Method for producing calcium carbonate compounds, CaO-containing composition, calcium carbonate compounds, and inorganic molded articles

Abstract

Method for producing calcium-based carbonate compounds using a CaO-containing composition suitable for carbonation reactions. The present invention provides a method, a CaO-containing composition, a calcium-based carbonate compound, and an inorganic molded article. [Solution] Prepare a CaO-containing composition having a free CaO content of 50% by mass or more. Preparation process, and contact of the CaO-containing composition with carbon dioxide to form a calcium-based carbonate compound A method for producing a calcium-based carbonate compound, comprising a carbonation step to form a carbonate.

Description

[Technical Field]

[0001] The present invention provides a method for producing calcium carbonate compounds, a CaO-containing composition, and calcium carbonate compounds. This relates to compounds and inorganic molded articles. [Background technology]

[0002] In recent years, with the growing environmental awareness, waste, exhaust gases, and waste heat generated in industrial processes have become increasingly important. Attempts are also being made to reuse the by-products and by-generated energy. Calcium carbonate is produced by carbonizing these calcium-containing waste products with carbon dioxide. A technology has been proposed (Japanese Patent Publication No. 2006-69860). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2006-69860 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] However, since waste contains various components, the carbonation reaction must be efficient. It's not easy to make it progress.

[0005] This invention relates to the production of calcium-based carbonate compounds using a CaO-containing composition suitable for carbonation reactions. To provide a manufacturing method, a CaO-containing composition, a calcium-based carbonate compound, and an inorganic molded article. The objective. [Means for solving the problem]

[0006] After diligent research, the inventors have concluded that the above problem can be solved by the following configuration. The inventors have completed the present invention.

[0007] In one embodiment, the present invention prepares a CaO-containing composition having a free CaO content of 50% by mass or more, and and carbonates the CaO-containing composition with carbon dioxide to form a calcium-based carbonate compound carbonation step relates to a method for producing a calcium-based carbonate compound including the above steps.

[0008] As a result of investigations by the inventors, by using a CaO-containing composition having an increased content of free CaO that contributes to the carbonation reaction as the CaO-containing composition to be carbonated, it has been found that the carbonation reaction can proceed efficiently. In this method for producing the calcium-based carbonate compound, since a CaO-containing composition having a free CaO content of 50% by mass or more is used as the CaO-containing composition to be carbonated, the carbonation reaction can proceed efficiently without adding seed crystals or performing other operations during the carbonation step. composition, the carbonation reaction can proceed efficiently without adding seed crystals or performing other operations during the carbonation step. the carbonation reaction can proceed efficiently.

[0009] In one embodiment, it is preferable that the preparation step includes a sieving step of sieving a CaO-containing raw material and collecting the fraction passing through the sieve. By subjecting a CaO-containing raw material typified by waste from various industrial processes to the sieving step, fractions having a relatively large size and a low free CaO content can be removed, and the content of free CaO in the CaO-containing composition can be improved. This makes it possible to improve the content of free CaO in the CaO-containing composition.

[0010] In one embodiment, it is preferable that the sieving step is performed wet. This promotes the elution and pulverization of free CaO particles (or free (CaO) ·(H2O) m ·(H2O) n particles). This allows for a further improvement in the free CaO content of the CaO-containing composition. ru.

[0011] In one embodiment, the preparation step includes a grinding step of grinding the CaO-containing raw material. This is preferable. Free CaO particles (or free (CaO) m (H2O) n (Particles) are crushed By miniaturizing the carbon dioxide, the reaction activity with carbon dioxide is improved, and the carbon dioxide becomes more advantageous. It is possible to achieve basic fixation.

[0012] In one embodiment, the CaO-containing raw material is obtained through a process involving the calcination and quenching of limestone. It may be derived from these wastes. Among various types of waste, waste derived from the process in question. Since it has a relatively high free CaO content, it is possible to easily and efficiently create a CaO-containing composition It can give.

[0013] In one embodiment, the average particle size of the CaO-containing composition obtained by laser diffraction is 1 It is preferable that the particle size is between μm and 30 μm. In one embodiment, the CaO-containing composition The BET specific surface area of ​​the object is 10m 2 / g or more 50m 2 It is preferable that the amount is less than / g. By using a CaO-containing composition that is modified or highly activated, free Ca The oxygen content can be further improved.

[0014] In one embodiment, from the viewpoint of efficiency of the carbonation process, the carbon dioxide in the carbonation process The concentration of the element is preferably 1% by volume or more and 50% by volume or less.

[0015] In one embodiment, the carbon dioxide in the carbonation process is emitted from the combustion engine. It is preferably carbon dioxide. This is because it is secondarily generated in industrial processes. Carbon dioxide can be reused, contributing to a reduction in carbon dioxide emissions across the entire industrial process. It is possible.

[0016] In one embodiment, from the viewpoint of efficiency of the carbonation process, the temperature in the carbonation process is, It is preferable that the temperature is between 5°C and 95°C.

[0017] In another embodiment, the present invention is CaO for the production of calcium carbonate compounds, with a free CaO content of 50% by mass or more. Regarding the contained composition.

