Preparation method of strontium-cerium ceramic solidified body with high stability

Abstract

The present invention discloses a method for preparing a highly stable strontium-cesium ceramic solid body, belonging to the technical field of industrial treatment and application of nuclear waste. The present invention uses aluminum silicon molecular sieve as a substrate, mixes aluminum silicon molecular sieve and strontium-cesium waste and presses them, and prepares a strontium-cesium ceramic solid body with good chemical stability through three calcinations and glaze spraying. The present invention solves the problem of Cs volatilization under high temperature conditions; at the same time, a strontium-cesium ceramic solid body with good chemical stability is obtained, which provides a basis for the research and development of separation of high-level radioactive liquid waste. 137 Cs, 90 Sr solidification laid the foundation.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of nuclear waste industrial processing and application technology, in particular to a preparation method of a high-stability strontium-cerium ceramic solidification body. BACKGROUND

[0002] High level waste (HLW) is one of the most difficult forms of nuclear waste to handle, which mainly exists in the form of waste liquid (waste water). Although the volume of high level waste is less than 1% of the volume of nuclear waste generated by nuclear fuel cycle, the radioactivity contained therein exceeds 99% of the total radioactivity of the nuclear fuel cycle. Due to the characteristics of complex composition and large fluctuation of high level waste, the adaptability (multi-nucleus, multi-component), containment (high solid solubility) and stability (mechanical, thermal and irradiation stability) of the solidification matrix are more demanding.

[0003] Cesium garnet is considered to be the best carrier for permanent sealing of radioactive cesium ions due to its inherent spatial pore structure. Since cesium and strontium are both alkali metals, they can be co-solidified. The traditional solidification method of cesium and strontium is to add rocks, alabandite, etc., grind, and press into shape, and then calcine at a high temperature of 1100-1300°C in air; however, cesium is prone to volatilize above 1000°C, resulting in the leakage of nuclides. SUMMARY

[0004] In view of the problems of fixation, volatilization and loss of cesium in the prior art, the present application provides a preparation method of a high-stability strontium-cerium ceramic solidification body, which can be applied to the preparation of a cesium source core, improve the reuse of nuclear waste, and provide a new solidification method for the permanent disposal of strontium-cerium nuclear waste.

[0005] The present application first provides a preparation method of a strontium-cerium ceramic solidification body, comprising the following steps:

[0006] (1) uniformly mixing aluminum-silicon molecular sieve and high-level strontium-cerium waste, pressing into shape, calcining, and obtaining primary cesium garnet;

[0007] (2) crushing and grinding the primary cesium garnet, pressing into shape, calcining, and obtaining secondary cesium garnet;

[0008] (3) spraying glaze on the secondary cesium garnet, and then calcining to obtain the strontium-cerium ceramic solidification body.

[0009] In the above preparation method, the aluminum-silicon molecular sieve is NaY molecular sieve; specifically, the molar ratio of SiO2 / Al2O3 in the NaY molecular sieve can be 4.8-5.6:1;

[0010] The mass percentage of the high-level strontium cesium waste in the total mass of the aluminum-silicon molecular sieve and the high-level strontium cesium waste is 10%-30%.

[0011] The glaze is composed of glaze material and nickel nitrate solution; specifically, the volume ratio of the glaze material and the nickel nitrate solution can be 100:(1-2); the concentration of the nickel nitrate solution can be 0.5-1 g / L.

[0012] In the preparation method, the pressure of the press forming in step (1) is 5-10 MPa.

[0013] The calcination is performed in an air atmosphere.

[0014] The calcination temperature is 700-800℃.

[0015] The calcination time is 1-2 h.

[0016] The calcination temperature is 700-800℃.

[0017] In the preparation method, the pressure of the press forming in step (2) is 8-10 MPa.

[0018] The calcination is performed in an inert atmosphere.

[0019] The calcination temperature is 800-1000℃.

[0020] The calcination time is 1-2 h.

[0021] The calcination temperature is 800-1000℃.

[0022] In the preparation method, the number of times of spraying the glaze in step (3) is 3-5 times.

[0023] The calcination is performed in an air atmosphere.

[0024] The calcination temperature is 700-1000℃.

[0025] The calcination time is 1-2 h.

[0026] The calcination temperature is 700-1000℃.

[0027] In the method, the glaze material is ceramic glaze, specifically, fusible glaze (below 1100℃), medium-temperature glaze (1100-1250℃) or high-temperature glaze (above 1250℃); it is a product purchased on the market and is generally composed of feldspar, kaolin and quartz.

