Method for embedding in a space and embedding system

Abstract

To provide a method and system for filling a space by injecting a slurry of a specific composition into the space and reacting it with carbon dioxide.SOLUTION: Disclosed is a method of filling a space including: preparing a composition containing a hydraulic material and at least one selected from the group consisting of an alkali stimulator, a dispersant, and a hardening inhibitor; and injecting a slurry containing the composition into the space and reacting the slurry with carbon dioxide injected into the space together with the slurry or with carbon dioxide that has been injected into the space separately from the slurry. The space may include at least one selected from the group consisting of a pore in a stratum, an underground tunnel, and a coal mining site. The hydraulic material may include an aluminosilicate material. The aluminosilicate material may include a blast furnace slag. The alkali stimulant may include sodium hydroxide.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for embedding in a space and an embedding system. More specifically, the present invention relates to a method and an embedding system for embedding a space by injecting a slurry of a specific composition into the space and reacting it with carbon dioxide.

Background Art

[0002] Greenhouse gases such as carbon dioxide are considered to be the cause of global warming, and the reduction of their emissions is being promoted in each country. Therefore, the development of technologies for immobilizing carbon dioxide, which is a greenhouse gas, as a constituent component of a mineral structure (referred to as "mineralization of carbon dioxide" or "mineral carbonation") has been promoted mainly in developed countries including Japan. Minerals used for the mineralization of carbon dioxide range from natural rocks and silicate minerals such as basalt, olivine, serpentine, and wollastonite, and the research has spread to various types of industrial by-products or wastes.

[0003] Examples of industrial by-products or wastes that are minerals used for the mineralization of carbon dioxide include waste cement, waste concrete, and blast furnace slag that is generated from components other than iron contained in iron ore used in the steelmaking industry and contains a large amount of CaO. For example, Patent Document 1 discloses a carbon dioxide immobilization method in which carbon dioxide is supplied to an aqueous solution in which granulated blast furnace slag, which is a specific type of blast furnace slag, and an alkali are mixed, and the supplied carbon dioxide is reacted with calcium eluted from the slag to produce CaCO3 (calcium carbonate). Patent Document 2 also discloses a carbon dioxide immobilization method including adding NaOH to a mixture of pulverized blast furnace slag and water at a predetermined ratio to decompose the blast furnace slag and subjecting this to a hydrothermal reaction with carbon dioxide.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] For example, in a closed coal mine, the spaces to be filled, such as pores and underground cavities in the strata, are often deformed, flooded, etc., and the space to be filled is partially narrowed or complicated. Therefore, in order to fill the entire space with the filling material up to every corner for such a partially narrowed and complicated space, it is necessary that the fluidity of the filling material is sufficiently high, and the solidification time is controlled and delayed to suppress solidification near the injection port in the space to be filled, and at the same time, it preferably has a solidification performance such that solidification proceeds when the filling material spreads over the entire space.

[0006] An object of the present invention is to provide a method and a system that can efficiently fill a space with a solidifying material having appropriate fluidity and solidifying characteristics, react it with carbon dioxide, which is a greenhouse gas, to solidify it, and embed the space. [Means for Solving the Problems]

[0007] As a result of intensive research, the present inventors have found that by using a composition containing specific components as the solidifying material, slurrying it, injecting it under pressure, and reacting it with carbon dioxide to embed it in the space, it is possible to efficiently fill and solidify the space, and thus completed the present invention.

[0008] That is, one aspect of the present invention for achieving the above object is as follows. A method for embedding a space, comprising: preparing a composition containing a hydraulic material and at least one selected from the group consisting of an alkali stimulant, a dispersant, and a hardening inhibitor; and A method comprising injecting a slurry containing the composition into a space and reacting the carbon dioxide injected into the space together with the slurry or the carbon dioxide injected into the space separately from the slurry to embed the space.

[0009] Another aspect of the present invention for achieving the above object is as follows. A space embedding system, A slurry preparation unit that prepares a slurry using a composition containing a hydraulic material and at least one selected from the group consisting of an alkali stimulant, a dispersant, and a hardening inhibitor, A slurry injection unit that injects the slurry, or the slurry and carbon dioxide, into a space, A system including a carbon dioxide injection unit that separately injects carbon dioxide into the space when the slurry injection unit is a slurry injection unit that injects the slurry into the space without carbon dioxide.

Advantages of the Invention

[0010] According to the method (or system) for embedding a space according to the present invention, a slurry of a composition, which is a solidified substance having appropriate fluidity and solidification characteristics, is injected into the space and reacted with carbon dioxide, which is a greenhouse gas, so that spaces of various shapes can be efficiently filled and solidified to embed the space.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0012] Hereinafter, embodiments for carrying out the present invention will be described. The present invention is not limited by the descriptions of the following embodiments. Since the space embedding system according to the present invention substantially corresponds to a system for realizing the method for embedding the space according to the present invention, hereinafter, embodiments of the embedding method will be mainly described.

[0013] Method for embedding space The method for embedding a space according to the present invention includes preparing a composition containing a hydraulic material and at least one selected from the group consisting of an alkali stimulant, a dispersant, and a curing inhibitor. In a preferred embodiment, the method includes preparing a composition containing a hydraulic material and an alkali stimulant, and optionally containing at least one selected from the group consisting of a dispersant and a curing inhibitor. In another embodiment, the method includes preparing a composition containing a hydraulic material and an alkali stimulant, and optionally containing at least one selected from the group consisting of a dispersant, a curing inhibitor, and a chelating agent (metal eluent). In still another further embodiment, the method includes preparing a composition containing a hydraulic material, and optionally containing at least one selected from the group consisting of an alkali stimulant, a dispersant, a curing inhibitor, and a chelating agent (metal eluent). Note that the constituent components of the composition used in the present method are not limited to those described herein, and may include any other components as long as the desired properties are not impaired.

[0014] Hydraulic material In one embodiment, the hydraulic material, which is one component of the composition used in the method for embedding a space according to the present invention, is not particularly limited as long as it can react with water under a predetermined pH to release and discharge metal ions, and can fix (mineralize) carbon dioxide as a mineral by curing together with these metal ions. Examples include steel slags such as blast furnace slag and steelmaking slag, fly ash, copper slag, Portland cement, blended cement, alumina cement, blast furnace cement, and the like. The hydraulic material is also referred to as a "binder" from the perspective of its function. Among these hydraulic materials, materials containing aluminosilicates such as blast furnace slag and fly ash, or mixtures thereof, are preferred from the perspective of stably mineralizing and fixing carbon dioxide. Among the aluminosilicate-containing materials, blast furnace slag is more preferred. A single type or a mixture of multiple types of these hydraulic materials can be used.

[0015] Blast furnace slag is obtained by reducing and melting iron ore with coke in a blast furnace, which is a smelting furnace for producing pig iron. Components other than iron contained in the iron ore, mainly the ash in the auxiliary materials such as limestone and coke, are melted and recovered together. Blast furnace slag includes those called slowly cooled slag obtained by slowly cooling the melt and those called granulated slag obtained by rapidly cooling. Slowly cooled slag is crystalline and rock-like, while granulated slag is glassy and finely granular. Blast furnace slag has CaO (calcium oxide: quicklime), SiO2 (silica), and Al2O3 (alumina) as main components. Usually, the content of CaO is about 40 - 45% by mass, and the mass ratio of SiO2 can be about 30 - 35% by mass. The fine powder of blast furnace slag forms a stable hydrate in the presence of an alkaline aqueous solution and gives the function of densifying the hardened body structure.

[0016] In a preferred embodiment, the blast furnace slag may be finely pulverized prior to mixing with water to form a slurry. For example, it is preferable to pulverize the blast furnace slag to a degree of 100 mesh or more and 600 mesh or less, and it is more preferable to pulverize it to a degree of 200 mesh or more and 600 mesh or less. By using the blast furnace slag thus finely pulverized, the efficiency of the reaction of the slurry with carbon dioxide (i.e., the carbonation reaction) can be increased.

