US2902340A - Chemical method of treating fissionable material - Google Patents
Chemical method of treating fissionable material Download PDFInfo
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- US2902340A US2902340A US586619A US58661945A US2902340A US 2902340 A US2902340 A US 2902340A US 586619 A US586619 A US 586619A US 58661945 A US58661945 A US 58661945A US 2902340 A US2902340 A US 2902340A
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- 238000000034 method Methods 0.000 title claims description 23
- 239000000463 material Substances 0.000 title description 4
- 239000000126 substance Substances 0.000 title description 2
- 229910052778 Plutonium Inorganic materials 0.000 claims description 60
- BDAGIHXWWSANSR-UHFFFAOYSA-N Formic acid Chemical compound OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 claims description 59
- OYEHPCDNVJXUIW-UHFFFAOYSA-N plutonium atom Chemical compound [Pu] OYEHPCDNVJXUIW-UHFFFAOYSA-N 0.000 claims description 58
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 45
- 229910017604 nitric acid Inorganic materials 0.000 claims description 44
- 235000019253 formic acid Nutrition 0.000 claims description 29
- 230000008569 process Effects 0.000 claims description 18
- 238000011084 recovery Methods 0.000 claims description 6
- -1 PLUTONIUM IONS Chemical class 0.000 claims description 2
- 239000000243 solution Substances 0.000 description 59
- 229940076400 plutonium Drugs 0.000 description 57
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 description 28
- 229910002007 uranyl nitrate Inorganic materials 0.000 description 13
- 230000004992 fission Effects 0.000 description 12
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 10
- 229910052770 Uranium Inorganic materials 0.000 description 10
- JFALSRSLKYAFGM-UHFFFAOYSA-N uranium(0) Chemical compound [U] JFALSRSLKYAFGM-UHFFFAOYSA-N 0.000 description 10
- 239000000047 product Substances 0.000 description 9
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 6
- 150000001212 Plutonium Chemical class 0.000 description 6
- 239000012634 fragment Substances 0.000 description 6
- 230000009467 reduction Effects 0.000 description 6
- VEMKTZHHVJILDY-PMACEKPBSA-N (5-benzylfuran-3-yl)methyl (1r,3s)-2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropane-1-carboxylate Chemical compound CC1(C)[C@@H](C=C(C)C)[C@H]1C(=O)OCC1=COC(CC=2C=CC=CC=2)=C1 VEMKTZHHVJILDY-PMACEKPBSA-N 0.000 description 5
- 239000003638 chemical reducing agent Substances 0.000 description 5
- 238000001556 precipitation Methods 0.000 description 5
- 229940077390 uranyl nitrate hexahydrate Drugs 0.000 description 5
- 239000003463 adsorbent Substances 0.000 description 4
- SFOQXWSZZPWNCL-UHFFFAOYSA-K bismuth;phosphate Chemical compound [Bi+3].[O-]P([O-])([O-])=O SFOQXWSZZPWNCL-UHFFFAOYSA-K 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
- 230000003647 oxidation Effects 0.000 description 4
- 238000007254 oxidation reaction Methods 0.000 description 4
- 238000001179 sorption measurement Methods 0.000 description 4
- 239000002253 acid Substances 0.000 description 3
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 3
- 238000009835 boiling Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000005258 radioactive decay Effects 0.000 description 2
- 230000002285 radioactive effect Effects 0.000 description 2
- RZVAJINKPMORJF-UHFFFAOYSA-N Acetaminophen Chemical compound CC(=O)NC1=CC=C(O)C=C1 RZVAJINKPMORJF-UHFFFAOYSA-N 0.000 description 1
- 229910052684 Cerium Inorganic materials 0.000 description 1
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 1
- 229910052779 Neodymium Inorganic materials 0.000 description 1
- 229910052781 Neptunium Inorganic materials 0.000 description 1
- 241000643898 Plutonium Species 0.000 description 1
- 229910052777 Praseodymium Inorganic materials 0.000 description 1
- 229910052768 actinide Inorganic materials 0.000 description 1
- 150000001255 actinides Chemical class 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 238000013019 agitation Methods 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 229920001429 chelating resin Polymers 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000007859 condensation product Substances 0.000 description 1
- 230000002939 deleterious effect Effects 0.000 description 1
