Method for recovering irradiated niobium-gallium packaged target material

Abstract

The invention relates to the technical field of 68Ge preparation, in particular to a method for recycling a niobium-gallium packaged target after irradiation. According to the method, the irradiated target material is firstly heated to melt the metal gallium in the target material, so that the target material has flowability, and then the packaging target is flushed by adopting the acid / alkali and hydrogen peroxide mixed solution, so that a solution in which the irradiated target material is dissolved cannot be adhered to a pipeline and the wall of a dissolver, and the loss of the metal gallium is avoided; and meanwhile, the 68Ge in the target material is efficiently recovered, and the recovery rate of the 68Ge is increased.

Description

Technical Field

[0001] The present invention relates to 68 The technical field of Ge preparation, and more particularly to a method for recovering target material after irradiation of a niobium-gallium packaged target. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] 68 The initial application of Ge was as a long-lived positron source for attenuation correction and calibration of PET scanners, however, with the introduction of positron emission tomography / computed tomography (PET / CT), attenuation correction is now done with X-rays rather than radioactive sources. 68 The main application of Ge is to use 68 Ge as the parent nuclide 68 Ge / 68 Ga generator.

[0004] at present 68 There are three main ways to prepare Ge nuclides. One of them is to encapsulate natural gallium (Ga-69 and Ga-71) in an encapsulated target composed of niobium or niobium-zirconium alloy, and then use a high-power proton beam line to pass through the encapsulated target film and bombard the target material. The protons irradiate the encapsulated target to produce 68 Ge, the advantage of this method is that it produces very few impurities, which is convenient for subsequent 68 The separation and purification of Ge solution reduces the cost of the separation and purification process. However, the temperature of the gallium metal target will rise above the melting point of gallium (29.76°C) during the irradiation process, and the gallium metal exists in the form of a liquid gallium metal film in the Nb cladding. The gallium metal target after irradiation cooling faces the problem of how to cleanly remove the gallium metal film from the Nb cladding, because liquid gallium metal is very easy to adhere to the surface of materials including but not limited to metal, plastic, glass, etc. In addition, during the transfer of gallium metal from the Nb cladding to the target dissolver, gallium metal may adhere to the pipe and the dissolver wall. The above two situations will lead to gallium metal adhesion loss, which may ultimately affect 68 Ge recovery rate. Summary of the invention

[0005] In order to overcome the above problems, the present invention provides a method for recovering irradiated niobium-gallium packaged target target.

[0006] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0007] A method for recovering irradiated niobium-gallium packaged target material comprises the following steps:

[0008] (1) heating the niobium-gallium packaged target after irradiation cooling to melt the metal gallium in the target material in the packaged target;

[0009] (2) Turn on the heated packaged target;

[0010] (3) Use a mixture of hydrogen peroxide and acid or alkali to rinse the target material and package the target.

[0011] In one or more embodiments, in step (1), the niobium gallium encapsulated target is heated after irradiation cooling by water bath heating.

[0012] In one or more embodiments, in step (1), the heating temperature is 40-50° C. and the heating time is 5-10 min.

[0013] In one or more embodiments, in step (3), a mixed solution of acid and hydrogen peroxide is used to rinse the packaged target.

[0014] Preferably, the acid comprises one or more of hydrochloric acid and sulfuric acid.

[0015] Preferably, the concentration of the acid is 2 to 5 mol / L, preferably 4 mol / L.

[0016] In one or more embodiments, in step (3), the concentration of hydrogen peroxide is 25-30%, preferably 30%.

[0017] Preferably, the volume ratio of the acid to hydrogen peroxide is 7 to 10:1, preferably 8:1.

[0018] In one or more embodiments, in step (3), a mixed solution of alkali and hydrogen peroxide is used to rinse the packaged target.

[0019] Preferably, in the mixture of alkali and hydrogen peroxide, the alkali comprises sodium hydroxide solution or potassium hydroxide solution.

[0020] Preferably, in the mixed solution of alkali and hydrogen peroxide, the concentration of the alkali is 2 to 5 mol / L, preferably 4 mol / L.

[0021] Further preferably, the volume ratio of the alkali to hydrogen peroxide is 7 to 10:1, preferably 8:1.