[0017] Fly ash is formed by spherical fine particles of molten fine coal ash generated by the combustion of coal in a boiler floating in high-temperature combustion gas and then becoming spherical fine particles as the temperature decreases at the boiler outlet. Fly ash can usually be collected at the boiler outlet by an electrostatic precipitator or the like. The main components of fly ash (usually about 70 to 80% by mass) are SiO2 (silica) and Al2O3 (alumina), and the main constituent phases are a glass phase (amorphous Al-Si), crystalline silica (quartz), and crystalline aluminosilicate (3Al2O3·2SiO2: mullite). In addition to SiO2 and Al2O3, fly ash may contain ferric oxide (Fe2O3), calcium oxide (CaO), magnesium oxide (MgO), magnetite (Fe3O4), etc. Among the above constituent phases, the glass phase has pozzolanic reactivity with alkaline substances such as calcium hydroxide. That is, the glass phase of fly ash, for example, in the coexistence with calcium hydroxide generated by the hydration of cement or the like, reacts gently with it to generate calcium silicate hydrate and calcium aluminate hydrate, and gives a function of enhancing the durability and water tightness of the cured product (immobilization and mineralization of carbon dioxide). Fly ash may mainly have a particle size of about 0.1 to 300 μm. Fly ash may contain trace amounts of heavy metals such as selenium, fluorine, boron, and arsenic.

[0018] Alkali stimulant In one embodiment, the alkali stimulant that can be selected as one component of the composition used in the method for embedding a space according to the present invention is not particularly limited as long as it can give an alkaline stimulus to the hydraulic material and promote its hydration and hardening. The alkali stimulant also has a function of promoting the pozzolanic reaction of the hydraulic material. Such alkali stimulants are not particularly limited, but examples include calcium hydroxide (slaked lime: Ca(OH)2), sodium hydroxide (NaOH), potassium hydroxide (KOH), sodium carbonate (Na2CO3), potassium carbonate (K2CO3), sodium sulfate (Na2SO4), calcium nitrite (Ca(NO2)2), aluminum sulfate (Al2(SO4)3), various gypsums (anhydrous gypsum: calcium sulfate (CaSO4), its dihydrate, hemihydrate), various cements, lime dust, sodium silicate (water glass: Na2O·SiO2), etc. Among these alkali stimulants, from the viewpoint of the functionality of promoting the hydration and hardening of the hydraulic material, calcium hydroxide, sodium hydroxide, and sodium silicate are preferable. From the viewpoint of easy availability and cost, sodium hydroxide is more preferable. A single kind or a mixture of two or more kinds of these alkali stimulants can be used.

[0019] Sodium silicate (water glass: Na2O·SiO2) can cause a gelation and plasticization reaction by coexisting during the hardening reaction with carbon dioxide of a hydraulic material (for example, blast furnace slag), and subsequently promote the hardening of the hydraulic material, resulting in an early increase in strength and even an increase in the strength of the final hardened product. The nature of the hydration reaction between sodium silicate (water glass) and the hydraulic material can be determined by the molar ratio SiO2 / Na2O of the SiO2 component and the Na2O component in sodium silicate. The mass ratios of the components including the SiO2 component and the Na2O component in sodium silicate are standardized in JIS K1408-1966. For "No. 1", it is SiO2 35-38% by mass: Na2O 17-19% by mass; for "No. 2", it is SiO2 34-36% by mass: Na2O 14-15% by mass; for "No. 3", it is SiO2 28-30% by mass: Na2O 9-10% by mass; for "sodium metasilicate type 1", it is SiO2 27.5-29% by mass: Na2O 28.5-30% by mass; and for "sodium metasilicate type 2", it is SiO2 19-22% by mass: Na2O 20-22% by mass.

[0020] The blending amount of the alkali stimulant in the above composition (when used) is not particularly limited. From the viewpoints of sufficiently promoting the hydration and hardening of the hydraulic material and the balance between these desired effects and efficiency and economy, for example, it may be 0.05 parts by mass or more and 5 parts by mass or less, preferably 0.05 parts by mass or more and 4 parts by mass or less, 0.05 parts by mass or more and 3 parts by mass or less, 0.05 parts by mass or more and 2 parts by mass or less, 0.05 parts by mass or more and 1 part by mass or less, 0.05 parts by mass or more and 0.8 parts by mass or less, 0.07 parts by mass or more and 5 parts by mass or less, 0.07 parts by mass or more and 4 parts by mass or less, 0.07 parts by mass or more and 3 parts by mass or less, 0.07 parts by mass or more and 2 parts by mass or less, 0.07 parts by mass or more and 1 part by mass or less, 0.07 parts by mass or more and 0.8 parts by mass or less, 0.1 parts by mass or more and 5 parts by mass or less, 0.1 parts by mass or more and 4 parts by mass or less, 0.1 parts by mass or more and 3 parts by mass or less, 0.1 parts by mass or more and 2 parts by mass or less, 0.1 parts by mass or more and 1 part by mass or less, or 0.1 parts by mass or more and 0.8 parts by mass or less per 100 parts by mass of the hydraulic material.

[0021] Other optional components Dispersant In one embodiment of the method for in-situ embedding according to the present invention, the dispersant that can be selected as one component of the composition is not particularly limited as long as it functions to well disperse the hydraulic material, which is an inorganic substance, in the slurry. Here, the good dispersion state in the slurry refers to, for example, a state in which particles of the hydraulic material with an average particle size of about 500 nm to 500 μm are floating and suspended in the aqueous medium without precipitation. By maintaining a good dispersion state of the hydraulic material in the slurry, it is easy to obtain uniform fluidity of the slurry.

[0022] The dispersant that can be used is not particularly limited, and examples thereof include polymer-type dispersants, surfactant-type dispersants, inorganic dispersants, and the like. Examples of the polymer-type dispersant include anionic polymer-type dispersants such as sulfonic acid-based polymers having a sulfonic acid group in the molecule, polycarboxylic acid-based polymers having a carboxyl group in the molecule, particularly polycarboxylic acid ether-based polymers having a carboxyl group and a polyoxyalkylene chain in the molecule, and phosphoric acid-based polymers having a phosphate group in the molecule; cationic polymer-type dispersants such as polyalkylene polyamine-based polymers; and nonionic polymer-type dispersants such as polyethylene glycol and polyether-based polymers.

[0023] The sulfonic acid-based polymer may be any compound having a sulfonic acid group or a group of a salt of sulfonic acid in the molecule. The compound having a sulfonic acid group or a group of a salt of sulfonic acid preferably has an aromatic ring in the molecule. Examples of the sulfonic acid-based polymer include polyalkylaryl sulfonate-based polymers such as naphthalene sulfonic acid formaldehyde condensate, methylnaphthalene sulfonic acid formaldehyde condensate, and anthracene sulfonic acid formaldehyde condensate; melamine formalin resin sulfonate-based polymers such as melamine sulfonic acid formaldehyde condensate; aromatic aminosulfonate-based polymers such as aminoaryl sulfonic acid-phenol-formaldehyde condensate; lignin sulfonate-based water reducing agents such as lignin sulfonate and modified lignin sulfonate; and polystyrene sulfonate-based polymers.

