Method for recovering Ra-226, method for producing Ra-226 solution, and method for producing Ac-225 solution

Abstract

An embodiment of the present invention relates to a 226Ra recovery method, the 226Ra recovery method including a step (A1) in which a 226Ra-containing substance that is in a solid state and a carrier that has the function of adsorping 226Ra ions are immersed in a treatment solution, after which the treatment solution is irradiated with ultrasonic waves.

Description

[Technical Field]

[0001] One aspect of the present invention is 226 How to collect Ra, 226 How to make Ra solution 225 This relates to the method for producing Ac solution. [Background technology]

[0002] In the field of nuclear medicine, RI internal therapy is performed, in which drugs containing radioisotopes (RI) are selectively introduced into lesions such as tumors. Among radiation types, alpha rays have the characteristic of having a short range, which means that they have little effect on unnecessary exposure to surrounding normal cells. One of the alpha-emitting nuclides is 225 Ac is a radionuclide with a half-life of 10 days, and has recently been considered a promising therapeutic nuclide for cancer treatment.

[0003] 225 Ac is, for example, using an accelerator 226 It is produced by the (p,2n) nuclear reaction by irradiating a Ra target with protons. 225 To produce Ac, 226 As a raw material for Ra targets 226 Ra is required. 226 Until the early 1900s, Ra was produced in factories from ore and processed into radium sources for radiation therapy, but in recent years it has hardly been produced. Therefore, radium sources and other already produced 226 Substances containing Ra and 226 From other naturally collected materials containing Ra 226 Technology to recover Ra is needed.

[0004] Generally, from a radium source 226 When recovering Ra, from the radium source 226 A portion of the Ra-containing material was collected and the radium source was 226 After determining the chemical form of Ra, use a treatment method appropriate for that chemical form. 226 Methods for extracting and recovering Ra are known. for example,226 If the chemical form of Ra is radium sulfate, it is heated in an aqueous solution of sodium carbonate to produce radium carbonate, which is then filtered, washed, and dissolved in acid. 226 Retrieve Ra.

[0005] 226 If the chemical form of Ra is radium chloride, dissolve it in water, 226 Retrieve Ra. 226 If the chemical form of Ra is radium carbonate, filter the radium carbonate, wash the residue, and then dissolve it in acid. 226 Retrieve Ra. In addition, Non-Patent Document 1 describes the synthesis of radium sulfate from solid radium sulfate. 226 We are currently attempting to isolate Ra and evaluating its efficiency. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] Jan Kozempel et al., Dissolution of [226Ra]BaSO4 as part of a method for recovery of 226Ra from aged Radium sources., J.Radioanal.Nucl.Chem., 2015, 304, 337-342 Summary of the Invention [Problem to be solved by the invention]

[0007] The above-mentioned conventional method has the following problems. From radium sources 226 The procedure for collecting Ra samples was difficult and cumbersome, so there was a high possibility of exposure. · 226 It was also difficult to identify the chemical form of Ra, making it impossible to select an appropriate treatment method in some cases. The conversion efficiency of radium sulfate to radium carbonate is not 100%, and radium sulfate and radium carbonate are slightly soluble in water. 226 The recovery rate of Ra was low. · 226 If salts or used reagents remain in the Ra recovered material, 226 For Ra target manufacturing 226 There was a concern that the electrodeposition rate would decrease when electrodepositing Ra.

[0008] In Non-Patent Document 1, several methods are 226 We have succeeded in quantitatively isolating Ra, but the 226 The reagents for Ra adsorption, especially EDTA, must be dissolved in water. 226 A step is required to separate the Ra-EDTA from the aqueous matrix. 226 Ra and EDTA form a strong chelate bond, so 226 This requires a step to liberate Ra, which makes the process complicated and increases the risk of exposure to radiation.

[0009] One aspect of the present invention is 226 How to collect Ra, 226 Ra solution manufacturing method and 225 Provided is a method for producing Ac solution. [Means for solving the problem]

[0010] One aspect of the present invention is a solid 226 A Ra-containing material; 226 The method includes a step (A1) of immersing a carrier having a function of adsorbing Ra ions in a treatment liquid and then irradiating the treatment liquid with ultrasonic waves. 226 This is a method of recovering Ra.

[0011] Another aspect of the present invention is a solid 226 A Ra-containing material; 226A process (A1) of immersing a carrier having a function of adsorbing Ra ions in a treatment liquid, and then irradiating the treatment liquid with ultrasonic waves, a process (A2) of separating the carrier from the treatment liquid, and a process (A3) of removing the carrier from the carrier separated in the process (A2) using an acid. 226 comprising a step (A3) of eluting Ra; 226 This is a method for producing Ra solution.

[0012] Furthermore, another aspect of the present invention is the 226 The manufacturing method of Ra solution 226 A step (B1) of obtaining a Ra solution; 226 From Ra solution 225 and a step (B2) of preparing an Ac solution; 225 This is the method for producing Ac solution. [Effects of the Invention]

[0013] It is one aspect of the present invention 226 According to the Ra recovery method, 226 Even if the chemical form of Ra is unknown, it can be efficiently and simply 226 In addition, Ra can be recovered. 226 According to the method for producing the Ra solution, 226 Even if the chemical form of Ra is unknown, it can be efficiently and simply 226 The Ra solution can be produced. 225 According to the method for producing Ac solution, 226 Efficiently using Ra solution 225 An Ac solution can be prepared. DETAILED DESCRIPTION OF THE INVENTION

[0014] Next, the terms "to" of the present invention will be specifically explained. Unless otherwise specified, the expression "A to B" regarding a numerical range means that it is equal to or greater than A and equal to or less than B. Furthermore, % means % by mass.

