JP5558232B2 - Rare metal recovery method and recovery equipment from high radioactive level waste liquid - Google Patents

Description

  Embodiments described herein relate generally to a method and an apparatus for recovering a rare metal from a high radioactive level waste liquid.

  A high radioactive level waste liquid generated during reprocessing of spent fuel contains a large amount of rare metals such as palladium (Pd), ruthenium (Ru), and rhodium (Rh). In the current reprocessing, these rare metals contained in the high-level waste liquid are not recovered, and the glass is solidified and disposed of in the vitrification process.

  However, there is a possibility that the rare metal contained in the high-level waste liquid is precipitated in the glass melting furnace for producing the vitrified body, causing a short circuit of the melting furnace and volatilizing some rare metal compounds. In addition, when the concentration of rare elements in the high-level waste liquid increases, there is a problem that the viscosity decreases and it is difficult to produce a vitrified body.

  Therefore, an attempt is made to electrolyze a high radioactive level waste liquid before the vitrification step, deposit rare metals on the cathode electrode, dissolve by electrolytic oxidation, and further recover by electrolytic reduction.

JP2003-161798

  An object of the present invention is to provide a new and simple method and apparatus for recovering rare metals from waste liquids with high radioactive levels.

  In order to solve the above-described problem, one aspect of the present invention is a method for recovering a rare metal from a high radioactive level waste liquid, and in a first tank in which an anode electrode and a cathode electrode are arranged to face each other, By introducing a high radioactive level waste liquid containing rare metal ions and / or rare metal oxide ions and applying a voltage between the anode electrode and the cathode electrode, the rare metal ions and / or on the cathode electrode A first step of depositing the rare metal oxide ion as a rare metal and / or rare metal oxide, and the rare metal and / or the rare metal oxide deposited on the cathode electrode using a scraper. And a second step of recovering. The present invention relates to a method of recovering a rare metal from a high radioactive level waste liquid.

Another embodiment of the present invention is an apparatus for recovering a rare metal from a high radioactive level waste liquid, which is a first apparatus for introducing and storing a high radioactive level waste liquid containing a rare metal ion and / or a rare metal oxide ion. A cathode electrode for depositing the rare metal ion and / or the rare metal oxide ion as a rare metal and / or rare metal oxide by applying a voltage in the first tank, and the cathode electrode, An anode electrode disposed oppositely, a scraper for recovering the rare metal and / or the rare metal oxide deposited on the cathode electrode, and supplying at least acid to the first tank to supply at least the cathode The surface of the electrode is washed with the acid, the residue of the rare metal and / or the rare metal oxide on the surface of the cathode electrode is dissolved, and the residue An acid supply means for obtaining an acid solution containing, a second tank for introducing and storing the acid solution, and depositing the residue in the acid solution by applying a voltage in the second tank The present invention relates to a device for recovering a rare metal from a high radioactive level waste liquid, characterized by comprising: an additional cathode electrode to be formed; and an additional anode electrode disposed opposite to the additional cathode electrode .

It is a figure which shows schematic structure of the collection | recovery apparatus of the rare metal in 1st Embodiment. It is a schematic block diagram which shows the part of the 1st tank and the anode electrode arrange | positioned in this tank, and the cathode electrode of the collection apparatus of the rare metal in 2nd Embodiment. It is a schematic block diagram which shows the part of the 1st tank and the anode electrode arrange | positioned in this tank, and the cathode electrode of the collection apparatus of the rare metal in 2nd Embodiment. It is a figure which shows schematic structure of the collection | recovery apparatus of the rare metal in 3rd Embodiment. It is a figure which shows schematic structure of the collection | recovery apparatus of the rare metal in 4th Embodiment. It is a figure which shows schematic structure of the collection | recovery apparatus of the rare metal in 5th Embodiment. It is a figure which shows schematic structure of the collection | recovery apparatus of the rare metal in 6th Embodiment. It is a figure which shows schematic structure of the collection | recovery apparatus of the rare metal in 7th Embodiment. It is a figure which shows schematic structure of the collection | recovery apparatus of the rare metal in 8th Embodiment.

