CN101549965B - A cement-based solidified material for processing middle and low radioactive incineration ash and a method for processing middle and low radioactive incineration ash - Google Patents

Abstract

The invention discloses a cement-based solidified material for processing medium and low radioactivity incineration ash and a method for processing medium and low radioactivity incineration ash. The solidified material is obtained by using slag, fly ash, zeolite, metakaolin, and cement clinker as materials to be activated, and is obtained by mixing uniformly with an activator after grinding, and a liquid activator or a composite solid activator can be used. Using the cured material, the material to be excited can be mixed with the activator, according to the containment capacity of 30-40%, mixed with incineration ash according to the curing operation, stirred and maintained until solidified. The cement-based solidified material of the present invention can be used to prepare a nuclear waste solidified body with an incineration ash inclusion capacity greater than 30%, stable mechanical properties, and a low nuclide ion leaching rate, especially when solidifying plutonium-containing waste, ^{the 239} Pu leaching rate is 42 days. 10 ^{-6 ~ 7} cm/d. The invention will play an important role in the treatment of medium and low radioactivity incineration ash, and has broad application prospects.

Description

A cement-based solidified material for processing medium and low radioactive incineration ash and a method for processing medium and low radioactive incineration ash

technical field

The invention relates to a solidified material for treating radioactive waste, in particular to a cement-based solidified material for treating medium and low radioactive burning ash and its application in treating medium and low radioactive burning ash.

Background technique

Due to the application and research of nuclear science and nuclear technology in science, medicine, industry and military affairs, a large amount of radioactively polluted plastic, paper, work clothes, gloves and other wastes with medium and low radioactivity and flammability are produced every year. In order to eliminate the hidden danger of leakage of radioactive substances caused by mildew and fire, etc., it is necessary to incinerate and reduce the volume to generate a stable form that is easy to dispose of - incineration ash.

However, incineration cannot change the radioactivity of the waste. How to properly and strictly manage the radioactive incineration ash so that it does not leak into the biosphere is not only a purely scientific and technical problem, but has become an international political and social issue. question. At present, on the issue of radioactive waste treatment, all countries in the world have formed a relatively consistent opinion, that is, the radioactive waste should be solidified first, and then the solidified package should be placed in the bedrock with good water transport performance in deep strata. The interbody filling has good blocking performance on radionuclides, and forms a long-term effective isolation of radionuclides and the biosphere based on the principle of multiple obstacles.

The solidification methods of radioactive waste mainly include cement method, asphalt method, plastic method, glass method, ceramic method and so on. The cement solidification method has been successfully used for the solidification of low- and medium-level radioactive waste due to its simple equipment and process, no need for high temperature, low one-time investment, no waste gas purification problem, easy-to-obtain raw materials, and stable hydration products. However, the cement solidified body prepared by the conventional process is a porous material, and the nuclide leaching rate is high, and some components are unfavorable to the cement hydration, which affects the performance of the solidified body and the improvement of the inclusion capacity. Due to its low porosity, high strength, and complete hydration, the alkali-gelled material has a good blocking effect on radionuclide adsorption and long-term stability. It is an ideal radioactive waste solidification material and has increasingly become a research hotspot.

At present, a lot of research has been done on the solidification of cement-based materials for low- and medium-level radioactive waste at home and abroad, from using traditional Portland cement, aluminate cement or adding silica fume, slag, and fly ash to Portland cement. Mixed materials such as cement are developed in the direction of portland cement-clay mineral composite system, alkali-activated cementitious material system, alkali slag-clay composite cementitious material and hydrothermal synthetic material.

But there are still the following problems:

(1) The waste bag capacity is low (about 20%);

(2) The nuclide leaching rate is relatively high, especially the solidification effect on plutonium-containing waste is relatively poor;

(3) The mechanism of nuclide ion solidification needs further study;

(4) Most of the domestic research stays in the simulated solidification stage, and seldom conducts real waste solidification treatment;

(5) The hydration product of the solidified body needs to be further optimized to enhance the solidification effect on nuclides.

In addition, there are few studies on the solidification of low- and medium-radiation incineration ash. The composition and properties of incineration ash seriously affect the improvement of the inclusion capacity of the solidified body and the solidification effect of nuclide ions. For example, a. When CaO is mixed in the ash, it reacts with water to form Ca(OH) ₂ , which releases a large amount of heat, expands the volume by 97.9%, and generates local stress, resulting in poor stability of the solidified body; b. When the ash is mixed with When there are PbO, ZnO, CuO, etc., these metal oxides will delay the hydration reaction of cement; c. When metals such as Mg, Al, Zn, Sn, and Pb are mixed in the ash, the alkaline components in the cement will be The reaction with these metals will cause hydrogen gas to be released during the placement of the cured product, which will cause cracks in the cured product and even damage the packaging container. Therefore, it is of great significance for the safe management of radioactive waste to develop new cement solidification materials, improve the containment capacity of incineration ash and the comprehensive physical and chemical properties of the solidified body.

