CaO-CONTAINING COMPOSITION, METHOD FOR PRODUCING CALCIUM-BASED CARBONATE COMPOUND, CALCIUM-BASED CARBONATE COMPOUND, INORGANIC MOLDED BODY, AND METHOD FOR INCREASING CO2 IMMOBILIZATION RATE OF INORGANIC MOLDED BODY

Abstract

Provided are: a CaO-containing composition that can suppress environmental impact and cause a carbonation reaction to progress efficiently; a method for producing a calcium-based carbonate compound in which the CaO-containing composition is used; a calcium-based carbonate compound; an inorganic molded body; and a method for increasing the CO2 immobilization rate of the inorganic molded body. In the CaO-containing composition, the free CaO content is at least 15 mass% to less than 50 mass%, the SiO2 content is 5-50 mass%, the Al2O3 content is 1-20 mass%, the Fe2O3 content is 0.5-15 mass%, and the average particle diameter as obtained by using a laser diffraction method is 1-50 μm.

Description

CaO-containing composition, method for producing calcium-based carbonate compounds, calcium-based carbonate compounds, inorganic molded articles, and method for increasing the CO2 fixation rate of inorganic molded articles.

[0001] The present invention relates to a CaO-containing composition, a method for producing calcium-based carbonate compounds, calcium-based carbonate compounds, an inorganic molded article, and the CO of an inorganic molded article. ２ Regarding methods for increasing the fixation rate.

[0002] In recent years, with growing environmental awareness due to issues such as global warming, and the demand for reducing carbon dioxide emissions into the atmosphere, attempts are being made to reuse by-products and by-generated energy such as waste, exhaust gases including carbon dioxide, and waste heat generated at industrial facilities such as incinerators, steel mills, and cement factories.

[0003] For example, concrete waste is produced in enormous quantities, making its reuse essential from the perspectives of conserving natural resources, protecting the environment, and making efficient use of resources.

[0004] The aforementioned concrete waste is a waste material containing calcium, and a technology has been proposed to produce calcium carbonate by carbonating the waste with carbon dioxide (see Patent Document 1).

[0005] Japanese Patent Publication No. 2006-69860

[0006] However, when producing calcium carbonate using calcium contained in concrete waste, the manufacturing process is complex, making it difficult to carry out the carbonation reaction simply and efficiently, and also presenting economic challenges.

[0007] Therefore, the present invention relates to a CaO-containing composition that can reduce the burden on the environment and efficiently carry out 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 article, and a CO2-containing inorganic molded article. ２ The objective is to provide a method for increasing the fixation rate.

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

[0009] That is, 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 SiO ２ is 5% by mass or more and 50% by mass or less, the content of Al ２ O ３ is 1% by mass or more and 20% by mass or less, the content of Fe ２ O ３ 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.

[0010] The CaO-containing composition of the present invention preferably has a SO ３ content of 0.8% by mass or more and 10% by mass or less.

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

[0012] The CaO-containing composition of the present invention preferably has the CaO-containing raw material derived from at least one of incineration ash of papermaking sludge, incineration ash of chicken manure, cement sludge, incineration ash of cement sludge, and their hydrates.

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

[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, including 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, it is preferable that the preparation step includes a pulverization step of pulverizing a CaO-containing raw material.

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

[0018] In the method for producing calcium-based carbonate compounds of the present invention, it is preferable that the carbon dioxide used in the carbonation step is carbon dioxide emitted from a combustion engine.

[0019] In the method for producing calcium-based carbonate compounds of the present invention, it is preferable that the temperature in the carbonation step is 5°C or higher and 95°C or lower.

[0020] The present invention relates to a calcium-based carbonate compound, which is a carbon oxide in the CaO-containing composition.

[0021] The calcium-based carbonate compound of the present invention is 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 Preferably, the content is 0.5% by mass or more and 15% by mass or less, and the average particle size measured by laser diffraction is 1 μm or more and 50 μm or less.

[0022] The calcium-based carbonate compound of the present invention is SO ３ The content of is preferably 0.8% by mass or more and 10% by mass or less.

[0023] The calcium-based carbonate compound of the present invention is CO ２ It is preferable that the immobilization rate is 5% by mass or more.

[0024] The calcium-based carbonate compound of the present invention has a BET specific surface area of ​​5 m². ２ / g or more 200m ２ It is preferable that the amount is less than or equal to / g.

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

[0026] The calcium-based carbonate compound of the present invention is preferably for use in inorganic molded articles.

[0027] The present invention relates to an inorganic molded article containing the calcium-based carbonate compound.

[0028] This invention uses ultrafine pulverized water-granulated slag to form the CO2 of the inorganic molded body.２ Regarding methods for increasing the fixation rate.

[0029] This invention relates to CaCO ３ A calcium-based carbonate compound containing 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 This invention relates to a calcium-based carbonate compound having a content of 0.5% by mass or more and 15% by mass or less, and an average particle size of 1 μm or more and 50 μm or less as determined by laser diffraction.

[0030] The calcium-based carbonate compound of the present invention is the CaCO3 ３ It is preferable that the content of is 10% by mass or more.

[0031] The calcium-based carbonate compounds of the present invention are preferably obtained using carbon dioxide emitted from a combustion engine.

[0032] In this specification, standard abbreviations for elements from the periodic table are used, for example, C for carbon, Ca for calcium, O for oxygen, H for hydrogen, Si for silicon, Fe for iron, Al for aluminum, and S for sulfur. The same applies to other elements.

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

[0034] In this specification, "calcium-based carbonate compound" refers to a compound containing calcium carbonate, and is a concept that allows for the inclusion or coexistence of other by-components that may be incorporated during the manufacturing process, etc.

[0035] According to the present invention, a CaO-containing composition that can reduce the burden on the environment and efficiently carry out 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 article, and a CO2-containing inorganic molded article. ２This method can provide a way to increase the immobilization rate, which is useful. In particular, by using the calcium-based carbonate compound, an inorganic molded article with increased strength can be obtained.

[0036] CO ２ This is a schematic cross-sectional view showing the instrument for measuring the content of [ingredient]. This is an SEM image of the calcium carbonate compound of Example 2-1 of the present invention. This is an SEM image of the calcium carbonate compound of Example 2-2 of the present invention. This is an SEM image of the calcium carbonate compound of Example 2-3 of the present invention. This is an SEM image of the calcium carbonate compound of Comparative Example 2-1 of the present invention. This is a schematic partial perspective view showing the heating tester.