  Hereinafter, a method for recovering a rare metal from a high radioactive level waste liquid according to the present invention and a recovery method will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a diagram showing a schematic configuration of a rare metal recovery apparatus in the present embodiment. As shown in FIG. 1, the processing apparatus 10 of the present embodiment includes a first tank 11, and an anode electrode 12 and a cathode electrode 13 that are opposed to each other in the first tank 11. A power source 15 for applying a predetermined voltage between these electrodes and a voltmeter 16 for measuring the potential of each electrode are connected to the anode electrode 12 and the cathode electrode 13. The potential of each electrode is measured with reference to the potential of the reference electrode 14 arranged in parallel with the anode electrode 12 and the cathode electrode 13. Further, a pipe 17 is connected to the first tank 11 so that a high radioactive level waste liquid is continuously supplied via a pump 18.

  In addition, since the 1st tank 11 introduces and stores a high radioactive level waste liquid, it is comprised from a stainless steel tank, a lid | cover, a liquid level meter, a dosimeter, an agitator (not shown) etc., for example. .

Next, a rare metal recovery method using the processing apparatus 10 shown in FIG. 1 will be described.
First, by using the pump 18 through the pipe 17, a highly radioactive waste liquid containing a rare metal is introduced into the first tank 11. In such waste liquid, rare metals exist in the form of ions or oxide ions. For example, since the present embodiment is intended for a high radioactive level waste liquid, that is, a high radioactive level waste liquid generated during spent fuel reprocessing as described above, palladium (Pd), ruthenium (Ru) are used as rare metals. , Rhodium (Rh), silver (Ag), molybdenum (Mo), technetium (Tc), and the like.

  Among these rare metals, Pd, Ru, Rh, and Ag mainly exist as metal ions (cations), and Tc and Mo mainly exist as oxide ions (anions). These metals may constitute other complex ions or the like, and may exist as anions. In this embodiment, oxide ions present as anions are also deposited on the cathode.

Next, after introducing the high radioactive level waste liquid into the first tank 11, a predetermined voltage is applied between the anode electrode 12 and the cathode electrode 13 by the power source 15, and rare metal ions or rare metal oxidation contained in the waste liquid is applied. Product ions are deposited on the cathode electrode 13 as a rare metal or a rare metal oxide, respectively. For example, Pd ions are deposited on the cathode electrode 13 based on a reaction formula such as Pd ²⁺ + 2e ⁻ → Pd.

  Next, the rare metal or the rare metal oxide deposited on the cathode electrode 13 is recovered using a scraper (not shown).

  Thus, according to the present embodiment, the rare metal or rare metal oxide of the high radioactive level waste liquid can be collected by a simple method of deposition on the cathode electrode 13 and collection by the scraper.

  In addition, since the high radioactive level waste liquid is continuously supplied by the pump 18, unlike the batch type, it is possible to continuously recover the rare metal or rare metal oxide from the high radioactive level waste liquid.

  In addition, in the processing apparatus 10 shown in FIG. 1, although the anode electrode 12 and the cathode electrode 13 are made into flat form, it can also be made into a cylindrical shape suitably in order to increase an electrode surface area. It is also possible to combine a plurality of cylindrical electrodes having different diameters.

(Second Embodiment)
2 and 3 are schematic configuration diagrams showing the first tank and the anode electrode and cathode electrode portions arranged in the tank of the rare metal recovery apparatus according to the present embodiment. Note that the same reference numerals are used for the same or similar components as the recovery apparatus 10 shown in FIG.

  In the first embodiment related to FIG. 1, the pair of anode electrode 12 and cathode electrode 13 are arranged in the first tank 11, but in the rare metal recovery apparatus of the present embodiment, the inside of the first tank 11 is arranged. A total of two pairs of anode and cathode electrodes are provided. Specifically, the anode electrode 12-1 and the cathode electrode 13-1 are paired and the anode electrode 12-2 and the cathode electrode 13-2 are paired so as to be disposed in the first tank 11. Yes.

