A th / radium generator containing natural thorium and a method for producing 224Ra therefrom

Abstract

This invention discloses a Th / Ra generator containing natural thorium and its production. 224 The Ra method. The generator of this invention includes a cation exchange resin column and bottles I to VI; wherein bottle I is filled with the stock solution; bottle III is filled with deionized water; bottle IV is filled with 4.0–6.0 M nitric acid; bottles II, V, and VI are empty; bottle V is a specially designed collection bottle with an extraction resin column at its opening for collection. 224 Ra. The method of the present invention includes the following steps: 1) using a mixture containing 228 1) A natural thorium mixture of Th and Ra was concentrated to obtain a concentrate, and then the pH of the system was adjusted to serve as the packing stock solution for the Th / Ra generator; 2) The stock solution was passed through a cation exchange resin column to obtain a cation exchange resin column loaded with thorium. 224 Ra, and collect the eluent from the original solution for later use; 3) Elute the cation exchange resin column with inorganic acid. 224 Ra, then the eluent is collected using a special collection bottle to obtain... 224 Ra. This invention enables the separation, purification, and recycling of [product name]. 224 Ra, to overcome 228 Th / 224 The Ra generator has a stringent loading process to avoid the radioactive risks associated with handling tons of natural thorium.

Description

Technical Field

[0001] This invention belongs to the field of medical radioisotope generator development, and relates to a Th / Ra generator containing natural thorium and its production. 224 Ra's method. Background Technology

[0002] 224 Ra has a half-life of 3.66 days and emits alpha particles with an average energy of 5.68 MeV, making it a viable alternative. 223 Ra is a potential medical isotope for treating various metastatic cancers, such as 224 Ra-labeled CaCO3 can treat ovarian cancer (see Translational Oncology (2018) 11:259–267). Meanwhile, 224 Ra's daughter 212 Pb and 212 Bi has also been confirmed by numerous literature reports to be a valuable targeted therapy for alpha nuclides, therefore 224 Ra can be used for design and filling. 212 Pb / 212 Bi is the direct raw material for Bi generators.

[0003] Currently, isotopes have not yet been prepared. 224 Effective methods for Ra, whose main source is from natural sources 232 Th(T 1 / 2 =1.405×10 10 y) decay to 228 Ra(T 1 / 2 =5.75y), and then the daughter body was obtained by separation. 228 Ac(T 1 / 2 =6.15h), and then decays to 228 Th(T 1 / 2 =1.91y) is needed to separate again 224 Ra. Among them, due to... 232 The extremely long half-life of thorium necessitates processing tons of natural thorium using liquid / liquid extraction or precipitation steps each time to produce micro-housing quantities. 224 Ra, and can only meet the needs of a few injection treatments. Furthermore, in the entire decay chain, the indirect parent... 228 The Ra content is much higher than that of the product, so it needs to be separated and removed in advance to enrich a large amount of Ra. 228 Only after Ac can it be achieved 228 Th / 224 The loading of the Ra generator. It is evident that the entire separation process is complex and cumbersome, with extremely high production costs. Summary of the Invention

[0004] The purpose of this invention is to provide a Th / Ra generator containing natural thorium and its production. 224 The Ra method. This invention can overcome... 228 Th / 224 The Ra generator is meticulously packed to avoid the radioactive risks associated with handling tons of natural thorium, requiring separation, purification, and recycling. 224 Ra.

[0005] This invention provides a Th / Ra generator containing natural thorium for production. 224 The method of Ra includes the following steps: 1) using a method containing 228 The natural thorium mixture of Th was concentrated to obtain a concentrate, and then the pH of the system was adjusted to serve as the packing stock solution for the Th / Ra generator.

[0006] 2) Pass the stock solution through a cation exchange resin column to obtain a solution loaded on the cation exchange resin column. 224 Ra, and collect the leachate from the original solution for later use;

[0007] 3) The column loaded with cation exchange resin is eluted with inorganic acid. 224 Ra, then the eluent is collected using a special collection bottle to obtain... 224 Ra;

[0008] The specially designed collection bottle has an extraction resin column installed at its mouth.

[0009] In this invention, the mouth of the specially designed collection bottle is equipped with an extraction resin column to purify and remove Th from the eluent.