[0028] In the preparation method, the high-level strontium cesium waste is solid.

[0029] In the preparation method, the inert atmosphere is argon or nitrogen atmosphere.

[0030] The application further provides a method for solidifying high-level waste strontium and cesium, comprising the following steps:

[0031] (1) uniformly mixing aluminum-silicon molecular sieve and high-level strontium and cesium waste, pressing into shape, calcining to obtain primary cesium feldspar;

[0032] (2) crushing and grinding the primary cesium feldspar, pressing into shape, and calcining to obtain secondary cesium feldspar;

[0033] (3) spraying glaze on the secondary cesium feldspar, and then calcining to obtain the strontium and cesium ceramic solidification body.

[0034] In the method, the aluminum-silicon molecular sieve is NaY molecular sieve; specifically, the molar ratio of SiO2 / Al2O3 in the NaY molecular sieve can be 4.8-5.6:1.

[0035] The mass percentage of the high-level strontium and cesium waste is 10%-30% based on the total mass of the aluminum-silicon molecular sieve and high-level strontium and cesium waste.

[0036] The glaze is composed of glaze material and nickel nitrate solution; specifically, the volume ratio of the glaze material and nickel nitrate solution can be 100:1-2; and the concentration of the nickel nitrate solution can be 0.5-1 g / L.

[0037] In the method, the glaze is ceramic glaze, specifically, fusible glaze (below 1100℃), medium-temperature glaze (1100-1250℃) or high-temperature glaze (above 1250℃); it is a product purchased on the market, and is generally composed of feldspar, kaolin and quartz.

[0038] In the method, in step (1), the pressure for pressing into shape is 5-10 MPa.

[0039] The calcining is performed in an air atmosphere.

[0040] The calcining temperature is 700-800℃.

[0041] The calcining time is 1-2 h.

[0042] The calcining temperature is 700-800℃.

[0043] In the method, in step (2), the pressure for pressing into shape is 8-10 MPa.

[0044] The calcining is performed in an inert atmosphere.

[0045] The calcining temperature is 800-1000℃.

[0046] The calcination time is 1-2h;

[0047] The calcination temperature is 700-1000℃.

[0048] The preparation method, in step (3), the spraying glaze is 3-5 times;

[0049] The calcination is carried out in air atmosphere;

[0050] The calcination temperature is 700-1000℃.

[0051] The calcination time is 1-2h;

[0052] The calcination temperature is 700-1000℃.

[0053] The preparation method, in step (3), the spraying glaze is 3-5 times;

[0054] The preparation method, in step (3), the spraying glaze is 3-5 times;

[0055] The preparation method, in step (3), the spraying glaze is 3-5 times; 137 Cs, 90 Sr solidification. BRIEF DESCRIPTION OF DRAWINGS

[0056] Figure 1 X-ray diffraction patterns of the strontium cesium ceramic solidification bodies prepared in Examples 1-3. DETAILED DESCRIPTION

[0057] The present application provides a preparation method of a strontium cesium ceramic solidification body or a method for solidification treatment of high-level waste strontium cesium, comprising the following steps:

[0058] (1) uniformly mixing aluminum-silicon molecular sieve and high-level strontium cesium waste, pressing and forming, calcining to obtain primary cesium garnet;

[0059] (2) crushing and grinding the primary cesium garnet, pressing and forming, calcining to obtain secondary cesium garnet;

[0060] (3) spraying glaze on the secondary cesium garnet, then calcining to obtain the strontium cesium ceramic solidification body.

[0061] The method of the present application prepares strontium cesium ceramic solidified body by the method of spraying glaze and three times calcination, solves the problem of Cs volatilization under high temperature condition; at the same time, the strontium cesium ceramic solidified body with good chemical stability is obtained, the normalized leaching rates of strontium and cesium of the solidified body are very low after leaching at 70℃ for 21 days, which lays a foundation for the development of high-level liquid waste separated from 137 Cs, 90 Sr solidification.

[0062] The present application is further described in detail below in conjunction with specific embodiments, and the examples given are only for illustrating the present application, not for limiting the scope of the present application.

[0063] In the following examples, the experimental methods are all conventional methods, unless otherwise specified.

[0064] In the following examples, quantitative tests are all set with three repeated experiments, and the results are averaged.