[0024] As the above polycarboxylic acid polymer, a polymer obtained by polymerizing an unsaturated carboxylic acid monomer is preferable. When the composition does not contain an alkali stimulant, among the polycarboxylic acid polymers, a polycarboxylic acid ether polymer obtained by copolymerizing a monomer component containing an unsaturated carboxylic acid monomer and a (poly)alkylene glycol monomer is preferable. The unsaturated carboxylic acid monomer is not particularly limited as long as it has a carboxyl group and an ethylenically unsaturated hydrocarbon group, and examples include unsaturated monocarboxylic acid monomers and unsaturated dicarboxylic acid monomers. Specific examples of the unsaturated monocarboxylic acid monomer include (meth)acrylic acid, crotonic acid, etc., and their monovalent metal salts, divalent metal salts, ammonium salts, organic ammonium salts, etc.; half esters of unsaturated dicarboxylic acid monomers and alcohols having 1 to 22 carbon atoms or glycols having 2 to 4 carbon atoms; half amides of unsaturated dicarboxylic acid monomers and amines having 1 to 22 carbon atoms, etc. Examples of the alcohol having 1 to 22 carbon atoms include methanol, ethanol, propanol, butanol, hexanol, octanol, etc. Examples of the glycol having 2 to 4 carbon atoms include ethylene glycol, propylene glycol, diethylene glycol, etc. Examples of the amine having 1 to 22 carbon atoms include methylamine, ethylamine, propylamine, butylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, octylamine, dodecylamine, etc. Specific examples of the unsaturated dicarboxylic acid monomer include maleic acid, itaconic acid, mesaconic acid, citraconic acid, fumaric acid, etc., and their monovalent metal salts, divalent metal salts, ammonium salts, organic ammonium salts, etc., and their anhydrides. As the above unsaturated carboxylic acid monomer, (meth)acrylic acid (salt), maleic acid (salt) or maleic anhydride is preferable. The (poly)alkylene glycol monomer is not particularly limited as long as it has a (poly)alkylene glycol group and an ethylenically unsaturated hydrocarbon group. (Poly)alkylene glycol groups are preferably oxyalkylene groups having 2 to 18 carbon atoms or polyoxyalkylene groups having an average addition mole number of more than 1, which are adducts of one or more of the above oxyalkylene groups. The number of carbon atoms of the oxyalkylene group is preferably 2 to 12, more preferably 2 to 8, and still more preferably 2 to 4. The oxyalkylene group is an alkylene oxide adduct, and examples of such alkylene oxides include alkylene oxides having 2 to 8 carbon atoms such as ethylene oxide, propylene oxide, butylene oxide, and styrene oxide. More preferably, they are alkylene oxides having 2 to 4 carbon atoms such as ethylene oxide, propylene oxide, and butylene oxide, and still more preferably, they are ethylene oxide and propylene oxide. When the polyalkylene glycol is an adduct of any two or more alkylene oxides selected from ethylene oxide, propylene oxide, butylene oxide, styrene oxide, etc., it may be in any form such as random addition, block addition, or alternating addition. The average addition mole number of the oxyalkylene groups forming the (poly)alkylene glycol group is preferably 1 to 300, more preferably 2 to 200, and still more preferably 2 to 150. The ethylenically unsaturated hydrocarbon group is not particularly limited, but an alkenyl group having 2 to 8 carbon atoms, a (meth)acryloyl group, etc. are preferable.

[0025] As the (poly)alkylene glycol monomer, a compound represented by the following formula (1) is preferable.

Chemical formula

[0026] Specific examples of the above (poly)alkylene glycol-based monomer include polyalkylene glycol (meth)acrylates such as polyethylene glycol (meth)acrylate, and alkoxypolyalkylene glycol (meth)acrylates in which the terminals thereof are hydrophobically modified with a hydrocarbon group having 1 to 30 carbon atoms; compounds obtained by adding 1 to 300 moles of alkylene oxide to unsaturated alcohols having 2 to 8 carbon atoms such as vinyl alcohol, allyl alcohol, methallyl alcohol, 3-methyl-3-buten-1-ol, 3-methyl-2-buten-1-ol, 2-methyl-3-buten-1-ol, 2-methyl-2-buten-1-ol, 3-allyloxy-1,2-propanediol, and compounds in which the terminals thereof are hydrophobically modified with a hydrocarbon group having 1 to 30 carbon atoms. As the compounds obtained by adding 1 to 300 moles of alkylene oxide to unsaturated alcohols having 2 to 8 carbon atoms, those obtained by adding alkylene oxide to 4-hydroxybutyl-1-monovinyl ether, (meth)allyl alcohol or 3-methyl-3-buten-1-ol are preferable.

[0027] The above polycarboxylic acid-based polymer and polycarboxylic acid ether-based polymer may be copolymerized with other copolymerizable monomers other than the unsaturated carboxylic acid-based monomer and the (poly)alkylene glycol-based monomer. Specific examples of other copolymerizable monomers include unsaturated sulfonic acids such as 3-(meth)allyloxy-2-hydroxypropanesulfonic acid, 2-(meth)allyloxyethylenesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, p-styrenesulfonic acid, α-methyl-p-styrenesulfonic acid, vinylsulfonic acid, vinylsulfamic acid, (meth)allylsulfonic acid, isoprenesulfonic acid, 4-(allyloxy)benzenesulfonic acid, 1-methyl-2-propene-1-sulfonic acid, 1,1-dimethyl-2-propene-1-sulfonic acid, 3-butene-1-sulfonic acid, 1-butene-3-sulfonic acid, 2-acrylamido-1-methylpropanesulfonic acid, 2-acrylamidopropanesulfonic acid, 2-acrylamido-n-butanesulfonic acid, 2-acrylamido-2-phenylpropanesulfonic acid, 2-((meth)acryloyloxy)ethanesulfonic acid, and salts thereof; hydroxyl group-containing ethers such as 3-(meth)allyloxy-1,2-dihydroxypropane and 1-allyloxy-3-butoxypropan-2-ol; N-vinyl lactam-based monomers such as N-vinylpyrrolidone; (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, iso-nonyl (meth)acrylate, dodecyl (meth)acrylate, and stearyl (meth)acrylate; hydroxyl group-containing (meth)acrylic acid esters such as hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxy-1-methylethyl (meth)acrylate, 2-hydroxybutyl acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and hydroxypentyl (meth)acrylate; N-substituted or unsubstituted (meth)acrylamides such as (meth)acrylamide, N-monomethyl (meth)acrylamide, N-monoethyl (meth)acrylamide, and N,N-dimethyl (meth)acrylamide;Vinyl aryl monomers such as styrene, α-methylstyrene, vinyltoluene, indene, vinylnaphthalene, phenylmaleimide, vinylaniline, etc.; alkenes such as ethylene, propylene, butadiene, isobutylene, octene, etc.; vinyl carboxylates such as vinyl acetate, vinyl propionate, etc.; vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether, etc.; vinyl ethylene carbonate and its derivatives; unsaturated amines such as N,N-dimethylaminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylamide, vinyl pyridine, vinyl imidazole and their salts or quaternized products thereof; vinyl cyanide-based monomers such as acrylonitrile, methacrylonitrile, etc. may be mentioned.;

[0028] Examples of the above phosphoric acid-based polymers include phosphoric acid-based polymers containing a polyalkylene glycol group and phosphoric acid-based condensates.; As the phosphoric acid-based polymer, a polymer obtained by copolymerizing a monomer component containing a (poly)alkylene glycol-based monomer and a phosphoric acid-based monomer is preferable.; Examples of the above phosphoric acid-based monomers include phosphoric acid mono(2-hydroxyethyl) (meth)acrylate, di-{(2-hydroxyethyl)(meth)acrylic acid} phosphate ester, (poly)alkylene glycol mono(meth)acrylate acid phosphate ester, etc.; As the phosphoric acid-based condensate, for example, a condensate of a phosphoric acid ester and an aldehyde compound is suitable. The phosphoric acid ester is not particularly limited as long as it is an esterified product of phosphoric acids (which may be salts) and a hydroxyl group-containing compound, and one kind or two or more kinds can be used. In addition, it may be any of phosphoric acid monoester, phosphoric acid diester, and phosphoric acid triester.;

[0029] Examples of the surfactant-type dispersant include anionic surfactant-type dispersants such as alkyl sulfonic acid-based, cationic surfactant-type dispersants such as quaternary ammonium-based and alkyl polyamine-based, and nonionic surfactant-type dispersants such as higher alcohol alkylene oxide-based and polyhydric alcohol ester-based.; Examples of the inorganic dispersant include anionic inorganic dispersants such as polyphosphate-based (e.g., sodium tripolyphosphate). A single type or a mixture of two or more types of these dispersants can be used.

[0030] When used, the blending amount of the dispersant in the above composition is not particularly limited. However, from the viewpoint of well-dispersing the hydraulic material in the slurry and the balance between this effect and efficiency and economy, for example, it may be 0.01 part by mass or more and 4 parts by mass or less, preferably 0.01 part by mass or more and 3 parts by mass or less, 0.01 part by mass or more and 2 parts by mass or less, 0.01 part by mass or more and 1 part by mass or less, 0.01 part by mass or more and 0.8 part by mass or less, 0.01 part by mass or more and 0.5 part by mass or less, 0.012 part by mass or more and 4 parts by mass or less, 0.012 part by mass or more and 3 parts by mass or less, 0.012 part by mass or more and 2 parts by mass or less, 0.012 part by mass or more and 1 part by mass or less, 0.012 part by mass or more and 0.8 part by mass or less, 0.012 part by mass or more and 0.5 part by mass or less, 0.015 part by mass or more and 4 parts by mass or less, 0.015 part by mass or more and 3 parts by mass or less, 0.015 part by mass or more and 2 parts by mass or less, 0.015 part by mass or more and 1 part by mass or less, 0.015 part by mass or more and 0.8 part by mass or less, or 0.015 part by mass or more and 0.5 part by mass or less with respect to 100 parts by mass of the hydraulic material.

