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.

Abstract

The present invention provides a CaO-containing composition that minimizes environmental impact and allows for efficient carbonation reactions, a method for producing calcium-based carbonate compounds using the CaO-containing composition, a calcium-based carbonate compound, an inorganic molded article, and a method for increasing the CO2 fixation rate of the inorganic molded article. [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, an Fe2O3 content of 0.5% by mass or more and 15% by mass or less, and an average particle diameter of 1 μm or more and 50 μm or less as determined by laser diffraction.

Description

[Technical Field]

[0001] 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 a method for increasing the CO2 fixation rate of the inorganic molded article. [Background technology]

[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 said waste with carbon dioxide (see Patent Document 1). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2006-69860 [Overview of the project] [Problems that the invention aims to solve]

[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, an object of the present invention is to provide a CaO-containing composition capable of suppressing the environmental load and efficiently promoting the 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 immobilization rate of the inorganic molded body.

Means for Solving the Problems

[0008] As a result of intensive studies, the present inventor has found that the above problems can be solved by the following configuration, and has 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 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.

[0010] The CaO-containing composition of the present invention preferably has a SO3 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 paper 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 has a BET specific surface area of 1 m 2 / g or more and 100 m 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, comprising a preparation step of preparing the CaO-containing composition and a carbonation step of contacting the CaO-containing composition with carbon dioxide (carbonic acid gas) to form a calcium-based carbonate compound.

[0016] In the method for producing calcium-based carbonate compounds of the present invention, it is preferable that the preparation step includes a grinding step of grinding the CaO-containing raw material.

[0017] In the method for producing calcium-based carbonate compounds 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 between 5°C and 95°C.

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

[0021] The calcium-based carbonate compound of the present invention preferably has an SiO2 content of 5% to 50% by mass, an Al2O3 content of 1% to 20% by mass, an Fe2O3 content of 0.5% to 15% by mass, and an average particle diameter of 1 μm to 50 μm as determined by laser diffraction.

[0022] The calcium-based 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-based carbonate compound of the present invention preferably has a CO2 fixation rate of 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 value be 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] The present invention relates to a method for increasing the CO2 fixation rate of an inorganic molded body using ultrafine pulverized water-granulated slag.

[0029] The present invention relates to a calcium carbonate compound containing CaCO3, wherein the SiO2 content is 5% by mass or more and 50% by mass or less, the Al2O3 content is 1% by mass or more and 20% by mass or less, the Fe2O3 content 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.

[0030] The calcium-based carbonate compound of the present invention preferably has a CaCO3 content of 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. [Effects of the Invention]

[0035] The present invention provides a CaO-containing composition that minimizes environmental impact and efficiently promotes the 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 method for increasing the CO2 fixation rate of the inorganic molded article, which are all useful. In particular, the use of the calcium-based carbonate compound makes it possible to obtain an inorganic molded article with increased strength. [Brief explanation of the drawing]

[0036] [Figure 1] This is a schematic cross-sectional view showing a device for measuring CO2 content. [Figure 2] This is an SEM image of the calcium-based carbonate compound of Example 2-1 of the present invention. [Figure 3] This is an SEM image of the calcium-based carbonate compound of Example 2-2 of the present invention. [Figure 4] These are SEM images of calcium-based carbonate compounds according to Examples 2-3 of the present invention. [Figure 5] This is an SEM image of a calcium-based carbonate compound of Comparative Example 2-1 of the present invention. [Figure 6] This is a schematic partial perspective view of a heating tester. [Modes for carrying out the invention]

[0037] The CaO-containing composition, method for producing a calcium-based carbonate compound, calcium-based carbonate compound, inorganic molded body, and 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 having a free CaO content of 15% by mass or more and less than 50% by mass, a 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 diameter by laser diffraction method of 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, still 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, raw materials with reduced environmental impact can be used. Also, in the carbonation step for 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] 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 still 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 by using the CaO-containing composition can be improved.