[0010] In the above method, the one containing 228 The natural thorium mixture of Th was selected from the solution after high-energy proton irradiation of metallic Th or ThO2 targets, or enriched with thorium. 228 Ac / 228 The mixture was also contaminated with natural thorium.

[0011] The filling stock solution 228 Th and 232 The specific activity of Th is greater than 3.0 kBq / g.

[0012] In the above method, if the system is turbid after concentration as described in step 1), the method further includes the steps of adding acid and water to dissolve it.

[0013] The acid and water dissolution process is as follows: 0.2-2.0 mL of concentrated sulfuric acid and 1-2 drops of 40% hydrofluoric acid are added to the concentrated solution and heated to 60-80°C. The solution is kept at this temperature for 20-80 minutes to dissolve. Then, 4-20 mL of deionized water is added and stirred at room temperature until it is completely dissolved and clarified.

[0014] The volume ratio of the concentrated solution to the added concentrated sulfuric acid can be 0.25 to 40.0 mL: 1.

[0015] In this invention, the room temperature is common knowledge in the field and generally refers to 10-30°C.

[0016] In the above method, step 1) involves adjusting the pH of the system to 0.5–3.0.

[0017] In the above method, the pH adjustment of the system in step 1) is as follows: add 0.3-0.5M ammonium sulfate solution, and then adjust the pH using concentrated ammonia.

[0018] The volume of the 0.3–0.5 M ammonium sulfate solution and the volume containing 228 Th natural thorium mixture 232 The mass ratio of Th is 30-50 mL / g.

[0019] In the above method, the flow rate of the stock solution through the cation exchange resin column in step 2) can be 0.5 to 5.0 mL / min.

[0020] In the above method, in step 3), the inorganic acid is nitric acid, specifically 4.0–6.0 M nitric acid;

[0021] The volume ratio of the inorganic acid to the cation exchange resin column can be 3 to 5:1, specifically 4:1.

[0022] The extraction resin column includes a UTEVA resin column;

[0023] The cation exchange resin column includes AG50W-X8 (specifically, 100-300 mesh) cation exchange resin;

[0024] The volume ratio of the extraction resin column to the cation exchange resin column can be 0.35 to 0.55 mL / mL.

[0025] In the above method, step 3) involves rinsing the column loaded with cation exchange resin using an inorganic acid. 224 Before and after Ra, deionized water was used for rinsing, and the loading mode of the cation resin column was adjusted to ensure the initial state of the generator was reset.

[0026] The volume ratio of the deionized water to the cation exchange resin column can be 4 to 6:1, specifically 5:1.

[0027] In the above method, after the leachate of the original solution is allowed to stand and equilibrate for 12-28 days, steps 2)-3) are repeated to generate the product. 224 Ra.

[0028] In the above method, the generation 224The total period of the Ra cycle can be 0.2 to 10 years.

[0029] In this invention, a Th / Ra generator containing natural thorium includes a cation resin column, bottle I, bottle II, bottle III, bottle IV, bottle V, and bottle VI;

[0030] The cation resin column has inlet A and inlet B on its inlet pipeline, a peristaltic pump on the inlet pipeline, and one-way valves on the inlet pipelines between inlet A, inlet B and the cation resin column to control the flow of material into the cation resin column; and outlet C on the outlet pipeline of the cation resin column.

[0031] Bottle I, filled with the stock solution, is located within the lead-shielded area and is used to [dissolve / protect / protect / ensure / control] the [solution / containment] solution. 224 Ra is loaded onto the cation exchange resin column;

[0032] Bottle III is filled with deionized water for use in rinsing the column loaded with cation exchange resin using inorganic acid. 224 Before and after Ra, deionized water was used for rinsing, and the loading mode of the cation resin column was adjusted to ensure the initial state of the generator was reset.

[0033] Bottle IV is filled with 4.0–6.0 M nitric acid for rinsing the column loaded with cation exchange resin. 224 Ra;

[0034] Bottles II, V, and VI are all empty; bottle II is used to receive the eluent from the stock solution for reuse as raw material; bottle V is a specially designed collection bottle with an extraction resin column at its opening for use at outlet C; bottle V is used to collect... 224 Ra; Bottle VI is used to receive deionized water rinsing solution.

[0035] In this invention, the cation resin column may not require shielding and may simply be located within the protected area.