[0037] The present invention relates to a CaO-containing composition, a method for producing a calcium-based carbonate compound, a calcium-based carbonate compound, an inorganic molded article, and the CO of an inorganic molded article. ２ Methods for increasing the immobilization rate are described below. The present invention is not limited to these embodiments.

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

[0039] The CaO-containing composition has a free CaO content of 15% by mass or more and less than 50% by mass, preferably 18% by mass or more and 49% by mass or less, more preferably 20% by mass or more and 48% by mass or less, and even more preferably 22% by mass or more and 47% by mass or less. By using a CaO-containing composition with a low CaO content, it is possible to use raw materials that reduce the environmental impact, and in the carbonation process when producing calcium-based carbonate compounds using the CaO-containing composition, the carbonation reaction can be carried out efficiently without adding seed crystals or performing other operations (processes), thereby obtaining the calcium-based carbonate compound, which is useful.

[0040] The CaO-containing composition is SiO ２ The content of is preferably 5% by mass or more and 50% by mass or less, preferably 8% by mass or more and 48% by mass or less, and more preferably 10% by mass or more and 45% by mass or less. This makes it possible to improve the strength of the inorganic molded article containing the calcium carbonate compound obtained using the CaO-containing composition.

[0041] The CaO-containing composition is Al ２ O ３ The content of is preferably 1% by mass or more and 20% by mass or less, preferably 2% by mass or more and 18% by mass or less, and more preferably 3% by mass or more and 15% by mass or less. This makes it possible to improve the strength of the inorganic molded article containing the calcium carbonate compound obtained using the CaO-containing composition.

[0042] The CaO-containing composition is Fe ２ O ３ The content of is preferably 0.5% by mass or more and 15% by mass or less, preferably 1% by mass or more and 12% by mass or less, and more preferably 1.5% by mass or more and 10% by mass or less. This makes it possible to improve the strength of the inorganic molded article containing the calcium carbonate compound obtained using the CaO-containing composition.

[0043] The CaO-containing composition has an average particle size 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, as determined by laser diffraction. This makes it possible to obtain a CaO-containing composition with high reaction activity with carbon dioxide.

[0044] The CaO-containing composition is SO ３ The content of is preferably 0.8% by mass or more and 10% by mass or less, more preferably 0.9% by mass or more and 9% by mass or less, and even more preferably 1.0% by mass or more and 8% by mass or less. This makes it easier to control the curing time of the inorganic molded article containing the calcium carbonate compound obtained using the CaO-containing composition, and makes it possible to obtain an inorganic molded article with high strength.

[0045] The CaO-containing composition is preferably a pulverized product of a CaO-containing raw material. Being a pulverized product is preferable because, compared to the CaO-containing raw material before pulverization, it has a larger surface area, which allows the carbonation reaction to proceed more easily in the subsequent carbonation step for producing the calcium-based carbonate compound.

[0046] The CaO-containing composition is preferably derived from at least one of the following: incinerated ash from papermaking sludge, incinerated ash from chicken manure, cement sludge, incinerated ash from cement sludge, and hydrates thereof. Various materials can be used as the CaO-containing material, but the use of waste is particularly preferable from the viewpoint of economic efficiency and waste reduction. Since waste derived from incinerated ash from papermaking sludge, incinerated ash from chicken manure, etc., has a relatively high free CaO content, it has a low environmental impact, is economically superior, and allows for the simple and efficient production of a CaO-containing composition.

[0047] The CaO-containing composition has a BET specific surface area of ​​1 m². ２ / g or more 100m ２ It is preferable that it be less than or equal to 4m ２ / g or more 60m ２ It is more preferable that it be less than or equal to 8m ２ / g or more 30m ２It is even more preferable that the amount is less than or equal to / g. This makes it possible to obtain a CaO-containing composition with high reaction activity with carbon dioxide.

[0048] CO in the aforementioned CaO-containing composition ２ The content of is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less. ２ While a low content of CO is preferable, it may be 0.5% by mass or more, 1% by mass or more, or 1.5% by mass or more. ２ It is mainly derived from calcium carbonate. ２ By keeping the content of [unspecified substance] low, the content of free CaO can be increased.

[0049] The CaO-containing composition of the present invention is preferably intended for recycling. As described above, the raw materials for the CaO-containing composition can be incinerated paper sludge ash or incinerated chicken manure ash. When these raw materials are waste, their reuse can be realized from the viewpoint of conserving natural resources, protecting the environment, and effectively utilizing resources, making them useful.

[0050] <Method for producing calcium carbonate compounds> The method for producing the calcium 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 carbonate compound. As a result, the CO in the obtained calcium carbonate compound ２ This can improve the rate of fixation.

[0051] (Grinding step) The method for producing the calcium carbonate compound preferably includes a grinding step as a preparation step in which the CaO-containing raw material is ground. The grinding step produces free CaO particles (or free (CaO) ｍ (H ２ O) ｎBy crushing the particles, the material can be made finer, and a CaO-containing composition with high reaction activity with carbon dioxide can be prepared. The CaO-containing raw material may be either a sieved product, which has undergone a sieving process in addition to the crushing process as a preparation step, and the sieved portion recovered, or an unsieved product that has not undergone the sieving process. However, from the viewpoint of simplifying the manufacturing process and economic efficiency, it is preferable to use an unsieved product that has not undergone the sieving process.

[0052] The grinding method is not particularly limited, and a method using a known grinding machine can be employed. Examples of grinding machines include roller mills; jet mills; high-speed rotary grinding machines such as hammer mills, cutter mills, and pin mills; container-driven mills such as rotary mills, vibratory mills, and planetary mills; and media stirring mills such as attritors, bead mills, ball mills, and rod mills.

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

[0054] When using a rotary mill such as a ball mill or pot mill as a grinder, the rotational speed is preferably 10 rpm to 300 rpm, more preferably 50 rpm to 200 rpm, and even more preferably 60 rpm to 150 rpm.

[0055] The grinding process may be carried out either dry or wet. When the grinding process is carried out wet, water is usually used as the dispersion medium. The concentration of the CaO-containing raw material when dispersed in water can be set appropriately considering the grinding efficiency, etc. The amount of CaO-containing raw material 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] If the grinding process is carried out in a wet manner, the suspension may be subjected to the next step, the carbonation step, or it may be subjected to the carbonation step after drying.

