Calcium-based carbonate compound and inorganic molded body

Abstract

Provided are: a calcium-based carbonate compound capable of improving the strength of a molded body while maintaining the fluidity of a mixture in a production process; and an inorganic molded body. This cubic calcium-based carbonate compound has a phosphorus atom content of at most 1,000 ppm and a sulfur atom content of at least 100 ppm. The average particle diameter of the calcium-based carbonate compound measured by a laser diffraction method is preferably 2-25 μm. The BET specific surface area of the calcium-based carbonate compound is preferably 0.3 m2 / g to 3 m2 / g.

Description

Calcium carbonate compounds and inorganic moldings

[0001] The present invention relates to a calcium carbonate compound and an inorganic molded body.

[0002] Inorganic molded bodies are molded bodies that are mostly composed of inorganic substances such as hydraulic materials and siliceous materials, and because they have properties such as fire resistance, light weight, high strength, and workability, they are widely used for exterior wall materials, roof underlayment materials, eaves ceiling materials, etc. of houses, etc. They are also widely used for foundations, walls, pillars, floors, etc. of buildings that require strength and fire resistance.

[0003] As a technique for increasing strength, which is one of the important properties required for inorganic molded bodies, a technique of compounding needle-shaped calcium carbonate has been proposed (Japanese Patent No. 6898926).

[0004] Patent No. 6898926

[0005] However, even with the above techniques, the strength of the inorganic molded body obtained may decrease, and the fluidity of the mixture of raw materials during the manufacturing process may decrease, which may ultimately reduce the working efficiency of the entire manufacturing process.

[0006] An object of the present invention is to provide a calcium carbonate compound and an inorganic molded body that can improve the strength of the molded body while maintaining the fluidity of the mixture during the manufacturing process.

[0007] As a result of extensive research, the present inventors have found that the above-mentioned problems can be solved by the following configuration, and have thus completed the present invention.

[0008] In one embodiment, the present invention relates to a cubic calcium carbonate compound having a phosphorus atom content of 1000 ppm or less and a sulfur atom content of 100 ppm or more.

[0009] As a result of investigations, the present inventors have newly discovered that, as factors in forming needle-like or rod-like shapes (hereinafter collectively referred to as "needle-like shapes, etc.") with high aspect ratios during crystal growth of calcium carbonate compounds, phosphorus atoms act as a factor promoting the formation of needle-like shapes, etc., and sulfur atoms act as a factor inhibiting the formation of needle-like shapes, etc. The calcium carbonate compounds have phosphorus atom and sulfur atom contents within specific ranges, so that the shape can be efficiently controlled to a cubic shape.

[0010] On the other hand, in the field of inorganic moldings, it is widely known to use needle-shaped or fibrous reinforcing materials such as needle-shaped calcium carbonate to increase the strength of inorganic moldings. However, increasing the amount of needle-shaped reinforcing material to further improve strength reduces the fluidity of the mixture as mentioned above, so there is a trade-off between improving strength and maintaining fluidity. After extensive research, the present inventors unexpectedly found that a cubic calcium carbonate compound can improve the strength of the resulting inorganic molding while maintaining the fluidity of the mixture during the manufacturing process.

[0011] The present invention has been completed by developing these new findings.

[0012] Although the reason why the calcium carbonate compound can achieve both fluidity and strength is unclear, it is speculated as follows. Because the calcium carbonate compound is cubic, the shear stress in the mixture is reduced, and the viscosity-increasing effect is smaller than that of needle-shaped particles. As a result, the fluidity of the mixture can be maintained. Furthermore, the cubic shape improves the strength and density of the calcium carbonate compound itself, and its isotropy (non-orientation) in the mixture allows for homogeneous dispersion or homogeneous packing, thereby improving the strength of the inorganic molded product. Furthermore, the viscosity of a mixture containing needle-shaped particles is high, making it difficult for air bubbles to escape. If the final product is obtained with air bubbles remaining, the strength of the final product may be reduced. It is speculated that the cubic calcium carbonate compound, due to its fluidity and isotropy, facilitates the escape of air bubbles in the mixture, thereby preventing or improving strength reduction.

[0013] As used herein, the term "cubic" does not refer to a regular cubic shape, but rather refers to a shape that can be roughly regarded as a cube. For example, even if one or more vertices of a cube are rounded or missing, the cube is still cubic if the cube can be restored by filling in the missing vertices. Furthermore, the target shape is cubic if the length of one side of the target shape is between 50% and 150% of the length of the other side. Furthermore, the shape of one side of the target shape is not limited to a square, and may be any shape, such as a trapezoid, a rhombus, or a rectangle with four sides of different lengths, as long as the ratio of the lengths of the two sides is satisfied. In addition, not all particles constituting the calcium carbonate compound are necessarily cubic; the calcium carbonate compound is cubic if the proportion of cubic particles among all particles is the largest.