[0015] [ 226 How to collect Ra] It is one aspect of the present invention226 The recovery method of Ra (hereinafter also referred to as "recovery method (X)") is a solid 226 A Ra-containing material; 226 The method includes a step (A1) of immersing a carrier having the function of adsorbing Ra ions (hereinafter also referred to as "carrier (i)") in a treatment liquid, and then irradiating the treatment liquid with ultrasonic waves.

[0016] <Process (A1)> In step (A1), a solid 226 The Ra-containing substance and the carrier (i) are immersed in a treatment liquid, and then the treatment liquid is irradiated with ultrasonic waves. In step (A1), the carrier (i) 226 The conditions are not particularly limited as long as Ra ions can be adsorbed, but for example, the adsorption can be carried out under neutral or alkaline conditions, and is preferably carried out under alkaline conditions. The alkaline conditions are more preferably alkaline conditions in which the pH is adjusted using at least one selected from the group consisting of ammonia, alkali metal hydroxides, alkali metal carbonates, and alkaline buffer solutions. 226 Metal ions (aluminum, zinc, iron, lead, copper, silver, etc.) contained in the Ra-containing substance that tend to precipitate under alkaline conditions can be precipitated, making them less likely to be adsorbed onto the carrier (i). 226 It is more preferable that the step (A1) is carried out under alkaline conditions in which the pH is adjusted using ammonia. This prevents alkali metal salts from remaining in the subsequent steps, and the recovered Ra can be efficiently adsorbed onto the carrier (i). 226 It can be used suitably in applications where residual alkali metal salts may have adverse effects, such as when a solution containing Ra is used for electrodeposition. 226 The applications of solutions containing Ra will be broadened.

[0017] Examples of alkali metal hydroxides include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, and cesium hydroxide. Examples of alkali metal carbonates include sodium carbonate, potassium carbonate, lithium carbonate, and cesium carbonate. Examples of alkaline buffer solutions include borate buffer solutions, Tris buffer solutions, phosphate buffer solutions, and McIlvaine buffer solutions.

[0018] When adjusting the pH to an alkaline condition, the pH adjustment may be performed at any timing before the treatment liquid is brought into contact with the carrier (i). 226 The Ra-containing material may be immersed in a treatment solution under neutral conditions and then placed under alkaline conditions, or in a solid state. 226 The Ra-containing material may be immersed in the treatment solution and simultaneously placed under alkaline conditions. 226 The Ra-containing material may be brought into an alkaline condition before being immersed in the treatment solution.

[0019] <Solid 226 Ra-containing substances> solid 226 Ra-containing materials are 226 There are no particular restrictions on the substance as long as it contains Ra and is solid at 25°C. 226 This means that the Ra-containing substance does not have fluidity when left standing on a horizontal surface at 25°C. solid 226 The Ra-containing substance is preferably at least one selected from the group consisting of uranium slag and a radium source.

[0020] Here, for radiation therapy 226 Radium sources in which Ra is sealed are well known. The structure of the radium source is not particularly limited, and sources with various structures can be used. Usually, 226 Ra is hermetically housed in a single or double casing made of, for example, iron, titanium, platinum, platinum iridium, or the like.

[0021] The shape and size of the radium source are not particularly limited, and examples of the shape include needle (long rod), tubular, plate, rugby ball, and spherical, with needle (long rod) being preferred. The size is preferably 1 to 50 mm in length and 0.5 to 5.0 mm in diameter. Included in radium sources 226 The chemical form of Ra is not particularly limited, and various chemical forms can be used. 226 The chemical form of Ra is often radium sulfate, and more rarely radium bromide.

[0022] Uranium slag (also called slag) is a waste material separated during the refining of uranium ore, and there are no particular restrictions on its composition or refining process. The crude refining of uranium ore is carried out, for example, through the following steps.

[0023] Uranium ore is crushed and pulverized, dissolved in acid or alkali, and the uranium is leached into a liquid, followed by solid-liquid separation. The resulting liquid is then subjected to solvent extraction using an ion exchange resin to remove impurities and concentrate the uranium, yielding a purified uranium liquid. The uranium purified liquid is allowed to stand and the precipitate is called yellowcake. Therefore, more specifically, uranium slag refers to the solid obtained by solid-liquid separation in the above-mentioned process and the waste liquid generated during the process of obtaining yellowcake from the uranium purified liquid. In other words, uranium slag includes both solid and liquid uranium slag.

[0024] Uranium ore, although its concentration is very small, 226 Includes Ra. In the rough refining process 226 Since Ra migrates to the slag, the solid slag (solid obtained by solid-liquid separation) and the liquid slag (waste liquid produced in the process of obtaining yellow cake from uranium refining liquid) 226 Contains Ra. Solid and liquid slag 226 The Ra content can vary depending on the type of uranium ore and the uranium refining process, but is thought to be higher in solid slag.