[0036] In the aforementioned Th / Ra generator containing natural thorium, the volume ratio of the extraction resin column to the cation exchange resin column is 0.35–0.55 mL / mL.

[0037] The extraction resin column includes a UTEVA resin column;

[0038] The cation exchange resin column includes AG50W-X8 (specifically, 100-300 mesh) cation exchange resin.

[0039] In this invention, a Th / Ra generator containing natural thorium is used to produce... 224 The operation method of Ra includes the following steps:

[0040] (1) The initial state of the Th / Ra generator containing natural thorium is as follows: the peristaltic pump and all check valves are closed; all inlet and outlet ports are empty; bottle I is located in the lead shielding area; bottle III contains deionized water; bottle IV contains 4.0-6.0M nitric acid; bottles II, V, and VI are empty;

[0041] (2) Connect the outlet C to bottle II, immerse the inlet A to the bottom of bottle I, turn on the peristaltic pump and open valve A, and the original liquid in bottle I can be collected into bottle II by passing through the cation exchange resin column in the protection zone;

[0042] The cation exchange resin column used in the generator protection zone can be AG50W-X8 (100-300 mesh) cation exchange resin, and the ratio of the volume of the stock solution in bottle I to the volume of the cation exchange resin column can be 8.0-25 mL / mL.

[0043] The flow rate can be controlled using a peristaltic pump, specifically ranging from 0.5 to 5.0 mL / min;

[0044] (3) When no liquid droplets flow out of outlet C, replace bottle VI, close valve A, rename empty bottle I as bottle II and remove it for later use, and place the original bottle II in the lead-shielded area and rename it as bottle I.

[0045] (4) Connect the inlet B to bottle III, open valve B, and after 4 to 6 times the volume of the cation exchange resin column of solution has flowed out, remove bottle III.

[0046] (5) When no more droplets flow out of outlet C, switch to bottle V and inlet B to bottle IV. After 3 to 5 times the volume of the cation exchange resin column has flowed out, remove bottle IV.

[0047] (6) When no more liquid droplets flow out of outlet C for the third time, switch to bottle VI again and connect inlet B to bottle III. After 4 to 6 times the column volume of solution has flowed out, remove bottle III.

[0048] (7) When no liquid droplets flow out of outlet C for the fourth time, remove bottle VI, turn off the peristaltic pump and all check valves, and restore the Th / Ra generator to the initial state described in step (1) above.

[0049] In the above method, after each use, bottle V needs to be refilled with new UTEVA resin, or the special cap of the collection bottle V needs to be replaced for future use.

[0050] The solution collected in bottle V in step (5) of the above method is a solution containing 4.0–6.0 M nitric acid. 224 Ra product; Bottle VI collects acidic waste liquid containing a small amount of matrix Th.

[0051] In the above method, after the renamed bottle I has been in static equilibrium for 12 to 28 days (but not limited to 12 to 28 days), steps 2) to 7) of the above production method can be repeated to produce the product in a cyclical manner. 224 Ra products.

[0052] In the above method, based on the results obtained in each cycle of the Th / Ra generator... 224 Whether the dosage of Ra products meets the needs of relevant research and application determines whether cyclical production operations should be carried out; theoretically, the total cycle can be 0.2 to 10 years, but is not limited to this.

[0053] The present invention has the following beneficial effects:

[0054] 1. Use materials with high specific activity 228 Natural thorium mixtures, including but not limited to solutions from high-energy proton irradiation of metallic th or thO2 targets, can be concentrated, redissolved, and adjusted to a weakly acidic ammonium sulfate system for use as the packing stock solution, overcoming [the following limitations]. 228 Th / 224 The Ra generator is loaded with stringent requirements to avoid the radioactive risks associated with handling tons of natural thorium;

[0055] 2. Target product loaded onto a cation exchange resin column. 224 Ra, the ammonium sulfate system stock solution can be directly passed through and collected for use in the next production cycle, and can be continuously recycled and reused;

[0056] 3. Using a special design 224 Ra collection bottle, with a UTEVA resin column designed on the cap, allows for inorganic acid rinsing of the cation exchange resin column. 224 During Ra, purification removes trace amounts of impurity Th from the product;

[0057] 4. Rinse 224 Before and after Ra, the generator is rinsed with deionized water, the loading mode of the cation exchange resin column is adjusted, and the generator is reset to its initial state so that it can be used directly in the next cycle without redundant operation.

