Geopolymer, solidified geopolymer, and method for treating radioactive waste

Abstract

14 The present invention provides a geopolymer capable of suppressing the elution of carbonate ions containing C, a solidified geopolymer, and a method for treating radioactive waste. [Solution] 14 A geopolymer comprising an aqueous sodium hydroxide solution containing CO2 gas and a filler containing at least blast furnace slag, wherein the content of the blast furnace slag relative to the total mass (100 mass%) of the filler is 20 mass% or more and 100 mass% or less.

Description

[Technical Field]

[0001] The present invention relates to a geopolymer, a solidified geopolymer, and a method for treating radioactive waste. [Background technology]

[0002] At nuclear power plants, radioactive carbon ( 14 C) generated and generated 14 C is radioactive carbon dioxide ( 14 CO2). 14 Although CO2 is absorbed by concrete, the gaseous substance remains free to move, spreading the contamination over a wider area. 14 It is known that CO2 can penetrate concrete to a depth of several tens of centimeters. 14 Concrete contaminated with CO2 (hereinafter referred to as " 14 The amount of CO2-contaminated concrete (called "CO2-contaminated concrete") will be enormous.

[0003] Becomes radioactive waste 14 When decommissioning aging nuclear power plants, in order to reduce the amount of CO2-contaminated concrete, the contaminated parts are scraped off and then separated into contaminated and non-contaminated parts. The contaminated parts are sealed with cement or geopolymers and disposed of as radioactive waste. The non-contaminated parts are treated as non-radioactive waste. If the radioactive waste is to be buried in the future, it is preferable that the solidified waste be in a state that makes it difficult for radioactive materials to leach into groundwater, etc. There has been no record of geopolymers being used to date.

[0004] 14The use of geopolymers for CO2 fixation is being considered (see, for example, Patent Document 1). Geopolymers are made by mixing industrial waste such as fly ash and blast furnace slag with an alkaline solution such as sodium hydroxide and solidifying the mixture. In general, geopolymers are superior to cement-solidified materials in terms of strength, heat resistance, durability, etc. Geopolymers can be controlled in terms of strength, fluidity, etc. by devising the materials and composition (see, for example, Patent Document 1). Furthermore, by producing geopolymers using a low-concentration alkaline solution, it is possible to suppress the elution of carbonate ions. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-178761 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when geopolymers are produced using low-concentration alkaline solutions, although the leaching of carbonate ions can be suppressed, there is still the problem that some carbonate ions still leach out.

[0007] The present invention has been made in view of the above circumstances, 14 The present invention aims to provide a geopolymer capable of suppressing the elution of carbonate ions containing C, a solidified geopolymer, and a method for treating radioactive waste. [Means for solving the problem]

[0008] The present invention has the following aspects. [1] 14 The present invention comprises an alkaline aqueous solution containing CO2 gas and a filler containing at least blast furnace slag, A geopolymer in which the content of the blast furnace slag relative to the total mass (100% by mass) of the filler is 20% by mass or more and 100% by mass or less. [2] The geopolymer according to [1], wherein the filler comprises fly ash. [3] The geopolymer according to [1] or [2], wherein the concentration of the alkaline aqueous solution is 0.9 mol / L or more and 5.0 mol / L or less. [4] The geopolymer according to any one of [1] to [3], further comprising fine powder of mortar obtained from contaminated concrete. [5] A solidified geopolymer consisting of a hardened geopolymer according to any one of [1] to [4]. [6] 14 A crushing process to crush the contaminated concrete contaminated with CO2; a heating step of heating the crushed contaminated concrete; The contamination was generated by heating the contaminated concrete. 14 CO2 gas is captured using an alkaline solution. 14 a capturing step of forming an alkaline aqueous solution containing CO2 gas; The aforementioned 14 A kneading process of kneading an alkaline aqueous solution containing CO2 gas with a filler containing at least blast furnace slag to form a geopolymer; A solidification step of solidifying the geopolymer, A method for treating radioactive waste, wherein the content of the blast furnace slag relative to the total mass (100% by mass) of the filler is 20% by mass or more and 100% by mass or less. [7] Further, a separation step is provided in which the heated contaminated concrete is separated into coarse aggregate and fine mortar powder, In the kneading step, 14 [6] A method for treating radioactive waste according to [6], wherein an alkaline aqueous solution containing CO2 gas, the fine powder, and a filler containing at least blast furnace slag are kneaded together to form a geopolymer. [Effects of the Invention]

