Preparation method of novel titanium-zirconium co-coated nuclide simulant Ce ceramic solidified body

Abstract

The invention discloses a novel titanium and zirconium co-coated nuclide simulant Ce ceramic solidified body which is mainly prepared from TiO2, ZrO2 and CeO2. According to the product, tetravalent actinide elements are simulated by cerium elements, and TiO2 and ZrO2 are good mineral phases of solidified nuclides and belong to a novel ceramic solidified body. Accordingly, the inventor also establishes a corresponding preparation method which comprises the following steps: taking titanium oxide and zirconium oxide as base materials, adding a nuclide simulant cerium oxide, mixing, grinding, carrying out compression molding, and sintering at high temperature. The novel titanium-zirconium co-coated nuclide simulant Ce ceramic solidified body disclosed by the invention has the characteristics of good stability, simple components, strong repeatability and the like; the preparation method disclosed by the invention has the advantages of no complex process, simple process flow, short synthesis period, easiness in engineering and suitability for large-scale application, and the prepared novel TiZrCe ceramic solidified body is stable in property and uniform in element distribution. In conclusion, the method can be used for treating the tetravalent actinide elements in the high-radioactivity waste, and a novel solidification method is provided for solidification of the tetravalent actinide elements.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high-level radioactive nuclear waste solidification, and particularly relates to a preparation method of a novel titanium-zirconium co-coated nuclide simulant Ce ceramic solidification body. BACKGROUND

[0002] With the rapid development of the nuclear energy industry, the safe disposal of high-level radioactive waste has become a global problem. Among them, cerium (Ce) is one of the lanthanide rare earth elements and is also a product of nuclear fission. Because its ionic radius and chemical properties are similar to those of tetravalent actinide elements, it is often used as a chemical simulant of highly radioactive actinide elements (such as plutonium, neptunium, americium, etc.) and is widely used in solidification body performance research. Although Ce itself has relatively low radioactivity, its existence form and migration behavior in nuclear waste have important reference value for evaluating the long-term safety of solidification bodies. Therefore, developing materials that can efficiently and stably solidify Ce is of great significance for promoting the development of high-level waste solidification technology.

[0003] Currently, the solidification treatment of actinide elements mainly adopts deep geological disposal, and the selection of solidification matrix is particularly critical. The mainstream solidification matrices include glass, ceramic and glass-ceramic. Glass solidification technology is relatively mature and has good chemical durability and radiation resistance, but its solubility of actinide elements is limited, and it is in a thermodynamic metastable state, which is prone to phase change or dissolution under extreme conditions such as high temperature, high pressure and underground water erosion for a long time, resulting in increased risk of nuclide leaching. Ceramic solidification bodies, especially titanate-based artificial rocks (such as Synroc series), show better waste loading capacity and long-term stability because they can simulate the stable structure of natural minerals and are considered to be the second generation of high-level waste solidification bodies. Glass-ceramic solidification bodies balance the advantages and disadvantages of the two to some extent, but due to the complexity of the process and the uncertainty of long-term behavior, it is difficult to achieve application in the short term.

[0004] Among the many ceramic solidification bodies, rutile and zirconia are important constituent mineral phases of artificial rock solidification bodies. Rutile itself has good mechanical strength and radiation resistance, and the Ti 4+The tetravalent technetium nuclide fission product has a similar ion radius to the tetravalent technetium, which can fix the technetium ion in the lattice of the rutile, and due to the synthesis of the rutile microcapsule, the solidified body has less heat output and lower long-term leaching performance. The rutile can also optimize the microstructure of the solidified body, reduce the weak links such as glass phase or grain boundary, and thus inhibit the migration of the nuclide. The radiation resistance of zirconia is also excellent, which can form a complete solid solution with plutonium oxide, and is a good mineral phase for solidifying the radioactive nuclide plutonium, and it also helps the solidified body to form a more dense and uniform microstructure, thereby further reducing the specific surface area and the leaching path of the nuclide. Zirconium is also an important element in the artificial rock, and the zirconium-based artificial rock can have a self-annealing effect to resist the amorphization caused by alpha decay, and stabilize the crystal structure of the artificial rock. However, the existing solidification technology still has certain limitations. Although the artificial rock has good solidification performance, the solid solubility is limited, and excessive doping can easily lead to the precipitation of impurity phases, affecting the overall structural stability and leaching resistance. The existing Synroc series formula can be adjusted for different waste compositions, but the synthesis cycle is long, the energy consumption is large, and it is difficult to control the uniformity of the distribution of the nuclide. Therefore, it is urgent to develop a new type of ceramic solidification matrix with simple process, short synthesis cycle, large capacity and good stability. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a preparation method of a new type of titanium-zirconium co-coated nuclide simulant Ce ceramic solidified body, which has the advantages of simple process, short synthesis cycle and easy engineering, and the obtained TiZrCe type ceramic solidified body has good stability, simple composition and strong repeatability.