Contents of the invention

The invention provides a cement-based solidified material for treating medium- and low-radioactive incineration ash with large waste containment capacity, stable mechanical properties and low nuclide ion leaching rate.

In order to solve the problems of the technologies described above, the present invention takes the following technical solutions:

A cement-based solidified material for processing medium and low radioactive incineration ash. The material to be activated is composed of ground slag, fly ash, zeolite, metakaolin and cement clinker, mixed with an activator evenly, and cured and solidified. obtained modified cement.

Wherein: the metakaolin is calcined at low temperature; the cement clinker is Huaxin PI 52.5 cement clinker or benchmark cement high-quality cement clinker.

Among them: the slag, fly ash, zeolite, metakaolin, and cement clinker are respectively ground to 400-500±20m ² /Kg, 400-500±20m ² /Kg, 100-300 mesh, 1000-1500 mesh , 400～500±20m ² /Kg powder; the weight and number ratio of the slag, fly ash, zeolite, metakaolin and cement clinker is 40～70:10～20:10～30:10～35 : 4-20.

Wherein: in order to improve the mechanical properties of cement, 0 to 6 parts by weight of polymer latex powder are also added in the cement-based solidified material; when adding, the amount of polymer latex powder is included in the weight of the cement-based solidified material powder, preferably at 100 The cement-based curing material powder contains 4-6 parts by weight of polymer latex powder.

Among them: in order to improve the fluidity and impermeability of cement, the cement-based solidified material is also added with 0-0.8 parts by weight of Nai series water reducer FDN; when adding, the amount of water reducer FDN is included in the cement-based solidified material powder In the weight of the material, it is preferable to contain 0.3-0.8 parts by weight of the Nai series high-efficiency water reducer in 100 parts by weight of the cement-based solidified material powder.

In the above cement-based solidified material: the activator is a liquid activator, the liquid activator is water glass with n being 1.2-1.8, and the addition amount is 5-10% of the weight of the cement-based solidified material powder.

Alternatively, the activator is a composite solid activator, which is composed of 15-35 parts by weight of sodium silicate, 55-75 parts by weight of sodium sulfate and 5-15 parts by weight of calcium hydroxide. The dosage of the agent is included in the weight of the cement-based solidified material powder, and 5-10 parts by weight of the solid activator are contained in 100 parts by weight of the cement-based solidified material powder.

The second object of the present invention is to provide a method for treating medium and low radioactive incineration ash.

The method for processing medium and low radioactive incineration ash provided by the present invention is to use the cement-based solidified material of the present invention, mix the material to be excited, polymer latex powder, and Nai series water reducer FDN with the activator, and mix them by 30-40 % containment capacity, mix with incineration ash according to the curing operation, stir, and cure until solidified.

In the above-mentioned method for treating medium and low radioactive incineration ash, when using a solid activator, directly mix the materials to be energized, polymer latex powder and nano-based water reducing agent FDN with the solid activator, and mix the mixture for 20 ± 2 minutes before mixing with the solid activator. The incineration ash is mixed with water and stirred, cured until solidified.

When using a liquid activator, directly mix and stir the material to be energized, polymer latex powder and nano-based water reducer FDN with incineration ash and liquid activator, stir for 15±2min and then cure until solidification.

The invention provides a new cement-based solidified material for treating medium and low radioactivity incineration ash. The cement-based solidified material of the invention can obtain a incineration ash containing capacity greater than 30%, stable mechanical properties, and low nuclide ion leaching rate The leaching rate of ²³⁹ Pu is less than 1.0×10 ^-6 cm/d in 42 days when solidified nuclear waste is solidified, especially when plutonium-containing waste is solidified. The cement-based solidified material of the present invention has the characteristics of large waste storage capacity, stable mechanical properties, and low nuclide ion erosion rate ( ²³⁹ Pu), and its preparation process has no chemical pollution sources, no radioactivity, no light pollution, and no noise. The invention will play an important role in the treatment of medium and low radioactivity incineration ash, and has broad application prospects.

The present invention will be described in further detail below in conjunction with specific embodiments.

Description of drawings

Figure 1 is a process flow chart of using a solid activator to treat medium and low radioactive incineration ash

Figure 2 is a process flow chart of using a liquid stimulant to treat medium and low radioactive incineration ash

Detailed ways

In order to solve the problems of small waste containment capacity and high nuclide ion leaching rate of existing cement-based solidified materials, the present invention obtains the optimal cement-based radionuclide solidified material by adopting simulated solidification treatment optimization and then real solidification treatment optimization.