[0057] As described above, by performing the grinding step as a preparation step, a CaO-containing composition with high reaction activity with carbon dioxide can be suitably prepared.

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

[0059] The solid content concentration of the CaO-containing composition in the dispersion can be set appropriately considering the 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] If the grinding process is performed dry, the resulting CaO-containing composition may be dispersed in water to achieve the concentration range. If the grinding process is performed wet, water may be added or removed from the resulting suspension of the CaO-containing composition to achieve the concentration range.

[0061] In the carbonation process, the carbon dioxide is preferably carbon dioxide (carbonic acid gas) emitted from a combustion engine. The carbon dioxide gas used in the carbon dioxide gas method can be exhaust gas containing carbon dioxide emitted from combustion engines such as the flue gas of a lime calcination furnace located near a calcium carbonate compound manufacturing plant, boilers, or waste incinerators. This allows for the reuse of carbon dioxide secondarily generated in industrial processes, 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 process 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 (temperature of the dispersion) is preferably 5°C to 95°C, more preferably 15°C to 85°C, and even more preferably 25°C to 75°C.

[0064] As for the flow rate of the carbon dioxide gas, from the viewpoint of carbonation efficiency and production capacity, it is preferable that it is 10 L / min or more and 200 L / min or less per 10 kg of raw material CaO, 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.

[0065] In the carbonation step, it is preferable to stir the mixture in conjunction with blowing in carbon dioxide. When stirring is performed using a stirring blade, the rotational speed is preferably 100 rpm to 600 rpm, more preferably 150 rpm to 550 rpm, and even more preferably 200 rpm to 500 rpm.

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

[0067] In addition to the carbon dioxide method described above, an alkali (NaOH, amine, etc.) and CO2 can be used. ２ reacting with Na ２ CO ３ First, prepare an amine carbonate, and then react it with CaO to produce CaCO₃. ３ A solution method for generating the product is also suitable.

[0068] By following the above steps, a calcium-based carbonate compound obtained as a carbon oxide of the CaO-containing composition can be produced. The obtained calcium-based carbonate compound may be filtered and dried to obtain a powder, or it may be used as a source of calcium-based carbonate compound in slurry or cake form without filtering and drying.

[0069] <Calcium-based carbonate compound> The calcium-based carbonate compound is preferably a carbon oxide of the CaO-containing composition. By using the carbon oxide of the CaO-containing composition, it is possible to contribute to waste reduction and effective utilization, as well as carbon dioxide reduction.

[0070] The calcium carbonate compound is 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 Preferably, the content is 0.5% by mass or more and 15% by mass or less, and the average particle size measured by laser diffraction is 1 μm or more and 50 μm or less.

[0071] The calcium carbonate compound is SiO ２ The content of the calcium carbonate compound is preferably 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. This makes it possible to improve the strength of the inorganic molded article containing the calcium carbonate compound.

[0072] The aforementioned calcium carbonate compound is Al ２ O ３ The content of the calcium carbonate compound is preferably 1% by mass or more and 20% by mass or less, more preferably 2% by mass or more and 18% by mass or less, and even more preferably 3% by mass or more and 15% by mass or less. This makes it possible to improve the strength of the inorganic molded article containing the calcium carbonate compound.

[0073] The calcium carbonate compound is Fe ２ O ３ The content of is preferably 0.5% by mass or more and 15% by mass or less, more preferably 1% by mass or more and 12% by mass or less, and even more preferably 1.5% by mass or more and 10% by mass or less. This makes it possible to improve the strength of the inorganic molded article containing the calcium carbonate compound.

[0074] The calcium-based carbonate compound preferably has an average particle size of 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, as determined by laser diffraction. This makes it possible to improve the physical properties of the object to which the calcium-based carbonate compound is applied (for example, the strength and fire resistance of inorganic molded articles).

[0075] The aforementioned calcium carbonate compound is SO ３ The content of is preferably 0.5% by mass or more and 10% by mass or less, more preferably 0.8% by mass or more and 8% by mass or less, and even more preferably 1% by mass or more and 6% by mass or less. This makes it easier to control the curing time of the inorganic molded article containing the calcium carbonate compound, and makes it possible to obtain an inorganic molded article with high strength.

[0076] The aforementioned calcium carbonate compound has a BET specific surface area of ​​5 m². ２ / g or more 200m ２ It is preferable that it be less than or equal to 7m ２ / g or more 150m ２ It is more preferable that it be less than or equal to 10m ２ / g or more 100m ２ It is even more preferable that the concentration be less than or equal to / 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] CO in the aforementioned calcium carbonate compound ２ The content of CO 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. ２This mainly originates from calcium carbonate. By setting this value within the aforementioned 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. Note that the CO in the calcium carbonate compound ２ The content of is the CO content in the CaO-containing composition. ２ and newly fixed CO ２ This shows the total content percentage of the combined substance.

[0079] CO in the aforementioned calcium carbonate compound ２ The immobilization rate should be as high as possible from an environmental perspective, but preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. ２ The immobilization rate is CO in calcium carbonate compounds. ２ From the content, the CO in the CaO-containing composition ２ This is the value after subtracting the content percentage.

[0080] The production rate of calcium-based carbonate compounds that contribute to carbon dioxide fixation is desirable as high as possible, 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-based carbonate compound preferably contains calcite. Since the calcite is based on the crystalline structure of calcium carbonate and has a small particle size (about 10 μm) and good dispersibility, it can improve the strength of the inorganic molded article containing the calcium-based carbonate compound.

[0082] The calcium-based carbonate compound of the present invention is preferably for use in inorganic molded articles. The calcium-based carbonate compound contains SiO, which contributes to the hardening process. ２ Because it contains such materials, it can be used in applications such as the aforementioned inorganic molded articles, and is therefore useful.

[0083] In view of the synthesis procedure, the calcium-based carbonate compound is preferably a synthetic calcium-based carbonate compound. By using a synthetic calcium-based carbonate compound, which is a reaction product of a CaO-containing composition and carbon dioxide gas, it is possible to reuse the carbon dioxide generated secondarily in an industrial process and contribute to reducing the carbon dioxide emissions in the entire industrial process.

[0084] Further, the present invention relates to a calcium-based carbonate compound containing CaCO ３ and having a SiO ２ content of 5% by mass or more and 50% by mass or less, an Al ２ O ３ content of 1% by mass or more and 20% by mass or less, an Fe ２ O ３ content of 0.5% by mass or more and 15% by mass or less, and an average particle diameter by the laser diffraction method of 1 μm or more and 50 μm or less.

