A method for preparing target particles for metal oxide irradiation

Abstract

The present invention relates to a method for preparing target particles for metal oxide irradiation, comprising the following steps: S1: preparing a precursor solution: preparing a complex solution of ammonium citrate, glycine, and urotropine in a ratio of 0.9-1.2:1:1, slowly dripping a metal nitrate solution into the complex solution to form a suspension, then dripping nitric acid into the suspension, observing the change in pH value, adjusting the pH to 3.5-2.7 until the liquid is clear, and forming a precursor solution; S2: hot silicone oil curing: dripping the precursor solution into hot silicone oil through a capillary tube, and forming gel microspheres after curing for a certain period of time; S3: n-octanol dehydration: collecting the gel microspheres and soaking them in n-octanol for dehydration treatment to further remove the moisture in the gel microspheres; S4: calcining: calcining the gel microspheres after dehydration treatment. Compared with the prior art, the present invention realizes the controllable gel preparation of multiple valence metal ions, forms oxide microspheres by sintering, and has high sphericity.

Description

Technical Field

[0001] The present invention relates to the technical field of metal oxide target material preparation technology, in particular to a method for preparing target material particles for metal oxide irradiation. Background Art

[0002] Placing a target in a reactor for irradiation, where the target material continuously captures neutrons, is an important method for producing isotopes. Therefore, the performance of the target pellets used in the reactor is crucial for achieving the conversion of nuclides and, in turn, the production of the relevant nuclides.

[0003] As a dispersed target, metal oxide target particles are required to possess high sphericity and monodispersity. Their preparation methods primarily fall into two categories: dry and wet methods. Powder granulation is the primary dry method for preparing spherical metal oxide particles. Among these various powder granulation methods, the most widely used method for preparing nuclear fuel or target microspheres is a powder grinding-prepressing-crushing-spheronization process, with research conducted in the United States, Europe, Japan, India, and my country. However, a drawback of this method is the tendency for fine dust to disperse during the preparation process, which limits its use, particularly for the preparation of microspheres containing radioactive materials. Another drawback is that dry methods cannot produce monodisperse fuel spheres with a micron size and exhibit poor sphericity. Wet methods for preparing metal oxide microspheres can effectively address these issues with dry methods.

[0004] Wet preparation has attracted much attention because it can directly convert the target metal element from liquid to solid state, thereby realizing the dust-free preparation of metal oxide microspheres. The process is as follows: first, a sol solution containing the target metal ions is prepared, and then sol droplets are obtained through a droplet preparation device. After gel reaction, gel balls are obtained, and metal oxide microspheres are obtained after washing, drying, and sintering. The preparation of sol droplets in this preparation process is a key step in achieving the control of the size of metal oxide spherical particles. At present, researchers are targeting divalent or tetravalent UO2 2+ , Pu 4+ ,Th 4+ and their analog materials Ce 4+ A lot of research has been carried out and significant results have been achieved.

[0005] Patent application CN116143500A discloses a method for preparing an indium oxide molybdenum praseodymium target, comprising the following steps: In2O3 powder, MoO3 powder, Pr6O 11The powder and dispersant are mixed and dispersed, and a binder is added after dispersion, and the mixture is wet-ball milled to obtain a slurry; the obtained slurry is spray-granulated to obtain fine powder and coarse powder after spray granulation, and the fine powder and coarse powder are mixed in a certain proportion to obtain an indium oxide molybdenum praseodymium target material precursor; the precursor is loaded into a mold for vacuum forming to obtain an indium oxide molybdenum praseodymium element embryo; the indium oxide molybdenum praseodymium element embryo is sintered to obtain a high-density indium oxide molybdenum praseodymium target material, and the prepared indium oxide molybdenum praseodymium has a higher forming rate and better density.

[0006] However, there has been a lack of research on whether a controllable microsphere gelation process can be achieved for minor actinides, especially trivalent metal ions, to prepare target particles with high sphericity, making it difficult to prepare trivalent metal oxide microspheres in a controllable manner. Summary of the Invention

[0007] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a method for preparing target particles for metal oxide irradiation, provide a solution for microsphere target materials suitable for trivalent ions, realize the controllable gel preparation of metal ions with multiple valence states, and form oxide microspheres with high sphericity through sintering.

[0008] The purpose of the present invention can be achieved by the following technical solutions:

[0009] By using ammonium citrate, glycine and urotropine solution as a complexing liquid and adjusting the acidity, gel balls containing one or more elements of Gd, Ce, Pu, Th, Eu, Am and Cm can be prepared. The obtained gel balls can be dehydrated and calcined to obtain metal oxide target particles with high sphericity.

