calutron, the deposit of uranium formed in the second collector pocket has been impoverished with respect to the desired isotope U and is recovered therefrom and discarded; while the deposit of uranium formed in the first collector pocket has been singly enriched with respect to the desired istope U and is recovered therefrom and subsequently treated in a second-stage calutron. On the other hand, in the event the calutron comprises a secondstage calutron, the deposit of uranium formed in the second collector pocket has been first enriched and then impoverished with respect to the desired isototpe U and is recovered therefrom and analyzed for U' content to aerate determine its suitability for possible recycling in a firststage calutron; while the deposit of uranium formed in the first collector pocket has been doubly enriched with respect to the desired isotope U and is recovered therefrom for commercial use.

Thus it will be understood that in a first-stage calutron, the deposit of metallic uranium in the first pocket has been subjected to one treatment and is termed singly enriched uranium, the enrichment being with respect to the desired isotope, U on the other hand, in a second-stage calutron the deposit of metallic uranium in the first pocket has been subjected to two treatments, and is termed doubly enriched uranium, the enrichment being with respect to the desired isotope U Considering how the process in greater detail, it will be understood that a plant arranged to carry out the process will comprise a relatively large number of first-stage calutrons and a relatively small number of second-stage calutrons, in addition to facilities for handling, storing, recovering, purifying and converting the various metallic and compound forms of uranium. The starting material employed as a charge in the first-stage calutron is UCI comprising natural or normal uranium, whereby metallic uranium singly enriched with U is deposited in the first pocket of the collector and metallic uranium impoverished with respect to U is deposited in the second pocket of the collector. Also, a large amount of UCL; is deposited as a residue upon the parts of the first-stage calutron disposed in the source region thereof, the deposit being primarily on the source-region end of the liner. After several charges of UCl comprising natural or normal uranium, have been employed in the first-stage calutron, reasonable deposits of metallic uranium have been collected in the first and second pockets of the collector, and the metallic uranium deposits in the collector and the UCL, residue on the liner arerecovered.

More particularly, the metallic uranium singly enriched with U and deposited in the first pocket of the collector is recovered by an acid wash process, whereby various impurities including iron, chromium and nickel are introduced in the wash solution, due to the fact that the collector of the first-stage calutron which is thus washed with acid is formed of the metals mentioned. Accordingly, the wash solution containing the uranium singly enriched with U which has been reclaimed contains considerable impurities. This wash solution is stored and subseqently employed as makeup material in a purification process utilized in conjunction with the second-stage calutron, in a manner more fully explained hereinafter. The metallic uranium impoverished with respect to U and deposited in the second pocket of the collector is recovered by an acid wash process and discarded, as it contains so little U that further processing thereof is not feasible.

The residue of UCL, deposited on the parts of the first stage calutron disposed in the source region thereof, principally upon the liner, is recovered by a water wash process, whereby various impurities including copper, iron, chromium, nickel and carbon are introduced in the wash solution, due to the fact that the various parts of the firststage calutron which are thus washed with water are formed of the materials mentioned. Accordingly, the wash solution containing natural or normal uranium which has been reclaimed, contains considerable impurities. To this wash solution there is added makeup material in the form of a wash solution derived from the second-stage calutron, and comprising the wash solution from the second pocket of the collector, and containing uranium which I has been first enriched with U in the first-stage calutron amount of makeup UCL as a charge in the first-stage calutron.

Accordingly, the residue of UCL; deposited in the source region of the first-stage calutron is treated to render it recyclable therein; the first-stage enriched uranium is stored for use in the second-stage calutron; and the first-stage impoverished uranium is discarded.

The starting material employed as a charge in the second-stage calutron is UCl comprising singly enriched uranium, whereby metallic uranium doubly enriched with U is deposited in the first pocket of the collector and metallic uranium which has been first enriched in the first-stage calutron and then impoverished in the secondstage calutron is deposited in the second pocket of the collector. Also, a large amount of UCI is deposited as a residue upon the parts of the second-stage calutron disposed in the source region thereof, the deposit being primarily on the source-region end of the liner. After several charges of UCl comprising singly enriched uranium have been employed in the second-stage calutron, reasonable deposits of metallic uranium have been collected in the first and second pockets of the collector, and the metallic uranium deposits in the collector and the UCL; residue on the liner are recovered.

, More particularly, the metallic uranium doubly enriched with U and deposited in the first pocket of the collector is recovered by an acid wash process, whereby various impurities including iron, chromium and, nickel are introduced in the wash solution, due to the fact that the collector of the second-stage calutron which is thus washed with acid is formed of the metals mentioned. Accordingly, the wash solution containing the uranium doubly enriched with U which has been reclaimed contains considerable impurities. This wash solution is then purisecond pocket of the collector is recovered by an acid wash process, whereby various impurities including iron, chromium and nickel are introduced in the wash solution, due to the fact that the collector of the secondstage calutron which is thus washed with acid is formed of the metals mentioned. Accordingly, the wash solution containing the uranium first enriched with U and subsequently impoverished with respect to U which has been reclaimed contains considerable impurities. The uranium in the wash solution is then analyzed, and in the event it contains at least as much U as natural or normal uranium, it is employed as makeup material in the purification process utilized in conjunction with the first-stage calutron.