The cement-based solidified material (also known as modified cement) for treating medium and low radioactive incineration ash in the present invention is at least prepared from the material to be excited and the activator, and other admixtures can also be added during the preparation.

Here, the material to be excited is obtained by grinding and mixing slag, fly ash, zeolite, metakaolin and cement clinker as raw materials. Metakaolin is calcined at low temperature; cement clinker is preferably high-quality cement clinker, such as Huaxin P I 52.5 cement clinker, benchmark cement clinker; grinding requirements: slag 400～500±20m ² /Kg, fly ash 400 ～500±20m ² /Kg (preferably 450±20m ² /Kg), zeolite 100～300 mesh (preferably 200 mesh), metakaolin 1000～1500 mesh (preferably 1250 mesh), cement clinker 400～500± 20m ² /Kg (preferably 450±20m ² /Kg).

When the materials to be excited are mixed and used, the ratio of parts by weight of slag, fly ash, zeolite, metakaolin and cement clinker is 38-70:10-15:10-30:10-35:4-15. By introducing high-performance cement clinker, low-temperature calcined metakaolin and zeolite to modify the base material, the obtained hydration products are mainly calcium silicate hydrate and zeolite with low Ca/Si, which have relatively strong nuclide ions. Strong chemical curing, which greatly enhances the nuclide ion curing effect of cement-based curing materials. The follow-up experiment results of the present invention show that under the condition of high inclusion capacity (30%-40%), when plutonium-containing waste is solidified, the leaching rate of ²³⁹ Pu is less than 1.0×10 ^-6 cm/d in 42 days.

In the present invention, the activator is divided into a liquid activator and a solid activator: wherein, the liquid activator has Na ₂ O.nSiO ₂ as the main component, and n is 1.2 to 1.8 (depending on the curing material), which can be purchased from Beijing Hongxing Guangsha Chemical Building Materials Co., Ltd., the amount of liquid activator added is 5-10% of the weight of powder materials (including materials to be energized, admixtures, and water reducers); solid activators are based on sodium silicate, sodium sulfate , Calcium hydroxide is the main ingredient, and the formula is by weight: 15-35 parts of sodium silicate, 55-75 parts of sodium sulfate, 5-15 parts of calcium hydroxide (depending on the curing material), per 100 parts by weight 5-10 parts by weight of the solid activator are added to the composition of the cement-based solidified material (without water, including the material to be energized, the solid activator itself, an admixture, and a water reducing agent). The purpose of adding the activator is to stimulate the potential active components of the material to be excited to produce gelation. The mechanism of action is: under the action of alkali and water (that is, by means of chemical energy), the polymerized Si- O-Si or Al-O-Al bonds are cracked (but not necessarily depolymerized into monomers), and then the depolymerized substances with a low degree of polymerization are polymerized into another material with a different composition and degree of polymerization. High and gelling hydrate.

In addition, in order to improve the mechanical properties of cement, admixtures, such as polymer latex powder, can also be added in the cement-based solidified material. When adding polymer latex powder, its consumption is included in the cement-based solidified material powder (including the In the total amount of material, solid activator, admixture itself and water reducer), 4-6 parts by weight of polymer latex powder can be added to every 100 parts by weight of cement-based solidified material powder. The purpose of introducing polymer latex powder into the cement curing substrate is to modify it: on the one hand, the solid bonding mechanism between the polymer emulsified film and the cement hydration product is used to toughen the solidified body, which significantly improves the curing effect. The impact resistance of the solidified body; on the other hand, the micro-bubbles introduced into the solidified body by the latex powder are used to optimize the pore structure of the solidified body, which significantly improves the freeze-thaw damage resistance of the solidified body. The mechanical properties of the cement solidified body have been improved to a higher level, so as to better ensure the safe operation, transportation and final disposal of the incinerated ash solidified body.

In order to improve the fluidity and impermeability of cement, a high-efficiency water reducer (such as Nai series high-efficiency water reducer FDN) can also be added to the cement-based solidified material. In the total amount of powder (including materials to be activated, solid activator, admixture and water reducer itself), 0.3-0.8 parts by weight of water reducer can be added per 100 parts by weight of cement-based solidified material composition.

The present invention adopts two experimental methods of simulated curing treatment optimization and real curing treatment optimization when optimizing the composition of each component.