[0058] 5. A Th / Ra generator containing a large matrix of natural thorium can be used repeatedly for several years, and a simple, efficient, economical, and safe process can be established to meet the needs of isotope separation and purification in China. 224 Ra, and prepared in multiple cycles 224 The goal of Ra products. Attached Figure Description

[0059] Figure 1 This is a schematic diagram of a Th / Ra generator containing natural thorium.

[0060] Figure 1 The various markers are as follows:

[0061] 1-6 Bottles I, II, III, IV, V and VI; 7 Cationic resin column; 8 UTEVA resin column; 9 Inlet A; 10 Inlet B; 11 Outlet C; 12 Check valve A; 13 Check valve B; 14 Peristaltic pump; 15 Lead shielding area; 16 Protected area.

[0062] Figure 2 For the first preparation 224 γ-ray spectra of crude Ra product.

[0063] Figure 3 For cyclic preparation 224 γ-ray spectra of Ra products.

[0064] Figure 4 For cyclic preparation 224 α spectrum of Ra product. Detailed Implementation

[0065] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0066] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0067] like Figure 1 As shown, the present invention discloses a Th / Ra generator containing a large matrix of natural thorium, comprising a cation exchange resin column 7, bottle I 1, bottle II 2, bottle III 3, bottle IV 4, bottle V 5, and bottle VI 6. Bottle V 5 is a specially designed collection bottle, and its mouth is provided with an extraction resin column (including a UTEVA resin column 8).

[0068] The inlet line of the cation resin column 7 is equipped with inlet A9 and inlet B10, and a peristaltic pump 14 is installed on the inlet line. One-way valves A12 and B13 are respectively installed on the inlet lines between inlet A9, inlet B10 and the cation resin column 7 to control the flow of material into the cation resin column 7 in one direction. The outlet line of the cation resin column 7 is equipped with outlet C11. During use, the cation resin column 7 is placed within the protection zone 16.

[0069] Bottle I1 is filled with the stock solution and is located within lead-shielded area 15. It is used to convert the stock solution into liquid. 224 Ra is loaded onto the cation exchange resin column 7; bottle III3 contains deionized water for rinsing the cation exchange resin column with an inorganic acid. 224Before and after Ra, deionized water was used for rinsing, and the loading mode of the cation exchange resin column was adjusted to ensure the generator's initial state was reset. Bottle IV4 contained 4.0–6.0 M nitric acid, while bottles II2, V5, and VI6 were empty. Bottle II2 was used to receive the eluent from the original solution for reuse as raw material. Bottle V5 was a specially designed collection bottle with an extraction resin column at its opening for outlet C. Bottle V5 was used for collection. 224 Ra; Bottle VI6 is used to receive deionized water rinsing solution.

[0070] The Th-containing solution in bottle I1 (a pointed-bottom bottle) is the packing stock solution for this generator. The preparation process of the stock solution is as follows:

[0071] Contains high specific activity 228 The natural thorium mixture solution was concentrated to near dryness by heating. 0.2–2.0 mL of concentrated sulfuric acid and 1–2 drops of 40% hydrofluoric acid were added, and the mixture was heated to 60–80°C and kept at this temperature for 20–80 minutes to dissolve. Then, 4–20 mL of deionized water was added, and the mixture was stirred at room temperature until completely dissolved and clarified. Any remaining residue was removed by filtration. Next, 0.3–0.5 M ammonium sulfate solution was added, and the acidity of the solution was adjusted to pH 0.5–3.0 using concentrated ammonia. The solution was then transferred to flask I1 of the generator.

[0072] The volume of 0.3–0.5 M ammonium sulfate solution added is related to the volume of the mixed raw materials. 232 The mass ratio of Th can be 30-50 mL / g;

[0073] If the above-mentioned natural thorium raw material is still clear when concentrated to near dryness, the acid and water dissolution steps in step 1) can be omitted. Instead, 0.3-0.5M ammonium sulfate solution is added, and then concentrated ammonia water is used to adjust the pH to 0.5-3.0.