[0009] According to the present invention, 14 It is possible to provide a geopolymer capable of suppressing the elution of carbonate ions containing C, a solidified geopolymer, and a method for treating radioactive waste. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing the relationship between the blending ratio of fly ash and blast furnace slag in a filler and the amount of carbonate ions eluted. DETAILED DESCRIPTION OF THE INVENTION

[0011] Embodiments of the geopolymer, the solidified geopolymer, and the method for treating radioactive waste of the present invention will be described below. It should be noted that the present embodiment is specifically described to allow a better understanding of the gist of the invention, and does not limit the present invention unless otherwise specified.

[0012] [Geopolymer] The geopolymer according to one embodiment of the present invention comprises: 14 It consists of an alkaline aqueous solution containing CO2 gas and a filler containing at least blast furnace slag.

[0013] The blast furnace slag content relative to the total mass (100% by mass) of the filler is 20% by mass or more and 100% by mass or less, preferably 50% by mass or more and 100% by mass or less, and more preferably 75% by mass or more and 100% by mass or less. When the blast furnace slag content is above the lower limit, it hardens as a geopolymer. When the blast furnace slag content is below the upper limit, it is possible to suppress the elution of immobilized CO2 gas.

[0014] The filler may contain fly ash. When the filler contains fly ash, the filler is a composition containing blast furnace slag and fly ash. That is, the components of the filler other than the blast furnace slag are fly ash. When the filler contains fly ash, the content of fly ash relative to the total mass (100 mass%) of the filler is 0% by mass or more and 75% by mass or less, preferably 0% by mass or more and 50% by mass or less, and more preferably 0% by mass or more and 25% by mass or less. When the content of fly ash is equal to or more than the lower limit, elution of the immobilized CO2 gas can be suppressed. When the content of fly ash is equal to or less than the upper limit, material costs can be kept low.

[0015] The filler content relative to the total mass (100% by mass) of the geopolymer is preferably 60% to 75% by mass, more preferably 65% ​​to 75% by mass, and even more preferably 70% to 75% by mass. If the filler content is above the lower limit, the geopolymer will harden. If the filler content is below the upper limit, the material can be kneaded using a general mixer.

[0016] The concentration of the alkaline aqueous solution is preferably 0.9 mol / L to 5 mol / L, more preferably 3 mol / L to 5 mol / L, and even more preferably 4 mol / L to 5 mol / L. If the concentration of the alkaline aqueous solution is above the lower limit, it will harden as a geopolymer. If the concentration of the alkaline aqueous solution is below the upper limit, the material can be kneaded using a general mixer. Here, the concentration of the alkaline aqueous solution refers to the concentration of the alkaline aqueous solution before kneading with the filler.

[0017] The alkaline aqueous solution may be an aqueous solution of an alkali metal hydroxide or an alkaline earth metal hydroxide. Examples of alkali metal hydroxides include sodium hydroxide and potassium hydroxide. Examples of alkaline earth metal hydroxides include calcium hydroxide.

[0018] of the total mass of the geopolymer 14The content of the alkaline aqueous solution containing CO gas is preferably 25% by mass or more and 40% by mass or less, more preferably 25% by mass or more and 35% by mass or less, and even more preferably 25% by mass or more and 30% by mass or less. 14 It is easy to knead the alkaline aqueous solution containing CO2 gas and the filler. If the content of the alkaline aqueous solution is below the upper limit, the geopolymer is easily solidified.

