CaO-containing composition, method for producing calcium carbonate compound, calcium carbonate compound, inorganic molded body, and method for increasing CO2 fixation rate of inorganic molded body

Abstract

Provided are a CaO-containing composition that reduces the burden on the environment and allows a carbonation reaction to proceed efficiently, a method for producing a calcium-based carbonate compound using the CaO-containing composition, a calcium-based carbonate compound, an inorganic molded body, and a method for increasing the CO2 fixation rate of an inorganic molded body. [Solution] A CaO-containing composition having a free CaO content of 15% by mass or more and less than 50% by mass, an SiO2 content of 5% by mass or more and 50% by mass or less, an Al2O3 content of 1% by mass or more and 20% by mass or less, and an Fe2O3 content of 0.5% by mass or more and 15% by mass or less, and an average particle size measured by a laser diffraction method of 1 μm or more and 50 μm or less.

Description

[Technical Field]

[0001] The present invention relates to a CaO-containing composition, a method for producing a calcium carbonate compound, a calcium carbonate compound, an inorganic molded body, and a method for increasing the CO2 fixation rate of an inorganic molded body. [Background technology]

[0002] In recent years, there has been growing interest in environmental awareness, including issues such as global warming, and calls for reducing carbon dioxide emissions into the atmosphere. In response, attempts are being made to reuse by-products and by-produced energy, such as waste, exhaust gases such as carbon dioxide, and waste heat, generated at industrial facilities such as incinerators, steel mills, and cement plants.

[0003] For example, waste concrete is discarded in huge quantities, and therefore there is a demand for its reuse from the viewpoints of saving natural resources, protecting the environment, and making effective use of resources.

[0004] The concrete waste is a waste material containing calcium, and a technique has been proposed for producing calcium carbonate by carbonating the waste material with carbon dioxide (see Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-69860 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when calcium carbonate is produced using calcium contained in concrete waste or the like, the production process is complicated, and the carbonation reaction cannot be easily and efficiently advanced, which also poses an economic problem.

[0007] Therefore, an object of the present invention is to provide a CaO-containing composition that reduces the burden on the environment and can efficiently promote a carbonation reaction, a method for producing a calcium-based carbonate compound using the CaO-containing composition, a calcium-based carbonate compound, an inorganic molded body, and a method for increasing the CO2 fixation rate of an inorganic molded body. [Means for solving the problem]

[0008] As a result of extensive research, the present inventors have found that the above-mentioned problems can be solved by the following configuration, and have thus completed the present invention.

[0009] That is, the present invention relates to a CaO-containing composition having a free CaO content of 15% by mass or more and less than 50% by mass, an SiO2 content of 5% by mass or more and 50% by mass or less, an Al2O3 content of 1% by mass or more and 20% by mass or less, and an Fe2O3 content of 0.5% by mass or more and 15% by mass or less, and an average particle size measured by a laser diffraction method of 1 μm or more and 50 μm or less.

[0010] The CaO-containing composition of the present invention preferably has an SO3 content of 0.8 mass % or more and 10 mass % or less.

[0011] The CaO-containing composition of the present invention is preferably a pulverized product of a CaO-containing raw material.

[0012] In the CaO-containing composition of the present invention, the CaO-containing raw material is preferably derived from at least one of paper sludge incineration ash, chicken manure incineration ash, cement sludge, cement sludge incineration ash, and hydrates thereof.

[0013] The CaO-containing composition of the present invention has a BET specific surface area of ​​1 m 2 / g or more 100m 2 / g or less is preferable.

[0014] The CaO-containing composition of the present invention is preferably for recycling.

[0015] The present invention relates to a method for producing a calcium-based carbonate compound, which includes a preparation step of preparing the CaO-containing composition, and a carbonation step of contacting the CaO-containing composition with carbon dioxide (carbon dioxide gas) to form a calcium-based carbonate compound.

[0016] In the method for producing a calcium-based carbonate compound of the present invention, the preparation step preferably includes a pulverization step of pulverizing a CaO-containing raw material.

[0017] In the method for producing a calcium carbonate compound of the present invention, the concentration of carbon dioxide in the carbonation step is preferably 1% by volume or more and 50% by volume or less.

[0018] In the method for producing a calcium carbonate compound of the present invention, the carbon dioxide in the carbonation step is preferably carbon dioxide emitted from a combustion engine.

[0019] In the method for producing a calcium carbonate compound of the present invention, the temperature in the carbonation step is preferably 5°C or higher and 95°C or lower.

[0020] The present invention relates to calcium carbonate compounds, which are carbonates of the CaO-containing compositions.

[0021] The calcium carbonate compound of the present invention preferably has an SiO2 content of 5% by mass or more and 50% by mass or less, an Al2O3 content of 1% by mass or more and 20% by mass or less, an Fe2O3 content of 0.5% by mass or more and 15% by mass or less, and an average particle size measured by a laser diffraction method of 1 μm or more and 50 μm or less.

[0022] The calcium carbonate compound of the present invention preferably has an SO3 content of 0.8% by mass or more and 10% by mass or less.

[0023] The calcium carbonate compound of the present invention preferably has a CO2 fixation rate of 5 mass % or more.

[0024] The calcium carbonate compound of the present invention has a BET specific surface area of ​​5 m 2 / g or more 200m 2 / g or less is preferable.

[0025] The calcium carbonate compound of the present invention preferably contains calcite.

[0026] The calcium carbonate compound of the present invention is preferably used for inorganic formed bodies.

[0027] The present invention relates to an inorganic formed body containing the calcium carbonate compound.

[0028] The present invention relates to a calcium carbonate compound containing CaCO3, which has an SiO2 content of 5% by mass or more and 50% by mass or less, an Al2O3 content of 1% by mass or more and 20% by mass or less, and an Fe2O3 content of 0.5% by mass or more and 15% by mass or less, and has an average particle diameter of 1 μm or more and 50 μm or less as measured by a laser diffraction method. system Concerning carbonate compounds.

[0029] The present invention relates to a calcium carbonate compound containing CaCO3, which has an SiO2 content of 5% by mass or more and 50% by mass or less, an Al2O3 content of 1% by mass or more and 20% by mass or less, and an Fe2O3 content of 0.5% by mass or more and 15% by mass or less, and has an average particle size of 1 μm or more and 50 μm or less as measured by a laser diffraction method.

[0030] The calcium carbonate compound of the present invention preferably has a CaCO3 content of 10 mass % or more.

[0031] The calcium carbonate compound of the present invention is preferably obtained using carbon dioxide emitted from a combustion engine.

[0032] Standard abbreviations for elements from the periodic table of the elements are used herein, e.g., C for carbon, Ca for calcium, O for oxygen, H for hydrogen, Si for silicon, Fe for iron, Al for aluminum, S for sulfur, and similarly for other elements.

[0033] In this specification, "free CaO" refers to unreacted CaO (calcium oxide) that has not combined with other substances. The methods for measuring the content of free CaO, as well as the composition and physical properties, are as described in the Examples unless otherwise specified.

