A low temperature solidification method for silica gel containing radioactive iodine waste

Abstract

The invention discloses a low-temperature solidification method of radioactive iodine waste silica gel, comprising the following steps: S1. mixing aluminum oxide, excess sodium hydroxide, silica gel and deionized water to obtain an alkaline solution containing silicon and aluminum; grinding the radioactive iodine waste silica gel and potassium iodide, adding them to the alkaline solution containing silicon and aluminum under stirring, and continuing to stir to obtain an alkaline mixed slurry; S2. adding the alkaline mixed slurry into a hydrothermal reactor, performing a hydrothermal reaction at 110-150° C., cooling after the hydrothermal reaction, drying, washing, and drying to obtain iodine-containing waste sodalite powder; S3. sintering the iodine-containing waste sodalite powder at 350-550° C. to obtain an iodine-containing waste sodalite solidified body. The invention increases the capacity of radioactive iodine in the sodalite structure by carrying AgI through KI solution, and at the same time, the reaction temperature is low, the sintering and solidification temperature is low, and the decomposition and volatilization of silver iodide and iodine are avoided.

Description

Technical Field

[0001] The invention relates to the technical field of radioactive waste, in particular to a low-temperature solidification method of radioactive iodine-containing waste silica gel. Background Art

[0002] With the country's dual carbon goals and environmental protection needs, relatively clean and reliable nuclear energy will become an important strategic energy source in my country. A large amount of spent fuel will be generated during the operation of the nuclear industry. In the process of spent fuel reprocessing, it needs to go through processes such as cutting, dissolving, separation, collection and solidification. These processes are accompanied by the generation of a large amount of highly radioactive waste liquid. 235 U and 239 Among the fission products of Pu radioactive waste liquid, the mass fraction of iodine and its isotopes accounts for about 0.69%. Radioactive iodine mainly consists of 131 I. 125 I and 129 I, etc., among which 129 The half-life of I is long (T 1 / 2 =1.57×10 7 a) It is easy to spread in the environment. Since iodine is easily enriched in the human thyroid gland, the long-term presence of iodine in the environment will seriously affect human health, so it is necessary to treat and dispose of radioactive iodine waste. The treatment of radioactive iodine is mainly through the use of liquid absorption and solid adsorption methods, but the liquid absorption process is relatively complicated, and the iodine element in the absorption liquid is unstable and easy to diffuse. Solid adsorption has the characteristics of strong adsorption ability, high adsorption capacity and high purification efficiency and is widely used. In the reprocessing of spent fuel, the use of stable silver-attached silica gel to remove radioactive iodine is relatively mature, mainly using the reaction of silver and iodine to generate AgI to achieve the purpose of removing gaseous iodine. After silica gel adsorbs radioactive iodine, it forms radioactive waste containing AgI, which needs to be further treated. Since AgI is easy to decompose and difficult to dissolve, and iodine is easy to migrate, this increases the difficulty of treating and disposing of radioactive iodine waste.

[0003] There are usually three methods for solidifying iodine-containing waste, namely cement solidification, glass solidification and ceramic solidification. Among them, ceramic solidification has better stability and resistance to leaching, and is suitable for solidifying radioactive nuclides with longer lifespans. Sodalite is an aluminosilicate mineral with a cubic crystal system and a cage structure. It can be used to prepare photochromic materials and can also be used in the field of inorganic silicates. The cage of sodalite can be filled with a series of ions. Cl-, OH-, I-, etc. can enter the sodalite cage (SOD or β cage). Sodalite belongs to ceramic solidification. This method allows iodine to enter the crystal structure at a low temperature of no more than 200°C to form Na 4 (AlSiO 4 ) 3 I. Sodalite solidification of radioactive iodine waste can achieve long-term stability of iodine waste solidification body.

