Abstract:
The invention relates to a method for recovering products from the defluorination of uranium hexafluoride. Recovered are a commercial grade anhydrous hydrogen fluoride and triuranium oxide through the use of two distinct reactors.

Description:
The present invention relates generally to a method for recovering products from the defluorination of uranium hexafluoride. More particularly, the present invention relates to the recovery of commercial grade liquid anhydrous hydrogen fluoride and water insoluble stable triuranium octoxide. 
     BACKGROUND OF THE INVENTION 
     Commercially useful uranium isotopes such as U 235  have been produced in well known processes for over 40 years. The feed material for these processes have been produced from a uranium hexafluoride (UF6) enrichment process which takes natural uranium, which contains 0.7% U 235 , to suitable levels for nuclear fuel. The enrichment process leaves behind a UF 6  material that contains mostly U 238  and 0.1-0.3% U 235 . The material is referred to as depleted UF 6  (DUF 6 ) and as of yet has little commercial value although there is hope in the future that new enrichment technologies will allow for more of the U 235  to be removed from the DUF 6  essentially turning it into a resource. 
     The DUF 6  that has been produced for the last 40 years is stored in carbon steel cylinders and amounts to around 50,000 cylinders or over 1 billion pounds of material. Storage of these cylinders is not considered a long term solution because of the potential for corrosion to the cylinders which could cause a release of the material into the environment. UF 6  reacts readily with the moisture in the air to form hydrofluoric acid and water soluble uranyl fluoride (UO 2 F 2 ). It is looked upon as a potential safety and environmental hazard. It is therefore desirable to have a cost effective process which can convert the DUF 6  into its most stable insoluble form uranium oxide (U 3 O 8 ). In addition, the process will create virtually no waste while recovering the hydrogen fluoride (HF) values of the DUF 6 . 
     While others have practiced the chemical equations mentioned in the present invention, (U.S. Pat. No. 5,346,648) no one has succeeded in putting together a complete process, or achieved the objectives of the present invention in the manner in which those objectives are achieved by the present invention. The present invention has fulfilled a long felt need for recovering commercially useful anhydrous hydrogen fluoride (AHF) from uranium hexafluoride (UF 6 ). Furthermore the method of the present invention produces a stable insoluble uranium oxide, U 3 O 8 , that is less toxic than UF 6  and can be stored for future use, disposed of in a low radiation level burial site at minimal cost, or used in current shielding applications. 
     While the method in U.S. Pat. No. 5,346,648 appears similar to the present invention, the present invention uses a liquid phase first reactor. Because of this it has numerous advantages over its predecessor. The present invention can be run at low temperatures and pressures. It can therefore use less expensive materials of construction than the super alloys required to withstand the high temperatures described in U.S. Pat. No. 5,346,648. The present invention is easier to control than its predecessor by nature of maintaining water in excess. The only feeds to the process are UF 6  vapor and a small water makeup stream in the form of aqueous HF that is mixed into the internal recycle stream. It is safer to run than the method of U.S. Pat. No. 5,346,648 because it is run at low temperatures and pressures. Still another improvement is the intermediate uranyl fluoride hydrate that is made in present invention&#39;s liquid phase reactor which is different than the uranyl fluoride intermediate made in its predecessor. Many other improvements exist and are realized. 
     SUMMARY OF THE INVENTION 
     The present invention is a method for recovering two distinct and separable products from the defluorination of uranium hexafluoride. The first product is a commercial grade liquid anhydrous hydrogen fluoride (AHF). The second is water insoluble uranium oxide such as uranium dioxide (UO 2 ), uranium trioxide (UO 3 ) and preferably, stable triuranium octoxide (U 3 O 8 ) which can be stored safely for future use or disposed of in a conventional manner. A liquid recycle stream consisting of the azeotrope of water and hydrogen fluoride also exists and is used as a feed stock to the primary and or secondary reactor. The present method produces a commercially valuable material while reducing the amount of hazardous material that needs to be stored or disposed of in addition to making it less of a safety and environmental concern. 
     The method includes a primary reactor which is a reservoir, pump tank/settler/vaporizer around which a stream of an aqueous hydrogen fluoride solution circulates. A gaseous stream of uranium hexafluoride (UF 6 ) is introduced into the circulating solution. The UF 6  reacts with some of the excess water in the circulating stream producing a uranyl fluoride intermediate (UO 2 F 2 .H 2 O) and HF which dissolve in the solution. When the resulting solution has been saturated with UO 2 F 2 .H 2 O solid, the uranyl fluoride intermediate begins to precipitate out of solution and settles out at the bottom of the pump tank (settler). As water is reacted away and HF is evolved the resulting solution becomes more and more concentrated in HF and the resulting vapor is high in HF concentration. By controlling the temperature of the solution in the pump tank, HF rich vapor and water vapor essentially free of uranium can be condensed and fed into a conventional distillation column. 
     The solid uranyl fluoride intermediate produced is fed to a secondary reactor and reacted with water vapor to produce a uranium oxide product such as triuranium octoxide product and a gaseous mixture of water, hydrogen fluoride, and oxygen. This gaseous mixture is combined with the gaseous mixture of water and hydrogen fluoride from the primary reactor, condensed and subsequently fed into the conventional distillation column. The components are separated in a distillation column to obtain a commercial grade anhydrous hydrogen fluoride product stream overhead and an aqueous azeotropic recycle stream containing water and hydrogen fluoride. The azeotrope composition recycle stream is returned in part or in its entirety to the primary reactor as a water makeup to the system. The recycle stream can also be vaporized and combined with a small amount of makeup steam and used as a water feed source to the second reactor. 
     Hydrogen gas may be used in place of water as a feed to the secondary reactor with the resulting stream of HF and hydrogen 
     