[0010] The present invention provides a method for preparing target particles for metal oxide irradiation, comprising the following steps:

[0011] S1: Preparing a precursor solution: Prepare a complex solution of ammonium citrate, glycine, and hexamethylenetetramine in a ratio of 0.9-1.2:1:1. Slowly drip the metal nitrate solution into the complex solution to form a suspension. Then drip nitric acid into the suspension. Observe the change in pH value and adjust the pH to 3.5-2.7 until the liquid becomes clear to form a precursor solution.

[0012] S2: Hot silicone oil curing: The precursor liquid is dripped into the hot silicone oil through a capillary tube, and gel microspheres are formed after curing;

[0013] S3: n-octanol dehydration: the gel microspheres are collected and immersed in n-octanol for dehydration to further remove the water in the gel microspheres;

[0014] S4: Calcination: Calcination of the dehydrated gel microspheres to obtain target particles.

[0015] Furthermore, in S2, the inner diameter of the capillary is 90-150 μm.

[0016] Furthermore, in S2, the temperature of the hot silicone oil is 95°C.

[0017] Furthermore, in S4, the calcination temperature ranges from 600 to 900°C.

[0018] Furthermore, in S4, the calcination heating rate is 1-5°C / min.

[0019] Furthermore, in S4, the calcination time is 2-6 hours.

[0020] Furthermore, in S4, the dehydrated gel microspheres are placed in a crucible of a muffle furnace for calcination.

[0021] In S1, the metal ions in the metal nitrate include one or a combination of any of Gd, Ce, Pu, Th, Eu, Am, and Cm, such as a gadolinium nitrate pentahydrate solution, a cerium nitrate hexahydrate solution, and a europium nitrate hexahydrate solution.

[0022] The amount of ammonium citrate and the pH value of the precursor solution are key to the method. The role of ammonium citrate is to form a citrate complex with the metal ions, reducing the degree of hydrolysis of the metal ions. When the molar ratio of ammonium citrate to urotropine is less than 0.9, the addition of a metal nitrate solution makes the resulting suspension very viscous, which is not conducive to the formation of droplets. The addition of nitric acid is to eliminate precipitation in the suspension. If the amount is too small, the solution cannot be kept clear and the capillary is blocked. If excessive addition is made, the pH value of the precursor solution is less than 2.7, and curing cannot be completed in hot silicone oil.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] The present invention provides a solution for microsphere targets suitable for trivalent ions, enabling the controlled preparation of gels of metal ions in various valence states. Sintering forms oxide microspheres with high sphericity. A complex solution containing ammonium citrate, glycine, and hexamethylenetetramine in a ratio of 0.9-1.2:1:1 is used. After adding a metal nitrate solution, the pH of the solution is adjusted to an appropriate level to allow solidification into intact gel spheres in hot silicone oil. Subsequent dehydration and calcination produce metal oxide target particles with high sphericity. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The present invention is a process flow chart of a method for preparing target particles for metal oxide irradiation.

[0026] Figure 2 This is a microscopic image of the precursor droplets prepared in Example 1.

[0027] Figure 3 This is a microscopic image of the precursor solution during the gelation process in Example 2.

[0028] Figure 4 This is a microscopic image of the metal oxide microspheres formed after calcining the gel spheres in Example 3. DETAILED DESCRIPTION

[0029] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. Any features such as component models, preparation methods, materials, structures, or composition ratios not explicitly described in this technical solution are considered to be common technical features disclosed in the prior art.

[0030] Example 1

[0031] This embodiment provides a method for preparing target particles for metal oxide irradiation, such as Figure 1 As shown, the following steps are included:

[0032] S1: Prepare precursor solution: prepare 20 mL of mixed complex solution containing ammonium citrate, glycine, and hexamethylenetetramine at concentrations of 1.2M, 1M, and 1M, slowly drip 20 mL of 1.6M gadolinium nitrate pentahydrate solution into the prepared mixed complex solution to form a suspension, then drip 3M nitric acid into the suspension, observe the change in pH value, and adjust the pH to 3.2 to form a transparent and clear precursor solution, such as Figure 2 Shown is a microscopic image of the prepared precursor solution;

[0033] S2: Hot silicone oil curing: The precursor solution is dripped into 95°C silicone oil through a capillary with an inner diameter of 90 μm. After curing for 15 minutes, gadolinium gel microspheres with high strength are formed;

[0034] S3: n-octanol dehydration: the gel microspheres are collected and immersed in n-octanol for dehydration to further remove the water in the gel microspheres;

[0035] S4: Calcination: The dehydrated gel microspheres are placed in a crucible of a muffle furnace, heated to 900° C. at a heating rate of 1° C. / min, and calcined for 6 h to obtain gadolinium trioxide spherical particles.