[0004] Patents CN 110444310A and CN 111863305A both use radioactive iodine waste as the main substrate of sodalite solidified bodies, and obtain iodine-containing sodalite solidified bodies through hydrolysis and high-temperature sintering. However, the processing temperature in the preparation process is relatively high, and radioactive iodine waste is easy to volatilize and decompose at high temperatures; at the same time, since silver iodide is not easily soluble in water, it is not easy to enter the lattice structure of the system during the preparation process, and a phase separation structure is easy to occur, which cannot ensure the stability of the solidified body, and the sodalite formed has a low capacity for radioactive iodine.

[0005] In summary, the radioactive silver iodide-containing silica gel substrate can be used as the main substrate of the sodalite solidified body to achieve the long-term stability of the iodine waste solidified body, but the radioactive silver iodide in the waste is not easy to dissolve and the decomposition temperature is relatively low (about 558°C), and the treatment temperature in the solidification method adopted in the prior art is relatively high, and the inclusion capacity of the solidified body for silver iodide is not improved. For the solidification treatment of iodine-containing silica gel waste, how to improve the inclusion capacity of the solidified body for silver iodide and perform the solidification treatment at a relatively low temperature is still a problem to be solved. Summary of the invention

[0006] In view of the above-mentioned problems, the purpose of the present invention is to provide a low-temperature solidification method for radioactive iodine waste silica gel. The method mixes the raw materials more evenly, and utilizes the characteristics of silver iodide being easily soluble in potassium iodide solution to achieve more radioactive silver iodide entering the lattice system of sodalite, thereby increasing the solid solution amount of the solidified body; low-temperature synthesis can avoid iodine damage caused by iodine volatilization, and effectively reduce the phase separation of the iodine-containing sodalite solidified body. Radioactive iodine waste silica gel can be directly used as a synthetic substrate for sodalite to achieve the purpose of treating waste with waste, and the obtained iodine-containing waste sodalite solidified body has the characteristics of uniform grain distribution and high purity, and the synthesis process is simple and the raw materials are easily available.

[0007] A low temperature solidification method for silica gel containing radioactive iodine waste comprises the following steps:

[0008] S1. Alumina, excess sodium hydroxide, silica gel and deionized water are mixed to obtain an alkaline solution containing silicon and aluminum; after grinding the silica gel and potassium iodide containing radioactive iodine waste, the silica gel and potassium iodide are added to the alkaline solution containing silicon and aluminum under stirring, and the stirring is continued to obtain an alkaline mixed slurry;

[0009] S2. adding the alkaline mixed slurry obtained in step S1 into a hydrothermal reactor, performing a hydrothermal reaction at 110-150° C., cooling after the hydrothermal reaction, drying after cooling, washing after drying, and continuing to dry after washing to obtain sodalite powder containing radioactive iodine waste;

[0010] S3. The radioactive iodine waste sodalite powder obtained in step S2 is sheeted to obtain a flaky radioactive iodine waste sodalite precursor; and then the flaky radioactive iodine waste sodalite precursor is sintered at 350-550° C. to obtain a radioactive iodine waste sodalite solidified body.

[0011] Among them, it can be known from the fact that the radioactive iodine waste silica gel contains silver iodide and silica gel that the alkaline mixed slurry contains silica gel (SiO 2 ), aluminum oxide (Al 2 O 3 ), sodium hydroxide (NaOH), silver iodide (AgI), potassium iodide (KI) and deionized water. For the present invention, the amount of deionized water added has little effect on the reaction system of the present invention. The present invention does not require the amount of deionized water added, and the amount of deionized water added can be within a reasonable range.

[0012] Preferably, in step S1, the solid content of the alkaline mixed slurry is 100% by total weight, and the SiO 2 The total content of is 20-25%, the content of aluminum oxide is 15-20%, the content of sodium hydroxide is 45-50%, the content of silver iodide is 3-8%, and the content of potassium iodide is 5-10%.

[0013] The total content of silica gel refers to the sum of the content of silica gel in the silica gel containing radioactive iodine waste and the content of added silica gel.