[0031] Setting inhibitor In one embodiment of the space embedding method according to the present invention, the hardening inhibitor that can be selected as one component of the composition has a function of inhibiting and delaying the early hardening reaction between the hydraulic material and carbon dioxide in the slurry. By including the hardening inhibitor in the composition, when injecting the slurry of the composition together with carbon dioxide into the space for embedding, the early hardening until the slurry reaches the entire space is suppressed, and in particular, it becomes easier to efficiently fill and solidify even the corners of the space including at least partially narrowed or complicated shapes.

[0032] The hardening inhibitor is not particularly limited. For example, oxycarboxylic acids such as gluconic acid, glucoheptonic acid, arabonic acid, tartaric acid, malic acid, and citric acid, or salts thereof; keto acids such as pyruvic acid, oxaloacetic acid, α-ketoglutaric acid, acetoacetic acid, acetonedicarboxylic acid, levulinic acid, propionylacetic acid, benzoylacetic acid, or salts thereof; monosaccharides such as glucose, fructose, galactose, sucrose, xylose, apiose, ribose, isomerized sugar, oligosaccharides such as disaccharides and trisaccharides, or oligosaccharides such as dextrin, or polysaccharides such as dextran, sugars such as molasses containing these; sugar alcohols such as sorbitol; polyhydric alcohols such as glycerin; magnesium silicofluoride; boric acids, etc. can be mentioned. A single kind or a mixture of two or more kinds of these hardening inhibitors can be used. The hardening inhibitor preferably contains at least one selected from the group consisting of oxycarboxylic acids or salts thereof, keto acids or salts thereof, sugars, and sugar alcohols. It is more preferable to contain an oxycarboxylic acid or a salt thereof that also acts as a chelating agent (metal eluting agent) described later.

[0033] The blending amount of the hardening inhibitor in the above composition (when used) is not particularly limited. However, from the viewpoint of sufficiently providing the function of inhibiting and delaying the hardening reaction of the hydraulic material in the slurry and not excessively stopping the hardening reaction, for example, it may be 0.04 parts by mass or more and 4 parts by mass or less, preferably 0.04 parts by mass or more and 3 parts by mass or less, 0.04 parts by mass or more and 2 parts by mass or less, 0.04 parts by mass or more and 1 part by mass or less, 0.04 parts by mass or more and 0.8 parts by mass or less, 0.04 parts by mass or more and 0.5 parts by mass or less, 0.06 parts by mass or more and 4 parts by mass or less, 0.06 parts by mass or more and 3 parts by mass or less, 0.06 parts by mass or more and 2 parts by mass or less, 0.06 parts by mass or more and 1 part by mass or less, 0.06 parts by mass or more and 0.8 parts by mass or less, 0.06 parts by mass or more and 0.5 parts by mass or less, 0.07 parts by mass or more and 4 parts by mass or less, 0.07 parts by mass or more and 3 parts by mass or less, 0.07 parts by mass or more and 2 parts by mass or less, 0.07 parts by mass or more and 1 part by mass or less, 0.07 parts by mass or more and 0.8 parts by mass or less, or 0.07 parts by mass or more and 0.5 parts by mass or less with respect to 100 parts by mass of the hydraulic material.

[0034] Chelating agent (metal eluent) In one embodiment of the spatial embedding method according to the present invention, a chelating agent (which can also be referred to as a metal eluting agent) that can be selected as one component of the composition functions to elute metal ions into the slurry by chelating the metal constituting the hydraulic material in the slurry of the composition. By including a chelating agent (metal eluting agent) in the composition, when the slurry of the composition is injected together with carbon dioxide to embed the space, eluting the metal ions constituting the hydraulic material promotes the reaction between the metal and carbon dioxide, and it becomes possible to increase the amount of carbon dioxide immobilized in the embedding of the space.

[0035] The chelating agent (metal eluting agent) is not particularly limited, and examples thereof include ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), hydroxyethyliminodiacetic acid (HIDA), hydroxyethylethylenediaminetriacetic acid (HEDTA), diethylenetriaminepentaacetic acid (DTPA), triethylenetetraminehexaacetic acid (TTHA), 1,3-propanediaminetetraacetic acid (PDTA), dihydroxyethylethylenediaminediacetic acid (DHEDDA), 1,3-diamino-2-hydroxypropane-tetraacetic acid (DPTA-OH), dihydroxyethylglycine (DHEG), glycol ether diamine tetraacetic acid (GEDTA), dicarboxymethylglutamic acid (CMGA), ethylenediamine-N,N'-disuccinic acid (EDDS), 3-hydroxy-2,2'-iminodisuccinic acid (HIDS), and aminocarboxylic acid chelating agents such as metal (sodium, potassium, etc.) salts thereof; hydroxyethylidene diphosphonic acid (HEDP), nitrilotris(methylenephosphonic acid) (NTMP), phosphonobutane tricarboxylic acid (PBTC), ethylenediamine tetra(methylenephosphonic acid) (EDTMP), diethylenetriamine penta(methylenephosphonic acid) (DTPMP), and phosphonic acid chelating agents such as metal (sodium, potassium, etc.) salts thereof; β-diketones such as acetylacetone, benzoylacetone, stearoylacetone, stearoylbenzoylmethane, dibenzoylmethane; oxyphenols such as catechol, pyrogallol; amino alcohols such as diethanolamine, triethanolamine; amino acids such as glycine, alanine; humic acid; tannic acid; condensed phosphates and the like. A single kind or a mixture of plural kinds of these chelating agents can be used. As the chelating agent, aminocarboxylic acid chelating agents and phosphonic acid chelating agents are preferred.

[0036] The blending amount of the chelating agent (metal-eluting agent) in the above composition (when used) is not particularly limited. However, from the viewpoint of sufficiently promoting the elution of metal from the hydraulic material in the slurry and from the viewpoint of the balance between this effect and efficiency / economy, for example, it may be 0.04 parts by mass or more and 4 parts by mass or less, preferably 0.04 parts by mass or more and 3 parts by mass or less, 0.04 parts by mass or more and 2 parts by mass or less, 0.04 parts by mass or more and 1 part by mass or less, 0.04 parts by mass or more and 0.8 part by mass or less, 0.04 parts by mass or more and 0.5 part by mass or less, 0.06 parts by mass or more and 4 parts by mass or less, 0.06 parts by mass or more and 3 parts by mass or less, 0.06 parts by mass or more and 2 parts by mass or less, 0.06 parts by mass or more and 1 part by mass or less, 0.06 parts by mass or more and 0.8 part by mass or less, 0.06 parts by mass or more and 0.5 part by mass or less, 0.07 parts by mass or more and 4 parts by mass or less, 0.07 parts by mass or more and 3 parts by mass or less, 0.07 parts by mass or more and 2 parts by mass or less, 0.07 parts by mass or more and 1 part by mass or less, 0.07 parts by mass or more and 0.8 part by mass or less, or 0.07 parts by mass or more and 0.5 part by mass or less, per 100 parts by mass of the hydraulic material.

[0037] In one embodiment, the water content contained in the slurry of the composition is not particularly limited. However, from the viewpoint of ensuring the fluidity of the slurry for press-fitting into the space and the balance between the effectiveness / efficiency of the curing reaction, it is usually 5 parts by mass or more and 500 parts by mass or less, preferably 5 parts by mass or more and 400 parts by mass or less, 5 parts by mass or more and 300 parts by mass or less, 5 parts by mass or more and 200 parts by mass or less, 5 parts by mass or more and 100 parts by mass or less, 10 parts by mass or more and 500 parts by mass or less, 10 parts by mass or more and 400 parts by mass or less, 10 parts by mass or more and 300 parts by mass or less, 10 parts by mass or more and 200 parts by mass or less, 10 parts by mass or more and 100 parts by mass or less, 20 parts by mass or more and 500 parts by mass or less, 20 parts by mass or more and 400 parts by mass or less, 20 parts by mass or more and 300 parts by mass or less, 20 parts by mass or more and 200 parts by mass or less, 20 parts by mass or more and 100 parts by mass or less, 30 parts by mass or more and 500 parts by mass or less, 30 parts by mass or more and 400 parts by mass or less, 30 parts by mass or more and 300 parts by mass or less, 30 parts by mass or more and 200 parts by mass or less, 30 parts by mass or more and 100 parts by mass or less, 40 parts by mass or more and 500 parts by mass or less, 40 parts by mass or more and 400 parts by mass or less, 40 parts by mass or more and 300 parts by mass or less, 40 parts by mass or more and 200 parts by mass or less, or 40 parts by mass or more and 100 parts by mass or less, per 100 parts by mass of the hydraulic material.