[0025] The process of obtaining yellowcake from uranium ore is generally called rough refining, and is carried out at a plant attached to the uranium mine. Uranium tailings are dumped in large quantities into a uranium tailings dam adjacent to the plant. Therefore, 226 Recovering Ra is a finite resource on Earth. 226 Not only can you use Ra efficiently, 226 It is also significant in that it can prevent environmental pollution caused by Ra.

[0026] <Carrier (i)> The carrier (i) is 226 There are no particular limitations on the carrier (i) as long as it has the function of adsorbing Ra ions. The carrier (i) is preferably a carrier that can form a complex with metal ions under acidic or alkaline conditions and elute the metal ions under alkaline or acidic conditions, which are opposite to the conditions under which the complex was formed. Examples of the carrier (i) include: 226 A carrier capable of exchanging Ra ions is exemplified, and preferably 226 It is a carrier having groups that can exchange Ra ions. 226 Specific examples of groups capable of exchanging Ra ions include carriers having an iminodiacetic acid group, a polyamine group, or a methylglycan group, with the iminodiacetic acid group being preferred. 226 Carriers with groups that can exchange Ra ions are solid phase carriers such as resins. 226 There are no particular limitations as long as a group capable of exchanging Ra ions is retained. 226 A preferred example of a carrier having a group capable of exchanging Ra ions is a styrene-divinylbenzene copolymer having an iminodiacetic acid group. Commercially available resins having such iminodiacetic acid groups include the "Chelex" series manufactured by Bio-Rad, the "Diaion" series manufactured by Mitsubishi Chemical, and the "Amberlite" series manufactured by Dow Chemical. More specifically, Bio-Rad's "Chelex 100" (particle size: 50-100 mesh, ion type: Na type, Fe type) can be mentioned.

[0027] Another example of the carrier (i) is a carrier containing a compound represented by the following formula (B): Commercially available carriers of this type include "Ln Resin," "Ln2 Resin," and "Ln3 Resin" manufactured by Eichrom Technologies.

[0028] [ka]

[0029] In formula (B), R 5 and R 6 are each independently -R' or -OR' (R' is an alkyl group having 8 carbon atoms). The alkyl group having 8 carbon atoms in R' may be linear or branched, and preferred examples include an octyl group, a 2-ethylhexyl group, and a 2-methyl-4,4-dimethylpentyl group.

[0030] Suitable examples of the compound represented by formula (B) include compounds represented by the following formulae (B-1) to (B-3).

[0031] [ka]

[0032] [ka]

[0033] [ka]

[0034] Another example of the carrier (i) is a carrier containing 1-octanol containing a compound represented by the following formula (III): Specifically, the carrier is a carrier containing 1-octanol containing 4,4'-bis(t-butylcyclohexano)-18-crown-6 or a carrier containing 1-octanol containing 4,5'-bis(t-butylcyclohexano)-18-crown-6. An example of a commercially available carrier (i) is "Sr Resin" manufactured by Eichrom Technologies.

[0035] [ka]

[0036] The amount of the carrier (i) used is not particularly limited. 226 The amount can be determined according to the amount of Ra-containing material. 226 When the Ra-containing substance is a radium source, for example, if the radium source is 10 mg or less, about 1 mL of carrier (i) can be used.

[0037] The carrier (i) is preferably used by being filled in a bag or a pack. The bag or pack can be filled with the carrier (i), 226 Although there are no particular limitations on the bag or pack as long as it does not adsorb Ra, it is preferably a mesh bag or pack made of an α-olefin such as polyethylene or polypropylene, and more preferably a mesh bag made of at least one selected from polyethylene and polypropylene. There are also no particular limitations on the shape and size of the bag or pack, but it is preferably a 2 cm square bag, and more preferably a 2 cm square tetrahedron. By using the bag or pack, the step (A2) of separating the carrier (i) from the treatment solution can be easily carried out. 226 After Ra has been eluted, the carrier (i) can be simply disposed of in the bag or pack without radioactive contamination of other instruments and equipment.

[0038] <Processing liquid> The processing liquid is a solid226 This liquid contains water as a solvent and is used to immerse the Ra-containing substance and the carrier (i). The content of water in the treatment solution is not particularly limited, but 226 The more the amount, the more solvent the Ra ions dissolve in, and the less ultrasonic waves are attenuated, so the more preferable. The treatment liquid may contain a liquid other than water, such as ethanol, methanol, glycerin, etc. Furthermore, a preservative or the like may be added to these solutions. The treatment liquid may contain liquid slag. When the treatment liquid contains liquid slag, the treatment liquid can extract not only from the solid slag but also from the liquid slag. 226 Ra is recovered, so it is recovered as a result 226 This is preferable because it increases the amount of Ra.

[0039] The pH of the treatment liquid is not particularly limited. For example, when step (A1) is carried out under alkaline conditions, the treatment liquid is preferably an alkaline aqueous solution, and the pH is preferably 8 or higher, more preferably 9 or higher. The pH is preferably adjusted using at least one selected from the group consisting of ammonia, hydroxides or carbonates of alkali metals, and alkaline buffer solutions. This allows 226 Ra can be adsorbed onto a support (i).