[0014] In this specification, the term "calcium-based carbonate compound" refers to a compound containing calcium carbonate as a main component, which is a concept that allows the inclusion or coexistence of other subcomponents that may be incorporated during the manufacturing process, etc. The calcium carbonate content in the calcium-based carbonate compound is preferably 90% by mass or more. The calcium carbonate content in the calcium-based carbonate compound can be suitably measured by the ethylenediaminetetraacetic acid disodium titration method.

[0015] <Ethylenediaminetetraacetic acid disodium titration method> 1 g of calcium carbonate compound (dried for 2 hours at 105°C) was weighed as a sample and suspended in 50 mL of water. 10 mL of hydrochloric acid (a 1:1 mixture of concentrated hydrochloric acid and water by volume) was added and heated to dissolve. After cooling, the suspension was transferred to a 250 mL volumetric flask and made up to the same volume with water. A 5.00 mL aliquot was taken from this and water was added to bring the total volume to approximately 50 mL. 5 mL of buffer solution (a 1,000 mL solution prepared by dissolving 500 g of potassium hydroxide in water) was added, followed by commercially available Dotite NN diluted powder. The titration was terminated when the solution changed color from red to blue. The calcium carbonate content (%) was calculated using the following formula:

[0016] (In the formula, f is the factor of the titration reagent. The factor is determined by standardization with the titration reagent using a BT indicator. V is the amount of titration reagent consumed (mL). W is the amount of sample taken (0.02 g of calcium carbonate compound).)

[0017] In one embodiment, the calcium carbonate compound has an average particle size of 2 μm or more and 25 μm or less as measured by a laser diffraction method. In one embodiment, the calcium carbonate compound has a BET specific surface area of ​​0.3 m ２ / g or more 3m ２ In one embodiment, the apparent specific gravity of the calcium carbonate compound is preferably 1 g / mL or more and 2 g / mL or less. By satisfying these properties alone or in combination, both fluidity and strength can be achieved at a higher level.

[0018] In one embodiment, the calcium carbonate compound can have a flow time through a P funnel of 7 seconds or more and 10 seconds or less, thereby enabling the calcium carbonate compound to exhibit good fluidity.

[0019] In one embodiment, the magnesium content in the calcium-based carbonate compound may be 1000 ppm or more. The magnesium content in the calcium-based carbonate compound varies depending on the raw material, manufacturing method, etc. For example, when a raw material relatively rich in magnesium (seawater, etc.) is used, the magnesium content in the calcium-based carbonate compound will be 1000 ppm or more. When a raw material relatively low in magnesium (the supernatant liquid of concrete sludge, etc.) is used, the magnesium content in the calcium-based carbonate compound will be less than 1000 ppm.

[0020] In one embodiment, the calcium carbonate compound is preferably a synthetic calcium carbonate compound in terms of production efficiency and shape controllability.

[0021] In another embodiment, the present invention relates to an inorganic molded body containing the calcium carbonate compound.

[0022] By applying a cubic calcium carbonate compound to an inorganic molded body, it is possible to efficiently obtain a strong inorganic molded body while maintaining fluidity and good workability during the manufacturing process.

[0023] 1 shows SEM photographs of the calcium carbonate compound of Example 1-1 of the present invention, and SEM photographs of the calcium carbonate compound of Comparative Example 1-1 of the present invention.

[0024] The calcium carbonate compound and inorganic molded body according to one embodiment of the present invention will be described below, but the present invention is not limited to these embodiments.

[0025] <Calcium-Based Carbonate Compound> The calcium-based carbonate compound according to this embodiment is cubic. In the calcium-based carbonate compound, the phosphorus atom content is 1000 ppm or less and the sulfur atom content is 100 ppm or more.

[0026] In the calcium carbonate compound, the phosphorus atom content is not particularly limited as long as it is 1000 ppm or less. The phosphorus atom content is preferably 500 ppm or less, and more preferably 100 ppm or less. On the other hand, the lower the phosphorus atom content, the better, but it may be present at about 1 ppm. By setting the phosphorus atom content, which is one factor in the acicular formation of calcium carbonate compounds, to the above-mentioned predetermined amount, cubic calcium carbonate compounds can be efficiently formed.