1) Simulated solidification disposal optimization: study the chemical composition, mineral composition and performance of real radioactive incineration ash, and use garbage ash, non-radioactive nuclides and other special components (such as CaO, ZnO, etc.) to prepare simulations similar to real incineration ash Incineration ash; and use the assembled modified cement for simulated solidification treatment, according to the test results, feedback and adjust the modified cement preparation technology and process suitable for the simulated ash, and then adjust the composition of the modified cement;

2) Real solidification disposal optimization: 1) The optimized modified cement combination is used to solidify the real radioactive incineration ash, and the cement preparation technology and process are re-optimized according to the performance test results to determine the final cement preparation technology and process parameters. Determine the optimal mix of cement-based setting materials.

The method for solidifying medium and low radioactive incineration ash by using the cement-based solidified material for treating medium and low radioactive incineration ash according to the present invention may include the following steps:

1) Grinding: Grinding the raw material to be excited;

2) Mixing: put the materials to be excited and the solid activator into the mixer, and mix them evenly;

3) Curing: According to the set volume, mix with incineration ash according to the curing operation, stir and cure until solidified.

In the above preparation method, in the step 2), the corresponding mixing time is set according to the characteristics of the materials, and the mixing time of the solid activator and the material to be energized is set at 20±2min.

If polymer latex powder or water reducing agent is added, it is completed in step 2).

If a liquid activator is used, step 2) is omitted, and the solid raw materials (materials to be energized and incineration ash) and the liquid activator are directly mixed at the same time, stirred and cured until solidified. The mixing and stirring time of the liquid activator and other solid raw materials is set at 10±2min.

The present invention is further illustrated below with specific examples. The following examples 1-12 adopt the best experimental scheme of the present invention, and those of ordinary skill in the art can obviously think of some similarities and alternatives according to the disclosure of the present invention, which should all belong to the disclosure of the present invention. The methods used in the examples are conventional methods unless otherwise specified.

Embodiment 1, preparation and solidification effect of cement-based solidified material for processing medium and low radioactive incineration ash

As shown in Figure 1, a solid activator is used to prepare a cement-based solidified material and perform solidification treatment.

Grinding: Grinding raw materials, including slag, zeolite, low-temperature calcined metakaolin and Huaxin P I 52.5 cement clinker (Portland cement), respectively grinding to 400±20m ² /Kg, 100 mesh, 1000 Mesh, 400±20m ² /Kg.

Ingredients and Mixing:

Get 4.97Kg slag, 1.5Kg zeolite, 1.5Kg metakaolin and 0.7Kg cement clinker after grinding, then get 0.5Kg polymer latex powder and 0.8Kg self-made composite solid activator (by the silicic acid of 15 parts by weight) Sodium, 75 parts of sodium sulfate and 10 parts of calcium hydroxide), put it into the mixer, and add 0.03kg of high-efficiency water reducer (Nai series high-efficiency water reducer FDN) and mix evenly. The time is 20±2min to obtain modified cement B1;

Get 3.95Kg slag after grinding, 2.0Kg zeolite, 2.5Kg metakaolin, 0.5Kg cement clinker, 0.5Kg polymer latex powder and 1.0Kg self-made composite solid activator (by parts by weight being 25 parts of sodium silicate, 70 parts of sodium sulfate and 5 parts of calcium hydroxide) were put into the mixer, and 0.05kg of high-efficiency water reducer (Nai series high-efficiency water reducer FDN) was added and mixed evenly, and the mixing time was 20 ±2min to obtain modified cement B2;

Preparation of simulated incineration ash:

According to the chemical composition, mineral composition and performance of the real radioactive incineration ash, the simulated incineration ash similar to the real incineration ash is prepared by using garbage ash, non-radioactive simulated nuclide and other special components (such as CaO). 6.45kg, 0.05kg of simulated nuclide cesium Cs and 3.5kg of CaO are loaded into the mixer, and the mixing time is 25±2min;

Simulated solidification treatment: carry out simulated solidification treatment to simulated incineration ash with modified cement B1 and B2 obtained in step 2), according to the ratio of 30wt% incineration ash and 70wt% cement-based solidified material, add water and stir in the mixer according to the solidification operation Prepare a Φ50mm×50mm sample, and maintain it to the corresponding age at a temperature of 25±5°C, in accordance with GB 14569.1-93 "Performance Requirements for Low and Medium Level Radioactive Waste Solidified Body-Cement Solidified Body" and GB 7023-86 "Long-term leaching test of solidified radioactive waste" conducted various performance tests, and the results are shown in Table 1.a.