[0041] The CaO-containing composition has an Al2O3 content of 1% to 20% by mass, preferably 2% to 18% by mass, and more preferably 3% to 15% by mass. 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 has an Fe2O3 content of 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 a 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 preferably has an SO3 content of 0.8% to 10% by mass, more preferably 0.9% to 9% by mass, and even more preferably 1.0% to 8% by mass. 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 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. Although various materials can be used as the CaO-containing raw material, using waste is preferable from the viewpoints of economy and waste reduction. Waste derived from incineration ash of papermaking sludge or chicken manure has a relatively high content rate of free CaO, so it has a low environmental impact, is excellent in economy, and can obtain a CaO-containing composition simply and efficiently.

[0047] The BET specific surface area of the CaO-containing composition is preferably 1 m 2 / g or more and 100 m 2 / g or less, more preferably 4 m 2 / g or more and 60 m 2 / g or less, and even more preferably 8 m 2 / g or more and 30 m 2 / g or less. Thereby, a CaO-containing composition with high reaction activity with carbon dioxide can be obtained.

[0048] The content rate of CO2 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. Although it is preferable that the content rate of CO2 is low, it may be 0.5% by mass or more, 1% by mass or more, or 1.5% by mass or more. Note that CO2 mainly comes from calcium carbonate. By suppressing the content rate of CO2 low, the content rate of free CaO can be improved.

[0049] The CaO-containing composition of the present invention is preferably for recycling. As the raw material of the CaO-containing composition, as described above, incineration ash of papermaking sludge, incineration ash of chicken manure, etc. can be used. When these raw materials are waste, their reuse can be realized and is useful from the viewpoints of saving natural resources, environmental protection, and effective utilization of resources.

[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 the calcium carbonate compound. This makes it possible to improve the CO2 fixation rate in the resulting calcium carbonate compound.

[0051] (Grinding process) The method for producing the calcium carbonate compound preferably includes a grinding step of grinding the CaO-containing raw material as a preparation step. The aforementioned grinding process produces free CaO particles (or free (CaO) m (H2O) n By crushing the particles, they 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 undergoes a sieving process in addition to the grinding process as part of the preparation steps, and in which the CaO-containing raw material is sieved and the sieved portion is 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 to 1000 g, more preferably 80 g to 500 g, and even more preferably 120 g to 400 g.

[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 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-based carbonate compound. While the carbonation method is not particularly limited, a carbon dioxide method is preferred, in which carbon dioxide gas is blown into a dispersion of a CaO-containing composition in water to carbonate 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 can be dispersed in water to achieve the concentration range mentioned above. If the grinding process is carried out in a wet manner, the resulting CaO-containing composition suspension may be used after adding or removing water so that its concentration falls within the aforementioned 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 used in the aforementioned carbon dioxide process can be exhaust gas containing carbon dioxide from the flue of lime calcination furnaces located near calcium carbonate compound manufacturing plants, or from combustion engines such as boilers and waste incinerators. This allows for the reuse of carbon dioxide secondarily generated in industrial processes, contributing to a reduction in overall carbon dioxide emissions from industrial processes.

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

[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 carbon dioxide, 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, a solution method is also suitable, in which an alkali (such as NaOH or an amine) is reacted with CO2 to produce Na2CO3 or an amine carbonate, and then this is reacted with CaO to produce CaCO3.

[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 carbonates> 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, effective utilization, and carbon dioxide reduction.

[0070] The calcium-based carbonate compound preferably has an SiO2 content of 5% to 50% by mass, an Al2O3 content of 1% to 20% by mass, an Fe2O3 content of 0.5% to 15% by mass, and an average particle size of 1 μm to 50 μm as determined by laser diffraction.

[0071] The calcium-based carbonate compound preferably contains 5% to 50% by mass of SiO2, more preferably 8% to 48% by mass, and even more preferably 10% to 45% by mass. This makes it possible to improve the strength of the inorganic molded article containing the calcium-based carbonate compound.

[0072] The calcium-based carbonate compound preferably contains Al2O3 in an Al2O3 content of 1% to 20% by mass, more preferably 2% to 18% by mass, and even more preferably 3% to 15% by mass. This makes it possible to improve the strength of the inorganic molded article containing the calcium-based carbonate compound.