[0027] In the calcium carbonate compound, the sulfur atom content is not particularly limited as long as it is 100 ppm or more. It is preferably 500 ppm or more, and more preferably 1000 ppm or more. The sulfur atom content is preferably 10000 ppm or less, and more preferably 5000 ppm or less. By setting the sulfur atom content to the above-mentioned predetermined amount, an inhibitory effect on acicular formation and the like can be exerted, and a cubic calcium carbonate compound can be efficiently obtained.

[0028] The calcium carbonate compound has an average particle size of preferably 2 μm to 25 μm, more preferably 4 μm to 22 μm, and even more preferably 6 μm to 18 μm, as measured by a laser diffraction method. This allows the fluidity of the mixture containing the calcium carbonate compound to be favorably maintained. In addition, the strength of the resulting inorganic molded body can be further improved.

[0029] The BET specific surface area of ​​the calcium carbonate compound is 0.3 m ２ / g or more 3m ２ / g or less, and ２ / g or more 2.6m ２ / g or less is more preferable, and 0.5m ２ / g or more 2.4m ２ / g or less. This makes it possible to favorably maintain the fluidity of the mixture containing the calcium carbonate compound, and also improve the dispersibility of the calcium carbonate compound. In addition, the strength of the resulting inorganic molded body can be further improved.

[0030] The apparent specific gravity of the calcium carbonate compound is preferably 1.00 g / mL or more and 2.00 g / mL or less, more preferably 1.05 g / mL or more and 1.80 g / mL or less, and even more preferably 1.10 g / mL or more and 1.60 g / mL or less. This allows the fluidity of the mixture containing the calcium carbonate compound to be favorably maintained. In addition, the density and strength of the calcium carbonate compound are increased, thereby further improving the strength of the resulting inorganic molded body.

[0031] The flow time of the calcium carbonate compound through the P funnel is preferably 7 to 10 seconds, more preferably 7.5 to 9.8 seconds, and even more preferably 8 to 9.5 seconds. The calcium carbonate compound is cubic, so it can exhibit excellent fluidity.

[0032] The magnesium content in the calcium carbonate compound may be 1,000 ppm or more, 5,000 ppm or more, or 10,000 ppm or more. The upper limit of the magnesium content is about 50,000 ppm, although this depends on the raw materials, production method, etc.

[0033] The crystal structure of the calcium carbonate compound may be a calcite type, an aragonite type, or a combination thereof. In order to obtain a cubic calcium carbonate compound, it is preferable that the calcite type crystal structure is relatively abundant and the aragonite type crystal structure is relatively rare.

[0034] In the X-ray diffraction measurement of the calcium carbonate compound, the peak intensity I of aragonite ａ Calcite peak intensity I ｃ Ratio to I ａ / I ｃ is preferably 0.1 or less, more preferably 0.08 or less, and even more preferably 0.06 or less, whereby a cubic calcium carbonate compound can be efficiently obtained.

[0035] The calcium carbonate compound is preferably a synthetic calcium carbonate compound in terms of production efficiency and shape controllability.

[0036] (Method for producing calcium carbonate compound) The method for producing a calcium carbonate compound is not particularly limited, and a known production method can be adopted. Typically, a solution method can be preferably adopted in which a carbonate (carbonate ion) is brought into contact with calcium (calcium ion) from seawater or the like to carry out salt exchange to produce a calcium carbonate compound. Ca ２＋ +CO ３ ２－ →CaCO ３ (A)

[0037] As the salt of carbonate ion used in reaction formula (A), alkali metal salts (Li, Na, K) and alkaline earth metal salts (Mg, Sr, but excluding Ca) are used, and among them, alkali metal salts are preferably used. Among them, Na salt (sodium carbonate) is preferred in terms of versatility and cost.

[0038] The carbonate may be brought into contact with seawater or the like by adding an aqueous solution or slurry of the carbonate to seawater or the like, or by adding seawater or the like to the aqueous solution or slurry. The addition is preferably carried out all at once, since the desired cubic calcium carbonate compound can be efficiently obtained.

[0039] Seawater may be directly drawn from a nearby ocean, or may be filtered before use. Drawing seawater is not limited to nearby waters, and it may be taken from any location where seawater is available. Calcium-rich seawater, which is produced when magnesium hydroxide is removed from seawater, may also be used.

[0040] The amount of carbonate salt to be added is not particularly limited as long as it is set so as to obtain the amount of carbonate ions necessary for the reaction with the amount of calcium ions in seawater, etc., according to the above reaction formula (A). Although the amount of calcium ions and the amount of carbonate ions are preferably equimolar, the molar ratio of the amount of carbonate ions to the amount of calcium ions may be within a range of 50 to 200%.