[0040] The treatment liquid preferably does not contain alkaline earth metals. Since alkaline earth metals are easily adsorbed onto the carrier (i), if the treatment liquid does not contain alkaline earth metals, 226 It is easy to avoid recovering alkaline earth metals together with Ra.

[0041] The amount of the treatment liquid is not particularly limited, but is preferably an amount that allows at least the entire carrier (i) to be completely immersed in the treatment liquid. When the carrier (i) is packed in a bag or a pack, the amount is preferably an amount that allows the entire bag or pack to be completely immersed in the treatment liquid.

[0042] <Ultrasonic irradiation> The frequency of the ultrasonic waves to be irradiated is not particularly limited as long as it is 16 kHz or more, but is preferably 16 to 120 kHz, more preferably 19 to 100 kHz, and even more preferably 20 to 80 kHz. When the frequency of the ultrasonic waves is within the above range, the solid 226 From Ra-containing materials 226 Efficiently extract Ra, 226 Ra can be efficiently adsorbed onto the carrier (i).

[0043] The ultrasonic generator is not particularly limited, and for example, a water tank type ultrasonic cleaner, an ultrasonic crusher (also called an ultrasonic disperser or an ultrasonic homogenizer), etc. A water tank type ultrasonic cleaner is preferred because it can irradiate ultrasonic waves without radioactively contaminating the ultrasonic generator.

[0044] The output of the ultrasonic generator is not particularly limited, but is preferably 10 to 800 W, more preferably 20 to 600 W, and even more preferably 30 to 400 W. When the output of the ultrasonic generator is within the above range, the solid 226 From Ra-containing materials 226 Efficiently extract Ra, 226 Ra can be efficiently adsorbed onto the carrier (i). The ultrasonic generator may be provided with a thermostatic bath to prevent the temperature of the ultrasonic generator and the treatment liquid from rising due to the irradiation of ultrasonic waves. The temperature of the thermostatic bath is, for example, 10 to 25°C.

[0045] Ultrasonic irradiation can be carried out once or multiple times at appropriate intervals, for example, once or 2 to 5 times per day, preferably once to 3 times per day, or once or 2 to 5 times per 2 or 3 days, preferably once to 3 times per 2 or 3 days. This is carried out for, for example, 1 to 60 days, preferably 2 to 30 days. When the ultrasonic irradiation is within the above range, the solid state 226 From Ra-containing materials 226 Efficiently extract Ra, 226 Ra can be adsorbed onto a support (i).

[0046] Although it depends on the frequency or the number of times of irradiation, the ultrasonic irradiation time per irradiation is, for example, 10 seconds to 1 hour, preferably 1 minute to 45 minutes, and more preferably 15 minutes to 45 minutes. The total ultrasonic irradiation time is, for example, 0.1 hours or more, preferably 0.5 to 50 hours, more preferably 0.5 to 20 hours, and even more preferably 0.5 to 10 hours. When the irradiation time is within the above range, the solid state 226 From Ra-containing materials 226 Efficiently extract Ra, 226 Ra can be adsorbed onto a support (i).

[0047] The recovery method (X) includes, after the step (A1), a step (A2) of separating the carrier (i) from the treatment liquid, and recovering the carrier (i) separated in the step (A2) using an acid. 226 It is preferable to include a step (A3) of eluting Ra.

[0048] <Process (A2)> In step (A2), in step (A1), 226 The carrier (i) on which Ra is adsorbed is separated from the treatment liquid. The method for separation is not particularly limited, and for example, it can be performed by filtration using a membrane filter or the like. 226 The carrier (i) with Ra adsorbed thereon can be collected on a filter and separated from the treatment solution. When the carrier (i) is packed in a bag or pack, the carrier (i) can be separated from the treatment solution by lifting the bag or pack filled with the carrier (i) using tweezers or the like.

[0049] <Process (A3)> In step (A3), 226 Using acid, Ra was adsorbed on the carrier (i). 226 Specifically, for example, an acid is passed through the carrier (i) or the carrier (i) is immersed in an acid to elute Ra adsorbed on the carrier (i). 226 Ra can be eluted.

[0050] The acid is adsorbed on the carrier (i). 226There are no particular limitations on the solvent as long as it can dissolve Ra into ions, but it is preferably at least one selected from the group consisting of hydrochloric acid and nitric acid. 226 The concentration of the acid is preferably 0.01 to 10 mol / L, more preferably 0.1 to 5 mol / L, and even more preferably 0.3 to 2 mol / L, from the viewpoints of efficiently eluting Ra from the carrier and efficiently removing anions derived from the acid in a subsequent step.

[0051] It is preferable that the steps (A2) and (A3) are carried out after repeating the step (A1) multiple times. 226 Ra can be efficiently recovered. The number of times step (A1) is repeated is not particularly limited, but step (A2) and step (A3) are preferably performed after step (A1) has been performed 2 to 10 times, and more preferably after step (A1) has been performed 3 to 5 times.

[0052] In the recovery method (X), it is preferable to carry out the following steps (A4) and (A5) after carrying out the step (A3). Step (A4): A step of filtering the eluate obtained in Step (A3) Step (A5): A step of adjusting the pH of the filtrate obtained in step (A4) and then filtering it through a filter.