[0019] 14 In alkaline aqueous solution containing CO2 gas 14 The content of CO2 gas is preferably 0 mol / L or more and 1 mol / L or less, more preferably 0 mol / L or more and 0.5 mol / L or less, and even more preferably 0 mol / L or more and 0.1 mol / L or less. 14 When the content of CO2 gas is equal to or greater than the lower limit, 14 It becomes possible to solidify CO2 gas. 14 If the CO2 gas content is below the upper limit, it hardens as a geopolymer.

[0020] The geopolymer of this embodiment may include fine mortar powder obtained from contaminated concrete. The fine mortar powder was obtained by separating contaminated concrete into coarse aggregate and fine mortar powder. The particle size of the fine powder of the mortar is preferably 0.15 mm to 5 mm, more preferably 0.15 mm to 4 mm, and even more preferably 0.15 mm to 3 mm. When the particle size of the fine powder is equal to or greater than the lower limit, not much energy is required when kneading with the alkaline solution and filler, as described below. When the particle size of the fine powder is equal to or less than the upper limit, the fine powder can be sufficiently mixed with the alkaline solution and filler, as described below.

[0021] The content of the mortar fine powder relative to the total mass (100% by mass) of the geopolymer is 0% by mass or more and 70% by mass or less, preferably 0% by mass or more and 60% by mass or less, and more preferably 0% by mass or more and 50% by mass or less. When the content of the mortar fine powder is above the lower limit, 14 This allows for the solidification of CO2-contaminated waste. If the fine powder content of the mortar is below the upper limit, it will harden as a geopolymer.

[0022] As the blast furnace slag, either slowly cooled blast furnace slag or granulated blast furnace slag can be used. As an example of blast furnace slag, for example, blast furnace slag powder for concrete (Blaine value 3000 cm) whose quality standard is specified in JIS A 6206:2013 is used. 2 / g class, 4000cm 2 / g class, 6000cm 2 / g class, 8000cm 2 / g class).

[0023] Fly ash is a type of ash produced when coal is burned. Examples of fly ash include fly ash types I to IV, whose quality standards are defined in JIS A 6201:2015. In addition, in the present invention, fly ash raw powder that does not meet JIS standards and that has not been subjected to any classification treatment or the like may be used, which is obtained from fly ash generated from a coal-fired power plant. The fly ash can be used alone or in combination of two or more types.

[0024] For fine mortar powder 14 The blending ratio of the alkaline aqueous solution containing CO2 gas is preferably 0.07 to 0.4 by mass, more preferably 0.1 to 0.2, and even more preferably 0.1 to 0.15. If the blending ratio is above the lower limit, the materials can be kneaded using a general mixer. If the blending ratio is below the upper limit, the material hardens as a geopolymer.

[0025] For fillers 14 The blending ratio of the alkaline aqueous solution containing CO2 gas is preferably 0.5 to 2, more preferably 0.5 to 1.5, and even more preferably 0.5 to 1. When the blending ratio is equal to or greater than the lower limit, the materials can be kneaded using a general mixer. When the blending ratio is equal to or less than the upper limit, the material hardens as a geopolymer.

[0026] The blending ratio of mortar fine powder to filler, by mass, is preferably not more than 7, more preferably not more than 6, and even more preferably not more than 5. When the blending ratio is not more than the upper limit, the materials can be mixed using a general mixer and harden as a geopolymer.

[0027] [Geopolymer manufacturing method] A method for producing a geopolymer according to one embodiment of the present invention includes: 14 A crushing process for crushing contaminated concrete contaminated with CO2, a heating process for heating the crushed contaminated concrete, and a process for heating the contaminated concrete. 14 CO2 gas is captured using an alkaline solution. 14 a capturing step of forming an alkaline aqueous solution containing CO gas; 14 and a kneading step in which an alkaline aqueous solution containing CO2 gas is kneaded with a filler containing at least blast furnace slag to form a geopolymer.