[0074] In this invention, the Th / Ra generator is used to specifically produce... 224 The Ra method includes the following steps:

[0075] 1) The initial state of the Th / Ra generator containing natural thorium is as follows: the peristaltic pump and all check valves are closed; all inlet and outlet ports are empty; bottle I1 is located in the lead shielding area; bottle III3 contains deionized water; bottle IV4 contains 4.0-6.0M nitric acid; bottles II2, V5, and VI6 are empty;

[0076] 2) Connect the outlet C11 to bottle II2 (pointed bottom bottle), immerse the inlet A9 to the bottom of bottle I1, turn on the peristaltic pump 14, and open the one-way valve A12. The original liquid in bottle I1 can be collected into bottle II2 by passing through the cation exchange resin column 7 in the protection zone 16.

[0077] The cation exchange resin column 7 used in the above-mentioned protected area 16 can be AG50W-X8 (100-300 mesh) cation exchange resin. The ratio of the volume of the original solution in bottle I to the volume of the cation exchange resin column can be 8-25 mL / mL.

[0078] A peristaltic pump was used to control the flow rate at 0.5–5.0 mL / min;

[0079] 3) When no more liquid droplets flow out of outlet C11, replace bottle VI6, close check valve A12, rename empty bottle I1 to bottle II2 and remove it for later use, and place the original bottle II2 in the lead-shielded area and rename it to bottle I1;

[0080] 4) Connect inlet B10 to bottle III3, open check valve B13, and after 5 times the volume of cation exchange resin column of solution has flowed out, remove bottle III.

[0081] 5) When no more droplets flow out of outlet C11, switch to bottle V5 and inlet B10 to bottle IV4. After 4 times the volume of the cation exchange resin column of solution has flowed out, remove bottle IV4.

[0082] The inlet of the above-mentioned bottle V is specially customized and contains an extraction resin column. The extraction resin used can be UTEVA (100-300 mesh). The ratio of the volume of the UTEVA resin to the volume of the cation exchange resin column in the above-mentioned protected area can be 0.35-0.55 mL / mL.

[0083] After each use, bottle V5 needs to be refilled with new UTEVA resin, or the bottle cap should be replaced with a new one for future use.

[0084] 6) When no more liquid droplets flow out of outlet C11 for the third time, switch to bottle VI6 again and connect inlet B10 to bottle Ⅲ3. After 5 column volumes of solution have flowed out, remove bottle Ⅲ3.

[0085] 7) When no liquid droplets flow out of outlet C11 for the fourth time, remove bottle VI6, turn off the peristaltic pump and all check valves, and restore the Th / Ra generator to the initial state described in step 1).

[0086] The solution in bottle V5 obtained in step 5) above contains 4.0–6.0 M nitric acid solution. 224 Ra product; Bottle VI6 contains acidic waste liquid containing a small amount of matrix Th;

[0087] After the renamed bottle I1 has been in static equilibrium for 12–28 days (but not limited to 12–28 days), steps 2)–7) of the above production method can be repeated to produce the product in a long cycle over several years. 224 Ra products.

[0088] Example 1

[0089] This embodiment illustrates how the residual liquid from a metal thorium target, cooled for 0.5–1.0 years after high-energy proton irradiation, is packed into the aforementioned Th / Ra generator, and how it is initially separated to obtain... 224 Feasibility of Ra crude products.

[0090] This example utilizes the HIRFL accelerator at the Institute of Modern Physics, Chinese Academy of Sciences (Lanzhou), to irradiate the target with a proton beam at an energy of 100 MeV and an average current of 24–42 nA. The resulting residual liquid in a metallic thorium target, containing most of the Ac element, was approximately 200 mL in volume. Analysis using a high-purity germanium gamma detector revealed that it primarily contained... 228 Th and 232 The decay products of Th. Meanwhile, based on the experimental records of the original target operation, it can be determined that the residual liquid mainly contains approximately 3.5 g of thorium ions. Other components are hydrogen ions, ammonium ions, sulfate ions, and nitrate ions, with a molar concentration approximately 4 to 15 times that of thorium ions.

[0091] This invention discloses a Th / Ra generator containing a large matrix of natural thorium, wherein the Th-containing solution in the conical-bottom flask I is the packing stock solution for the generator, and the preparation process of the stock solution is as follows:

[0092] The residual liquid of the metal thorium target, which had been cooled for 1.0 year after high-energy proton irradiation, was heated and concentrated to near dryness. 20 mL of deionized water was added directly, and the solution was stirred at room temperature until it was completely dissolved and clarified. Then, 120 mL of 0.4 M ammonium sulfate solution was added, and the acidity of the solution was adjusted to pH 2.0 using concentrated ammonia. The solution was then transferred to bottle I1 of the generator.

