Glass ceramic for curing high-calcium high-titanium nuclear waste ash and preparation method thereof

Abstract

The invention provides a glass ceramic for curing high-calcium and high-titanium nuclear waste ash and a preparation method thereof, and belongs to the field of nuclear waste treatment.The glass ceramic is prepared from, by mass, 70-85% of high-calcium and high-titanium nuclear waste ash and 15-30% of inorganic binder; the high-calcium high-titanium nuclear waste ash comprises the following components in percentage by mass: 35-55 wt% of calcium oxide, 15-28 wt% of titanium dioxide, not more than 3 wt% of radioactive element oxide and the balance of other oxides; the inorganic binder is prepared from the following components in percentage by mass: 30 to 40 weight percent of boron oxide, 30 to 40 weight percent of zinc oxide, 15 to 25 weight percent of silicon dioxide and 5 to 15 weight percent of sodium oxide. According to the high-calcium and high-titanium characteristics of the nuclear waste ash, the low-melting-point glass is used as an inorganic binder, the glass ceramic solidified body is successfully prepared through a low-temperature sintering method, and high-temperature migration of nuclides is effectively reduced while the high waste containing rate is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of nuclear waste treatment technology, and in particular to a glass ceramic for solidifying high-calcium and high-titanium nuclear waste ash and its preparation method. Background Technology

[0002] As of the end of 2025, my country had 59 operating nuclear power units, which are expected to generate more than 2,000 m³ of low- and intermediate-level radioactive solid waste annually. Combustible solid nuclear waste accounts for more than 80% of this, mainly including cotton textiles (such as protective clothing), rubber products (such as protective gloves), plastic products (such as polyethylene), and paper products. This type of waste is characterized by its large volume and combustibility. How to safely and efficiently dispose of this type of waste has become one of the key factors restricting the sustainable development of nuclear power in my country.

[0003] Currently, plasma gasification melting technology can effectively reduce the volume of combustible solid nuclear waste and safely solidify toxic elements. This involves using high-temperature plasma to gasify and decompose the organic matter in the waste, thereby significantly reducing its volume. Then, the residual inorganic gasification ash is mixed with glass additives and melted at a high temperature (approximately 1200°C) to form a chemically stable glass solid.

[0004] However, combustible solid nuclear waste comes from a wide range of sources, and the composition of the ash residue produced after its gasification is complex and highly variable. For example, the ash residue from the gasification of cotton textiles and paper products typically contains a high proportion of calcium (more than 50 wt%, as oxides) and titanium (not less than 30 wt%, as oxides). These elements easily lead to crystallization in vitrified products, which not only restricts the optimization design of vitrification formulations and affects the improvement of waste containment, but may also cause blockage at the furnace outlet due to crystallization problems, increasing the risk to safe furnace operation.

[0005] Glass-ceramics have become a promising form of nuclear waste solidification due to their high waste containment capacity, excellent mechanical properties, and chemical stability. There are generally two approaches to preparing glass-ceramic solidifications: one involves fixing the target nuclide within a special crystal structure through high-temperature sintering (>1300℃), then using glass as a binder to encapsulate the nuclide-containing crystals and residual waste within the glass body; the other involves mixing nuclear waste with glass additives, melting it at high temperatures (approximately 1200℃) to prepare a glass body, and then inducing its crystallization through heat treatment to form a glass-ceramic solidification.

[0006] However, whether it is glass curing or glass-ceramic curing, the curing process requires a high temperature (generally ≥1200℃). During the high temperature process, it is very easy to cause the migration risk of volatile nuclides (such as Cs), which reduces the curing efficiency. Summary of the Invention

[0007] In view of this, the present invention proposes a glass ceramic for solidifying high-calcium and high-titanium nuclear waste ash and its preparation method, which is used to solve the problems of low waste containment rate and high heat treatment temperature in the current solidification treatment of high-calcium and high-titanium nuclear waste ash.