[0028] Crushing process In the crushing process, radioactive materials generated in the reactor are 14 Crushing contaminated concrete contaminated with CO2. Contaminated concrete is subject to change depending on the operating conditions of the reactor. 14 CO2 has penetrated deep into the interior, and in some places has penetrated to a depth of several tens of millimeters. In decontamination treatment for such contaminated concrete, the surface layer of the contaminated concrete is removed to a thickness of at least several tens of millimeters, and this removed portion is then treated as radioactive waste. The method for crushing the contaminated concrete is not particularly limited, but examples thereof include grinding and removing the surface layer of the contaminated concrete.

[0029] The particle size of the contaminated concrete after crushing is preferably 10 mm or more and 80 mm or less, more preferably 10 mm or more and 60 mm or less, and even more preferably 10 mm or more and 40 mm or less. If the particle size of the contaminated concrete after crushing is equal to or greater than the lower limit, the contaminated concrete can be efficiently separated into coarse aggregate and fine mortar powder in the separation step described below. If the particle size of the contaminated concrete after crushing is equal to or less than the upper limit, the contaminated concrete can be efficiently separated into fine mortar powder in the heating step described below. 14 CO2 gas can be generated.

[0030] "Heating process" In the heating step, the contaminated concrete crushed in the crushing step is heated. The temperature to which the contaminated concrete is heated is preferably 200° C. or higher and 450° C. or lower, more preferably 250° C. or higher and 400° C. or lower, and even more preferably 300° C. or higher and 350° C. or lower. If the temperature to which the contaminated concrete is heated is above the lower limit, a large amount of 14 Heat treatment can be performed without volatilizing CO2. When the temperature to which the contaminated concrete is heated is equal to or lower than the upper limit, the strength of the contaminated concrete decreases due to heating, and the contaminated concrete can be efficiently separated into coarse aggregate and fine mortar powder.

[0031] By heating the contaminated concrete, 14 CO2 gas is produced.

[0032] "Collection process" In the collection process, the contaminated concrete was heated during the heating process. 14 CO2 gas is captured using an alkaline aqueous solution, 14 The alkaline aqueous solution contains CO2 gas. The alkaline aqueous solution can be the same as the geopolymer mentioned above.

[0033] "Separation process" The method for producing a geopolymer of this embodiment may include a separation step of separating the heated contaminated concrete into coarse aggregate and fine mortar powder. In the separation step, the contaminated concrete heated in the heating step is separated into coarse aggregate and fine mortar powder. In order to separate the contaminated concrete into coarse aggregate and fine mortar powder, it is preferable to subject the contaminated concrete to a grinding treatment. 14 It is known that CO2 gas penetrates the mortar portion of concrete, so contamination is observed in the mortar portion, but not in the coarse aggregate. In the separation process, contaminated concrete is separated into coarse aggregate and fine mortar powder, with the coarse aggregate becoming non-radioactive waste and the fine mortar powder becoming radioactive waste. For example, by subjecting contaminated concrete to a grinding process, the contaminated concrete can be separated into coarse aggregate and fine mortar powder, reducing the volume of radioactive waste. In particular, by heating the contaminated concrete, 14 After generating CO2 gas, the contaminated concrete can be ground to reduce the volume of fine mortar powder that becomes radioactive waste.

[0034] The grinding process can be carried out in accordance with the method described in JP 2017-227493 A, for example.

[0035] The particle size of the fine powder of mortar obtained by the grinding treatment is preferably 0.15 mm or more and 5 mm or less, more preferably 0.15 mm or more and 4 mm or less, and even more preferably 0.15 mm or more and 3 mm or less. 14 When the particle size of the fine powder is equal to or less than the upper limit, the fine powder can be kneaded with the alkaline aqueous solution containing CO2 gas, fly ash, and blast furnace slag without requiring much energy. 14 When kneading with the alkaline aqueous solution containing CO2 gas, fly ash, and blast furnace slag, these raw materials can be thoroughly mixed with the fine powder.