The residue of UCl deposited on the parts of the second-stage calutron disposed in the source region thereof, principally upon the liner, is recovered by a water wash process, whereby various impurities including copper, iron, chromium, nickel and carbon are introduced in the wash solution due to the fact that the various parts of the second-stage calutron which are thus washed with water are formed of the materials mentioned. Accordingly, the wash solution containing the singly enriched uranium which has been reclaimed contains considerable impurities. To this wash solution there is added the previously stored makeup material in the form of the wash solution derived from the first-stage calutron and comprising the acid wash solution from the first pocket of the collector of the first-stage calutron and containing singly enriched uranium. This composite wash solution is then purified in order to eliminate the impurities mentioned; the impurities thus eliminated are discarded or salvaged; and the uranium thus purified is then converted back to the compound UCl This compound of UCl is then employed as a charge in the second-stage calutron. 1 l

Accordingly, the residue of UCI deposited in the source region of the second-stage calutron is treated to render it recyclable therein; the second-stage enriched uranium is converted to a standard compound of uranium to'be used commercially; and the second-stage impoverished uranium is stored for use in the first-stage calutron.

Considering now the details of the recovery of the UCL; residue from the parts of either a first-stage or a second-stage calutron disposed in the source region thereof, reference is made to the portion of the flow diagram illustrated in Fig. 1. The parts of the calutron disposed in the source region thereof, principally the source-region end of the liner, are scrubbed and washed with hot water, whereby the residue of UCL; deposited thereon is dissolved; and various impurities including copper, iron, chromium, nickel and carbon, are introduced in the water wash, due to the fact that the various parts of the calutron which are thus washed with hot water are formed of the materials mentioned. The wash water is then sieved in order to remove any solid impurities which may be picked up, such, for example, as small pieces of metal and carbon. These solid impurities may be either discarded or subjected to salvage treatment in order to recover any occluded uranium. The sieved wash water is then treated with H 0 by adding a slight excess of ten percent H 0 and agitating the solution in order to oxidize the various contained materials. For example, prior to the step of oxidation the wash water may contain suspended U(OH) and bits of copper and carbon, dis solved uranium in the +4 and +6 valence states, as well as dissolved copper, iron, nickel, chromium and possibly other metals in one or more of the positive valence states. Hence, as a result of oxidation all of the uranium is put in solution as uranyl ion, suspended copper is put in solution as cupric ion, and other dissolved materials are put in their higher stable valence states, if they are not already in such states. Carbon is not oxidized by this treatment. The efiect of the oxidation on the various materials contained in the wash solution may be indicated as follows:

Accordingly, the oxidized wash water contains at least the following: UO Cu++, Fe+++, Cr+++, Ni++ and C (carbon). The oxidized wash water is then filtered in order to remove C, which may be discarded or subjected to salvage treatment in order to recover any occluded uranium.

In the event this filtrate is rather dilute, it may be concentrated by evaporation; otherwise, this step is omitted. In the event the filtrate is concentrated by evaporation, the water vapor which is driven off is condensed and to it is added enough makeup water in order to provide a new wash solution, which is used again to wash the parts of the calutron disposed in the source region thereof, in the manner previously explained. This step, comprising condensing and re-using the water vapor which is driven off the filtrate incident to concentration by evaporation, is advantageous in view of the fact that any uranium entrained in the water vapor is not lost tothe outside. The original filtrate mentioned above, or the concentrated filtrate following evaporation, in the event this step is employed, is then stored for further treatment.

It will be understood that the stored water wash derived from the parts of the first-stage calutron disposed in the source region thereof as explained above, comprises um nium of natural or normal composition with reference to U while the stored water wash derived from the parts of the second-stage calutron disposed in the source region thereof, as explained above, comprises uranium which is singly enriched with U Considering now the details of the recovery of the metallic uranium, singly enriched with U from the first pocket of the collector of the first-stage calutron, or of the metallic uranium, doubly enriched with U from the first pocket of the collector of the second-stage calutron, reference is made to the portion of the flow diagram illustrated in Fig. 2. The inner surfaces of the first pocket of the collector of the calutron are etched with one of a number of acid solutions, whereby the deposit of metallic uranium, either singly or doubly enriched with U is dissolved; and various impurities including iron, chromium and nickel are introduced in the acid wash solution, due to the fact that the inner surfaces of the first pocket of the collector of the calutron which are thus etched with the acid solution are formed of stainless steel which comprises the materials mentioned. Accordingly, the wash acid contains at least the following ions: UO Fe+++, Cr+++ and Ni++.

A suitable acid wash solution which may be employed for the purpose mentioned comprises an aqueous solution containing HNO (approximately 12%). Another suitable acid wash solution comprises an aqueous solution containing HCl (approximately 2%) and H (approximately 0.5%). A further suitable acid wash solution comprises an aqueous solution containing H 80 (approximately l8%) and H 0 (approximately 10%). Thus, it will be understood that the first acid wash soluti n comprises an oxidizing acid, whereas the second and third acid wash solutions comprise a separate oxidizing agent in the form of H 0 Hence, the acid wash solution employed in any case produces an oxidizing effect upon both the uranium and the metal impurities which are dissolved therein.