[0038] The slurry of the composition can be obtained by stirring and mixing the above essential hydraulic material and, optionally, the optional components and water at a predetermined ratio. The stirring and mixing can usually be carried out at room temperature, but it may also be carried out, for example, at 5°C or higher and 50°C or lower. Also, the time for stirring and mixing is not particularly limited, but it may be 10 seconds or longer and 1 hour or shorter, and typically can be 20 seconds or longer and 40 minutes or shorter.

[0039] Geopolymer In one embodiment, in the coexistence state of sodium silicate (water glass), an aluminosilicate material (active filler) such as blast furnace slag or fly ash as a hydraulic material, water, and, optionally, other alkali stimulants such as sodium hydroxide (NaOH) are mixed to form a geopolimer slurry. By using such a geopolimer slurry, the CO2 emissions can be significantly reduced compared to the case where cement is used as a hydraulic material, and the cured product has advantages such as excellent acid resistance and fire resistance. The mechanism of the curing reaction of geopolimer is shown by the following formula. This reaction is polymerization by polycondensation. The bonds of Si and Al contained in the aluminosilicate material are broken by alkali stimulation, and the contained Ca 2+ and Na + and other metal ions elute, and OH and metal ions react with each other to form monomers. While dehydrating, these monomers bond with metal ions to form polymers and cure. At the same time, these metal ions react with carbon dioxide in a carbonation reaction to form a cured product, and these reactions combine to form a strong composite cured body.

Chemical formula

[0040] The cured product of geopolymers is superior in fire resistance and acid resistance compared to the cured product of cement. This is presumably because different products from cement hydrates are formed depending on the chemical composition of the active filler. Aluminosilicate materials such as blast furnace slag and fly ash, which are commonly used as binders for geopolymers, have less Ca component compared to Portland cement, so the rate of change to gypsum by acid is low, and thus they are excellent in acid resistance. Also, since the main component of geopolymers is amorphous gel, there is an advantage that the strength reduction due to heating is small and it is excellent in high-temperature resistance.

[0041] Properties of slurry The slurry of the composition, after the formation of the slurry, from the start of the contact of the hydraulic material, water, and carbon dioxide until it completely loses fluidity and hardens, usually takes 1 hour or more, preferably 3 hours or more, more preferably 5 hours or more, even more preferably 10 hours or more, even more preferably 15 hours or more, most preferably 24 hours (1 day) or more or more than 24 hours (1 day). Here, the state where the slurry of the composition has not "completely lost fluidity and hardened" means that in a closed system, at 20°C, after a predetermined period has elapsed since the start of the contact between the slurry of the composition injected into a predetermined mold and carbon dioxide (concentration of at least 80%), it is impossible to demold at all from the mold (the adhesiveness of the slurry to the inner surface of the mold is still retained), or it is impossible to demold in a clean state to such an extent that substantially all of the inner surface shape of the mold is reflected in the outer shape of the cured product (for example, since not all parts are hardened, it is impossible to avoid part of the cured product being damaged during demolding).

[0042] Method for embedding space The space embedding method according to the present invention includes injecting a slurry containing the above composition into a space and reacting it with carbon dioxide injected into the space together with the slurry or carbon dioxide injected into the space separately from the slurry to embed this space. The space intended to be embedded by the space embedding method of the present invention is not particularly limited and includes spaces having any shape and volume. The space also includes spaces existing on the ground and spaces existing underground (for example, pores in strata, underground tunnels, coal mining traces, etc.). The volume of the space to be embedded is not limited in any way, but for example, it can be 10 -3 m 3 ~10 7 m 3 and may typically be 1 m 3 ~10 6 m 3 、1 m 3 ~10 5 m 3 、5 m 3 ~10 4 m 3 、5 m 3 ~10 3 m 3 、or 10 m 3 ~10 3 m 3 and may be such values.

[0043] The source of carbon dioxide used in the space embedding method according to the present invention is not particularly limited. In one embodiment, the carbon dioxide used in this method includes that discharged and recovered from power plants or various chemical plants such as petroleum refining facilities and ammonia manufacturing facilities.

[0044] The injection pressure of carbon dioxide injected into the space can be determined according to various factors such as the form of carbon dioxide, the pipe diameter and length of the conduit from the injection port to the space, and the shape and volume of the space to be embedded. The injection pressure of carbon dioxide is not particularly limited, but for example, it can be above atmospheric pressure and 100 MPaG or less, typically 1 MPaG or more and 50 MPaG, 2 MPaG or more and 40 MPaG or less, or 3 MPaG or more and 30 MPaG or less.

[0045] Examples of the space include the underground coal mining sites and tunnels in underground mining coal mines. Further examples of the space include underground buried pipes for various purposes such as sewers, water supply pipes, gas pipes, electric and communication cables, and service water pipes that are no longer in use due to aging, damage, etc. In particular, such underground coal mining sites and tunnels in closed coal mines, or underground buried pipes that are aged or damaged, often have the problem that the space to be filled is partially narrowed or complicated, such as deformation or flooding of underground cavities. For example, the space in the underground coal mining site of an underground mining coal mine includes not only a relatively continuous and large space but also a space in which extremely narrow passages filled with crushed stones and small stones are complexly connected. In addition, such underground coal mining sites and tunnels in underground mining coal mines may have a depth ranging from several hundred meters to over 1000 meters underground. According to the space embedding method of the present embodiment, carbon dioxide, which is a greenhouse gas, together with a solidifying substance having appropriate fluidity and solidifying characteristics, can be efficiently filled and solidified into every corner of the space to embed the space while suppressing solidification near the injection port in the space, particularly a space including at least a partially narrowed or complicated shape. In addition, the embedding efficiency and strength of the space can be increased, and a larger amount of carbon dioxide can be immobilized and mineralized, contributing to the prevention of global warming and environmental protection.

[0046] In one embodiment, when injecting a slurry of carbon dioxide and a composition into the space, before introducing them into the space, the slurry of carbon dioxide and the composition can be mixed in advance, that is, the paths of the slurry of carbon dioxide and the composition to the space can be made common. In a more preferred embodiment, when injecting a slurry of carbon dioxide and a composition into a space, without previously mixing the slurry of carbon dioxide and the composition, the slurry of carbon dioxide and the composition are introduced into the space through separate paths and configured to react only when they reach the space, so as to achieve filling of the slurry of the composition and immobilization of carbon dioxide. The separate paths include the case of using one conduit with a time difference and the case of using two (or three or more) separate conduits. In this embodiment, preferably, for example, by first filling the space to be filled with the slurry of the composition and then introducing carbon dioxide, early solidification can be prevented, the space can be reliably filled, and a larger amount of carbon dioxide can be immobilized. In any of the embodiments, preferably, after the slurry of the composition is generated and comes into contact with carbon dioxide, that is, after the contact of the hydraulic material, water, and carbon dioxide is initiated, until it completely loses fluidity and hardens, as long as the slurry of the composition reaches every corner of the space to be embedded, the supply conditions such as the supply rate (flow rate) and supply pressure of the slurry to the space can be adjusted as appropriate. The supply rate of the slurry to the space is not limited in any way, but for example, 10 -3 m 3 / min to 5·10 3 m 3 / min, typically 10 -3 m 3 / min to 10 3 m 3 / min, 10 -3 m 3 / min to 10 2 m 3 / min, 10 -2 m 3 / min to 10 3 m 3 / min, 10 -2 m 3 / min to 10 2 m 3 / min, 10 -1 m 3 / min to 10 2 m 3 / min, or 10 -1 m 3 / min to 10m 3 / min may be sufficient.

