Calcium-based carbonate compound and inorganic molded body

Abstract

To provide a calcium-based carbonate compound which enables the fluidity of a mixture thereof to be maintained during the production process, while improving the strength of the molded body; and also to provide an inorganic molded body.SOLUTION: Provided is a cubic calcium-based carbonate compound that 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 is preferably 2 μm to 25 μm inclusive as measured by a laser diffraction method. The BET specific surface area of the calcium-based carbonate compound is preferably 0.3 m2 / g to 3 m2 / g inclusive.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to calcium carbonate compounds and inorganic molded bodies.

Background Art

[0002] An inorganic molded body is a molded body mainly composed of inorganic substances such as hydraulic materials and siliceous materials, and has properties such as fire resistance, light weight, high strength, and workability. Therefore, it is widely used for exterior wall materials, roof base materials, eaves and ceiling materials of houses, etc. It is also widely used for the foundation parts, walls, columns, floors, etc. of buildings where strength and fire resistance are required.

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

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the strength of the inorganic molded body obtained by the above technique may decrease, and the fluidity of the raw material mixture in the manufacturing process may decrease, and as a result, the working efficiency of the entire manufacturing process may decrease.

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

Means for Solving the Problems

[0007] As a result of intensive studies, the present inventors have found that the above problems can be solved by the following configuration, and have completed the present invention.

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

[0009] As a result of the studies by the present inventors, as a factor for acicularization or rod-shapedization (hereinafter also collectively referred to as "acicularization, etc.") that results in a high aspect ratio during the crystal growth of the calcium-based carbonate compound, a phosphorus atom acts as a factor that promotes acicularization, etc., and a sulfur atom acts as a factor that inhibits acicularization, etc. Since the calcium-based carbonate compound has a phosphorus atom and a sulfur atom content within a specific range, the shape can be efficiently controlled to a cubic shape.

[0010] On the other hand, in the field of inorganic molded bodies, it is widely known to increase the strength of inorganic molded bodies by using acicular or fibrous reinforcing materials such as acicular calcium carbonate. However, if the blending amount of the acicular reinforcing material is increased for further strength improvement, the fluidity of the mixture decreases as described above, so that the improvement of strength and the maintenance of fluidity are in a so-called trade-off relationship. As a result of repeated studies by the present inventors, surprisingly, it has been found that a cubic calcium-based carbonate compound can improve the strength of the obtained inorganic molded body 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 not clear, it is speculated as follows. Since 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 substances. As a result, the fluidity of the mixture can be maintained. In addition, the strength of the inorganic molded body can be improved due to the improvement of the strength and density of the calcium carbonate compound itself due to its cubic shape, and the homogeneous dispersion or homogeneous filling due to the isotropy (non-orientation) in the mixture. Furthermore, the viscosity of the mixture containing needle-shaped substances is high, and the bubbles in the mixture are difficult to escape. If the final product is obtained with bubbles remaining, the strength of the final product may decrease. In the case of a cubic calcium carbonate compound, it is speculated that the bubbles in the mixture are more likely to escape due to the fluidity and isotropy as described above, and thus it is also possible to prevent or improve the decrease in strength in this regard.

[0013] In this specification, "cubic shape" does not refer to a regular cubic shape, but to a shape that can be regarded as approximately cubic. For example, even if one or more of the vertices of the cube are rounded or chipped, if the cube can be restored by complementing that part, it is in a cubic shape. Also, if the length of one side of the target shape is within the range of 50% or more and 150% or less of the length of the other side, the target shape is in a cubic shape. Furthermore, the shape of one surface of the target shape is not limited to a square, and as long as the ratio of the lengths of the two sides is satisfied, it can be any of a trapezoid, a rhombus, a quadrilateral with different lengths of the four sides, etc. In addition, it is not necessary for all the particles constituting the calcium carbonate compound to be cubic. When the ratio of cubic particles among all the particles is the largest, the calcium carbonate compound is cubic.