In the event the wash acid is rather dilute in the ions mentioned, it may be concentrated by evaporation; otherwise this step is omitted. In the event the Wash acid is concentrated 'by evaporation, the vapor which is driven olf is condensed and to it is added enough makeup HNO or HCl and H 0 or H 80 and H 0 depending upon the composition of the original wash acid employed, in order to provide a new wash acid which is again used to wash the first pocket of the collector of the calutron, in the manner previously explained. This step, comprising c ndensing the vapor which is driven off the wash acid incident to concentration by evaporation, is advantageous in view of the fact that any uranium entrained in the vapor is not lost to the outside. The original wash acid mentioned above, or the concentrated wash acid following evaporation, in the event this step is employed, is then stored for further treatment.

It will be understood that the stored acid wash derived from the first pocket of the collector of the first-stage calutron, as explained above, comprises uranium which is singly enriched with U while the stored acid wash derived from the first pocket of the collector of the sec-0ndstage calutron, as explained above, comprises uranium which is doubly enriched with U The metallic uranium, impoverished with respect to U and deposited in the second pocket of the collector 'of the first-stage calutron, may be recovered merely by etching the inner surfaces of the second pocket of this collector with a suitable wash acid of the character mentioned above, whereby this deposit of metallic uranium is dissolved. This acid wash is then discarded, as it contains so little U that further processing thereof is not feasible.

On the other hand, the metallic uranium which has been first enriched with respect to U and subsequently impoverished with respect to U and deposited in the second pocket of the collector of the second-stage calutron, may be recovered by etching the inner surfaces of the second pocket of this collector with a suitable wash acid of the character mentioned above, whereby this deposit of metallic uranium is dissolved; and various impurities, including iron, chromium and nickel are introduced in the acid wash solution, due to the fact that the inner surfaces of the second pocket of the collector of the calutron which are thus etched with the acid solution are formed of stainless steel which comprises the materials mentioned. Accordingly, the wash acid contains at least the following ions: UO Fe+++, Cr+++ and Ni The considerations concerning whether the wash acid should be concentrated are the same as those previously noted. In any case, either the original wash acid mentioned above, or the concentrated wash acid following evaporation, in the event this step is employed, is then analyzed in order to determine the U content thereof. In the event the analysis indicates that the U content of this Wash acid is at least as great as natural or normal uranium, it is stored for further treatment; on the other hand, in the event the analysis indicates that the U content of this wash acid is less than that of natural or normal uranium, it is discarded, as further processing thereof is not feasible.

To the stored water wash solution derived from the parts of the first-stage calutron disposed in the source region thereof, there is added the stored acid wash solution derived from the second pocket of the collector of the second-stage calutron in order to produce a first composite solution; this first composite solution comprises uranium of substantially natural or normal composition with reference to U Also, to the stored water wash solution derived from the parts of the second-stage calutron disposed in the source region thereof, there is added the stored acid wash solution derived from the first pocket of the collector of the first-stage calutron in order to produce a second composite solution; this second composite solution comprises uranium which is singly enriched with U Finally, the stored acid wash solution derived from the first pocket of the collector of the second-stage calutron constitutes a third composite solution; this third composite solution comprises uranium which is doubly enriched with U 7 Considering now the details of the purification of one of the composite solutions described above, comprising the following ions: UO Cu Fe+++, Cr' and Ni++, reference is made to the portion of the flow diagram illustrated in Fig. 3. The pH of the solution is adjusted within the approximate range 0.1 to 0.6 by the addition thereto of I-INO or NaOI-I, depending upon the original pH of the solution. The concentration of uranyl ion is Within the approximate range 0.6 to 0.2 molar. To ths solution there is then added NaNO or NaCl, whereby the concentration of sodium ion is brought within the approximate range 1.0 to 2.0 molar. The temperature of the solution is then adjusted to about room temperature, approximately F., and there is added thereto sufficient solid sodium acetate so that after precipitation of the uranium as sodium uranyl acetate the molar concentration ratio of acetic acid to acetate ion is within the approximate range 2.0 to 2.5 (i. e., the pH of the solution is within the approximate corresponding range 4.46 to 4.36). The procedure described above, wherein the sodium uranyl acetate is precipitated in the acetic acid solution of which the pH is approximately 4.46 to 4.36, is very advantageous in view of the fact that this acidity of the solution prevents the precipitation of slight traces of iron and other of the metal impurities. Normally Fe+++ precipitates at a substantially lower pH than that corresponding to the pH range just mentioned. However, in this case, apparently due to complexing with the acetate ion, the Fe+++ does not precipitate even at a pH of 4.46.

It will be noted that, according to the. foregoing procedure wherein NaNO or NaCl is added to the solution 9 prior to the sodium uranyl acetate precipitation step, advantage is taken of the common ion effect to increase the concentration of Na+ ion in the solution and thus to enhance the effectiveness of the uranium separation.

Instead of following the above procedure, wherein the solution is first acidified so that when sodium acetate is added thereto an acetic acid solution is formed, an alternative procedure may be followed. More particularly, the step of adjusting the pH of the original solution, in order to bring it to the stipulated acidity, may be omitted, and to the original solution there may be added directly a mixture of glacial acetic acid and solid sodium acetate, whereby the uranium is precipitated as sodium uranyl acetate, as previously noted. In this case, the ratio of the mixture of acetic acid and sodium acetate added to the original solution is such that after precipitation of the sodium uranyl acetate, the molar concentration ratio of acetic acid to acetate ion is within the approximate range 2.0 to 2.5 (i. e., the pH of the solution iswithin the approximate corresponding range 4.46 to 4.36), for

the purpose previously noted.