[0073] The calcium carbonate compound preferably contains 0.5% to 15% by mass of Fe2O3, more preferably 1% to 12% by mass, and even more preferably 1.5% to 10% by mass. 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 calcium-based carbonate compound preferably has an SO3 content of 0.5% to 10% by mass, more preferably 0.8% to 8% by mass, and even more preferably 1% to 6% by mass. This makes it easier to control the curing time of the inorganic molded article containing the calcium-based 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 is less than or equal to / g, and 7m 2 / g or more 150m 2 It is more preferable that it be less than or equal to / g, 10m 2 / g or more 100m 2 It is even more preferable that the amount 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] 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. The CO2 mainly originates 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 article) can be improved. The CO2 content in the calcium carbonate compound refers to the total content of CO2 in the CaO-containing composition and newly immobilized CO2.

[0079] The CO2 fixation rate in the calcium carbonate compound is preferable to be higher than the environmental standard, but 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 the value obtained by subtracting the CO2 content in the CaO-containing composition from the CO2 content in the calcium carbonate compound.

[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. Since the calcium-based carbonate compound contains SiO2 and other elements that contribute to hardening, it can be used in applications such as the inorganic molded articles and is therefore useful.

[0083] In light of the synthesis procedure, the aforementioned calcium carbonate compound is preferably a synthetic calcium carbonate compound. By using a synthetic calcium carbonate compound, which is a reaction product of a CaO-containing composition and carbon dioxide, as the calcium carbonate compound, carbon dioxide secondarily generated in industrial processes can be reused, contributing to a reduction in carbon dioxide emissions throughout the industrial process.

[0084] Furthermore, the present invention relates to a calcium carbonate compound containing CaCO3, wherein the SiO2 content is 5% by mass or more and 50% by mass or less, the Al2O3 content is 1% by mass or more and 20% by mass or less, the Fe2O3 content 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.

[0085] The calcium carbonate compound has a higher CaCO3 content from an environmental standpoint, but it is 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 article 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 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 the flue gas of a lime calcination furnace installed in close proximity to the calcium-based carbonate compound production plant, boilers, or waste incinerators. 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 carbonate compounds> The uses of the calcium carbonate compound are not particularly limited, but are suitable, for example, as a high-performance material for inorganic molded articles such as building materials, or as a filler for resins. The following describes how calcium carbonate compounds are used in inorganic molded articles.

[0088] <Inorganic molded material> The present invention relates to an inorganic molded article containing the calcium-based carbonate compound. The inorganic molded body containing the aforementioned calcium-based carbonate compound is a mixture of calcium carbonate and impurities such as SiO2, and is therefore useful because it improves 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). The applicable compositions and other details will be described below according to their intended use.

[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 plate preferably contains a hydraulic material, a siliceous material, a reinforcing fiber material, and a calcium-based carbonate compound.

[0092] (hydraulic material) Examples of the 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 types.

[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] (siliceous material) Examples of the siliceous materials include materials containing a large amount of SiO2, 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 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% to 55% by mass, more preferably 12% to 50% by mass, and even more preferably 15% to 45% by mass, based on the total amount of material constituting the molded board. If the content of the siliceous material is within the above range, it is possible to set the bending strength, bulk density, water absorption rate, dimensional stability, etc. of the molded board to the desired range. As the siliceous material, perlite, fly ash balloons, shirasu balloons, etc., have a unit volume mass of 0.5 g / cm³. 3 When incorporating the following lightweight aggregates, it is preferable to use other siliceous materials in combination so that the lightweight aggregate content is 20% by mass or less, based on the total amount of materials constituting the molded board, in order to prevent the bulk density from becoming too low and the strength, such as bending strength and peel strength, from weakening.

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

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

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

[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 ingredient) In addition to the aforementioned materials, the molded board can be blended with 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, depending on the purpose, in order to impart various functions. It is also possible to appropriately add recycled materials, such as crushed scraps generated during the processing of the molded board, to the material.