  Therefore, in this embodiment, compared with the first embodiment, since a rare metal or a rare metal oxide can be deposited on the cathode electrodes 13-1 and 13-2, a large amount of rare metal or rare metal oxidation can be performed. Goods can be efficiently recovered. Note that, finally, the collected rare metal and the like are recovered using a scraper, as in the first embodiment.

  In the embodiment shown in FIG. 2, the anode electrodes 12-1, 12-2 and the cathode electrodes 13-1, 13-2 are arranged perpendicular to the introduction direction of the high radioactive level waste liquid, whereas in FIG. In the form shown, the anode electrodes 12-1 and 12-2 and the cathode electrodes 13-1 and 13-2 are arranged in parallel to the introduction direction of the high radioactive level waste liquid. Therefore, when the form shown in FIG. 2 is compared with the form shown in FIG. 3, it can be seen that the latter form has a larger area in contact with the waste liquid, so that a larger amount of rare metals can be efficiently recovered.

  In this embodiment, two pairs of anode electrodes and cathode electrodes are used, but three or more pairs of anode electrodes and cathode electrodes may be used as necessary.

  Since other features and advantages are the same as those of the first embodiment, description thereof will be omitted.

(Third embodiment)
FIG. 4 is a diagram showing a schematic configuration of the rare metal recovery apparatus in the present embodiment. Note that the same reference numerals are used for the same or similar components as the recovery apparatus 10 shown in FIG.

  In the rare metal recovery apparatus 20 of the present embodiment, an ion permeable insulating film 21 is disposed between the anode electrode 12 and the cathode electrode 13, so that the rare metal of the first embodiment relating to FIG. It differs from the metal recovery device 10.

  The high radioactive level waste liquid introduced into the first tank 11 reduces the resistance between the electrodes by reducing the distance between the anode electrode 12 and the cathode electrode 13 and can be electrolyzed with high efficiency. Ions and the like can be deposited with higher efficiency. However, if the distance between the anode electrode 12 and the cathode electrode 13 is made too small, a new problem of electrical short-circuiting due to contact between these electrodes arises.

  On the other hand, in this embodiment, since the ion-permeable insulating film 21 is provided between the anode electrode 12 and the cathode electrode 13, even when these electrodes are brought close to each other, these electrodes are in electrical contact with each other, There is no short circuit. Therefore, the distance between the anode electrode 12 and the cathode electrode 13 can be reduced while suppressing the electrical contact between the anode electrode 12 and the cathode electrode 13, so that the rare metal ions in the high radioactive level waste liquid introduced into the first tank 11 can be obtained. And the like can be precipitated with sufficiently high efficiency, and a large amount of rare metals and the like can be efficiently recovered by a subsequent scraper.

  As the ion-permeable insulating film 21, for example, an ion exchange membrane or a ceramic porous body can be used.

  Since other features and advantages are the same as those of the first embodiment, description thereof will be omitted.

(Fourth embodiment)
FIG. 5 is a diagram showing a schematic configuration of a rare metal recovery apparatus in the present embodiment. Note that the same reference numerals are used for the same or similar components as the recovery apparatus 10 shown in FIG.

  In the rare metal recovery apparatus 30 of this embodiment, the anode electrode 32 and the cathode electrode 33 are formed of a conductive porous body, and therefore the rare metal recovery apparatus 10 of the first embodiment with respect to FIG. 1 is used. Is different.

  By constituting the anode electrode 32 and the cathode electrode 33 from the conductive porous body as described above, the effective surface area of these electrodes is increased. Accordingly, the substantial contact area of these electrodes with the high radioactive level waste liquid is increased, so that a large amount of rare metal ions and the like in the waste liquid can be deposited as rare metals. As a result, a large amount of rare metals and the like can be efficiently recovered through subsequent recovery by a scraper.

  In addition, as the conductive porous body, carbon fiber that hardly generates hydrogen gas or the like, or a metallic porous body such as tantalum can be used.

  Since other features and advantages are the same as those of the first embodiment, description thereof will be omitted.