In any event, the uranium is precipitated as sodium uranyl acetate away from the metal impurities, such as copper, iron, chromium, nickel, etc., in the acetic acid solution, the ions Cu++, Fe+++, Cr+++, Ni++, etc., being highly soluble in the acetic acid solution. This procedure, utilizing the precipitation of uranium as sodium uranyl acetate in acetic acid solution, is very advantageous, in view of the fact that sodium uranyl acetate is insoluble to the approximate extent of 99.5% therein, While the acetates of the metal impurities mentioned are highly soluble therein.

The solution is then filtered and the sodium uranyl acetate precipitate is washed with an aqueous solution which is about 2.0 molar in sodium ion and 0.4 molar in acetic acid and about 0.2 molar in acetate ion. This washing of the sodium uranyl acetate with the aqueous solution mentioned carries any slight amounts of occluded metal impurities into the filtrate, and is of the required composition to prevent any appreciable dissolution of the sodium uranyl acetate precipitate. The filtrate containing the Cu++, Fe+++, Cr+++' and Ni++ ions is then discarded or subjected to salvage treatment in order to recover any uranium contained.

The effectiveness of the foregoing procedure in the reclamation of the uranium froma solution will be readily appreciated from the following example. A solution comprising about 9 liters containing approximately 950 grams of uranium, as uranyl nitrate, as well as ferric and chromic nitrates as impurities, was treated with nitric acid to bring the pH to about 0.3; and then about 850 grams of solid sodium nitrate was dissolved in the solution. Precipitation was brought about by adding approximately 1500 grams of anhydrous solid sodium ace- .tate to the solution and stirring. The solution was then filtered and the precipitate was washed with an aqueous solution which was approximately 2.5 molar in sodium ion and 0.4 molar in acetic acid and about 0.2 molar in acetate ion. The precipitate contained about 945 grams of uranium as sodium uranyl acetate, while the filtrate contained only about grams of the uranium and virtually all of the iron and chromium. Thus, a recovery of approximately 99.5% of the uranium from the solution was realized in this purification procedure.

The sodium uranyl acetate precipitate is then dissolved in dilute HCl, whereby the solution contains U0 and Na+ ions. The solution is then reduced in any suitable manner, whereby the uranium ion is reduced to its lower valence state. For example, the solution may be electrolytically reduced in the manner disclosed in the copending application of Martin D. Kamen, Serial No. 532,160, filed April 21, 1944, now abandoned.

The reduced solution now contains U++++ and Na+ ions, and is treated with NH OH in order to precipitate the uranium as U(OH) away from the sodium in the solution. The solution is then filtered andthe uranium hydroxide precipitate is washed with an aqueous solution containing about one percent NH OH and one percent NH Cl, carrying occluded sodium ion into the filtrate. The uranium thus purified and in the compound form U(OH) is then stored for further treatment or commercial use, as previously noted. The filtrate containing the Na+ ion is then discarded or subjected to salvage treatment in order to recover any uranium contained.

It will be understood that the purification of the first composite solution in the manner described above is productive of a first batch of U(OH) containing uranium of substantially natural or normal composition with reference .to U Also, the purification of the second composite solution in the manner described above is productive of a second batch of U(O H) containing uranium which is singly emiched with U Finally,the purification of the third composite solution in the manner described above is productive of a third batch of U(OH) containing uranium which is doubly enriched with U The first and second batches of U(OH) are then converted back to UCL, for re-treatment in the first-stage and second-stage calutrons, respectively; while the third batch of U(OH) is available for commercial use.

Considering now the details of the ultimate conversion of either the first batch or the second batch of U(OH) to UCl,, reference is made to the portion of the flow diagram illustrated in Fig. 4. More particularly, a batch of,U(OH) is calcined in an inert or reducing atmosphere, such as nitrogen or hydrogen, at approximately 250 C. in order to produce U0 whereby water vapor is given off incident to the calcination. The uranium dioxide is then reacted with CCl, in the vapor phase at approximately 450 C. in a suitable reaction chamber, in order to produce crude UCl whereby COCl CO CO and C1 gases are given off incident to the reaction. The crude uranium tetrachloride thus produced is then sublimed in a suitable molecular still at approximately 600 C. in order to produce a sublimate of UCl whereby residues of U0 and UOClare produced incident to the sublimation. The residues of U0 and UOCl are ultimately converted to UCl The UCl thus produced is of very pure form and is suitable for recycling in the appropriate one of the first-stage or second-stage calutrons, in the manner previously explained. More particularly, the conversion of the first batch of U(OH) is productive of a first batch of UCl containing uranium of substantially natural or normal composition with reference to U this first batch of UCL; is recycled in the firststage calutron. Also, the conversion of the second batch of U )H) is productive of a second batch of UCI containing uranium singly enriched with U this second batch of UCl, is recycled in the second-stage calutron.