[0008] The technical solution of this invention is implemented as follows: This invention provides a glass-ceramic for solidifying high-calcium and high-titanium nuclear waste ash, which, by mass percentage, comprises 70-85 wt% high-calcium and high-titanium nuclear waste and 15-30 wt% inorganic binder; the inorganic components of the high-calcium and high-titanium nuclear waste ash, by mass percentage, include 35-55 wt% calcium oxide, 15-28 wt% titanium dioxide, no more than 3 wt% radioactive element oxides, and 14-50 wt% other oxides; the components of the inorganic binder, by mass percentage, include 30-40 wt% boron oxide, 30-40 wt% zinc oxide, 15-25 wt% silicon dioxide, and 5-15 wt% sodium oxide. Boron oxide, a glass network forger and a fundamental component of glass, significantly reduces glass melting temperature. Zinc oxide, as a glass network intermediate, enhances the chemical stability of glass; however, its high melting point (~1950℃) means that excessive zinc oxide (>40wt%) can raise the glass melting temperature, hindering the melting of low-melting-point glasses. Conversely, zinc oxide <30wt% can impair the glass's leaching resistance, thereby compromising the overall chemical stability of the glass-ceramic. Silica, another glass network forger, enhances the chemical stability of glass. Sodium oxide, a glass network modifier, helps improve the glass melting process and lower the melting temperature. Inorganic glass binders can react with calcium oxide and silica in high-calcium, high-titanium nuclear waste ash to form zinc feldspar (Ca2ZnSi2O7) and promote the formation of CaTiO3. Studies have found that the preferred range for low-melting-point glass as a binder in glass-ceramic cured bodies is 15–25 wt%. Within this mass percentage range, low-melting-point glass as a binder ensures that the glass-ceramic cured body can be sintered at a lower temperature and also ensures that the obtained glass-ceramic cured body has good anti-escape performance for radionuclides. However, when the binder content gradually decreases from 15 wt%, the glass-ceramic cured body is unable to exhibit good curing and anti-escape effects for radionuclides. When its proportion is below 10 wt%, the low-melting-point glass cannot react sufficiently with high-calcium and high-titanium nuclear waste, preventing radionuclides from being effectively cured in the ceramic or glass phase. When the glass binder content gradually increases from 25 wt%, the chemical stability of the glass-ceramic cured body begins to decrease significantly due to the increasing proportion of low-melting-point glass in the glass-ceramic cured body. When the proportion is above 30 wt%, the chemical stability of the glass-ceramic cured body is extremely poor, and it is almost impossible to prevent the leaching of radionuclides that have entered the glass phase.

[0009] Based on the above technical solutions, the preferred method is to include the following by mass percentage: silicon dioxide 10-15 wt%, aluminum oxide 2-7 wt%, sodium oxide 1-4 wt%, magnesium oxide 0-5 wt%, barium oxide 2-5 wt%, zinc oxide 1-3 wt%, iron oxide 0-3 wt%, phosphorus pentoxide 0-2 wt%, potassium oxide 0-1 wt%, boron oxide 0-1 wt%, and sulfur trioxide 0-1 wt%.

[0010] Based on the above technical solutions, the preferred radioactive elements include Cs, Sr, and Co. Because Co... 2+ and Zn 2+ With similar ionic radii (approximately 0.6 Å), Zn is readily replaced by Co in Ca2ZnSi2O7 to form stable Ca2Zn. 1-x Co x The Si₂O₇ phase enables effective solidification of the radioactive nuclide Co. Simultaneously, the glass binder promotes the sintering of high-calcium, high-titanium nuclear waste, forming the CaTiO₃ phase. Ca and Sr have similar ionic radii (approximately 1 Å), and Sr can replace Ca to form a stable Ca²⁺ phase. 1-x Sr x TiO3 phase. In addition, Cs in high-calcium and high-titanium nuclear waste can enter the glass phase, achieving dual solidification of multiple nuclides.

