Method for extracting palladium from high-level liquid waste

A high-level waste liquid extraction technology, applied in the direction of improving process efficiency, can solve the problems of low distribution ratio, long extraction time, poor stability of extraction agent, etc., and achieve the effect of minimizing waste and simplifying process equipment

Active Publication Date: 2012-05-23
CHINA INSTITUTE OF ATOMIC ENERGY
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Problems solved by technology

Most of the reported extraction agents for extracting palladium from high-level radioactive waste have some shortcomings.
Such as tributyl phosphate (TBP) in 0.6-0.7mol / L HNO 3 The distribution ratio of palladium in the extraction of medium is the best, and the maximum extraction distribution ratio is about 1.3; the optimum concentration of nitric acid for the extraction of palladium by trialkylphosphorus oxide (TOPO) is less than 1mol / L, and the maximum extraction distribution ratio of Pd(II) is slightly higher than that of TBP Large; 0.05mol / L dioctyl sulfoxide-Solvesso100 solution system in 3.0mol / L HNO 3 The maximum distribution ratio of extracting Pd(II) in the medium is less than 10; the extraction of Pd(II) nitrate with dialkyl sulfide is very effective, and the distribution ratio of extracting palladium in 1-6mol / L nitric acid solution can reach several hundred, but At the same time, Mo, Zr and other elements are co-extracted, and the extraction time is long, and the distribution equilibrium can only be slowly reached after 8-10 hours; bis(2,4,4-trimethylpentyl)dithiophosphonic acid (Cyanex 301) can Effectively extract Pd(II) from high-level waste liquid, but this extractant has poor stability and is easily oxidized; the distribution ratio of amine extractant to extract palladium in more than 1mol / L nitric acid solution is low, and the selectivity is poor α-benzoin oxime-Solvesso100 is in the scope of 0.1-4mol / L in nitric acid concentration, and the extraction rate to Pd is more than 99.5%, and the decontamination to nuclides such as Ru, U, Pu is all very good, but this method The decontamination of Mo is poor, and the stripping is difficult

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  • Method for extracting palladium from high-level liquid waste

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Embodiment 1

[0031] In this embodiment, a palladium nitric acid solution is used to simulate a high-level waste liquid to carry out a single-stage experiment of extracting palladium. The specific steps are as follows:

[0032] a) prepare palladium solution, wherein C Pd =200 μg / mL, C HNO3 =2mol / L.

[0033] b) prepare TiBPS-xylene solution, wherein C TIBPS = 0.005 mol / L.

[0034] c) The palladium solution and the TiBPS-xylene solution with a ratio of 1:1 were mixed and vortexed, the operating temperature was room temperature, and the extraction time was 15 min.

[0035] d) After the extraction is balanced, the organic phase is separated from the water phase, and the concentration of palladium in the water phase is analyzed to calculate the extraction distribution ratio.

[0036] e) Washing the extract phase to remove impurities.

[0037] f) adding 5% ammonia water to the washed extract phase for back extraction.

[0038] Experimental results: The extraction balance can be reached afte...

Embodiment 2

[0040] In this embodiment, a palladium nitric acid solution is used to simulate a high-level waste liquid to carry out a single-stage experiment of extracting palladium. The specific steps are as follows:

[0041] a) prepare palladium solution, wherein C Pd =200 μg / mL, C HNO3 = 1 mol / L.

[0042] b) prepare TiBPS-xylene solution, wherein C TIBPS = 0.004 mol / L.

[0043] c) The palladium solution and the TiBPS-xylene solution with a ratio of 1:1 were mixed and vortexed, the operating temperature was room temperature, and the extraction time was 15 min.

[0044]d) After the extraction is balanced, the organic phase is separated from the water phase, and the concentration of palladium in the water phase is analyzed to calculate the extraction distribution ratio.

[0045] e) Washing the extract phase to remove impurities.

[0046] f) adding 5% ammonia water to the washed extract phase for back extraction.

[0047] Experimental results: The extraction balance can be reached aft...

Embodiment 3

[0049] In this embodiment, a palladium nitric acid solution is used to simulate a high-level waste liquid to carry out a single-stage experiment of extracting palladium. The specific steps are as follows:

[0050] a) prepare palladium solution, wherein C Pd =200 μg / mL, C HNO3 = 3 mol / L.

[0051] b) prepare TiBPS-xylene solution, wherein C TIBPS = 0.006 mol / L.

[0052] c) The palladium solution and the TiBPS-xylene solution with a ratio of 1:1 were mixed and vortexed, the operating temperature was room temperature, and the extraction time was 15 min.

[0053] d) After the extraction is balanced, the organic phase is separated from the water phase, and the concentration of palladium in the water phase is analyzed to calculate the extraction distribution ratio.

[0054] e) Washing the extract phase to remove impurities.

[0055] f) adding 5% ammonia water to the washed extract phase for back extraction.

[0056] Experimental results: The extraction balance can be reached af...

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Abstract

The invention provides a method for extracting palladium from high-level liquid waste, which belongs to the technical field of radioactive waste after treatment. The high-level liquid waste adopts nitric acid system, and the method comprises the following concrete steps of: a, adequately mixing the high-level liquid waste with extract phase; b, separating extract phase containing palladium from the mixture after extraction equilibrium; c, washing the separated extract phase containing palladium; d, repeating steps b and c 1 to 5 times; e, adding stripping agent to the washed extract phase containing palladium to perform back extraction; and the method is characterized in that triisobutyl phosphine sulfide (TiBPS) is adopted as extracting agent, and thinning agent is added for preparing the extract phase. The method has the following advantages: a, the extracting ratio of palladium in the nitric acid system is high by using TiBPS as extracting agent; b, the concentration range of adaptable nitric acid is wide, Purex process can be directly linked, mixtion is not required in the extraction process, and waste minimization and processing equipment simplification can be realized; c, the selectivity is good; and d, back extraction is easy.

Description

technical field [0001] The invention belongs to the technical field of radioactive waste reprocessing, and in particular relates to a method for extracting palladium from high-level radioactive waste liquid. Background technique [0002] The nuclear fuel in the reactor produces rich metal palladium during the fission process, and its content varies with the type of reactor and the burnup. For example, a pressurized water reactor with a burnup of 33000MWd / t produces about 1.33Kg Pd / tU; A fast breeder reactor with a burnup consumption of 80GWd / t produces about 4.34Kg Pd / tU. After the spent fuel is reprocessed, most of the metal palladium enters the high-level waste liquid. In the vitrification process of high-level waste liquid, the fission product palladium may form interface dirt with some degradation products of tributyl phosphate (TBP), and due to the high melting point of palladium, it will form an independent phase during the vitrification process and deposit on the Th...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22B3/38C22B11/00
CPCY02P10/20
Inventor 李辉波赵兴红王孝荣林灿生常志远苏哲刘占元宋凤丽
Owner CHINA INSTITUTE OF ATOMIC ENERGY
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