[0034] In this specification, the term "calcium carbonate compound" refers to a compound containing calcium carbonate, and is a concept that allows the inclusion or coexistence of other subcomponents that may be incorporated during the manufacturing process, etc. [Effects of the Invention]

[0035] The present invention provides a CaO-containing composition that reduces the environmental load and allows the carbonation reaction to proceed efficiently, a method for producing a calcium carbonate compound using the CaO-containing composition, a calcium carbonate compound, an inorganic molded body, and a method for increasing the CO2 fixation rate of an inorganic molded body, all of which are useful. In particular, the use of the calcium carbonate compound allows the production of an inorganic molded body with increased strength. [Brief explanation of the drawings]

[0036] [Figure 1] FIG. 1 is a cross-sectional view showing a schematic diagram of a measuring device for measuring the content of CO2. [Figure 2] 1 is a SEM photograph of the calcium carbonate compound of Example 2-1 of the present invention. [Figure 3] 1 is an SEM photograph of the calcium carbonate compound of Example 2-2 of the present invention. [Figure 4] 1 is an SEM photograph of the calcium carbonate compound of Example 2-3 of the present invention. [Figure 5] 1 is an SEM photograph of a calcium carbonate compound of Comparative Example 2-1 of the present invention. [Figure 6]It is a partial perspective view schematically showing a heating tester.

Embodiments for Carrying out the Invention

[0037] The CaO-containing composition, the method for producing a calcium-based carbonate compound, the calcium-based carbonate compound, the inorganic molded body, and the method for increasing the CO2 immobilization rate of the inorganic molded body of the present invention will be described below. The present invention is not limited to these embodiments.

[0038] <CaO-containing composition> The present invention relates to a CaO-containing composition in which the content of free CaO is 15% by mass or more and less than 50% by mass, the content of SiO2 is 5% by mass or more and 50% by mass or less, the content of Al2O3 is 1% by mass or more and 20% by mass or less, the content of Fe2O3 is 0.5% by mass or more and 15% by mass or less, and the average particle diameter by the laser diffraction method is 1 μm or more and 50 μm or less.

[0039] The CaO-containing composition preferably has a free CaO content of 15% by mass or more and less than 50% by mass, more preferably 18% by mass or more and 49% by mass or less, and even more preferably 20% by mass or more and 48% by mass or less. By using a CaO-containing composition with a low CaO content, a raw material with reduced environmental load can be used. Also, in the carbonation step of producing a calcium-based carbonate compound using the CaO-containing composition, the carbonation reaction can proceed efficiently without adding seed crystals or performing other operations (steps), and the calcium-based carbonate compound can be obtained, which is useful.

[0040] [[ID= / / ]] The CaO-containing composition preferably has a SiO2 content of 5% by mass or more and 50% by mass or less, more preferably 8% by mass or more and 48% by mass or less, and even more preferably 10% by mass or more and 45% by mass or less. Thereby, the strength of the inorganic molded body containing the calcium-based carbonate compound obtained using the CaO-containing composition can be improved.

[0041] The CaO-containing composition has an Al2O3 content of 1% by mass to 20% by mass, preferably 2% by mass to 18% by mass, and more preferably 3% by mass to 15% by mass, which can improve the strength of an inorganic formed body containing a calcium carbonate compound obtained using the CaO-containing composition.

[0042] The CaO-containing composition has an Fe2O3 content of 0.5 to 15% by mass, preferably 1 to 12% by mass, and more preferably 1.5 to 10% by mass, which can improve the strength of an inorganic formed body containing a calcium carbonate compound obtained using the CaO-containing composition.

[0043] The CaO-containing composition has an average particle size measured by a laser diffraction method of 1 μm to 50 μm, preferably 1.5 μm to 45 μm, more preferably 2 μm to 40 μm, and even more preferably 2.5 μm to 35 μm, thereby obtaining a CaO-containing composition having high reactivity with carbon dioxide.

[0044] The CaO-containing composition preferably has an SO content of 0.8% by mass to 10% by mass, more preferably 0.9% by mass to 9% by mass, and even more preferably 1.0% by mass to 8% by mass, which makes it easier to control the curing time of an inorganic molded body containing a calcium carbonate compound obtained using the CaO-containing composition, and allows for the production of an inorganic molded body with high strength.

[0045] The CaO-containing composition is preferably a pulverized product of a CaO-containing raw material, which has a larger surface area than the CaO-containing raw material before pulverization, and is therefore preferred because it facilitates the carbonation reaction in the subsequent carbonation step for producing a calcium carbonate compound.

[0046] The CaO-containing composition is preferably derived from at least one of the following: incineration ash of paper sludge, incineration ash of chicken manure, cement sludge, incineration ash of cement sludge, and hydrates thereof. Various materials can be used as the CaO-containing raw material, but the use of waste materials is preferred from the viewpoints of economy and waste reduction. Waste materials derived from the incineration ash of paper sludge and the incineration ash of chicken manure have a relatively high content of free CaO, which reduces the environmental load and makes it possible to easily and efficiently obtain a CaO-containing composition.

[0047] The CaO-containing composition has a BET specific surface area of ​​1 m 2 / g or more 100m 2 / g or less, and 2 / g or more 60m 2 / g or less is more preferable, and 2 / g or more 30m 2 / g or less, it is more preferable that the CaO content is 1 / g or less. This makes it possible to obtain a CaO-containing composition having high reactivity with carbon dioxide.

[0048] The CO2 content in the CaO-containing composition is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less. While a lower CO2 content is preferable, it may be 0.5% by mass or more, 1% by mass or more, or even 1.5% by mass or more. The CO2 is mainly derived from calcium carbonate. By keeping the CO2 content low, the free CaO content can be increased.

[0049] The CaO-containing composition of the present invention is preferably for recycling. As described above, the raw materials for the CaO-containing composition can be incineration ash of paper sludge, incineration ash of chicken manure, etc. When these raw materials are waste materials, they can be reused, which is useful from the viewpoints of saving natural resources, protecting the environment, and making effective use of resources.

[0050] <Method of manufacturing calcium carbonate compounds> The method for producing a calcium-based carbonate compound preferably includes a preparation step of preparing the CaO-containing composition and a carbonation step of contacting the CaO-containing composition with carbon dioxide to form a calcium-based carbonate compound, thereby improving the CO2 fixation rate in the resulting calcium-based carbonate compound.

[0051] (Crushing process) The method for producing a calcium-based carbonate compound preferably includes, as the preparation step, a pulverization step of pulverizing a CaO-containing raw material. By the grinding process, free CaO particles (or free (CaO) m (H2O) n By pulverizing the CaO particles, it is possible to make the particles finer, and it is possible to prepare a CaO-containing composition that has high reactivity with carbon dioxide. The CaO-containing raw material may be either a sieved product that has undergone a sieving process in which the CaO-containing raw material is sieved and the fraction that passes through the sieve is recovered in addition to the crushing process as the preparation process, or an unsieved product that has not undergone the sieving process. However, from the viewpoint of simplification of the manufacturing process and economic efficiency, an unsieved product that has not undergone the sieving process is preferred.

[0052] The pulverization method is not particularly limited, and a method using a known pulverizer can be adopted. Examples of pulverizers include roller mills, jet mills, high-speed rotary pulverizers such as hammer mills, cutter mills, and pin mills, container-driven mills such as rotary mills, vibration mills, and planetary mills, and media-agitating mills such as attritors, bead mills, ball mills, and rod mills.

[0053] The grinding time can be appropriately set in consideration of the content of free CaO in the target CaO-containing composition, particle size, etc. The grinding time is preferably from 10 seconds to 168 hours, more preferably from 10 minutes to 72 hours, and even more preferably from 30 minutes to 24 hours.

[0054] When a rotary mill such as a ball mill or a pot mill is used as the pulverizer, the rotation speed is preferably 10 rpm or more and 300 rpm or less, more preferably 50 rpm or more and 200 rpm or less, and even more preferably 60 rpm or more and 150 rpm or less.

[0055] The pulverization step may be carried out by either a dry method or a wet method. When the pulverization step is carried out by a wet method, water is usually used as a dispersion medium. The concentration of the CaO-containing raw material when dispersed in water can be appropriately set in consideration of pulverization efficiency, etc. The amount of the CaO-containing raw material mixed per liter of water is preferably 10 g or more and 1000 g or less, more preferably 80 g or more and 500 g or less, and even more preferably 120 g or more and 400 g or less.