Table 1.a Test results of cement solidified body simulated incineration ash

serial number   Compressive strength/MPa Impact resistance Freeze-thaw resistance Soak resistance Leaching rate of ¹³⁷ Cs(42d) B1 38.4 qualified qualified qualified 2.3×10 ^-4 cm/d B2 26.5 qualified qualified qualified 7.6×10 ^-5 cm/d

It can be seen from Table 1.a that at 30% inclusion capacity, the properties of B1 and B2 modified cement solidified bodies all meet the performance requirements of GB 14569.1-93, and the leaching rate of ¹³⁷ Cs (42d) is lower than 10 ^-3 cm /d (If the requirements are not met, the parameters of the modified cement need to be adjusted).

The above experimental results also suggest that the modified cement of the present invention has a better effect in simulated curing treatment.

Real solidification disposal: use B1 and B2 modified cement for solidification disposal of real radioactive incineration ash, 30wt% real radioactive incineration ash (taken from China Academy of Engineering Physics, where the activity of Cs is 10 ^{5 ~ 6} Bq) and 70wt% % The proportion of cement-based solidified materials, according to the solidification operation, add water to the mixer and prepare a Φ50mm×50mm sample, and maintain it to the corresponding age at a temperature of 25±5°C, according to GB 14569.1-93 "Low, Medium Table 1.b shows the performance test results of the horizontal radioactive waste solidified body performance requirements - cement solidified body" and GB 7023-86 "long-term leaching test of radioactive waste solidified body".

Table 1.b Test results of cement solidified body of real radioactive incineration ash

serial number   Compressive strength/MPa Impact resistance Freeze-thaw resistance Soak resistance Leaching rate of ¹³⁷ Cs(42d) B1 32.5 qualified qualified qualified 1.8×10 ^-4 m/d B2 21.0 qualified qualified qualified 6.5×10 ^-5 m/d

It can be seen from Table 1.b that at 30% inclusion capacity, the properties of B1-B2 modified cement solidified bodies all meet the performance requirements of GB 14569.1-93, and the leaching rate of ¹³⁷ Cs(42d) is lower than 10 ^-3 cm /d (If the requirements are not met, the parameters of the modified cement need to be adjusted). It can be seen that the modified cements B1-B2 can solidify and dispose of real high-calcium incineration ash better.

Embodiment 2, preparation and detection of cement-based solidified material for processing medium and low radioactive incineration ash

As shown in Figure 2, the liquid activator cement-based solidified material was prepared.

Grinding: Grinding slag, fly ash, zeolite, and Huaxin P I 52.5 cement clinker to 500±20m ² /Kg, 450±20m ² /Kg, 200 mesh, 450±20m ² /Kg;

Mixture:

Take 6.0Kg slag, 1.5Kg fly ash, 1.5Kg zeolite and 1.0Kg Huaxin P I 52.5 cement clinker and mix evenly to obtain material A1 to be activated;

Get 6.5Kg slag, 1.0Kg fly ash, 2.0Kg zeolite and 0.5Kg Huaxin P I 52.5 cement clinker and mix evenly to obtain material A2 to be excited;

Get 5.5Kg slag, 1.0Kg fly ash, 3.0Kg zeolite and 0.5Kg Huaxin P I 52.5 cement clinker and mix evenly to obtain the material to be excited A3;

According to high metal oxide incineration ash (from China Academy of Engineering Physics, wherein the activity of Cs is 10 ^{5 ~ 6} Bq), liquid activator (water glass with M=1.4, purchased from Beijing Hongxing Guangsha Chemical Building Materials Co., Ltd. company) accounted for 35% and 5% (calculated as Na ₂ O) of the weight of the material to be stimulated, respectively, added to the mixer to prepare a Φ50mm×50mm sample, and cured to the corresponding age at a temperature of 25±5°C According to GB 14569.1-93 "Performance Requirements for Low and Medium Level Radioactive Waste Solidified Body - Cement Solidified Body" and GB 7023-86 "Long-term Leaching Test of Radioactive Waste Solidified Body", the test results are shown in Table 2.

Table 2 Performance test results of high metal oxide incineration ash cement solidified body

serial number   Compressive strength/MPa Impact resistance Freeze-thaw resistance Soak resistance Leaching rate of ¹³⁷ Cs(42d) A1 52.2 qualified qualified qualified 2.0×10 ^-4 m/d A2 37.5 qualified qualified qualified 4.5×10 ^-4 cm/d A3 25.8 qualified qualified qualified 1.2×10 ^-4 cm/d

It can be seen from Table 2 that when A1-A3 are used in combination with liquid activators, all properties of the cured body meet the performance requirements of GB14569.1-93, and the leaching rate of ¹³⁷ Cs(42d) is 10 ^{- 4} cm/d, it can solidify and dispose of high metal oxide incineration ash well.