- 238000010790 dilution Methods 0.000 description 1
- 239000012895 dilution Substances 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 229910001448 ferrous ion Inorganic materials 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 150000004687 hexahydrates Chemical class 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 229910052746 lanthanum Inorganic materials 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- LFNLGNPSGWYGGD-UHFFFAOYSA-N neptunium atom Chemical compound [Np] LFNLGNPSGWYGGD-UHFFFAOYSA-N 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 150000002989 phenols Chemical class 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 239000012857 radioactive material Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229910052703 rhodium Inorganic materials 0.000 description 1
- 229910052707 ruthenium Inorganic materials 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- WBHQBSYUUJJSRZ-UHFFFAOYSA-M sodium bisulfate Chemical compound [Na+].OS([O-])(=O)=O WBHQBSYUUJJSRZ-UHFFFAOYSA-M 0.000 description 1
- 230000002277 temperature effect Effects 0.000 description 1
- JFALSRSLKYAFGM-OIOBTWANSA-N uranium-235 Chemical class [235U] JFALSRSLKYAFGM-OIOBTWANSA-N 0.000 description 1
- 125000005289 uranyl group Chemical group 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G56/00—Compounds of transuranic elements
- C01G56/004—Compounds of plutonium
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
Definitions
- This invention relates to an improvement in the process of preparing a pure fissionable element.
- the fission fragments include two general element groups, a light fission fragment group such as Br, Kr, Rb, Sr, Y, Zr, Cb, Mo, 43, Ru, and Rh, and a heavy fission fragment group such as Sb, Te, I, Xe, Cs, Ba, La, Ce, Pr and Nd.
- a light fission fragment group such as Br, Kr, Rb, Sr, Y, Zr, Cb, Mo, 43, Ru, and Rh
- a heavy fission fragment group such as Sb, Te, I, Xe, Cs, Ba, La, Ce, Pr and Nd.
- the oxidized plutonium can be reduced by means of a number of specific reducing agents such as ferrous ion, uranous ion, and the like. These reducing agents, however, introduce foreign elements that must themselves be removed before plutonium can be recovered in pure form.
- Formic acid is a reducing agent that is capable of reducing plutonium in its higher oxidation state to a valence state not greater than 4.
- the formic acid destroys excess nitric acid present by reacting with nitric acid probably in accordance with the following equation:
- nitric acid When the neutron bombarded uranium is dissolved in nitric acid, usually a sutficient excess of concentrated nitric acid is used so as to give a solution containing about.70 percent uranyl nitrate. In its further treatment, the solution may be diluted to give a lower uranyl nitrate concentration, for example, 40 percent or 20 percent with corresponding decrease in nitric acid concentration.
- the action of formic acid varies with the concentration of the solutions treated. With a concentration of 70 percent uranyl nitrate, the reduction proceeds vigorously; with 40 percent solutions, the reduction is rather rapid, and slow with solutions of about 20 percent concentra tion.
- the amounts of formic acid required may also vary. With 70 percent solutions of uranyl nitrate, one mole of formic acid is sufiicient to remove one mole of nitric acid. In 40 percent solutions, about 1 /2 moles of formic acid are generally employed for each mole of nitric acid in order to obtain optimum results; however, with equal molar concentrations of formic and nitric acids, it has been observed that at least percent of the plutonium is reduced. In 20 percent uranyl nitrate solutions, one mole of formic acid removes only about one-fifth mole of the nitric acid present in one hour under ordinary conditions of operation. In general, it
- Example I Formic acid was used as a reducing agent for plutonium in solutions of neutron irradiated uranyl nitrate. The experiments were carried out in glass to avoid possible reduction of the product. Starting solutions were prepared using uranyl nitrate hexahydrate made up to a 50 percent solution containing added nitric acid and oxidized plutonium (hexavalent plutonium).