[0014] In this specification, the "calcium-based carbonate compound" is a compound mainly composed of calcium carbonate, and is a concept that allows the inclusion or coexistence of other sub-components that can be incorporated in the manufacturing process or the like. The calcium carbonate content in the calcium-based carbonate compound is preferably 90% by mass or more. As a method for measuring the content ratio of calcium carbonate in the calcium-based carbonate compound, the disodium ethylenediaminetetraacetate titration method can be preferably adopted.

[0015] <Disodium Ethylenediaminetetraacetate Titration Method> Weigh 1 g of the calcium-based carbonate compound (dried at 105 °C for 2 hours) as a sample, suspend it in 50 mL of water, add 10 mL of hydrochloric acid (a solution prepared by mixing concentrated hydrochloric acid and water in a volume ratio of 1:1), and heat and dissolve it. After cooling, transfer it to a 250 mL volumetric flask, add water to make up to the same volume. Take 5.00 mL from this, and add water so that the total volume of the solution is about 50 mL. Add 5 mL of buffer solution (a solution prepared by dissolving 500 g of potassium hydroxide in water to make 1,000 mL), and further add a commercially available dithizone NN dilution powder, and titrate with a titrant (a solution prepared by dissolving about 3.8 g of disodium ethylenediaminetetraacetate in water to make 1,000 mL). End the titration when the color of the solution changes from red to blue. Calculate the calcium carbonate content (%) by the following formula.

[0016]

Equation

[0017] In one embodiment, the average particle size of the calcium-based carbonate compound by the laser diffraction method is preferably 2 μm or more and 25 μm or less. In one embodiment, the BET specific surface area of the calcium-based carbonate compound is 0.3 m 2 / g or more and 3 m 2It is preferably below / g. Also, in one embodiment, the apparent specific gravity of the calcium-based carbonate compound is preferably 1 g / mL or more and 2 g / mL or less. By satisfying these properties alone or in combination, the compatibility between fluidity and strength can be exhibited at a higher level.

[0018] In one embodiment, according to the calcium-based carbonate compound, the P-funnel flow-down time can be 7 seconds or more and 10 seconds or less. Thereby, the calcium-based carbonate compound can 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 raw materials, production methods, etc. For example, when using raw materials relatively rich in magnesium (such as seawater), the magnesium content in the calcium-based carbonate compound will be 1000 ppm or more. When using raw materials relatively low in magnesium (such as the supernatant of concrete sludge), the magnesium content in the calcium-based carbonate compound will be less than 1000 ppm.

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

[0021] In other embodiments of the present invention, It relates to an inorganic molded body containing the calcium-based carbonate compound.

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

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

BEST MODE FOR CARRYING OUT THE INVENTION

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

[0025] <Calcium carbonate compound> The calcium carbonate compound according to the present embodiment is cubic. In the calcium carbonate compound, the content of phosphorus atoms is 1000 ppm or less, and the content of sulfur atoms is 100 ppm or more.

[0026] In the calcium carbonate compound, as long as the content of phosphorus atoms is 1000 ppm or less, it is not particularly limited. The content of phosphorus atoms is preferably 500 ppm or less, more preferably 100 ppm or less. On the other hand, although the content of phosphorus atoms is preferably as small as possible, it may be contained in an amount of about 1 ppm. By setting the content of phosphorus atoms, which is one factor in the acicularization of the calcium carbonate compound, to the predetermined amount, cubic calcium carbonate compounds can be efficiently formed.

[0027] In the calcium carbonate compound, as long as the content of sulfur atoms is 100 ppm or more, it is not particularly limited. It is preferably 500 ppm or more, more preferably 1000 ppm or more. The content of sulfur atoms is preferably 10000 ppm or less, more preferably 5000 ppm or less. By setting the content of sulfur atoms to the predetermined amount, an inhibitory effect such as acicularization can be achieved, and cubic calcium carbonate compounds can be efficiently obtained.

[0028] The average particle diameter of the calcium carbonate compound by laser diffraction method is preferably 2 μm or more and 25 μm or less, more preferably 4 μm or more and 22 μm or less, and even more preferably 6 μm or more and 18 μm or less. Thereby, the fluidity of the mixture containing the calcium carbonate compound can be suitably maintained. In addition, the strength of the obtained inorganic molded body can be further improved.

