Process for purifying transformed 137Cs from high-level liquid waste

Abstract

The invention belongs to the technical field of radioactive waste liquid purification and transformation, and relates to a process for purifying transformed 137Cs from high-level radioactive waste liquid. The process comprises the following steps: adding AMP / SiO2 ion exchange resin into deionized water for soaking, taking the treated resin as a column filler, and filling the column with the treated resin; a certain amount of 137CsNO3 product liquid is purified through an ion exchange resin column at a certain flow rate, HNO3 is used for pre-balancing and leaching, NH4Cl is used for analysis, and the recovery rate and purity of Cs are improved. According to the purification transformation process of the 137Cs product liquid extracted on the basis of the high-level liquid waste, impurities such as potassium and rubidium with similar chemical properties in the high-level liquid waste can be effectively separated through high-selectivity adsorption of the AMP / SiO2 resin on Cs < + >, the impurity content is reduced from the source, the purity of 137Cs is improved, and finally a high-specific-activity 137CsCl raw material with the radioactive specific activity larger than or equal to 23Ci / g can be prepared.

Description

Technical Field

[0001] This application belongs to the field of radioactive waste purification and transformation technology, and relates to a method for purifying and transforming high-level radioactive waste. 137 Cs process. Background Technology

[0002] In production and scientific research practices, a large amount of high-level radioactive waste liquid is generated. This waste liquid contains nearly 100 isotopes of more than 30 elements, and contains a large amount of... 137 Cs. With the development of post-treatment separation and transmutation technologies, the reuse of high-level radioactive wastewater has a foundation for industrial practice, especially with the increasingly sophisticated TRPO process. 137 This lays a solid foundation for the acquisition of Cs and the generation of economic benefits. Extraction from high-level radioactive waste liquid... 137 While the CsNO3 product solution largely meets the requirements for production and utilization, challenges remain, including difficulties in separating impurities with similar chemical properties, operational limitations under high-radioactivity environments, the availability of degradation reagents (such as extractants and resins), high technical barriers, and high costs. Therefore, the treatment of high-level radioactive waste liquids presents significant challenges. 137 Preparation of high specific activity CsNO3 product liquid purification and conversion 137 Research on CsCl raw materials is not yet mature and cannot be realized. 137 CsNO3 products with high specific activity 137 Effective conversion of CsCl feedstock. Summary of the Invention

[0003] The purpose of this application is to provide a method for purifying and converting high-level radioactive waste liquid using AMP / SiO2 adsorbent as an extraction resin. 137 Preparation of high specific activity CsNO3 product solution 137 Processing technology of CsCl raw materials.

[0004] The technical solution to achieve the purpose of this application is as follows:

[0005] This application provides a method for purifying and transforming high-level radioactive waste liquid. 137 The process of Cs is characterized by comprising the following steps:

[0006] Step 1, Ion exchange column purification: The AMP / SiO2 ion exchange resin is soaked in deionized water. The treated resin is then used as column packing material and loaded into the column. A certain amount of... 137 The CsNO3 product solution was purified by passing it through an ion exchange resin column at a certain flow rate, pre-equilibration and elution were performed using HNO3, and analyzing was performed using NH4Cl to improve the recovery rate and purity of Cs.

[0007] Step 2, Evaporation and Crystallization: Evaporate the water in the eluent at a certain temperature and collect the precipitated solid;

[0008] Step 3, thermal decomposition and transformation: the product collected after evaporation and crystallization... 137 The mixed solid of CsCl and NH4Cl undergoes thermal decomposition at a certain temperature, transforming into a single, stable compound.

[0009] Optionally, the pretreatment soaking time of the AMP / SiO2 ion exchange resin in step one is 24-48 hours.

[0010] Optionally, in step one, the concentration of HNO3 used for pre-equilibration is 1.2 mol / L, and the flow rate is 0.5-1 mL / min; the concentration of HNO3 used for rinsing is 1.2 mol / L, and the flow rate is 0.2-0.5 mL / min.

[0011] Optionally, the purification column flow rate in step one is 0.1 mL / min to 0.3 mL / min.

[0012] Optionally, in step one, the concentration of NH4Cl used for analysis is 3 mol / L, and the flow rate is 0.1-0.3 mL / min.

[0013] Optionally, the evaporation and crystallization temperature in step two is 100℃-110℃.

[0014] Optionally, in step three, the thermal decomposition is converted into a segmented process, with the first segment being 338℃-340℃ and thermal decomposition lasting 2 to 2.5 hours, and the second segment being 380℃ and thermal decomposition lasting 1.5 to 2.5 hours.

