Uranium recovery using electrolysis

Abstract

An electrolytic process for recovering uranium produces high quality uranium while reducing the processing necessary as well as the chemicals consumed. The process is environmentally friendly as it significantly reduces the emission of carbon dioxide from the processing system.

1 . A method for recovering uranium comprising:
 passing a solution containing soluble uranium and basic salt consisting of at least one of the group consisting of alkali metal carbonate and alkali metal bicarbonate into the anode chamber of an electrolytic cell, said electrolytic cell comprising an anode chamber, a cathode chamber, and an ion-permeable membrane therebetween so as to selectively isolate the anode chamber from the cathode chamber;   passing a catholyte into the cathode chamber of the electrolytic cell; and   operating the electrolytic cell so as to produce carbon dioxide gas from the anode chamber, transfer alkali metal ions through the ion-permeable membrane from the anode chamber to the cathode chamber, produce a solution containing soluble uranium and being substantially free of alkali metal and carbonate/bicarbonate ions from the anode chamber; and producing a alkali metal hydroxide solution from the cathode chamber.   
   
   
       2 . The method of  claim 1 , wherein the method further comprises precipitating the uranium from the solution containing soluble uranium to produce uranium which is substantially free of alkali metal. 
   
   
       3 . The method of  claim 2 , wherein the method comprises precipitating the uranium with at least one of the group consisting of hydrogen peroxide and ammonia. 
   
   
       4 . The method of  claim 1 , wherein the method further comprises producing a hydrogen gas from the cathode chamber of the electrolytic cell and mixing the hydrogen gas with the solution containing soluble uranium to thereby precipitate the uranium. 
   
   
       5 . The method of  claim 1 , wherein the method further comprises contacting the carbon dioxide gas with the alkali metal hydroxide solution produced by the electrolytic cell to form an alkali metal carbonate solution. 
   
   
       6 . The method of  claim 5 , wherein the method further comprises utilizing the alkali metal carbonate solution to extract soluble uranium in a solvent extractor and passing said solution of alkali metal carbonate and soluble uranium into the electrolytic cell to thereby recycle the alkali metal carbonate. 
   
   
       7 . The method of  claim 6 , wherein the method comprises passing a solution containing acid and soluble uranium through a solvent extractor to thereby transfer the soluble uranium to said solution of alkali metal carbonate. 
   
   
       8 . The method of  claim 7 , wherein the method comprises utilizing an ion-exchange resin to concentrate the soluble uranium. 
   
   
       9 . A method for recovering uranium comprising:
 selecting a first solution containing soluble uranium;   passing the first solution containing soluble uranium through a solvent extractor to thereby transfer the soluble uranium into a second alkali metal salt solution comprising at least one of the group consisting of alkali metal carbonate and alkali metal bicarbonate to thereby generate a third alkali metal salt solution containing soluble uranium;   passing the third alkali metal salt solution having soluble uranium into an electrolytic cell to thereby remove the alkali metal carbonate or alkali metal bicarbonate from the alkali metal salt solution to produce a fourth solution containing soluble uranium; and   precipitating the soluble uranium from the fourth solution of soluble uranium.   
   
   
       10 . The method of  claim 9 , wherein the method further comprises using a mixture of kerosene and D2EHPA/TOPO as an extraction solvent to transfer the soluble uranium from the first solution to the second alkali metal salt solution. 
   
   
       11 . The method of  claim 9 , wherein the method further comprises passing the first solution through an ion-exchange resin to generate a solution having a higher concentration of uranium and passing said solution of higher concentration through said solvent extractor. 
   
   
       12 . The method of  claim 9 , wherein the method further comprises, in the electrolytic cell, passing the third solution having alkali metal salt and soluble uranium into the anode chamber of the cell, electrolyticaly converting the alkali metal salt to alkali metal ions and carbon dioxide gas, passing the alkali metal ions through an ion-permeable membrane into the cathode chamber; and producing from the anode chamber said fourth solution containing soluble uranium and having a significantly reduced concentration of alkali metal salt. 
   
   
       13 . The method of  claim 10 , wherein the fourth solution is substantially free of alkali metal salt. 
   