[0029] The BET specific surface area of the calcium carbonate compound is preferably 0.3 m 2 / g or more and 3 m 2 / g or less, more preferably 0.4 m 2 / g or more and 2.6 m 2 / g or less, and even more preferably 0.5 m 2 / g or more and 2.4 m 2 / g or less. Thereby, the fluidity of the mixture containing the calcium carbonate compound can be suitably maintained, and the dispersibility of the calcium carbonate compound can also be improved. In addition, the strength of the obtained 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. Thereby, the fluidity of the mixture containing the calcium carbonate compound can be suitably maintained. In addition, the density and strength of the calcium carbonate compound are increased, and the strength of the obtained inorganic molded body can be further improved.

[0031] The P-funnel flow-down time of the calcium carbonate compound is preferably 7 seconds or more and 10 seconds or less, more preferably 7.5 seconds or more and 9.8 seconds or less, and even more preferably 8 seconds or more and 9.5 seconds or less. Since the calcium carbonate compound is cubic, excellent fluidity can be exhibited.

[0032] The content of magnesium in the calcium-based carbonate compound may be 1000 ppm or more, may be 5000 ppm or more, or may be 10000 ppm or more. The upper limit of the content of magnesium is about 50000 ppm depending on raw materials, manufacturing methods, etc.

[0033] As the crystal structure of the calcium-based carbonate compound, a calcite type, an aragonite type, or a combination thereof can be preferably adopted. From the viewpoint of obtaining a cubic calcium-based carbonate compound, it is preferable that the calcite type crystal structure is relatively more and the aragonite type crystal structure is relatively less.

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

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

[0036] (Manufacturing method of calcium-based carbonate compound) The manufacturing method of the calcium-based carbonate compound is not particularly limited, and a known manufacturing method can be adopted. Typically, a solution method for manufacturing a calcium-based carbonate compound by performing salt exchange by bringing a carbonate (carbonate ion) into contact with calcium (calcium ion) such as seawater can be preferably adopted. Ca 2+ +CO3 2- →CaCO3(A)

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

[0038] The contact between the carbonate and seawater or the like may be carried out by introducing an aqueous solution or slurry of the carbonate into the seawater or the like, or by introducing the seawater or the like into the aqueous solution or slurry. From the viewpoint of efficiently obtaining the target cubic calcium-based carbonate compound, it is preferable to introduce it all at once.

[0039] Seawater may be used as it is pumped from the nearby sea, or may be used after performing treatments such as filtration. The pumping is not limited to the offshore area, and may be carried out at any place as long as seawater can be obtained. Calcium-rich seawater generated when magnesium hydroxide is removed from seawater may also be used.

[0040] The input amount of the carbonate is not particularly limited as long as it is set so that the amount of carbonate ion required for the reaction with the amount of calcium ion in seawater or the like can be obtained according to the above reaction formula (A). Although an equimolar amount of the calcium ion amount and the carbonate ion amount is preferable, the carbonate ion amount may be in the range of 50 to 200% in terms of molar ratio with respect to the calcium ion amount.

[0041] The salt exchange reaction by the contact between the carbonate and seawater or the like proceeds relatively rapidly. The reaction time may be set to such an extent that the salt exchange reaction proceeds sufficiently, and can be set to 1 second or more, preferably 1 minute or more and 60 minutes or less, and more preferably 5 minutes or more and 50 minutes or less.

[0042] The generated calcium-based carbonate compound may be filtered and dried to be in powder form, or may be used as a calcium-based carbonate compound source in slurry form or cake form without going through filtration and drying.

[0043] <Uses of Calcium-based Carbonate Compounds> The use of the calcium-based carbonate compound is not particularly limited. As uses, for example, it is suitable as a high-functional material for inorganic molded articles typified by building materials and buildings, a filler for resins, and the like. Hereinafter, the mode of using the calcium-based carbonate compound for inorganic molded articles will be described.