[0014] Preferably, in step S1, the SiO 2 , the molar ratio between aluminum oxide and sodium hydroxide is 2:1:6.

[0015] Preferably, in step S1, the mass ratio between silver iodide and potassium iodide in the alkaline mixed slurry is 1:(1.25-3.33).

[0016] Preferably, in step S1, the grinding time is 0.5 to 1 h, and the stirring time is 18 to 24 h.

[0017] Preferably, in step S2, the time of the hydrothermal reaction is set to 12 to 48 hours.

[0018] Preferably, in step S2, the drying temperature is 105° C., and the drying time is 12 to 18 hours.

[0019] Preferably, in step S2, deionized water is used for washing, and the number of times of washing is 3 to 5 times.

[0020] Preferably, in step S3, the sintering time is set to 2 to 8 hours.

[0021] Preferably, in step S3, when the sheeting is performed, the pressure used is 10-12 MPa, the pressure holding time is 2-5 min, and the diameter of the sheet-shaped sodalite precursor containing radioactive iodine waste is 10 mm.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The invention uses radioactive iodine waste silica gel, aluminum oxide, sodium hydroxide and potassium iodide as raw materials, and adopts a one-step method to directly hydrothermally synthesize iodine-containing waste sodalite. The hydrothermal synthesis is conducive to the synthesis of sodalite. The radioactive silver iodide exists in the hydrothermal reaction in a dissolved manner. The generated sodalite has a stable structure and less phase separation. Moreover, the hydrothermal reaction temperature is not higher than 150° C., thereby avoiding the problem that the reaction temperature is too high and causes iodine to volatilize easily.

[0024] 2. The present invention increases the capacity of radioactive iodine in the sodalite structure by adding potassium iodide and carrying AgI through KI solution; at the same time, Na, Al, Si, Ag, K, and I in the raw materials can enter the cage structure of sodalite, achieving the effect of treating waste with waste.

[0025] 3. The present invention adopts a low-temperature sintering method to obtain a solidified body of sodalite containing radioactive iodine waste, and sintering is performed at a temperature not higher than 550° C., thereby avoiding the decomposition and volatilization of silver iodide and iodine and ensuring the stability of the solidified structure.

[0026] 4. The radioactive iodine-containing waste sodalite prepared by the method of the present invention has high purity, almost no impurity peaks, good cage structure, simple synthesis process and easy to obtain raw materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is an X-ray diffraction analysis diagram of the sodalite powder containing radioactive iodine waste obtained after the hydrothermal reaction of Examples 1 to 3 of the present invention;

[0028] Figure 2 This is a scanning electron microscope (SEM) image of the sodalite powder containing radioactive iodine waste obtained after the hydrothermal reaction in Example 2 of the present invention;

[0029] Figure 3 Scanning electron microscope (SEM) image of the sodalite solidified body containing radioactive iodine waste obtained in Example 2 of the present invention. DETAILED DESCRIPTION

[0030] The present invention is described in further detail below in conjunction with Examples, but embodiments of the present invention are not limited thereto. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art. In addition, about "parts" and "%" in this specification, unless otherwise specified, represent "parts by mass" and "mass %" respectively.

[0031] Example 1

[0032] A low temperature solidification method for silica gel containing radioactive iodine waste comprises the following steps:

[0033] Step 1: Weigh the radioactive iodine waste silica gel, SiO 2 、Al 2 O 3 , NaOH and KI are ready for use. The mass composition of each raw material is SiO 2 (composed of silica gel contained in radioactive iodine waste silica gel and pure silica gel) 22.96 parts, Al 2 O 3 19.48 parts, NaOH 45.87 parts, AgI 3.73 parts (silver iodide contained in radioactive iodine waste silica gel), KI 7.92 parts;

[0034] Step 2: Pretreatment of raw materials for preparing iodine-containing waste silica sodalite