[0085] The calcium-based carbonate compound preferably has a higher CaCO ３ content from the perspective of the environmental aspect, but is preferably 10% by mass or more, more preferably 15% by mass or more, and still more preferably 20% by mass or more. Also, from the perspective of maintaining the strength of the inorganic molded body containing the calcium-based carbonate compound, the CaCO ３ content in the calcium-based carbonate compound may be less than 80% by mass, may be less than 75% by mass, or may be less than 70% by mass.

[0086] The calcium-based carbonate compound of the present invention is preferably obtained using carbon dioxide (carbon dioxide gas) emitted from a combustion engine. As for the method of producing the calcium-based carbonate compound, as detailed in the carbonation step, the carbon dioxide (carbon dioxide gas) used in the carbon dioxide gas method can be exhaust gas containing carbon dioxide gas emitted from combustion engines such as lime calcination furnaces, boilers, and waste incinerators, which are installed in close proximity to the calcium-based carbonate compound production plant. This makes it possible to reuse carbon dioxide secondarily generated in industrial processes, contributing to a reduction in carbon dioxide emissions throughout the entire industrial process.

[0087] <Uses of Calcium-Based Carbonates> The uses of the calcium-based carbonates are not particularly limited, but they are suitable, for example, as high-performance materials for inorganic molded articles such as building materials, and as fillers for resins. The following describes how calcium-based carbonates are used in inorganic molded articles.

[0088] <Inorganic Molded Body> The present invention relates to an inorganic molded body containing the calcium-based carbonate compound. The inorganic molded body containing the calcium-based carbonate compound comprises calcium carbonate and SiO2, which is an impurity. ２ Because it is a mixture of such materials, it is useful in improving compressive strength and fire resistance.

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

[0090] The aforementioned inorganic molded articles are molded articles composed mostly of inorganic substances such as hydraulic materials and silicate materials, and because they possess properties such as fire resistance, light weight, high strength, and workability, they are widely used as exterior wall materials, roof underlayment materials, and eaves ceiling materials for houses and other buildings. They are also widely used in the foundations, walls, columns, and floors of buildings where strength and fire resistance are required. By using specific calcium-based carbonate compounds in these inorganic molded articles, it is possible to reduce the environmental burden on the entire industrial process.

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

[0092] (Hydraulic Materials) Examples of hydraulic materials include cementitious materials, gypsum, lime, and slag. Examples of cementitious materials 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 individually or in combination of two or more.

[0093] The hydraulic material content is preferably 5% to 45% by mass, more preferably 8% to 42% by mass, and even more preferably 10% to 40% by mass, based on the total amount of material constituting the molded board. By setting the hydraulic material content within the above range, the physical properties of the molded board, such as bending strength and peel strength, can be improved, and the bulk density of the molded board can be suppressed, thereby improving workability during construction.

[0094] (Silicate materials) Examples of siliceous materials include 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.) containing SiO ２ Examples of materials containing a large amount of these materials include siliceous materials. These siliceous materials can be used individually or in combination of two or more. Talc, mica, and wollastonite can also be used as reinforcing fiber materials, as 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 the materials constituting the molded plate. 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 plate within the target range. As the siliceous material, perlite, fly ash balloon, shirasu balloon, etc. with a unit volume mass of 0.5 g / cm ３ When blending the following lightweight aggregates, in order to prevent the bulk specific gravity from becoming too light and the strength such as bending strength and peel strength from becoming weak, it is preferable to use other siliceous materials in combination so that the content of the lightweight aggregate is 20% by mass or less based on the total amount of the materials constituting the molded plate.

[0096] (Reinforcing fiber material) As the reinforcing fiber material, for example, pulp such as softwood pulp, hardwood pulp, fibrillated pulp 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 can be used. These reinforcing fiber materials can be used alone or in combination of two or more.

[0097] For improving the strength and imparting toughness of the molded plate, 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 the materials constituting the molded plate. By setting the content of the reinforcing fiber material within the above range, it is possible to improve the smoothness by suppressing the fibers from protruding on the surface of the molded plate while exhibiting a sufficient reinforcing effect. When an inorganic reinforcing fiber material with an average fiber length of 1 mm or more and 50 mm or less is blended as the reinforcing fiber material, in order to improve the smoothness of the molded plate, it is preferable to use other reinforcing fiber materials in combination so that the content thereof is 10% by mass or less based on the total amount of the materials constituting the molded plate.

[0098] (Calcium carbonate compound) As the calcium carbonate compound, the above-mentioned calcium carbonate compound can be preferably adopted.

[0099] The content of the calcium carbonate compound is preferably 5% to 60% by mass, more preferably 8% to 55% by mass, and even more preferably 12% to 50% by mass, based on the total amount of material constituting the molded board. By incorporating a low thermal conductivity calcium carbonate compound in the above-mentioned range, the strength and fire resistance of the molded board can be improved.

[0100] (Optional Components) In addition to the above-mentioned materials, various materials such as hollow resin bodies, wood chips, wood powder, resin powder, defoamers, flocculants, water repellents, thickeners (methylcellulose, hydroxyethyl methylcellulose, hydroxypropyl methylcellulose, etc.), and dispersants can be added to the molded board in order to impart various functions, depending on the purpose. It is also possible to add recycled materials, such as crushed scraps generated during the processing of the molded board, as appropriate.

[0101] The bulk density of the molded plate is 0.7 g / cm³. ３ Preferably, it is 0.8 g / cm³ or more. ３ It is more preferable that the value be greater than or equal to 0.9 g / cm³. ３ It is even more preferable that the above conditions are met. This makes it possible to improve the strength of the molded plate.

[0102] (Method for manufacturing molded sheets) The method for manufacturing the molded sheets is not particularly limited, and commonly used methods such as papermaking, extrusion molding, flow-on molding, pour molding, and press (compression) molding can be used. The molded sheets can be obtained by molding green sheets using these methods, then dewatering them by press or embossing to create a pattern, and finally curing them at room temperature, with steam, or in an autoclave. Furthermore, drying may be performed, and shaping or painting may be carried out as needed.

[0103] (Uses of molded boards) The uses of the molded boards are not particularly limited and can be suitably used as wall materials, floor materials, roofing materials, various boards, exterior decorative members, interior and exterior finishing materials such as joinery, sealing materials, heat insulating materials, sound absorbing materials, waterproofing materials, etc. The molded boards are preferably cement-based molded boards containing cementitious materials, and calcium silicate molded bodies are more preferable.