[0101] The bulk density of the molded plate is 0.7 g / cm³. 3 Preferably, it should be 0.8 g / cm³ or more. 3It 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 of manufacturing molded boards) The method for manufacturing the molded sheet 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 sheet can be obtained by molding a green sheet using these methods, then dewatering it by press or applying a pattern by embossing, and finally curing it at room temperature, with steam, or in an autoclave. Furthermore, it may be dried and, if necessary, shaped or painted.

[0103] (Uses of molded sheets) The use of the molded board is not particularly limited, and it can be suitably used as a performance maintenance material for wall materials, floor materials, roofing materials, various boards, exterior decorative members, interior and exterior finishing materials such as joinery, sealing materials, heat insulation materials, sound absorbing materials, waterproofing materials, etc. The molded board is preferably a cement-based molded board containing cementitious material, and a calcium silicate molded body is more preferable.

[0104] (Concrete structure) Concrete structures are composed of hardened bodies of hydraulic compositions. The hydraulic composition consists of a powder containing, in addition to a calcium-based carbonate compound, at least one of the following: blast furnace slag, expansive agent, slaked lime, quicklime, fly ash, and Portland cement. The calcium-based carbonate compound described above can be suitably used as the calcium-based 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] For the blast furnace slag mentioned above, 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 that conforms to JIS A6206 "Blast Furnace Slag for Concrete". Furthermore, the blast furnace slag preferably has a specific surface area of ​​2000 cm². 2 / g or more 10000cm 2 / g or less, more preferably 3500cm² 2 / g or more 7000cm 2 Use ingredients that are less than / g.

[0109] For the aforementioned expansive material, 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 total 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, quicklime specified in JIS R9001 "Industrial Lime" may 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 rapid-hardening Portland cement, ultra-rapid-hardening 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 should be 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] <Method for increasing the CO2 fixation rate of inorganic molded materials> The present invention relates to a method for increasing the CO2 fixation rate of an inorganic molded body using ultrafine pulverized water-granulated slag. The CaO-containing composition for producing the calcium-based carbonate compound obtained by using the ultrafine pulverized product of the granulated 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, which is useful for improving the fire resistance of the inorganic molded body using the same. In addition, the ultrafine pulverized product refers to granulated 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.

Example

[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 it does not exceed the gist. 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 matter, wet matter, 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 for use in 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 and weighed precisely. 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 weighed precisely, and the difference in mass before and after heating was determined 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 (% by mass). D is the mass loss (g). 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 pipette, heated and dissolved it. After cooling, transferred it to a 250 mL volumetric flask, added water to make up to 250 mL. From this, 20 mL was taken and transferred to a 50 mL volumetric flask, and water was added to make up to 50 mL to obtain the 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 atomic emission spectrometry (ICP-AES) apparatus (manufactured by Hitachi High-Technologies 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: 317.933nm Si: 251.612nm Fe: 238.204nm Al: 167.078nm S:182.034nm Finally, the mass percentage of each element was determined from the calculated amounts of each element, and the mass percentages of CaO, SiO2, Fe2O3, Al2O3, and SO3 were calculated by converting them to oxides.

[0122] (CO2 content) The reagents used for the measurement were prepared as follows. • 1 / 10N Barium Hydroxide Solution: 15.8g of barium hydroxide (octahydrate) was dissolved in ultrapure water to a total volume of 1000mL. After sealing the container 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: Dissolve 1 g of phenolphthalein in ethanol to make a total volume of 100 mL.

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

[0124] Using the measuring apparatus shown in Figure 1, the CO2 content (mass%) was determined by the following procedure. 20.0 mL of 1 / 10N barium hydroxide solution was placed in 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 placed in 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 operation for 90 minutes or more, the 100 mL medium bottle was removed from the apparatus and titrated directly with 1 / 10N hydrochloric acid standard solution. The same procedure was repeated without adding the sample to the 500 mL medium bottle to serve as a control. The CO2 content (mass%) was determined based on the following formula.

number

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

number

[0126] (BET specific surface area) The sample powder, pre-treated in a nitrogen gas atmosphere at approximately 130°C for approximately 30 minutes using an 8-stage preheating unit (MOUNTECH), was then measured for its BET specific surface area (m²) using a Macsorb HM Model-1208 (MOUNTECH) BET specific surface area analyzer by nitrogen gas adsorption. 2 The measurement ( / g) was taken.