- the amount of plutonium present was measured in each case by the number of alpha counts per minute per gram of uranyl nitrate hexahydrate as determined with a Geiger-Muller counter. In this solution, 97.8 percent of the plutonium was in the higher (above 4) oxidation state.
- the starting solution contained 50 percent uranyl nitrate and 5.5 percent nitric acid, the ratio of formic acid to nitric acid being 1.511; (2) the starting solution contained 50 percent uranyl nitrate and 1.38 percent nitric acid, the ratio of formic acid to nitric acid being 1.511; and (3) the starting solution contained 50 percent uranyl nitrate and 5.5 percent nitric acid, the ratio of formic acid to nitric acid being 0.375 :1.
- the formic acid was added at a constant rate below the surface of the boiling uranyl nitrate solution for a measured period of time. After the formic acid was added, the solutions were then boiled one hour. The results obtained appear in the table below:
- the solutions obtained from runs 2 and 3 were introduced into adsorption columns filled respectively with columbic oxide and Amberlite IR-l resin (a formaldehyde-sulphonated phenol condensation product) whereby the plutonium present in said solutions was adsorbed thereon and subsequently removed from the adsorbents by the use of a suitable eluting agent such as, for example, 1.25 N sodium bisulphate.
- a suitable eluting agent such as, for example, 1.25 N sodium bisulphate.
- formic acid may be used for the dual purpose of reducing plutonium in nitric acid solutions and destroying excess nitric acid present.
- the plutonium is reduced to a valent state not greater than 4 in which it may be readily removed by precipitation or adsorption, and the excess nitric acid which might interfere with precipitation and adsorption processes is destroyed.
- a process for separating plutonium values from nitric acid-containing solutions of hexavalent plutonium salts comprising treating said solutions with formic acid at elevated temperatures whereby plutonium is reduced to a valence state of not greater than +4 and the free nitric acid is destroyed and eliminated, and then recovering the plutonium from the solution thus treated.
- a process for separating plutonium values from nitric acid-containing solutions of hexavalent plutonium salts comprising treating said solutions with a mixture of formic acid and sulfuric acid at elevated temperature whereby plutonium is reduced to a valence state of not greater than +4 and the free nitric acid is destroyed and eliminated, and then recovering the plutonium from the solution thus treated.
- a process for separating plutonium values from nitric acid-containing solutions of hexavalent plutonium salts comprising treating said solutions with a mixture of formic acid and phosphoric acid at elevated temperature whereby plutonium is reduced to a valence state of not greater than +4 and the free nitric acid is destroyed and eliminated, and then recovering the plutonium from the solution thus treated.
- a process for separating plutonium values from nitric acid-containing solutions of hexavalent plutonium salts comprising treating said solutions at a temperature of from 75 to 98 C. with formic acid in quantities of from 1 to 1.5 moles of formic acid per one mole of nitric acid, whereby plutonium is reduced to a valence state of not greater than +4 and the free nitric acid is destroyed and eliminated, and then recovering the plutonium from the solution thus treated.
- a process for separating plutonium, uranium, and fission products the steps of treating a nitric acid solution containing salts of hexavalent plutonium, uranium, and of fission product elements with formic acid at an elevated temperature whereby plutonium is reduced to a valence state of not greater than +4 and the free nitric acid is destroyed and eliminated, and then recovering the plutonium from the solution thus treated.
- a process for separating plutonium from nitric acidcontaining solutions of hexavalent plutonium salts comprising treating said solutions With formic acid at an ele- 5 vated temperature whereby plutonium is reduced to a valence state of not greater than +4 and the free nitric acid is destroyed and eliminated, and then recovering the plutonium from the solution thus treated by adsorbing it with an ion exchange material.