[0041] The salt exchange reaction caused by contact of carbonate with seawater or the like proceeds relatively quickly. The reaction time may be set to a time sufficient for the salt exchange reaction to proceed sufficiently, and may be set to 1 second or more, preferably 1 minute to 60 minutes, and more preferably 5 minutes to 50 minutes.

[0042] The produced calcium carbonate compound may be filtered and dried to obtain a powder, or may be used as a calcium carbonate compound source in the form of a slurry or cake without being filtered and dried.

[0043] <Uses of calcium-based carbonate compounds> The uses of calcium-based carbonate compounds are not particularly limited. For example, they are suitable as high-performance additives for inorganic molded bodies, such as building materials and architectural structures, and fillers for resins. Hereinafter, embodiments in which calcium-based carbonate compounds are used in inorganic molded bodies will be described.

[0044] <Inorganic Molded Body> The inorganic molded body is not particularly limited, and representative examples include molded boards for building materials, concrete structures (concrete molded bodies), etc. Applicable compositions and the like will be described in detail below depending on the application.

[0045] (Molded Board for Building Material) The molded board preferably contains a hydraulic material, a siliceous material, a reinforcing fiber material, and a calcium carbonate compound.

[0046] (Hydraulic Materials) Examples of hydraulic materials include cementitious materials, gypsum, lime, slag, etc. 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 alone or in combination of two or more.

[0047] The content of the hydraulic material is preferably 5% by mass or more and 45% by mass or less, more preferably 8% by mass or more and 42% by mass or less, and even more preferably 10% by mass or more and 40% by mass or less, based on the total amount of materials constituting the molded board. By setting the content of the hydraulic material within the above range, it is possible to improve the physical properties of the molded board, such as bending strength and peel strength, and to suppress an increase in the bulk density of the molded board, thereby improving workability during construction.

[0048] (Silicate Material) Examples of siliceous materials include silica sand, silica powder, silica fume, fly ash, diatomaceous earth, layered silicates (e.g., mica, talc, kaolin, bentonite), wollastonite, lightweight aggregates (e.g., fly ash balloons, perlite, shirasu balloons, glass foams, etc.), and other SiO ２ These siliceous materials can be used alone or in combination of two or more. Talc, mica, and wollastonite can also be used as reinforcing fiber materials, which will be described later.

[0049] The content of the siliceous material is preferably 10% by mass or more and 55% by mass or less, more preferably 12% by mass or more and 50% by mass or less, and even more preferably 15% by mass or more and 45% by mass or less, based on the total amount of materials constituting the molded board. If the content of the siliceous material is within the above range, it becomes possible to set the bending strength, bulk specific gravity, water absorption rate, dimensional stability, etc. of the molded board within the desired range. In addition, as the siliceous material, perlite, fly ash balloons, shirasu balloons, etc., having a unit volume mass of 0.5 g / cm are preferred. ３ When mixing the following lightweight aggregates, in order to prevent the bulk density from becoming too light and weakening strength such as bending strength and peel strength, it is preferable to use other siliceous materials in combination so that the content of lightweight aggregate is 20 mass% or less, based on the total amount of materials constituting the molded board.

[0050] (Reinforcing Fiber Material) Examples of reinforcing fiber materials that can be used include pulps 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. These reinforcing fiber materials can be used alone or in combination of two or more.

[0051] In order to improve the strength and toughness of the molded board, the content of the reinforcing fiber material is preferably 2% by mass or more and 30% by mass or less, more preferably 3% by mass or more and 26% by mass or less, and even more preferably 4% by mass or more and 22% by mass or less, based on the total amount of materials constituting the molded board. By setting the content of the reinforcing fiber material within the above range, it is possible to exhibit a sufficient reinforcing effect while suppressing the protrusion of fibers on the surface of the molded board, thereby improving smoothness. When an inorganic reinforcing fiber material having an average length of 1 mm to 50 mm is blended as the reinforcing fiber material, it is preferable to use other reinforcing fiber materials in combination so that the content is 10% by mass or less, based on the total amount of materials constituting the molded board, in order to improve the smoothness of the molded board.

[0052] (Calcium-Based Carbonate Compound) As the calcium-based carbonate compound, the calcium-based carbonate compounds described above can be suitably used.

[0053] The content of the calcium carbonate compound is preferably 5% by mass or more and 60% by mass or less, more preferably 8% by mass or more and 55% by mass or less, and even more preferably 12% by mass or more and 50% by mass or less, based on the total amount of materials constituting the molded board. By blending the low thermal conductive calcium carbonate compound in an amount within the above range, the strength and fire resistance of the molded board can be improved.