[0011] On the other hand, the present invention provides a method for preparing glass ceramics from solidified high-calcium and high-titanium nuclear waste ash, which is used to prepare the aforementioned glass ceramics from solidified high-calcium and high-titanium nuclear waste ash. The method includes the following steps: Step 1: Prepare raw materials according to the component ratio of the inorganic binder, grind and mix them thoroughly, and then melt them to obtain a glass body as the inorganic binder. Specifically, silicon dioxide and zinc oxide are introduced in the form of oxides, boron oxide is introduced in the form of boric acid, and sodium oxide is introduced in the form of sodium carbonate. After the mixture is thoroughly mixed, it is melted at 1000°C and rapidly cooled to obtain a low-melting-point glass body. The glass body is then crushed and screened to obtain inorganic binder powder with a particle size not exceeding 100 μm. Step 2: Prepare high-calcium and high-titanium nuclear waste and the inorganic binder according to the component ratio of the glass ceramic, and add 1-5 wt% organic binder (the organic binder is polyvinyl alcohol or polyethylene glycol, which enhances the adhesiveness and plasticity of the sample during the molding stage and promotes densification of the sample in subsequent heat treatment). After thorough grinding and mixing, the mixture is molded and pressed, and finally heat-treated to obtain a solidified glass ceramic body. The radioactive elements were introduced in the form of cobalt trioxide, strontium carbonate, and cesium carbonate; the heat treatment temperature was 1000℃.

[0012] Based on the above technical solutions, preferably, in step one, the melting temperature is 900-1050℃ and the melting time is 1-5h. Since the binder adopts a low melting point glass composition design, the required melting temperature is relatively low.

[0013] Based on the above technical solutions, preferably, in step one, the particle size of the glass binder is no greater than 100μm, so as to facilitate the full reaction between the low melting point glass and the waste, thereby reducing the sintering temperature and time of the glass ceramic.

[0014] Based on the above technical solutions, preferably, in step two, the mold pressure is 1500~3200N / m. 2 The holding time is 1 to 10 minutes to ensure the density of the solidified body, so that the low-melting-point glass binder can fully contact the high-calcium and high-titanium nuclear waste and accelerate the reaction.

[0015] Based on the above technical solutions, preferably, in step two, the sintering temperature is 850–1050℃, the holding time is 3–6 hours, and the sample is cooled down with the furnace. Because low-melting-point glass is used as a binder, high-calcium and high-titanium nuclear waste ash can be sintered into a glass-ceramic solidified body at temperatures below 1000℃, making the process simple and efficient.

[0016] The glass-ceramic based on solidified high-calcium and high-titanium nuclear waste ash and its preparation method of the present invention have the following advantages over the prior art: (1) This invention utilizes the characteristics of high calcium and high titanium content in combustible nuclear waste ash residue, uses low melting point glass as a binder, mixes it with high calcium and high titanium nuclear waste ash residue, and then directly sintersects it under low temperature conditions to prepare glass ceramic solidified body. While ensuring high waste containment rate, it effectively inhibits the escape of volatile nuclides.