- a process for separating plutonium from nitric acidcontaining solutions of hexavalent plutonium salts comprising treating said solutions with formic acid at an elevated temperature whereby plutonium is reduced to a acid is destroyed and eliminated, and then recovering the plutonium from the solution thus treated by precipitating it with a bismuth phosphate precipitate.
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Inorganic Compounds Of Heavy Metals (AREA)
Description
United States Patent CHEMICAL METHOD or TREATING FISSIONABLE MATERIAL Carl M. Olson, Richland, Wasln, assignor to the United States of America as represented by the United States Atomic Energy Commission No Drawing. Application April 4, 1945 Serial No. 586,619
8 Claims. (Cl. 23-145) This invention relates to an improvement in the process of preparing a pure fissionable element.
It is known that when uranium is subjected to neutron bombardment there is formed in small quantities a new element having an atomic weight of 239 and atomic number of 93, known as neptunium (symbol Np). This new element by radiactive decay is transformed through a half-life of 2.3 days to a further new element having an atomic weight of 239 and atomic number 94, known as plutonium (symbol Pu). Other isotopes of plutonium may also be formed. In addition certain other elements are formed as a result of fission of the uranium 235 nucleus such new elements being referred to as fission! fragments or, including radioactive decay products thereof, as fission products. The fission fragments include two general element groups, a light fission fragment group such as Br, Kr, Rb, Sr, Y, Zr, Cb, Mo, 43, Ru, and Rh, and a heavy fission fragment group such as Sb, Te, I, Xe, Cs, Ba, La, Ce, Pr and Nd. In radioactive decay many of the fission fragments form other short lived products. As a result, the radioactivity of the mass of uranium remains at a high and very dangerous level for some time following high density neutron bombardment. It is particularly desirable to separate the plutonium from the radioactive fission fragments and fission products, thereby removing from the mass sub jected to neutron bombardment the radioactive materials and particularly the light elements such as light metals having very short half-lives and consequently high radioactivities.
Following the bombardment of uranium with neutrons to produce new elements as discussed above, the usual procedure is to dissolve the entire mass in an acid solution such as nitric acid. This solution will then contain the uranium, plutonium, and all of the other products of the neutron bombardment including radioactive fission products.
It is generally necessary to use an excess of concentrated nitric acid in order to obtain a practical rate of solution of the uranium. After the neutron irradiated uranium metal has been dissolved, however, it has been found that the presence of an excess of nitric acid interferes with the recovery of plutonium. Thus, if plutonium is removed from solution by adsorption on organic adsorbents, the presence of excess concentrated nitric acid seriously reduces the efiiciency of the process and may even destroy the adsorbent.
In addition, the process of dissolving the bombarded uranium in concentrated nitric acid on a commercial scale oxidizes a substantial portion of the plutonium to its higher oxidation state. The most commonly used plutonium recovery method, namely by bismuth phosphate precipitation, does not work efliciently with plutonium in its higher state of oxidation or in the presence of excess nitric acid owing to the solubility of bismuth phosphate therein. Accordingly, it is necessary to both re- 2,902,340 Patented Sept. 1, 1959 move the excess nitric acid and reduce the plutonium to its lower valence state.
This excess of acid can be removed by neutralization with various bases but this introduces additional foreign ions into the solution. The deleterious effects of excess nitric acid can also be effectively avoided by lowering the concentration thereof to such an extent that it does not interfere with the recovery processes. Such dilution, however, is undesirable since it increases the total volume of material to be handled to an impractically large degree.
The oxidized plutonium can be reduced by means of a number of specific reducing agents such as ferrous ion, uranous ion, and the like. These reducing agents, however, introduce foreign elements that must themselves be removed before plutonium can be recovered in pure form.