[0044] <Inorganic molded article> The inorganic molded article is not particularly limited, and typically includes a molded plate for building materials, a concrete building (concrete molded article), and the like. Hereinafter, applicable compositions and the like will be described in detail according to the use.

[0045] (Molded plate for building materials) The molded plate preferably contains a hydraulic material, a siliceous material, a reinforcing fiber material, and a calcium-based carbonate compound.

[0046] (Hydraulic material) Examples of the hydraulic material include cementitious materials, gypsum, lime, slag, etc. Examples of the cementitious materials include commonly used cements such as ordinary Portland cement, early-strength cement, medium-heat cement, fly ash cement, blast furnace slag cement, and alumina cement. Examples of the gypsum include anhydrous gypsum, hemihydrate gypsum, dihydrate gypsum, etc. Examples of the slag include blast furnace slag, converter slag, etc. 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 the materials constituting the molded plate. By setting the content of the hydraulic material within the above range, the physical properties such as the flexural strength and peel strength of the molded plate can be improved, and the high bulk density of the molded plate can be suppressed to enhance the workability during construction.

[0048] (Siliceous material) Examples of siliceous materials include materials rich in SiO2 such as 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.). These siliceous materials can be used alone or in combination of two or more. Talc, mica, and wollastonite can also be used as the reinforcing fiber materials 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 the materials constituting the formed plate. If the content of the siliceous material is within the above range, it becomes possible to set the flexural strength, bulk density, water absorption rate, dimensional stability, etc. of the formed plate within the target range. In addition, as the siliceous material, lightweight aggregates such as perlite, fly ash balloons, and shirasu balloons with a unit volume mass of 0.5 g / cm 3 When blending the following lightweight aggregates, in order to prevent the bulk density from becoming too low and the strength such as flexural strength and peel strength from becoming weak, it is preferable to use other siliceous materials in combination so that the content of the lightweight aggregate is 20% by mass or less based on the total amount of the materials constituting the formed plate.

[0050] (Reinforcing fiber material) Examples of the reinforcing fiber material include pulp materials 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] For improving the strength and imparting toughness to the formed plate, the content of the reinforcing fiber material is preferably 2% by mass or more and 30% by mass or less, more preferably 3% by mass or more and 26% by mass or less, and even more preferably 4% by mass or more and 22% by mass or less, based on the total amount of the materials constituting the formed plate. By setting the content of the reinforcing fiber material within the above range, while exerting a sufficient reinforcing effect, it is possible to suppress the fibers from protruding on the surface of the formed plate and improve the smoothness. When an inorganic reinforcing fiber material with an average length of 1 mm to 50 mm is blended as the reinforcing fiber material, in order to improve the smoothness of the formed plate, 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 the materials constituting the formed plate.

[0052] (Calcium-based carbonate compound) As the calcium-based carbonate compound, the above-mentioned calcium-based carbonate compound can be preferably adopted.

[0053] The content of the calcium-based 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 the materials constituting the formed plate. By blending a calcium-based carbonate compound with low thermal conductivity in the content within the above range, the strength and fire resistance of the formed plate can be improved.

[0054] (Optional component) In addition to the above materials, various materials such as resin hollow bodies, wood chips, wood powder, resin powder, defoaming agents, flocculants, water repellents, thickeners (such as methyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, etc.), and dispersants can be variously blended according to the purpose in order to impart various functions to the formed plate. It is also possible to appropriately add and use recycled materials obtained by pulverizing end materials and the like generated during the processing of the formed plate.

[0055] The bulk density of the formed plate is preferably 0.7 g / cm 3 or more and 2.0 g / cm 3 or less, and preferably 0.8 g / cm 3 or more and 1.8 g / cm3 It is more preferable that it is 0.9 g / cm 3 or more and 1.6 g / cm 3 or less.