The herein described process of recovering uranium from wash solutions derived from calutrons is very effective, in view of the fact that the precipitation of uranium as sodium uranyl acetate is a highly selective and specific reaction for uranium. Thus, not only may uranium be reclaimed from a wash solution containing the impurities mentioned, copper, iron, chromium and nickel, but the wash solution may contain a very large variety of other impurities, such as manganese, without interfering with the separation of uranium as sodium uranyl acetate. Moreover, the purification can be carried out as explained without particular reference to the identification of the impurities or the proportions contained in the wash solution; this feature is very advantageous, in view of the fact that both the particular impurities as well as the related quantities thereof vary considerably among the different wash solutions derived from the diiferent calutrons.

In carrying out the herein described process it is again noted that in the purification of the second composite solution, produced from the acid wash derived from the first pocket of the collector of the first-stage calutron and the water wash derived from the source 11 region of the second-stage calutron, and in the subsequent conversion of this second composite solution to produce a correspondingsecond batch of UC1, uranium is processed which has 'been singly enriched with U235v Similarly, in the purification of the third composite solution, produced from the acid wash derived from the first pocket of the collector of the second-stage calutron, uranium is processed which has been doubly enriched with U In view of the fact that the uranium con tained in these two composite solutions has been either singly or doubly enriched with U it is very valuable, and it is essential that none of this uranium be lost. Accordingly, all precipitates and filtrates produced incident to processing the solutions mentioned, which might contain some of this uranium, are subjected to salvage treatment in order substantially completely to reclaim any fractions of the contained uranium.

Considering now the details of the salvage of small fractions of uranium contained in various materials produced incident to carrying out the process, reference is made to the portion of the flow diagram illustrated in Fig. 5, wherein the barium carbonate carrier process is indicated. More particularly, in the event the material which is to be subjected to salvage treatment is in solid form, it is first dissolved in HCl, thereby to obtain an acidified salvage solution. On the other hand, in the event the material which is to be subjected to salvage treatment is in liquid form it is first treated with l-lCl. thereby to obtain an acidified salvage solution. In any case, an acidified salvage solution is produced which might contain, for example, UO Fe+++, Cr+++. Ni++ and Cur ions, all of the ions being in very dilute concentrations. The pH of the salvage solution is adjusted to a value approximately 3 to 5 by adding HCl or Nli Ol-l, as required.

The acidified salvage solution is then divided into number of portions of appropriate volume for handling purposes, and to a first of these portions there is added a quantity of freshly precipitated BaCO that is large relative to the uranium, iron, chromium and copper content of the solution undergoing treatment. T he solution is stirred, whereby the uranium is precipitated as Ba. UO (CO and the iron, chromium and copper are respectively precipitated as Fe(OH) Cr(OH) and CutOl-D away from the Ba+ and Ni++ ions in the solution. The solution is then filtered, whereby the barium carbonate carries the precipitate of barium uranyl. carbonate, ferric hydroxide, chromic hydroxide and cupric hydroxide, leaving the barium and nickelous ions, Ba++ and Ni in the filtrate. The precipitate is washed with an aqueous solution containing about one percent NH Cl in order to eliminate any occluded barium and. nickelous ions. It is noted that the barium carbonate precipitate not only carries the precipitate mentioned, but it also carries. due to surface action, any small amounts of uranium, iron, chromium and copper which are not precipitated as explained above. The filtrate containing the ions mentioned is discarded, and the barium carbonate precipitate carrying the barium uranyl carbonate, ferric hydroxide, chromic hydroxide and. cupric hydroxide is conserved for further use.

The above described cycle is repeated in conjunction with the several portions of the salvage solution, whereby the previously mentioned barium carbonate precipitate is employed to carry uranium. iron, chromium and copper from the several portions of the salvage solution, and is thus repeatedly used until it carries a considerable amount of uranium and the metals mentioned; and thereafter the uranium carried by the barium carbonate precipitate is recovered. More particularly, the body of barium carbonate precipitate is treated with an excess of 6 N H 50 whereby the barium carbonate and the barium uranyl carbonate are decomposed, BaSO, is precipitated, and the ferric, chromic and cupric hydroxides are put in solution, CO gas being given off incident to the decomposition of barium carbonate and the barium uranyl carbonate. The solution is heated to effect substantially complete liberation of the carbon dioxide gas. The solution is then filtered and the precipitate washed with an aqueous solution containing about one percent (NH SO whereby the barium sulfate precipitate is separated from the'filtrate containing UO Fe+++, Cr+++ and Cu++ ions. 7

The barium sulfate precipitate is then discarded or subjected to salvage treatment in order to recover any occluded uranium, and the filtrate containing the UO Fe+++, Cr+++ and C11 ions is subjected to. ammonia treatment either with NH gas or carbonate-free Nl-l OH. whereby the uranium is precipitated as (NHQ U O along with Fe(OH) and Cr(OH) away from the complex cupric ammonio ion, Cu(NI-I The solution is then filtered and washed with an aqueous solution containing about one percent NH OH and one percent NH NO in order to eliminate any occluded complex cu pric ammonio ion from the precipitate. The filtrate containing the complex cupric .ammonio ion, Cu(Nl-I is then discarded or subjected to salvage treatment in order to recover any contained uranium, and the precipitate of ammonium diuranate, ferric hydroxide and chromic hydroxide is conserved for further treatment.