[0056] When the grinding step is carried out wet, the suspension may be directly subjected to the subsequent carbonation step, or may be dried before being subjected to the subsequent carbonation step.

[0057] As described above, by carrying out the pulverization step as the preparation step, a CaO-containing composition having high reactivity with carbon dioxide can be suitably prepared.

[0058] (carbonation process) In the carbonation step, the CaO-containing composition from the preparation step is brought into contact with carbon dioxide (hereinafter also referred to as "carbon dioxide gas") to form a calcium carbonate compound. Although the carbonation method is not particularly limited, a typical preferred method is a carbon dioxide gas method in which carbon dioxide gas is blown into a dispersion of a CaO-containing composition dispersed in water to cause carbonation.

[0059] The solids concentration of the CaO-containing composition in the dispersion may be appropriately set in consideration of carbonation efficiency, but is preferably 10 g / L or more and 500 g / L or less, more preferably 20 g / L or more and 400 g / L or less, and even more preferably 30 g / L or more and 350 g / L or less.

[0060] When the grinding step is carried out dry, the resulting CaO-containing composition may be dispersed in water to have a concentration within the above range. When the grinding step is carried out in a wet manner, water may be added or removed so that the concentration of the resulting suspension of the CaO-containing composition falls within the above concentration range.

[0061] The carbon dioxide used in the carbonation step is preferably carbon dioxide (carbon dioxide gas) emitted from a combustion engine. The carbon dioxide gas used in the carbon dioxide gas method can be a flue gas from a lime calciner installed near a calcium carbonate compound production plant, etc., or a carbon dioxide-containing exhaust gas emitted from a combustion engine such as a boiler or a waste incinerator. This makes it possible to reuse carbon dioxide generated secondarily in industrial processes, thereby contributing to a reduction in carbon dioxide emissions throughout the entire industrial process.

[0062] From the viewpoint of carbonation efficiency, the concentration of carbon dioxide in the carbonation step is preferably 1% by volume or more and 50% by volume or less, more preferably 3% by volume or more and 40% by volume or less, and even more preferably 5% by volume or more and 30% by volume or less.

[0063] From the viewpoint of carbonation efficiency, the temperature in the carbonation step (the temperature of the dispersion liquid) is preferably 5°C or higher and 95°C or lower, more preferably 15°C or higher and 85°C or lower, and even more preferably 25°C or higher and 75°C or lower.

[0064] From the viewpoint of carbonation efficiency and production capacity, the flow rate of the carbon dioxide gas is preferably 10 L / min or more and 200 L / min or less, more preferably 20 L / min or more and 180 L / min or less, and even more preferably 30 L / min or more and 150 L / min or less, per 10 kg of the charged raw material CaO.

[0065] In the carbonation step, stirring is preferably carried out in conjunction with blowing in carbon dioxide gas. When stirring is carried out using a stirring blade, the rotation speed is preferably 100 rpm or more and 600 rpm or less, more preferably 150 rpm or more and 550 rpm or less, and even more preferably 200 rpm or more and 500 rpm or less.

[0066] The carbonation reaction time may be appropriately set so that the carbonation reaction proceeds sufficiently, taking into consideration the concentration of the CaO-containing composition, the concentration and flow rate of carbon dioxide gas, etc. The carbonation reaction time is not limited, but is preferably 0.5 hours or more and 20 hours or less, more preferably 1 hour or more and 18 hours or less, and even more preferably 2 hours or more and 15 hours or less.

[0067] In addition to the carbon dioxide gas method, a solution method is also suitable in which an alkali (NaOH, amine, etc.) is reacted with CO2 to produce Na2CO3 or an amine carbonate, which is then reacted with CaO to produce CaCO3.

[0068] By going through the above steps, a calcium-based carbonate compound can be produced as a carbonate of the CaO-containing composition. The resulting calcium-based carbonate compound may be filtered and dried to form a powder, or may be used as a calcium-based carbonate compound source in the form of a slurry or cake without being filtered and dried.

[0069] <Calcium carbonate compounds> The calcium carbonate compound is preferably a carbonate of the CaO-containing composition. Use of the carbonate of the CaO-containing composition can contribute to the reduction and effective use of waste and the reduction of carbon dioxide emissions.

[0070] The calcium carbonate compound preferably has an SiO2 content of 5% by mass or more and 50% by mass or less, an Al2O3 content of 1% by mass or more and 20% by mass or less, and an Fe2O3 content of 0.5% by mass or more and 15% by mass or less, and an average particle size measured by laser diffraction method of 1 μm or more and 50 μm or less.

[0071] The calcium carbonate compound preferably has an SiO content of 5% by mass to 50% by mass, more preferably 8% by mass to 48% by mass, and even more preferably 10% by mass to 45% by mass, which can improve the strength of the inorganic molded body containing the calcium carbonate compound.

[0072] The calcium carbonate compound preferably contains Al2O3 at a content of 1% by mass to 20% by mass, more preferably 2% by mass to 18% by mass, and even more preferably 3% by mass to 15% by mass, thereby improving the strength of the inorganic molded body containing the calcium carbonate compound.

[0073] The calcium carbonate compound preferably contains Fe2O3 at a content of 0.5 to 15% by mass, more preferably 1 to 12% by mass, and even more preferably 1.5 to 10% by mass, which can improve the strength of the inorganic molded body containing the calcium carbonate compound.

[0074] The calcium carbonate compound has an average particle size, as measured by the laser diffraction method, of preferably 1 μm to 50 μm, more preferably 1.5 μm to 45 μm, even more preferably 2 μm to 40 μm, and particularly preferably 2.5 μm to 35 μm, which can improve the physical properties of the object to which the calcium carbonate compound is applied (for example, the strength and fire resistance of the inorganic molded body).

[0075] The calcium carbonate compound preferably has an SO content of 0.5% by mass to 10% by mass, more preferably 0.8% by mass to 8% by mass, and even more preferably 1% by mass to 6% by mass, which makes it easier to control the curing time of the inorganic molded body containing the calcium carbonate compound, and allows for the production of an inorganic molded body with high strength.

[0076] The calcium carbonate compound has a BET specific surface area of ​​5 m 2 / g or more 200m 2 / g or less, and 2 / g or more 150m 2 / g or less is more preferable, and 10m 2 / g or more 100m 2 / g or less, it is more preferable that the calcium carbonate compound is used in an amount of 1000 to 15000 kJ / g. This makes it possible to improve the physical properties of the object to which the calcium carbonate compound is applied.

[0077] The CaO content in the calcium carbonate compound is preferably 5% by mass or more and 55% by mass or less, more preferably 10% by mass or more and 50% by mass or less, and even more preferably 15% by mass or more and 45% by mass or less.

[0078] The CO2 content in the calcium carbonate compound is preferably 5% by mass or more and 44% by mass or less, more preferably 10% by mass or more and 40% by mass or less, and even more preferably 15% by mass or more and 36% by mass or less. CO2 is mainly derived from calcium carbonate. By setting this value within the above range, the physical properties of the object to which the calcium carbonate compound is applied (for example, fire resistance when applied to an inorganic molded body) can be improved. The CO2 content in the calcium carbonate compound indicates the total content of CO2 in the CaO-containing composition and newly fixed CO2.

[0079] The CO2 fixation rate in the calcium carbonate compound is preferably as high as possible from an environmental perspective, and is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. The CO2 fixation rate in the calcium carbonate compound is a value obtained by subtracting the CO2 content in the CaO-containing composition from the CO2 content in the calcium carbonate compound.