[0056] (Method for manufacturing a formed plate) The method for manufacturing the formed plate according to this embodiment is not particularly limited, and generally used papermaking methods, extrusion molding methods, flow-on molding methods, casting molding methods, press (compression) molding, etc. can be used. The formed plate can be obtained by subjecting the green sheet formed by these methods to press dehydration or pattern processing such as embossing, and then curing by normal temperature curing, steam curing, autoclave curing, etc. Furthermore, drying may be performed, and shape processing and painting may be performed as necessary.

[0057] (Uses of the formed plate) The uses of the formed plate are not particularly limited, and it can be suitably used as interior and exterior finishing materials such as building wall materials, floor materials, roof materials, various boards, exterior decoration members, and fittings, and performance maintenance materials such as sealants, heat insulating materials, sound absorbing materials, and waterproof materials. The formed plate is preferably a cement-based formed plate containing a cementitious material, and more preferably a calcium silicate formed body.

[0058] (Concrete building) The concrete building is composed of a cured body of a hydraulic composition. The hydraulic composition is composed of a powder containing at least one of blast furnace slag, an expansion material, slaked lime, quicklime, fly ash, and Portland cement in addition to a calcium-based carbonate compound. As the calcium-based carbonate compound, the above-mentioned calcium-based carbonate compound can be preferably adopted.

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

[0060] The hardened body of the hydraulic composition is obtained by hardening the paste obtained by kneading water into the above hydraulic composition. Further, the hardened body of the hydraulic composition mixed material is obtained by hardening the kneaded material (corresponding to fresh mortar or fresh concrete) obtained by kneading water into the above hydraulic composition mixed material, and corresponds to mortar or concrete.

[0061] The proportion of the calcium-based carbonate compound in the above powder (the proportion of the calcium-based carbonate compound to cement) is in the range of 1% to 60% by mass, preferably 3% to 50% by mass, and more preferably 5% to 40% by mass.

[0062] For blast furnace slag, it is desirable to use blast furnace slag fine powder used in JIS (Japanese Industrial Standards) R5211 "Blast Furnace Cement" or blast furnace slag fine powder conforming to JIS A6206 "Blast Furnace Slag for Concrete". Further, the blast furnace slag has a specific surface area of 2000 to 10000 cm 2 / g, preferably 3500 to 7000 cm 2 / g, is desirably used.

[0063] As the expansion agent, for example, an expansion agent defined in JIS A6202 "Expansion Agent for Concrete" may be used. It is desirable to add the expansion agent at a ratio of 2 to 9% by mass based on the entire hydraulic composition.

[0064] For slaked lime, for example, those defined in JIS R9001 "Lime for Industrial Use" may be used. Further, since quicklime becomes slaked lime when it comes into contact with water, for example, quicklime defined in JIS R9001 "Lime for Industrial Use" can be used instead of slaked lime. In this case, it is advisable to correct the amount of water required when quicklime changes to slaked lime. For fly ash, for example, those conforming to JIS A6201 "Fly Ash for Concrete" may be used.

[0065] For Portland cement, ordinary Portland cement is used. In addition to this, other types of Portland cement such as early strength Portland cement, ultra-early strength Portland cement, moderate heat Portland cement, low heat Portland cement, sulfate resistant Portland cement, etc. as defined in JIS R5210 "Portland Cement", and JIS R5214 "Eco Cement" can also be used.

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

[0067] Also, when using Portland cement and blast furnace slag or fly ash, those that are premixed, such as JIS R5211 "Blast Furnace Cement", or, for example, JIS R5213 "Fly Ash Cement", may be used alone or in combination.

[0068] Since the calcium-based carbonate compound having the above characteristics is used, the hydraulic composition and the hydraulic composition mixing material exhibit good fluidity, and the concrete hardened body can exhibit excellent compressive strength.

[0069] The density of the concrete structure is preferably 0.7 g / cm 3 or more and 2.0 g / cm 3 or less, more preferably 0.8 g / cm 3 or more and 1.8 g / cm 3 or less, and even more preferably 0.9 g / cm 3 or more and 1.6 g / cm 3 or less.

