Radiopharmaceutical waste curing treatment method

Abstract

The invention discloses a radiopharmaceutical waste curing treatment method which comprises the following steps: mixing expanded perlite and alumina powder, putting the mixture into a high-temperature furnace for heating, and carrying out high-temperature melting expansion to form closed-pore spherical vitrified micro-beads; the preparation method comprises the following steps: stirring and mixing closed-pore spherical glass beads, silica fume, nano-silica and an epoxy resin curing agent, and then adding a methylcellulose plasticizer and cerium oxide to form a base material; adding the pre-dried radiopharmaceutical waste into the base material, and uniformly stirring to form a mixture; injecting the mixture into a mold for molding and primary curing, and performing steam curing and environment curing after demolding to obtain a cured body; according to the present invention, the expanded perlite and the alumina powder are subjected to high temperature melting to prepare the closed-pore spherical vitrified micro-bead, the physical adsorption capacity of the porous structure of the closed-pore spherical vitrified micro-bead on the radioactive iodide ion is utilized, and the stable iodide generated by the aluminum element is combined to achieve the chemical bonding so as to reduce the iodine-131 escape problem in the high temperature environment;

Description

Technical Field

[0001] This invention relates to the field of radiopharmaceutical processing technology, and in particular to a method for solidifying radiopharmaceutical waste. Background Technology

[0002] For the solidification treatment of radiopharmaceutical iodine-131 waste, the cement solidification method is usually adopted. This method involves mixing the waste liquid with cement-based materials and fixing the radionuclides in a stable cement matrix through physical encapsulation and chemical coagulation, forming a strong and durable solidified body. This effectively reduces the risk of iodine-131 leakage and the possibility of environmental diffusion, while also facilitating subsequent safe storage and final disposal.

[0003] Traditional curing technologies have significant drawbacks. Existing curing materials are prone to the release of radioactive nuclides (such as iodine-131) under high-temperature conditions, leading to reduced nuclide fixation efficiency and insufficient structural stability of the cured body, potentially causing safety hazards. Due to the high porosity of the material system, it is difficult to effectively block the migration channels of radioactive ions, and the lack of chemical bonding to stabilize nuclides further exacerbates the risk of nuclide release under high-temperature environments.

[0004] Therefore, it is necessary to provide a method for solidifying radiopharmaceutical waste to solve the above-mentioned technical problems. Summary of the Invention

[0005] This invention overcomes the shortcomings of the prior art and provides a method for solidifying radiopharmaceutical waste.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is: a method for solidifying radioactive pharmaceutical waste, comprising the following steps:

[0007] S1. After mixing expanded perlite with alumina powder, put it into a high-temperature furnace and heat it. The heating rate of the high-temperature furnace is 15-25℃ / min. Heat it to 1050-1150℃ and keep it at this temperature for 10-20 seconds to form closed-cell spherical vitrified microspheres through high-temperature melting and expansion.

[0008] S2. Mix closed-cell spherical vitrified microspheres, silica fume, nano silica and epoxy resin curing agent at 280-320 rpm for 10-20 min, and preheat to 130-170℃ simultaneously. Then add methyl cellulose plasticizer and cerium oxide, maintain the temperature at 130-170℃ and stir at 280-320 rpm for 8-1 min to form the base material.

[0009] S3. Add the pre-dried radiopharmaceutical waste to the base material and stir evenly to form a mixture;

[0010] S4. Inject the mixture into the mold to form and initially solidify. After demolding, steam curing and environmental curing are carried out in sequence to obtain the solidified body.

[0011] In a preferred embodiment of the present invention, in step S1, the mass ratio of expanded perlite to alumina powder is 1:0.01-0.03.

[0012] In a preferred embodiment of the present invention, in step S1, the particle size range of the closed-cell spherical vitrified microspheres is 0.1-0.5 mm.

[0013] In a preferred embodiment of the present invention, in step S2, the mass ratio range of each component in the base material is as follows: 50-70% closed-cell spherical vitrified microspheres, 10-20% silica fume, 2-5% nano silica, 1-3% epoxy resin curing agent, 0.5-1.5% methyl cellulose plasticizer, and 0.1-0.5% cerium oxide.

[0014] In a preferred embodiment of the present invention, in step S2, the pre-drying temperature of the radiopharmaceutical waste ranges from 110 to 130°C, and the drying time ranges from 2 to 4 hours.