[0017] (2) The glass-ceramic solidified body prepared by the present invention can simultaneously solidify radionuclides in the glass phase and the ceramic phase, thereby increasing the solidification effect on the nuclides. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 The above are XRD test results of the glass-ceramic cured bodies of Examples 1 and 2 of the present invention. Figure 2 This is an elemental surface scan of the glass-ceramic solidified body of Embodiment 2 of the present invention; Figure 3 The following are the elemental analysis results of different morphological regions of the glass-ceramic solidified body in Example 2 of the present invention; Figure 4The XRD refinement results are shown for the glass-ceramic cured body of Example 2 of the present invention. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1 This embodiment provides a glass-ceramic for solidifying high-calcium and high-titanium nuclear waste, with a total mass of 100g. The components, by mass, are: 85g of high-calcium and high-titanium nuclear waste ash and 15g of inorganic binder. Specifically, the high-calcium and high-titanium nuclear waste ash includes 36.99g CaO (44.52wt% of the total mass of the high-calcium and high-titanium nuclear waste ash), 19.04g TiO2 (22.4wt% of the total mass of the high-calcium and high-titanium nuclear waste ash), 10.33g SiO2, 4.03g Al2O3, 1.68g Na2O, 2.92g MgO, 3.47g BaO, 1.33g ZnO, 0.6g K2O, 0.18g B2O3, 0.31g Fe2O3, 1.22g P2O5, and 2.05g... The SO3 also contains 2.25g of simulated radioactive elements Co2O3, SrO, and Cs2O (3wt% of the total mass of the high-calcium, high-titanium nuclear waste), wherein the radioactive elements Co2O3, SrO, and Cs2O are prepared in an equal weight ratio of 1:1:1. The inorganic binder components include 5.25g B2O3, 5.25g ZnO, 3.00g SiO2, and 1.50g Na2O. In reality, the actual content of radioactive nuclides usually does not exceed 1wt%. The purpose of this embodiment is only to explore whether the glass-ceramic of this application still has a good anti-escape effect under the extreme condition that the radioactive nuclide reaches 3wt% of the total mass of the high-calcium, high-titanium nuclear waste.

[0022] The glass-ceramic in this embodiment is prepared through the following steps: Step 1: Weigh 30g of raw materials according to the inorganic binder formulation design and mix them. SiO2 and ZnO are introduced in oxide form, B2O3 in H3BO3 form, and Na2O in Na2CO3 form. After thoroughly mixing, place the mixture in a 50mL corundum crucible and heat it in a muffle furnace at 1000℃ for 2 hours. Then, quickly remove the crucible and pour the molten glass onto a metal mold. The cooled solid glass is then crushed and screened to obtain glass substrate particles with a particle size not exceeding 80μm.

[0023] Step 2: Weigh 85g of raw materials according to the composition design of high-calcium and high-titanium nuclear waste ash, mix them, and put them into an agate mortar with 15g of inorganic binder and 2g of organic binder polyvinyl alcohol solution (polyvinyl alcohol accounts for 5wt% of the total amount of ash and inorganic binder). Mix thoroughly, then transfer to a stainless steel mold and apply 2250N / m. 2 Press the sample under pressure for 2 minutes to form a sheet, then transfer it to a muffle furnace and heat it to 1000℃ at a rate of 5℃ / min. Hold the temperature for 3 hours and then cool it down with the furnace to obtain a glass-ceramic sample.

[0024] Example 2 This embodiment provides a glass-ceramic for solidifying high-calcium and high-titanium nuclear waste, with a total mass of 100g. The components, by mass, are: 75g of high-calcium and high-titanium nuclear waste ash and 25g of inorganic binder. Specifically, the high-calcium and high-titanium nuclear waste ash includes 32.38g CaO (43.17wt% of the total mass of the high-calcium and high-titanium nuclear waste ash), 16.30g TiO2 (21.73wt% of the total mass of the high-calcium and high-titanium nuclear waste ash), 8.84g SiO2, 3.45g Al2O3, 1.44g Na2O, 2.50g MgO, 2.97g BaO, 1.13g ZnO, 0.52g K2O, 0.15g B2O3, 0.27g Fe2O3, 1.03g P2O5, and 1.77g... The SO3 also contains 2.25g of simulated radioactive elements Co2O3, SrO, and Cs2O (3wt% of the total mass of the high-calcium, high-titanium nuclear waste), wherein the radioactive elements Co2O3, SrO, and Cs2O are prepared in an equal weight ratio of 1:1:1. The inorganic binder components include 8.75g B2O3, 8.75g ZnO, 5.00g SiO2, and 2.50g Na2O. The preparation method differs from that of Example 1 in that no organic binder is added, and the glass-ceramic sintering temperature in step two is 900℃; the rest of the preparation method is the same as that of Example 1.