[0022] The beneficial effects of the present invention are:

[0023] In the present invention, the irradiated target material is first heated to melt the metal gallium in the target material to make the target material fluid, and then the packaged target is washed with a mixed solution of hydrogen peroxide and acid or alkali, which not only prevents the solution that dissolves the irradiated target material from adhering to the pipe and the wall of the dissolver to avoid the loss of metal gallium, but also68 Ge can be recycled efficiently to improve 68 Ge recovery rate. Specifically, the irradiated target includes 68 Various nuclides including Ge and unreacted 69 Ga, the various radionuclides produced by irradiation will react with the unreacted 69 Ga mixed, and multiple nuclides will also react with the cladding Nb and unreacted 69 Ga forms a multiphase alloy. In order to improve the irradiation 68 The recovery rate of Ge requires the two parts to contain 68 The Ge target material is recovered. The acid or alkali in the recovery solution of the present invention can destroy 69 The oxide film formed by Ga 69 Ga will aggregate into a sphere due to surface tension. At the same time, due to the destruction of the oxide film, the hydrogen bond formed between gallium oxide and the hydroxyl group in the solution is destroyed. Gallium oxide is no longer adsorbed by the hydrogen bond of the solution, reducing the wettability of metal gallium. Therefore, the solution that dissolves the irradiated target will not adhere to the pipe and the dissolver wall, thereby improving 68 Ge recovery rate; Furthermore, the added hydrogen peroxide can dissolve the 68 Ge, specifically, 68 Ge will be oxidized in situ by hydrogen peroxide to form germanium oxide, which will react with hydrochloric acid to form soluble germanium salt, which can then be directly transferred to the next step of germanium recovery equipment. 68 Ge targets are recycled, which can greatly improve 68 Ge recovery rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0025] Figure 1 The effect diagram of the packaged target before and after flushing, a is before flushing, b is after flushing;

[0026] Figure 2 The effect of the dissolver after flushing in Examples 1 to 4 and Comparative Examples 3 to 7;

[0027] Figure 3 This is a verification experiment effect diagram of the reaction process of germanium powder with hydrochloric acid and hydrogen peroxide. DETAILED DESCRIPTION

[0028] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0029] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0030] Table 1 shows the source term results of natural gallium-69 encapsulated in a niobium encapsulated target, irradiated for 20 days at a 50MeV 100μA accelerator, and cooled for 18 days. The main elements produced by irradiation are Ge, Zn, Co, Ni, etc. Among them, 68 Most of Ge is uniformly dissolved in metallic gallium. In addition, Ge is also generated at the Ga / Nb metal interface. 68 Ge, so it is necessary to recycle these two parts of the target to improve 68 Recovery rate of Ge.

[0031] Table 1 Source term results of 50MeV 100μA accelerator irradiation for 20 days and cooling for 18 days

[0032] Mass number Number of protons Nuclide Activity / Bq Activity / mCi Uncertainty Mass / μg 60 27 Co-60 <![CDATA[6.12×10 5 ]]> 0.0165 9.89 0.0146 63 28 Ni-63 <![CDATA[2.65×10 6 ]]> 0.0717 0.91 1.2766 65 30 Zn-65 <![CDATA[1.47×10 10 ]]> 396.5135 0.16 48.1064 67 31 Ga-67 <![CDATA[4.87×10 10 ]]> 1316.6486 0.06 2.2017 71 32 Ge-71 <![CDATA[1.06×10 11 ]]> 2871.2973 0.12 17.8312 68 32 Ge-68 <![CDATA[1.08×10 11 ]]> 2929.0270 0.06 412.9163

[0033] The packaged target was irradiated at 50 MeV 100 μA accelerator for 20 days and then cooled for 18 days. Figure 1 As shown in a, the gallium film inside the packaged target can be seen.

[0034] The target material is heated to 45°C to melt the metal gallium in the target material, and the molten target material is transferred to a dissolver. After cooling, the target material is transferred to a dissolver. Figure 2 As described in ③, the target material adheres to the bottom and surrounding of the dissolver.

[0035] Example 1

[0036] (1) heating the irradiated packaged target to 43° C. in a water bath to melt the metal gallium in the target;

[0037] (2) piercing the heated encapsulated target; transferring the heated target material to a dissolver;

[0038] (3) A mixture of 4 mol / L hydrochloric acid and 30% by mass hydrogen peroxide solution (the volume ratio of hydrochloric acid to hydrogen peroxide is 8:1) is used to rinse the target material, the packaged target, and the dissolver.

[0039] The photo of the packaged target after washing is shown in Figure 1 As shown in b, compared Figure 1 It can be seen from the pictures before and after flushing that the flushing agent provided by the present invention has a good flushing effect.

[0040] The effect of the flushed dissolver is as follows Figure 2 As shown in ①.

[0041] Example 2

[0042] (1) heating the irradiated packaged target to 45° C. in a water bath to melt the metal gallium in the target;

[0043] (2) piercing the heated encapsulated target; transferring the heated target material to a dissolver;

[0044] (3) A mixture of 3.5 mol / L hydrochloric acid and 30% by mass hydrogen peroxide solution (the volume ratio of hydrochloric acid to hydrogen peroxide is 8:1) is used to rinse the target material, the packaged target, and the dissolver.

[0045] The effect of the flushed dissolver is as follows Figure 2 As shown in ⑦.