- It will be understood that when a first salvage solution containing a fraction of uranium which is singly enriched with U is subjected to the barium carbonate carrier treatment described above, a first body of precipitate containing (NH U O is produced comprising uranium of like isotopic composition. Also, when a second salvage solution containing a. fraction of uranium which is doubly enriched with U is subjected to the barium carbonate carrier treatment described above, a second body of precipitate containing (NHQ U O is produced comprising uranium of like isotopic composition. These bodies of precipitate may be subjected to further purification treatment or they may be combined with appro priate ones of the acid and water wash solutions. For example, the first body of precipitate may be combined with the water wash solution derived from the source region of the second-stage calutron; while the second body of precipitate may be combined with the acid wash solution derived from the first pocket of the collector of the second-stage calutron.

Accordingly, when the different portions of the salvage solution are treated with the body of barium carbonate precipitate, not only are uranium, iron, chromium and copper extracted therefrom by the body of barium carbonate precipitate, but also such impurities as nickel are separated from the uranium in the different portions of the salvage solution incident to the extraction. Moreover, any uranium in the different portions of the salvage solution which is reduced to the uranous ion, U++++, is precipitated by the body of barium carbonate precipitate as U(OH )4 and carried thereby, along with the Ba UO (CO resulting from the precipitation of the uranyl ion UO Thus the body of barium carbonate precipitate carries not only the Ba UO (CO precipitate, but also, due to surface action, any small amount of U(OH)., precipitate as well as small amounts of uranyl and uranous ions which are not precipitated.

Reconsidering the details of the salvage of small fractions of uranium contained in various materials produced incident to carrying out the process, reference is made to the portion of the flow diagram illustrated in Fig. 6. wherein the extraction column process is indicated. More particularly, in the event the material which is to be subjected to salvage treatment is in solid form it is first dissolved in dilute HCl or HNO thereby to obtain a saL vage solution. On the other hand, in the event the material which is to be subjected to salvage treatment is in liquid form it is ready for treatment. In any case, a salvage solution is produced which might contain, for example, UO FE+++, Cr+++, Cu++, Nn and Mn++ ions, all of the ions being in very dilute concentrations.

The pH of the salvage solution is adjusted to a value approximately 2 to 4 by adding HCl or NH OH, as required.

The salvage solution is then poured through a vertical extraction column, whereby it is treated as it flows therethrough. In the event the salvage solution does not drain through the extraction column at the required rate, suction may be applied to the bottom of thecolumn in order to increase the rate of flow of the salvage solution therethrough. Preferably, the extraction column comprises a glass tube containing a composite packingincluding a number of adjacent individual packings orlayers. More specifically, the uppermost part of the composite packing comprises a relatively thick layer or packing of steel wool, which is followed by a thin layer or packing of loose asbestos fiber, then a relatively thick layer or packing of BaCO and then a thin layer or packing of loose asbestos fiber. Finally, the lowermost part of the composite packing comprises a relatively thick layer or packing of glass wool, the last-mentioned layer or packing supportingthe previously-mentioned layers or packings. Accordingly, the composite packing comprises, from top to bottom, a layer of steel wool, a first layer of asbestos, a layer of barium carbonate, a second layer of asbestos, and a layer of glass wool. The layer of steel wool is employed to provide a reducing action on certain of the ions in the dilute salvage solution which is passed through the glass column; the layer of barium carbonate is employed to provide a precipitating and absorbing action on certain of the ions in the dilute salvage solution which is passed through the glass column; the first and second layers of asbestos are employed to confine the layer of barium carbonate therebetween in position in the glass column; and the layer of glass wool is employed to support the various layers mentioned arranged thereabove in the glass column.

Considering now the operation of the column, when the dilute salvage solution encounters the layer of steel wool, the contained cupric ion, Cu++, is completely reduced to the metal state, u, and adheres thereto; the uranyl ion, UO is reduced to the uranous ion, U++++; and the ferric ion, Fe+++, is reduced to the ferrous ion, Fe++; whereby the solution penetrating the first asbestos layer contains U++++, Cr+++, Fe++, Ni++ and Mn. When the solution containing the ions mentioned passes through the first asbestos layer, it encounters the layer of BaCO whereby the uranous ion, U++++, is precipitated as U(OH) the ferrous ion, Fe is precipitated as Fe(OH) and the chromic ion, Cr+++, is precipitated as Cr(OH) away from the Ni++ and Mn++ ions in the solution. The uranous hydroxide, ferrous hydroxide and chromic hydroxide thus precipitated adhere to the barium carbonate in the layer, while the hydroxides of the divalent Ni++ and Mn++ ions are not sufliciently insoluble to be precipitated by barium carbonate. Accordingly, the solution containing the Ni++ and Mn++ ions is washed through the barium carbonate layer and thence through the second asbestos layer and the glass wool layer, out of the lower end of the glass column, the solution washed out of the lower end of the glass column being discarded.