[0104] (Concrete Structures) Concrete structures are composed of hardened bodies of hydraulic compositions. The hydraulic composition consists of a powder containing a calcium carbonate compound, plus at least one of the following: blast furnace slag, expansive agent, slaked lime, quicklime, fly ash, and Portland cement. The calcium carbonate compound described above can be suitably used as the calcium carbonate compound.

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

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

[0107] The proportion of the calcium carbonate compound in the powder (the proportion 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 preferable to use blast furnace slag fine powder used in JIS (Japanese Industrial Standards) R5211 "Blast Furnace Cement" or blast furnace slag fine powder conforming to JIS A6206 "Blast Furnace Slag for Concrete" as the blast furnace slag. Furthermore, the specific surface area of ​​the blast furnace slag is preferably 2000 cm². ２ / g or more 10000cm ２ / g or less, more preferably 3500 cm２ / g or more 7000cm ２ Use products with a weight of 1g or less.

[0109] For example, an expansive material specified in JIS A6202 "Expansive Material for Concrete" may be used. It is desirable to add the expansive material at a ratio of 2 to 9% by mass relative to the entire hydraulic composition.

[0110] For the slaked lime mentioned above, for example, one specified in JIS R9001 "Industrial Lime" may be used. Also, since quicklime turns into slaked lime when it comes into contact with water, for example, quicklime specified in JIS R9001 "Industrial Lime" can be used as a substitute for slaked lime. In this case, it is advisable to adjust the amount of water required for the quicklime to change into slaked lime. For the fly ash, for example, one conforming to JIS A6201 "Fly Ash for Concrete" may be used.

[0111] While ordinary Portland cement is used for the aforementioned Portland cement, other types of Portland cement specified in JIS R5210 "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 well as JIS R5214 "Eco-cement," can also be used.

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

[0113] Furthermore, when using Portland cement and blast furnace slag or fly ash, pre-mixed materials such as JIS R5211 "Blast Furnace Cement" or JIS R5213 "Fly Ash Cement" may be used individually or in combination.

[0114] Because a calcium-based carbonate compound having the aforementioned characteristics is used, the hydraulic composition and the hydraulic composition mixture exhibit good fluidity, and the hardened concrete body can exhibit excellent compressive strength.

[0115] The density of the aforementioned concrete structure is 0.7 g / cm³. ３ Preferably, it is 0.8 g / cm³ or more. ３ It is more preferable that the value be greater than or equal to 0.9 g / cm³. ３ It is even more preferable that the above conditions are met. This improves the strength of the concrete structure.

[0116] <CO2 in inorganic molded material ２ Method for increasing the immobilization rate > This invention uses ultrafine pulverized water-granulated slag to increase the CO2 content of the inorganic molded body. ２ This invention relates to a method for increasing the fixation rate. The CaO-containing composition for producing the calcium-based carbonate compound obtained using the ultrafine pulverized material of the granulated slag has a large specific surface area, resulting in a large contact area with carbon dioxide and thus improving the carbon dioxide fixation rate. This composition is useful for improving the refractory properties of inorganic molded articles using this material. The ultrafine pulverized material refers to granulated slag (for example, the 1.2 mm blast furnace slag fine aggregate described later) that has been pulverized using a ball mill or the like to achieve a BET specific surface area of ​​50 m². ２ This refers to materials that are finely ground to a density of 5 μm or less per gram or more, with an average particle size of 5 μm or less.

[0117] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the invention. The measurement and evaluation of physical properties, etc., were carried out as shown below.

[0118] <Evaluation of CaO-containing compositions and calcium-based carbonate compounds> The CaO-containing compositions and calcium-based carbonate compounds (hereinafter, both may be referred to as "samples") obtained in the examples and comparative examples were analyzed and evaluated as follows. In all cases, whether the sample was dry, wet, or suspended, approximately 50 g was placed in a 200 mL petri dish and dried at 110°C for 12 hours before being used for analysis and evaluation. The results of the analysis and evaluation of the CaO-containing compositions are shown in Table 1, and the results of the analysis and evaluation of the calcium-based carbonate compounds are shown in Table 2. In addition, SEM images shown in Figures 2 to 5 were taken for calcium-based carbonate compounds 1 to 3 and calcium-based carbonate compound 6 (Examples 2-1 to 2-3, and Comparative Example 2-1).

[0119] (Loss on ignition) Approximately 2 g of the sample was placed in a porcelain crucible that had been pre-mass-measured and brought to a constant weight, and the total mass was accurately weighed. This was heated in an electric furnace at 900°C for more than 3 hours. After cooling to room temperature in a desiccator, the mass was accurately weighed, and the difference in mass before and after heating was determined as the loss on ignition. The loss on ignition (mass basis) was calculated based on the following formula. (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] (CaO, SiO ２ Fe ２ O ３ Al ２ O ３ and SO ３(Content of) <ICP-AES method> 0.2 g of the sample was weighed into a platinum crucible, 0.5 g of boric acid and 2.0 g of potassium carbonate were added, and it was melted in an electric furnace at 900°C for 30 minutes. After cooling, the platinum crucible was placed in a 200 mL beaker, and 50 mL of hydrochloric acid (a solution of concentrated hydrochloric acid and water mixed in a 1:1 volume ratio) was added using a dispenser, and it was heated and dissolved. After cooling, it was transferred to a 250 mL volumetric flask, and water was added to the same volume of 250 mL to make up the volume. 20 mL was taken from here and transferred to a 50 mL volumetric flask, and water was added to the same volume of 50 mL to prepare the sample solution for measurement. Meanwhile, 20 mL was taken from the 250 mL volumetric aqueous solution 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 curve standard solutions of different concentrations. For each element, a commercially available 1000 ppm atomic absorption standard solution was used.

[0121] Calibration standard solutions and measurement sample solutions of different concentrations, each containing an additional element, were placed in the autosampler of an inductively coupled plasma atomic emission spectrometer (ICP-AES) (Hitachi High-Tech Science Corporation, "SPECTROBLUE FMS36"), and the amounts (ppm) of Ca, Si, Fe, Al, and S were measured under the following conditions. <Measurement Conditions> High-frequency output: 1.4 kW Carrier gas (humidification) flow rate: 0.9 L / min Plasma gas flow rate: 13.0 L / min Auxiliary gas flow rate: 1.0 L / min Liquid properties: Aqueous solution Number of integrations: 3 Sample order: Each sample Measurement method: Standard addition method Weighting of calibration curve: None Measurement wavelengths: 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 calculated amount of each element, and converted to oxides for CaO, SiO ２ Fe ２ O ３ Al ２ O ３ and SO ３ The content (mass %) was calculated.