[0053] <Process (A4)> In step (A4), the hydroxybenzoate obtained in step (A3) is 226 The Ra-containing eluate can be filtered to remove substances that precipitate under acidic conditions. The filter used for filtration is not particularly limited, and examples of the material include fluorocarbon, cellulose, nylon, polyester, and hydrocarbon filters. The pore size of the filter can be appropriately selected according to the target cleanliness, but is preferably 1 μm or less, and more preferably 0.5 μm or less. The filtration method may involve passing the solution through it only once, but it is more preferable to perform filtration multiple times.

[0054] <Process (A5)> In step (A5), the hydroxybenzoate obtained in step (A4) is 226 After adjusting the pH of the filtrate containing Ra, filtration can be performed to remove substances that precipitate under pH conditions different from those in step (A3). The filter used for filtration can be appropriately selected based on the same criteria as in step (A4). In step (A5), it is preferable to adjust the pH of the filtrate to alkaline conditions using ammonia, which makes it possible to remove substances that precipitate under alkaline conditions.

[0055] It is preferable to repeat steps (A1) to (A5) multiple times. 226 Ra can be efficiently recovered. There are no particular restrictions on the number of repetitions, but steps (A1) to (A5) are preferably carried out 2 to 10 times, and more preferably 3 to 5 times.

[0056] <Other processes> The recovery method (X) may include a step of washing the carrier (i) between steps (A2) to (A5). Specifically, water may be passed through the carrier (i). By doing so, the recovered 226 Reduce the proportion of impurities in the solution containing Ra, and 226 It can increase the recovery rate of Ra.

[0057] [ 226 Ra solution manufacturing method] It is one aspect of the present invention 226 The method for producing the Ra solution (hereinafter also referred to as "production method (Y)") is a method for producing a solid Ra solution. 226 The Ra-containing substance and the carrier (i) are immersed in a treatment liquid, and then the treatment liquid is irradiated with ultrasonic waves (step (A1)), the carrier (i) is separated from the treatment liquid (step (A2), and the carrier (i) separated in step (A2) is extracted with an acid. 226 The method (Y) includes a step (A3) of eluting Ra. 226 Ra solution, 226 This is called Ra solution (α). 226Ra solution (α) is highly pure 226 Since it contains Ra, it can be used for various purposes, 226 It is preferably used for manufacturing Ra targets.

[0058] In the production method (Y), it is preferable to carry out the following steps (A4) and (A5) after carrying out the step (A3). Step (A4): A step of filtering the eluate obtained in Step (A3) Step (A5): A step of adjusting the pH of the filtrate obtained in step (A4) and then filtering it through a filter. Steps (A1) to (A5) in the production method (Y) can be carried out in the same manner as steps (A1) to (A5) in the production method (X) described above.

[0059] [ 225 Ac solution manufacturing method] It is one aspect of the present invention 225 The manufacturing method of Ac solution is manufacturing method (Y). 226 A step (B1) of obtaining a Ra solution (α); 226 From Ra solution (α) 225 and a step (B2) of preparing an Ac solution. In step (B1), the production method (Y) is carried out, 226 Ra solution (α) is obtained. In step (B2), 226 From Ra solution (α) 225 Prepare Ac solution. 225 The method for producing the Ac solution is not particularly limited, but examples thereof include the following method.

[0060] 226 An electrodeposition solution was prepared using the Ra solution (α), and the electrodeposition solution was used 226 By electrodepositing Ra onto the substrate, 226 A Ra target is manufactured. 226 The Ra target is irradiated with at least one kind of charged particles, photons, and neutrons using an accelerator to generate a nuclear reaction. 225 Ac is generated. 226 The Ra target is dissolved in an acid solution.225 Contains Ac ions 225 Obtain Ac solution. 226 When the electrodeposition solution is prepared using the Ra solution (α), the treatment solution in step (B1) preferably does not contain an alkali metal salt.

[0061] The aspects of the present invention described above based on the embodiments include the following technical ideas. [1] Solid 226 A Ra-containing material; 226 The method includes a step (A1) of immersing a carrier having a function of adsorbing Ra ions in a treatment liquid and then irradiating the treatment liquid with ultrasonic waves. 226 How to collect Ra. [2] The solid 226 [1] The Ra-containing material is at least one selected from the group consisting of uranium slag and radium sources. 226 How to collect Ra. [3] The carrier is 226 [1] or [2], which is capable of exchanging Ra ions. 226 How to collect Ra. [4] The carrier according to any one of [1] to [3], wherein the carrier contains an iminodiacetic acid group. 226 How to collect Ra. [5] Further, a step (A2) of separating the carrier from the treatment liquid, and a step (A2) of removing the carrier from the treatment liquid using an acid. 226 [4], comprising a step (A3) of eluting Ra. 226 How to collect Ra. [6] The method according to [5], wherein the acid is at least one selected from the group consisting of hydrochloric acid and nitric acid. 226 How to collect Ra. [7] Solid 226 A Ra-containing material; 226 a step (A1) of immersing a carrier having a function of adsorbing Ra ions in a treatment liquid and then irradiating the treatment liquid with ultrasonic waves; A step (A2) of separating the carrier from the treatment liquid; and The carrier separated in the step (A2) is treated with an acid. 226Step (A3) of eluting Ra Including, 226 How to make Ra solution. [8][7] 226 The manufacturing method of Ra solution 226 A step (B1) of obtaining a Ra solution; 226 From Ra solution 225 and a step (B2) of preparing an Ac solution; 225 How to make Ac solution. [9] The method for recovering 226Ra according to [5] or [6], wherein the step (A1) is repeated multiple times, and then the step (A2) and the step (A3) are carried out.