[0015] The beneficial technical effects of this application are as follows:

[0016] a. A method based on high-level radioactive waste liquid ( 137 Extracted (Cs specific activity is generally ≥10 Ci / g) 137 The purification and transformation process of Cs product solution involves using AMP / SiO2 resin to purify Cs. + The highly selective adsorption can effectively separate impurities such as potassium and rubidium with similar chemical properties from high-level radioactive waste liquids, reducing the impurity content at the source and improving efficiency. 137 Cs purity;

[0017] b. For the presence of a large amount of NH4Cl in the eluent, the liquid is first converted into a solid mixture through evaporation and crystallization, making subsequent thermal decomposition (NH4Cl easily decomposes into gas upon heating) easier to control.

[0018] Reducing the proportion of high-percentage impurity salts 137 Dilution of CsCl further increases the concentration of CsCl in the product. 137 The relative content of CsCl indirectly increases specific activity;

[0019] c. Ultimately, it is possible to prepare radioactive materials with a specific activity ≥23 Ci / g. 137 CsCl raw material, prepared by this process 137 CsCl feedstock has advantages such as high uniformity and high specific activity. Furthermore,

[0020] Recycling from high-level radioactive waste 137 Cs significantly improves resource utilization, greatly reduces raw material acquisition costs, and is conducive to sustainable development. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to specific embodiments, but it should not be construed as limiting the scope of the above subject matter of the present invention to the following embodiments.

[0022] This invention provides a method for purifying and transforming high-level radioactive waste liquid. 137 The Cs process, the specific steps of which are as follows:

[0023] Step 1: Ion exchange column purification

[0024] The AMP / SiO2 ion exchange resin was soaked in deionized water, and the treated resin was used as column packing material and packed into the column. A certain amount of... 137 The CsNO3 product solution was purified by passing it through an ion exchange resin column at a certain flow rate, followed by pre-equilibration and elution with HNO3, and analyzing with NH4Cl to improve the recovery rate and purity of Cs.

[0025] Due to high specific activity 137 Cs has strong gamma radioactivity, and direct handling would cause serious radiation hazards to personnel. The entire process must be completed in a heated room (a sealed space equipped with heavy shielding) using a remotely controlled robotic arm.

[0026] Step 2, Evaporation and Crystallization

[0027] Because of the eluent 137 When the mass ratio of CsCl to NH4Cl is 1:300, direct heating to the boiling point of NH4Cl (337.8℃) can easily lead to boiling and decomposition. 137 CsCl is lost with the vapor; therefore, the water in the eluent is evaporated at a certain temperature, and the precipitated solid is collected.

[0028] Step 3, thermal decomposition and transformation

[0029] The mixed solid collected after evaporation and crystallization ( 137 CsCl and NH4Cl undergo thermal decomposition at a certain temperature, transforming into a single, stable compound, thus improving the purity of the product.

[0030] Preferably, in step one, the AMP / SiO2 ion exchange resin material pretreatment soaking time is 24-48 h; the HNO3 concentration for ion exchange resin column preequilibration is 1.2 mol / L, and the flow rate is 0.5-1 mL / min; the purification column loading flow rate is 0.1 mL / min-0.3 mL / min; the HNO3 concentration for elution is 1.2 mol / L, and the flow rate is 0.2-0.5 mL / min; the NH4Cl concentration for elution is 3 mol / L, and the flow rate is 0.1-0.3 mL / min.

[0031] Preferably, the evaporation and crystallization temperature in step two is 100℃-110℃.

[0032] Preferably, the thermal decomposition in step three is segmented, with the first segment being 338℃-340℃ for 2-2.5 hours and the second segment being 380℃ for 1.5-2.5 hours.

[0033] The present invention will now be described in detail with reference to the embodiments.

[0034] Example 1

[0035] This embodiment provides a method for purifying and transforming high-level radioactive waste liquid. 137 The preparation process of Cs involves the following steps:

[0036] Step 1: Ion exchange column purification

[0037] The cesium product solution was purified by column chromatography with 1.2 mol / L nitric acid added and pre-equilibrated with the acid solution at a flow rate of 0.5 mL / min. The product was then eluted with 1.2 mol / L nitric acid at a flow rate of 0.1 mL / min. Impurity ions were then eluted with 3 mol / L NH₄Cl solution at a flow rate of 0.1 mL / min to obtain the purified product. 137 Cs liquid feed.

[0038] Step 2, Evaporation and Crystallization

[0039] Purified 137 The Cs solution was evaporated and crystallized at 105°C on a hot plate to obtain a white solid.

[0040] Step 3, thermal decomposition and transformation

[0041] The solid obtained after evaporation was heated at 380℃ for 2 hours to undergo thermal decomposition, yielding... 137 Cs raw materials.

