US3891741A
Expired / Lapsed
US
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Recovery of fission products from acidic waste solutions thereof
Assignee: PPG Industries Inc
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Filing: 1972-11-24
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Granted: 1975-06-24
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Expires: 1992-11-24
Abstract
Abstract Fission products, e.g., palladium, ruthenium and technetium, are removed from aqueous, acidic waste solutions thereof. The acidic waste solution is electrolyzed in an electrolytic cell under controlled cathodic potential conditions and technetium, ruthenium, palladium and rhodium deposited on the cathode. Metal deposit is removed from the cathode and dissolved in acid. Acid insoluble rhodium metal is recovered, dissolved by alkali metal bisulfate fusion and purified by electrolysis. In one embodiment, the solution formed by acid dissolution of the cathode metal deposit is treated with a strong oxidizing agent and distilled to separate technetium and ruthenium (as a distillate) from palladium. Technetium is separated from ruthenium by organic solvent extraction and then recovered, e.g., as an ammonium salt. Ruthenium is disposed of as waste by-product. Palladium is recovered by electrolysis of an acid solution thereof under controlled cathodic potential conditions. Further embodiments wherein alternate metal recovery sequences are used are described.
Inventors
- 👤 William W Carlin
- 👤 William B Darlington
- 👤 Donald W Dubois
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 01:49
CPC Classifications
G; G21; G21F; G21F9/00; G21F9/007; C; C01; C01G; C01G55/00; C01G99/00; C01G99/006; C25; C25C; C25C1/00
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
106 words
A PROCESS FOR SEPARATING RHODIUM. PALLADIUM AND TECHNETIUM FROM AQUEOUS, ACIDIC SOLUTIONS CONTAINING SAID METAL VALUES AND OTHER FISSION PRODUCT METAL VALUES SAID SOLUTION RESULTING FROM PROCESSING IRRADIATED NUCLEAR FUEL, WHICH COMPRISES ELECTROLYZING SIAD SOLUTION HAVING AN ACID CONCENTRATION NO GREATER THAN ABOUT 1 MOLAR IN AN ELEECTROYLTIC CELL UNDER CONTROLLED CATHODIC POTENTIAL CONDITIONS AND AT A POTENTIAL AT WHICH RHODIUM, PALLADIUM AND TECHNETIUM ARE DEPOSITED ON THE CATHODE OF THE CELL, REMOVING METAL DELETED WASTE SOLUTION FROM THE CELL, DISSOLVING METAL DEPOSITED ON THE CATHODE IN STRONG ACID TO PROVIDE AN ACID SOLUTION OF DEPOSITED METAL VALUES, AND SEPARATING UNDISSOLVED RHODIUM METAL FROM THE SOLUTION.
Claim 2
Dependent Claim
106 words
A PROCESS FOR SEPARATING RHODIUM. PALLADIUM AND TECHNETIUM FROM AQUEOUS, ACIDIC SOLUTIONS CONTAINING SAID METAL VALUES AND OTHER FISSION PRODUCT METAL VALUES SAID SOLUTION RESULTING FROM PROCESSING IRRADIATED NUCLEAR FUEL, WHICH COMPRISES ELECTROLYZING SIAD SOLUTION HAVING AN ACID CONCENTRATION NO GREATER THAN ABOUT 1 MOLAR IN AN ELEECTROYLTIC CELL UNDER CONTROLLED CATHODIC POTENTIAL CONDITIONS AND AT A POTENTIAL AT WHICH RHODIUM, PALLADIUM AND TECHNETIUM ARE DEPOSITED ON THE CATHODE OF THE CELL, REMOVING METAL DELETED WASTE SOLUTION FROM THE CELL, DISSOLVING METAL DEPOSITED ON THE CATHODE IN STRONG ACID TO PROVIDE AN ACID SOLUTION OF DEPOSITED METAL VALUES, AND SEPARATING UNDISSOLVED RHODIUM METAL FROM THE SOLUTION.
Claim 3
Dependent Claim
16 words
The process of claim 1 wherein the acid waste solution is a Purex acid waste stream.
Claim 4
Dependent Claim
18 words
The process of claim 1 wherein the waste solution is filtered before electrolysis to remove undissolved rhodium therefrom.