[0047] The carbon dioxide injected into the space dissolves in the water in the slurry to become carbonate ions or bicarbonate ions. These carbonate ions or bicarbonate ions combine with metal ions such as calcium ions derived from hydraulic materials, and solid metal carbonates (such as calcium carbonate) are formed, thereby fixing carbon dioxide. Not only the carbon dioxide gas injected into the space but also supercritical carbon dioxide may be used. Considering various factors such as the position, shape, and size of the space to be buried, and the types and amounts of the hydraulic material and optional components of the slurry, the properties of the carbon dioxide used can be appropriately selected from the viewpoints of the handleability and efficiency of the injection and immobilization of carbon dioxide. As the carbon dioxide gas, gas from liquid carbon dioxide, compressed carbon dioxide gas, gas from dry ice, carbon dioxide gas generated by chemical reaction, etc. can be used. The concentration of the carbon dioxide gas to be injected is preferably 75% or more, more preferably 80% or more, even more preferably 85% or more, still more preferably 90% or more, and most preferably 95% or more.

[0048] For example, when the carbon dioxide injected into the space reacts with calcium ions to form calcium carbonate, theoretically, 1 m 3 of carbon dioxide gas (25 °C, atmospheric pressure; mass about 1.98 kg) reacts with about 2.26 kg of calcium oxide. That is, it is understood that this reaction can absorb and immobilize carbon dioxide gas with a small amount of calcium component.

[0049] The amount of carbon dioxide buried, fixed, and mineralized in the space by the space burial method of any of the above embodiments depends on the type and amount of the hydraulic material and other optional components used in the slurry, the reaction rate of hardening determined thereby, and further on the supply procedure of the slurry and carbon dioxide to the space, and thus is not particularly limited. In one embodiment, the degree to which the composition slurry undergoes a curing reaction with carbon dioxide and becomes immobilized is determined by introducing the slurry and a saturated amount of carbon dioxide into a closed system, and measuring, for example, the amount of carbon dioxide adsorbed per unit volume of the slurry after 30 minutes (the amount of carbon dioxide reduced in the system: kg / m 3 ). The amount of carbon dioxide adsorbed 30 minutes after the composition slurry starts to contact carbon dioxide is preferably 50 kg / m 3 or more, more preferably 100 kg / m 3 or more, even more preferably 200 kg / m 3 or more, and most preferably 300 kg / m 3 or more.

[0050] Also, the amount of carbon dioxide that is embedded in the space and becomes immobilized and mineralized can be grasped by subjecting the product of the curing reaction between the metal ions derived from the hydraulic material and carbon dioxide (for example, calcium carbonate: CaCO3) to thermogravimetric differential thermal analysis (TG-DTA) and analyzing the amount of carbon dioxide:CO2 immobilized per unit weight of the product (that is, the ratio of the weight reduced by thermogravimetric differential thermal analysis). When the product of the curing reaction between the metal ions derived from the hydraulic material and carbon dioxide is calcium carbonate (CaCO3), since the decomposition temperature is about 230°C to about 730°C, it can be subjected to thermogravimetric differential thermal analysis within this temperature range, and the ratio of the reduced weight per unit weight of the product can be analyzed. That is, the amount of carbon dioxide immobilized (%)W CO2 is calculated as follows. Let the mass obtained by subtracting the mass of free moisture from the mass of the product sample of the curing reaction be m0 (mg), and the mass reduced within a predetermined temperature range by thermogravimetric differential thermal analysis (for calcium carbonate, the mass reduced between about 230°C and about 730°C; that is, the mass of carbon dioxide generated by the thermal decomposition of calcium carbonate) be m1 (mg). W CO2 =(m1 / m0)×100 (%)

[0051] The amount of carbon dioxide embedded and immobilized / mineralized in the space is the fixed amount of carbon dioxide W at the time when 14 days (i.e., two weeks) have elapsed since the contact between the slurry (including hydraulic material, optional components, and water) and carbon dioxide was initiated. CO2 It is preferably 2.0% or more, more preferably 4.0% or more, even more preferably 5.0% or more, still more preferably 6.0% or more, even still more preferably 7.0% or more, and most preferably 8.0% or more.

[0052] In a preferred embodiment, it is also preferable to provide an exhaust duct for unreacted (unimmobilized) carbon dioxide among the carbon dioxide injected into the space. When the space to be embedded is a substantially closed system, the substantial amount of immobilized carbon dioxide can be measured from the difference and variation between the injection amount and the exhaust amount of carbon dioxide, and the temporal change in the carbon dioxide immobilization ability of the hydraulic material can be grasped. In such a case, when the carbon dioxide concentration in the exhaust gas reaches a predetermined threshold value, for example, 80% or more or 90%, it can be determined that the carbon dioxide immobilization ability by the hydraulic material is approaching a saturated state, and thus it is possible to judge to stop the injection of carbon dioxide.

[0053] Figure 1 is a schematic view of an embodiment in which the method for embedding a space or the space embedding system according to the present invention is applied to an underground coal mining site of an underground coal mine. It should be noted that this is a non-limiting example. In Figure 1, 1 is a space embedding system, 2 is a carbon dioxide storage facility, 3 is a carbon dioxide injection well, 4 is a carbon dioxide injection conduit, 5 is an underground aquifer, 6 is a coal seam, 7 is an underground coal mining site of an underground coal mine, and 8 refers to the space to be embedded. Carbon dioxide (e.g., liquefied or supercritical fluid) discharged and recovered from various chemical plants such as power plants, oil refineries, or ammonia manufacturing facilities is first stored in a storage facility 2 such as a tank, and then is usually injected and filled through an injection conduit 4 from a carbon dioxide injection well 3 into a space 8 to be buried. The pressure inlet of the carbon dioxide injection well 3 may usually be equipped with a pump for reliably delivering carbon dioxide to the space. The underground mining sites 7 of underground coal mines are often located deep underground, for example, at depths exceeding several hundred meters to over 1000 meters underground. In such cases, the carbon dioxide injection conduit 4 is arranged in a form that passes through the underground aquifer 5 and reaches the underground mining sites 7 of the underground coal mines existing in the coal seam 6 and the space 8 to be buried therein.

[0054] Preferably, prior to the injection and filling of this carbon dioxide into the space 8, a slurry of a composition containing a hydraulic material is fed and filled into the space 8. Although the conduit for feeding the composition slurry into the space 8 is not shown, the conduit may be common with the carbon dioxide injection conduit 4 or may be provided separately. The injection rate (and pump pressure) of carbon dioxide into the space 8 and the feeding rate of the composition slurry are not particularly limited as long as the slurry of the composition reaches every corner of the space to be buried before it completely loses fluidity and hardens after coming into contact with carbon dioxide. Preferably, when injecting carbon dioxide and the composition slurry into the space, without previously mixing the carbon dioxide and the composition slurry, the composition slurry is first introduced into the space to be buried through a (temporally or physically) separated path, and then carbon dioxide is introduced into the space, and they are configured to react only when they reach the space, so as to achieve the filling of the composition slurry and the immobilization of carbon dioxide. According to this embodiment, it is possible to efficiently fill and solidify every corner of the space to bury the space while suppressing the solidification of the composition slurry near the injection port in a space including a shape that is at least partially narrowed or complicated, thereby increasing the embedding efficiency and strength of the space, enabling more carbon dioxide to be immobilized and mineralized, and contributing to the prevention of global warming and environmental protection.

Example

[0055] Hereinafter, based on the examples, the effects of the present invention will be described in more detail. Note that the present invention is not limited to these examples.