(Fifth embodiment)
FIG. 6 is a diagram showing a schematic configuration of a rare metal recovery apparatus in the present embodiment. Note that the same reference numerals are used for the same or similar components as the recovery apparatus 10 shown in FIG.

  In the rare metal recovery apparatus 40 of the present embodiment, instead of disposing the anode electrode 12 in the first tank 11, at least both side surfaces of the first tank 11 are configured by the metal plates 43, and the first tank 11 is made to function as an anode. As a result, a large-area cathode electrode 13 can be arranged in the first tank 11 and a large number of cathode electrodes 13 can be arranged. Insulation between the metal plate 43 and the pipe 17 is performed by a method such as interposing an insulating material at these contact portions, for example.

  Therefore, since the substantial area of the cathode electrode 13 and the cathode electrode is increased, a large amount of rare metal ions or the like in the high radioactive level waste liquid can be deposited on the cathode electrode 13 and recovered by a later scraper. be able to. That is, according to the present embodiment, a large amount of rare metal ions or the like in the waste liquid can be precipitated as a rare metal or the like, and can be efficiently recovered.

  Since other features and advantages are the same as those of the first embodiment, description thereof will be omitted.

(Sixth embodiment)
FIG. 7 is a diagram showing a schematic configuration of a rare metal recovery apparatus in the present embodiment. Note that the same reference numerals are used for the same or similar components as the recovery apparatus 10 shown in FIG.

  In the rare metal recovery device 50 of the present embodiment, the member 51 is provided in the first tank 11 so as to face the length direction of the pipe 17, that is, the opening to the first tank 11. Thus, it is different from the collection device 10 in the first embodiment.

  In the recovery apparatus 50 of the present embodiment, the flow of the high radioactive level waste liquid introduced into the first tank 11 from the pipe 17 by the member 51 is divided, so that the waste liquid is contained in the first tank 11. To be stirred. Therefore, since the concentration distribution of the rare metal ions or rare metal oxide ions in the waste liquid in the first tank 11 is kept uniform, a voltage is applied between the anode electrode 12 and the cathode electrode 13, Rare metals or rare metal oxides can be precipitated, and the efficiency when recovered with a scraper can be improved.

  Note that the member 51 may be any of a rod-like member, a plate-like member, and the like as long as the above-described effects are achieved.

  Since other features and advantages are the same as those of the first embodiment, description thereof will be omitted.

(Seventh embodiment)
FIG. 8 is a diagram showing a schematic configuration of a rare metal recovery apparatus in the present embodiment. Note that the same reference numerals are used for the same or similar components as the recovery apparatus 10 shown in FIG.

  In the rare metal recovery device 60 of the present embodiment, a gas pipe 67 having one end opened to the atmosphere is provided in the upper part of the first tank 11 and is connected to the gas pipe 67 and the pipe 17. An additional pipe 68 is provided, which is different from the recovery device 10 in the first embodiment.

  As described in the first embodiment, when an electrolytic reaction occurs between the anode electrode 12 and the cathode electrode 13 and a rare metal or the like is deposited on the anode electrode 12, hydrogen gas is generated at the same time. Oxygen gas is generated at the cathode electrode 13. Therefore, if these gases are left as they are, the pressure in the first tank 11 increases, and it may be difficult to introduce the high radioactive level waste liquid into the first tank 11.

  However, in the present embodiment, as shown in FIG. 8, since the gas pipe 67 having one end opened to the atmosphere is provided in the upper part of the first tank 11, the gas generated in the first tank 11 is The gas is discharged to the outside through the gas pipe 67. Therefore, the disadvantages as described above can be eliminated.

  Further, if the amount of the high radioactive level waste liquid introduced into the first tank 11 by the pump 18 is temporarily introduced beyond the allowable range, for example, the electrolytic treatment is sufficiently performed in the first tank 11. It may be discharged without. Further, when the gas pipe 67 is provided as shown in FIG. 8, it may leak (overflow) to the outside through the gas pipe 67.