Claim 5
Dependent Claim
28 words
The process of claim 1 wherein the waste solution is electrolyzed at a potential of at least -0.1 volts with reference to a standard silver/silver chloride reference electrode.
Claim 6
Dependent Claim
23 words
The process of claim 1 wherein the acid concentration of the waste solution electrolyzed is from about 0.25 molar to about 1 molar.
Claim 7
Dependent Claim
58 words
The process of claim 1 wherein undissolved rhodium metal is dissolved by fusion with alkali metal bisulfate selected from the group consisting of sodium and potassium bisulfate, and an aqueous solution of the fused product is electrolyzed in an electrolytic cell under controlled cathodic potential conditions and at a potential at which rhodium is deposited on the cathode.
Claim 8
Dependent Claim
31 words
The process of claim 6 wherein the aqueous solution is electrolyzed at a potential of from about -0.05 to about -0.5 volts with reference to a standard silver/silver chloride reference electrode.
Claim 9
Dependent Claim
81 words
The process of claim 1 wherein a strong oxidizing agent is added to the acid solution of deposited metal values in amounts sufficient to oxidize technetium and ruthenium present in said acid solution to their respective volatile oxides, the resulting solution is distilled to provide a technetium containing distillate and a palladium containing bottoms, and the distillate is electrolyzed in an electrolytic cell under controlled cathodic potential conditions and at a potential at which technetium metal is deposited on the cathode.
Claim 10
Dependent Claim
41 words
The process of claim 8 wherein the palladium containing bottoms is electrolyzed in an electrolytic cell under controlled cathodic potential conditions and at a potential at which palladium is deposited on the cathode and palladium metal is recovered from the cathode.
Claim 11
Dependent Claim
61 words
The process of claim 8 wherein technetium metal deposited on the cathode is dissolVed in strong mineral acid to form an acid solution of technetium values, the acid solution is made alkaline with an alkaline reagent, technetium values are extracted from the alkaline solution with an organic solvent having affinity for technetium and technetium values are separated from the organic solvent.
Claim 12
Dependent Claim
16 words
The process of claim 10 wherein the organic solvent is pyridine or dimethyl substituted pyridine derivatives.
Claim 13
Dependent Claim
36 words
The process of claim 10 wherein the organic solvent is steam distilled to provide an aqueous solution containing technetium values and ammoniacal reagent is added to the aqueous solution in amounts sufficient to form ammonium pertechnetate.
Claim 14
Dependent Claim
47 words
The process of claim 1 wherein the acid solution of deposited metal values is made alkaline with alkaline reagent and the resuting alkaline aqueous solution is contacted intimately with organic solvent having affinity for technetium to form an organic phase containing technetium values and an aqueous phase.
Claim 15
Dependent Claim
37 words
The process of claim 13 wherein the organic phase is steam distilled to produce an aqueous solution containing technetium values and an ammoniacal reagent is added to the aqueous solution in amounts sufficient to form ammonium pertechnetate.
Claim 16
Dependent Claim
35 words
The process of claim 14 wherein ammonium pertechnetate is crystallized from the aqueous solution and hydrogen chloride added to the mother liquor in amounts sufficient to precipitate palladium values contained therein as the salt, dichlorodiamminepalladium(II)
Claim 17
Dependent Claim
97 words
The process of claim 13 wherein the organic phase is steam distilled to produce an aqueous solution containing technetium and palladium values, mineral acid is added to the aqueous solution in amounts sufficient to provide an acidic aqueous solution having an acid concentration of not greater than about 1 molar, and the acidic aqueous solution is electrolyzed in an electrolytic cell under controlled cathodic potential conditions and at a potential sufficiently negative to deposit palladium on the cathode but sufficiently positive with respect to the potential at which technetium is deposited to thereby retain technetium in solution.
Claim 18
Dependent Claim
30 words
The process of claim 16 wherein the palladium depleted aqueous solution is treated with ammoniacal reagent in amounts sufficient to form ammonium pertechnetate and ammonium pertechnetate crystallized from the solution.