It has now been discovered that the removal of excess nitric acid and the reduction of any oxidized plutonium present may be accomplished while avoiding the above mentioned difficulties. In accordance with the present invention, these objectives are attained by use of formic acid as a reducing agent. Formic acid is a reducing agent that is capable of reducing plutonium in its higher oxidation state to a valence state not greater than 4. In addition, the formic acid destroys excess nitric acid present by reacting with nitric acid probably in accordance with the following equation:
The use of formic acid to remove the excess nitric acid: is effective either when used in 20 percent uranyl nitrate solutions or in hot solutions as they come from the dis solver where the concentration is about 70 percent. The reaction is more rapid in the latter case and the rise inv temperature obtained thereby is desirable since complete reaction is insured, and the gases formed are eliminated? An additional advantage in adding formic acid to hot solutions in the dissolving vessel lies in the fact that such a vessel is normally equipped to handle the gases given off which might be objectionable at other points in the process.
When the neutron bombarded uranium is dissolved in nitric acid, usually a sutficient excess of concentrated nitric acid is used so as to give a solution containing about.70 percent uranyl nitrate. In its further treatment, the solution may be diluted to give a lower uranyl nitrate concentration, for example, 40 percent or 20 percent with corresponding decrease in nitric acid concentration.
The action of formic acid varies with the concentration of the solutions treated. With a concentration of 70 percent uranyl nitrate, the reduction proceeds vigorously; with 40 percent solutions, the reduction is rather rapid, and slow with solutions of about 20 percent concentra tion. The amounts of formic acid required may also vary. With 70 percent solutions of uranyl nitrate, one mole of formic acid is sufiicient to remove one mole of nitric acid. In 40 percent solutions, about 1 /2 moles of formic acid are generally employed for each mole of nitric acid in order to obtain optimum results; however, with equal molar concentrations of formic and nitric acids, it has been observed that at least percent of the plutonium is reduced. In 20 percent uranyl nitrate solutions, one mole of formic acid removes only about one-fifth mole of the nitric acid present in one hour under ordinary conditions of operation. In general, it
may be said that the less concentrated the solution is with respect to uranyl nitrate, the more formic acid required to elfect a satisfactory reduction of plutonium.
Other factors affecting the use of formic acid include the size of the reacting vessel, the depth of the solution, the degree of agitation, the temperature at which the reaction is carried out, and the presence or absence of sulfuric acid. The temperature effect is shown by tests where the use of 90 C. gave very rapid action and 75 C. gave moderate speed of reaction. In this connection it should be pointed out that in the recovery of plu tonium from solutions of the class contemplated in the present invention by methods involving the utilization of adsorbents, it has been discovered that this object can be best accomplished by maintaining the acidity of said solutions at a value of not more than about 0.5 N.
It has been found that the presence of sulfuric acid or phosphoric acid improves the efliciency of the process, particularly by making it run more rapidly. The theoretical explanation for the improvement owing to sulfuric acid is not definitely known. It has been observed, however, that the presence of sulfuric and phosphoric acid improves the overall yield of plutonium 011 precipitation.
The following example illustrates the process of the present invention and the relatively wide range of conditions that may be employed in obtaining substantially complete reduction of plutonium:
Example I Formic acid was used as a reducing agent for plutonium in solutions of neutron irradiated uranyl nitrate. The experiments were carried out in glass to avoid possible reduction of the product. Starting solutions were prepared using uranyl nitrate hexahydrate made up to a 50 percent solution containing added nitric acid and oxidized plutonium (hexavalent plutonium).
The amount of plutonium present was measured in each case by the number of alpha counts per minute per gram of uranyl nitrate hexahydrate as determined with a Geiger-Muller counter. In this solution, 97.8 percent of the plutonium was in the higher (above 4) oxidation state.