[0093] This invention utilizes the Th / Ra generator to specifically produce... 224 The Ra method includes the following steps:

[0094] 1) The initial state of the Th / Ra generator containing natural thorium is as follows: the peristaltic pump and all check valves are closed; all inlet and outlet ports are empty; bottle I1 is filled with the original solution and is located in the lead-shielded area; bottle III contains deionized water; bottle IV contains 5.0M nitric acid; bottles II, V, and VI are empty;

[0095] 2) Connect outlet C to conical bottom bottle II, immerse inlet A to the bottom of conical bottom bottle I, turn on the peristaltic pump, and open valve A12. The original solution in bottle I can be collected into bottle II by passing through the cation exchange resin column in the protection zone.

[0096] The cation exchange resin column used in the above-mentioned protected area can be AG50W-X8 (100-300 mesh) cation exchange resin with a volume of 10 mL.

[0097] A peristaltic pump was used to control the flow rate at 2.5 mL / min;

[0098] 3) When no more liquid droplets flow out of outlet C, replace bottle VI, close valve A, rename empty bottle I as bottle II and remove it for later use, and place the original bottle II in the lead-shielded area and rename it as bottle I;

[0099] 4) Connect inlet B to bottle III, open valve B, and after 50 mL of solution flows out, remove bottle III;

[0100] 5) When no more droplets flow out of outlet C, switch to bottle V and inlet B to bottle IV. After 40 mL of solution has flowed out, remove bottle IV.

[0101] The inlet of the above bottle V is specially customized and contains an extraction resin column. The extraction resin used can be UTEVA (100-300 mesh), and the volume of the UTEVA resin is 4 mL.

[0102] 6) When no more liquid drops flow from outlet C for the third time, switch to bottle VI again and connect inlet B to bottle III. After 50 mL of solution has flowed out, remove bottle III.

[0103] 7) When no liquid droplets flow out of outlet C for the fourth time, remove bottle VI, turn off the peristaltic pump and all check valves, and restore the Th / Ra generator to the initial state described in step 1) above.

[0104] This embodiment of the operation yielded 40 mL. 224 The crude Ra product solution had an activity of 11 kBq, a recovery rate greater than 94.6%, and a radioactive purity greater than 77.8%. Its gamma spectrum was obtained by referring to... Figure 2 Because the original solution contains a large amount of substances produced during the irradiation process. 228 Ra, resulting in the crude product 228 The Ra content is approximately 15.4%, therefore this crude product can be used for the preparation of... 212 Pb / 212 Bi's raw materials.

[0105] Example 2

[0106] This embodiment illustrates the cyclic operation steps of the above-mentioned large-matrix natural thorium Th / Ra generator, and the preparation of high-purity thorium every 10 to 28 days. 224 The feasibility of Ra products.

[0107] The Th / Ra generator containing natural thorium described in this invention needs to be checked and confirmed to be in the initial state before each use. After the solution in the renamed bottle I in Example 1 of this invention has been in static equilibrium for 28 days, steps 2) to 7) in the above production method can be repeated.

[0108] Bottle V in Example 1 above is replaced with new UTEVA resin after each use;

[0109] This embodiment repeats steps 2) to 7) four times, with each cycle lasting 21 to 28 days.

[0110] Each production cycle yielded 40 mL. 224 Ra product solutions, with activities of approximately 8–13 kBq, all showed recoveries greater than 95.2% and radionuclear purity greater than 98.3%, and can be used in related fields for the determination of radioactive nuclei. 224 The study of Ra, its γ spectrum is shown in Figure 3, and its α spectrum is shown in Figure 4. Figure 4 As shown.