[0056] Substances used (1) Hydraulic material (binder) · Granulated blast furnace slag fine powder: "Spirits 4000" (trade name) manufactured by Nippon Steel & Sumitomo Metal Corporation Density 2.91 g / cm 3 , Specific surface area 4050 cm 2 / g · Fly ash: Manufactured by Kitadenko Co., Ltd. Composition - SiO2: 58.4%, Al2O3: 23.2%, Fe2O3: 5.9%, CaO: 3.7%, SO3: 1.0%, MgO: 0.8%

[0057] (2) Alkali stimulant Sodium hydroxide (3) Dispersant "JW-7" (polycarboxylic acid ether polymer) "MJ-3" (polycarboxylic acid polymer) (4) Chelating agent (metal eluent) "CY-1" (also functions as a dispersant.) (5) Setting retarder "KS-1" (sodium gluconate)

[0058] Example 1 Using granulated blast furnace slag as the hydraulic material (binder), the mass ratio of water to granulated blast furnace slag (W / B) was set to 0.35, and granulated blast furnace slag and water were placed in a beaker. Then, after kneading these in a mixer for 1 minute at 20°C, scraping them off for 1 minute, and further kneading them in a mixer for 4 minutes, Composition Slurry 1 was obtained. Then, this Composition Slurry 1 was cured in a carbon dioxide (CO2)-promoting environment (i.e., in an environment of 100% carbon dioxide) to obtain Composition Slurry 1' into which carbon dioxide was injected.

[0059] Example 2 In addition to blast furnace slag as a hydraulic material (binder) and water, sodium hydroxide (NaOH) was added to the beaker in an amount such that the mass ratio (Na2O / B) of Na2O from sodium hydroxide to the hydraulic material (binder) was 0.045. Otherwise, in the same manner as in Example 1 above, composition slurry 2 and composition slurry 2' into which carbon dioxide was injected were obtained.

[0060] Example 3 Blast furnace slag and water were placed in a beaker with the mass ratio of water to blast furnace slag as a hydraulic material (binder) (W / B) being 0.5. In addition to this, sodium hydroxide (NaOH) was added to the beaker in an amount such that the mass ratio (Na2O / B) of Na2O from sodium hydroxide to the hydraulic material (binder) was 0.09. Otherwise, in the same manner as in Example 1 above, composition slurry 3 and composition slurry 3' into which carbon dioxide was injected were obtained.

[0061] Example 4 Fly ash was used as the hydraulic material (binder). Fly ash and water were placed in a beaker with the mass ratio of water to fly ash (W / B) being 0.4. In addition to this, sodium hydroxide (NaOH) was added to the beaker in an amount such that the mass ratio (Na2O / B) of Na2O from sodium hydroxide to the hydraulic material (binder) was 0.148. Otherwise, in the same manner as in Example 1 above, composition slurry 4 and composition slurry 4' into which carbon dioxide was injected were obtained.

[0062] Example 5 Fly ash was used as a hydraulic material (binder), and fly ash and water were put into a beaker with the mass ratio of water to fly ash (W / B) being 0.5. In addition, sodium hydroxide (NaOH) was added to the beaker as an alkali stimulant in an amount such that the mass ratio of Na2O from sodium hydroxide to the hydraulic material (binder) (Na2O / B) was 0.185. Except for this, the composition slurry 5 and the composition slurry 5' injected with carbon dioxide were obtained in the same manner as in Example 1 above.

[0063] (i) Measurement of fluidity (flow characteristics) of the composition slurry For each of the above composition slurries 1 to 5, the fluidity (flow characteristics) after stirring at room temperature (about 20 °C) for 5 minutes was measured. The measurement of fluidity was carried out in accordance with the "Physical Testing Methods of Cement" of JIS-R-5201. Using a flow table, a flow cone, and a tamping rod, the sample of the composition slurry was packed in two layers in the flow cone, with each layer being tamped evenly 15 times. The diameter of the slurry after the dropping motion was given to the paste to spread it was measured in the direction where the maximum was recognized and the direction perpendicular to this, and the flow value was obtained. When the dropping motion was impossible, a flat plate for the slump test was used, and the measurement was carried out 30 seconds after the flow cone was pulled up.

[0064] (ii) Measurement of the compressive strength of the composition slurry after curing in a carbon dioxide atmosphere for 14 days After each of the above composition slurries 1 to 5 was formed, the composition slurry was kneaded for 1 minute, scraped for 1 minute, and then kneaded for another 4 minutes. A cylindrical plastic mold with a diameter of φ50 × 100 (mm) was used as the mold. The kneaded slurry was divided into two layers and put into the mold. After each layer was tamped 15 times with a tamping rod, it was leveled with a wooden mallet and a trowel. For the slurry introduced into the formwork in this way, the compressive strength after curing for 14 days under an atmosphere of 80% or more carbon dioxide at room temperature (about 20°C) was measured in accordance with the concrete compression test method of JIS A1108. The samples were demolded at an age of 1 day and cured. Samples that could not be demolded at 1 day (after 24 hours), that is, samples in which the adhesiveness of the slurry to the inner surface of the formwork was retained, were cured without being demolded. After curing for 14 days under a carbon dioxide atmosphere, the driving surface was polished so that the load was applied uniformly. A load was uniformly applied using a compressive strength testing machine to such an extent that no impact was given, and the loading speed was about 0.6 ± 0.4 (N / mm 2 ). The compressive strength was calculated by reading the maximum load indicated by the testing machine when the target sample was destroyed up to 0.5 (kN) and dividing this by the cross-sectional area of the sample. Here, if, 1 day after the start of curing of the premixed slurry under a carbon dioxide atmosphere (after 24 hours), it is impossible to demold, that is, the adhesiveness of the slurry to the inner surface of the formwork is retained, or it is in a state where it is impossible to demold in a clean state to such an extent that substantially all of the inner surface shape of the formwork is reflected in the outer shape of the cured product (for example, since not all parts are cured, it is impossible to avoid partial damage to the cured product during demolding), then this slurry can be judged as "not cured". Conversely, if, 1 day after the start of curing of the premixed slurry under a carbon dioxide atmosphere (after 24 hours), it is possible to demold, that is, the adhesiveness of the slurry to the inner surface of the formwork is not retained, or it is in a state where it is possible to demold in a clean state to such an extent that substantially all of the inner surface shape of the formwork is reflected in the outer shape of the cured product, then this slurry can be judged as "cured".

[0065] (iii) Carbon dioxide fixation amount and calcium carbonate (CaCO 3 ) Production amount measurement of the composition slurry after curing in a carbon dioxide atmosphere for 14 days The sample obtained after curing for 14 days in a carbon dioxide atmosphere in (ii) above was immersed in isopropanol for 15 minutes, suction filtration was performed for 1 minute, and it was pre-treated by drying in a 40 °C chamber for 7 minutes. The amount of the measurement sample was set to 10 ± 1 mg, the temperature was raised at 20 °C / min under a nitrogen atmosphere, maintained for 5 minutes after reaching 1000 °C, and then thermogravimetric differential thermal analysis (TG-DTA) was performed to grasp the amount of carbon dioxide fixation under the cooling conditions. When the product of the curing reaction between the metal ions derived from the hydraulic material and carbon dioxide is calcium carbonate (CaCO3), since the decomposition temperature is about 230 °C to about 730 °C, by analyzing the ratio of the weight loss per unit weight of the product therefrom, the amount of carbon dioxide fixation (%) and further the amount of calcium carbonate (CaCO3) generation (%) can be quantified. Amount of carbon dioxide fixation (%) W CO2 Let the mass obtained by subtracting the mass of free moisture from the mass of the sample (the product of the curing reaction between the hydraulic material of the slurry and carbon dioxide) be m0 (mg), and the mass decreased within the above temperature range by thermogravimetric differential thermal analysis (the mass decreased between about 230 °C and about 730 °C for calcium carbonate: that is, the mass of carbon dioxide generated by the thermal decomposition of calcium carbonate) be m1 (mg), then it can be calculated by the following calculation formula. W CO2 =(m1 / m0)×100(%) Also, the amount of calcium carbonate (CaCO3) generation (%) W CaCO3 (The mass ratio of calcium carbonate in the sample after the curing treatment) can be calculated by the following calculation formula from the reaction formula of thermal decomposition CaCO3 (molecular weight 100) → CaO (molecular weight 56) + CO2 (molecular weight 44). W CaCO3 =W CO2 ×(100 / 44)(%) Furthermore, from the amount of CaCO3 generated, the amount of CO2 fixation per slurry volume (kg / m 3 ) was calculated.

[0066] The measurement results of the physical properties (i) to (iii) for Composition Slurries 1 to 5 (Examples 1 to 5) are shown in Table 1 below together with the mass ratio of water to hydraulic material (binder) (W / B) and the mass ratio of Na2O from sodium hydroxide (NaOH) of the alkali stimulant to hydraulic material (binder) (Na2O / B).