  However, in this embodiment, since the additional pipe 68 is provided as shown in FIG. 8, as described above, even when the high radioactive level waste liquid is temporarily introduced beyond the allowable range, It is returned to the pipe 17 by the additional pipe 68 and further returned to the first tank 11. That is, by providing the additional pipe 68, the high radioactive level waste liquid introduced into the first tank 11 beyond the allowable range is returned to the first tank 11. Therefore, precipitation and collection | recovery of the rare metal etc. in the said waste liquid can be performed, preventing the overflow from the system (1st tank 11) of a high radioactive level waste liquid.

  Since other features and advantages are the same as those of the first embodiment, description thereof will be omitted.

(Eighth embodiment)
FIG. 9 is a diagram showing a schematic configuration of a rare metal recovery apparatus in the present embodiment. Note that the same reference numerals are used for the same or similar components as the recovery apparatus 10 shown in FIG.

  In the rare metal recovery apparatus 70 of the present embodiment, a pipe 77 for supplying acid into the first tank 11 is connected to the pipe 17 on the upstream side of the first tank 11. The pipe 77 functions as a means for supplying acid into the first tank 11 together with a pump (not shown).

  Further, on the downstream side of the first tank 11, a second tank 71 for introducing and storing an acid solution described below is provided, and the second tank 71 is connected to the first tank by a pipe 79. Before and after the tank 11, it is connected to the pipe 17 on the downstream side of the pipe 77. The pipe 79 is provided with a pump 78 so that the acid obtained in the second tank 71 can be supplied again into the first tank 11. The pump 78 and the pipe 79 constitute an acid recovery supply means.

  Further, an additional anode electrode 72 and an additional cathode electrode 73 are provided in the second tank 71 so as to face each other, and as described below, acid is regenerated from the acid solution by electrolytic treatment. It is for making it happen.

  In addition, since the 1st tank 71 introduces and stores the acid solution of a high radioactive level, it is from a stainless steel tank, a lid | cover, a liquid level meter, a dosimeter, an agitator (not shown) etc., for example. Configure.

Next, a rare metal recovery method using the recovery device 70 shown in FIG. 9 will be described.
As in the first embodiment, by using the pump 18 through the pipe 17 first, waste liquid with a high radioactive level containing a rare metal is introduced into the first tank 11. Next, after introducing the high radioactive level waste liquid into the first tank 11, a predetermined voltage is applied between the anode electrode 12 and the cathode electrode 13 by the power source 15, and the rare metal ion or the rare metal oxide contained in the waste liquid is applied. Ions are deposited on the cathode electrode 13 as a rare metal or a rare metal oxide, respectively.

  Next, the rare metal or the rare metal oxide deposited on the cathode electrode 13 is recovered using a scraper (not shown). However, deposits may remain on the cathode electrode 13 only by using a scraper. As described above, if the deposits are left on the cathode electrode 13, not only the rare metal in the high radioactive level waste liquid can be recovered, but also radioactive materials are deposited on the cathode electrode 13. In many cases, it must be replaced after a predetermined time.

  However, in the present embodiment, after recovering the precipitate on the cathode electrode 13 as described above, an acid such as nitric acid or sulfuric acid is introduced into the first tank 11 through the pipe 77, and in particular, the cathode electrode. 13, that is, a rare metal or a rare metal oxide is dissolved with an acid to obtain an acid solution containing such a residue, which is introduced into the second tank 71.

  Next, in the second tank 71, a voltage is applied between the additional anode electrode 72 and the additional cathode electrode 73 from a power source (not shown), and the residue contained in the acid solution is deposited on the cathode electrode 73, for example. The residue thus deposited can be recovered again using a scraper. Therefore, the recovery efficiency of rare metals or rare metal oxides from the high radioactive level waste liquid is increased, and more rare metals can be recovered.

  In addition, after the residue is deposited and removed from the acid solution, the acid solution is composed only of the acid, so that the pump 78 is driven and introduced into the first tank 11 again through the pipe 79. can do. That is, after the acid is once introduced from the pipe 77, the residue is removed in the second tank 71 to return to the original acid, and the acid is returned to the first tank 11 many times, thereby the cathode. The precipitate can be repeatedly dissolved and removed on the electrode 13. As a result, the deposit on the cathode electrode 13, that is, a rare metal or a rare metal oxide can be efficiently recovered without using extra acid.