[0035] SiO 2 、Al 2 O 3 Deionized water is added to the mixed components consisting of 2,4-dihydro-1-nitropropene and 2,4-dihydro-1-nitropropene, and NaOH, and the mixture is stirred and mixed until it is completely dissolved to obtain an alkaline solution containing silicon and aluminum; a mixture consisting of silica gel containing radioactive iodine waste and KI is ground for 0.5 h, and after being fully mixed, it is added to the alkaline solution containing silicon and aluminum under stirring, and the stirring is continued for 24 h to obtain a light yellow alkaline mixed slurry;

[0036] Step 3: Preparation of sodalite powder by hydrothermal reaction

[0037] The light yellow alkaline mixed slurry obtained in step 2 is charged into a reactor and reacted at 100°C for 40 hours. After naturally cooling to room temperature, the reactor is opened, the reactor lining is taken out and placed in a 105°C oven to evaporate the supernatant, and then the reactor lining is rinsed three times with deionized water and continued to be dried in a 105°C oven for 12 hours. The product is taken out and ground to obtain sodalite powder containing radioactive iodine waste.

[0038] Step 4: Low temperature curing and sintering

[0039] The radioactive iodine waste sodalite powder obtained in step 3 is tableted using a mold with a diameter of 10 mm, the pressure is 12 MPa, the pressure holding time is 5 min, and the disc is taken out to obtain a disc-shaped sodalite precursor containing radioactive iodine waste; the disc-shaped sodalite precursor containing radioactive iodine waste is placed in a muffle furnace for heat treatment at 550° C. for 2 h, and then cooled to room temperature to obtain a radioactive iodine waste sodalite solidified body.

[0040] Example 2

[0041] A low temperature solidification method for silica gel containing radioactive iodine waste comprises the following steps:

[0042] Step 1: Weigh the radioactive iodine waste silica gel, SiO 2 、Al 2 O 3 , NaOH and KI are ready for use. The mass composition of each raw material is SiO 2 (composed of waste silica gel and pure silica gel contained in radioactive iodine waste silica gel) 22.96 parts, Al 2 O 3 19.48 parts, NaOH 45.87 parts, AgI 3.73 parts (silver iodide contained in radioactive iodine waste silica gel), KI 7.92 parts;

[0043] Step 2: Pretreatment of raw materials for preparing iodine-containing waste silica sodalite

[0044] SiO 2 、Al 2 O 3 Deionized water is added to the mixed components consisting of 2,4-dihydro-1-nitropropene and 2,4-dihydro-1-nitropropene, and NaOH, and the mixture is stirred and mixed until it is completely dissolved to obtain an alkaline solution containing silicon and aluminum; a mixture consisting of silica gel containing radioactive iodine waste and KI is ground for 0.5 h, and after being fully mixed, it is added to the alkaline solution containing silicon and aluminum under stirring, and the stirring is continued for 24 h to obtain a light yellow alkaline mixed slurry;

[0045] Step 3: Preparation of sodalite powder by hydrothermal reaction

[0046] The light yellow alkaline mixed slurry obtained in step 2 is charged into a reactor and reacted at 120°C for 40 hours. After naturally cooling to room temperature, the reactor is opened, the reactor lining is taken out and placed in a 105°C oven to evaporate the supernatant, and then the reactor lining is rinsed three times with deionized water and continued to be dried in a 105°C oven for 12 hours. The product is taken out and ground to obtain sodalite powder containing radioactive iodine waste.

[0047] Step 4: Low temperature curing and sintering

[0048] The radioactive iodine waste sodalite powder obtained in step 3 is tableted using a mold with a diameter of 10 mm, the pressure is 12 MPa, the pressure holding time is 5 min, and the disc is taken out to obtain a disc-shaped sodalite precursor containing radioactive iodine waste; the disc-shaped sodalite precursor containing radioactive iodine waste is placed in a muffle furnace for heat treatment at 550° C. for 2 h, and then cooled to room temperature to obtain a radioactive iodine waste sodalite solidified body.