In these tests three conditions were selected: (1) the starting solution contained 50 percent uranyl nitrate and 5.5 percent nitric acid, the ratio of formic acid to nitric acid being 1.511; (2) the starting solution contained 50 percent uranyl nitrate and 1.38 percent nitric acid, the ratio of formic acid to nitric acid being 1.511; and (3) the starting solution contained 50 percent uranyl nitrate and 5.5 percent nitric acid, the ratio of formic acid to nitric acid being 0.375 :1. In all cases the formic acid was added at a constant rate below the surface of the boiling uranyl nitrate solution for a measured period of time. After the formic acid was added, the solutions were then boiled one hour. The results obtained appear in the table below:
Run Number 1 2 3 Percent Uranyl Nitrate 50 50 50 Plutonium Content in Alpha c.Im./g.l
Uranyl Nitrate Hexahydrate (97.8%
oxidized) 118. 5 118. 5 118. 5 HNO; Concentration in 50% Uranyl Nitrate Hexahydrate Solution, percent 5. 52 1. 38 5. 52 Excess Acidity Based on 20% Uranyl Nitrate Hexahydrate Solution 0. 4 N 1 N 0 4 N Plutonium in Valent State 014 or Below Present in Starting Solution, pereent. 4. 35 3. 75 4. 35 Moles HCO OH/mole HNO; 1. 5 l. 5 0. 375 Addition Time, hours 2 0. 5 0. 5 Supplementary Boiling, hours. 1 1 1 Percent Plutonium Reduced. 99. 4 99. 8 99. 6 Residual Acidity (HNO Based on 20% Uranyl N ltrate Hexahydrate Solution 0.03 N 0. 06 N 0. 34 N The first of these solutions, containing the reduced plutonium, was treated to remove plutonium by precipitation of bismuth phosphate as a carrier in accordance with the process described in United States application for Letters Patent of Glenn T. Seaborg et al., Serial No. 478,570, filed March 9, 1943 now Patent No. 2,799,553.
The solutions obtained from runs 2 and 3 were introduced into adsorption columns filled respectively with columbic oxide and Amberlite IR-l resin (a formaldehyde-sulphonated phenol condensation product) whereby the plutonium present in said solutions was adsorbed thereon and subsequently removed from the adsorbents by the use of a suitable eluting agent such as, for example, 1.25 N sodium bisulphate.
As pointed out above, it has been found in accordance with the present invention that formic acid may be used for the dual purpose of reducing plutonium in nitric acid solutions and destroying excess nitric acid present. Thus, by one simple operation and without the addition of undesirable foreign elements, the plutonium is reduced to a valent state not greater than 4 in which it may be readily removed by precipitation or adsorption, and the excess nitric acid which might interfere with precipitation and adsorption processes is destroyed.
It will be apparent to those skilled in the art that the process of the present invention is susceptible of numerous modifications without departing from the scope thereof. It is, therefore, to be strictly understood that any such modifications are to be regarded as lying within the scope of the present invention.
What is claimed is:
1. In a process for the recovery of plutonium values from an aqueous nitric acid solution containing hexavalent plutonium ions, the step which comprises treating said solution with formic acid whereby plutonium is reduced to a valence state of not greater than +4 and the free nitric acid is destroyed and eliminated.
2. A process for separating plutonium values from nitric acid-containing solutions of hexavalent plutonium salts, comprising treating said solutions with formic acid at elevated temperatures whereby plutonium is reduced to a valence state of not greater than +4 and the free nitric acid is destroyed and eliminated, and then recovering the plutonium from the solution thus treated.
3. A process for separating plutonium values from nitric acid-containing solutions of hexavalent plutonium salts, comprising treating said solutions with a mixture of formic acid and sulfuric acid at elevated temperature whereby plutonium is reduced to a valence state of not greater than +4 and the free nitric acid is destroyed and eliminated, and then recovering the plutonium from the solution thus treated.