       
         UO 2 F 2 .H 2 O+H 2 →U 3 O 8 +HF+H 2   
       
     
     gas (small amount) being combined with the HF rich vapor from the primary reactor, condensed and fed into the conventional distillation column. In this case makeup water will need to be fed to the primary reactor. 
     A third reactor may be added that would act as a fluoride stripper for soluble fluorine in the triuranium octoxide product. Solid triuranium octoxide material is fed to the reactor and contacted with steam. If the third reactor is added any makeup water that is needed for the entire system is fed to it. The resulting mixture of steam with a very slight amount of HF is fed directly into the second reactor or should a hydrogen feed be selected as a reactant in the second reactor the steam and HF mixture would be condensed and fed to the primary reactor as makeup water. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a schematic flowchart of the method of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to FIG. 1, the units of operation include a first reactor  1 , a circulation pump  2 , a pump/settling tank/vaporizer  3 , a second reactor  4 , a fluorine stripper  5 , a separation unit  6 , two condensers  7   a  and  7   b , two vaporizers  8   a  and  8   b , and a transfer pump  9 . The material streams defined by the method are designated  10 - 25  and are further described with reference thereto. The pump/settling tank  3  is initially charged with a liquid hydrogen fluoride (HF) and water solution in the range of 37% to 65% HF. The solution is circulated around a closed loop (stream  10 ) through the first reactor  1 . The solution is initially heated by an external source in pump/settling tank  3  close to its boiling point. The actual temperature depends on the concentration of HF in the solution, but in the range of 78-115° C. Feed stream  11 , comprised of gaseous uranium hexafluoride (UF 6 ), is fed into the first reactor  1  and contacts stream  10 . The UF 6  reacts with some of the excess water in circulating stream  10  to produce a uranyl fluoride hydrate (UO 2 F 2 .H 2 O) intermediate and HF which initially dissolve in the solution by the following reaction equation (1): 
     
       
         UF 6 +2H 2 O→UO 2 F 2 . H 2 O (s) +4HF 
       
     
     As the UF 6  feed process continues the HF content of the solution increases and the solubility limit of UO 2 F 2 .H 2 O is reached and solid UO 2 F 2 .H 2 O precipitates out of solution and settles to the bottom of pump/settling tank  3 . As water is reacted away and HF is evolved the concentration of HF in the solution increases and the solution will begin to boil producing a HF rich vapor stream  12  comprised of between a ratio of 37.7/62.3% HF/water and make up stream  14  up to &gt;98/&lt;2% HF/water depending on the vapor/liquid equilibrium of the HF solution at its boiling point. 
     First reactor  1  and pump/settling tank  3  are kept at a pressure of 1-5 psig and a temperature dependent on the boiling point of the HF solution contained therein. The temperature is set thereby controlling the composition of vapor stream  12 . The solubility of UO 2 F 2 .H 2 O is dependent upon the concentration of HF in the solution. 6.6 weight % UO 2 F 2 .H 2 O was the observed solubility in a solution containing 38.22% HF at ambient temperature and 4.34 weight % UO 2 F 2 .H 2 O was found to be soluble in a 52.4% HF solution at ambient temperature. 
     Two outlet streams  12  and  13  are recovered separately from the pump/settling tank  3 . Stream  13  is comprised of a slurry of solid UO 2 F 2 .H 2 O and HF/water/ UO 2 F 2 .H 2 O solution that is fed into second reactor  4 . The HF and water in the stream are boiled off as it enters the hot second reactor essentially drying the solids. Some reaction does occur between the water and UO 2 F 2 , but it is incomplete so steam (stream  20 ) is also fed to second reactor  4  in a stoichiometric excess to the amount of UO 2 F 2 .H 2 O in stream  13  and preferably at an excess of from about 200 to 500%. The steam finishes the reaction of the UO 2 F 2 .H 2 O in second reactor  4  which is maintained at a temperature of 427-704° C. and preferably between 538 and 649° C. Second reactor  4  is maintained at a pressure between about 0-5 psig and preferably between about 2-4 psig. 
     The reaction products of water and uranyl fluoride leave second reactor  4  separately as stream  24  and  25  which are characterized by the following generalized reaction equation (2): 
     
       
         3UO 2 F 2 +3H 2 O→U 3 O 8(s) +6HF+0.5O 2   (2) 
       
     
     As indicated by equation (2), outlet stream  25  comprises solid triuranium octoxide (U 3 O 8 ) product with a less than 200 ppm soluble (unreacted) fluoride content and outlet stream  24  comprises a gaseous mixture of water, HF, and oxygen. The U 3 O 8  of stream  25  is fed to a fluorine stripper  5  if it does not meet the specification for concentration of soluble fluorides. Water fed into vaporizer  8   a  is turned into steam (stream  23 ) and is fed into fluorine stripper  5  in a large stoichiometric excess from about 200 to 500% of the amount of UO 2 F 2 .H 2 O in stream  25 . Two separate outlet streams,  20  and  22 , leave fluoride stripper  5 . Product stream  22  comprises triuranium octoxide product with a less than 25 ppm soluble fluoride concentration and is isolated from the process for storage or disposal. Stream  20 , comprised of essentially steam, becomes a feed stream to second reactor  4 . If fluorine stripper  5  is not necessary stream  23  and stream  20  are the same, as are stream  25  and  22 . 
     As a variation, stream  13  is reacted with hydrogen gas instead of steam or HF/water azeotrope as a water source in second reactor  4 . Stream  20  becomes hydrogen. In that case the outlet streams  24  and  25  are characterized by the generalized equations (3) and (4). 
      2UO 2 F 2 +2H 2(excess) →2UO 2 +4HF+2H 2 O+H 2(excess)   (3) 
     