Embodiment 3, preparation and detection of cement-based solidified material for processing medium and low radioactive incineration ash

Grinding: Grinding slag, zeolite, metakaolin and reference cement clinker (purchased from Beijing Xingfa Cement Co., Ltd.) to 400±20m ² /Kg, 300 mesh, 1500 mesh and 500±20m ² /Kg respectively;

Mixture:

Take 6.55Kg of slag, 1.5Kg of zeolite, 1.5Kg of metakaolin, 0.4Kg of reference cement clinker and 0.05kg of Nai series high-efficiency water reducer FDN and mix evenly to obtain material C1;

Take 6.65g of slag, 1.2g of zeolite, 1.2Kg of metakaolin, 0.5Kg of polymer latex powder, 0.4Kg of reference cement clinker and 0.05kg of Nai series high-efficiency water reducer FDN and mix them uniformly to obtain material C2;

Get 6.02Kg slag, 1.5Kg zeolite, 1.5Kg metakaolin, 0.4Kg high-performance cement clinker and 0.5Kg composite solid activator (by weight 35 parts of sodium silicate, 55 parts of sodium sulfate and 10 parts of calcium hydroxide ) and 0.08kg of Nai series high-efficiency water reducer FDN were evenly mixed to obtain modified cement C3;

Get 5.22Kg slag, 1.4Kg zeolite, 1.4Kg metakaolin, 0.5Kg polymer latex powder, 0.4Kg benchmark cement clinker and 1.0Kg composite solid activator (by weight parts being 20 parts of sodium silicate, 65 parts of Sodium sulfate and 15 parts of calcium hydroxide) and 0.08kg of Nai series high-efficiency water reducer FDN were mixed uniformly to obtain modified cement C4.

The content of incineration ash is 40%, conventional ash (taken from China Academy of Engineering Physics, Pu activity is 10 ^{6 ~ 7} Bq). Wherein C1 and C2 adopt liquid stimulant, and the water glass of M=1.6 is purchased from Beijing Hongxing Guangsha Chemical Building Materials Co., Ltd., and the dosage is 5% (Na ₂ O), and the sample to be tested is prepared according to Example 2 . For C3 and C4, composite solid activators were used, and samples to be tested were prepared according to Example 1. Cured to the corresponding age in an environment with a temperature of 25±5°C, according to GB 14569.1-93 "Performance Requirements for Low and Medium Level Radioactive Waste Solidified Body - Cement Solidified Body" and GB 7023-86 "Long-term Leaching Test for Radioactive Waste Solidified Body "Carry out various performance tests, the results are shown in Table 3.

Table 3 Test results of incineration ash cement solidified body

serial number   Compressive strength/MPa Impact resistance Freeze-thaw resistance Soak resistance Leaching rate ²³⁹ Pu(42d) C1 35.2 qualified qualified qualified 7.0×10 ^-7 m/d C2 23.4 qualified qualified qualified 5.0×10 ^-7 cm/d C3 28.7 qualified qualified qualified 5.6×10 ^-6 cm/d C4 15.2 qualified qualified qualified 2.5×10 ^-7 cm/d

It can be seen from Table 3 that the properties of the cured body formed by using C1-C4 all meet the performance requirements of GB 14569.1-93. At 40% inclusion capacity, the leaching rate of ²³⁹ Pu(42d) is 10 ^-6 cm/d, It can solidify and dispose of conventional incineration ash better.

Examples 4-12, preparation and detection of cement-based solidified materials for processing medium and low radioactive incineration ash

Prepare the cement-based solidified material that handles medium and low radioactive incineration ash with the method for embodiment 1～2, raw material ratio is shown in Table 4, and incineration ash dosage is 35%, conventional ash (taken from Chinese Academy of Engineering Physics, Pu's The activity is 10 ^{5 ~ 6} Bq). And in accordance with GB 14569.1-93 "Performance Requirements for Low and Medium Level Radioactive Waste Solidified Body - Cement Solidified Body" and GB 7023-86 "Long-term Leaching Test of Radioactive Waste Solidified Body", among them, the incineration ash cement solidified body test The results are shown in Table 5.

Table 4 Raw material ratio of cement solidified base material (kg)

instance number slag fly ash Zeolite Metakaolin latex powder Cement clinker Water reducer FDN liquid stimulant   Solid activator 4 4.85 - 1.5 2.5 0.6 0.5 0.05 1.0 - 5 5..45 - 1.5 2.1 0.4 0.5 0.05 0.8 - 6 4.95 1.0 1.0 2.0 0.5 0.5 0.05 0.6 - 7 4.45 1.0 1.9 1.5 0.6 0.5 0.05 0.5 - 8 5.55 - 3.0 1.0 0.4 - 0.05 0.6 - 9 3.92 - 3.0 - 0.5 1.5 0.08 - 1.0 10 3.42 - - 3.5 0.5 1.5 0.08 - 1.0 11 6.22 - 2.5 - 0.4 - 0.08 - 0.8 12 6.02 1.0 - 1.5 0.4 - 0.08 - 1.0

Remarks: The amount of liquid activator added is 5-10% of the weight of the powder material, and it is not included in the powder material itself.