4. A process for separating plutonium values from nitric acid-containing solutions of hexavalent plutonium salts, comprising treating said solutions with a mixture of formic acid and phosphoric acid at elevated temperature whereby plutonium is reduced to a valence state of not greater than +4 and the free nitric acid is destroyed and eliminated, and then recovering the plutonium from the solution thus treated.
5. A process for separating plutonium values from nitric acid-containing solutions of hexavalent plutonium salts, comprising treating said solutions at a temperature of from 75 to 98 C. with formic acid in quantities of from 1 to 1.5 moles of formic acid per one mole of nitric acid, whereby plutonium is reduced to a valence state of not greater than +4 and the free nitric acid is destroyed and eliminated, and then recovering the plutonium from the solution thus treated.
6. In a process for separating plutonium, uranium, and fission products, the steps of treating a nitric acid solution containing salts of hexavalent plutonium, uranium, and of fission product elements with formic acid at an elevated temperature whereby plutonium is reduced to a valence state of not greater than +4 and the free nitric acid is destroyed and eliminated, and then recovering the plutonium from the solution thus treated.
7. A process for separating plutonium from nitric acidcontaining solutions of hexavalent plutonium salts, comprising treating said solutions With formic acid at an ele- 5 vated temperature whereby plutonium is reduced to a valence state of not greater than +4 and the free nitric acid is destroyed and eliminated, and then recovering the plutonium from the solution thus treated by adsorbing it with an ion exchange material.
8. A process for separating plutonium from nitric acidcontaining solutions of hexavalent plutonium salts, comprising treating said solutions with formic acid at an elevated temperature whereby plutonium is reduced to a acid is destroyed and eliminated, and then recovering the plutonium from the solution thus treated by precipitating it with a bismuth phosphate precipitate.
References Cited in the file of this patent UNITED STATES PATENTS Thompson et a1. Mar. 19, 1957 OTHER REFERENCES Mellor: Inorganic and Theoretical Chemistry, vol. 8, pages 588-9, Longmans, London (1928).
Seaborg et al.: The Actinide Elements, pp. 256, 297 (1954). Publ. by McGraW-Hill Book Co., NY. (August valence state of not greater than +4 and the free nitric 15 15, 1944, date indicated in reference No. 75, page 297.)
Claims (1)
1. IN A PROCESS FOR THE RECOVERY OF PLUTONIUM VALUES FROM AN AQUEOUS NITRIC ACID SOLUTION CONTAINING HEXAVALENT PLUTONIUM IONS, THE STEP WHICH COMPRISES TREATING SAID SOLUTION WITH FORMIC ACID WHEREBY PLUTONIUM IS REDUCED TO A VALENCE STATE OF NOT GREATER THAN +4 AND THE FREE NITRIC ACID IS DESTROYED AND ELIMINTED.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US586619A US2902340A (en) | 1945-04-04 | 1945-04-04 | Chemical method of treating fissionable material |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
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| US586619A US2902340A (en) | 1945-04-04 | 1945-04-04 | Chemical method of treating fissionable material |
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| US2902340A true US2902340A (en) | 1959-09-01 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3673086A (en) * | 1969-07-11 | 1972-06-27 | Kernforschung Gmbh Ges Fuer | Method of removing nitric acid, nitrate ions and nitrite ions out of aqueous waste solutions |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2785951A (en) * | 1944-01-26 | 1957-03-19 | Stanley G Thompson | Bismuth phosphate process for the separation of plutonium from aqueous solutions |
-
1945
- 1945-04-04 US US586619A patent/US2902340A/en not_active Expired - Lifetime
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2785951A (en) * | 1944-01-26 | 1957-03-19 | Stanley G Thompson | Bismuth phosphate process for the separation of plutonium from aqueous solutions |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3673086A (en) * | 1969-07-11 | 1972-06-27 | Kernforschung Gmbh Ges Fuer | Method of removing nitric acid, nitrate ions and nitrite ions out of aqueous waste solutions |
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