       
         3UO 2 +O 2 →U 3 O 8   (4) 
       
     
     Outlet stream  25 , comprised of UO 2  is unstable at elevated temperatures and reacts to the triuranium octoxide when exposed to air after second reactor  4 . If hydrogen is used as the feed and the fluorine stripper  5  is necessary then the stream outlet of fluorine stripper  5  goes to pump/settling tank  3  as the water makeup for the system. 
     First reactor  1  and second reactor  4  outlet streams  12  and  24  respectively are combined before condenser  7   a  to form stream  19  comprised of a gaseous mixture of HF/water/oxygen and in some cases H 2 . Stream  19  is cooled as it passes through condenser  7   a  and depending on the temperature and pressure conditions of stream  19  it may be entirely in a liquid state, but more than likely it will be in two states, a gaseous state comprised mainly of oxygen and a liquid state comprised of HF and water. Stream  19  becomes a feed to separation unit  6 . It is further understood that streams  12  and  24  may not be combined before separation unit  6 , but may be mixed inside separation unit  6  internally without the use of condenser  7   a.    
     Regardless, separation unit  6  is a distillation column wherein stream  19  is separated into two separate streams  15  and  16 . Stream  16  is a gaseous mixture of HF and oxygen essentially free of water and uranium. Outlet stream  16  is subsequently fed to condenser  7   b  from which a gaseous stream  17  comprised essentially of oxygen, which will be vented to a scrubber and a liquid stream  18  composed of commercial grade anhydrous hydrogen fluoride with less than 1 ppm uranium and less than 500 ppm water which is packaged for transfer to customer end use. Outlet stream  15  is a liquid stream comprised of about 37% HF and about 63% water which is the azeotrope composition of HF/water and is used in its entirety or in part as recycle feed to first reactor  1  and second reactor  4 . Transfer pump  9  moves stream  15  after which stream  15  is split into recycle streams  14  and  21 . Stream  14  is recycled as a liquid to first reactor  1  to keep a constant level and desired HF concentration in first reactor  1 . Stream  21  is vaporized and recycled back and used as a substitute or supplement to feed stream  20  into second reactor  4 . After the recycle streams  14  and  21  are going the amount of water makeup to the entire system in the form of stream  23  is adjusted to keep the system at steady-state operation or in other words the stoichiometric amount needed to react with the UF 6  feed from stream  11 . 
     The following examples demonstrate the practice and utility of the present invention, but are not to be construed as limiting the scope thereof. 
     EXAMPLES 
     Example 1 
     Example 1 is an example of the first reactor starting with a 38.92% HF solution. 3038.8 grams of an 38.92% HF/water solution were originally charged to a 3.7 liter vessel used as the pump/settling tank. A small diaphragm pump circulated the solution around a closed loop system and past a nozzle located inside a mixing tee which acted as the reactor. A UF 6  feed cylinder was prepared and placed on a scale. An inert gas, nitrogen (N 2 ), purge was flowing through the UF 6  feed line, out the nozzle and into the circulating HF solution to keep the nozzle free of moisture. The UF 6  feed was turned on and co-fed with the nitrogen. The nitrogen purge was decreased over time until it was completely turned off. A solution 38.92% HF, was added during the experiment totaling 621.2 grams. A total of 853.6 grams of UF 6  was fed to the reactor system. UO 2 F 2 /HF/water slurry material were drained out of the pump/settling tank periodically during the experiment. The reactor was kept at atmospheric pressure during the run by venting the vessel through a brine condenser. Any vapors that passed from the brine condenser were captured in an absorber filled with potassium hydroxide (KOH) solution of strength 27.30% KOH. After the run the resulting material in the reactor system, the caustic absorber, and the UO 2 F 2 /HF/water slurry collected during the run were analyzed and a detailed mass balance on HF, water, and UO 2 F 2  was performed. Results indicated that 99.06% of the theoretical amount of HF was collected, 98.58% of the UO 2 F 2  was accounted for and 91.71% of the water was accounted for. The UO 2 F 2  was analyzed for purity by testing it for % soluble fluorides. Since UO 2 F 2  is soluble in water the analysis for soluble fluorides is a good test to check its purity. An unexpected discovery was made using this analysis. The amount of soluble fluoride in the sample was found to be 11.50% and the amount of soluble fluoride in pure UO 2 F 2  is 12.34%. The amount of soluble fluoride in a UO 2 F 2  hydrate however is 11.62%. It was discovered that a hydrated UO 2 F 2 .H 2 O material is made when UF 6  reacts with water in the liquid form. See Table 1 for results. 
     Example 2 
     Example 2 is a demonstration of the second reactor starting with some of the slurry material collected from Example 1. Four experiments numbered 26-29 were conducted using a 2″ diameter MONEL muffle reactor with an external electric heating source. For each experiment a monel container was filled with about 9-10 grams of the UO 2 F 2 .H 2 O/HF/water slurry material. The composition of the slurry was 28.83% UO 2 F 2 .H 2 O, 32.83% HF, and 38.34% water. The boats were placed in the muffle reactor and heated to 649° C. for 15-30 minutes. The reactor was kept at atmospheric pressure by venting the reactor to a caustic absorber. A slight 20 cc/min nitrogen purge was put on the reactor. The % conversion is found by analyzing the material for soluble fluorides since UO 2 F 2  dissolves in water and the triuranyl octoxide product does not. The results found in Table 2 show that the conversion of UO 2 F 2  to U 3 O 8  was from about 58.8 to about 64% indicating that the HF and water had boiled off before the reaction was complete as the material left behind was dry. An additional source of water in the form of steam or HF/water azeotrope was fed to the second reactor to complete the reaction. See Table 2 for results. 
     Example 3 