[0015] In a preferred embodiment of the present invention, in step S3, the preparation temperature of the mixture is controlled within the range of 80-100℃, the stirring speed is controlled within the range of 500-700rpm, and the stirring time is controlled within the range of 15-25min.

[0016] In a preferred embodiment of the present invention, in step S3, the mass ratio of the base material to the radiopharmaceutical waste is 70:30-85:15.

[0017] In a preferred embodiment of the present invention, in step S4, the pressure applied during the molding process is 0.8-1.2 MPa, the heating rate is 4-6 °C / min, the temperature is heated to 170-190 °C, and then held at that temperature for 3-5 hours.

[0018] In a preferred embodiment of the present invention, in step S4, the steam curing temperature after demolding is 85-95°C, and the curing time is 5-10 days.

[0019] In a preferred embodiment of the present invention, in step S4, the temperature range for environmental curing is 20-30℃, the relative humidity is ≥90%, and the curing time is 14-28 days.

[0020] This invention addresses the shortcomings of the prior art and has the following beneficial effects:

[0021] (1) This invention provides a method for solidifying radiopharmaceutical waste. By melting expanded perlite and alumina powder at high temperature to form closed-cell spherical vitrified microspheres, the porous structure of the closed-cell spherical vitrified microspheres is used to physically adsorb radioactive iodide ions, and chemical bonding is achieved by combining the stable iodide generated by aluminum elements, thereby reducing the problem of iodine-131 escape under high temperature environment and significantly improving the radionuclide fixation efficiency. Compared with the iodine escape defect caused by the high porosity of traditional cement solidified bodies, the aluminum-containing microspheres, as the main body of the base material, further reduce the overall porosity of the solidified body through the filling effect of spherical particles, fundamentally improving the safety of waste encapsulation.

[0022] (2) This invention provides a method for solidifying radiopharmaceutical waste. Closed-cell spherical vitrified microspheres physically adsorb and retain iodine ions in the radiopharmaceutical waste through their porous surface structure. At the same time, the aluminum element contained therein forms a stable compound by chemically bonding with iodine, which directly inhibits the high-temperature escape of nuclides from the waste. Silica fume and nano-silica are used as densification filling media, which are embedded in the gaps between the vitrified microspheres to reduce the overall porosity of the solidified body and reduce ion migration channels. The epoxy resin curing agent constructs a continuous encapsulation network under preheating conditions to provide structural constraints for the waste. Cerium oxide stabilizes the high-temperature performance of the substrate, ensuring that the above effects remain effective under thermal conditions.

[0023] (3) This invention provides a method for solidifying radiopharmaceutical waste. By introducing cerium oxide into the base material formulation and adopting a preheating and stirring process, combined with a stepwise solidification strategy of steam curing and high humidity environment curing, the structural stability of the curing agent under high temperature environment is effectively enhanced, solving the problem of performance degradation of conventional materials under high temperature conditions. Furthermore, the gradient curing system simultaneously optimizes the molding quality of the solidified body, ensuring the structural integrity of the final product. Attached Figure Description

[0024] 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 recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a flowchart illustrating a preferred embodiment of the present invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein. Therefore, the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0028] like Figure 1 As shown, the present invention provides a method for solidifying radiopharmaceutical waste, comprising the following steps:

[0029] S1. Mix expanded perlite and alumina powder at a mass ratio of 1:0.01–0.03, put them into a high-temperature furnace and heat them to 1050–1150℃ at a heating rate of 15–25℃ / min. Hold the temperature and foam for 10–20s. After high-temperature melting and expansion, closed-cell spherical vitrified microspheres with a particle size of 0.1–0.5mm are formed.

[0030] It should be noted that: when expanded perlite is mixed with alumina powder at a mass ratio of 1:0.01–0.03, the bound water and volatiles in the expanded perlite vaporize, and the molten glass phase shrinks under the action of surface tension to form a dense shell, ultimately producing closed-cell spherical vitrified microspheres with a particle size of 0.1–0.5 mm.

[0031] Specifically, alumina powder, as a melt modifier, reduces melt viscosity by promoting the depolymerization of silicate networks, enhances fluidity, and ensures uniform bubble distribution. At the same time, it participates in the formation of an aluminum-containing glass phase, improves the strength and thermal stability of the microsphere structure, and ensures that it remains intact at the subsequent base material preparation temperature of 130–170℃.