[0054] (Optional Components) In addition to the above materials, various materials such as hollow resin bodies, wood chips, wood flour, resin powder, antifoaming agents, flocculants, water repellents, thickeners (methyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, etc.), dispersants, etc. can be blended into the molded board depending on the purpose in order to impart various functions. It is also possible to appropriately add recycled materials obtained by crushing scraps generated during the processing of the molded board.

[0055] The bulk density of the molded plate is 0.7 g / cm ３ 2.0g / cm or more ３ It is preferable that the density is 0.8 g / cm or less. ３ 1.8g / cm or more ３ More preferably, it is 0.9 g / cm or less. ３ 1.6g / cm or more ３ It is even more preferable that:

[0056] (Method for manufacturing molded plate) The method for manufacturing the molded plate according to this embodiment is not particularly limited, and commonly used methods such as papermaking, extrusion molding, flow-on molding, casting, and press (compression) molding can be used. The molded plate can be obtained by subjecting a green sheet molded by these methods to press dehydration or patterning by embossing or the like, followed by curing at room temperature, steam curing, autoclave curing, or the like. The molded plate may then be dried and, if necessary, shaped or painted.

[0057] (Uses of molded board) The uses of the molded board are not particularly limited, and it can be suitably used as a performance maintaining material for wall construction materials, flooring materials, roofing materials, various boards, external decorative members, interior and exterior finishing materials such as fittings, sealing materials, heat insulating materials, sound absorbing materials, waterproofing materials, etc. The molded board is preferably a cement-based molded board containing a cementitious material, and more preferably a calcium silicate molded body.

[0058] (Concrete Structure) The concrete structure is composed of a hardened body of a hydraulic composition. The hydraulic composition is made of a powder containing a calcium carbonate compound and at least one of blast furnace slag, an expansive agent, slaked lime, quicklime, fly ash, and Portland cement. As the calcium carbonate compound, the calcium carbonate compounds described above can be suitably used.

[0059] In addition to the hydraulic composition, aggregates such as sand and gravel, chemicals such as chemical admixtures for concrete, and fiber materials made of metals or polymeric materials may be blended to form a hydraulic composition mixture.

[0060] The hardened hydraulic composition is obtained by hardening a paste obtained by kneading the hydraulic composition with water, and the hardened hydraulic composition mixture is obtained by hardening a mixture (equivalent to fresh mortar or fresh concrete) obtained by kneading the hydraulic composition mixture with water, and corresponds to mortar or concrete.

[0061] The ratio of the calcium carbonate compound in the powder (the ratio of the calcium carbonate compound to the cement) is within a range of 1 mass % to 60 mass %, preferably 3 mass % to 50 mass %, and more preferably 5 mass % to 40 mass %.

[0062] It is desirable to use ground granulated blast furnace slag used in JIS (Japanese Industrial Standards) R5211 "blast furnace cement" or ground granulated blast furnace slag conforming to JIS A6206 "blast furnace slag for concrete." In addition, the blast furnace slag should have a specific surface area of ​​2000 to 10000 cm. ２ / g, preferably 3500 to 7000 cm ２ It is desirable to use one having a saturation of 0.15 to 0.25 g.

[0063] The expansive material may be, for example, an expansive material specified in JIS A6202 "Expansive materials for concrete." The expansive material is preferably added in an amount of 2 to 9 mass % based on the total amount of the hydraulic composition.

[0064] For example, slaked lime specified in JIS R9001 "Industrial Lime" may be used. Furthermore, quicklime becomes slaked lime when it comes into contact with water, so quicklime specified in JIS R9001 "Industrial Lime" may be used instead of slaked lime. In this case, it is advisable to correct the amount of water required to convert quicklime into slaked lime. For example, fly ash conforming to JIS A6201 "Fly ash for concrete" may be used.

[0065] Ordinary Portland cement is used as the Portland cement, but other types of Portland cement such as high-early-strength Portland cement, ultra-high-early-strength Portland cement, moderate-heat Portland cement, low-heat Portland cement, and sulfate-resistant Portland cement, as specified in JIS R5210 "Portland cement," and JIS R5214 "Ecocement" can also be used.

[0066] When the hydraulic composition contains Portland cement, the proportion of Portland cement in the powder other than the calcium carbonate compound is 70% by mass or less, and preferably 30% by mass or less.