Claim 19
Dependent Claim
55 words
The process of claim 1 wherein the acid solution of deposited metal values is electrolyzed in an electrolytic cell under controlled cathodic potential conditions and at a potential sufficiently negative to deposit palladium on the cathode but sufficiently positive with respect to the potential at which technetium is deposited to thereby retain technetium in solution.
Claim 20
Dependent Claim
20 words
The process of claim 18 wherein the acid solution electrolyzed has an acid concentration not greater than about 1 molar.
Claim 21
Dependent Claim
69 words
The process of claim 18 wherein the palladium depleted solution is made alkaline with alkaline reagent, the alkaline solution intimately contacted with organic solvent having affinity for technetium to form an organic phase containing technetium and an aqueous phase, the organic phase is steam distilled to produce an aqueous solution containing technetium values and the aqueous solution is treated with ammoniacal reagent in amounts sufficient to form ammonium pertechnetate.
Claim 22
Dependent Claim
102 words
A process for separating rhodium values from aqueous acidic solutions containing said metal values and other fission product metal values, said solution resulting from processing irradiated nuclear fuel, which comprises electrolyzing said solution having an acid concentration no greater than about 4 molar in an electrolytic cell under controlled cathodic potential conditions and at a potential of from about -0.05 to about -0.5 volts with reference to a standard silver/silver chloride reference electrode, removing metal depleted waste solution from the cell, dissolving acid soluble metal deposited on the cathode in strong aciD and separating undissolved rhodium metal from the resulting acid solution.
Claim 23
Dependent Claim
102 words
A process for separating rhodium values from aqueous acidic solutions containing said metal values and other fission product metal values, said solution resulting from processing irradiated nuclear fuel, which comprises electrolyzing said solution having an acid concentration no greater than about 4 molar in an electrolytic cell under controlled cathodic potential conditions and at a potential of from about -0.05 to about -0.5 volts with reference to a standard silver/silver chloride reference electrode, removing metal depleted waste solution from the cell, dissolving acid soluble metal deposited on the cathode in strong aciD and separating undissolved rhodium metal from the resulting acid solution.
Claim 24
Dependent Claim
88 words
A process for separating palladium values from aqueous acidic solutions containing said metal values and other fission product metal values, said solution resulting from processing irradiated nuclear fuel, which comprises electrolyzing said solution having an acid concentration no greater than about 4 molar in an electrolytic cell under controlled cathodic potential conditions and at a potential of from about +0.1 to about -0.05 volts with reference to a standard silver/silver chloride reference electrode, removing metal depleted waste solution from the cell and removing palladium deposits from the cathode.
Claim 25
Dependent Claim
88 words
A process for separating palladium values from aqueous acidic solutions containing said metal values and other fission product metal values, said solution resulting from processing irradiated nuclear fuel, which comprises electrolyzing said solution having an acid concentration no greater than about 4 molar in an electrolytic cell under controlled cathodic potential conditions and at a potential of from about +0.1 to about -0.05 volts with reference to a standard silver/silver chloride reference electrode, removing metal depleted waste solution from the cell and removing palladium deposits from the cathode.
Claim 26
Dependent Claim
88 words
A process for separating technetium values from aqueous, acidic solutions containing said metal values and other fission product metal values, said solution resulting from processing irradiated nuclear fuel, which comprises electrolyzing said solution having an acid concentration no greater than about 1 molar in an electrolytic cell under controlled cathodic potential conditions and at a potential of from about -0.3 to about -0.5 volts with reference to a standard silver/silver chloride reference electrode, removing metal depleted waste solution from the cell and removing technetium deposits from the cathode.
Claim 27
Dependent Claim
88 words
A process for separating technetium values from aqueous, acidic solutions containing said metal values and other fission product metal values, said solution resulting from processing irradiated nuclear fuel, which comprises electrolyzing said solution having an acid concentration no greater than about 1 molar in an electrolytic cell under controlled cathodic potential conditions and at a potential of from about -0.3 to about -0.5 volts with reference to a standard silver/silver chloride reference electrode, removing metal depleted waste solution from the cell and removing technetium deposits from the cathode.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-06-23 | 1978-12-23 | 1979-06-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-06-23 | 1982-12-23 | 1983-06-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-06-23 | 1986-12-23 | 1987-06-24 | $7700.00 | Window Closed / Lapsed |