[0032] Furthermore, the generated closed-pore spherical vitrified microspheres physically adsorb and retain radioactive iodine ions (such as iodine-131) through their porous structure, and utilize the aluminum-containing glass phase to provide reaction sites to form stable compounds (such as aluminum iodide) with iodine, directly inhibiting the high-temperature escape of radionuclides.

[0033] The alumina in the vitrified microspheres reacts with iodide ions (iodine-131) in the radioactive waste to generate stable aluminum iodides (such as AlI3), achieving chemical bonding and fixation.

[0034] The reaction formula for the formation of aluminum iodide (chemical fixation of iodine-131) is: Al2O3 + 3I2 → 2AlI3.

[0035] S2. Add 50–70% closed-cell spherical vitrified microspheres, 10–20% silica fume, 2–5% nano silica, 1–3% epoxy resin curing agent, 0.5–1.5% methyl cellulose plasticizer, and 0.1–0.5% cerium oxide to a mixing device, stir at 280–320 rpm for 10–20 min while preheating to 130–170°C; maintain this temperature and speed and continue stirring for 8–10 min to form a uniform base material.

[0036] It should be noted that stirring the closed-cell spherical vitrified microspheres (50–70%), silica fume (10–20%), nano silica (2–5%) and epoxy resin curing agent (1–3%) at 280–320 rpm for 10–20 min, while preheating to 30–170°C, can ensure that the components are evenly dispersed.

[0037] Among them, silica fume and nano silica fill the gaps between vitrified microspheres, and epoxy resin curing agent begins to build an encapsulation network, providing a structural basis for subsequent curing;

[0038] Furthermore, while maintaining a temperature of 130–170°C and a speed of 280–320 rpm, add methylcellulose plasticizer (0.5–1.5%) and cerium oxide (0.1–0.5%), and continue stirring for 8–10 minutes;

[0039] Among them, methylcellulose enhances the plasticity of the mixture, and cerium oxide stabilizes the high-temperature phase of the substrate through the characteristics of rare earth elements, inhibits the structural deterioration caused by thermal expansion stress, ensures the performance of the cured body under high-temperature conditions, and forms a homogeneous matrix.

[0040] Specifically, through a preheating and stirring process, the closed-pore structure of the vitrified microspheres can physically adsorb iodine ions and the aluminum-containing glass phase (chemically bonded iodine) is completely preserved; silica fume and nano silica further reduce porosity, and epoxy resin curing agent forms a continuous encapsulation network; cerium oxide inhibits high-temperature structural degradation, and the final base material has both radionuclide fixation ability and high-temperature stability, directly solving the problem of iodine-131 escaping at high temperatures.

[0041] S3. After pre-drying the radiopharmaceutical waste at 110–130℃ for 2–4 hours, add it to the base material at a mass ratio of base material to waste material of 70:30–85:15, and stir at 500–700 rpm for 15–25 minutes at 80–100℃ to form a mixture.

[0042] It should be noted that: after pre-drying the radiopharmaceutical waste at 110–130℃ for 2–4 hours to remove free moisture, it is added to the base material prepared by S2 at a mass ratio of base material:waste = 70:30–85:15 to start the mixing process. Pre-drying prevents moisture from interfering with the curing reaction and ensures that the waste particles are in full contact with the base material;

[0043] Furthermore, the mixture is stirred at 500–700 rpm for 15–25 minutes at 80–100℃. The high temperature maintains the fluidity of the base material, and the high-speed shear force makes the radioactive waste (containing iodine-131 and other nuclides) uniformly dispersed into the base material. The pore surface of the vitrified microspheres directly adsorbs the waste particles and iodine ions, while the silica fume and nano silica fill the gaps, initially forming a dense mixture.

[0044] Specifically, by controlling the temperature and rotation speed, premature curing of the epoxy resin is avoided, and the radioactive waste is physically encapsulated by the pores of the vitrified microspheres in the base material, with the aluminum-containing phase reserving chemical bonding sites. At the same time, cerium oxide stabilizes the high-temperature structure.

[0045] S4. Inject the mixture into the mold, apply a pressure of 0.8–1.2 MPa, heat to 170–190℃ at a heating rate of 4–6℃ / min and keep at that temperature for 3–5 hours to complete the initial curing; after demolding, cure in steam at 85–95℃ for 5–10 days, and then transfer to an environment at 20–30℃ and relative humidity ≥90% for 14–28 days to finally obtain the cured body.