[0049] Example 3

[0050] A low temperature solidification method for silica gel containing radioactive iodine waste comprises the following steps:

[0051] Step 1: Weigh the radioactive iodine waste silica gel, SiO 2 、Al 2 O 3 , NaOH and KI are ready for use. The mass composition of each raw material is SiO 2 (composed of waste silica gel and pure silica gel contained in radioactive iodine waste silica gel) 22.96 parts, Al 2 O 3 19.48 parts, NaOH 45.87 parts, AgI 3.73 parts (silver iodide contained in radioactive iodine waste silica gel), KI 7.92 parts;

[0052] Step 2: Pretreatment of raw materials for preparing iodine-containing waste silica sodalite

[0053] SiO 2 、Al 2 O 3 Deionized water is added to the mixed components consisting of 2,4-dihydro-1-nitropropene and 2,4-dihydro-1-nitropropene, and NaOH, and the mixture is stirred and mixed until it is completely dissolved to obtain an alkaline solution containing silicon and aluminum; a mixture consisting of silica gel containing radioactive iodine waste and KI is ground for 0.5 h, and after being fully mixed, it is added to the alkaline solution containing silicon and aluminum under stirring, and the stirring is continued for 24 h to obtain a light yellow alkaline mixed slurry;

[0054] Step 3: Preparation of sodalite powder by hydrothermal reaction

[0055] The light yellow alkaline mixed slurry obtained in step 2 is charged into a reactor and reacted at 150°C for 40 hours. After naturally cooling to room temperature, the reactor is opened, the reactor lining is taken out and placed in a 105°C oven to evaporate the supernatant, and then the reactor lining is rinsed three times with deionized water and continued to be dried in a 105°C oven for 12 hours. The product is taken out and ground to obtain sodalite powder containing radioactive iodine waste.

[0056] Step 4: Low temperature curing and sintering

[0057] The radioactive iodine waste sodalite powder obtained in step 3 is tableted using a mold with a diameter of 10 mm, the pressure is 12 MPa, the pressure holding time is 5 min, and the disc is taken out to obtain a disc-shaped sodalite precursor containing radioactive iodine waste; the disc-shaped sodalite precursor containing radioactive iodine waste is placed in a muffle furnace for heat treatment at 550° C. for 2 h, and then cooled to room temperature to obtain a radioactive iodine waste sodalite solidified body.

[0058] Example 4

[0059] A low temperature solidification method for silica gel containing radioactive iodine waste comprises the following steps:

[0060] Step 1: Weigh the radioactive iodine waste silica gel, SiO2 、Al 2 O 3 , NaOH and KI are ready for use. The mass composition of each raw material is SiO 2 (composed of waste silica gel and pure silica gel contained in radioactive iodine waste silica gel) 22.6 parts, Al 2 O 3 19.2 parts, NaOH 45.2 parts, AgI 3 parts (silver iodide contained in radioactive iodine waste silica gel), KI 10 parts;

[0061] Step 2: Pretreatment of raw materials for preparing iodine-containing waste silica sodalite

[0062] SiO 2 、Al 2 O 3 Deionized water is added to the mixed components consisting of 2,4-dihydro-1-nitrogen (2-nitrogen) and 2-nitrogen (2-nitrogen) hydroxide, and the mixture is stirred and mixed until it is completely dissolved to obtain an alkaline solution containing silicon and aluminum; a mixture consisting of silica gel containing radioactive iodine waste and KI is ground for 1 hour, and after being fully mixed, the mixture is added to the alkaline solution containing silicon and aluminum under stirring, and the stirring is continued for 18 hours to obtain a light yellow alkaline mixed slurry;

[0063] Step 3: Preparation of sodalite powder by hydrothermal reaction

[0064] The light yellow alkaline mixed slurry obtained in step 2 is charged into a reactor and reacted at 110°C for 48 hours. After naturally cooling to room temperature, the reactor is opened, the reactor lining is taken out and placed in a 105°C oven to evaporate the supernatant, and then the reactor lining is rinsed three times with deionized water and continued to be dried in a 105°C oven for 12 hours. The product is taken out and ground to obtain sodalite powder containing radioactive iodine waste.