Accordingly, when the dilute salvage solution is treated in the extraction column in the manner described, not only is uranium extracted therefrom by, the barium carbonate layer, but also such impurities as copper, nickel and manganese are separated from the uranium in the salvage solution incident to the extraction. Moreover, any uranium in the salvage solution which is not reduced to the uranous ion, U++++, and precipitated by the barium carbonate layer as U(OH) in the manner explained above, will remain as the uranyl ion, UO and will be precipitated as Ba UO- (CO by the barium carbonate layer. Thus the barium carbonate layer absorbs not only the U(OH) precipitate, but also any small amount of Ba UO (CO precipitate, as well as small amounts of uranous and iiranyl ions which are not precipitated, due to surface action. I After a suflicient quantity of the dilute salvage solution has been poured through the glass column in order layer is considered to contain a reasonably substantial quantity or amount of uranium hydroxide when a relatively broad band or ring of greenish appearance is observed in the upper end thereof proceeding toward the lower end thereof. The conserved barium carbonate upon which the uranous hydroxide, ferrous hydroxide and chromic hydroxide are absorbed is then treated with H whereby the barium carbonate is decomposed,BaSO., is precipitated, and the uranous, ferrous and chromic hydroxides are put in solution, CO gas being given off incident to the decomposition of the barium carbonate. The solution is heated to effect substantially complete liberation of the carbon dioxide gas. The solution is then filtered and the precipitate washedwith an aqueous solution containing about one percent (NH SO whereby the barium sulfate precipitate is separated from the filtrate containing U++++, Cr+++, Fe++ and possibly some Fe+++ and U0 ions.

- The barium sulfate precipitate is then discarded or subjected to salvage treatment in order to recover any occluded uranium, and the filtrate containing the U++++, UO Fe++, Fe+++ and Cr+++ ions is subjected to ammonia treatment either with NH gas or carbonatefree NH OH, whereby the uranium is precipitated as U(OH) and (NH4)2UQO7 along with Fe(OH) Fe(OH) and CR(OH) The mixture is then filtered; the filtrate is then discarded or subjected to salvage treatment in order to recover any contained uranium, and the precipitate of uranous hydroxide, ammonium diuranate, ferrous hydroxide, ferric hydroxide and chromic hydroxide is conserved for further treatment.

It will be understood that when a first salvage solution containing a fraction of uranium which is singly enriched with U is subjected to the extraction column treatment described above, a first body of precipitate containing U(OH) and (NI-I U O is produced comprising uranium of like isotopic composition. Also, when a second salvage solution containing a fraction of uranium which is doubly enriched with U? is subjected to the extraction column treatment described above, a second body of precipitate containing U(OH) and (NH,,) U O is produced comprising uranium of like isotopic composition. These bodies of precipitate may be subjected to further purification treatment or they may be combined with appropriate ones of the acid and water wash solutions. For example, the first body of precipitate may be combined with the water wash solution derived from the source region of the second-stage calutron; while the second body of precipitate may be combined with the acid wash solution derived from the first pocket of the collector of the secondstage calutron.

The extraction column process described above may be modified in various particulars while preserving the advantages described. For example, insead of employing a packing of steel wool, a packing of comminuted zinc may be substituted therefor. In this case, the comminuted zinc serves as a reducing agent in the manner previously explained. However, the zinc has an oxidation potential higher than that of iron and suz'ficiently high to reduce the chromic ion, Cr+++, in the salvage solution to the chromous ion, Cr++. In this case, when the solution containing U++++, Fe++, Ni++, Mn++ and Cr, ions (as well as any Cr ions resulting from 'tuted therefor a packing of Zn(OH) incomplete reduction and/or from the subsequent slow oxidation of Cr' by the water present in the system) encounters the barium carbonate packing, the uranous ion, U++++, is precipitated as U (OH) in the manner previously explained. Also, the ferrous ion, Fe++, is precipitated as Fe(OH) the chromous ion, Cr++, is precipitated as C1'(OH) and any chromic ion, Cr+++, that is present is precipitated as Cr(OH) while the solution, containing the Ni++ and Mn ions, is washed through the barium carbonate packing. The subsequent recovery of the uranous hydroxide from the barium carbonate precipitate is the same as that previously explained.

Furthermore, instead of employing a packing of barium carbonate in the column, there may be substi- In this case, the precipitation of the uranous ion, U++++, as U(OH) is the same as that previously explained. Also in this case, the trivalent chromic ion, Cr+++, is precipitated as Cr(OI-I) ferrous ion, Fe is precipitated as Fe(OH) and the divalent ehromous ion, Cr++, is likewise precipitated, as previously explained. Furthermore, any'uranium in the salvage solution which is not reduce to the uranous ion, U++++, and precipitated by the zinc hydroxide layer as U(OH) in the manner explained above, will remain as the uranyl ion, U and will be precipi- 'tated as ZnU O by the zinc hydroxide layer. Thus, the

zinc hydroxide layer absorbs not only the U(OH)4 precipitate, but also, due to surface action, any small amount of ZHUZO'? precipitate, as well as small amounts of uranous and uranyl ions which are not precipitated. Accordingly, it will be seen that, as compounds suitable for taking up the uranium, there may be employed sparingly soluble weakly-basic compounds capable of forming insoluble compounds with uranium, of which barium carbonate and zinc hydroxide are examples.

Furthermore, it is to be understood that the uranium salvage treatment proper, as described in detail in conjunction with Figs. 5 and 6; may be applied to uraniumcontaining solutions obtained as a result of any other desired primary treatment and which contain uranium in sufiicient concentration and/or in sufliciently valuable isotopic form or forms as to render the ultimate recovery thereof economically justifiable. Hence it will be understood that the primary treatment'described more particularly in conjunction with Figs. 1 to 4 represents, for purposes of illustration, but one of the many ways in which uranium solutions suitable for salvage operations may be obtained, and to which the salvage methods of the present invention are particularly applicable.