[0046] It should be noted that: the mixture is injected into the mold and pressure of 0.8–1.2 MPa is applied. It is heated to 170–190°C at a heating rate of 4–6°C / min and then held at that temperature for 3–5 hours to complete the initial curing. The pressure forces the mixture to densely fill the mold and eliminate air bubbles. Simultaneous heating triggers the epoxy resin crosslinking reaction to form a rigid network, locking the radioactive waste and the base material into an integral structure.

[0047] Furthermore, after demolding, the product is cured in steam at 85–95℃ for 5–10 days. The high temperature and high humidity environment drives the silica fume and nano-silica to undergo a pozzolanic reaction, generating calcium silicate hydrate (CSH) gel to fill the gaps between the vitrified microspheres, further reducing porosity and blocking the migration channels of iodide ions. Cerium oxide simultaneously stabilizes the high-temperature phase, suppresses the thermal expansion stress of the structure, and improves the integrity of the cured body.

[0048] The reaction formula for the formation (densification and filling) of hydrated calcium silicate gel (CSH) is as follows:

[0049] CaO+SiO2+H2O→CaO·SiO2·H2O;

[0050] Furthermore, by curing in an environment of 20–30℃ and ≥90% relative humidity for 14–28 days, the epoxy resin network is fully cured, and the CSH gel continues to grow and become denser. This gradient curing strategy ultimately forms a triple barrier—the adsorption and fixation of nuclides through the pores of vitrified microspheres, the encapsulation and isolation by epoxy resin, and the blocking of migration channels by the low-porosity matrix, thus completely solving the problem of iodine-131 escaping at high temperatures.

[0051] Example 1

[0052] A method for solidifying radiopharmaceutical waste includes the following steps:

[0053] S1. After mixing expanded perlite and alumina powder at a mass ratio of 1:0.02, the mixture is put into a high-temperature furnace and heated to 1100℃ at a heating rate of 20℃ / min. The mixture is then kept at this temperature for 15s to foam and form closed-cell spherical vitrified microspheres with a particle size of 0.3mm through high-temperature melting and expansion.

[0054] S2. Add 60% by mass of closed-cell spherical vitrified microspheres, 15% of silica fume, 3.5% of nano silica, 2% of epoxy resin curing agent, 1% of methyl cellulose plasticizer and 0.3% of cerium oxide to a mixing device, stir at 300 rpm for 15 min and preheat to 150°C simultaneously, maintain this temperature and speed and continue stirring for 10 min to form a uniform base material;

[0055] S3. After pre-drying the radiopharmaceutical waste at 120℃ for 3 hours, add it to the base material at a mass ratio of 80:20 and stir at 600 rpm for 20 minutes at 90℃ to form a mixture.

[0056] S4. Inject the mixture into the mold, apply a pressure of 1.0 MPa, heat to 180°C at a heating rate of 5°C / min and keep warm for 4 hours to complete the initial curing. After demolding, cure in 90°C steam for 7 days, and then transfer to an environment of 25°C and 95% relative humidity for 21 days to finally obtain the cured body.

[0057] Example 2

[0058] This embodiment is basically the same as embodiment 1, except that in step S1, the mass ratio of expanded perlite to alumina powder is 1:0.01.

[0059] Example 3

[0060] This embodiment is basically the same as Embodiment 1, except that in step S1, the mass ratio of expanded perlite to alumina powder is 1:0.025.

[0061] Example 4

[0062] This embodiment is basically the same as Embodiment 1, except that in step S1, the mass ratio of expanded perlite to alumina powder is 1:0.03.

[0063] Example 5

[0064] This embodiment is basically the same as Embodiment 1, except that in step S2, 50% by mass of closed-cell spherical vitrified microspheres, 15% of silica fume, 3.5% of nano silica, 2% of epoxy resin curing agent, 1% of methyl cellulose plasticizer and 0.3% of cerium oxide are added to the stirring device, stirred at 300 rpm for 15 minutes and preheated to 150°C at the same time, and stirred for another 10 minutes while maintaining the temperature and speed to form a uniform base material.