[0036] The coarse aggregate obtained in the separation process becomes non-radioactive waste. The non-radioactive waste coarse aggregate is reused.

[0037] "Mixing process" In the kneading process, 14 A geopolymer is obtained by kneading an alkaline aqueous solution containing CO2 gas with a filler containing at least blast furnace slag. In addition, when the method for producing a geopolymer of this embodiment has the above separation step, in the kneading step, 14 An alkaline aqueous solution containing CO2 gas, the above fine powder, and a filler containing at least blast furnace slag are kneaded to form a geopolymer. 14 The method for kneading the alkaline aqueous solution containing CO2 gas, the fine powder, and the filler containing at least blast furnace slag is not particularly limited, but it is preferable to, for example, put the raw materials into a container such as a mortar and knead them using a stirring device such as a twin-screw mixer. Note that, from the viewpoint of safety, the fine powder, which is radioactive waste, should not be mixed with other raw materials ( 14 It is preferable to mix the alkaline aqueous solution containing CO2 gas and the filler to form a paste before adding it.

[0038] 14 The compounding ratio of the alkaline aqueous solution containing CO2 gas (hereinafter referred to as "A1 component"), the filler (hereinafter referred to as "B1 component"), and the fine powder (hereinafter referred to as "C1 component") is not particularly limited, but for example, the range shown below is preferable. The blending ratio of B1 component to A1 component + C1 component (B1 component / (A1 component + C1 component)) is preferably 0.1 to 0.2 in mass ratio, more preferably 0.1 to 0.175 in mass ratio, and even more preferably 0.1 to 0.15 in mass ratio. When the blending ratio (B1 component / (A1 component + C1 component)) is equal to or greater than the lower limit, the geopolymer solidifies. When the blending ratio (B1 component / (A1 component + C1 component)) is equal to or less than the upper limit, the mixture can be kneaded to produce a waste product.

[0039] The blending ratio of the C1 component to the A1 component and the B1 component (C1 component / (A1 component+B1 component)) is preferably 1.5 or more and 5 or less, more preferably 1.5 or more and 4 or less, and even more preferably 1.5 or more and 3 or less, by mass. When the blending ratio (C1 component / (A1 component+B1 component)) is equal to or more than the lower limit, the waste blend is efficient when it is made into a waste form. When the blending ratio (C1 component / (A1 component+B1 component)) is equal to or less than the upper limit, the waste form can be produced by kneading.

[0040] The blast furnace slag content relative to the total mass (100% by mass) of the filler is 20% by mass or more and 100% by mass or less, preferably 50% by mass or more and 100% by mass or less, and more preferably 75% by mass or more and 100% by mass or less. When the blast furnace slag content is above the lower limit, it hardens as a geopolymer. When the blast furnace slag content is below the upper limit, it is possible to suppress the elution of immobilized CO2 gas.

[0041] When the filler contains fly ash, the content of fly ash relative to the total mass (100 mass%) of the filler is 0% by mass or more and 75% by mass or less, preferably 0% by mass or more and 50% by mass or less, and more preferably 0% by mass or more and 25% by mass or less. When the content of fly ash is equal to or more than the lower limit, elution of the immobilized CO2 gas can be suppressed. When the content of fly ash is equal to or less than the upper limit, material costs can be kept low.

[0042] According to the geopolymer of this embodiment, by setting the content of blast furnace slag to 20% by mass or more and 100% by mass or less with respect to the total mass (100% by mass) of the filler, 14 It is possible to suppress the elution of carbonate ions containing C. It is also possible to suppress the elution of carbonate ions that are generated by heating contaminated concrete. 14 An alkaline aqueous solution containing CO2 gas, fine mortar powder obtained by separating heated contaminated concrete, and a filler containing at least blast furnace slag are mixed together to form a geopolymer, which is then solidified into radioactive waste, allowing for efficient and appropriate disposal of radioactive waste.