     Example 3 is a demonstration of the second reactor using pre-dried UO 2 F 2 .H 2 O obtained from the experiment in example 1 and reacted to completion with a steam feed. Pre-dried UO 2 F 2 .H 2 O was obtained from the slurry material from Example 1 by putting a sample of the slurry in a platinum dish and drying it under a UV lamp. 43.6727 grams of slurry were placed in a platinum dish and dried over night. 12.5293 grams or 28.69% of the original material was left in the dish. It was analyzed for soluble fluorine and had 11.50% which is the amount found in a UO 2 F 2  hydrate, namely UO 2 F 2 .H 2 O. Eight experiments numbered 16-S-23S were run using the same reactor setup as above. Temperatures of 538 and 649° C. were used at different residence times and excess water amounts. All the experiments ran at 649° C. showed greater than 99.9% conversion of UO 2 F 2  to U 3 O 8  with only about 20.6 ppm to 87.6 ppm soluble fluoride left in the product. The experiments using 538° C. temperatures ranged from about 57 to about 90% conversion. See Table 3 for results. 
     Example 4 
     Example 4 is a demonstration of the second reactor using HF/water azeotrope as a water source instead of steam with pre-dried UO 2 F 2 .H 2 O obtained from the experiment in Example 1. One experiment numbered  33 -A was run using the same reactor setup as Example 3. A temperature of 649° C. was chosen. The experiment showed greater than 99.9% conversion of UO 2 F 2  to U 3 O 8  with about 2.23% soluble fluoride left in the product. See Table 4 for results. 
     Example 5 
     Example 5 is a demonstration of the second reactor using hydrogen to reduce the UO 2 F 2  to U 3 O 8  with pre-dried UO 2 F 2 .H 2 O obtained from the experiment in example 1 and reacted to completion. One experiment numbered  25 -H was run using the same reactor setup as above. A temperature of 649° C. was chosen and a 100 cc/min hydrogen feed with a 100 cc/min nitrogen (inert gas) co-feed was used. The experiment showed greater than 99.9% conversion of UO 2 F 2  to U 3 O 8  with less than 100 ppm soluble fluoride left in the product. See Table 5 for results. 
     Example 6 
     Example 6 is an example of the first reactor starting with a 64.73% HF solution. It demonstrates the first reactor with a high concentration of HF and the composition of the vapor that can be expected when the UF 6  feed is on. It is also an excellent demonstration of a flash distillation of the pump/settling tank contents. 3202.9 grams of an 64.73% HF/water solution were originally charged to a vessel used as the pump/settling tank. The solution was heated to its boiling point of about 78° C. A brine condenser was attached to the vapor port on the top of the vessel. The noncondensibles were vented from the vessel through the brine condenser until the vessel vapors comprised of HF/water were condensing and refluxing back into the tank. A small diaphragm pump circulated the solution around a closed loop system and past a nozzle located inside a mixing tee which acted as the reactor. A UF 6  feed cylinder was prepared and placed on a scale. An inert gas, N 2 , was flowing through the UF 6  feed line, out the nozzle and into the circulating HF solution to keep the nozzle free of moisture. The UF 6  feed was turned on and co-fed with the nitrogen. The nitrogen purge was decreased over time until it was completely turned off. Initially enough UF 6  was fed to saturate the HF solution with UO 2 F 2 . The UF 6  feed was stopped and a flash distillation was done on the saturated solution. A total of four reflux samples were taken and analyzed for %HF and concentration of uranium. They showed greater than 98% HF and between about 0.33 and 2.15 ppm uranium after reaching steady state. 
     The UF 6  feed was resumed using a slight, 0-130 cc/min, co-feed of nitrogen. During the time that UF 6  was being fed a total of four vapor reflux samples and analyzed for %HF and concentration of uranium. The feed rate of UF 6  was varied for each sample. The %HF ranged from about 93% to about 99%. The uranium concentration ranged from about 0.58 ppm to about 240 ppm. 
     A total of 392.9 grams of UF 6  was fed to the reactor system. The reactor was kept at atmospheric pressure during the run by venting the vessel through a brine condenser. Any vapors that escaped from the brine condenser were captured in a startup absorber filled with potassium hydroxide (KOH) solution of strength 20.53% KOH or a parallel run absorber filled with Distilled and Deionized water. After the run the resulting material in the reactor system, each absorber, and all samples collected during the run were analyzed and a detailed mass balance on HF, water, and UO 2 F 2  was done. Results indicated that 98.24% of the theoretical amount of HF was collected, 95.16% of the UO 2 F 2  was accounted for and 96.64% of the water was accounted for. Results of these experiments are summarized in Table 6. 
     Example 7 
     Example 7 demonstrated that a distillation column could make anhydrous hydrogen fluoride that was within existing commercial grade specifications for uranium. A distillation column was constructed consisting of a vessel with external electric heating source for a reboiler, a column packed with Kynar mesh packing, and a tube in tube condenser. The theoretical plates were calculated to be 10.6. 
     The results of vapor reflux samples taken from Example 7 were used to synthesize a representative reboiler charge. The charge consisted of 0.0958 grams of UO 2 F 2  added to 1481.6 grams of 64.73% HF solution to make up a reboiler charge with a 50 ppm uranium concentration. 
     The reboiler was heated to 79-80° C. until the reboiler contents boiled. The noncondensibles were vented off the top of the condenser through the brine condenser until a liquid reflux was established. The column pressure was kept at atmospheric pressure. After 1.25 hours a sample of the reflux liquid was taken and analyzed for HF concentration (by titration) and uranium content (by ICP-MS). The sample was high in uranium concentration as the column had not come to equilibrium yet. It was already seen that the distillation would work because of the results of the flash distillation experiment done earlier with a saturated (4.34% UO 2 F 2 ) 65% HF solution in example 6. Samples were taken periodically and analyzed for both HF concentration and U until the 1 ppm U spec was satisfied. Sample 4 had a 0.76 ppm U concentration. All samples taken were greater than 99% HF. Results of these experiments are summarized in Table 7. 
     