Claims

1. A Th / Ra generator containing natural thorium. 224 The Ra method includes the following steps: 1) using a method containing 228 The natural thorium mixture of Th was concentrated to obtain a concentrate, and then the pH of the system was adjusted to serve as the packing stock solution for the Th / Ra generator, which was then placed in a lead-shielded area. The pH adjustment process in step 1) is as follows: add 0.3~0.5 M ammonium sulfate solution, and then adjust the pH using concentrated ammonia. 2) Pass the stock solution through a cation exchange resin column to obtain a solution loaded on the cation exchange resin column. 224 Ra, collect the leachate of the original solution and place it in a lead-shielded area for later use as the original solution; 3) The column loaded with cation exchange resin was eluted with inorganic acid. 224 Ra, then the eluent is collected using a special collection bottle to obtain... 224 Ra; The specially designed collection bottle has an extraction resin column installed at its mouth; In step 3), the extraction resin column is a UTEVA resin column; The cation exchange resin column is AG50W-X8 cation exchange resin; In step 3), the column loaded with cation exchange resin is eluted with inorganic acid. 224 Before and after Ra, the column was rinsed with deionized water to adjust the loading mode of the cation exchange resin column. After allowing the leachate from the original solution to stand at equilibrium for 12-28 days, repeat steps 2)-3) to generate the product. 224 Ra; The generation 224 The total period of the Ra cycle is 0.2 to 10 years.

2. The method according to claim 1, characterized in that, The containing 228 The natural thorium mixture of Th was selected from the solution after high-energy proton irradiation of metallic Th or ThO2 targets, or enriched with thorium. 228 Ac / 228 The mixture was also contaminated with natural thorium. The filling stock solution 228 Th and 232 The specific activity of Th is greater than 3.0 kBq / g.

3. The method according to claim 1 or 2, characterized in that, If the system is turbid after concentration as described in step 1), the process also includes adding acid and water to dissolve it. The acid and water dissolution process is as follows: 0.2-2.0 mL of concentrated sulfuric acid and 1-2 drops of 40% hydrofluoric acid are added to the concentrated solution and heated to 60-80 °C. The solution is kept at this temperature for 20-80 minutes. Then, 4-20 mL of deionized water is added and stirred until the solution is completely dissolved and clarified. The volume ratio of the concentrated solution to the added concentrated sulfuric acid is 0.25~40.0 mL:

1.

4. The method according to claim 1 or 2, characterized in that, The volume of the 0.3~0.5 M ammonium sulfate solution and the volume containing 228 Th natural thorium mixture 232 The mass ratio of Th is 30~50 mL / g.

5. The method according to claim 1 or 2, characterized in that, In step 2), the flow rate of the stock solution through the cation exchange resin column is 0.5~5.0 mL / min.

6. The method according to claim 1 or 2, characterized in that, In step 3), the inorganic acid is nitric acid; The volume ratio of the inorganic acid to the cation exchange resin column is 3~5:1; The volume ratio of the extraction resin column to the cation exchange resin column is 0.35~0.55 mL / mL.

7. The method according to claim 1 or 2, characterized in that, In step 3), the volume ratio of the deionized water to the cation exchange resin column is 4~6:

1.

8. The method according to claim 1, characterized in that: The method uses a Th / Ra generator containing natural thorium, comprising a cation resin column, bottle I, bottle II, bottle III, bottle IV, bottle V, and bottle VI; The cation resin column is provided with inlet A and inlet B on the inlet pipeline, and a peristaltic pump is provided on the inlet pipeline. One-way valves are respectively provided on the inlet pipelines between inlet A, inlet B and the cation resin column to control the flow of material into the cation resin column; outlet C is provided on the outlet pipeline of the cation resin column. Bottle I, filled with the stock solution, is located within the lead-shielded area and is used to [dissolve / protect / protect / ensure / control] the [solution / containment] solution. 224 Ra is loaded onto the cation exchange resin column; Bottle III is filled with deionized water for use in rinsing the column loaded with cation exchange resin using inorganic acid. 224 Before and after Ra, deionized water was used for rinsing, and the loading mode of the cation resin column was adjusted to ensure the initial state of the generator was reset. Bottle IV is filled with 4.0~6.0 M nitric acid for rinsing the column loaded with cation exchange resin. 224 Ra; Bottles II, V, and VI are all empty; bottle II is used to receive the eluent from the stock solution for reuse as raw material; bottle V is a specially designed collection bottle with an extraction resin column at its opening for use at outlet C; bottle V is used to collect... 224 Ra; Bottle VI is used to receive deionized water rinsing solution.

9. The method according to claim 8, characterized in that, The volume ratio of the extraction resin column to the cation exchange resin column is 0.35~0.55 mL / mL.

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