[0065] Example 6

[0066] This embodiment is basically the same as Embodiment 1, except that in step S2, 65% by mass of closed-cell spherical vitrified microspheres, 12.75% of silica fume, 3.25% of nano silica, 1.95% of epoxy resin curing agent, 0.95% of methyl cellulose plasticizer and 0.15% of cerium oxide are added to a stirring device, stirred at 300 rpm for 15 minutes and preheated to 150°C simultaneously, and stirred for another 10 minutes while maintaining this temperature and speed to form a uniform base material.

[0067] Example 7

[0068] This embodiment is basically the same as Embodiment 1, except that in step S2, 70% by mass of closed-cell spherical vitrified microspheres, 12% of silica fume, 3% of nano silica, 1.8% of epoxy resin curing agent, 0.9% of methyl cellulose plasticizer and 0.3% of cerium oxide are added to the stirring device, stirred at 300 rpm for 15 minutes and preheated to 150°C simultaneously, and stirred for another 10 minutes while maintaining this temperature and speed to form a uniform base material.

[0069] Example 8

[0070] This embodiment is basically the same as embodiment 1, except that in step S3, the mass ratio of the base material to the radiopharmaceutical waste is 70:30.

[0071] Example 9

[0072] This embodiment is basically the same as embodiment 1, except that in step S3, the mass ratio of the base material to the radiopharmaceutical waste is 85:15.

[0073] Example 10

[0074] This embodiment is basically the same as embodiment 1, except that in step S3, the mass ratio of the base material to the radiopharmaceutical waste is 82.5:17.5.

[0075] Comparative Example 1

[0076] This embodiment is basically the same as embodiment 1, except that in step S1, pure expanded perlite is put into a high-temperature furnace and heated to 1100°C at a heating rate of 20°C / min. It is then kept at this temperature for 15 seconds to foam and form closed-cell spherical vitrified microspheres with a particle size of 0.3 mm through high-temperature melting and expansion.

[0077] Comparative Example 2

[0078] This embodiment is basically the same as Embodiment 1, except that in step S2, 15% silica fume, 3.5% nano silica, 2% epoxy resin curing agent, 1% methyl cellulose plasticizer and 0.3% cerium oxide are added to the mixing equipment, stirred at 300 rpm for 15 minutes and preheated to 150°C at the same time, and stirred for another 10 minutes at the same temperature and speed to form a uniform base material.

[0079] Comparative Example 3

[0080] This embodiment is basically the same as embodiment 1, except that in step S2, 60% by mass of closed-cell spherical vitrified microspheres, 15% of silica fume, 3.5% of nano silica, 2% of epoxy resin curing agent, and 1% of methyl cellulose plasticizer are added to the mixing equipment and stirred at 300 rpm for 15 minutes while simultaneously preheating to 150°C. The temperature and speed are maintained and stirring is continued for 10 minutes to form a uniform base material.

[0081] Experimental Example

[0082] Experimental objective: To compare the curing effects of the solidified bodies in Examples 1-10 and Comparative Examples 1-3 on radiopharmaceutical waste (taking iodine-131 as an example).

[0083] Experimental methods:

[0084] Iodine Escape Rate Test: Simulating high temperature conditions (150℃), the amount of iodine-131 escaped from the cured body was measured;

[0085] Porosity determination: The porosity of the solidified body was determined using the mercury intrusion porosimetry method;

[0086] Structural stability assessment: The mechanical and thermal properties of the cured body are evaluated through compressive strength testing and coefficient of thermal expansion determination.

[0087] Experimental procedures (results are shown in Table 1)

[0088] Sample preparation: Cured body samples (13 groups in total) were prepared according to the processes of Examples 1-10 and Comparative Examples 1-3. Three parallel samples were prepared for each group to ensure data reliability.

[0089] Iodine leaching rate test: The sample was placed in a high-temperature furnace (150℃) and heated continuously for 6 hours. The concentration of leached iodine-131 was measured using an iodine ion detector.

[0090] Formula for calculating the escape rate:

[0091] Porosity determination: The porosity (total porosity and closed-pore ratio) of the sample was determined using a mercury porosimeter.

[0092] Structural stability assessment:

[0093] Compressive strength test: The compressive strength (MPa) of the sample was determined using a universal testing machine;

[0094] Thermal expansion coefficient determination: The thermal expansion coefficient (×10) of the sample was measured using a thermomechanical analyzer (TMA). -6 / ℃).