Examples

[0070] Hereinafter, the present invention will be described in detail using examples. However, the present invention is not limited to the following examples as long as the gist thereof is not exceeded. The measurement and evaluation of physical properties and the like were carried out as follows.

[0071] <Evaluation of Calcium Carbonate Compounds> For the calcium carbonate compounds and the like obtained in each production example, the following analyses were performed. The results of each analysis are shown in Table 1 and Figures 1 and 2.

[0072] (1) BET specific surface area The sample powder pretreated at about 130 °C for about 30 minutes in a nitrogen gas atmosphere using an 8 - stage pre - heating unit (manufactured by MOUNTECH) was measured for BET specific surface area (m 2 / g) by the nitrogen gas adsorption method using a Macsorb HM Model - 1208 (manufactured by MOUNTECH) as a BET specific surface area measuring device.

[0073] (2) Average particle diameter by laser diffraction method 50 mL of ethanol was taken in a 100 - mL beaker, and about 0.2 g of the sample powder was put into the aforementioned 100 - mL beaker, and ultrasonic treatment (UD - 201 manufactured by Tomy Seiko Co., Ltd.) was performed for 3 minutes to prepare a dispersion. This dispersion was measured using a laser diffraction method - particle size distribution meter (Microtrac HRA Model 9320 - X100 manufactured by Nikkiso Co., Ltd.) with the D 50 value 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 atom, sulfur atom and magnesium atom <ICP - AES method> Weighed 0.2 g of calcium carbonate compound as a sample, moistened it with water, added 10 mL of hydrochloric acid (a solution prepared by mixing concentrated hydrochloric acid and water at a volume ratio of 1:1) using a pipette, and heated and dissolved it. After cooling, it was transferred to a 250 mL volumetric flask, and water was added up to 250 mL to make it up to the mark. 20 mL was taken from this and transferred to a 50 mL volumetric flask, and water was added up to 50 mL to prepare a test liquid for measurement. On the other hand, 20 mL was taken from the 250 mL made-up aqueous solution described above and transferred to a 50 mL volumetric flask, and standard solutions of each element (phosphorus atom, sulfur atom, and magnesium atom) were arbitrarily added additionally to prepare calibration standard solutions with different concentrations. Note that as the standard solutions of each element, 1000 ppm standard solutions for atomic absorption (commercially available) were used.

[0076] The calibration standard solutions with different concentrations to which each element was added additionally and the test liquid for measurement were set in the autosampler of an inductively coupled plasma optical emission spectrometry (ICP - AES) apparatus (manufactured by Hitachi High - Technologies Corporation, "SPECTROBLUE FMS36 type"), and the amount (ppm) of magnesium atoms 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 property: Aqueous solution Integration times: 3 times Sample order: For each sample Measurement method: Standard addition method Calibration curve weighting: None Measurement wavelength: Phosphorus atom 177.495 nm, sulfur atom 182.034 nm, magnesium atom 279.553 nm

[0077] (5) Calculation of the ratio of the peak intensity I of 46° (aragonite) to the peak intensity I of 29° (calcite) by XRD measurement a of c for After fixing the sample powder to a specified sample stage with a spatula blade by pressing and compacting, measurements were carried out using an XRD apparatus (MiniFlex600-C manufactured by Rigaku Corporation), and identification analysis as a crystalline substance was performed. At the 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 ratio (I a ) of the peak intensity I c at 29° (calcite) to the peak intensity I a / I c ) was determined.

[0078] (6) Scanning electron microscope observation Double-sided tape was attached to an aluminum sample stage, and the sample powder was applied onto it from above like tracing with a spatula blade. After platinum evaporation, a photograph of the particle image of the sample powder was taken at 2000 times magnification using a scanning electron microscope (FE-SEM: S-4700 manufactured by Hitachi, Ltd.). SEM photographs of the examples and comparative examples are shown in Figs. 1 to 2.