[0025] Example 3 This embodiment provides a glass-ceramic for solidifying high-calcium and high-titanium nuclear waste, with a total mass of 100g. The components, by mass, are: 75g of high-calcium and high-titanium nuclear waste ash and 25g of inorganic binder. Specifically, the high-calcium and high-titanium nuclear waste ash includes 32.38g CaO (43.17wt% of the total mass of the high-calcium and high-titanium nuclear waste ash), 16.30g TiO2 (21.73wt% of the total mass of the high-calcium and high-titanium nuclear waste ash), 8.84g SiO2, 3.45g Al2O3, 1.44g Na2O, 2.50g MgO, 2.97g BaO, 1.13g ZnO, 0.52g K2O, 0.15g B2O3, 0.27g Fe2O3, 1.03g P2O5, and 1.77g... The SO3 also contains 2.25g of simulated radioactive elements Co2O3, SrO, and Cs2O (3wt% of the total mass of the high-calcium, high-titanium nuclear waste), wherein the radioactive elements Co2O3, SrO, and Cs2O are prepared in an equal weight ratio of 1:1:1. The inorganic binder components include 8.75g B2O3, 8.75g ZnO, 5.00g SiO2, and 2.50g Na2O. The preparation method differs from that of Example 1 in that no organic binder is added, and the glass-ceramic sintering temperature in step two is 1000℃; the rest of the preparation method is the same as that of Example 1.

[0026] Example 4 This embodiment provides a glass-ceramic for solidifying high-calcium and high-titanium nuclear waste, with a total mass of 100g. The components, by mass, are: 80g of high-calcium and high-titanium nuclear waste ash and 20g of inorganic binder. Specifically, the high-calcium and high-titanium nuclear waste ash includes 34.49g CaO (43.17wt% of the total mass of the high-calcium and high-titanium nuclear waste ash), 17.36g TiO2 (21.73wt% of the total mass of the high-calcium and high-titanium nuclear waste ash), 9.42g SiO2, 3.68g Al2O3, 1.53g Na2O, 2.66g MgO, 3.16g BaO, 1.2g ZnO, 0.55g K2O, 0.16g B2O3, 0.29g Fe2O3, 1.10g P2O5, and 1.89g... The SO3 also contains 2.25g of simulated radioactive elements Co2O3, SrO, and Cs2O (3wt% of the total mass of the high-calcium, high-titanium nuclear waste), wherein the radioactive elements Co2O3, SrO, and Cs2O are prepared in an equal weight ratio of 1:1:1. The inorganic binder components include 7.00g B2O3, 7.00g ZnO, 4.00g SiO2, and 2.00g Na2O. The preparation method differs from that of Example 1 in that no organic binder is added, and the glass-ceramic sintering temperature in step two is 1000℃; the rest of the preparation method is the same as that of Example 1.

[0027] Example 5 This embodiment provides a glass-ceramic for solidifying high-calcium and high-titanium nuclear waste, with a total mass of 100g. The components, by mass, are: 85g of high-calcium and high-titanium nuclear waste ash and 15g of inorganic binder. Specifically, the high-calcium and high-titanium nuclear waste ash includes 36.72g CaO (43.17wt% of the total mass of the high-calcium and high-titanium nuclear waste ash), 18.48g TiO2 (21.73wt% of the total mass of the high-calcium and high-titanium nuclear waste ash), 10.02g SiO2, 3.91g Al2O3, 1.63g Na2O, 2.84g MgO, 3.37g BaO, 1.28g ZnO, 0.59g K2O, 0.17g B2O3, 0.31g Fe2O3, 1.17g P2O5, and 2.01g... The SO3 also contains 2.25g of simulated radioactive elements Co2O3, SrO, and Cs2O (3wt% of the total mass of the high-calcium, high-titanium nuclear waste), wherein the radioactive elements Co2O3, SrO, and Cs2O are prepared in an equal weight ratio of 1:1:1. The inorganic binder components include 5.25g B2O3, 5.25g ZnO, 3.00g SiO2, and 1.50g Na2O. The preparation method differs from that of Example 1 in that no organic binder is added, and the glass-ceramic sintering temperature in step two is 1000℃; the rest of the preparation method is the same as that of Example 1.