[0095] Table 1:

[0096]

[0097]

[0098] As shown in Table 1:

[0099] Example 1 exhibits the best performance in all performance indicators, with the lowest iodine escape rate (0.85%), the lowest porosity (5.22%), the highest compressive strength (45.67 MPa), and the lowest coefficient of thermal expansion (1.12).

[0100] The mass ratio of expanded perlite to alumina powder of 1:0.02 ensures a good foaming structure of vitrified microspheres while providing enough aluminum to chemically bond with iodine-131 to form a stable compound, effectively inhibiting the escape of radionuclides.

[0101] The 60% vitrified microspheres serve as the main body, providing physical adsorption sites and reducing porosity through spherical particle filling; the synergistic effect of silica fume and nano-silica further densifies the matrix; the epoxy resin curing agent constructs a robust encapsulation network; the crucial 0.3% cerium oxide significantly enhances the material's high-temperature stability; the 80:20 base material to waste ratio ensures sufficient encapsulation capacity while achieving a high waste load; combined with pressure molding and gradient curing processes, a dense and highly stable triple-barrier cured body is ultimately formed.

[0102] Compared with Example 1, Examples 2 to 4 adjusted the mass ratio of expanded perlite to alumina powder in step S1 to 1:0.01, 1:0.025 and 1:0.03, respectively.

[0103] As the alumina ratio decreased or increased, the properties of the cured body showed a downward trend. In Example 2 (1:0.01), due to insufficient alumina content, the amount of aluminum-containing glass phase formed was reduced, resulting in weakened chemical bonding ability, an increase in iodine escape rate to 1.02%, and a corresponding increase in porosity and coefficient of thermal expansion.

[0104] Example 3 (1:0.025) shows performance close to that of Example 1, indicating that there is a better performance range around 1:0.02;

[0105] In Example 4 (1:0.03), the excessive alumina altered the melt properties, affecting the uniform foaming and structural integrity of the vitrified microspheres. This resulted in a significant increase in porosity to 6.63%, a decrease in compressive strength, and an iodine leaching rate of 1.15%, indicating that an excessively high alumina ratio was actually detrimental to the overall performance improvement.

[0106] In Examples 5 to 7, the proportion of the base material was adjusted in step S2, with a focus on the influence of the vitrified microsphere content;

[0107] As the proportion of vitrified microspheres decreased from 60% to 50% (Example 5) or increased to 70% (Example 7), and other components were adjusted accordingly, the performance was slightly inferior to that of Example 1.

[0108] Example 5 (50% vitrified microspheres) suffered from a reduced content of functional main components, weakened physical adsorption and skeletal support, resulting in a porosity as high as 7.14%, a compressive strength of 38.45 MPa, and an iodine escape rate of 1.32%.

[0109] Although Example 7 (70% vitrified microspheres) has a low porosity (5.33%), the excessively high proportion of vitrified microspheres encroaches on the space of the dense fillers such as silica fume and nano silica and the epoxy resin encapsulation network, resulting in the material's overall performance failing to surpass that of Example 1. Its compressive strength is 44.89 MPa, which is slightly lower than that of Example 1.

[0110] The performance of Example 6 (65% vitrified microspheres) falls between the two, indicating that a vitrified microsphere content of around 60% is more conducive to the synergistic effect of the components in the current system.

[0111] In Examples 8 to 10, the mass ratio of the base material to radiopharmaceutical waste was adjusted in step S3 to 70:30, 85:15, and 82.5:17.5, respectively, to investigate the effect of waste loading on performance. As the proportion of waste increased (i.e., the proportion of base material decreased), the performance of the solidified body decreased significantly.

[0112] In Example 8 (70:30), due to the reduced proportion of base material, there was a relative lack of material used for adsorption, encapsulation, and the formation of a dense structure, resulting in a porosity increase to 6.92%, a compressive strength decrease to 37.88 MPa, and an iodine release rate increase to 1.20%. Although the waste material ratios of Examples 9 (85:15) and 10 (82.5:17.5) were lower than those of Example 1 (80:20), their performance data were even worse.

[0113] Comparative Example 1 uses pure expanded perlite to prepare vitrified microspheres, which are completely lacking in alumina. Therefore, it is impossible to achieve chemical bonding and fixation of aluminum and iodine. Its iodine escape rate is as high as 2.15%, porosity is 9.87%, and compressive strength is only 28.33 MPa, which fully demonstrates the indispensability of alumina in improving the efficiency of nuclide fixation and structural performance.