[0080] The higher the production rate of calcium carbonate compounds that contribute to the fixation of carbon dioxide, the better, but it is preferably 15% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more.

[0081] The calcium carbonate compound preferably contains calcite, which is based on the crystalline structure of calcium carbonate and has a small particle size (about 10 μm) and good dispersibility, thereby improving the strength of the inorganic molded body containing the calcium carbonate compound.

[0082] The calcium carbonate compound of the present invention is preferably used for inorganic molded bodies. Since the calcium carbonate compound contains SiO2 and other components that contribute to hardening, it can be used for applications such as the inorganic molded bodies, making it useful.

[0083] The present invention also provides a calcium carbonate compound containing CaCO3, which has an SiO2 content of 5% by mass or more and 50% by mass or less, an Al2O3 content of 1% by mass or more and 20% by mass or less, and an Fe2O3 content of 0.5% by mass or more and 15% by mass or less, and has an average particle diameter of 1 μm or more and 50 μm or less as measured by a laser diffraction method. system Concerning carbonate compounds.

[0084] The present invention also relates to a calcium carbonate compound containing CaCO3, which has an SiO2 content of 5% by mass or more and 50% by mass or less, an Al2O3 content of 1% by mass or more and 20% by mass or less, and an Fe2O3 content of 0.5% by mass or more and 15% by mass or less, and has an average particle size of 1 μm or more and 50 μm or less as measured by a laser diffraction method.

[0085] The calcium carbonate compound preferably has a higher CaCO3 content from an environmental perspective, preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more. Furthermore, from the viewpoint of maintaining the strength of the inorganic molded body containing the calcium carbonate compound, the CaCO3 content in the calcium carbonate compound may be less than 80% by mass, less than 75% by mass, or even less than 70% by mass.

[0086] The calcium carbonate compound of the present invention is preferably obtained using carbon dioxide (carbon dioxide gas) emitted from a combustion engine. As described in detail in the carbonation step of the method for producing the calcium carbonate compound, the carbon dioxide (carbon dioxide gas) used in the carbon dioxide gas method can be the flue gas of a lime kiln installed near a calcium carbonate compound production plant, or a carbon dioxide-containing exhaust gas emitted from a combustion engine such as a boiler or a waste incinerator. This allows carbon dioxide generated secondarily in industrial processes to be reused, contributing to a reduction in carbon dioxide emissions throughout the entire industrial process.

[0087] <Applications of calcium carbonate compounds> The calcium carbonate compound is suitable for use in any application, including, but not limited to, for example, as a high-performance additive for inorganic molded bodies, such as building materials, a filler for resins, etc. Hereinafter, an embodiment in which the calcium carbonate compound is used in an inorganic molded body will be described.

[0088] <Inorganic molded body> The present invention relates to an inorganic formed body containing the calcium carbonate compound. The inorganic formed body containing the calcium carbonate compound is a mixture of calcium carbonate and SiO2 and other impurities, and is therefore useful in that it improves compressive strength and fire resistance.

[0089] The inorganic molded body is not particularly limited, and typical examples include molded boards for building materials, concrete structures (concrete molded bodies), etc. Applicable compositions and the like will be described in detail below depending on the application.

[0090] The inorganic molded bodies are molded bodies mostly composed of inorganic substances such as hydraulic materials and siliceous materials, and have properties such as fire resistance, light weight, high strength, and workability, and are therefore widely used for exterior wall materials, roof underlayment materials, eaves ceiling materials, etc. for houses, etc. They are also widely used for foundations, walls, pillars, floors, etc. of buildings where strength and fire resistance are required. By using a specific calcium-based carbonate compound in such a wide-ranging inorganic molded body, it is possible to reduce the environmental load throughout the entire industrial process.

[0091] (molded board for building materials) The molding board preferably contains a hydraulic material, a siliceous material, a reinforcing fiber material, and a calcium carbonate compound.

[0092] (hydraulic material) Examples of the hydraulic material include cementitious materials, gypsum, lime, slag, etc. Examples of the cementitious material include commonly used cements, such as ordinary Portland cement, high-early-strength cement, moderate-heat cement, fly ash cement, blast furnace slag cement, and alumina cement. Examples of gypsum include anhydrous gypsum, hemihydrate gypsum, and dihydrate gypsum. Examples of slag include blast furnace slag and converter slag. These hydraulic materials can be used alone or in combination of two or more.

[0093] The content of the hydraulic material is preferably 5% by mass or more and 45% by mass or less, more preferably 8% by mass or more and 42% by mass or less, and even more preferably 10% by mass or more and 40% by mass or less, based on the total amount of materials constituting the molded board. By setting the content of the hydraulic material within the above range, it is possible to improve the physical properties of the molded board, such as bending strength and peel strength, and to prevent the molded board from becoming too high in bulk density, thereby improving workability during construction.

[0094] (siliceous material) Examples of the siliceous material include materials containing a large amount of SiO, such as silica sand, silica powder, silica fume, fly ash, diatomaceous earth, layered silicates (e.g., mica, talc, kaolin, bentonite), perlite, wollastonite, and lightweight aggregates (e.g., fly ash balloons, perlite, shirasu balloons, glass foam, etc.). These siliceous materials can be used alone or in combination of two or more. Talc, mica, and wollastonite can also be used as reinforcing fiber materials, which will be described later.

[0095] The content of the siliceous material is preferably 10% by mass or more and 55% by mass or less, more preferably 12% by mass or more and 50% by mass or less, and even more preferably 15% by mass or more and 45% by mass or less, based on the total amount of materials constituting the molded board. If the content of the siliceous material is within the above range, it becomes possible to set the bending strength, bulk specific gravity, water absorption rate, dimensional stability, etc. of the molded board within the desired range. Incidentally, as the siliceous material, perlite, fly ash balloons, shirasu balloons, etc., having a unit volume mass of 0.5 g / cm are preferred. 3 When mixing the following lightweight aggregates, it is preferable to use other siliceous materials in combination so that the content of lightweight aggregate is 20 mass% or less, based on the total amount of materials constituting the molded board, in order to prevent the bulk density from becoming too light and weakening strength such as bending strength and peel strength.

[0096] (reinforcing fiber material) Examples of the reinforcing fiber material that can be used include pulps such as softwood pulp, hardwood pulp, fibrillated pulps thereof, and pulp obtained by defibrating waste paper, organic reinforcing fiber materials such as vinylon fiber, acrylonitrile fiber, and polypropylene fiber, and inorganic reinforcing fiber materials such as rock wool and glass fiber. These reinforcing fiber materials can be used alone or in combination of two or more.

[0097] To improve the strength and toughness of the molded board, the content of the reinforcing fiber material is preferably 2% by mass or more and 30% by mass or less, more preferably 3% by mass or more and 26% by mass or less, and even more preferably 4% by mass or more and 22% by mass or less, based on the total amount of materials constituting the molded board. By setting the content of the reinforcing fiber material within the above range, it is possible to achieve a sufficient reinforcing effect while suppressing the protrusion of fibers from the surface of the molded board, thereby improving smoothness. When an inorganic reinforcing fiber material having an average fiber length of 1 mm or more and 50 mm or less is blended as the reinforcing fiber material, it is preferable to use another reinforcing fiber material in combination so that the content is 10% by mass or less, based on the total amount of materials constituting the molded board, in order to improve the smoothness of the molded board.

[0098] (Calcium carbonate compounds) As the calcium carbonate compound, the calcium carbonate compounds described above can be suitably used.