[0028] Example 6 This embodiment provides a glass-ceramic material for solidifying high-calcium and high-titanium nuclear waste ash, with a total mass of 100g. The components, by mass, are: 75g of high-calcium and high-titanium nuclear waste ash and 25g of inorganic binder. Specifically, the high-calcium and high-titanium nuclear waste ash includes 40.01g CaO (53.35wt% of the total mass of the high-calcium and high-titanium nuclear waste ash), 16.30g TiO2 (21.73wt% of the total mass of the high-calcium and high-titanium nuclear waste ash), 3.34g SiO2, 2.32g Al2O3, 1.34g Na2O, 2.50g MgO, 2.47g BaO, 0.13g ZnO, 0.32g K2O, 1.15g B2O3, 1.17g Fe2O3, 1.03g P2O5, and 0.77g... The SO3 also contains 2.25g of simulated radioactive elements Co2O3, SrO, and Cs2O (3wt% of the total mass of high-calcium, high-titanium nuclear waste ash), wherein the radioactive elements Co2O3, SrO, and Cs2O are prepared in an equal weight ratio of 1:1:1. The inorganic binder components include 10.50g B2O3, 10.50g ZnO, 6.00g SiO2, and 3.00g Na2O. The preparation method is the same as that in Example 1.

[0029] Example 7 This embodiment provides a glass-ceramic material for solidifying high-calcium and high-titanium nuclear waste ash, with a total mass of 100g. The components, by mass, are: 75g of high-calcium and high-titanium nuclear waste ash and 25g of inorganic binder. Specifically, the high-calcium and high-titanium nuclear waste ash includes 32.38g CaO (43.17wt% of the total mass of the high-calcium and high-titanium nuclear waste ash), 25.41g TiO2 (33.88wt% of the total mass of the high-calcium and high-titanium nuclear waste ash), 5.84g SiO2, 1.75g ​​Al2O3, 1.03g Na2O, 1.50g MgO, 1.97g BaO, 0.83g ZnO, 0.32g K2O, 0.15g B2O3, 0.17g Fe2O3, 0.83g P2O5, and 1.57g... The SO3 also contains 2.25g of simulated radioactive elements Co2O3, SrO, and Cs2O (3wt% of the total mass of high-calcium, high-titanium nuclear waste ash), wherein the radioactive elements Co2O3, SrO, and Cs2O are prepared in an equal weight ratio of 1:1:1. The inorganic binder components include 8.75g B2O3, 8.75g ZnO, 5.00g SiO2, and 2.50g Na2O. The preparation method is the same as that in Example 1.

[0030] Example 8 This embodiment provides a glass-ceramic material for curing high-calcium and high-titanium nuclear waste ash, with a total mass of 100g. The components, by mass, are 65g of high-calcium and high-titanium nuclear waste ash and 35g of inorganic binder. Specifically, the proportions of the high-calcium and high-titanium nuclear waste ash and binder are the same as in Example 1. The preparation method is also the same as in Example 1.

[0031] Example 9 This embodiment provides a glass-ceramic material for curing high-calcium and high-titanium nuclear waste ash, with a total mass of 100g. The components, by mass, are: 95g of high-calcium and high-titanium nuclear waste ash and 5g of inorganic binder. Specifically, the proportions of the high-calcium and high-titanium nuclear waste ash and binder are the same as in Example 1. The preparation method is also the same as in Example 1.

[0032] Example 10 This embodiment provides a glass-ceramic material for curing high-calcium, high-titanium nuclear waste ash, with a total mass of 100g. The components, by mass, are: 75g of high-calcium, high-titanium nuclear waste ash and 25g of inorganic binder. Specifically, the proportions of the high-calcium, high-titanium nuclear waste ash and binder are the same as in Example 1. The difference in preparation method compared to Example 1 is that in step two, a 10g sample is subjected to an application of 3200 N / m... 2Press the sample under pressure for 10 minutes to form a sheet, then transfer it to a muffle furnace and heat it to 850°C at a rate of 5°C / min. Hold the temperature for 6 hours and then cool it down with the furnace to obtain a glass-ceramic sample.