       
         
               
             
               
               
             
               
             
               
               
               
               
               
               
               
               
               
             
               
               
             
               
               
               
               
             
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 1st Reactor Mass Balance 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 IN 
               
               
                   
                   3670 total gms  38.92% HF solution 
               
               
                   
                 1428.4 grams of HF from starting and make-up solutions 
               
               
                   
                 2241.6 grams of H 2 O from starting and make-up solutions 
               
               
                   
                  853.5 total grams of UF 6  fed 
               
             
          
           
               
                 Theoretical amount of UO 2 F 2  and HF produced 
               
             
          
           
               
                   
                   
                 UF 6   
                 + 
                 2H 2 O 
                 −&gt; 
                 UO 2 F 2   
                 + 
                 4HF 
               
               
                   
                   
               
               
                   
                 Moles 
                  2.4 
                   
                  4.8 
                   
                  2.4 
                   
                  9.7 
               
               
                   
                 Grams 
                 853.5 
                   
                 97.0 
                   
                 746.8 
                   
                 194.0 
               
               
                   
                   
               
             
          
           
               
                   
                 1622.3 total grams of HF IN 
               
               
                   
                 2144.6 total grams of water IN 
               
               
                   
                 OUT 
               
               
                   
                 Total Out 
               
               
                   
                 1607.1 grams HF 
               
               
                   
                  736.2 grams UO 2 F 2   
               
               
                   
                 1966.8 grams H 2 O 
               
               
                   
                 Mass Balance Calculation 
               
             
          
           
               
                   
                 HF 
                 1607.1/1622.3*100 = 
                 99.06% 
               
               
                   
                 UO 2 F 2   
                 736.2/746.8*100 = 
                 98.58% 
               
               
                   
                 H 2 O 
                 1966.9/2144.6*100 = 
                 91.71% 
               
             
          
           
               
                   
                 Analysis of UO 2 F 2  product shows a soluble fluoride 
               
               
                   
                 content of 11.50% F − . This is a UO 2 F 2  hydrate because 
               
               
                   
                 pure UO 2 F 2  has 12.34% soluble F −  and UO 2 F 2 .H2O has 11.62% 
               
               
                   
                 soluble F − . 
               
               
                   
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                 2nd Reactor Pyrohydrolysis of UO 2 F 2 .H 2 O/HF/H 2 O Slurry 
               
               
                   
               
             
             
               
                 Purpose is to see if the slurry from the liquid phase reactor 
               
               
                 will react to completion without additional water feed. 
               
               
                 3UO 2 F 2  + 3H 2 O −&gt; U 3 O 8  + 6HF + 1/2O 2   
               
             
          
           
               
                   
                   
                 Residence 
                 Temp. ° C. 
                 * Soluble F −   
                 % Conv. 
               
               
                   
                 Act. slurry 
                 Time 
                 Actual 
                 in product 
                 of 
               
               
                 EXP # 
                 wt. (gm) 
                 (min) 
                 (Ave.) 
                 % 
                 UO 2 F 2   
               
               
                   
               
               
                 26 
                 8.9524 
                 30 
                 645 
                 4.42% 
                 64.2 
               
               
                 27 
                 9.5387 
                 30 
                 654 
                 5.08% 
                 58.8 
               
               
                 28 
                 9.2622 
                 30 
                 653 
                 4.40% 
                 64.3 
               
               
                 29 
                 9.2891 
                 30 
                 653 
                 4.68% 
                 62.1 
               
               
                   
               
               
                 The starting material was from the 1st reactor with a starting HF solution of 38.92% strength from Example 1. The uranium compound, by soluble F −  analysis, appears to be a UO 2 F 2 .H 2 O hydrate.  
               
               
                 * Note:  
               
               
                 Starting UO 2 F 2 .H 2 O hydrate had 11.50% soluble F −  by the same analytical method. Pure UO 2 F 2 .H 2 O has 11.65% soluble F − .  
               