[0067] Furthermore, when Portland cement and blast furnace slag or fly ash are used, the components may be pre-mixed, for example, JIS R5211 "blast furnace cement" or, for example, JIS R5213 "fly ash cement," and these may be used alone or in combination.

[0068] Since the calcium carbonate compound having the above characteristics is used, the hydraulic composition and the hydraulic composition mixture exhibit good fluidity, and the hardened concrete produced from the composition can exhibit excellent compressive strength.

[0069] The density of the concrete structure is 0.7 g / cm ３2.0g / cm or more ３ It is preferable that the density is 0.8 g / cm or less. ３ 1.8g / cm or more ３ More preferably, it is 0.9 g / cm or less. ３ 1.6g / cm or more ３ It is even more preferable that:

[0070] The present invention will be described in detail below using examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention. Measurements and evaluations of physical properties, etc. were carried out as follows.

[0071] <Evaluation of calcium carbonate compounds> The calcium carbonate compounds obtained in each production example were analyzed as follows. The analytical results are shown in Table 1 and Figures 1 and 2.

[0072] (1) BET Specific Surface Area A sample powder was pretreated in a nitrogen gas atmosphere at about 130°C for about 30 minutes using an 8-tube preheat unit (manufactured by MOUNTECH Co., Ltd.), and the BET specific surface area (m ２ / g) was measured.

[0073] (2) Average particle size by laser diffraction method 50 mL of ethanol was placed in a 100 mL beaker, and about 0.2 g of the sample powder was placed in the 100 mL beaker. The mixture was subjected to ultrasonic treatment (UD-201, manufactured by Tomy Seiko Co., Ltd.) for 3 minutes to prepare a dispersion. This dispersion was measured using a laser diffraction particle size distribution analyzer (Microtrac HRA Model 9320-X100, manufactured by Nikkiso Co., Ltd.) to determine the volumetric D ５０ The value was measured as the average particle diameter (μm).

[0074] (3) Apparent Specific Gravity The apparent specific gravity of the sample powder was measured in accordance with JIS K6220.

[0075] (4) Contents of Phosphorus, Sulfur, and Magnesium Atoms <ICP-AES Method> 0.2 g of calcium carbonate compound was weighed as a sample, moistened with water, and 10 mL of hydrochloric acid (a 1:1 volumetric mixture of concentrated hydrochloric acid and water) was added using a dispenser. The mixture was then heated and dissolved. After cooling, the mixture was transferred to a 250 mL volumetric flask and diluted to 250 mL with water. 20 mL of this solution was then transferred to a 50 mL volumetric flask, and water was added to 50 mL to prepare the sample solution for measurement. Separately, 20 mL of the aqueous solution diluted to 250 mL was transferred to a 50 mL volumetric flask, and standard solutions of each element (phosphorus, sulfur, and magnesium) were added as desired to prepare standard solutions for calibration curves with different concentrations. 1000 ppm atomic absorption standard solutions (commercially available) were used as the standard solutions for each element.

[0076] The calibration standard solutions containing different concentrations of each element added and the sample solution for measurement were placed in the autosampler of an inductively coupled plasma atomic emission spectrometry (ICP-AES) device (Hitachi High-Tech Science Corporation, "SPECTROBLUE FMS36 Model"), and the amount of magnesium atoms (ppm) was measured under the following conditions. <Measurement conditions> High frequency 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 Liquid type: Aqueous solution Number of integrations: 3 Sample order: For each sample Measurement method: Standard addition method Calibration curve weighting: None Measurement wavelengths: Phosphorus atom 177.495 nm, sulfur atom 182.034 nm, magnesium atom 279.553 nm

[0077] (5) 46° (aragonite) peak intensity I by XRD measurement ａ 29° (calcite) peak intensity I ｃ The sample powder was pressed and fixed onto a predetermined sample stage with a spatula, and then measured using an XRD device (MiniFlex600-C manufactured by Rigaku Corporation) to perform an identification analysis as a crystalline substance. Note that, at a measurement angle 2θ, the peak appearing at approximately 29° is the main peak of calcite, and the peak appearing at approximately 46° is the main peak of aragonite. From this, the 46° (aragonite) peak intensity I ａ29° (calcite) peak intensity I ｃ Ratio to (I ａ / I ｃ ) was sought.

[0078] (6) Scanning Electron Microscope Observation Double-sided tape was attached to an aluminum sample stage, and the sample powder was applied to the tape by tracing it with a spatula. After platinum deposition, particle images of the sample powder were photographed at 2,000 magnifications using a scanning electron microscope (FE-SEM: S-4700 manufactured by Hitachi, Ltd.). Figures 1 and 2 show SEM photographs of the examples and comparative examples.