[0122] (CO ２(Content of) The reagents used for the measurement were prepared as follows: ・1 / 10N barium hydroxide solution: 15.8 g of barium hydroxide (octahydrate) was dissolved in ultrapure water to make a total volume of 1000 mL. After sealing the bottle tightly and shaking well, it was allowed to stand for at least one day, and the supernatant liquid was taken out 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: 1 g of phenolphthalein was dissolved in ethanol to make a total volume of 100 mL.

[0123] Figure 1 shows CO ２ This is a schematic diagram showing a measuring device for measuring the content of [substance]. Gas circulated within the measuring device by a circulation pump, maintaining an airtight state during circulation. In the diagram, arrows indicate the direction of gas flow.

[0124] Using the measuring device shown in Figure 1, CO ２ The content (mass%) of was determined by the following procedure. 20.0 mL of 1 / 10 N barium hydroxide solution was taken into a 100 mL medium bottle, 2 drops of PP indicator were added, and the bottle was sealed. Separately, 0.1 g of the sample was taken into a 500 mL medium bottle, and water was added to make a total volume of 200 mL. Using a measuring cup, 10 mL of sulfuric acid was added to the dish, the bottle was immediately sealed, and the circulation pump was activated. After 90 minutes or more of operation, 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 to obtain a control. Based on the following formula, CO ２ The content (mass %) was calculated. (In the formula, C is CO) ２ This is the content (mass%). k is the coefficient (= 0.0022). f is the factor of the 1 / 10 N hydrochloric acid standard solution. a is the titration volume of the sample (mL). b is the titration volume of the control (mL). s is the sample volume (g).

[0125] (Free CaO content) The free CaO content Z (mass%) is calculated using the ignition loss, CaO content, and SO2 as described above. ３ Content rate and CO ２The calculation was performed using the following formula based on the content data. In the formula, "%" represents "mass%". (In the formula, p is the CaO content (mass%) in the CaO-containing composition, and q is the CO content in the CaO-containing composition.) ２ This is the content (mass %). r is SO in the CaO-containing composition. ３ This represents the content (mass%). x is the water content (mass%) lost during ignition in the CaO-containing composition. y is the loss during ignition in the CaO-containing composition (mass%).

[0126] (BET specific surface area) Sample powder, pre-treated in a nitrogen gas atmosphere at approximately 130°C for approximately 30 minutes using an 8-unit preheating unit (manufactured by MOUNTECH), was measured using a Macsorb HM Model-1208 (manufactured by MOUNTECH) as a BET specific surface area measuring device by nitrogen gas adsorption method to determine the BET specific surface area (m²). ２ The amount (per 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 added to the same 100 mL beaker. The dispersion was prepared by ultrasonic treatment (UD-201, manufactured by Tommy Seikou Co., Ltd.) for 3 minutes. The average particle size of this dispersion was determined by laser diffraction-particle size analyzer (Microtrac HRA Model 9320-X100, manufactured by Nikkiso Co., Ltd.) to determine the volume-based D ５０ The value was measured as the average particle diameter (μm).

[0128] (Crystal identification by XRD) After compacting and fixing the sample powder onto a designated sample stage using a spatula, measurements were performed using an XRD device (MiniFlex 600-C manufactured by Rigaku Corporation) to identify and analyze the crystalline material. It was confirmed that all of the obtained calcium carbonate compounds, as described later, contained calcite crystals.

[0129] (CO in calcium carbonate compounds) ２ (Isolation rate) CO in calcium carbonate compounds ２ The immobilization rate D (mass%) was calculated using the following formula. (wherein d is CO in calcium carbonate compounds) ２This is the content (mass %). e is the amount of CO in the CaO-containing composition. ２ (This is the content percentage by mass.)

[0130] (CO ２ (Formation rate of calcium-based carbonate compounds that contributed to immobilization) CO ２ The production rate E (mass%) of the calcium carbonate compound that contributed to immobilization was calculated using the following formula. (wherein d is CO in calcium carbonate compounds) ２ This is the content (mass %). e is the amount of CO in the CaO-containing composition. ２ (This is the content percentage by mass.)

[0131] (CaCO3 in calcium carbonate compounds) ３ (Content of) CaCO3 in calcium carbonate compounds ３ The content (mass%) of the calcium carbonate compound was calculated using the following formula: CaCO3 in the calcium carbonate compound. ３ The content is derived from the raw materials CaCO3. ３ And newly CO ２ CaCO2 fixed ３ This shows the total content percentage of the combined substance. (wherein d is CO in calcium carbonate compounds) ２ (This is the content percentage by mass.)

[0132] (Scanning Electron Microscope Observation) Double-sided tape was attached to an aluminum sample stage, and the sample powder was applied over it using a spatula. After platinum deposition, the particle image of the sample powder was captured using a scanning electron microscope (FE-SEM: Hitachi, Ltd. S-4700) at 1000x and 5000x magnification. For the obtained calcium-based carbonate compounds 1-3 and 6, SEM images shown in Figures 2-5 were taken to determine the particle size.

[0133] <Preparation of CaO-containing composition and production of calcium carbonate compound> (Examples 1-1 and 2-1) After filling an 8L capacity SUS container with baffles with 6L of water, 1.0 kg of dry paper sludge calcination ash (manufactured by Marusumi Paper Co., Ltd., sample name: BF ash, average particle size 10 μm) was dry-ground in a Wonder Crusher (CaO-containing composition 1) and added to the container under stirring. The temperature was then raised to 40°C, and the mixture was stirred at a rotation speed of 350 rpm using a stirrer equipped with a single stage turbine blade. Exhaust gas extraction piping was connected to the exhaust outlet of a steam production boiler fueled by LNG, and exhaust gas was drawn in using a test blower. ２ When measured with a concentration meter (XP-3140 manufactured by Shin-Cosmos Electric Co., Ltd.), the CO in the exhaust gas was ２ The concentration was 10% by volume. Exhaust gas was introduced into the aforementioned 8 L capacity SUS container using a test blower at a rate of 3.3 L / min and reacted for 10 hours. Next, the mixture was filtered, and the filtered wet material was dried at 110°C for 12 hours and pulverized to obtain a sample powder of calcium carbonate compound 1 (see Figure 2). For the analysis of the CaO-containing composition, the sample dried at 110°C for 12 hours was used (the same method was used for calcium carbonate compounds 2 to 5 below).