[0033] Example 11 This embodiment provides a glass-ceramic material for curing high-calcium, high-titanium nuclear waste ash, with a total mass of 100g. The components, by mass, are: 75g of high-calcium, high-titanium nuclear waste ash and 25g of inorganic binder. Specifically, the proportions of the high-calcium, high-titanium nuclear waste ash and binder are the same as in Example 1. The difference in preparation method compared to Example 1 is that in step two, 10g of sample is taken and subjected to an application of 1500 N / m... 2 Press the sample under pressure for 1 minute to form a sheet, then transfer it to a muffle furnace and heat it to 1050℃ at a rate of 5℃ / min. Hold the temperature for 2 hours and then cool it down with the furnace to obtain a glass-ceramic sample.

[0034] Comparative Example 1 This comparative example provides an existing glass-ceramic for solidifying high-calcium, high-titanium nuclear waste ash, with a total mass of 100g. The components, by mass, are: 85g of high-calcium, high-titanium nuclear waste ash and 15g of glass additives. The formulation of the high-calcium, high-titanium nuclear waste ash and inorganic binder is the same as in Example 1; except for the absence of an organic binder, the preparation method is the same as in Example 1.

[0035] The glass-ceramic samples obtained in the above embodiments and comparative examples were subjected to performance testing. Specifically, the chemical stability of the prepared glass-ceramic cured bodies was evaluated using the internationally recognized product consistency test method "7-day product consistency test (PCT-7) (ASTM C 1285-02)". The test results are shown in Table 1.

[0036] Table 1. Normalized leaching values ​​of each element using PCT-7 (unit: g / m³) 2 )

[0037] The test results show that the leaching values ​​of all items in Examples 1 to 7, 10 and 11 are less than 2 g / m³. 2 Referring to the US standards for the disposal of low active waste solids (elemental PCT-7 normalized leaching value not exceeding 2 g / m³), 2 This indicates that the prepared glass-ceramic has good chemical stability and can effectively solidify simulated nuclides.

[0038] Comparing the PCT-7 normalized leaching results of elements 2 to 7 in Example 1, it can be seen that when the proportion of low melting point glass in the glass-ceramic solidified body is within a suitable range (15wt% or 25wt%), the prepared glass-ceramic has good chemical stability and can effectively solidify simulated nuclides, regardless of whether the nuclear waste ash is in a high calcium (Example 6) or high titanium (Example 7) state.

[0039] A comparison of the elemental PCT-7 normalized leaching results of Examples 1, 8, and 9 shows that when the proportion of low-melting-point glass in the glass-ceramic solidified body is less than 15 wt% or more than 30 wt%, the prepared glass-ceramic solidified body has poor chemical stability.

[0040] Comparing the elemental PCT-7 normalized leaching results of Example 1 with those of Examples 10 and 11, it can be seen that when the proportion of low melting point glass in the glass-ceramic solidified body is within a suitable range (15-30 wt%), the preparation temperature can be reduced to a lower temperature (850°C) by increasing the pressing pressure and extending the holding time during the solidification process.

[0041] A comparison of the elemental normalized leaching results obtained by the PCT-7 method in Example 1 and Comparative Example 1 shows that the prepared glass-ceramic cured bodies exhibit good chemical stability regardless of whether an organic binder is added. However, compared to Comparative Example 1 without an organic binder, the sample in Example 1 with an organic binder shows superior chemical stability.