[0127] (Average particle diameter determined by laser diffraction) A dispersion was prepared by placing 50 mL of ethanol into a 100 mL beaker, adding approximately 0.2 g of the sample powder to the same 100 mL beaker, and performing ultrasonic treatment for 3 minutes (UD-201, manufactured by Tommy Seiko Co., Ltd.). The dispersion was then analyzed using a 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 instrument (MiniFlex600-C, Rigaku Corporation) to identify and analyze the crystalline substances. It was confirmed that all of the obtained calcium-based carbonate compounds, as described later, contained calcite crystals.

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

number

[0130] (Formation rate of calcium-based carbonate compounds that contributed to CO2 fixation) The production rate E (mass%) of calcium-based 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) Double-sided tape was attached to the aluminum sample stage, and the sample powder was applied thereon by spreading 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) After filling an 8L capacity SUS container with baffles with 6L of water, 1.0 kg of dry-ground paper sludge calcination ash (manufactured by Marusumi Paper Co., Ltd., sample name: BF ash, average particle size 10 μm) was added to the container under stirring. The mixture was then heated to 40°C and stirred at 350 rpm using a stirrer equipped with a single-stage turbine blade. A pipe for exhaust gas extraction was connected to the exhaust outlet of a steam production boiler fueled by LNG, and the exhaust gas was drawn in using a test blower. A CO2 concentration meter (XP-3140, manufactured by Shin-Cosmos Electric Co., Ltd.) measured the CO2 concentration in the exhaust gas, which was 10% by volume. The exhaust gas was introduced into the aforementioned 8L capacity SUS container at a speed of 3.3 L / min using the test blower and allowed to react for 10 hours. Next, the filtered wet material was dried at 110°C for 12 hours and then pulverized to obtain a sample powder of calcium carbonate compound 1 (see Figure 2). For the analysis of the CaO-containing composition, a product dried at 110°C for 12 hours was used (the same applies to calcium-based carbonate compounds 2-5 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) A sodium carbonate aqueous solution was prepared by adding 894g of sodium carbonate reagent (manufactured by Wako Pure Chemical Industries: 99.8% purity) to a 20L capacity stainless steel container with baffles, pre-filled with 18L of water, while stirring. Meanwhile, CaO-containing composition 3 was prepared by placing 10 L of water and 1.7 kg of granulated slag (1.2 mm blast furnace slag fine aggregate (BFS1.2) of JIS A 5011-1:2018 "Slag aggregate for concrete - Part 1") into a 20 L capacity pot mill filled with 5 kg of 8 mm diameter zirconia balls, and wet grinding at a rotation speed of 90 rpm for 24 hours. The ground slurry was removed from the pot mill, and 6 L of this ground slurry was placed into a 30 L capacity polyethylene container. Under stirring at 25°C, 18 L of the aforementioned sodium carbonate aqueous solution was added all at once, and the reaction was carried out by continuing stirring for about 30 minutes. After that, it was filtered, washed with about 5 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-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-based 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 a 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 mesh sieve. The material under 4 mm was then 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 Example 1-1 and Comparative Example 2-1) Except for using granulated slag that has not undergone wet grinding (1.2 mm blast furnace slag fine aggregate (BFS1.2) as specified in JIS A 5011-1:2018 "Slag aggregate for concrete - Part 1") (CaO-containing composition 6), the same procedure as for calcium-based carbonate compound 3 was followed to obtain a sample powder of calcium-based carbonate compound 6 (see Figure 5). 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 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) from cement compositions) The types and amounts of calcium carbonate compounds shown in Table 3 were added to 1600g 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 listed in the table over about 20 seconds and mixed with the aforementioned 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 manually 10 times with a stirring rod (AS ONE Corporation, "Stirring Rod (POM) φ10×300mm"). 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. In addition, the blank (Comparative Example 3-1) had 400g of fine aggregate (crushed sand; less than 5mm in size) instead of calcium carbonate. 400 mL of the prepared cement milk was poured into a cylindrical polyethylene bag (approximately 50 mm in diameter x 550 mm in length x 0.05 mm in thickness) up to the mark. 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 allow the contents to harden, thereby 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) were evaluated as follows. 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) In accordance with JIS A 5430:2008 (Apparent Density Test), the density (g / cm³) of the molded cement composition (concrete structure) obtained was determined. 3 ) was measured.