[0065] In the following examples, the materials and reagents used, unless otherwise specified, can be obtained from commercial channels.

[0066] In the following examples and comparative examples, the aluminum-silicon molecular sieve used is NaY molecular sieve with SiO2 / Al2O3 molar ratio of 5.2:1, which is purchased from Tianjin Nanhua Catalyst Co., Ltd.

[0067] In the following examples and comparative examples, the composition of the simulated strontium cesium high-level liquid waste is shown in Table 1 below.

[0068] Table 1 Composition of simulated strontium cesium high-level liquid waste (anion is NO3 - )

[0069] Element Simulated feed mg / L Ba 2+ ]] 379 Cs + ]] 449 Fe 3+ ]] 0.19 Mo 6+ ]] 27 Na + ]] 11.4 Pd 2+ ]]> 0.606 Rb 2+ ]] 69 Sr 2+ ]]> 142 HNO3 0.3 mol / L

[0070] 5 liters of simulated strontium cesium high-level liquid waste is prepared according to the content in Table 1, and then it is evaporated to dryness, and dried at 100℃ for 6 hours to obtain simulated strontium cesium nitrate.

[0071] In the following examples, the glaze used is water stream transparent glaze medium temperature glaze, which is produced by Jingdezhen Water Stream Star Pottery Art Gallery.

[0072] Example 1

[0073] Take 1.4 g of dry aluminum-silicon molecular sieve and 0.6 g of simulated strontium cesium nitrate, mix them evenly; press the mixture into a φ10 cylindrical core block under 5 MPa; heat the cylindrical core block in air atmosphere at a rate of 5°C / min to 700°C, keep it at this temperature for 1 h, and naturally cool it to room temperature to obtain primary cesium feldspar; crush and grind the primary cesium feldspar, and press it into a shape under 10 MPa; heat it in inert atmosphere (argon) at a rate of 5°C / min to 1000°C, keep it at this temperature for 1 h; and naturally cool it to room temperature to obtain secondary cesium feldspar.

[0074] Take 50 mL of glaze, add 1 g / L of nickel nitrate 0.5 mL, mix evenly, and spray it onto the secondary cesium feldspar, repeat the spraying 5 times; obtain a glaze-sprayed block.

[0075] Heat the glaze-sprayed block in air atmosphere at a rate of 5°C / min to 1000°C, keep it at this temperature for 1 h, and naturally cool it to room temperature to obtain a high-stability strontium cesium ceramic solidified body, the crystal structure of which is shown in Figure 1 .

[0076] The strontium cesium ceramic solidified body prepared in this example is subjected to MCC-1 international leaching method, using deionized water as the leaching agent, and leached at 70°C for 21 days; the normalized leaching rate of strontium is 2.05×10 -4 g.m -2 .d -1 ; the normalized leaching rate of Cs is 5.23×10 - 4 g.m -2 .d -1 .

[0077] Example 2

[0078] Take 1.4 g of dry aluminum-silicon molecular sieve and 0.6 g of simulated strontium cesium nitrate, mix them evenly; press the mixture into a φ10 cylindrical core block under 5 MPa; heat the cylindrical core block in air atmosphere at a rate of 5°C / min to 700°C, keep it at this temperature for 1 h, and naturally cool it to room temperature to obtain primary cesium feldspar; crush and grind the primary cesium feldspar, and press it into a shape under 10 MPa; heat it in inert atmosphere (argon) at a rate of 5°C / min to 1000°C, keep it at this temperature for 1 h; and naturally cool it to room temperature to obtain secondary cesium feldspar.

[0079] Take 50 mL of glaze, add 1 g / L of nickel nitrate 0.5 mL, mix evenly, and spray it onto the secondary cesium feldspar, repeat the spraying 5 times; obtain a glaze-sprayed block.

[0080] Heat the glaze-sprayed block in air atmosphere at a rate of 5°C / min to 1000°C, keep it at this temperature for 1 h, and naturally cool it to room temperature to obtain a high-stability strontium cesium ceramic solidified body, the crystal structure of which is shown inFigure 1 as shown.