   
       14 . The method of  claim 10 , wherein the method further comprises, in the electrolytic cell, passing an aqueous catholyte solution into the cathode chamber, electrolyticaly converting water to hydrogen gas and hydroxide ions so as to form a alkali metal hydroxide solution, and producing from the cathode chamber, said alkali metal hydroxide solution. 
   
   
       15 . The method of  claim 14 , wherein the method further comprises mixing the carbon dioxide and alkali metal hydroxide solution produced in the electrolytic cell to thereby produce an alkali metal carbonate solution. 
   
   
       16 . The method of  claim 15 , wherein the method further comprises passing the carbon dioxide and alkali metal hydroxide solution through a scrubber to thereby for the alkali metal carbonate solution. 
   
   
       17 . The method of  claim 15 , wherein the method further comprises passing the alkali metal carbonate solution through the solvent extractor to receive soluble uranium and thereby form the third solution containing alkali metal carbonate and soluble uranium. 
   
   
       18 . The method of  claim 12 , wherein the method further comprises adding sulfate ions to the third solution. 
   
   
       19 . The method of  claim 9 , wherein the method further comprises precipitating the soluble uranium with at least one of the group consisting of ammonia and hydrogen peroxide. 
   
   
       20 . A method for recovering uranium comprising:
 selecting an acid solution containing soluble uranium;   passing the acid and uranium through a solvent extractor to thereby transfer the uranium to a solution of sodium carbonate;   passing the solution of sodium carbonate and uranium through an electrolytic cell to thereby remove the sodium carbonate from the sodium carbonate and uranium solution to produce a uranium solution substantially free of sodium carbonate; and   precipitating and collecting the uranium.   
   
   
       21 . The method of  claim 20 , wherein the method further comprises passing the acid solution through an ion-exchange resin to thereby adsorb the uranium onto the resin;
 passing a strong acid stripping solution through the ion-exchange resin to thereby desorb the uranium and create a solution of strong acid and uranium which has a higher concentration of uranium than the leach solution;   passing the solution of strong acid and uranium through the solvent extractor.   
   
   
       22 . The method of  claim 20 , wherein the method further comprises selecting a leach solution which is an acidic solution containing soluble uranium. 
   
   
       23 . The method of  claim 20 , wherein the method further comprises passing the leach solution through a first packed column of ion-exchange resin to load the first packed column while passing the strong sulfuric acid stripping solution through a second packed column which has been previously loaded with uranium to thereby remove the uranium. 
   
   
       24 . The method of  claim 23 , wherein the method comprises selective alternating, for a plurality of packed columns, between loading a packed column with uranium contained in the leach solution and unloading another packed column of uranium via the stripping solution to thereby allow for substantially continuous flow of the leach solution stripping solution through the plurality of packed columns. 
   
   
       25 . The method of  claim 20 , wherein the method further comprises utilizing a mixture of kerosene and D2EHPA/TOPO in the solvent extractor to extract the uranium from the sulfuric acid stripping solution and using the sodium carbonate solution to extract the uranium from the kerosene mixture. 
   
   
       26 . The method of  claim 20 , wherein the method further comprises, in an anode chamber of the electrolytic cell, removing the sodium carbonate from the sodium carbonate and uranium solution, generating carbon dioxide gas, and releasing a uranium solution which is substantially free of sodium carbonate, transferring sodium ions through the ion-permeable membrane from the anode chamber to a cathode chamber of the electrolytic cell, and, in the cathode chamber, generating hydrogen gas, producing hydroxide ions to thereby produce a sodium hydroxide solution, and releasing a sodium hydroxide solution. 
   
   
       27 . The method of  claim 26 , wherein the method further comprises mixing the carbon dioxide gas from the anode chamber and the sodium hydroxide solution from the cathode chamber to thereby form a sodium carbonate solution. 
   
   
       28 . The method of  claim 27 , wherein the method further comprises using the sodium carbonate solution formed from the electrolytic cell products as the feed solution of sodium carbonate to the solvent extractor to thereby recycle the sodium carbonate. 
   
   
       29 . The method of  claim 20 , wherein the method further comprises precipitating the uranium with one of the group consisting of hydrogen peroxide and ammonia and calcining the uranium to form uranium oxide.