[0042] Example 2

[0043] This embodiment provides a method for purifying and transforming high-level radioactive waste liquid. 137The preparation process of Cs involves the following steps:

[0044] Step 1: Ion exchange column purification

[0045] The cesium product solution was purified by column chromatography using 1.2 mol / L nitric acid at a flow rate of 1 mL / min after pre-equilibration with the acid solution. The column was then loaded with the 1.2 mol / L nitric acid to elute impurity ions at a flow rate of 0.5 mL / min. The eluted column was then elute with 3 mol / L NH₄Cl solution at a flow rate of 0.2 mL / min to obtain the purified product. 137 Cs liquid feed.

[0046] Step 2, Evaporation and Crystallization

[0047] Purified 137 The Cs solution was evaporated and crystallized at 105°C on a hot plate to obtain a white solid.

[0048] Step 3, thermal decomposition and transformation

[0049] The solid obtained after evaporation was heated at 380℃ for 2 hours to undergo thermal decomposition, yielding... 137 Cs raw materials.

[0050] Example 3

[0051] Step 1: Ion exchange column purification

[0052] The cesium product solution was purified by column chromatography with 1.2 mol / L nitric acid added and pre-equilibrated with the acid solution at a flow rate of 0.7 mL / min. The product was then eluted with 1.2 mol / L nitric acid at a flow rate of 0.3 mL / min. The eluted column was then eluted with 3 mol / L NH₄Cl solution at a flow rate of 0.3 mL / min to obtain the purified product. 137 Cs liquid feed.

[0053] Step 2, Evaporation and Crystallization

[0054] Purified 137 The Cs solution was evaporated and crystallized at 105°C on a hot plate to obtain a white solid.

[0055] Step 3, thermal decomposition and transformation

[0056] The solid obtained after evaporation was heated at 380℃ for 2 hours to undergo thermal decomposition, yielding... 137 Cs raw materials.

[0057] In purification and transformation 137 Cs preparation 137The main equipment used in the process of Cs raw material production is shown in the table below.

[0058] Equipment Name quantity Specifications and Models Solid phase extraction instrument 1 YGC-8 electric heating plate 1 EH45C

[0059] In purification and transformation 137 Cs preparation 137 The main materials used in the Cs raw material processing are shown in the table below.

[0060] Material Name Specifications and purity Cs product liquid / <![CDATA[AMP / SiO2]]> / Nitric acid GR cesium chloride GR ammonium chloride GR

[0061] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for purifying and transforming high-level radioactive waste liquid 137 The process of Cs is characterized by, Includes the following steps: Step 1, Ion exchange column purification: The AMP / SiO2 ion exchange resin is soaked in deionized water, and the treated resin is used as column packing material and loaded into the column; a certain amount of... 137 The CsNO3 product solution was purified by passing it through an ion exchange resin column at a certain flow rate, pre-equilibration and elution were performed using HNO3, and analyzing was performed using NH4Cl to improve the recovery rate and purity of Cs. Step 2, Evaporation and Crystallization: Evaporate the water in the eluent at a certain temperature and collect the precipitated solid; Step 3, thermal decomposition and transformation: the product collected after evaporation and crystallization... 137 The mixed solid of CsCl and NH4Cl undergoes thermal decomposition at a certain temperature, transforming into a single, stable compound.

2. The purification and transformation method for high-level radioactive waste liquid according to claim 1 137 The process of Cs is characterized by, The pretreatment soaking time of the AMP / SiO2 ion exchange resin in step one is 24-48 hours.

3. A purification and transformation method for high-level radioactive waste liquid according to claim 2. 137 The process of Cs is characterized by, In step one, the concentration of HNO3 used for pre-equilibration is 1.2 mol / L, and the flow rate is 0.5-1 mL / min; the concentration of HNO3 used for rinsing is 1.2 mol / L, and the flow rate is 0.2-0.5 mL / min.

4. A purification and transformation method for high-level radioactive waste liquid according to claim 3. 137 The process of Cs is characterized by, In step one, the purification column flow rate is 0.1 mL / min - 0.3 mL / min.

5. A purification and transformation method for high-level radioactive waste liquid according to claim 4. 137 The process of Cs is characterized by, In step one, the concentration of NH4Cl used for analysis is 3 mol / L, and the flow rate is 0.1-0.3 mL / min.

6. A method for purifying and transforming high-level radioactive waste liquid according to claim 5. 137 The process of Cs is characterized by, The evaporation and crystallization temperature in step two is 100℃-110℃.

7. A method for purifying and transforming high-level radioactive waste liquid according to claims 1-6 137 The process of Cs is characterized by, In step three, the thermal decomposition is transformed into a segmented process. The first segment is at 338℃-340℃, with thermal decomposition lasting 2 to 2.5 hours. The second segment is at 380℃, with thermal decomposition lasting 1.5 to 2.5 hours.