[0042] Figures 1 to 4 The figures show the XRD and scanning electron microscopy results of the glass-ceramic cured bodies from Examples 1 and 2, respectively. As can be seen from the figures, the glass-ceramic cured body prepared by low-temperature sintering of low-melting-point glass and high-calcium, high-titanium combustible mixed nuclear waste ash can effectively solidify the nuclide into the ceramic phase (Ca2Zn). 0.9 Co 0.1 Si2O7 and Ca 0.98 Sr 0.02 In TiO3 and the glass phase, a dual curing effect of nuclides is achieved, which effectively improves the chemical stability of the glass-ceramic cured body, thereby reducing the nuclide leaching rate.

[0043] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A glass-ceramic material for solidifying high-calcium and high-titanium nuclear waste ash, characterized in that: By weight percentage, it comprises 75–85 wt% high-calcium, high-titanium nuclear waste ash and 15–25 wt% inorganic binder; The components of the high-calcium and high-titanium nuclear waste ash residue, by mass percentage, include: calcium oxide 35-55 wt%, titanium dioxide 15-28 wt%, radioactive element oxides not more than 3 wt%, and the balance being the proportion of other oxides. The inorganic binder comprises, by mass percentage, 30-40 wt% boron oxide, 30-40 wt% zinc oxide, 15-25 wt% silicon dioxide, and 5-15 wt% sodium oxide.

2. The glass-ceramic based on solidified high-calcium, high-titanium nuclear waste ash as described in claim 1, characterized in that: The other oxides, by mass percentage, include 10-15 wt% silicon dioxide, 2-7 wt% aluminum oxide, 1-4 wt% sodium oxide, 0-5 wt% magnesium oxide, 2-5 wt% barium oxide, 1-3 wt% zinc oxide, 0-1 wt% potassium oxide, 0-1 wt% boron oxide, 0-3 wt% iron oxide, 0-2 wt% phosphorus pentoxide, and 0-1 wt% sulfur trioxide.

3. The glass-ceramic of solidified high-calcium and high-titanium nuclear waste ash according to claim 1, characterized in that: The radioactive elements include Cs, Sr, and Co.

4. A method for preparing glass ceramics from solidified high-calcium and high-titanium nuclear waste ash, characterized in that: Used to prepare a glass-ceramic of solidified high-calcium and high-titanium nuclear waste ash as described in any one of claims 1 to 3. Includes the following steps, Step 1: Prepare raw materials according to the component ratio of the inorganic binder, grind and mix them thoroughly, and then melt and cool them to obtain glass, which is the inorganic binder. Step 2: Prepare high-calcium and high-titanium nuclear waste ash and inorganic binder according to the composition ratio of the glass ceramic. After thorough grinding and mixing, add organic binder, press and mold the mixture using a mold, and finally heat treat to obtain the glass ceramic solidified body.

5. The method for preparing glass ceramics from solidified high-calcium and high-titanium nuclear waste ash according to claim 4, characterized in that: In step one, the heat treatment temperature is 900–1050℃ and the heat treatment time is 1–5 hours.

6. The method for preparing glass ceramics from solidified high-calcium and high-titanium nuclear waste ash according to claim 4, characterized in that: In step one, after obtaining the glass melt, the glass melt is rapidly cooled and then crushed to obtain glass particles as an inorganic binder.

7. The method for preparing glass ceramics from solidified high-calcium and high-titanium nuclear waste ash according to claim 6, characterized in that: The glass particles of the inorganic binder have a particle size of no more than 100 μm.

8. The method for preparing glass ceramics from solidified high-calcium and high-titanium nuclear waste ash according to claim 4, characterized in that: In step two, the mold pressure is 1500–3200 N / m. 2 The pressure holding time is 1 to 10 minutes.

9. The method for preparing glass ceramics from solidified high-calcium and high-titanium nuclear waste ash according to claim 4, characterized in that: In step two, the heat treatment temperature is 850–1050℃, and the holding time is 3–6 hours.

10. The method for preparing glass ceramics from solidified high-calcium and high-titanium nuclear waste ash according to claim 4, characterized in that: The organic binder is either polyvinyl alcohol or polyethylene glycol.

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