  Since other features and advantages are the same as those of the first embodiment, description thereof will be omitted.

  Although not particularly illustrated, the additional anode electrode 72 and the additional cathode electrode 73 in the second tank 71 can also have the same configurations as those of the second to fifth embodiments described above.

  Further, as in the sixth embodiment, a member for stirring the solution can be provided, and as in the seventh embodiment, a gas pipe for releasing the generated gas and an acid solution are circulated. It is also possible to provide such a pipe.

  The present invention has been described in detail based on the above specific examples. However, the present invention is not limited to the above specific examples, and various modifications and changes can be made without departing from the scope of the present invention.

10, 20, 30, 40, 50, 60, 70 Rare metal recovery device 11 First tank 12, 12-1, 12-2 Anode electrode 13, 13-1, 13-2 Cathode electrode 14 Reference electrode 15 Power supply DESCRIPTION OF SYMBOLS 16 Voltmeter 17 Piping 18 Pump 21 Ion permeable insulating film 32 Anode electrode which consists of electroconductive porous body 33 Cathode electrode which consists of electroconductive porous body 43 Metal plate 51 Member which divides the flow of high radioactive level waste liquid 67 Gas piping 68 Piping 71 Second tank 72 Additional anode electrode 73 Additional cathode electrode 77 Piping 78 Pump 79 Piping

Claims (5)

A method for recovering rare metals from waste liquids with high radioactive levels,
A high radioactive level waste liquid containing a rare metal ion and / or a rare metal oxide ion is introduced into a first tank in which the anode electrode and the cathode electrode are arranged to face each other, and the gap between the anode electrode and the cathode electrode is introduced. A first step of depositing the rare metal ions and / or the rare metal oxide ions as rare metals and / or rare metal oxides on the cathode electrode by applying a voltage to the cathode electrode;
A second step of recovering the rare metal and / or the rare metal oxide deposited on the cathode electrode using a scraper;
A method for recovering a rare metal from a high radioactive level waste liquid. After the second step, an acid is supplied into the first tank to clean at least the surface of the cathode electrode with the acid, and the rare metal and / or the rare metal oxidation on the surface of the cathode electrode is performed. A third step of dissolving the residue of the product to obtain an acid solution containing the residue;
By introducing the acid solution into a second tank in which an additional anode electrode and an additional cathode electrode are arranged to face each other, and applying a voltage between the additional anode electrode and the additional cathode electrode A fourth step of depositing the residue in the acid solution on the additional cathode electrode;
The method for recovering a rare metal from a high radioactive level waste liquid according to claim 1, comprising:   After the fourth step, the method includes a fifth step of collecting the acid obtained by removing the residue from the acid solution and re-feeding the acid into the first tank. A method for recovering a rare metal from a high radioactive level waste liquid according to claim 2. A device for recovering rare metals from waste liquids with high radioactive levels,
A first tank for introducing and storing a high radioactive level waste liquid containing rare metal ions and / or rare metal oxide ions;
In the first tank, a cathode electrode for depositing the rare metal ions and / or the rare metal oxide ions as rare metals and / or rare metal oxides by applying a voltage, and an anode disposed opposite to the cathode electrode Electrodes,
A scraper for recovering the rare metal and / or the rare metal oxide deposited on the cathode electrode;
Supplying acid into the first tank to wash at least the surface of the cathode electrode with the acid, and dissolving the rare metal and / or the rare metal oxide residue on the surface of the cathode electrode; An acid supply means for obtaining an acid solution containing the residue;
A second tank for introducing and storing the acid solution;
In the second tank, an additional cathode electrode for depositing the residue in the acid solution by applying a voltage, and an additional anode electrode disposed opposite to the additional cathode electrode;
A device for recovering rare metals from waste liquids with high radioactive levels. 5. The high supply according to claim 4 , further comprising a recovery supply means for recovering the acid obtained by removing the residue from the acid solution and resupplying the acid into the first tank. Rare metal recovery equipment from radioactive liquid waste.

Images