             
          
         
       
     
     
       
         
               
             
               
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 3 
               
               
                   
               
               
                 Design of Experiments for 2nd Reactor Pyrohydrolysis 
               
               
                 Steam Feed 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                   
                   
                   
                   
                 Amount of 
                   
               
               
                 DESIGN 
                 Amount 
                   
                 Residence 
                 Feed rate 
                 Steam 
                 % Excess 
               
               
                 EXP # 
                 UO 2 F 2  (gms) 
                 Temp (° C.) 
                 Time (min) 
                 (g/min) 
                 feed (gms) 
                 H 2 O 
               
               
                   
               
               
                 16-S 
                 4.0 
                 649 
                 15 
                 0.33 
                 5 
                 2038.9 
               
               
                 17-S 
                 4.0 
                 649 
                 15 
                 1.00 
                 15 
                 6316.7 
               
               
                 18-S 
                 4.0 
                 649 
                 30 
                 0.17 
                 5 
                 2038.9 
               
               
                 19-S 
                 4.0 
                 649 
                 30 
                 0.50 
                 15 
                 6316.7 
               
               
                 20-S 
                 4.0 
                 538 
                 15 
                 0.33 
                 5 
                 2038.9 
               
               
                 21-S 
                 4.0 
                 538 
                 15 
                 1.00 
                 15 
                 6316.7 
               
               
                 22-S 
                 4.0 
                 538 
                 30 
                 0.17 
                 5 
                 2038.9 
               
               
                 23-S 
                 4.0 
                 538 
                 30 
                 0.50 
                 15 
                 6316.7 
               
               
                   
               
             
          
           
               
                 3UO 2 F 2  + 3H 2 O → U 3 O 8  + 6HF + ½O 2   
               
               
                   
               
             
          
           
               
                   
                   
                   
                 H 2 O needed 
                 U 3 O 8   
                 U 3 O 8   
                 U 3 O 8   
                 % Conv. 
                 H 2 O Feed 
                   
                 Temp. ° C. 
                 *Soluble F 
               
               
                 ACTUAL 
                 Act. UO 2 F 2   
                 UO 2 F 2   
                 wt. (gm) 
                 moles 
                 wt. (gm) 
                 wt. (gm) 
                 of 
                 wt. (gm) 
                 % excess 
                 Actual 
                 in product 
               
               
                 EXP # 
                 wt. (gm) 
                 moles 
                 Theory 
                 Theory 
                 Theory 
                 Actual 
                 UO 2 F 2   
                 Actual 
                 H 2 O 
                 (Ave.) 
                 ppm or % 
               
               
                   
               
               
                 16-S 
                 3.9998 
                 0.0130 
                 0.2338 
                 0.0043 
                 3.6448 
                 3.6774 
                 99.99 
                 5 
                 2039 
                 645 
                 &lt;75 
               
               
                 17-S 
                 4.0002 
                 0.0130 
                 0.2338 
                 0.0043 
                 3.6452 
                 3.6569 
                 99.99 
                 15 
                 6316 
                 654 
                 &lt;25 
               
               
                 18-S 
                 4.0002 
                 0.0130 
                 0.2338 
                 0.0043 
                 3.6452 
                 3.6812 
                 99.99 
                 5 
                 2039 
                 653 
                 &lt;90 
               
               
                 19-S 
                 4.0000 
                 0.0130 
                 0.2338 
                 0.0043 
                 3.6450 
                 3.6642 
                 99.99 
                 15 
                 6317 
                 653 
                 &lt;25 
               
               
                 20-S 
                 4.0002 
                 0.0130 
                 0.2338 
                 0.0043 
                 3.6452 
                 3.8676 
                 53.79 
                 5 
                 2039 
                 543 
                 5.31% 
               
               
                 21-S 
                 3.9999 
                 0.0130 
                 0.2338 
                 0.0043 
                 3.6449 
                 3.8177 
                 65.54 
                 15 
                 6317 
                 534 
                 3.96% 
               
               
                 22-S 
                 3.9999 
                 0.0130 
                 0.2338 
                 0.0043 
                 3.6449 
                 3.8539 
                 53.70 
                 5 
                 2039 
                 541 
                 5.32% 
               
               
                 23-S 
                 4.0002 
                 0.0130 
                 0.2338 
                 0.0043 
                 3.6452 
                 3.7163 
                 89.08 
                 15 
                 6316 
                 539 
                 1.26% 
               
               
                   
               
               
                 The starting material was from the 1st reactor with a starting HF solution of 38.92% strength from Example 1.  
               
               
                 The uranium compound, by soluble F −  analysis, appears to be a UO 2 F 2 .H 2 O hydrate.  
               
               
                 *Note:  
               
               
                 Starting UO 2 F 2 .H 2 O hydrate had 11.50% soluble F −  by the same analytical method. Pure UO 2 F 2 .H 2 O has 11.65% soluble F − .  
               
             
          
         
       
     
     
       
         
               
             
               
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 4 
               
               
                   
               
               
                 1st Reactor Material Pyrohydrolysis using HF/water Azeotrope as a Water Source 
               
               
                 HF/water azeo feed 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                   
                   
                   
                   
                 Amount of 
                   
               
               
                 DESIGN 
                 Amount 
                   
                 Residence 
                 Feed rate 
                 Steam 
                 % Excess 
               
               
                 EXP # 
                 UO 2 F 2   
                 Temp (° C.) 
                 Time (min) 
                 (g/min) 
                 feed (gms) 
                 H 2 O 
               
               
                   
               
               
                 33-A 
                 4.0 
                 649 
                 60 
                 0.50 
                 30 
                 12733.3 
               
               
                   
               
             
          
           
               
                 3UO 2 F 2  + 3H 2 O → U 3 O 8  + 6HF + ½O 2   
               
               
                   
               
             
          
           
               
                   
                   
                   
                 H 2 O needed 
                 U 3 O 8   
                 U 3 O 8   
                 U 3 O 8   
                 % Conv. 
                 H 2 O Feed 
                   
                 Temp. ° C. 
                 *Soluble F 
               
               
                 ACTUAL 
                 Act. UO 2 F 2   
                 UO 2 F 2   
                 wt. (gm) 
                 moles 
                 wt. (gm) 
                 wt. (gm) 
                 of 
                 wt. (gm) 
                 % excess 
                 Actual 
                 in product 
               
               
                 EXP # 
                 wt. (gm) 
                 moles 
                 Theory 
                 Theory 
                 Theory 
                 Actual 
                 UO 2 F 2   
                 Actual 
                 H 2 O 
                 (Ave.) 
                 ppm or % 
               
               
                   
               
               
                 33-A 
                 4.1530 
                 0.0135 
                 0.2427 
                 0.0045 
                 3.7844 
                 3.9601 
                 81.93 
                 35 
                 14321 
                 649 
                 2.23% 
               
               
                   
               
               
                 The starting material was from the 1st reactor with a starting HF solution of 38.92% strength from Example 1.  
               