[0006] To solve the above technical problems, the following technical scheme is adopted in the present application:

[0007] The new type of titanium-zirconium co-coated nuclide simulant Ce ceramic solidified body is mainly made of TiO2, ZrO2 and CeO2.

[0008] The crystal forms of TiO2, ZrO2 and CeO2 are rutile, monoclinic and cubic, respectively.

[0009] The mass percentages of TiO2, ZrO2 and CeO2 in the ceramic solidified body are 40-60%, 25-45% and 1-15%, respectively.

[0010] The mass percentages of TiO2, ZrO2 and CeO2 in the ceramic solidified body are 52.5-57.75%, 29.75-42.5% and 5-12.5%, respectively.

[0011] The preparation method of the above new type of titanium-zirconium co-coated nuclide simulant Ce ceramic solidified body comprises the following steps: mixing and grinding TiO2, ZrO2 and CeO2, pressing into a shape, and high-temperature sintering.

[0012] The preparation method is operated according to the following steps:

[0013] S1: TiO2, ZrO2 and CeO2 are mixed and ground to be uniform, and are pressed to form a solidification precursor;

[0014] S2: the solidification precursor is placed in a muffle furnace and sintered at 1300 DEG C for 24h, and after natural cooling to room temperature, a primary sintered block is obtained, and the primary sintered block is ground and pressed to form a secondary sintered solidification body;

[0015] S3: the secondary sintered solidification body is placed in a muffle furnace and sintered at 1300 DEG C for 24h, and after natural cooling to room temperature, a secondary sintered block is obtained, and the secondary sintered block is ground and pressed to form a tertiary sintered solidification body;

[0016] S4: the tertiary sintered solidification body is placed in a muffle furnace and sintered at 1300 DEG C for 24h, and after air quenching, a novel titanium-zirconium co-coated nuclide analog Ce ceramic solidification body is obtained.

[0017] The pressure for pressing is 10-15 MPa, and the time is 2 min; the heating rate for sintering is 10 DEG C / min; and the grinding is manual grinding in an agate grinding bowl for 20 min.

[0018] The preparation method is applied to the field of treating high-level radioactive waste.

[0019] In view of the problems existing in the solidification of high-level radioactive nuclear waste, the inventor develops a novel titanium-zirconium co-coated nuclide analog Ce ceramic solidification body which is mainly made of TiO2, ZrO2 and CeO2. The product simulates tetravalent actinide elements by using cerium elements, and TiO2 and ZrO2 are good mineral phases for solidifying nuclides, and belong to a novel ceramic solidification body. Accordingly, the inventor also establishes a corresponding preparation method. Titanium oxide and zirconium oxide are used as base materials, and the nuclide analog cerium oxide is added to be mixed and ground, pressed to form, and high-temperature sintered to obtain the product. The novel titanium-zirconium co-coated nuclide analog Ce ceramic solidification body has the characteristics of good stability, simple composition and strong repeatability. The preparation method of the application has no complex process, and has the advantages of simple process flow, short synthesis cycle, easy engineering, suitable for large-scale application, and stable properties of the novel TiZrCe ceramic solidification body and uniform element distribution. In summary, the application can be used for treating tetravalent actinide elements in high-level radioactive waste, and provides a new solidification method for the solidification of tetravalent actinide elements. BRIEF DESCRIPTION OF DRAWINGS

[0020] Fig. 1 The X-ray diffraction pattern of the novel titanium-zirconium co-coated nuclide analog Ce ceramic solidification body prepared in Example 1.