[0079] <Production of calcium-based carbonate compound> [Example 1-1] Calcium-based carbonate compound (cubic) Sodium carbonate was prepared by adding 8510 g of sodium carbonate reagent (manufactured by Wako Pure Chemical Industries, Ltd.: purity 99.8%) to a 220 L SUS vessel equipped with a baffle and containing 100 L of water under stirring. ２＋ The calcium carbonate solution (content: 0.25 g / dL) was placed in a 2000 L polyethylene container, and 100 L of the above-mentioned aqueous sodium carbonate solution was added all at once while stirring at 25°C. The reaction was continued for about 30 minutes, after which the solution was filtered, washed with about 5 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 a calcium carbonate compound.

[0080] Example 1-2 Calcium-based carbonate compound (cubic shape) A sample powder of calcium-based carbonate compound was obtained by the same procedure as in Example 1-1, except that 12.7 kg of magnesium chloride hexahydrate was added to 1,000 L of seawater from which magnesium hydroxide had been removed under stirring, and then 100 L of the aforementioned aqueous sodium carbonate solution was added all at once.

[0081] [Example 1-3] Calcium-based carbonate compound (cubic) To 100 L of seawater from which magnesium hydroxide had been removed, 10 L of the aforementioned sodium carbonate aqueous solution was added all at once under stirring, and stirring was continued for approximately 30 minutes. Using this post-reaction liquid as a seed, 100 L of seawater from which magnesium hydroxide had been removed was added, and 10 L of the aforementioned sodium carbonate aqueous solution was added all at once under stirring, and stirring was continued for approximately 30 minutes. This series of operations was repeated a total of 10 times. Apart from these operations, the same operations as in Example 1-1 were carried out to obtain a sample powder of a calcium-based carbonate compound.

[0082] Comparative Example 1-1 Calcium-Based Carbonate Compound (Needle-Shaped) 6,980 g (calculated as CaO) of commercially available slaked lime powder (Yoshimi Lime Industry Co., Ltd., Best Industrial Slaked Lime), 630 g of aragonite seed crystal powder, and 3,000 g of disodium hydrogen phosphate dodecahydrate were prepared and each was charged with stirring into a 220 L SUS vessel equipped with a baffle and pre-filled with 180 L of water to prepare a mixed slurry of the raw materials. The mixture was then heated to 70°C and stirred at that temperature using a stirrer equipped with one turbine blade at a rotation speed of 150 rpm. A flue gas extraction pipe was connected to the exhaust outlet of an LNG-fueled steam production boiler, and a test blower was used to draw in the exhaust gas. ２ When measured using a concentration meter (XP-3140 manufactured by New Cosmos Electric Co., Ltd.), CO ２ The concentration was 10% by volume. The exhaust gas was introduced into the aforementioned 220-liter SUS vessel using a test blower at a rate of 100 L / min, and the reaction was carried out for 7 hours. The mixture was then filtered, washed with approximately five times the amount of water relative to the solid content, dried at 110°C for 24 hours, and pulverized to obtain a sample powder of a calcium carbonate compound.

[0083]

[0084] <Evaluation> Using the obtained calcium carbonate compound, the P funnel flow time was measured, and a cement molded body was produced and a compressive strength test was carried out. The results are shown in Table 3.

[0085] (Preparation of cement milk 1) 2 kg of cement ("ordinary Portland cement (N)" manufactured by Tokuyama Corporation) was added to 1600 mL of water over a period of about 20 seconds, and mixed with a stirrer ("Labo Stirrer (LR500B)" manufactured by Yamato Scientific Co., Ltd.) for 3 minutes from the start of addition. Stirring was stopped and the mixture was allowed to stand for 3 minutes, after which it was manually stirred 10 times with a stirring rod ("Stirring rod (POM) φ10 × 300 mm" manufactured by AS ONE Corporation) to prepare cement milk 1.

[0086] (Preparation of Cement Milks 2 to 7) The calcium carbonate compounds of Example 1-1 and Comparative Example 1-1 of the types and amounts shown in Table 2-1 below were added to 1600 mL of water, and after manual stirring with the stirring rod for about 30 seconds, the mixture was stirred at 400 rpm using the stirrer. 2 kg of cement (Tokuyama Corporation, "Ordinary Portland Cement (N)") was added to this mixture over about 20 seconds, and mixed with the stirrer for 3 minutes from the start of addition. Stirring was stopped and the mixture was allowed to stand for 3 minutes, after which cement milks 2 to 7 were prepared by manually stirring 10 times with the stirring rod.