[0046] Example 3

[0047] (1) heating the irradiated packaged target to 46° C. in a water bath to melt the metal gallium in the target;

[0048] (2) piercing the heated encapsulated target; transferring the heated target material to a dissolver;

[0049] (3) A mixture of 4 mol / L sodium hydroxide solution and 30% by mass hydrogen peroxide solution (the volume ratio of the sodium hydroxide solution to hydrogen peroxide is 8:1) is used to rinse the target material, the packaged target, and the dissolver.

[0050] The effect of the flushed dissolver is as follows Figure 2 As shown in ②.

[0051] Example 4

[0052] (1) heating the irradiated packaged target to 48° C. in a water bath to melt the metal gallium in the target;

[0053] (2) piercing the heated encapsulated target; transferring the heated target material to a dissolver;

[0054] (3) A mixture of 4 mol / L potassium hydroxide solution and 30% by mass hydrogen peroxide solution (the volume ratio of potassium hydroxide solution to hydrogen peroxide is 8:1) is used to rinse the target material, packaged target and dissolver.

[0055] The effect of the flushed dissolver is as follows Figure 2 As shown in ⑧.

[0056] Comparative Example 1

[0057] (1) heating the irradiated packaged target to 45° C. in a water bath to melt the metal gallium in the target;

[0058] (2) piercing the heated encapsulated target; transferring the heated target material to a dissolver;

[0059] (3) Use 4 mol / L hydrochloric acid to rinse the target, packaged target and dissolver.

[0060] Comparative Example 2

[0061] (1) heating the irradiated packaged target to 45° C. in a water bath to melt the metal gallium in the target;

[0062] (2) piercing the heated encapsulated target; transferring the heated target material to a dissolver;

[0063] (3) Use 4 mol / L sodium hydroxide solution to rinse the target material, packaged target and dissolver.

[0064] Comparative Example 3

[0065] (1) heating the irradiated packaged target to 45° C. in a water bath to melt the metal gallium in the target;

[0066] (2) piercing the heated encapsulated target; transferring the heated target material to a dissolver;

[0067] (3) The target material, packaged target and dissolver are rinsed with a hydrogen peroxide solution with a mass fraction of 30%.

[0068] The effect of the dissolver after flushing is similar to the following Figure 2 The effects of ③ are the same, basically there is no difference.

[0069] Comparative Example 4

[0070] (1) heating the irradiated packaged target to 45° C. in a water bath to melt the metal gallium in the target;

[0071] (2) piercing the heated encapsulated target; transferring the heated target material to a dissolver;

[0072] (3) A mixture of 0.1 mol / L hydrochloric acid and 30% by mass hydrogen peroxide solution (the volume ratio of hydrochloric acid to hydrogen peroxide is 8:1) is used to rinse the target material, the packaged target, and the dissolver.

[0073] The effect of the flushed dissolver is as follows Figure 2 As shown in ④.

[0074] Comparative Example 5

[0075] (1) heating the irradiated packaged target to 45° C. in a water bath to melt the metal gallium in the target;

[0076] (2) piercing the heated encapsulated target; transferring the heated target material to a dissolver;

[0077] (3) A mixture of 0.1 mol / L sodium hydroxide solution and 30% by mass hydrogen peroxide solution (the volume ratio of sodium hydroxide solution to hydrogen peroxide is 8:1) is used to rinse the target material, packaged target and dissolver.

[0078] The effect of the flushed dissolver is as follows Figure 2 As shown in ⑤.

[0079] Comparative Example 6

[0080] (1) heating the irradiated packaged target to 45° C. in a water bath to melt the metal gallium in the target;

[0081] (2) piercing the heated encapsulated target; transferring the heated target material to a dissolver;

[0082] (3) A mixture of 0.05 mol / L sodium hydroxide solution and 30% by mass hydrogen peroxide solution (the volume ratio of sodium hydroxide solution to hydrogen peroxide is 8:1) is used to rinse the target material, packaged target and dissolver.

[0083] The effect of the flushed dissolver is as follows Figure 2 As shown in Figure 9.

[0084] Comparative Example 7

[0085] (1) heating the irradiated packaged target to 40° C. in a water bath to melt the metal gallium in the target;

[0086] (2) piercing the heated encapsulated target; transferring the heated target material to a dissolver;

[0087] (3) A mixture of 1 mol / L sodium citrate and 30% by mass hydrogen peroxide solution (the volume ratio of sodium hydroxide solution to hydrogen peroxide is 8:1) is used to rinse the target material, packaged target, and dissolver.

[0088] The effect of the flushed dissolver is as follows Figure 2 As shown in ⑥ and ⑩.