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

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

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

[0137] (Examples 1-5 and 2-5) As the CaO-containing composition, a cement-based solidified material (manufactured by Yonezawa Kogyo Co., Ltd., product name: Concrete Block Type A) was coarsely crushed with a hammer and then passed through a 4 mm sieve. The material under 4 mm was dry-crushed with a Wonder Crusher to prepare CaO-containing composition 5. Except for this, the same procedure as for calcium carbonate compound 1 was followed to obtain a sample powder of calcium carbonate compound 5.

[0138] (Comparative Examples 1-1 and 2-1) A sample powder of calcium carbonate compound 6 was obtained by performing the same procedure as for calcium carbonate compound 3, except that a water-granulated slag that had not undergone wet grinding (1.2 mm blast furnace slag fine aggregate (BFS1.2) of 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). The average particle size of the sample powder of calcium carbonate compound 6 exceeded the measurement limit (1000 μm) of the measuring device (laser diffraction method - particle size distribution analyzer) used in the measurement of the average particle size by the laser diffraction method, and therefore could not be evaluated.

[0139] (Preparation of molded bodies (concrete structures) of cement composition) The types and proportions of calcium carbonate compounds shown in Table 3 were added to 1600 g of water and stirred manually with a stirring rod for about 30 seconds. Then, a mixture was obtained by stirring at 400 rpm using a stirrer (Yamato Scientific Co., Ltd., "Labo Stirrer (LR500B)"). To this mixture, cement (Tokuyama Corporation, "Ordinary Portland Cement (N)") was added in the amount shown in the table over about 20 seconds and mixed with the stirrer for 3 minutes from the start of addition. After stopping the stirring and letting it stand for 3 minutes, cement milk was prepared by stirring 10 times manually with a stirring rod (AS ONE Corporation, "Stirring Rod (POM) φ10 × 300 mm"). For each cement milk, a small amount of dispersant (Levelflow EX) was added during stirring after cement addition to maintain a certain degree of fluidity during stirring. The final amount of dispersant added is shown in the table. For the blank (Comparative Example 3-1), 400 g of fine aggregate (crushed sand; less than 5 mm in size) was added instead of the calcium carbonate compound. 400 mL of the prepared cement milk was poured up to the mark in a cylindrical polyethylene bag (approximately 50 mm in diameter x approximately 550 mm in length x approximately 0.05 mm in thickness). After sealing the bag with as much air as possible, it was suspended in a constant temperature chamber set to 22°C. The chamber was left suspended for 28 days to harden the contents, producing a total of three molded cement compositions (concrete structures). The resulting molded cement compositions were cylindrical, with a diameter of approximately 5 cm and a length of approximately 20 cm.

[0140] <Evaluation of molded cement compositions (concrete structures)> In Examples 3-1 to 3-6, Comparative Example 3-1, and Comparative Example 3-2, the molded cement compositions (concrete structures) produced were evaluated as follows. The results are shown in Table 3.

[0141] (CO in cement composition) ２ (Isolation rate) CO in cement composition ２ The immobilization rate H (mass%) was calculated using the following formula. (In the formula, D is CO in calcium carbonate compounds) ２ This is the immobilization rate (mass%). In the formula, j is the amount of cement used (g), l is the amount of fine aggregate used (g), and m is the amount of calcium carbonate compound used (g). The CO in the cement composition ２ If you want to adjust the immobilization rate H to a target value, CO in calcium carbonate compounds ２ The immobilization rate D can be measured in advance, and the amount of calcium carbonate compound to be added during cement mixing can be adjusted by calculating and adding it (see Examples 3-1 and 3-6 described later). Note that the CO in the cement composition ２ Regarding the immobilization rate, a higher rate is preferable from an environmental perspective, but 0.5% by mass or more is preferred, 1% by mass or more is more preferred, and 1.5% by mass or more is even more preferred. Furthermore, in order to ensure the compressive strength of the cement composition, the CO2 in the cement composition is ２ The immobilization rate is preferably 40% by mass or less, more preferably 35% by mass or less, and even more preferably 30% by mass or less.

[0142] (Density) The density (g / cm³) of the molded body (concrete structure) of the obtained cement composition was determined in accordance with JIS A 5430:2008 (apparent density test). ３ ) was measured.

[0143] (Compressive Strength Test) The compressive strength (N / mm²) of the molded body (concrete structure) of the obtained cement composition was determined in accordance with JIS A 1108:2018 (Compression Test Method for Concrete). ２The compressive strength of the molded body (concrete structure) of the cement composition was measured. While a higher compressive strength is preferable, 32 N / mm² is considered good. ２ The above is preferable, and 34 N / mm ２ The above is more preferable: 36 N / mm ２ The above is even more preferable.

[0144] <Manufacturing of Inorganic Molded Articles (Building Materials)> Inorganic molded articles (building materials) were manufactured by papermaking according to the following procedure. Unless otherwise specified, the amounts of the components used are all expressed in "parts by mass".

[0145] (Example 4-1 and Comparative Example 4-1) The materials shown in Table 4 were placed in a poly container and stirred to obtain a raw material slurry. In Example 4-1, calcium carbonate compound 1 was used as the calcium carbonate compound (not used in Comparative Example 4-1). The raw material slurry was divided and placed into a filter lined with felt, and a laminate (28 mm long side x 24 mm short side x 14 mm thick) was produced by suction filtration using a vacuum pump. The laminate was removed from the filter and dewatered by pressing. The thickness after pressing was 13 mm. After autoclave curing (curing pressure (gauge pressure) 9 kgf; curing time 12 hr), the pressed body was dried in a dryer (105°C) for 24 hr. Both sides were polished with a sander to adjust the thickness to 12 mm to obtain an inorganic molded body.