[0036] Example 2

[0037] The present invention provides a method for preparing target particles for metal oxide irradiation, comprising the following steps:

[0038] S1: Prepare a precursor solution: prepare 20 mL of a mixed complex solution containing ammonium citrate, glycine, and hexamethylenetetramine at concentrations of 1 M, 1 M, and 1 M, slowly dropwise add 20 mL of a 1.4 M cerium nitrate hexahydrate solution into the prepared mixed complex solution to form a suspension, then dropwise add 3 M nitric acid into the suspension, observe the change in pH, and adjust the pH to 2.7 to form a transparent and clear precursor solution;

[0039] S2: Hot silicone oil curing: The precursor liquid is dropped into 95℃ silicone oil through a capillary with an inner diameter of 90μm. After curing for 2 minutes, cerium gel microspheres with high strength are formed, such as Figure 3 Shown is a microscopic image of the precursor solution during the gelation process;

[0040] S3: n-octanol dehydration: the gel microspheres are collected and immersed in n-octanol for dehydration to further remove the water in the gel microspheres;

[0041] S4: Calcination: The dehydrated gel microspheres were placed in a crucible of a muffle furnace, heated to 700° C. at a heating rate of 1° C. / min, and calcined for 6 h to obtain cerium dioxide spherical particles.

[0042] Example 3

[0043] The present invention provides a method for preparing target particles for metal oxide irradiation, comprising the following steps:

[0044] S1: Prepare a precursor solution: prepare 20 mL of a mixed complex solution containing ammonium citrate, glycine, and hexamethylenetetramine at concentrations of 0.9 M, 1 M, and 1 M, slowly drop 20 mL of a 1.6 M europium nitrate hexahydrate solution into the prepared mixed complex solution to form a suspension, then drop 3 M nitric acid into the suspension, observe the change in pH, and adjust the pH to 3.5 to form a transparent and clear precursor solution;

[0045] S2: Hot silicone oil curing: The precursor solution is dripped into 95°C silicone oil through a capillary with an inner diameter of 90 μm. After curing for 30 minutes, europium gel microspheres with high strength are formed;

[0046] S3: n-octanol dehydration: the gel microspheres are collected and immersed in n-octanol for dehydration to further remove the water in the gel microspheres;

[0047] S4: Calcination: Place the dehydrated gel microspheres into a crucible in a muffle furnace, heat the temperature to 700°C at a heating rate of 1°C / min, and calcine for 2h to obtain europium trioxide spherical particles, such as Figure 4 The figure shows a microscopic image of metal oxide microspheres formed after calcination of gel microspheres, which have high sphericity.

[0048] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A method for preparing target particles for metal oxide irradiation, characterized in that: The following steps are involved: S1: Preparing a precursor solution: preparing a complex solution of ammonium citrate, glycine, and urotropine in a molar ratio of 0.9-1.2:1:1, slowly dripping a metal nitrate solution into the complex solution to form a suspension, then dripping nitric acid into the suspension, observing the change in pH, and adjusting the pH to 3.5-2.7 until the liquid becomes clear to form a precursor solution; S2: Hot silicone oil curing: The precursor liquid is dripped into the hot silicone oil through a capillary tube, and gel microspheres are formed after curing; S3: n-octanol dehydration: collecting the gel microspheres and immersing them in n-octanol for dehydration to further remove water from the gel microspheres; S4: Calcination: Calcination of the dehydrated gel microspheres to obtain target particles.

2. The method for preparing target particles for metal oxide irradiation according to claim 1, characterized in that: In S2, the inner diameter of the capillary is 90-150 μm.

3. The method for preparing target particles for metal oxide irradiation according to claim 1, characterized in that: In S2, the temperature of the hot silicone oil is 95°C.

4. The method for preparing target particles for metal oxide irradiation according to claim 1, characterized in that: In S4, the calcination temperature ranges from 600 to 900°C.

5. The method for preparing target particles for metal oxide irradiation according to claim 1, characterized in that: In S4, the calcination heating rate is 1-5°C / min.

6. The method for preparing target particles for metal oxide irradiation according to claim 1, characterized in that: In S4, the calcination time is 2-6 hours.

7. The method for preparing target particles for metal oxide irradiation according to claim 1, characterized in that: In S4, the dehydrated gel microspheres are placed in a crucible of a muffle furnace for calcination.

8. The method for preparing target particles for metal oxide irradiation according to claim 1, characterized in that: In S1, the metal nitrate solution is a gadolinium nitrate pentahydrate solution.

9. The method for preparing target particles for metal oxide irradiation according to claim 1, characterized in that: In S1, the metal nitrate solution is a cerium nitrate hexahydrate solution.

10. The method for preparing target particles for metal oxide irradiation according to claim 1, characterized in that: In S1, the metal nitrate solution is a europium nitrate hexahydrate solution.

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