[10] After carrying out the step (A3), the method according to any one of [5], [6] and [9], further comprising carrying out the following steps (A4) and (A5): 226 How to collect Ra. Step (A4): A step of filtering the eluate obtained in the step (A3) Step (A5): A step of adjusting the pH of the filtrate obtained in step (A4) and then filtering it through a filter.

[11] The method according to

[10] , wherein in the step (A5), the pH of the filtrate is adjusted to an alkaline condition using ammonia. 226 How to collect Ra. [Example]

[0062] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0063] Example 1 All of the following procedures were carried out in a glove box. A radium source (3 mm in diameter, 20 mm in length) containing an unknown chemical form of radium was cut with nippers into 5-6 small pieces. Chelex-100 resin (Bio-Rad, particle size: 50-100 mesh, ion type: Na type, amount used: 1 mL) was dissolved in NH4 +The mold was placed in a bag (polyethylene and polypropylene mesh, 2 cm square tetrahedron) and closed. The bag containing Chelex-100 resin and a small radium source piece were placed in a 100 mL glass bottle, and 0.5 mL of 14% aqueous ammonia (Nacalai Tesque, Inc.) was added to adjust the pH to 10. The bottle was placed in a water bath using a water bath-type ultrasonic generator (SND Corporation, US-610, output 110 W, frequency 44 kHz) and exposed to ultrasound for 30 minutes. Ultrasonic exposure was repeated multiple times, once every 2–3 days. After ultrasound exposure, the bottle was left at room temperature until the next ultrasound exposure. The bag containing Chelex-100 resin was removed with tweezers and placed in a glass bottle containing 15 mL of 0.7 M nitric acid (first bottle). After a few days, the bag containing Chelex-100 resin was removed with tweezers from the glass bottle containing 15 mL of 0.7 M nitric acid and placed in another glass bottle containing 15 mL of 0.7 M nitric acid (the second bottle). After a few days, the bag containing Chelex-100 resin was removed with tweezers from the second glass bottle containing 15 mL of 0.7 M nitric acid. The eluates from the first and second bottles were combined and 226 This was named Ra-containing solution (a-1). The pH was 0 to 2.

[0064] 226 The Ra-containing solution (a-1) was filtered through a membrane filter (DLL Filter, manufactured by NMP, pore size 0.2 μm) to remove acidic precipitates. 226 This was named Ra-containing solution (a-2). 226 14% ammonia water (prepared by diluting ammonia water (Nacalai Tesque, Inc., 02512-95)) was added to the Ra-containing solution (a-2) until it became alkaline (pH 9 to 11), and then the solution was filtered through a membrane filter to remove basic precipitates. 226 This was named Ra-containing solution (a-3).

[0065] Chelex 100 (amount used: 3 mL) with NH4 +The converted product was packed into a medical tube (manufactured by Hakkosha Co., Ltd., 3.2 × 4.4 × 500 mm (4 mL)) with an inner diameter of 3.2 mm, an outer diameter of 4.4 mm, and a length of 50 cm. Next, anion exchange resin (Monosphere 550A) (manufactured by Fujifilm Wako Chemical Co., Ltd., particle size: 590±50 μm mesh, ion type: OH type, amount used: 16 mL) was washed with water and then packed into a medical tube (manufactured by Hakkosha Co., Ltd., 3.2 × 4.4 × 500 mm (4 mL)) with an inner diameter of 3.2 mm, an outer diameter of 4.4 mm, and a length of 50 cm, and connected next to the tube filled with Chelex 100. 226 The Ra-containing solution (a-3) was passed through Chelex 100 and an anion exchange resin. The passed-through liquid was discarded. Then, 10 mL of 1 mol / L nitric acid and then 10 mL of water were passed through Chelex 100 and anion exchange resin at a flow rate of 1 to 2 mL / min, and 20 mL of the eluate was purified. 226 This was named Ra-containing solution (a-4).

[0066] The radium source pieces that had been treated once in the above process were subjected to re-extraction using the following procedure. A bag containing Chelex-100 resin was added to a 100 mL glass bottle containing the radium source pieces, and ultrasonic irradiation was performed in the same manner as above. The bag containing Chelex-100 resin was then removed and placed in a glass bottle containing 15 mL of 0.7 M nitric acid (first bottle). After a few days, the bag containing Chelex-100 resin was removed with tweezers from the first glass bottle containing 15 mL of 0.7 M nitric acid and placed in another glass bottle containing 15 mL of 0.7 M nitric acid (second bottle). After a few days, the bag containing Chelex-100 resin was removed with tweezers from the second glass bottle containing 15 mL of 0.7 M nitric acid. After elution with 15 mL of 0.7 M nitric acid, purification 226 The same procedure was repeated to obtain Ra-containing solution (a-4). The Chelex-100 resin bag and ammonia water were reused. The re-extraction procedure was repeated twice until radioactivity was no longer detected in the 100 mL glass bottle containing the radium source fragments.