[0079] (Production of calcium-based carbonate compound) [Example 1-1] Calcium-based carbonate compound (cubic shape) 8510 g of sodium carbonate reagent (manufactured by Wako Pure Chemical Industries, Ltd., purity 99.8%) was put into a 220 L capacity SUS container with a baffle plate filled with 100 L of water in advance under stirring to prepare sodium carbonate. On the other hand, 1000 L of seawater (Ca 2+ content: 0.25 g / dL) after removing magnesium hydroxide from the seawater discharged within the premises of Kojima Chemical Industry Co., Ltd. was put into a 2000 L capacity polyethylene container, and 100 L of the above-mentioned sodium carbonate aqueous solution was added all at once under stirring at 25°C, and then the reaction was carried out by continuing stirring for about 30 minutes. Then, it was filtered, washed with about 5 times the amount of water with respect to the solid content, dried at 110°C for 24 hours, pulverized, and a sample powder of the calcium-based carbonate compound was obtained.

[0080] [Example 1-2] Calcium-based carbonate compound (cubic shape) After removing magnesium hydroxide from 1000 L of seawater, 12.7 kg of magnesium chloride hexahydrate was added under stirring, and then 100 L of the above-mentioned aqueous sodium carbonate solution was added all at once. Except for this, the same operations as in Example 1-1 were performed to obtain a sample powder of a calcium-based carbonate compound.

[0081] [Example 1-3] Calcium-based carbonate compound (cubic shape) To 100 L of seawater from which magnesium hydroxide had been removed, 10 L of the above-mentioned aqueous sodium carbonate solution was added all at once under stirring, and then stirring was continued for about 30 minutes. Using the reaction solution after this as a seed, another 100 L of seawater from which magnesium hydroxide had been removed was added, 10 L of the above-mentioned aqueous sodium carbonate solution was added all at once under stirring, and then stirring was continued for about 30 minutes. This series of operations was continued for a total of 10 times. Except for those operations, the same operations as in Example 1-1 were performed to obtain a sample powder of a calcium-based carbonate compound.

[0082] [Comparative Example 1-1] Calcium-based carbonate compound (needle shape) 69 80 g of commercially available slaked lime powder (manufactured by Yoshimi Lime Industry Co., Ltd., industrial grade best-quality slaked lime), 630 g of aragonite seed crystal powder, and 3000 g of disodium hydrogen phosphate dodecahydrate were prepared, and each was put into a 220 L capacity SUS container with baffles filled with 180 L of water in advance under stirring to prepare a mixed slurry of raw materials. Then, the temperature was raised to 70 °C, and under that temperature, a stirrer equipped with a single-stage turbine blade was used to stir at a rotational speed of 150 rpm. An exhaust gas extraction pipe was connected to the exhaust outlet of a steam boiler for water vapor production using LNG as fuel, and while drawing in the exhaust gas using a test blower, when measured with a CO2 concentration measuring instrument (XP-3140 manufactured by Shinko Cosmos Electric Co., Ltd.), the CO2 concentration showed 10% by volume. The exhaust gas was introduced into the above-mentioned 220 L capacity SUS container at a rate of 100 L / min using a test blower and reacted for 7 hours. Then, it was filtered, washed with about 5 times the amount of water relative to the solid content, dried at 110 °C for 24 hours, pulverized, and a sample powder of a calcium-based carbonate compound was obtained.

[0083]

Table 1

[0084] <Evaluation> Using the obtained calcium carbonate compound, the measurement of the P funnel flow-down time, as well as the production of a cement compact and the compressive strength test were carried out. The results are shown in Table 3.

[0085] (Preparation of Cement Milk 1) 2 kg of cement (manufactured by Tokuyama Corporation, "Ordinary Portland Cement (N)") was put into 1600 mL of water in about 20 seconds, and mixed with a stirrer (manufactured by Yamato Scientific Co., Ltd., "Lab Stirrer (LR500B)") for 3 minutes from the start of input. After stopping the stirring and allowing to stand for 3 minutes, it was stirred 10 times manually with a stirring rod (manufactured by AS ONE Corporation, "Stirring Rod (POM) φ10×300 mm") 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 shown in the following Table 2-1 in the types and amounts were put into 1600 mL of water, stirred manually with the above stirring rod for about 30 seconds, and then stirred at 400 rpm using the stirrer to obtain a mixture. 2 kg of cement (manufactured by Tokuyama Corporation, "Ordinary Portland Cement (N)") was put into this mixture in about 20 seconds, and mixed with the stirrer for 3 minutes from the start of input. After stopping the stirring and allowing to stand for 3 minutes, it was stirred 10 times manually with the above stirring rod to prepare Cement Milks 2 to 7.