[0065] Step 4: Low temperature curing and sintering

[0066] The radioactive iodine waste sodalite powder obtained in step 3 is tableted using a mold with a diameter of 10 mm, the pressure is 10 MPa, the pressure holding time is 5 min, and the disc is taken out to obtain a disc-shaped sodalite precursor containing radioactive iodine waste; the disc-shaped sodalite precursor containing radioactive iodine waste is placed in a muffle furnace for heat treatment at 350° C. for 8 hours, and then cooled to room temperature to obtain a solidified sodalite containing radioactive iodine waste.

[0067] Example 5

[0068] A low temperature solidification method for silica gel containing radioactive iodine waste comprises the following steps:

[0069] Step 1: Weigh the radioactive iodine waste silica gel, SiO 2 、Al 2 O 3, NaOH and KI are ready for use. The mass composition of each raw material is SiO 2 (composed of waste silica gel and pure silica gel contained in radioactive iodine waste silica gel) 22.6 parts, Al 2 O 3 19.2 parts, NaOH 45.2 parts, AgI 5.28 parts (silver iodide contained in radioactive iodine waste silica gel), KI 7.25 parts;

[0070] Step 2: Pretreatment of raw materials for preparing iodine-containing waste silica sodalite

[0071] SiO 2 、Al 2 O 3 101.7 parts of deionized water are added to the mixed components consisting of 1,2-dihydro-1-nitrogen (2-nitrogen) and 1,4-dihydro-1-nitrogen (2-nitrogen) hydroxide, and the mixture is stirred and mixed until it is completely dissolved to obtain an alkaline solution containing silicon and aluminum; a mixture consisting of silica gel containing radioactive iodine waste and KI is ground for 1 hour, and after being fully mixed, the mixture is added to the alkaline solution containing silicon and aluminum under stirring, and the stirring is continued for 20 hours to obtain a light yellow alkaline mixed slurry;

[0072] Step 3: Preparation of sodalite powder by hydrothermal reaction

[0073] The light yellow alkaline mixed slurry obtained in step 2 is charged into a reactor and reacted at 150°C for 12 hours. After naturally cooling to room temperature, the reactor is opened, the reactor lining is taken out and placed in a 105°C oven to evaporate the supernatant, and then the reactor lining is rinsed three times with deionized water and continued to be dried in a 105°C oven for 18 hours. The product is taken out and ground to obtain sodalite powder containing radioactive iodine waste.

[0074] Step 4: Low temperature curing and sintering

[0075] The radioactive iodine waste sodalite powder obtained in step 3 is tableted using a mold with a diameter of 10 mm, the pressure is 10 MPa, the pressure holding time is 3 minutes, and the disc is taken out to obtain a disc-shaped sodalite precursor containing radioactive iodine waste; the disc-shaped sodalite precursor containing radioactive iodine waste is placed in a muffle furnace for heat treatment at 450° C. for 5 hours, and then cooled to room temperature to obtain a solidified sodalite containing radioactive iodine waste.

[0076] Example 6

[0077] The sodalite solidified bodies containing radioactive iodine waste finally obtained in Examples 1 to 5 were subjected to XRD tests respectively; and the sodalite powder containing radioactive iodine waste and the sodalite solidified bodies containing radioactive iodine waste obtained in Example 2 were characterized in terms of morphology. The obtained SEM images are shown in FIG. Figure 2 and Figure 3 shown.

[0078] After testing, the main diffraction peaks of the products obtained in Examples 1 to 5 appeared at 13.892°, 19.694°, 24.181°, 37.32° and 42.543°.