[0089] From the effects of the dissolvers after flushing in Examples 1 to 4 and Comparative Examples 3 to 7, it can be seen that high-concentration acid or alkaline solutions can quickly destroy the oxide film on the surface of the metal gallium, and the metal gallium that has destroyed the oxide film will quickly agglomerate due to its own properties. Low-concentration acid or alkaline solutions will also destroy the metal gallium oxide film, eventually forming many small metal gallium particles, but it is difficult to continue to agglomerate. When flushing with hydrogen peroxide solution, the gallium does not agglomerate because the metal gallium film cannot be removed.

[0090] The recovery rates of germanium in Examples 1 to 2 and Comparative Examples 1 to 7 are shown in Table 2.

[0091] Table 2 Recovery rate of germanium in Examples 1 to 2 and Comparative Examples 1 to 7

[0092]

[0093]

[0094] As can be seen from Table 2, adding hydrogen peroxide to the flushing agent can significantly improve 68 The recovery rate of Ge. This is because the contact surface between the metal gallium and the Nb shell will be irradiated to generate a small amount of germanium. This part of germanium exists at the interface between the metal gallium and the Nb shell, and it is difficult to be washed into the dissolver with the metal gallium. After adding hydrogen peroxide, the germanium at the interface is in situ oxidized to generate germanium oxide, which is finally dissolved by the acid and alkali solution and flows into the dissolver with the metal gallium. The reaction equation of germanium powder with hydrochloric acid and hydrogen peroxide is:

[0095] Ge+2H 2 O 2 →GeO 2 +2H 2 O

[0096] GeO 2 +4HCl→GeCl 4 +2H 2 O

[0097] Verification of the reaction process of germanium powder with hydrochloric acid and hydrogen peroxide:

[0098] Hydrogen peroxide with a mass fraction of 5%, 10%, and 30% was used to react with a small amount of germanium powder, respectively, at a reaction temperature of 40-50°C and a solvent volume of 10 mL. During the reaction, it was found that the higher the concentration of hydrogen peroxide, the faster the reaction. After the reaction, the solution was white and turbid, and sediment was observed at the bottom of the centrifuge tube. Figure 3 As shown in the figure below, serial numbers ② to ④ are the states of the solutions after the reaction of hydrogen peroxide solutions with different concentrations and germanium powder. It can be clearly seen that sediment appears at the bottom of the centrifuge tube. Subsequently, 4M hydrochloric acid is added to the solutions ② to ④ after the reaction, and the sediment does not dissolve. The sediment is germanium dioxide generated by the reaction of germanium powder and hydrogen peroxide. Figure 3 The state of the solution after the reaction of 4M hydrochloric acid + 30% hydrogen peroxide mixed solution with metallic germanium powder is shown in the sequence number ①. The difference from sequence numbers ② to ④ is that the solution is clear after the reaction, and no sediment appears at the bottom. The experimental phenomenon shows that the hydrogen peroxide solution reacts with the germanium powder to generate insoluble germanium dioxide. The germanium dioxide in this state is as difficult to react and dissolve with hydrochloric acid as the germanium dioxide purchased on the market. However, when hydrochloric acid and hydrogen peroxide are mixed and added to the germanium powder for reaction, the germanium oxide generated in situ immediately reacts with the hydrochloric acid, and finally the black germanium powder is completely dissolved, and the solution is clear.

[0099] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for recovering irradiated niobium-gallium packaged target material, characterized in that: The following steps are involved: (1) heating the niobium-gallium packaged target after irradiation cooling to melt the metal gallium in the target material in the packaged target; (2) Turn on the heated packaged target; (3) Use a mixture of hydrogen peroxide and acid or alkali to rinse the target material and package the target.

2. The method according to claim 1, characterized in that In step (1), the niobium gallium encapsulation target after irradiation cooling is heated by water bath heating; Or, the heating temperature is 40-50°C; the heating time is 5-10 minutes.

3. The method according to claim 1, characterized in that In step (1) and step (3), a mixed solution of acid and hydrogen peroxide is used to rinse the packaged target.

4. The method according to claim 3, characterized in that The acid includes one or more of hydrochloric acid and sulfuric acid; Alternatively, the concentration of the acid is 2 to 5 mol / L, preferably 4 mol / L.

5. The method according to claim 1, characterized in that The concentration of hydrogen peroxide is 25-30%, preferably 30%.

6. The method according to claim 5, characterized in that The volume ratio of the acid to hydrogen peroxide is 7 to 10:1, preferably 8:

1.

7. The method according to claim 1, characterized in that In step (3), the packaged target is rinsed with a mixture of alkali and hydrogen peroxide.

8. The method according to claim 7, characterized in that The base includes sodium hydroxide solution or potassium hydroxide solution.

9. The method according to claim 8, characterized in that The concentration of the base is 2 to 5 mol / L, preferably 4 mol / L.

10. The method according to claim 9, characterized in that The volume ratio of the alkali to hydrogen peroxide is 7 to 10:1, preferably 8:1.

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