In view of the foregoing, it is apparent that there has been provided an improved process of recovering, reclaiming, salvaging, purifying and coverting uranium, both in metallic and compound forms, in conjunction with the calutron method, whereby uranium enriched with U may be produced on a large scale in commercial quantities.

Also it will be understood that the present process may be suitably modified so that a compound of uranium other than UCl may be treated either in the first-stage or in the second-stage calutron. For example, the calutron as well as the conversion steps of the process may be modified, whereby UCI UBr etc., may be treated in order to produce uranium enriched with U The term uranium is employed in the present specification and claims in a generic sense; i. e., as applying to uranium whether present in elemental, ionic or compound form, unless indicated otherwise by the context.

While there has been described what is at present considered to be the preferred embodiment of the invention, it will he understood that various modifications may be made therein and it is intended to cover in the appended claims all such modifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. In a process of reclaiming residual uranium values 16 from a salvage solution which also contains ions of the group consisting of Pe+++, Cr+++, Cu++, Ni++, and Mn ions, the step comprising adjusting the pH of said solution to a value of approximately 2 to 4, contacting said solution with metallic zinc to reduce the copper to "the metal state which adheres thereto and is removed from the solution and whereby the uranyl ions are reduced to the uranous state, contacting the reduced solution with a previously prepared zinc hydroxide precipitate to'precipitate and carry uranium, iron, and chromium ions away from Ni++ and Mn++ ions in the solution, separating said precipitate carrying uranium, iron and chromium from the solution, and recovering uranium from the precipitate.

2. In a process for recovering uranium values from a very dilute salvage solution containing uranyl ions and ions of the group consisting of Pe Cr+++, Cu++, Ni, and Mn++ ions, the steps comprising contacting the solution with a metallic reductant of the group consisting of iron and zinc to'reduce the cupric ions to the metal state which adheres to the reductant and is removed from the solution and whereby uranyl ions are reduced to the uranous state, contacting the reduced solution with a relatively large quantity of a previously prepared precipitate ot the group consisting of barium earbonate and zinc hydroxide to precipitate and carry uranium, iron, and chromium ions away from Ni++ and Mn++ ions in the solution, separating said precipitate carrying uranium, iron and chromium from the solution, and recover-ing'the uranium from the precipitate.

3. The process as delined in claim 2, wherein said reductant comprises Zinc and said previously prepared precipitate comprises zinc hydroxide.

4. In a process for recovering uranium values from a very dilute salvage solution containing uranyl ions and ions of the group consisting of Fe Cr+++, Cu' Ni++, and Mn++ ions, the steps comprising adjusting the pH of the solution to a value of approximately 2 to 4, contacting the solution with a metallic reductant of the group consisting of iron and zinc to reduce the cupric ions to the metal state which adheres thereto and is removed from the solution and whereby the uranyl ions are reduced to the uranous state, contacting the reduced solution with a relatively large quantity of previously prepared barium carbonate to precipitate and carry uranium, iron and chromium ions away from Ni++ and Mn++ ions in the solution, separating said precipitate carrying uranium, iron and chromium from the solution, and recovering the uranium from the precipitate.

5. The process as defined in claim 2, wherein said reductant comprises a porous mass of iron metal and wherein said previously prepared precipitate comprises barium carbonate.

6. In a process for recovering uranium values from a dilute salvage solution containing uranyl ions and ions of the group consisting of Fe+++, Cr+++, Cu++, Ni++ and Mn++ ions, the steps comprising adjusting the pH of the solution to a value of approximately 2 to 4, contacting the solution with a metallic reductant of the group consisting of iron and zinc to reduce the cupric ions to the metal state which adheres thereto and whereby the uranyl ions are reduced to the uranous state, contacting the reduced solution with a relatively large quantity of previously prepared barium carbonate precipitate to precipitate and carry uranium, iron and chromium ions away from any Ni++ and Mn++ ions present in the solution, separating said precipitate carrying uranium, iron and chromium from the solution, treating the precipitate with sulfuric acid and with heating to decompose the barium compounds present in the precipitate with the resultant precipitation of barium as barium sulfate from the solution and to dissolve the uranium, iron and chromium from the precipitate, separating the barium sulfate from the solution, and precipitating the uranium, iron and chromium from the solution with ammonia.

References Cited in the file of this patent UNITED STATES PATENTS 1,059,531 Ebler Apr. 22, 1913 1,137,871 Lawton May 4, 1915 1,251,564 Parkin Jan. 1, 1918 18 OTHER REFERENCES Britt-on: Hydrogen Ions, p. 278, publ. by D. Van Nostrand, N. Y. 1

Friend: Textbook of Inorganic Chemistry, vol. VII, part III, p. 302 (1926.)

Mellor: Inorganic and Theoretical Chemistry, vol. 4, p. 63, Longmans, London (1923.)

Freundlick: Colloid and Capillary Chemistry, pp. 220222, E. P. Dutton & Co., N. Y. Received in library 1930.

Mellor: Inorganic and Theoretical Chemistry, vol. 12, p. 116, Longmans, London (1932.)

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