Table 5 Test results of incineration ash cement solidified body

instance number Compressive strength/MPa Impact resistance Freeze-thaw resistance Soak resistance Leaching rate ²³⁹ Pu(42d) 4 47.1 qualified qualified qualified 3.5×10 ^-6 m/d 5 49.4 qualified qualified qualified 2.4×10 ^-6 cm/d 6 44.2 qualified qualified qualified 5.5×10 ^-6 cm/d 7 38.4 qualified qualified qualified 3.6×10 ^-6 m/d 8 24.5 qualified qualified qualified 3.8×10 ^-6 m/d 9 27.1 qualified qualified qualified 2.0×10 ^-6 cm/d 10 32.2 qualified qualified qualified 1.5×10 ^-6 cm/d 11 56.6 qualified qualified qualified 2.9×10 ^-6 cm/d 12 50.8 qualified qualified qualified 1.2×10 ^-6 cm/d

It can be seen from Table 5 that the various properties of the cured body obtained from the materials of Examples 4-12 all meet the performance requirements of GB 14569.1-93. It can be seen that the cured materials formed in Examples 4-12 have a 35% inclusion capacity. The leaching rate of ²³⁹ Pu(42d) is 10 ^-6 cm/d, which can be well solidified and disposed of conventional incineration ash.

Comparative experiment: Preparation and detection of cement-based solidified materials for conventional treatment of medium and low radioactive incineration ash

Low-alkalinity alkali slag cement (denoted as AK1) and alkali slag-clay composite cement (denoted as AK2) were used for comparative experiments.

Low-alkalinity alkali slag cement AK1 uses slag, fly ash, sodium sulfate and gypsum as raw materials, among which slag and fly ash are ground to 500m ² /kg and 460m ² /kg respectively, and sodium sulfate and gypsum are industrial grade. The raw materials are weighed and mixed uniformly according to the weight ratio of 68%, 18%, 4% and 10%.

Alkali slag-clay composite cement AK2 uses slag, zeolite, metakaolin and attapulgite clay as raw materials, and the materials are 500m ² /kg, 180 mesh, 800 mesh and 200 mesh respectively. The raw materials are weighed and mixed uniformly according to the weight ratio of 70%, 5%, 15% and 10%. The cement uses water glass with a modulus of M=2.3 as an activator, and is added in 5% by weight (calculated as Na ₂ O).

According to the proportion of 35% incineration ash (conventional ash, taken from China Academy of Engineering Physics, Pu activity is 10 ^{6 ~ 7} Bq) and 65% cement-based solidified material, add water in the mixer and prepare a Φ50mm×50mm sample 1. Cured to the corresponding age in an environment with a temperature of 25±5°C, according to GB 14569.1-93 "Performance Requirements for Low and Medium Level Radioactive Waste Solidified Body-Cement Solidified Body" and GB 7023-86 "Long-term radioactive waste solidified body Leaching Test "Carry out various performance tests, see 6 for the results.

Table 6 Comparison of cement solidified body test results

The test results of the solidified body of the comparative example show that at 35% containment capacity, the impact resistance of the low-alkalinity alkali slag cement solidified body is unqualified, and the leaching rate of ²³⁹ Pu(42d) cannot reach <1.0×10 ^-5 m/ d; and although the leaching rate of ¹³⁷ Cs (42d) and ²³⁹ Pu (42d) of alkali slag-clay composite cement meets the national standard requirements, its curing effect is better than the curing effect of the present invention's curing material (referring to table 2, table 3 and Table 5) are much lower, and some are even an order of magnitude higher.

The experiment also verified that using low-alkalinity alkali slag cement AK1 as the base solidification material, to make all the indicators qualified, the maximum containment capacity is only 20%.

The above examples illustrate that the cement-based solidified material of the present invention has the characteristics of large waste holding capacity, stable mechanical properties, and low nuclide ion erosion rate ( ²³⁹ Pu).