[0043] [Solidified geopolymer] A solidified geopolymer according to one embodiment of the present invention comprises the hardened geopolymer of the above-described embodiment. That is, the solidified geopolymer according to this embodiment includes an alkali carbonate and a filler containing at least blast furnace slag. The solidified geopolymer according to this embodiment may also include fine powder of mortar obtained from contaminated concrete. The solidified geopolymer of this embodiment can be obtained by the radioactive waste treatment method of the embodiment described below.

[0044] In the solidified geopolymer of this embodiment, the compounding ratio of the alkali carbonate (hereinafter referred to as "component A2"), filler (hereinafter referred to as "component B2"), and fine powder (hereinafter referred to as "component C2") is not particularly limited, but for example, the range shown below is preferable. Alkali carbonate is dissolved in the above alkaline solution. 14 It is made up of CO2 gases combined together.

[0045] The blending ratio of B2 component to A2 component + C2 component (B2 component / (A2 component + C2 component)) is preferably 0.1 to 0.2 in mass ratio, more preferably 0.1 to 0.175 in mass ratio, and even more preferably 0.1 to 0.15 in mass ratio. When the blending ratio (B2 component / (A2 component + C2 component)) is equal to or greater than the lower limit, the geopolymer solidifies. When the blending ratio (B2 component / (A2 component + C2 component)) is equal to or less than the upper limit, the mixture can be kneaded to produce a waste product.

[0046] The blending ratio of C2 component to A2 component + B2 component (C2 component / (A2 component + B2 component)) is preferably 1.5 to 5 in mass ratio, more preferably 1.5 to 4 in mass ratio, and even more preferably 1.5 to 3 in mass ratio. When the blending ratio (C2 component / (A2 component + B2 component)) is equal to or greater than the lower limit, the waste blend is efficient when it is made into waste form. When the blending ratio (C2 component / (A2 component + B2 component)) is equal to or less than the upper limit, the waste form can be produced by kneading.

[0047] The content of blast furnace slag relative to the total mass (100% by mass) of component B2 is 20% by mass or more and 100% by mass or less, preferably 50% by mass or more and 100% by mass or less, and more preferably 75% by mass or more and 100% by mass or less. When the content of blast furnace slag is above the lower limit, it hardens as a geopolymer. When the content of blast furnace slag is below the upper limit, it is possible to suppress the elution of immobilized CO2 gas.

[0048] According to the solidified geopolymer of this embodiment, it is made of the hardened geopolymer of the above embodiment, and the content of blast furnace slag relative to the total mass (100 mass%) of the filler is 20 mass% or more and 100 mass% or less, so it is more effective than conventional solidified geopolymers. 14 It is possible to suppress the elution of carbonate ions containing C. Furthermore, since all components of the solidified geopolymer of this embodiment are waste, it can be safely and appropriately disposed of as radioactive waste in a final disposal site without using any materials other than waste.

[0049] [Radioactive waste disposal methods] A method for treating radioactive waste according to one embodiment of the present invention includes a step of obtaining a geopolymer by the method for producing a geopolymer according to the above-described embodiment, and a step of solidifying the geopolymer. That is, the method for treating radioactive waste according to one embodiment of the present invention includes the steps of: 14 A crushing process for crushing contaminated concrete contaminated with CO2, a heating process for heating the crushed contaminated concrete, and a process for heating the contaminated concrete. 14 CO2 gas is captured with a sodium hydroxide solution, 14 a capturing step of forming a sodium hydroxide aqueous solution containing CO2 gas; 14 The method includes a kneading step in which a sodium hydroxide aqueous solution containing CO2 gas is kneaded with a filler containing at least blast furnace slag to form a geopolymer, and a solidification step in which the geopolymer is solidified.

[0050] "Solidification process" In the solidification process, the geopolymer obtained in the kneading process is solidified.