               
                 The uranium compound, by soluble F −  analysis, appears to be a UO 2 F 2 .H 2 O hydrate.  
               
               
                 *Note:  
               
               
                 Starting UO 2 F 2 .H 2 O hydrate had 11.50% soluble F −  by the same analytical method. Pure UO 2 F 2 .H 2 O has 11.65% soluble F − .  
               
             
          
         
       
     
     
       
         
               
             
               
             
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 5 
               
               
                   
               
               
                 2nd Reactor Pyrohydrolysis Reactions of UO 2 F 2   
               
               
                 H 2  feed 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 2UO 2 F 2 .H 2 O + 2H 2  → 2UO 2 + 4HF + 2H 2 O 
               
               
                 3UO 2  + O 2  → U 3 O 8   
               
               
                   
               
             
          
           
               
                   
                   
                   
                   
                   
                 Nitrogen 
                 Hydrogen 
               
               
                   
                 DESIGN 
                 Amount 
                   
                 Residence 
                 Feed rate 
                 Feed rate 
               
               
                   
                 EXP # 
                 UO 2 F 2   
                 Temp (° C.) 
                 Time (min) 
                 (cc min) 
                 (cc/min) 
               
               
                   
                   
               
               
                   
                 25-H 
                 4.0 
                 649 
                 30 
                 100 
                 100 
               
               
                   
                   
               
             
          
           
               
                   
                 Actual 
                   
                 H 2  needed 
                 U 3 O 8   
                 U 3 O 8   
                   1  U 3 O 8   
                 % Conv. 
                 H 2  feed 
                   
                 Temp. ° C. 
                 *Soluble F 
               
               
                 ACTUAL 
                 UO 2 F 2 .H 2 O 
                 UO 2 F 2   
                 wt. (gm) 
                 moles 
                 wt. (gm) 
                 wt. (gm) 
                 of 
                 amount (g) 
                 % excess 
                 Actual 
                 in product 
               
               
                 EXP # 
                 wt. (gm) 
                 moles 
                 Theory 
                 Theory 
                 Theory 
                 Actual 
                 UO 2 F 2   
                 Actual 
                 H 2  feed 
                 (Ave.) 
                 ppm 
               
               
                   
               
               
                 25-H 
                 4.0009 
                 0.0126 
                 0.0252 
                 0.0042 
                 3.5312 
                 3.5581 
                 99.99 
                 4.65 
                 18384 
                 649 
                 &lt;100 
               
               
                   
               
               
                 The starting material was from the 1st reactor with a starting HF solution of 38.92% strength from Example 1.  
               
               
                 The uranium compound, by soluble F −  analysis, appears to be a UO 2 F 2 .H 2 O hydrate.  
               
               
                 *Note:  
               
               
                 Starting UO 2 F 2 .H 2 O hydrate had 11.50% soluble F −  by the same analytical method. Pure UO 2 F 2 .H 2 O has 11.65% soluble F − .  
               
               
                   1 The color of the product was a uniform deep olive green.  
               
             
          
         
       
     
     
       
         
               
             
               
               
             
               
             
               
               
               
               
               
               
               
               
               
             
               
               
             
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 6 
               
               
                   
               
               
                 1st Reactor Mass Balance 
               
               
                   
               
             
             
               
                 1st reactor was run with a starting HF solution concentration of 
               
               
                 64.73% HF. 
               
             
          
           
               
                   
                 IN 
               
               
                   
                 3202.9 grams of  64.73% HF solution 
               
               
                   
                 1129.7 grams of H 2 O from starting solution 
               
               
                   
                 2073.2 grams of HF from starting solution 
               
               
                   
                  392.9 total grams of UF 6  fed 
               
             
          
           
               
                 Theoretical amount of UO 2 F 2  and HF produced 
               
             
          
           
               
                   
                   
                 UF 6   
                 + 
                 2H 2 O 
                 −&gt; 
                 UO 2 F 2   
                 + 
                 4HF 
               
               
                   
                   
               
               
                   
                 Moles 
                   1.12 
                   
                  2.23 
                   
                   1.12 
                   
                  4.46 
               
               
                   
                 Grams 
                 392.9 
                   
                 44.6 
                   
                 343.8 
                   
                 89.3 
               
               
                   
                   
               
             
          
           
               
                   
                 2162.5 total grams of HF IN 
               
               
                   
                 1085.0 total grams of H 2 O IN 
               
               
                   
                 OUT 
               
               
                   
                 Total Out 
               
               
                   
                 2124.38 grams HF 
               
               
                   
                  327.15 grams UO 2 F 2   
               
               
                   
                 1048.51 grams H 2 O 
               
               
                   
                 Mass Balance Calculation 
               
             
          
           
               
                   
                 HF 
                 2124.38/2162.5*100 = 
                 98.24% 
               
               
                   
                 UO 2 F 2   
                 327.15/343.8*100 = 
                 95.16% 
               
               
                   
                 H 2 O 
                 1048.51/1085.0*100 = 
                 96.64% 
               
             
          
           
               
                 The results of the flash distillation of a 65% HF solution saturated 
               
               
                 with UO 2 F 2  are as follows: 
               
             
          
           
               
                   
                   
                 Elapsed 
                 Sample 
                   
                   
               
               
                   
                 Sample 
                 Time (min) 
                 Size (gm) 
                 % HF 
                 U conc. 
               
