Technology for recovery of uranium in ceramic UO2 pellet by supercritical CO2 extraction

A supercritical and extraction technology, which is applied in the field of uranium in ceramic UO2 pellets extracted by supercritical CO2, can solve the problems of small ion exchange treatment capacity, large critical safety hazards, and low degree of automation, so as to reduce critical safety hazards, High extraction efficiency and selectivity, high degree of automation

Inactive Publication Date: 2013-02-20
NUCLEAR POWER INSTITUTE OF CHINA
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  • Summary
  • Abstract
  • Description
  • Claims
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AI Technical Summary

Problems solved by technology

[0002] For Ceramic UO 2 The recovery process of uranium in pellets has been reported in the literature: after dissolving it with different acids, select different extraction agents for liquid-liquid extraction to separate and recover uranium; this method has the following defects: the amount of waste liquid Large size, low degree of automation, complicated operation steps, and large critical safety hazards
The main disadvantages of ion exchange are small processing capacity, long cycle and complicated operation
[0003] Supercritical CO 2 Based on its own characteristics of high efficiency, environmental protection and safety, the extraction process has been studied and applied in biomedicine, but there is still no precedent for the application of the extraction system composed of it and entrainer in the field of nuclear fuel recovery

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] 1. Sc-CO 2 / TBP-HNO 3 Preparation: use 60% ~ 70% HNO 3 Mix-clarify operation with TBP, adjust HNO by adding TBP 3 / TBP ratios are 0.6, 0.8, 1.0, 1.3, 1.4, and finally used as the extraction agent used in the process, and then it is placed in a closed container, and CO 2 , adjust the temperature at 50°C to 60°C; the pressure at 10MPa, stabilize the system until a uniform Sc-CO 2 / TBP-HNO 3 supercritical phase.

[0024] 2. Extraction sample preparation: the ceramic UO 2 The pellets are placed in a calciner, fed with air or oxygen, and calcined at 850°C to 900°C for 4h to 5h.

[0025] 3. Extraction and separation of the first group: different HNO as described in step 1 3 / TBP ratio, the extraction was carried out under the conditions of temperature 60°C, pressure 15MPa, extraction time 2h, extraction agent 30mL, and extraction sample 7g. After the extraction is completed, the loaded supercritical phase is transferred to the separator for separation.

[0026] 4. Se...

Embodiment 2

[0029] 1. Carry out Sc-CO according to the requirements of 1 and 2 in Example 1 2 / TBP-HNO 3 Preparation and Extraction Sample Preparation.

[0030] 2. Extractant usage control: control Sc-CO 2 / TBP-HNO 3 Medium TBP-HNO 3 The organic phases were 20mL, 25mL, 27mL, 30mL, 40mL, respectively.

[0031] 3. Extraction and separation of the second group: In step 2, the amount of different extractants used, respectively at a temperature of 60°C, a pressure of 15MPa, an extraction time of 2h, and HNO 3 / TBP ratio of 1.4, the extraction sample was extracted under the conditions of 7g. After the extraction is completed, the loaded supercritical phase is transferred to the separator for separation.

[0032] 4. Separation of the extraction product is carried out according to the requirements of step 4 in Example 1. After complete separation, the product was collected.

[0033] As the amount of extractant used increases, the extraction efficiency of uranium increases linearly until t...

Embodiment 3

[0035] 1. Carry out Sc-CO according to the requirements of 1 and 2 in Example 1 2 / TBP-HNO 3 Preparation and Extraction Sample Preparation.

[0036] 2. Extraction and separation of the third group: at a temperature of 60°C, a pressure of 15MPa, an extractant of 30mL, HNO 3 Under the conditions of / TBP ratio 1.4 and extraction sample 7g, the six groups of samples were extracted for 15min, 30min, 45min, 60min, 90min, 120min respectively. After the extraction is completed, the loaded supercritical phase is transferred to the separator for separation.

[0037] 3. Separation of the extraction product is carried out according to the requirements of step 4 in Example 1. After complete separation, the product was collected for analysis.

[0038] With the increase of extraction time, the extraction efficiency of uranium increased slowly at first, then accelerated after 30 minutes, and the complete extraction of uranium could be basically realized after 45 minutes.

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PUM

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Abstract

The invention belongs to a technology for recovery of uranium in a ceramic UO2 pellet by supercritical CO2 extraction. The technology includes the steps of: (1) preparing Sc-CO2/TBP-HNO3; (2) preparing a UO2 extraction sample; (3) extracting the extraction raw material in step (2) by an extraction system of Sc-CO2/TBP-HNO3; and (4) separating an extracted product. The technology provided in the invention has the advantages of minimum secondary radioactive waste, high automation degree, high extraction efficiency and selectivity, high extraction capacity, fast extraction speed, maximum reduction of nuclear material retention time, critical safety risk reduction, and minimum damage to the environment and operators.

Description

technical field [0001] The invention belongs to a spent fuel reprocessing process or a recovery process for chemical substandard products in the nuclear fuel production process, and specifically relates to a process using supercritical CO 2 Extraction and recovery of ceramic UO 2 Process for uranium in pellets. Background technique [0002] For Ceramic UO 2 The recovery process of uranium in pellets has been reported in the literature: after dissolving it with different acids, select different extraction agents for liquid-liquid extraction to separate and recover uranium; this method has the following defects: the amount of waste liquid Large size, low degree of automation, complex operation steps, and critical safety hazards. The main disadvantages of ion exchange are small processing capacity, long cycle and complicated operation. [0003] Supercritical CO 2 Based on its own characteristics of high efficiency, environmental protection and safety, the extraction proces...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22B3/04C22B60/02
Inventor 李佳朱常桂刘锦洪刘小龙任萌
Owner NUCLEAR POWER INSTITUTE OF CHINA
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