[0021] Fig. 2X-ray diffraction pattern of the new titanium-zirconium co-coated nuclide simulant Ce ceramic solidified body prepared for Example 2.

[0022] Fig. 3 X-ray diffraction pattern of the new titanium-zirconium co-coated nuclide simulant Ce ceramic solidified body prepared for Example 3.

[0023] Fig. 4 X-ray diffraction pattern of the new titanium-zirconium co-coated nuclide simulant Ce ceramic solidified body prepared for Example 4. DETAILED DESCRIPTION

[0024] Example 1

[0025] The following raw materials were prepared in mass percentage: TiO2 56%, ZrO2 34%, CeO2 10%, and all of the above raw materials were powder raw materials.

[0026] 2 g of the mixed powder of the above mass percentage was weighed and placed in an agate mortar and ground for 20 min, mixed uniformly, and then poured into a 1.5 cm diameter circular stainless steel tablet pressing mold, and a uniaxial pressure of 10 MPa was applied for 2 min to obtain a circular solidified precursor with a diameter of 1.5 cm. The above solidified precursor was placed in a muffle furnace and heated to 1300°C at a heating rate of 10°C / min under an air atmosphere, and kept at this temperature for 24 h, and after natural cooling, a primary sintered block was obtained, which was ground and tablet-pressed to form a secondary sintered solidified body. The secondary sintered solidified body was placed in a muffle furnace and heated to 1300°C at a heating rate of 10°C / min under an air atmosphere, and kept at this temperature for 24 h, and after natural cooling to room temperature, the secondary sintered block was ground and tablet-pressed to form a tertiary sintered solidified body. The tertiary sintered solidified body was placed in a muffle furnace and heated to 1300°C at a heating rate of 10°C / min under an air atmosphere and kept for 24 h, and after air quenching, a new titanium-zirconium co-coated nuclide simulant Ce ceramic solidified body was obtained.

[0027] Example 2

[0028] The following raw materials were prepared in mass percentage: TiO2 52.5%, ZrO2 42.5%, CeO2 5%, and all of the above raw materials were powder raw materials.

[0029] The 2 g of mixed powder of the above mass percentage was placed in an agate mortar and ground for 20 min, mixed uniformly, then poured into a 1.5 cm diameter circular stainless steel tabletting mold, under a uniaxial pressure of 10 MPa, pressure maintaining for 2 min, to obtain a circular solidified precursor with a diameter of 1.5 cm. The above solidified precursor was placed in a muffle furnace, heated to 1300℃ at a heating rate of 10℃ / min under air atmosphere, and kept at this temperature for 24 h, and after natural cooling, a primary sintered block was obtained, which was ground and tabletted to form a secondary sintered solidified body. The secondary sintered solidified body was placed in a muffle furnace, heated to 1300℃ at a heating rate of 10℃ / min under air atmosphere, and kept at this temperature for 24 h, and after natural cooling to room temperature, the secondary sintered block was ground and tabletted to form a tertiary sintered solidified body. The tertiary sintered solidified body was placed in a muffle furnace, heated to 1300℃ at a heating rate of 10℃ / min under air atmosphere, and kept at this temperature for 24 h, and after air quenching, a new type of titanium-zirconium co-coated nuclide simulator Ce ceramic solidified body was obtained.

[0030] Example 3

[0031] The following raw materials were prepared according to mass percentage: TiO2 54%, ZrO2 38.5%, CeO2 7.5%, and the above raw materials were all powder raw materials.

[0032] The 2 g of mixed powder of the above mass percentage was placed in an agate mortar and ground for 20 min, mixed uniformly, then poured into a 1.5 cm diameter circular stainless steel tabletting mold, under a uniaxial pressure of 10 MPa, pressure maintaining for 2 min, to obtain a circular solidified precursor with a diameter of 1.5 cm. The above solidified precursor was placed in a muffle furnace, heated to 1300℃ at a heating rate of 10℃ / min under air atmosphere, and kept at this temperature for 24 h, and after natural cooling, a primary sintered block was obtained, which was ground and tabletted to form a secondary sintered solidified body. The secondary sintered solidified body was placed in a muffle furnace, heated to 1300℃ at a heating rate of 10℃ / min under air atmosphere, and kept at this temperature for 24 h, and after natural cooling to room temperature, the secondary sintered block was ground and tabletted to form a tertiary sintered solidified body. The tertiary sintered solidified body was placed in a muffle furnace, heated to 1300℃ at a heating rate of 10℃ / min under air atmosphere, and kept at this temperature for 24 h, and after air quenching, a new type of titanium-zirconium co-coated nuclide simulator Ce ceramic solidified body was obtained.