[0067] [Table 1]

[0068] From the results shown in Table 1, according to the method for embedding a space according to the present invention, by adjusting the type and amount of the hydraulic material of the composition and the presence or amount of the alkali stimulant, the fluidity and hardening rate can be controlled within an appropriate range, and while efficiently filling the space, it is understood that a larger amount of carbon dioxide can be embedded and solidified.

[0069] Example 6 Using blast furnace slag as the hydraulic material (binder), putting blast furnace slag and water into a beaker with the mass ratio of water to blast furnace slag (W / B) being 0.35, and further adding the dispersant "JW-7" at a mass ratio (in terms of solid content) of 0.018% by mass to the blast furnace slag, and mixing by hand for 30 seconds at room temperature (about 20°C) to obtain Composition Slurry 6.

[0070] Example 7 Composition Slurry 7 was obtained in the same manner as in Example 6 except that the chelating agent "CY-1" (which also functions as a dispersant) with a mass ratio (in terms of solid content) of 0.2% by mass to the blast furnace slag was added as a slurry component instead of the dispersant "JW-7".

[0071] Example 8 Using blast furnace slag as a hydraulic material (binder), with the mass ratio of water to blast furnace slag (W / B) set to 0.35, blast furnace slag and water were placed in a beaker. Additionally, NaOH as an alkali stimulant in an amount such that the mass ratio of Na2O from sodium hydroxide (NaOH) to the hydraulic material (binder) (Na2O / B) was 0.045, and a dispersant "MJ-3" with a mass ratio (in terms of solid content) of 0.2 mass% to blast furnace slag were added. At room temperature (about 20 °C), it was manually kneaded and mixed for 30 seconds to obtain composition slurry 8.

[0072] Example 9 The mass ratio (in terms of solid content) of the dispersant "MJ-3" to blast furnace slag was changed to 0.15 mass%, and further, except that a setting retarder "KS-1" with a mass ratio (in terms of solid content) of 0.2 mass% to blast furnace slag was added as a slurry component, it was carried out in the same manner as in Example 8 to obtain composition slurry 9.

[0073] The component compositions of composition slurries 6 - 9 (Examples 6 - 9) are shown in Table 2 below. In Table 2, "mass% / B" indicates the mass percentage of the component with respect to the hydraulic material (binder) (the same applies to Table 3).

Table 2

[0074] Composition slurries 6 - 9 (Examples 6 - 9) were subjected to measurement tests for each of the physical properties (i) - (iii) above. Here, in the measurement of the compressive strength of the composition slurry in (ii) above, when the sample could be demolded at the time of curing for 1 day (24 hours) in a carbon dioxide atmosphere, the compressive strength was measured. Also, in the measurement of the carbon dioxide fixation amount of the composition slurry in (iii) above, the values were measured after curing for 1 day (24 hours) and after curing for 14 days in a carbon dioxide atmosphere.

[0075] The measurement results of each of the physical properties (i) - (iii) for composition slurries 6 - 9 (Examples 6 - 9) are shown in Table 3 below.

Table 3

[0076] From the results shown in Table 3, according to the method for embedding a space according to the present invention, even when the composition does not contain an alkali stimulant, it was found that the fixed amount of carbon dioxide can be increased by adding an appropriate additive. In particular, a high fixed amount of carbon dioxide was obtained when a chelating agent was added. When the composition contained an alkali stimulant, the fixed amount of carbon dioxide was larger than when it did not contain it. When the composition contains an alkali stimulant, while the fixed amount of carbon dioxide increases, the curing rate also tends to be higher. However, in addition to being able to control the curing rate to be low by adding a curing inhibitor as an additive, it was found that curing progresses after 14 days of curing in a carbon dioxide atmosphere and reaches an appropriate strength. Thus, according to the method for embedding a space according to the present invention, regardless of the presence or absence of an alkali stimulant, a delayed curing rate on a daily basis can be obtained, making it possible to achieve reliable filling and embedding even in a space with a complex shape up to every corner. Note that the present invention may include the embodiments or implementation forms exemplified below. [1]. A method for embedding a space, comprising: Preparing a composition containing a hydraulic material and at least one selected from the group consisting of an alkali stimulant, a dispersant, and a setting inhibitor; and Injecting a slurry containing the composition into the space and reacting it with carbon dioxide injected into the space together with the slurry or carbon dioxide injected into the space separately from the slurry to embed the space. [2]. The method according to item [1] above, wherein the space includes at least one selected from the group consisting of pores in a formation, underground tunnels, and coal mining traces. [3]. The method according to item [1] or [2] above, wherein the hydraulic material includes an aluminosilicate material. [4]. The method according to item [3] above, wherein the aluminosilicate material includes blast furnace slag. [5]. The method according to item [1] or [2] above, wherein the alkali stimulant includes sodium hydroxide. [6]. The method according to item [1] or [2] above, wherein the dispersant includes a polycarboxylic acid-based polymer. [7]. The method according to item [1] or [2] above, wherein the setting inhibitor includes at least one selected from the group consisting of oxycarboxylic acid or its salt, keto acid or its salt, sugar, and sugar alcohol. [8]. A space embedding system, comprising: A slurry preparation unit for preparing a slurry using a composition containing a hydraulic material and at least one selected from the group consisting of an alkali stimulant, a dispersant, and a setting inhibitor; A slurry injection unit for injecting the slurry, or the slurry and carbon dioxide, into the space; and When the slurry injection unit is a slurry injection unit that injects the slurry into the space without carbon dioxide, a carbon dioxide injection unit for separately injecting carbon dioxide into the space.

Explanation of Signs

[0077] 1: Space embedding system 2: Carbon dioxide storage facility 3: Carbon dioxide injection well 4: Carbon dioxide injection conduit 5: Underground aquifer 6: Coal seam 7: Underground coal mining site of an underground coal mine 8: Space to be embedded

Claims

Claim 1 A method for filling an underground space using a shaft, comprising: preparing a composition containing a hydraulic material and at least one selected from the group consisting of an alkali stimulant, a dispersant, and a hardening inhibitor; and pressurizing a slurry containing the composition into the underground space using the shaft, and reacting the slurry with carbon dioxide to fill the underground space, the reaction being carried out by (i) forming a mixture of the slurry and carbon dioxide prior to introducing the slurry and carbon dioxide into the underground space and then pressurizing the mixture into the underground space, or (ii) filling the underground space with the slurry and then introducing carbon dioxide into the underground space. Claim 2 The method according to claim 1, wherein the underground space includes at least one selected from the group consisting of pores in a formation, underground tunnels, and coal mining traces. Claim 3 The method according to claim 1 or 2, wherein the hydraulic material includes an aluminosilicate material. Claim 4 The method according to claim 3, wherein the aluminosilicate material includes blast furnace slag. Claim 5 The method according to claim 1 or 2, wherein the alkali stimulant includes sodium hydroxide. Claim 6 The method according to claim 1 or 2, wherein the dispersant includes a polycarboxylic acid polymer. Claim 7 The method according to claim 1 or 2, wherein the hardening inhibitor includes at least one selected from the group consisting of an oxycarboxylic acid or its salt, a keto acid or its salt, a sugar, and a sugar alcohol. Claim 8 A method for filling an underground space using a shaft, comprising: preparing a composition containing an aluminosilicate material and an alkali stimulant; adding a dispersant or a hardening inhibitor to the composition; and pressurizing a slurry containing the composition into the underground space using the shaft, and reacting the slurry with carbon dioxide to fill the underground space, the reaction being carried out by (i) forming a mixture of the slurry and carbon dioxide prior to introducing the slurry and carbon dioxide into the underground space and then pressurizing the mixture into the underground space, or (ii) filling the underground space with the slurry and then introducing carbon dioxide into the underground space. Claim 9 The method according to claim 8, wherein the aluminosilicate material contains blast furnace slag and the alkali stimulant contains sodium hydroxide. **Claim 10** The method according to claim 8 or 9, wherein the dispersant contains a polycarboxylic acid polymer. **Claim 11** The method according to claim 8 or 9, wherein the hardening inhibitor contains at least one selected from the group consisting of oxycarboxylic acids or their salts, keto acids or their salts, sugars, and sugar alcohols.

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