[0114] Comparative Example 2 completely omitted the vitrified microspheres, losing the core functions of physical adsorption, chemical bonding and particle filling, resulting in high porosity, low strength and overall performance degradation.

[0115] Although Comparative Example 3 contains vitrified microspheres, it lacks cerium oxide. Its coefficient of thermal expansion is as high as 1.55, its compressive strength is 32.10 MPa, and its iodine release rate is 1.82%, indicating that cerium oxide plays a key role in stabilizing the high-temperature performance of the substrate, suppressing thermal stress, improving the overall structural integrity, and enhancing the ability to fix nuclides.

[0116] The results of the three comparative examples collectively highlight the necessity and superiority of the synergistic effect of the components in this invention.

[0117] In summary, Example 1 outperformed other examples and comparative examples in terms of iodine evaporation rate, porosity, and structural stability, demonstrating that its process parameters (such as the mass ratio of vitrified microspheres to alumina powder of 1:0.02 and the base material ratio of 60:15:3.5:2:1:0.3) were optimized.

[0118] Comparative Examples 1-3 showed significantly deteriorated performance due to the lack of key components (alumina powder, cerium oxide, etc.), further verifying the importance of Example 1.

[0119] Based on the preferred embodiments of the present invention described above, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for solidifying radiopharmaceutical waste, characterized in that, Includes the following steps: S1. After mixing expanded perlite with alumina powder, put it into a high-temperature furnace and heat it. The heating rate of the high-temperature furnace is 15-25℃ / min. Heat it to 1050-1150℃ and keep it at this temperature for 10-20 seconds to form closed-cell spherical vitrified microspheres through high-temperature melting and expansion. S2. Mix closed-cell spherical vitrified microspheres, silica fume, nano silica and epoxy resin curing agent at 280-320 rpm for 10-20 min, and preheat to 130-170℃ simultaneously. Then add methyl cellulose plasticizer and cerium oxide, maintain the temperature at 130-170℃ and stir at 280-320 rpm for 8-1 min to form the base material. S3. Add the pre-dried radiopharmaceutical waste to the base material and stir evenly to form a mixture; S4. Inject the mixture into the mold to form and initially solidify. After demolding, steam curing and environmental curing are carried out in sequence to obtain the solidified body.

2. The method for solidifying radiopharmaceutical waste according to claim 1, characterized in that: In S1, the mass ratio of expanded perlite to alumina powder is 1:0.01-0.

03.

3. The method for solidifying radiopharmaceutical waste according to claim 1, characterized in that: In S1, the particle size range of the closed-cell spherical vitrified microspheres is 0.1-0.5 mm.

4. The method for solidifying radiopharmaceutical waste according to claim 1, characterized in that: In S2, the mass ratio range of each component in the base material is as follows: 50-70% closed-cell spherical vitrified microspheres, 10-20% silica fume, 2-5% nano silica, 1-3% epoxy resin curing agent, 0.5-1.5% methyl cellulose plasticizer, and 0.1-0.5% cerium oxide.

5. The method for solidifying radiopharmaceutical waste according to claim 1, characterized in that: In step S2, the pre-drying temperature of the radiopharmaceutical waste ranges from 110 to 130°C, and the drying time ranges from 2 to 4 hours.

6. The method for solidifying radiopharmaceutical waste according to claim 1, characterized in that: In S3, the preparation temperature of the mixture is controlled within the range of 80-100℃, the stirring speed is controlled within the range of 500-700rpm, and the stirring time is controlled within the range of 15-25min.

7. The method for solidifying radiopharmaceutical waste according to claim 1, characterized in that: In S3, the mass ratio of the base material to the radiopharmaceutical waste is 70:30-85:

15.

8. The method for solidifying radiopharmaceutical waste according to claim 1, characterized in that: In S4, the pressure applied during the molding process is 0.8-1.2 MPa, the heating rate is 4-6 °C / min, the temperature is heated to 170-190 °C, and then held for 3-5 hours.

9. The method for solidifying radiopharmaceutical waste according to claim 1, characterized in that: In S4, the steam curing temperature after demolding is 85-95℃, and the curing time is 5-10 days.

10. A method for solidifying radiopharmaceutical waste according to claim 1, characterized in that: In S4, the temperature range for environmental curing is 20-30℃, the relative humidity is ≥90%, and the curing time is 14-28 days.

Images