[0099] The content of the calcium carbonate compound is preferably 5% by mass or more and 60% by mass or less, more preferably 8% by mass or more and 55% by mass or less, and even more preferably 12% by mass or more and 50% by mass or less, based on the total amount of materials constituting the molded board. By blending a calcium carbonate compound with low thermal conductivity at a content within the above range, the strength and fire resistance of the molded board can be improved.

[0100] (optional ingredient) In addition to the above materials, the molded board can be blended with various materials depending on the purpose, such as hollow resin bodies, wood chips, wood flour, resin powder, antifoaming agents, flocculants, water repellents, thickeners (methyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, etc.), dispersants, etc. In addition, recycled materials such as crushed scraps generated during the processing of the molded board can be added as appropriate.

[0101] The bulk density of the molded plate is 0.7 g / cm 3 It is preferable that the concentration is 0.8 g / cm or more. 3More preferably, it is 0.9 g / cm or more. 3 It is more preferable that the above conditions are satisfied. This can improve the strength of the molded plate.

[0102] (Method of manufacturing molded plate) The method for producing the molded plate is not particularly limited, and commonly used methods such as papermaking, extrusion molding, flow-on molding, casting, and press (compression) molding can be used. The molded plate can be obtained by subjecting a green sheet molded by these methods to press dehydration or patterning by embossing or the like, followed by curing at room temperature, steam curing, autoclave curing, or the like. The molded plate may then be dried and, if necessary, shaped or painted.

[0103] (Uses of molded boards) The uses of the molded board are not particularly limited, and it can be suitably used as a performance maintaining material for wall construction, flooring, roofing, various boards, exterior decorative members, interior and exterior finishing materials such as fittings, sealing materials, heat insulating materials, sound absorbing materials, waterproofing materials, etc. The molded board is preferably a cementitious molded board containing a cementitious material, and more preferably a calcium silicate molded body.

[0104] (concrete structures) The concrete structure is composed of a hardened hydraulic composition. The hydraulic composition is made of a powder containing a calcium carbonate compound and at least one of blast furnace slag, expansive agent, slaked lime, quicklime, fly ash, and Portland cement. The calcium carbonate compound may be any of the calcium carbonate compounds described above.

[0105] In addition to the hydraulic composition, aggregates such as sand and gravel, chemicals such as chemical admixtures for concrete, and fiber materials made of metals or polymeric materials may be blended to form a hydraulic composition mixture.

[0106] The hardened product of the hydraulic composition is obtained by hardening a paste obtained by kneading the hydraulic composition with water. The hardened product of the hydraulic composition mixture is obtained by hardening a mixture (equivalent to fresh mortar or fresh concrete) obtained by kneading the hydraulic composition mixture with water, and corresponds to mortar or concrete.

[0107] The ratio of the calcium carbonate compound in the powder (the ratio of the calcium carbonate compound to the cement) is preferably 1% by mass or more and 60% by mass or more, more preferably 3% by mass or more and 50% by mass or less, and even more preferably 5% by mass or more and 40% by mass or less.

[0108] It is desirable to use ground granulated blast furnace slag used in JIS (Japanese Industrial Standards) R5211 "blast furnace cement" or ground granulated blast furnace slag conforming to JIS A6206 "blast furnace slag for concrete" as the blast furnace slag. The blast furnace slag preferably has a specific surface area of ​​2000 cm 2 / g or more 10000cm 2 / g or less, more preferably 3500 cm 2 / g or more 7000cm 2 Use one that is equal to or less than / g.

[0109] The expansive material may be, for example, an expansive material specified in JIS A6202 “Expansive material for concrete.” The expansive material is preferably added in an amount of 2 to 9 mass % based on the total amount of the hydraulic composition.

[0110] The slaked lime may be, for example, that specified in JIS R9001 "Industrial Lime." Furthermore, since quicklime becomes slaked lime when it comes into contact with water, quicklime specified in JIS R9001 "Industrial Lime" may be used instead of slaked lime. In this case, it is advisable to adjust the amount of water required to convert quicklime into slaked lime. The fly ash may be, for example, that conforming to JIS A6201 "Fly Ash for Concrete."

[0111] As the Portland cement, ordinary Portland cement is used, but other types of Portland cement such as high-early-strength Portland cement, ultra-high-early-strength Portland cement, moderate-heat Portland cement, low-heat Portland cement, and sulfate-resistant Portland cement, as specified in JIS R5210 "Portland cement," and JIS R5214 "Ecocement" can also be used.

[0112] When the hydraulic composition contains Portland cement, the proportion of Portland cement in the powder other than the calcium carbonate compound is 70% by mass or less, and preferably 30% by mass or less.

[0113] Furthermore, when Portland cement and blast furnace slag or fly ash are used, the components may be pre-mixed, for example, JIS R5211 "blast furnace cement" or, for example, JIS R5213 "fly ash cement," and the pre-mixed components may be used alone or in combination.

[0114] Since the calcium carbonate compound having the above characteristics is used, the hydraulic composition and the hydraulic composition mixture exhibit good fluidity, and the hardened concrete produced from the composition can exhibit excellent compressive strength.

[0115] The density of the concrete structure is 0.7 g / cm 3 It is preferable that the concentration is 0.8 g / cm or more. 3 More preferably, it is 0.9 g / cm or more. 3 It is more preferable that the above-mentioned condition is satisfied. This improves the strength of the concrete structure.

[0116] <Method for increasing the CO2 fixation rate of inorganic molded bodies> The present invention relates to a method for increasing the CO2 fixation rate of the inorganic molded body by using ultrafinely pulverized water granulated slag. The CaO-containing composition for producing the calcium-based carbonate compound obtained by using the ultrafine pulverized product of the water-quenched slag has a large specific surface area, so the contact area with carbon dioxide is wide, and the immobilization rate of carbon dioxide can be improved. This is useful for improving the fire resistance of the inorganic molded body using the same. Incidentally, the ultrafine pulverized product refers to water-quenched slag (for example, 1.2 mm blast furnace slag fine aggregate described later) pulverized using a ball mill or the like to a BET specific surface area of 50 m 2 / g or more and an average particle diameter of 5 μm or less.

Examples

[0117] Hereinafter, the present invention will be described in detail using examples. However, the present invention is not limited to the following examples as long as the gist thereof is not exceeded. The measurement and evaluation of physical properties and the like were carried out as shown below.

[0118] <Evaluation of CaO-containing composition and calcium-based carbonate compound> For the CaO-containing composition and the calcium-based carbonate compound obtained in the examples and comparative examples (hereinafter, both may be referred to as "samples" in some cases), the following analysis and evaluation were performed. In any case of the dry product, wet product and suspension of the sample, about 50 g was collected in a petri dish with a capacity of 200 mL in advance and dried at 110 ° C for 12 hours and used for analysis and evaluation. The analysis and evaluation results of the CaO-containing composition are shown in Table 1, and the analysis and evaluation results of the calcium-based carbonate compound are shown in Table 2. In addition, for calcium-based carbonate compounds 1 to 3 and calcium-based carbonate compound 6 (Examples 2-1 to Examples 2-3 and Comparative Example 2-1), SEM photographs shown in FIGS. 2 to 5 were taken.

[0119] (Loss on ignition) Approximately 2 g of the sample was put into a porcelain crucible whose mass had been measured in advance to a constant weight, and the total mass was precisely weighed. This was heated in an electric furnace at 900 ° C for 3 hours or more. It was cooled to room temperature in a desiccator and precisely weighed, and the difference in mass before and after heating was obtained as the loss on ignition. Based on the following formula, the loss on ignition (mass basis) was determined. [Number] (In the formula, L is the loss on ignition (mass %), D is the weight loss (g), and S is the weight of the sample (g).)