               
                   
                   
               
               
                   
                 1 
                  60 
                 11.76 
                 66.22 
                 &lt;1.40 ppm 
               
               
                   
                 2 
                  75 
                 18.86 
                 99.50 
                 &lt;0.36 ppm 
               
               
                   
                 3 
                 120 
                 24.52 
                 99.74 
                 &lt;0.35 ppm 
               
               
                   
                 4 
                 135 
                 12.96 
                 98.79 
                 &lt;2.16 ppm 
               
               
                   
                   
               
             
          
           
               
                 The results of the analysis of pump tank vapor samples when UF6 
               
               
                 feed was on are as follows: 
               
             
          
           
               
                   
                   
                 Sample 
                 UF 6  Rate 
                   
                   
               
               
                   
                 Sample 
                 Size (gm) 
                 (g/min) 
                 % HF 
                 U conc. 
               
               
                   
                   
               
               
                   
                 1 
                 10.39 
                 NA 
                 99.29 
                 &lt;0.58 ppm 
               
               
                   
                 2 
                 12.77 
                 3.5 
                 98.71 
                 &lt;0.14 ppm 
               
               
                   
                 3 
                  3.90 
                 1.4 
                 93.07 
                  &lt;240 ppm 
               
               
                   
                 4 
                 13.32 
                 4.8 
                 99.15 
                   &lt;11 ppm 
               
               
                   
                   
               
             
          
         
       
     
     
       
         
               
             
               
             
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 7 
               
               
                   
               
               
                 Distillation Results/Data 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 A distillation column was constructed consisting of a reboiler, 16″ L × 1″ OD column packed with 
               
               
                 Kynar mesh packing, and a tube in tube condenser. The theoretical plates were calculated to be 10.6. 
               
               
                 0.0958 grams of UO 2 F 2  were added to 1481.6 grams of 64.73% HF solution to make a 50 ppm uranium 
               
               
                 concentration reboiler charge. 
               
               
                 Samples were taken periodically and analysed for both HF and uranium concentration until the 1 ppm 
               
               
                 uranium spec (set as an experimental goal) was satisfied. Results/data are as follows: 
               
             
          
           
               
                   
                 Elapsed 
                 Sample 
                   
                   
               
               
                 Sample 
                 Time (min) 
                 Size (gm) 
                 % HF 
                 U conc. 
               
               
                   
               
               
                 1 
                  75 min 
                 35.05 
                 99.10 
                  &lt;54 ppm 
               
               
                 2 
                 174 min 
                 32.43 
                 99.25 
                   &lt;8 ppm 
               
               
                 3 
                 206 min 
                 32.24 
                 99.70 
                 &lt;1.6 ppm 
               
               
                 4 
                 248 min 
                 32.1  
                 99.00 
                 &lt;0.8 ppm 
               
               
                   
               
             
          
           
               
                   
                   
                   
                   
                   
                   
                 Splitter 
                   
               
               
                   
                   
                 Top 
                   
                 System 
                 Cooling 
                 Set Time 
               
               
                 Elapsed 
                 Reboiler 
                 Column 
                 Reflux 
                 Pressure 
                 in Temp 
                 seconds 
               
               
                 Time (min) 
                 Temp ° C. 
                 Temp ° C. 
                 Temp ° C. 
                 psig 
                 ° C. 
                 closed/open 
                 Comments 
               
               
                   
               
               
                 0 
                 79.1 
                 44 
                 35 
                 0 
                 −16.5 
                   
                 reflux visible 
               
               
                 9 
                 81.3 
                 44 
                 40 
                 0 
                 −16.4 
               
               
                 44 
                 84.1 
                 23 
                 23 
                 0 
                 −11.5 
               
               
                 77 
                 82.9 
                 21 
                 22 
                 0 
                 −18.8 
                 6/2 
                 start sample 1 
               
               
                 166 
                 86 
                 19 
                 20 
                 0 
                 −16.4 
                 6/1 
                 start sample 2 
               
               
                 176 
                 84.6 
                 17 
                 18 
                 0 
                 −16.7 
                 6/1 
                 end sample 1 
               
               
                 196 
                 90 
                 21 
                 22 
                 0 
                 −17.7 
                 8/1 
                 start sample 3 
               
               
                 215 
                 90.5 
                 21 
                 22 
                 0 
                 −17.1 
                 8/1 
                 end sample 3 
               
               
                 240 
                 94.5 
                 23 
                 24 
                 0 
                 −16.7 
                 15/1  
                 start sample 4 
               
               
                   
               
             
          
         
       
     
     From the Examples, it is apparent that the method of the invention provides a complete process that can run at low temperatures and pressures so that less expensive materials can be used to produce the apparatus. 
     While the particular process for recovery of anhydrous hydrogen fluoride and uranium oxide products from depleted, natural or enriched uranium hexafluoride as herein shown and disclosed in detail is fully capable of obtaining the objects and providing the advantages herein before stated, it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of operation herein shown other than as described in the appended claims.