[0051] A geopolymer containing an alkaline solution and a filler containing at least blast furnace slag is poured into a formwork and left to solidify for, for example, 1 to 14 days, resulting in a solidified geopolymer.

[0052] The solidified geopolymer will be sent to a final disposal site and disposed of as radioactive waste.

[0053] According to the method for treating radioactive waste of this embodiment, the content of blast furnace slag relative to the total mass (100 mass%) of the filler is set to 20 mass% or more and 100 mass% or less, so that the radioactive waste treatment can be carried out more efficiently than in the past. 14 It is possible to suppress the elution of carbonate ions containing C. It is also possible to suppress the elution of carbonate ions that are generated by heating contaminated concrete. 14 An alkaline aqueous solution containing CO2 gas, fly ash, and blast furnace slag are mixed to form a geopolymer, which is then solidified to form radioactive waste, allowing for efficient and appropriate radioactive waste disposal. In other words, since all of the components used in the radioactive waste of this embodiment are waste, the waste can be effectively utilized to solidify the radioactive waste. [Example]

[0054] The present invention will be explained in more detail below by way of experimental examples, but the present invention is not limited to the following experimental examples.

[0055] [Experimental Example] "Geopolymer production" Fly ash, blast furnace slag, and aqueous sodium hydroxide solution were mixed in a twin-screw mixer to obtain a mixture. Here, the mass ratios of fly ash, blast furnace slag, and aqueous sodium hydroxide solution were set to 100:0:50, 75:25:50, 50:50:50, 25:75:50, and 0:100:50. The sodium hydroxide solution used had a concentration of 1 mol / L, which gave the lowest carbonate ion elution rate. To the above kneaded product, 14A geopolymer containing sodium hydroxide solution was prepared by adding 2% by mass of sodium carbonate as a CO2 simulant. The resulting geopolymer was subjected to a carbonate ion elution test in accordance with JIS K 0058-1. The results are shown in Figure 1. The results shown in Figure 1 indicate that the amount of carbonate ions eluted decreases (the elution of carbonate ions is suppressed) as the blending ratio of blast furnace slag increases. The compositions of fly ash and blast furnace slag are shown in Table 1.

[0056] [Table 1]

Claims

1. １４ CO ２ a gas-containing alkaline aqueous solution and a filler containing at least blast furnace slag; The content of the blast furnace slag relative to the total mass (100% by mass) of the filler is 20% by mass or more and 100% by mass or less.

2. 10. The geopolymer of claim 1, wherein the filler comprises fly ash.

3. The geopolymer according to claim 1, wherein the concentration of the alkaline aqueous solution is 0.9 mol / L or more and 5.0 mol / L or less.

4. 10. The geopolymer of claim 1, further comprising fine powder of mortar obtained from contaminated concrete.

5. A solidified geopolymer comprising a hardened geopolymer according to any one of claims 1 to 4.

6. １４ CO ２ a crushing step of crushing the contaminated concrete; a heating step of heating the crushed contaminated concrete; The contamination was generated by heating the contaminated concrete. １４ CO ２ The gas is captured with an alkaline aqueous solution, １４ CO ２ a capturing step of forming an alkaline aqueous solution containing the gas; The aforementioned １４ CO ２ A kneading step of kneading an alkaline aqueous solution containing a gas with a filler containing at least blast furnace slag to form a geopolymer; A solidification step of solidifying the geopolymer, A method for treating radioactive waste, wherein the content of the blast furnace slag relative to the total mass (100% by mass) of the filler is 20% by mass or more and 100% by mass or less.

7. The method further includes a separation step of separating the heated contaminated concrete into coarse aggregate and fine mortar powder, In the kneading step, １４ CO ２ The radioactive waste treatment method according to claim 6, wherein an alkaline aqueous solution containing a gas, the fine powder, and a filler containing at least blast furnace slag are kneaded to form a geopolymer.

Images