[0120] (Contents of CaO, SiO2, Fe2O3, Al2O3, and SO3) [ICP-AES method] Weighed 0.2 g of the sample into a platinum crucible, added 0.5 g of boric acid and 2.0 g of potassium carbonate, and melted it in an electric furnace at 900 °C for 30 minutes. After cooling, put the platinum crucible into a 200 mL beaker, added 50 mL of hydrochloric acid (a solution prepared by mixing concentrated hydrochloric acid and water in a volume ratio of 1:1) with a dispenser, heated and dissolved it. After cooling, transferred it to a 250 mL volumetric flask, added water up to 250 mL to make it up to volume. From this, 20 mL was taken and transferred to a 50 mL volumetric flask, and water was added up to 50 mL to obtain a test solution for measurement. On the other hand, 20 mL was taken from the above-mentioned 250 mL made-up aqueous solution and transferred to a 50 mL volumetric flask, and standard solutions of each element (Ca, Si, Fe, Al, and S) were arbitrarily added to prepare calibration standard solutions with different concentrations. Note that the standard solutions of each element used were 1000 ppm standard solutions for atomic absorption (commercially available).

[0121] Set the calibration standard solutions with different concentrations to which each element was added and the test solution for measurement in the autosampler of an inductively coupled plasma optical emission spectrometry (ICP-AES) apparatus (manufactured by Hitachi High-Tech Science Corporation, "SPECTROBLUE FMS36 type"), and measured the amounts (ppm) of Ca, Si, Fe, Al, and S under the following conditions. [Measurement conditions] RF output: 1.4 kW Carrier gas (humidified) flow rate: 0.9 L / min Plasma gas flow rate: 13.0 L / min Auxiliary gas flow rate; 1.0 L / min Liquidity: Aqueous solution Number of integrations: 3 times Sample order: For each sample Measurement method: Standard addition method Weighting of calibration curve: None Measurement wavelength: Ca: 317.933 nm Si: 251.612 nm Fe: 238.204 nm Al: 167.078 nm S: 182.034 nm Finally, the content (mass%) of each element was determined from the determined amount of each element, and the contents (mass%) of CaO, SiO2, Fe2O3, Al2O3, and SO3 were calculated in terms of their oxides.

[0122] (CO2 content) The reagents used in the measurement were prepared as follows. 1 / 10N barium hydroxide solution: 15.8 g of barium hydroxide (octahydrate) was dissolved in ultrapure water to a total volume of 1000 mL. After sealing and shaking well, the container was left to stand for at least one day, and the supernatant was taken and used as the solution. Sulfuric acid: A solution was prepared by mixing concentrated sulfuric acid and water in a 1:1 volume ratio. 1 / 10N hydrochloric acid standard solution: Prepared by diluting 1N hydrochloric acid 10 times. PP indicator: Dissolve 1 g of phenolphthalein in ethanol to make a total of 100 mL.

[0123] Figure 1 is a schematic diagram showing a measuring device for measuring the CO2 content. Gas was circulated inside the measuring device by a circulation pump, and an airtight state was maintained during circulation. In the figure, arrows indicate the direction of gas flow.

[0124] Using the measurement apparatus shown in Figure 1, the CO2 content (mass%) was determined using the following procedure. 20.0 mL of 1 / 10 N barium hydroxide solution was placed in a 100 mL medium bottle, two drops of PP indicator were added, and the bottle was sealed. Separately, 0.1 g of sample was placed in a 500 mL medium bottle, and water was added to bring the total volume to 200 mL. 10 mL of sulfuric acid was added to the dish using a measuring cup, the bottle was immediately sealed, and the circulation pump was started. After operating for more than 90 minutes, the 100 mL medium bottle was removed from the apparatus and titrated directly with 1 / 10 N hydrochloric acid standard solution. The same procedure was repeated without adding the sample to the 500 mL medium bottle as a control. The CO2 content (mass%) was calculated using the following formula.

number

[0125] (Free CaO content) The free CaO content Z (mass%) was calculated using the data of the ignition loss, CaO content, SO3 content, and CO2 content obtained above, according to the following formula, where "%" represents "mass%."

number

[0126] (BET specific surface area) The sample powder was pretreated in an 8-well preheat unit (MOUNTECH) at approximately 130°C for approximately 30 minutes under a nitrogen gas atmosphere. The BET specific surface area (m) was measured by nitrogen gas adsorption using a Macsorb HM Model-1208 (MOUNTECH) BET specific surface area measuring device. 2 / g) was measured.

[0127] (Average particle size by laser diffraction method) 50 mL of ethanol was placed in a 100 mL beaker, and approximately 0.2 g of the sample powder was placed in the 100 mL beaker. The mixture was subjected to ultrasonic treatment (UD-201, manufactured by Tomy Seiko Co., Ltd.) for 3 minutes to prepare a dispersion. The volumetric D of this dispersion was measured using a laser diffraction particle size distribution analyzer (Microtrac HRA Model 9320-X100, manufactured by Nikkiso Co., Ltd.). 50 The value was measured as the average particle size (μm).

[0128] (Crystalline identification by XRD) The sample powder was pressed onto a designated sample stage with a spatula, and then measured using an XRD device (MiniFlex600-C, manufactured by Rigaku Corporation) to identify the material as a crystalline substance. It was confirmed that all of the calcium carbonate compounds obtained, which will be described later, contained calcite crystals.

[0129] (CO2 fixation rate in calcium carbonate compounds) The CO2 fixation rate D (mass%) in the calcium carbonate compound was calculated using the following formula.

number

[0130] (Production rate of calcium carbonate compounds that contributed to CO2 fixation) The production rate E (mass%) of calcium carbonate compounds that contributed to CO2 fixation was calculated using the following formula. [Number] (In the formula, d is the CO2 content rate (mass %) in the calcium-based carbonate compound. e is the CO2 content rate (mass %) in the CaO-containing composition.)

[0131] (Content rate of CaCO3 in the calcium-based carbonate compound) The content rate (mass %) of CaCO3 in the calcium-based carbonate compound was determined from the following formula. The content rate of CaCO3 in the calcium-based carbonate compound indicates the total content rate of CaCO3 derived from the raw material and CaCO3 newly fixed with CO2. [Number] (In the formula, d is the CO2 content rate (mass %) in the calcium-based carbonate compound.)

[0132] (Scanning electron microscope observation) A double-sided tape was attached to the aluminum sample stage, and the sample powder was applied thereon by tracing it with the spatula blade. After platinum evaporation, SEM photographs at 1000 times and 5000 times were taken of the particle images of the sample powder using a scanning electron microscope (FE-SEM: S-4700 manufactured by Hitachi, Ltd.). For the obtained calcium-based carbonate compounds 1 to 3 and 6, SEM photographs shown in FIGS. 2 to 5 were taken to determine the particle size.

[0133] <Preparation of CaO-containing composition and production of calcium-based carbonate compound> (Example 1-1 and Example 2-1) An 8-L stainless steel container with a baffle was filled with 6 L of water, and 1.0 kg of a CaO-containing composition (CaO-containing composition 1) was added to the container under stirring. The temperature was then raised to 40 °C, and the mixture was stirred at 350 rpm using a stirrer equipped with a single turbine blade. A flue gas extraction pipe was connected to the exhaust outlet of an LNG-fueled steam production boiler, and the flue gas was drawn in using a test blower. Measurements using a CO2 concentration meter (XP-3140, New Cosmos Electric Co., Ltd.) revealed a CO2 concentration of 10% by volume. The flue gas was introduced into the 8-L stainless steel container at a rate of 3.3 L / min using a test blower, and the mixture was allowed to react for 10 hours. Next, the mixture was filtered, and the filtered wet matter was dried at 110° C. for 12 hours and pulverized to obtain a sample powder of calcium carbonate compound 1 (see FIG. 2). The CaO-containing composition used for analysis was dried at 110° C. for 12 hours (hereinafter, the same applies to calcium carbonate compounds 2 to 5).