[0067] purification226 The radioactivity of the Ra-containing solution (a-4) was measured using a germanium semiconductor detector. In addition, the residual amount of Chelex-100 resin, radium source chips, materials (membrane filters, anion exchange resin, plastic equipment, glassware), and waste liquid was also measured. 226 To investigate the distribution of Ra, radioactivity was measured using a germanium semiconductor detector. 226 The mass balance of Ra was calculated, and the results are shown in Table 1. The same procedure was repeated three times, so the radioactivity measurement value is the total value of the three measurements.

[0068] [Table 1]

[0069] In Table 1, the radioactivity of the radium source before the start of the experiment was calculated using the following formula (1). Radium source before the experiment (calculated value) = Purification 226 Ra-containing solution (a-4) + Residues on the radium source + Residues on Chelex 100 resin after elution + Residues on materials + Wastewater... (1)

[0070] 226 Ra recovery rate (purification 226 The Ra-containing solution (a-4) / radium source before the experiment × 100) was 99%. 226 Ra loss rate (remaining on Chelex 100 resin after elution / purification 226 The Ra-containing solution (a-4) × 100) was 1%.

[0071] Comparative Example 1 All of the following work was carried out inside a glove box. A radium source (3 mm diameter, 20 mm length) whose chemical form of the radium contained was unknown was cut with nippers into 5-6 small pieces. A needle was used to scoop out the contents from the small radium source pieces. Since radium sulfate is often used in old radium sources, it was predicted that the chemical form of the radium contained was radium sulfate. Therefore, it was decided to recover the radium by heating it in an aqueous sodium carbonate solution.

[0072] The excavated contents of the radium source were placed in a glass bottle, and 2 mL of 1.5 M sodium carbonate (Nacalai Tesque, Inc., 31311-25, prepared by dissolving sodium carbonate in water) was added. The mixture was then heated at 80°C for 1 hour. The contents of the bottle were filtered through a membrane filter, and the filtrate was designated as waste liquid (b-1). The residue remaining on the filter was dissolved in 10 mL of 1 M hydrochloric acid (Nacalai Tesque, Inc., 18429-15, prepared by diluting hydrochloric acid), but some remained. This residue (presumably radium sulfate) was designated as residue (b-2). The solution in 1 M hydrochloric acid was filtered through a membrane filter to remove acidic precipitates. 14% ammonia water (Nacalai Tesque, Inc., 02512-95, prepared by diluting ammonia water) was added to the filtrate until it became alkaline (pH 9-11), and then the solution was filtered through a membrane filter to remove basic precipitates. 226 A Ra-containing solution was obtained.

[0073] Chelex 100 (amount used: 3 mL) with NH4 + The converted product was packed into a medical tube (manufactured by Hakkosha Co., Ltd., 3.2 × 4.4 × 500 mm (4 mL)) with an inner diameter of 3.2 mm, an outer diameter of 4.4 mm, and a length of 50 cm.

[0074] Next, anion exchange resin (Monosphere 550A) (manufactured by Fujifilm Wako Chemical Co., Ltd., particle size: 590±50 μm mesh, ion type: OH type, amount used: 16 mL) was washed with water and then packed into a medical tube (manufactured by Hakkosha Co., Ltd., 3.2 × 4.4 × 500 mm (4 mL)) with an inner diameter of 3.2 mm, an outer diameter of 4.4 mm, and a length of 50 cm, and connected next to the tube filled with Chelex 100. After removing the basic precipitate, 226 The Ra-containing solution was passed through Chelex 100 and an anion exchange resin. Then, 10 mL of 1 mol / L nitric acid and then 10 mL of water were passed through the Chelex 100 and anion exchange resin at a flow rate of 1 to 2 mL / min, and 20 mL of the eluate was purified. 226 This was named Ra-containing solution (b-3).

[0075] The radium source fragments used in the above process were re-extracted using the following procedure. The radium source fragments were placed in a glass bottle again and heated in 1.5M sodium carbonate at 80°C for 1 hour. 226 The same procedure as above was repeated to obtain the Ra-containing solution (b-3). The re-extraction procedure was repeated four times.

[0076] purification 226 The radioactivity of the Ra-containing solution (b-3) was measured using a germanium semiconductor detector. The residual amount of the waste liquid (b-1), residue (b-2), and materials (membrane filters, anion exchange resins, plastic equipment, and glassware) was also measured. 226 To investigate the distribution of Ra, radioactivity was measured using a germanium semiconductor detector. 226 The mass balance of Ra was calculated, and the results are shown in Table 2. Note that the same procedure was repeated five times, so the radioactivity measurement value is the total value for the five times.

[0077] [Table 2]

[0078] In Table 2, the radioactivity of the radium source before the start of the experiment was calculated using the following formula (2). Radium source before the experiment (calculated value) = Residuals in the radium source + waste liquid (b-1) + residue (b-2) + refinement 226 Ra-containing solution (b-3) + residue on materials ···(2)

[0079] 226 Ra recovery rate (purification 226 The Ra-containing solution (b-3) / radium source before the experiment × 100) was 21%. 226 Ra loss rate (waste liquid (b-1) + residue (b-2) / refinement 226 The Ra-containing solution (b-3) × 100) was 6%.