[0146] <Evaluation of Inorganic Molded Articles> 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] (CO in inorganic molded products (building materials)) ２ (Isolation rate) CO2 in inorganic molded products (building materials) ２ The immobilization rate I (mass%) was calculated using the following formula. (In the formula, D is CO in calcium carbonate compounds) ２This is the immobilization rate (mass%). In the formula, n is the amount of cement used (parts by mass). o is the amount of silica sand used (parts by mass). t is the amount of pulp used (parts by mass). w is the amount of wollastonite used (parts by mass). In the formula, u is the amount of calcium carbonate compound used (parts by mass). The CO in the inorganic molded body (building material) ２ If you want to adjust the immobilization rate I to a target value (for example, 1.5% by mass or more), then CO in calcium carbonate compounds ２ The immobilization rate D can be measured in advance, and the amount of calcium carbonate compound to be added during the formulation of the inorganic molded body (building material) can be adjusted by calculating and adding it (see Example 4-1 below). Note that the CO in the inorganic molded body (building material) ２ The immobilization rate should be as high as possible, but preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 3% by mass or more. In addition, in order to ensure the strength of the inorganic molded body (building material), the CO in the inorganic molded body (building material) ２ The immobilization rate is preferably 40% by mass or less, more preferably 35% by mass or less, and even more preferably 30% by mass or less.

[0148] (Bulk Density) The bulk density of inorganic molded materials (building materials) was measured in accordance with JIS A 5430.

[0149] (Heating Test) The heating test was conducted using the following apparatus and procedure. Figure 6 is a schematic partial perspective view of the heating test apparatus. As shown in the figure, a refractory material was assembled between the test specimen and the heat source so that the temperature could be stabilized at around 900°C using an electric heater as the heat source, and a thermocouple was used to measure the temperature on the back surface of the test specimen. Specifically, an electric heater (1.2 kW heater) was fixed as the heat source equipment so that the distance between the heating surface side of the test specimen and the heat source was approximately 70 mm.

[0150] The test procedure was as follows: (1) A sacrificial plate was placed and preheated to 902°C, after which heating was temporarily stopped. (2) The test specimen was inserted after the heating surface had fallen below 200°C. (3) A thermocouple was placed in the center of the back surface (top surface in the diagram) of the test specimen, and a calcium silicate plate (approximately 30 mm x 70 mm) and a weight were placed on top and secured. (4) Heating was started and left for a predetermined time (45 minutes), and the temperature of the heating surface and back surface was recorded with a data logger. During this time, the temperature setting of the electric heater was 902°C on the heating surface side, and controlled by a temperature controller with a lower limit of 900°C. The temperature measurement interval of the data logger was set to every 10 seconds, and data was recorded at this interval. (5) After the test was completed, the test specimen was removed and the following items were measured (each item had also been measured before the test): Dimensions: The length and width of the back surface and heating surface were measured with calipers. Area of ​​the heating surface (mm²) before and after the test. ２ The heat shrinkage (%) was calculated and the heat shrinkage (%) was determined based on the following formula. Preferably, the heat shrinkage (%) is 3% or less. Furthermore, the temperature rise on the back surface before and after the test is preferably 450°C or less. (In the formula, S ０ This is the area of ​​the heated surface before the test, S １ (This represents the area of ​​the heated surface after the test.)

[0151]

[0152]

[0153]

[0154]

[0155] From the results in Tables 1 and 2 above, the average particle size of the CaO-containing compositions in the examples was smaller than that of the comparative examples, and the CO in the calcium carbonate compound ２ Immobilization rate, the CO ２ Production rate of calcium carbonate compounds that contributed to immobilization, CaCO3 in calcium carbonate compounds ３ The content levels were all higher compared to the comparative examples.

[0156] From the results in Table 3 above, the example using the desired calcium-based carbonate compound is CO ２It was confirmed that the desired properties in terms of immobilization rate, density, and compressive strength could be simultaneously satisfied.

[0157] From the results in Table 4 above, the example using calcium-based carbonate compounds showed CO2 levels compared to the comparative example. ２ It was confirmed that the desired characteristics could be simultaneously satisfied in all evaluations of the immobilization rate, heating surface shrinkage, and back surface temperature rise.

Claims

1. The free CaO content is 15% by mass or more and less than 50% by mass, and 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 A CaO-containing composition having a content of 0.5% by mass or more and 15% by mass or less, and an average particle size of 1 μm or more and 50 μm or less as determined by laser diffraction.

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

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

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

5. The BET specific surface area is 1 m² ２ / g or more 100m ２ The CaO-containing composition according to claim 1, wherein the amount is less than or equal to / g.

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

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

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

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

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

11. The method for producing a calcium-based carbonate compound according to claim 7, wherein the temperature in the carbonation step is 5°C or higher and 95°C or lower.

12. A calcium-based carbonate compound which is a carbon oxide of the CaO-containing composition according to any one of claims 1 to 6.

13. The content of SiO ２ is 5% by mass or more and 50% by mass or less, and the content of Al ２ O ３ is 1% by mass or more and 20% by mass or less, and the content of Fe ２ O ３ 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. The calcium-based carbonate compound according to claim 12.

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

15. CO ２ The calcium-based carbonate compound according to claim 12, wherein the immobilization rate is 5% by mass or more.

16. The BET specific surface area is 5 m². ２ / g or more 200m ２ The calcium-based carbonate compound according to claim 12, wherein the amount is less than or equal to / g.

17. The calcium carbonate compound according to claim 12, which contains calcite.

18. The calcium-based carbonate compound according to claim 12, for use in inorganic molded articles.

19. An inorganic molded article containing the calcium-based carbonate compound according to claim 12.

20. Using ultrafine pulverized water-granulated slag, the CO2 of the inorganic molded body according to claim 19 ２ Methods to increase the fixation rate.

21. CaCO ３ A calcium-based carbonate compound containing 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 A calcium-based carbonate compound having a content of 0.5% by mass or more and 15% by mass or less, and an average particle size of 1 μm or more and 50 μm or less as determined by laser diffraction.

22. The aforementioned 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-based 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 The calcium-based carbonate compound according to claim 21, wherein the immobilization rate is 5% by mass or more.

25. The BET specific surface area is 5 m². ２ / g or more 200m ２ The calcium carbonate compound according to claim 21, wherein the amount is less than or equal to / g.

26. The calcium carbonate compound according to claim 21, which contains calcite.

27. The calcium-based carbonate compound according to claim 21, obtained using carbon dioxide emitted from a combustion engine.

28. The calcium-based carbonate compound according to claim 21, for use in inorganic molded articles.

29. An inorganic molded article containing the calcium-based carbonate compound described in claim 21.

30. Using ultrafine pulverized water-granulated slag, the CO2 of the inorganic molded body according to claim 27 ２ Methods to increase the fixation rate.

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