[0134] (Examples 1-2 and 2-2) A sample powder of calcium-based carbonate compound 2 was obtained by the same procedure as calcium-based carbonate compound 1, except that the CaO-containing composition used was a wet papermaking sludge calcined ash (manufactured by Marusumi Paper Co., Ltd., sample name: CY ash, average particle size 20 μm) dry-ground using a Wonder Crusher (CaO-containing composition 2) (see Figure 3).

[0135] (Examples 1-3 and 2-3) An aqueous sodium carbonate solution was prepared by adding 894 g of sodium carbonate reagent (manufactured by Wako Pure Chemical Industries, Ltd.: purity 99.8%) to a 20 L SUS container equipped with a baffle and containing 18 L of water while stirring. Separately, 10 L of water and 1.7 kg of granulated slag (1.2 mm blast furnace slag fine aggregate (BFS1.2) according to JIS A 5011-1:2018 "Slag aggregate for concrete - Part 1") were placed in a 20 L pot mill filled with 5 kg of 8 mm diameter zirconia balls and wet-ground at 90 rpm for 24 hours to prepare CaO-containing composition 3. The ground slurry was removed from the pot mill, and 6 L of this ground slurry was placed in a 30 L polyethylene container. 18 L of the aforementioned sodium carbonate aqueous solution was added all at once while stirring at 25 °C. Stirring was continued for approximately 30 minutes to allow the reaction to proceed. The mixture was then filtered, washed with approximately five times the amount of water relative to the solid content, dried at 110 °C for 24 hours, and ground to obtain a sample powder of calcium carbonate compound 3 (see Figure 4).

[0136] (Examples 1-4 and 2-4) A sample powder of calcium carbonate compound 4 was obtained by the same procedure as for calcium carbonate compound 1, except that a CaO-containing composition (CaO-containing composition 4) was prepared by dry-pulverizing cement sludge (manufactured by Taisei Namakon Co., Ltd., average particle size 15 μm) using a Wonder Crusher.

[0137] (Examples 1-5 and 2-5) A CaO-containing composition was prepared by roughly crushing a cement-based solidified material (manufactured by Yonezawa Kogyo Co., Ltd., product name: Concrete Block Type A) with a hammer and passing it through a 4 mm mesh sieve. The under-4 mm particles were dry-crushed with a Wonder Crusher to prepare CaO-containing composition 5. A sample powder of calcium carbonate compound 5 was obtained by the same procedure as calcium carbonate compound 1.

[0138] (Comparative Example 1-1 and Comparative Example 2-1) A sample powder of calcium-based carbonate compound 6 was obtained by the same procedure as for calcium-based carbonate compound 3, except that non-wet-ground granulated slag (1.2 mm blast furnace slag fine aggregate (BFS1.2) according to JIS A 5011-1:2018 "Slag aggregate for concrete - Part 1") (CaO-containing composition 6) was used as the CaO-containing composition (see Figure 5). Note that the average particle size of the sample powder of calcium-based carbonate compound 6 exceeded the measurement limit (1000 μm) of the measuring device (laser diffraction particle size distribution analyzer) used in measuring the average particle size by the laser diffraction method, and therefore could not be evaluated.

[0139] (Production of molded body of cement composition (concrete structure)) The calcium carbonate compounds of the types and amounts shown in Table 3 were added to 1600 g of water and stirred manually with a stirring rod for approximately 30 seconds. The mixture was then stirred at 400 rpm using a mixer (Yamato Scientific Co., Ltd., "Labostirrer (LR500B)") to obtain a mixture. Cement (Tokuyama Corporation, "Normal Portland Cement (N)") was added to the mixture in the amounts shown in the table over approximately 20 seconds and mixed with the mixer for 3 minutes. After stopping the stirring and allowing the mixture to stand for 3 minutes, the mixture was manually stirred 10 times with a stirring rod (AS ONE Corporation, "POM Stirring Rod φ10 × 300 mm") to produce the cement milk. To maintain a certain degree of fluidity during mixing, a dispersant (Level Flow EX) was added in small amounts during mixing after the cement was added. The final dispersant addition amounts were as shown in the table. In addition, in the blank (Comparative Example 3-1), 400 g of fine aggregate (crushed sand; under 5 mm) was added instead of the calcium carbonate compound. 400 mL of the prepared cement milk was poured into a cylindrical polyethylene bag (diameter approximately 50 mm x length approximately 550 mm x thickness approximately 0.05 mm) up to the marked line. After injecting as much air as possible and sealing the bag, the bag was hung in an incubator set at 22°C. The bag was left hanging in the incubator for 28 days to harden the contents, producing a total of three cement composition molded bodies (concrete structures). The obtained cement composition molded bodies were cylindrical, with a diameter of approximately 5 cm and a length of approximately 20 cm.

[0140] <Evaluation of cement composition molded bodies (concrete structures)> The following evaluations were carried out on the molded articles (concrete structures) of the cement compositions produced in Examples 3-1 to 3-6, Comparative Examples 3-1 and 3-2. The results are shown in Table 3.

[0141] (CO2 fixation rate in cement composition) The CO2 fixation rate H (mass%) in the cement composition was calculated using the following formula.

number

[0142] (density) The density (g / cm) of the molded body (concrete structure) of the obtained cement composition was measured in accordance with JIS A 5430:2008 (apparent density test). 3 ) was measured.

[0143] (Compression strength test) The compressive strength (N / mm) of the molded body (concrete structure) of the obtained cement composition was measured in accordance with JIS A 1108:2018 (Method of compressive test of concrete). 2 ) was measured. The higher the compressive strength of the molded body (concrete structure) of the cement composition, the better. 2 More than 34N / mm is preferable. 2 More preferably, 36N / mm 2 The above is more preferable.

[0144] <Manufacturing of inorganic molded bodies (building materials)> An inorganic molded body (building material) was produced by a papermaking method according to the following procedure: The amounts of the components used are all expressed in "parts by mass" unless otherwise specified.

[0145] (Example 4-1 and Comparative Example 4-1) The materials shown in Table 4 were charged into a plastic container and stirred to obtain a raw material slurry. In Example 4-1, calcium carbonate compound 1 was used as the calcium carbonate compound (no calcium carbonate compound was used in Comparative Example 4-1). The raw material slurry was divided and poured into a filter lined with felt, and a laminate (long side 28 mm x short side 24 mm x thickness 14 mm) was produced while suction filtering was performed using a vacuum pump. The laminate was removed from the filter and subjected to dehydration pressing. The thickness after pressing was 13 mm. After autoclave curing (curing pressure (gauge pressure) 9 kgf; curing time 12 hours), the pressed body was dried in a dryer (105°C) for 24 hours. Both sides were sanded with a sander to adjust the thickness to 12 mm, and an inorganic molded body was obtained.

[0146] <Evaluation of inorganic molded bodies> In the examples and comparative examples, the inorganic molded articles produced by the above method (papermaking method) were evaluated as follows. The results are shown in Table 4.

[0147] (CO2 fixation rate in inorganic molded bodies (building materials)) The CO2 fixation rate I (mass%) in the inorganic molded body (building material) was calculated using the following formula.

number

[0148] (bulk density) The bulk density of the inorganic molded body (building material) was measured in accordance with JIS A 5430.