[0080] Example 2 An old radium needle (1.6 mm diameter, 25 mm length, 226 The sample (containing 37-74 MBq (1-2 mCi) of Ra radioactivity) was cut into 5-6 small pieces using nippers (for 1 / 16" stainless steel tubes). These small pieces were placed in a 50 mL glass bottle (Duran Wheaton Kimble) with a propylene screw cap. Chelex-100 resin (Bio-Rad, particle size: 50-100 mesh, ion type: Na type, amount used: 3 mL) was added to the bottle with NH4 + The converted product was mixed with 7 mL of water and 28% aqueous ammonia to adjust the pH to 10. The glass bottle was placed in a treatment tank (water bath) of a water bath-type ultrasonic generator (US-350S, manufactured by SND Corporation, output 40 W, frequency 38 kHz) and ultrasonicated for 5 minutes. Ultrasonic irradiation was carried out approximately 1 to 3 times per day. This series of ultrasonic irradiation and leaving it for several days was repeated for one week. After ultrasonic irradiation, the glass bottle was left to stand at room temperature until the next ultrasonic irradiation. The contents of the glass bottle were transferred to an empty cartridge (Bond Elut, 5 mL, Agilent The Chelex-100 resin was filtered off. 5 mL of 1 M hydrochloric acid was added, followed by 10 mL of purified water. 226 Ra was eluted. 226 This was named Ra-containing solution (c-1). The pH was estimated to be between 0 and 1.

[0081] 226 The Ra-containing solution (c-1) was passed through an anion exchange resin (Monosphere 550A) (manufactured by Fujifilm Wako Chemical Co., Ltd., particle size: 590±50 μm mesh, ion type: OH type, amount used: 16 mL) to remove chloride ions. Subsequently, 10 mL of purified water was passed through the anion exchange resin to wash it. This eluate was purified. 226 This was named Ra-containing solution (c-1). 226 The Ra-containing solution (c-1) was concentrated under reduced pressure at 130°C to obtain dried radium hydroxide. 226 Ra was recovered.

[0082] purification 226The radioactivity of the Ra-containing solution (c-1) was measured using a germanium semiconductor detector. The residual amount of Chelex-100 resin, radium needle fragments, and materials (cartridges, anion exchange resins, and plastic utensils) was also measured. 226 To investigate the distribution of Ra, radioactivity was measured using a germanium semiconductor detector. 226 The mass balance of Ra was calculated. 226 The Ra recovery rate was approximately 30 to 50%.

[0083] The residue remaining on the filtered Chelex-100 resin 226 To recover Ra, the filtered Chelex-100 resin was placed in a 50 mL glass bottle with a propylene screw cap, and 7 mL of water and aqueous ammonia were added to adjust the pH to 10. The bottle was left standing for one month without ultrasonic irradiation. After filtering the Chelex-100 resin using an empty cartridge, the same procedures were carried out as above until dried radium hydroxide was obtained. 226 Purification of Ra-containing solution 226 This was named Ra-containing solution (c-2).

[0084] purification 226 The Ra-containing solution (c-2) was purified. 226 The radioactivity of the Ra-containing solution (c-1) was measured using a germanium semiconductor detector. 226 The Ra recovery rate was 100%.

Claims

1. solid 226 an Ra-containing material; 226 The method includes a step (A1) of immersing a carrier having a function of adsorbing Ra ions in a treatment solution, and then irradiating the treatment solution with ultrasonic waves. 226 Method for recovering Ra.

2. The solid 226 2. The method according to claim 1, wherein the Ra-containing material is at least one selected from the group consisting of uranium slag and a radium source. 226 Method for recovering Ra.

3. The carrier is 226 3. The method according to claim 1, wherein Ra ions can be exchanged. 226 Method for recovering Ra.

4. The carrier according to any one of claims 1 to 3, wherein the carrier comprises an iminodiacetic acid group. 226 Method for recovering Ra.

5. Further, a step (A2) of separating the carrier from the treatment liquid, and a step (A3) of removing the carrier from the treatment liquid using an acid. 226 The method according to any one of claims 1 to 4, further comprising the step (A3) of eluting Ra. 226 Method for recovering Ra.

6. 6. The method according to claim 5, wherein the acid is at least one selected from the group consisting of hydrochloric acid and nitric acid. 226 Method for recovering Ra.

7. solid 226 an Ra-containing material; 226 a step (A1) of immersing a carrier having a function of adsorbing Ra ions in a treatment liquid and then irradiating the treatment liquid with ultrasonic waves; A step (A2) of separating the carrier from the treatment liquid; and The carrier separated in the step (A2) is treated with an acid. 226 Step (A3) of eluting Ra Including, 226 Method for producing Ra solution.

8. The method according to claim 7 226 By the method of manufacturing Ra solution 226 A step (B1) of obtaining an Ra solution; 226 From Ra solution 225 and (B2) preparing an Ac solution. 225 Method for producing Ac solution.

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