The above examples illustrate the preparation of the cement-based solidified material for treating medium and low radioactive incineration ash according to the present invention and the different physical, mechanical and material properties obtained by different component material ratios. According to the characteristics of incineration ash, the present invention adopts different curing substrates and corresponding processes, improves the compatibility between incineration ash and modified cement, and increases the waste capacity of about 20% to 30% to 40%. It greatly reduces the volume increase in the curing process, reduces the space and cost of later disposal, and has a major economic effect. All in all, the cement-based solidified material of the present invention has the characteristics of large waste storage capacity, stable mechanical properties, and low nuclide ion erosion rate ( ²³⁹ Pu), and its preparation process has no chemical pollution sources, no radioactivity, no light pollution, and no noise. The development and utilization of the cement-based solidified material of the invention has huge market potential, broad market space and prospects. From the perspective of environmental protection and sustainable development, the development of this multifunctional composite material has very important economic, environmental and social significance.

Claims (8)

1. A cement-based solidified material for processing medium and low radioactive incineration ash. The material to be excited is composed of ground slag, fly ash, zeolite, metakaolin and cement clinker, mixed evenly with the activator, and cured 1. The modified cement obtained by solidification; the ratio of parts by weight of the slag, fly ash, zeolite, metakaolin and cement clinker is 40-70:10-20:10-30:10-35:4-20. 2. The cement-based solidified material according to claim 1, characterized in that: the slag, fly ash, zeolite, metakaolin and cement clinker are respectively ground to 400～500±20m ² /Kg, 400～ 500±20m ² /Kg, 100~300 mesh, 1000~1500 mesh, 400~500±20m ² /Kg powder. 3. A cement-based solidified material for processing medium and low radioactive incineration ash. The material to be excited is composed of ground slag, fly ash, zeolite, metakaolin and cement clinker, and is mixed with an activator evenly. After curing , the modified cement obtained by curing; the ratio of parts by weight of the slag, fly ash, zeolite, metakaolin and cement clinker is 40～70: 10～20: 10～30: 10～35: 4～20; The slag, fly ash, zeolite, metakaolin and cement clinker are respectively ground to 400-500±20m ² /Kg, 400-500±20m ² /Kg, 100-300 mesh, 1000-1500 mesh, 400 ~500±20m ² /Kg powder; The cement-based solidified material is also added with polymer latex powder, and the amount of the polymer latex powder is included in the weight of the cement-based solidified material powder, and 100 parts by weight of the cement-based solidified material powder contains 4 to 6 parts by weight of Polymer latex powder. 4. A cement-based solidified material for processing medium and low radioactive incineration ash. The material to be activated is composed of ground slag, fly ash, zeolite, metakaolin and cement clinker, and is mixed with an activator evenly. After curing , the modified cement obtained by curing; the weight and number ratio of the slag, fly ash, zeolite, metakaolin and cement clinker is 40～70: 10～20: 10～30: 10～35: 4～20; The slag, fly ash, zeolite, metakaolin and cement clinker are respectively ground to 400-500±20m ² /Kg, 400-500±20m ² /Kg, 100-300 mesh, 1000-1500 mesh, 400 ~500±20m ² /Kg powder; Polymer latex powder is also added to the cement-based solidified material, and the amount of the polymer latex powder is included in the weight of the cement-based solidified material powder, and 100 parts by weight of the cement-based solidified material powder contains 4 to 6 parts by weight of polymer latex powder; The cement-based solidified material is also added with a Nai series high-efficiency water reducer FDN, and the amount of the water-reduced agent FDN is included in the weight of the cement-based solidified material powder, and 0.3 to 0.8 Nai series high-efficiency water reducer in parts by weight. 5. The cement-based solidified material according to claim 4, characterized in that: the activator is a liquid activator or a composite solid activator; the liquid activator is water glass with n being 1.2 to 1.8, and the addition amount is 5-10% of the weight of cement-based solidified material powder; the composite solid activator is 15-35 parts by weight of sodium silicate, 55-75 parts by weight of sodium sulfate and 5-15 parts by weight of calcium hydroxide Assembled, the dosage of the composite solid activator is included in the weight of the cement-based solidified material powder, and 100 parts by weight of the cement-based solidified material powder contains 5-10 parts by weight of the solid activator. 6. A method for processing medium and low radioactive incineration ash, characterized in that: using the cement-based solidified material according to claim 4 or 5, the material to be excited, polymer latex powder and Nai series water reducer FDN and the activator Mixing, according to the inclusion capacity of 30-40%, mixing with incineration ash according to the curing operation, stirring and curing until solidified. 7. The method according to claim 6, characterized in that: the material to be excited, the polymer latex powder and the nano-based water reducer FDN are directly mixed with the solid activator, and then mixed with incineration ash for 20 ± 2 minutes and then mixed with water and stirred , Conservation until solidification. 8. The method according to claim 6, characterized in that: the material to be excited, the polymer latex powder and the nano-based water reducer FDN are directly mixed and stirred with the incineration ash and the liquid activator, and then cured until solidified after stirring for 15±2min .

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