[0143] (Compression strength test) The compressive strength (N / mm²) of the molded concrete structure (concrete building) obtained from the cement composition was determined in accordance with JIS A 1108:2018 (Compression Test Method for Concrete). 2 ) was measured. While a higher compressive strength is preferable for the molded body (concrete structure) of the cement composition, 32 N / mm² is considered acceptable. 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 products (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 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 (not used in Comparative Example 4-1). The raw material slurry was divided and placed into a filter lined with felt, and laminated boards (28mm long x 24mm short x 14mm thick) were produced by suction filtration using a vacuum pump. The laminated boards were removed from the filter and dewatered by pressing. The thickness after pressing was 13mm. After autoclave curing (curing pressure (gauge pressure) 9kgf; curing time 12hr), the pressed body was dried in a dryer (105℃) for 24hr. Both sides were polished with a sander to adjust the thickness to 12mm, and an inorganic molded body was obtained.

[0146] <Evaluation of inorganic molded products> 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 materials (building materials)) The CO2 fixation rate I (mass%) in inorganic molded products (building materials) was calculated using the following formula.

number

[0148] (Bulk density) The bulk density of the inorganic molded material (building material) 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 preheating was performed to 902°C, after which the heating was temporarily stopped. (2) The test specimen was replaced after the heated side had cooled to 200°C or below. (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 to secure it. (4) Start heating and leave it for a predetermined time (45 minutes), and record the temperature of the heating surface and the back surface using 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 specimens were 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.

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 size of the CaO-containing compositions in the examples was smaller than that of the comparative examples. Furthermore, the CO2 fixation rate in the calcium carbonate compound, the production rate of the calcium carbonate compound that contributed to the CO2 fixation, and the CaCO3 content in the calcium carbonate compound were all higher than those of the comparative examples.

[0156] The results in Table 3 above confirm that the example using the desired calcium-based carbonate compound can simultaneously satisfy the desired properties in terms of CO2 fixation rate, density, and compressive strength.

[0157] As shown in Table 4 above, the example using calcium-based carbonate compound was found to simultaneously satisfy the desired properties in terms of CO2 fixation rate, heating surface shrinkage, and back surface temperature rise, compared to the comparative example.

Claims

1. The free CaO content is 15% by mass or more and less than 50% by mass. SiO ２ The content is 5% by mass or more and 50% by mass or less. Al ２ O ３ The content is 1% by mass or more and 20% by mass or less. Fe ２ O ３ The content is 0.5% by mass or more and 15% by mass or less. A CaO-containing composition having an average particle diameter 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 m 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. A CaO-containing composition according to claim 1, which is for recycling.

7. A preparation step for preparing the CaO-containing composition according to any one of claims 1 to 6, A method for producing a calcium carbonate compound, comprising 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. SiO ２ The content of which is 5% by mass or more and 50% by mass or less, Al ２ O ３ The content is 1% by mass or more and 20% by mass or less. Fe ２ O ３ The content is 0.5% by mass or more and 15% by mass or less. The calcium-based carbonate compound according to claim 12, wherein the average particle size determined by laser diffraction is 1 μm or more and 50 μm or less.

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 m 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. A calcium-based carbonate compound according to claim 12, comprising calcite.

18. A 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 described in 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 is 5% by mass or more and 50% by mass or less. Al ２ O ３ The content is 1% by mass or more and 20% by mass or less. Fe ２ O ３ The content is 0.5% by mass or more and 15% by mass or less. A calcium carbonate compound having 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 m 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. A calcium-based carbonate compound according to claim 21, comprising calcite.

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

28. A 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 inorganic molded body described in claim 27 is CO ２ Methods to increase the fixation rate.

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