[0079] Among them, the XRD patterns of the products obtained in Examples 1 to 3 are as follows: Figure 1 As shown. Figure 1 It can be seen that the main diffraction peaks of the product phases obtained in Examples 1 to 3, the peaks appearing at 13.892°, 19.694°, 24.181°, 37.32° and 42.543°, correspond one to one with the standard card containing iodine sodalite. It can be judged that the products obtained in Examples 1 to 3 are solidified sodalite containing radioactive iodine waste Na 4 (AlSiO 4 ) 3 I. Depend on Figure 2 and Figure 3 It can be seen that the diameter of the radioactive iodine waste sodalite powder and the radioactive iodine waste sodalite solidified body prepared in Example 2 is about 7 μm.

[0080] The above embodiments are preferred implementation schemes of the present invention. In addition, the present invention may also be implemented in other ways. Any obvious replacement without departing from the concept of the present invention is within the protection scope of the present invention.

Claims

1. A method for low temperature solidification of silica gel containing radioactive iodine waste, It is characterized in that The steps include: S1. Alumina, excess sodium hydroxide, silica gel and deionized water are mixed to obtain an alkaline solution containing silicon and aluminum; after grinding the silica gel and potassium iodide containing radioactive iodine waste, the silica gel and potassium iodide are added to the alkaline solution containing silicon and aluminum under stirring, and the stirring is continued to obtain an alkaline mixed slurry; S2. adding the alkaline mixed slurry obtained in step S1 into a hydrothermal reactor, performing a hydrothermal reaction at 110-150° C., cooling after the hydrothermal reaction, drying after cooling, washing after drying, and continuing to dry after washing to obtain sodalite powder containing radioactive iodine waste; S3. The radioactive iodine waste sodalite powder obtained in step S2 is sheeted to obtain a flaky radioactive iodine waste sodalite precursor; and then the flaky radioactive iodine waste sodalite precursor is sintered at 350-550° C. to obtain a radioactive iodine waste sodalite solidified body.

2. The low temperature solidification method of silica gel containing radioactive iodine waste according to claim 1, It is characterized in that In step S1, the solid content of the alkaline mixed slurry is calculated by taking the total weight percentage as 100%, and the SiO 2 The total content of the radioactive iodine waste is 20-25%, the content of the aluminum oxide is 15-20%, the content of the sodium hydroxide is 45-50%, the content of the silver iodide contained in the silica gel containing radioactive iodine waste is 3-8%, and the content of the potassium iodide is 5-10%.

3. The low temperature solidification method of silica gel containing radioactive iodine waste according to claim 1, It is characterized in that In step S1, the SiO 2 , the molar ratio between aluminum oxide and sodium hydroxide is 2:1:

6.

4. The low temperature solidification method of silica gel containing radioactive iodine waste according to claim 2, It is characterized in that In step S1, the mass ratio between silver iodide and potassium iodide in the alkaline mixed slurry is 1:(1.25-3.33).

5. The low temperature solidification method of silica gel containing radioactive iodine waste according to claim 1, It is characterized in that Step S1, the grinding time is 0.5-1h, and the stirring time is 18-24h.

6. The low temperature solidification method of silica gel containing radioactive iodine waste according to claim 1, It is characterized in that In step S2, the time of the hydrothermal reaction is set to 12 to 48 hours.

7. The low temperature solidification method of silica gel containing radioactive iodine waste according to claim 1, It is characterized in that In step S2, the drying temperature is set to 105°C, and the drying time is set to 12-18 hours.

8. The low temperature solidification method of silica gel containing radioactive iodine waste according to claim 1, It is characterized in that In step S2, deionized water is used for washing, and the number of washing times is 3 to 5 times.

9. The low temperature solidification method of silica gel containing radioactive iodine waste according to claim 1, It is characterized in that In step S3, the sintering time is set to 2-8 hours.

10. The low temperature solidification method of silica gel containing radioactive iodine waste according to claim 1, It is characterized in that In step S3, when the sheeting is performed, the pressure used is 10-12 MPa, the pressure holding time is 2-5 min, and the diameter of the sheet-shaped sodalite precursor containing radioactive iodine waste is 10 mm.

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