[0087]

[0088] (Preparation of cement milks 8 to 10) Cement milks 8 to 10 were prepared in the same manner as for preparing cement milks 2 to 7, except that the calcium carbonate compound of Example 1-2 was used in the type and amount shown in Table 2-2 below.

[0089]

[0090] (Preparation of cement milks 11 to 13) Cement milks 11 to 13 were prepared in the same manner as for preparing cement milks 2 to 7, except that the calcium carbonate compounds of Examples 1-3 were used in the types and amounts shown in Table 2-3 below.

[0091]

[0092] (P funnel flow time test method) The P funnel flow time was measured in accordance with "Test method for fluidity of injection mortar for prepacked concrete (method using P funnel)" (JSCE-F521-1999). The outlet of the P funnel was held with a finger, and each of the prepared cement milks was poured up to the marked line on the P funnel (1750 ml). Measurement was started as soon as the finger was released using a time watch, and the time until the cement milk was discharged from the P funnel was measured.

[0093] <Production of Cement Molded Body> [Example 2-1] 400 mL of the prepared cement milk 1 was poured into a cylindrical polyethylene bag (diameter approximately 50 mm × length approximately 550 mm × thickness approximately 0.05 mm) up to the marked line. After injecting as much air as possible and sealing the bag, the bag was hung in an incubator set at 22°C. The bag was left hanging in the incubator for 28 days to harden the contents, producing a total of three cement molded bodies. The obtained cement molded bodies were cylindrical, with a diameter of approximately 5 cm and a length of approximately 20 cm.

[0094] Examples 2-2 to 2-9 and Comparative Examples 2-1 to 2-4 Cement molded bodies were produced in the same manner as in Example 2-1, except that the cement milks shown in Tables 3-1 to 3-3 below were used.

[0095] (Density) The density was measured in accordance with JIS A 5430:2008 (apparent density test).

[0096] (Compression Strength Test) The compression strength of the obtained cement molded body was measured in accordance with JIS A 1108:2018 (Method for compressive test of concrete).

[0097]

[0098]

[0099]

[0100] In the cement milk using the calcium carbonate compound of the example, even if the content of the calcium carbonate compound was increased, there was no significant increase in the P funnel flow time compared to Comparative Example 2-1 in which no calcium carbonate compound was blended, and the cement milk had good fluidity. On the other hand, in Comparative Examples 2-2 to 2-4, the fluidity significantly decreased as the content of the calcium carbonate compound was increased.

[0101] Furthermore, in the cement molded bodies of the Examples, the addition of a calcium carbonate compound improved the compressive strength compared to Comparative Example 2-1. On the other hand, in Comparative Examples 2-2 to 2-4, the compressive strength decreased compared to the blank Comparative Example 2-1, even though a calcium carbonate compound was added. Note that the reason for the decrease in compressive strength relative to the blank in Comparative Examples 2-2 to 2-4 is not clear, but it is presumed that this is due to the fact that the calcium carbonate compound is needle-shaped, which increases its surface energy, causing aggregation and reducing the reinforcing effect, and that the needle-shaped shape increases the viscosity of the cement milk, making it difficult for air bubbles to escape, resulting in the cement molded body being obtained with air bubbles remaining.

[0102] From the above, it was found that the cement milk using the calcium carbonate compound of the example exhibits fluidity comparable to that of the blank product, even when the content of calcium carbonate compound is increased, and when made into a cement molded body, it exhibits excellent compressive strength.

Claims

1. A cubic calcium carbonate compound having a phosphorus atom content of 1000 ppm or less and a sulfur atom content of 100 ppm or more.

2. The calcium carbonate compound according to claim 1, having an average particle diameter by the laser diffraction method of 2 μm or more and 25 μm or less.

3. The BET specific surface area is 0.3 m ２ / g or more and 3 m ２ / g or less, and the calcium carbonate compound according to claim 1.

4. The calcium carbonate compound according to claim 1, having an apparent specific gravity of 1 g / mL or more and 2 g / mL or less.

5. The calcium carbonate compound according to claim 1, having a P funnel flow-down time of 7 seconds or more and 10 seconds or less.

6. The calcium carbonate compound according to claim 1, having a magnesium content of 1000 ppm or more.

7. The calcium carbonate compound according to claim 1, wherein the calcium carbonate compound is a synthetic calcium carbonate compound.

8. The calcium carbonate compound according to claim 1, which is for an inorganic molded body.

9. An inorganic molded body comprising the calcium carbonate compound according to any one of claims 1 to 8.

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