[0149] (heating test) The heating test was carried out using the following equipment and procedure. Figure 6 is a partial perspective view that shows a schematic diagram of the heating tester. As shown in the figure, an electric heater was used as the heat source, and fireproof material was installed between the test specimen and the heat source to stabilize the temperature at around 900°C, and a thermocouple was used to measure the temperature on the backside of the test specimen. Specifically, the electric heater (1.2 kW heater) was fixed as the heat source equipment so that the distance between the heating surface of the test specimen and the heat source was approximately 70 mm.

[0150] The test procedure was as follows. (1) A scrap board was placed and preheating was carried out up to 902°C, after which heating was stopped temporarily. (2) The specimen was inserted after the heated surface had cooled to below 200°C. (3) A thermocouple was placed in the center of the back surface (top surface in the figure) of the test specimen, and a calcium silicate plate (approximately 30 mm x 70 mm) and a weight were placed on top and fixed in place. (4) Heating was started, and the temperature on the heating surface and back surface was recorded with a data logger after the specified time (45 minutes). During this time, the temperature setting of the electric heater was 902°C on the heating surface side, and the temperature was controlled with a temperature controller with a lower limit of 900°C. The data logger also measured the temperature every 10 seconds, and the data was recorded at this interval. (5) After the test was completed, the specimen was removed and the following items were measured (each item was also measured before the test): Dimensions: The length and width of the back surface and heating surface were measured with a vernier caliper. The area of ​​the heating surface (mm 2 ) was calculated, and the heated surface shrinkage (%) was determined based on the following formula. The heated surface shrinkage (%) is preferably 3% or less. The rise in the back surface temperature before and after the test is preferably 450°C or less.

number

[0151] [Table 1]

[0152] [Table 2]

[0153] [Table 3]

[0154] [Table 4]

[0155] From the results in Tables 1 and 2 above, the average particle diameters of the CaO-containing compositions of the Examples were all smaller than those of the Comparative Examples, and the CO2 fixation rate in the calcium carbonate compounds, the production rate of the calcium carbonate compounds that contributed to the CO2 fixation, and the CaCO3 content in the calcium carbonate compounds were all higher than those of the Comparative Examples.

[0156] From the results in Table 3 above, it was confirmed that the examples using the desired calcium carbonate compound were able to simultaneously satisfy the desired properties of CO2 fixation rate, density, and compressive strength.

[0157] From the results in Table 4 above, it was confirmed that the examples using calcium carbonate compounds were able to simultaneously satisfy the desired properties in the evaluations of CO2 fixation rate, heated surface shrinkage, and back surface temperature rise, compared to the comparative examples.

Claims

1. The content of free CaO is 15% by mass or more and less than 50% by mass, SiO ２ The content of is 5% by mass or more and 50% by mass or less, Al ２ O ３ The content of is 1% by mass or more and 20% by mass or less, Fe ２ O ３ The content of is 0.5% by mass or more and 15% by mass or less, The average particle size measured by a laser diffraction method is 1 μm or more and 50 μm or less, BET specific surface area is 1 m ２ / g or more 100m ２ / g or less of the CaO-containing composition.

2. SO ３ The CaO-containing composition according to claim 1, wherein the content of is 0.8 mass% or more and 10 mass% or less.

3. The CaO-containing composition according to claim 1, which is a pulverized product of a CaO-containing raw material.

4. The CaO-containing composition according to claim 3, wherein the CaO-containing raw material is derived from at least one of paper sludge incineration ash, chicken manure incineration ash, cement sludge, cement sludge incineration ash, and hydrates thereof.

5. The CaO-containing composition according to claim 1, which is for recycling.

6. A preparation step of preparing a CaO-containing composition according to any one of claims 1 to 5; and contacting the CaO-containing composition with carbon dioxide to form a calcium carbonate compound; A method for producing a calcium-based carbonate compound, comprising a carbonation step.

7. In the preparation step of preparing the CaO-containing composition, The CaO-containing composition has a free CaO content of 15% by mass or more and less than 50% by mass, and ２ The content of Al is 5 mass % or more and 50 mass % or less, ２ O ３ The content of is 1 mass % or more and 20 mass % or less, and Fe ２ O ３ The content of the above is 0.5% by mass or more and 15% by mass or less, the average particle size measured by a laser diffraction method is 1 μm or more and 50 μm or less, and the BET specific surface area is 1 m ２ / g or more 100m ２ 7. The method for producing a calcium carbonate compound according to claim 6, wherein the CaO-containing raw material has a CaO content of 0.1g or less and is a pulverized product of a CaO-containing raw material, and the CaO-containing raw material is derived from at least one of incineration ash of paper sludge, incineration ash of chicken manure, cement sludge, incineration ash of cement sludge, and hydrates thereof.

8. 7. The method for producing a calcium-based carbonate compound according to claim 6, wherein the preparation step includes a pulverization step of pulverizing a CaO-containing raw material.

9. 7. The method for producing a calcium carbonate compound according to claim 6, wherein the concentration of carbon dioxide in the carbonation step is 1% by volume or more and 50% by volume or less.

10. 7. The method for producing a calcium carbonate compound according to claim 6, wherein the carbon dioxide used in the carbonation step is carbon dioxide emitted from a combustion engine.

11. The method for producing a calcium carbonate compound according to claim 6, wherein the temperature in the carbonation step is 5°C or higher and 95°C or lower.

12. A calcium carbonate compound, which is a carbonate of the CaO-containing composition according to any one of claims 1 to 5.

13. SiO ２ The content of is 5% by mass or more and 50% by mass or less, Al ２ O ３ The content of is 1% by mass or more and 20% by mass or less, Fe ２ O ３ The content of is 0.5% by mass or more and 15% by mass or less, 13. The calcium carbonate compound according to claim 12, having an average particle size of 1 μm or more and 50 μm or less as measured by a laser diffraction method.

14. SO ３ The calcium carbonate compound according to claim 12, wherein the content of is 0.8 mass % or more and 10 mass % or less.

15. CO ２ The calcium carbonate compound according to claim 12, having a fixation rate of 5% by mass or more.

16. BET specific surface area is 5m ２ / g or more 200m ２ The calcium carbonate compound according to claim 12, wherein the calcium carbonate content is 0.01g or less.

17. 13. The calcium carbonate compound of claim 12, which contains calcite.

18. The calcium carbonate compound according to claim 12, which is for use in inorganic molded bodies.

19. An inorganic formed body comprising the calcium carbonate compound according to claim 12.

20. The inorganic molded product according to claim 19 is produced by using ultrafinely pulverized granulated slag. ２ How to increase fixation rate.

21. CaCO ３ A calcium carbonate compound comprising: SiO ２ The content of is 5% by mass or more and 50% by mass or less, Al ２ O ３ The content of is 1% by mass or more and 20% by mass or less, Fe ２ O ３ The content of is 0.5% by mass or more and 15% by mass or less, The average particle size measured by a laser diffraction method is 1 μm or more and 50 μm or less, BET specific surface area is 5m ２ / g or more 200m ２ / g or less of a calcium carbonate compound.

22. CaCO ３ The calcium carbonate compound according to claim 21, wherein the content of is 10% by mass or more.

23. SO ３ The calcium carbonate compound according to claim 21, wherein the content of is 0.8% by mass or more and 10% by mass or less.

24. CO ２ 22. The calcium carbonate compound according to claim 21, wherein the fixation rate is 5% by mass or more.

25. 22. The calcium carbonate compound of claim 21, which contains calcite.

26. The calcium carbonate compound according to claim 21, which is for use in inorganic molded bodies.

27. An inorganic formed body comprising the calcium carbonate compound according to claim 21.

28. The inorganic molded product according to claim 27, wherein ultrafine pulverized water granulated slag is used. ２ How to increase fixation rate.

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