[0033] Example 4

[0034] The following raw materials were prepared according to mass percentage: TiO2 54%, ZrO2 38.5%, CeO2 7.5%, and the above raw materials were all powder raw materials.

[0035] The 2 g of mixed powder weighed above is placed in a marver mortar and ground for 20 min, mixed uniformly, and then poured into a 1.5 cm diameter circular stainless steel tabletting mold, under a uniaxial pressure of 10 MPa, and pressure is maintained for 2 min, to obtain a 1.5 cm diameter circular solidified precursor. The solidified precursor above is placed in a muffle furnace, heated to 1300 DEG C at a heating rate of 10 DEG C / min under an air atmosphere, and maintained at this temperature for 24 h, and after natural cooling, a primary sintered block is obtained, which is ground and tabletted to form a secondary sintered solidified body. The secondary sintered solidified body is placed in a muffle furnace, heated to 1300 DEG C at a heating rate of 10 DEG C / min under an air atmosphere, and maintained at this temperature for 24 h, and after natural cooling to room temperature, the secondary sintered block is ground and tabletted to form a tertiary sintered solidified body. The tertiary sintered solidified body is placed in a muffle furnace, heated to 1300 DEG C at a heating rate of 10 DEG C / min under an air atmosphere, and maintained at this temperature for 24 h, and after air quenching, a novel titanium-zirconium co-coated nuclide simulator Ce ceramic solidified body is obtained.

[0036] Results: As shown in Figs. 1 to 4 the ceramic solidified body prepared in the present application is mainly a TiZrCe new compound, and has a high degree of crystallization and no other impurity crystals.

Claims

1. A novel titanium zirconium co-coated nuclear isotope simulant Ce ceramic solidified body, characterized by Mainly made of TiO2, ZrO2, CeO2.

2. The ceramic cured body according to claim 1, characterized by: The crystal form of the TiO2, ZrO2, CeO2 is rutile, monoclinic, cubic respectively.

3. The ceramic cured body of claim 1, wherein: The mass percentage of the TiO2, ZrO2, CeO2 in the ceramic solidified body is 40-60%, 25-45%, 1-15% respectively.

4. The ceramic cured body of claim 2, wherein: The mass percentage of the TiO2, ZrO2, CeO2 in the ceramic solidified body is 52.5-57.75%, 29.75-42.5%, 5-12.5% respectively.

5. The method of producing the novel titanium zirconium co-coated nuclide simulating agent Ce ceramic solidified body according to claim 1, characterized by: Mixing, grinding, pressing and high temperature sintering of TiO2, ZrO2, CeO2, and then get.

6. The method of claim 1, wherein The operation is carried out according to the following steps: S1: mixing and grinding TiO2, ZrO2, CeO2 to uniform, pressing and molding, and then get the solidified precursor; S2: placing the solidified precursor in the muffle furnace, sintering at 1300℃ for 24h, and then get the primary sintered block after natural cooling to room temperature, and then grinding and tabletting the primary sintered block to get the secondary sintered solidified body; S3: placing the secondary sintered solidified body in the muffle furnace, sintering at 1300℃ for 24h, and then get the secondary sintered block after natural cooling to room temperature, and then grinding and tabletting the secondary sintered block to get the tertiary sintered solidified body; S4: placing the tertiary sintered solidified body in the muffle furnace, sintering at 1300℃ for 24h, and then get the new type of titanium-zirconium co-coated nuclide simulator Ce ceramic solidified body after air quenching.

7. The method of claim 1, wherein: The pressure of the pressing and molding is 10-15MPa, and the time is 2min; the heating rate of the sintering is 10℃ / min; the grinding is manual grinding in agate mortar for 20min.

8. The use of the preparation method of any one of claims 5-7 in the field of treating high-level radioactive waste.

Images