[0081] The strontium cesium ceramic solidified body prepared in this example was leached according to the MCC-1 international leaching method, with deionized water as the leaching agent, at 70°C for 21 days. The normalized leaching rate of strontium was 6.23 x 10 -4 g.m -2 . -1 The normalized leaching rate of Cs was 3.67 x 10 - 4 g.m -2 . -1

[0082] Example 3

[0083] 1.8 g of dried aluminum-silicon molecular sieve and 0.2 g of simulated strontium cesium nitrate were weighed out and mixed uniformly; pressed into a φ10 cylindrical pellet at 5 MPa; the cylindrical pellet was heated at a rate of 5°C / min to 700°C in an air atmosphere, and held for 1 h, and naturally cooled to room temperature to obtain primary cesium feldspar; the primary cesium feldspar was crushed and ground, and then pressed into a pellet at 8 MPa, and heated at a rate of 5°C / min to 1000°C in an inert atmosphere (argon), and held for 1 h; naturally cooled to room temperature to obtain secondary cesium feldspar.

[0084] 50 mL of glaze was taken, 0.5 g / L of nickel nitrate was added, 0.5 mL was mixed uniformly, sprayed onto the above-mentioned secondary cesium feldspar, and the spraying was repeated 3 times; a glaze-sprayed body was obtained.

[0085] The glaze-sprayed body was heated at a rate of 5°C / min to 700°C in an air atmosphere, held for 1 h, and naturally cooled to room temperature to obtain a high-stability strontium cesium ceramic solidified body, and the crystal structure is as shown. Figure 1

[0086] The solidified body was leached according to the MCC-1 international leaching method, with deionized water as the leaching agent, at 70°C for 21 days. The normalized leaching rate of strontium was 4.06 x 10 -4 g.m -2 . -1 The normalized leaching rate of Cs was 1.29 x 10 -4 g.m -2 . -1

[0087] Comparative Example 1

[0088] ​​​Take 1.4 g of dry aluminosilicate molecular sieve and 0.6 g of simulated strontium cesium nitrate, mix them uniformly; press the mixture into a φ10 cylindrical pellet under 5 MPa; heat the cylindrical pellet in air atmosphere at a rate of 5°C / min to 1000°C, keep it at this temperature for 1 h, and naturally cool it to room temperature to obtain a solidified body; immerse the solidified body in deionized water as the leaching agent according to the MCC-1 international leaching method, leach it at 70°C for 21 days, the normalized leaching rate of strontium is 3.82×10 -2 g.m -2 .d -1 ; the normalized leaching rate of Cs is 6.25×10 -2 g.m -2 .d -1 .

[0089] Comparative Example 2

[0090] Take 1.6 g of dry aluminosilicate molecular sieve and 0.4 g of simulated strontium cesium nitrate, mix them uniformly; press them into a φ10 cylindrical pellet under 10 MPa; heat the cylindrical pellet in air atmosphere at a rate of 5°C / min to 800°C, keep it at this temperature for 1 h, and naturally cool it to room temperature to obtain a solidified body; immerse the solidified body in deionized water as the leaching agent according to the MCC-1 international leaching method, leach it at 70°C for 21 days, the normalized leaching rate of strontium is 4.78×10 -2 g.m -2 .d -1 ; the normalized leaching rate of Cs is 3.29×10 - 2 g.m -2 .d -1 .

[0091] Comparative Example 3

[0092] Take 1.6 g of dry ZSM-5 molecular sieve and 0.4 g of simulated strontium cesium nitrate, mix them uniformly; press them into a φ10 cylindrical pellet under 10 MPa; heat the cylindrical pellet in air atmosphere at a rate of 5°C / min to 800°C, keep it at this temperature for 1 h, and naturally cool it to room temperature to obtain a solidified body; immerse the solidified body in deionized water as the leaching agent according to the MCC-1 international leaching method, leach it at 70°C for 21 days, the normalized leaching rate of strontium is 3.78×10 -1 g.m -2 .d -1 ; the normalized leaching rate of Cs is 7.89×10 -1 g.m -2 .d -1 .

[0093] From the comparison of the above-mentioned Comparative Examples 1 and 2 and Examples 1 and 2, it can be seen that the solidified body obtained by directly solidifying the simulated strontium cesium nitrate with the aluminum-silicon molecular sieve without spray treatment has a high strontium cesium leaching rate, which is not conducive to the permanent disposal of the radioactive solidified body; from the comparison of Comparative Example 3 and Example 2, it can be seen that the solidified body obtained by solidifying the simulated strontium cesium nitrate with the ZSM-5 molecular sieve has a high leaching rate.