[0087]

Table 2-1

[0088] (Preparation of Cement Milks 8 to 10) Except for using the calcium carbonate compounds of Example 1-2 shown in the following Table 2-2 in the types and amounts, the same operations as those for the preparation of Cement Milks 2 to 7 were carried out to prepare Cement Milks 8 to 10.

[0089] [Table 2-2]

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

[0091] [Table 2-3]

[0092] (P Funnel Flow Time Test Method) In accordance with the "Test Method for Fluidity of Injection Mortar for Prepacked Concrete (Method by P Funnel)" (JSCE-F521-1999), the P funnel flow time was measured. With the outlet of the P funnel held with a finger, each of the prepared cement milks was poured up to the marked line of the P funnel (1750 ml), and the measurement was started simultaneously with releasing the finger with a stopwatch. The time until the cement milk was discharged from the P funnel was measured.

[0093] (Manufacture of Cement Moldings) [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 air as much as possible and sealing it, it was suspended in a thermostat set at 22°C. It was left for 28 days while suspended in the thermostat to cure the contents, thereby manufacturing a total of 3 cement moldings. The obtained cement moldings 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 moldings were manufactured 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] (Compressive Strength Test) The compressive strength of the obtained cement compact was measured in accordance with JIS A 1108:2018 (Method of Compression Test for Concrete).

[0097]

Table 3-1

[0098]

Table 3-2

[0099]

Table 3-3

[0100] In the cement milk using the calcium-based carbonate compound of the example, even when the content of the calcium-based carbonate compound was increased, there was no significant increase in the P funnel flow time compared to Comparative Example 2-1 without the calcium-based carbonate compound, and it had good fluidity. On the other hand, in Comparative Examples 2-2 to 2-4, the fluidity decreased significantly as the content of the calcium-based carbonate compound was increased.

[0101] Furthermore, in the cement molded body of the example, by blending a calcium-based carbonate compound, the compressive strength was improved compared to Comparative Example 2-1. On the other hand, in Comparative Examples 2-2 to 2-4, even when a calcium-based carbonate compound was blended, the compressive strength decreased compared to the blank Comparative Example 2-1. Although the reason for the decrease in the compressive strength in terms of the blank ratio in Comparative Examples 2-2 to 2-4 is not clear, it is presumed that the calcium-based carbonate compound is needle-shaped and the surface energy has increased, resulting in aggregation and a decrease in the reinforcing effect, or that being needle-shaped increases the viscosity of the cement milk, making it difficult for air bubbles to escape and the cement molded body being obtained with air bubbles remaining.

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

Claims

1. The content of phosphorus atoms is 1000 ppm or less, the content of sulfur atoms is 100 ppm or more, the crystal structure is calcite type, aragonite type or a combination thereof, and the apparent specific gravity is 1 g / mL or more and 2 g / mL or less for a cubic calcium-based carbonate compound.

2. The calcium-based carbonate compound according to Claim 1, wherein the average particle diameter by the laser diffraction method is 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, the calcium-based carbonate compound according to claim 1.

4. The calcium-based carbonate compound according to Claim 1, wherein the P funnel flow-down time is 7 seconds or more and 10 seconds or less.

5. The calcium-based carbonate compound according to Claim 1, wherein the content of magnesium is 1000 ppm or more.

6. The calcium-based carbonate compound according to Claim 1, wherein the calcium-based carbonate compound is a synthetic calcium-based carbonate compound.

7. The calcium-based carbonate compound according to Claim 1, which is for an inorganic molded body.

8. An inorganic molded body containing the calcium-based carbonate compound according to any one of Claims 1 to 7.

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