Claims

1. A method for preparing a strontium-cerium ceramic solidification body, comprising the following steps: (1) mixing aluminum-silicon molecular sieve and high-level strontium-cerium waste uniformly, pressing into shape, and calcining to obtain a primary cesium garnet; in step (1), the calcining temperature is 700-800℃; (2) crushing and grinding the primary cesium garnet, pressing into shape, and calcining to obtain a secondary cesium garnet; in step (2), the calcining temperature is 800-1000℃; (3) spraying glaze on the secondary cesium garnet, and then calcining to obtain the strontium-cerium ceramic solidification body; in step (3), the calcining temperature is 700-1000℃. The aluminum-silicon molecular sieve is NaY molecular sieve; the mass percentage of the high-level strontium-cerium waste is 10%-30% based on the total mass of the aluminum-silicon molecular sieve and the high-level strontium-cerium waste; and the glaze is composed of glaze material and nickel nitrate solution. The molar ratio of SiO 2 / Al 2O 3 in the NaY molecular sieve is 4.8-5.6:1; the volume ratio of the glaze material and the nickel nitrate solution is 100:1-2; and the concentration of the nickel nitrate solution is 0.5-1g / L. In step (1), the pressure for pressing into shape is 5-10MPa; the calcining is performed in air atmosphere; the calcining time is 1-2h; and the heating rate of the calcining is 5-10℃ / min. In step (2), the pressure for pressing into shape is 8-10MPa; the calcining is performed in inert atmosphere; the calcining time is 1-2h; and the heating rate of the calcining is 5-10℃ / min. In step (3), the number of times for spraying glaze is 3-5 times; the calcining is performed in air atmosphere; the calcining time is 1-2h; and the heating rate of the calcining is 5-10℃ / min. 7.A method for solidification treatment of high-level waste strontium-cerium, comprising the following steps: (1) mixing aluminum-silicon molecular sieve and high-level strontium-cerium waste uniformly, pressing into shape, and calcining to obtain a primary cesium garnet; in step (1), the calcining temperature is 700-800℃; (2) crushing and grinding the primary cesium garnet, pressing into shape, and calcining to obtain a secondary cesium garnet; in step (2), the calcining temperature is 800-1000℃; (3) spraying glaze on the secondary cesium garnet, and then calcining to obtain the strontium-cerium ceramic solidification body; in step (3), the calcining temperature is 700-1000℃. The aluminum-silicon molecular sieve is NaY molecular sieve; the mass percentage of the high-level strontium-cerium waste is 10%-30% based on the total mass of the aluminum-silicon molecular sieve and the high-level strontium-cerium waste; and the glaze is composed of glaze material and nickel nitrate solution. The molar ratio of SiO 2 / Al 2O 3 in the NaY molecular sieve is 4.8-5.6:1; the volume ratio of the glaze material and the nickel nitrate solution is 100:1-2; and the concentration of the nickel nitrate solution is 0.5-1g / L. In step (1), the pressure for pressing into shape is 5-10MPa; the calcining is performed in air atmosphere; the calcining time is 1-2h; and the heating rate of the calcining is 5-10℃ / min. In step (2), the pressure for pressing into shape is 8-10MPa; the calcining is performed in inert atmosphere; the calcining time is 1-2h; and the heating rate of the calcining is 5-10℃ / min. In step (3), the number of times for spraying glaze is 3-5 times; the calcining is performed in air atmosphere; the calcining time is 1-2h; and the heating rate of the calcining is 5-10℃ / min. ​ ​ ​ ​ ​ 2. The method of claim 1, wherein: ​ ​ ​ 3. The method of claim 2, wherein: ​ ​ 4. The production method according to any one of claims 1 to 3, characterized by: ​ ​ ​ ​ 5. The method of any one of claims 1-3, wherein: ​ ​ ​ ​ 6. The method of any one of claims 1-3, wherein: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 8. The method of claim 7, wherein: ​ ​ ​ 9. The method of claim 8, wherein: ​ ​ 10. The method according to any one of claims 7-9, characterized by: ​ ​ ​ ​ 11. The method according to any one of claims 7-9, characterized by: In step (2), the pressure for the press forming is 8-10 MPa; The calcination is performed in an inert atmosphere; The time for the calcination is 1-2 h; The heating rate for the calcination is 5-10 ℃ / min.

12. The method of any one of claims 7-9, wherein: In step (3), the number of times for the glaze spraying is 3-5 times; The calcination is performed in an air atmosphere; The time for the calcination is 1-2 h; The heating rate for the calcination is 5-10 ℃ / min.

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