[0018] The CaO-containing composition, which has a high free CaO content, allows the carbonation reaction to proceed in high yield. Because it can do this, it is suitable for the production of calcium-based carbonate compounds.

[0019] In one embodiment, the CaO-containing composition has a high content of free CaO and carbon dioxide. From the viewpoint of high activation in the reaction with the element, it is preferable that the CaO-containing raw material be sieved or pulverized. It's nice.

[0020] In one embodiment, the CaO-containing raw material is, in terms of the content of free CaO, of limestone It may be derived from waste materials from processes involving incineration and quenching.

[0021] In another embodiment, the present invention is further described as follows: This invention relates to a calcium-based carbonate compound, which is a carbon oxide in the aforementioned CaO-containing composition.

[0022] As a versatile calcium-based carbonate compound, use a carbon oxide from a CaO-containing composition. This can contribute to reducing and effectively utilizing waste, as well as lowering carbon dioxide emissions.

[0023] In one embodiment, the calcium-based carbonate compound is suitable for use in inorganic molded articles. ru.

[0024] In one embodiment, the present invention is This invention relates to an inorganic molded article containing the aforementioned calcium-based carbonate compound.

[0025] Inorganic molded products are mostly composed of inorganic materials such as hydraulic materials and silicate materials. It is a solid material and possesses properties such as fire resistance, light weight, high strength, and workability, making it suitable for exterior wall materials of houses, etc. It is widely used as roofing underlayment, soffit material, etc., and also in buildings where strength and fire resistance are required. It is widely used in the foundation, walls, columns, floors, etc. Thus, inorganic molded materials have a broad range of applications. By using specific calcium-based carbonate compounds, the environmental impact of the entire industrial process can be reduced. It can be measured.

[0026] In this specification, standard abbreviations for elements from the periodic table may be used. Therefore, Elements can be represented by these abbreviations. For example, Ca means calcium; O means acid. It means element; H means hydrogen; Si means silicon; Fe means iron; Al means aluminum It means magnesium; S means sulfur; and Mg means magnesium. The same applies to the following.

[0027] In this specification, "free CaO" means unreacted CaO that has not combined with other substances. This refers to calcium oxide. In addition to the free CaO content, the methods for measuring composition, physical properties, etc., are particularly important. Unless otherwise specified, the examples provided are as described.

[0028] In this specification, "calcium-based carbonate compound" means a compound whose main component is calcium carbonate. A compound that allows for the inclusion or coexistence of other by-components that may be incorporated during the manufacturing process, etc. This is the concept. The calcium carbonate content in calcium-based carbonate compounds is 80% by mass or more. It is preferable that there be a method for measuring the calcium carbonate content in calcium carbonate compounds. The ethylenediaminetetraacetate disodium titration method can be suitably employed.

[0029] <Ethylenediaminetetraacetate disodium titration method> Weigh out 1 g of calcium carbonate compound (dried at 105°C for 2 hours) as a sample, and add water. Suspend in 50 mL and add 10 mL of hydrochloric acid (a solution of concentrated hydrochloric acid and water mixed in a 1:1 volume ratio). Heat and dissolve. After cooling, transfer to a 250 mL volumetric flask and add water to the same volume. Dilute to the nearest whole. Take 5.00 mL from this and add water until the total volume of the liquid is approximately 50 mL. Add this to the solution. Then add a buffer solution (dissolve 500g of potassium hydroxide in water to make 1,000mL). Add 5 mL of the solution, then add the commercially available Dotite NN diluted powder, and then titrate with the titration reagent (Ethylene (A solution made by dissolving approximately 3.8g of disodium diaminetetraacetate in water to make 1,000mL) Titrate with [the specified solution]. Stop the titration when the color of the solution changes from red to blue. According to the following formula, carbonic acid Calculate the calcium content (percentage by mass).

[0030]

number

[0031] [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 1-1 of the present invention. [Figure 3] These are SEM images of calcium-based carbonate compounds according to Examples 1-2 of the present invention. [Figure 4] These are SEM images of calcium-based carbonate compounds from Examples 1-3 of the present invention. [Figure 5] This is an SEM image of a calcium-based carbonate compound of Comparative Example 1-1 of the present invention. [Figure 6] This is a schematic partial perspective view of a heating tester. [Modes for carrying out the invention]

[0032] Method for producing a calcium carbonate compound according to one embodiment of the present invention, CaO-containing composition, The following describes the calcium carbonate compounds and inorganic molded articles. The present invention relates to these practical applications. It is not limited to the form of application.

[0033] <Method for producing calcium carbonate compounds> The method for producing the calcium-based carbonate compound includes a preparation step and a carbonation step. This includes at least one step selected from the group consisting of a sieving step and a grinding step. Preferred. The choice of which preparation step to perform depends on the CaO-containing material being processed. The amount of free CaO in the raw materials and the target CaO-containing composition, including its content and particle size, is determined by considering these factors. It is sufficient to determine this. Below, the following describes an embodiment that includes a sieving step and a grinding step, which are preferred steps as preparation steps. I will explain about that.

[0034] (sieving process) In the sieving process, CaO-containing raw materials are sieved, and the portion that passes through the sieve is recovered. The resulting CaO waste is then collected. Although it is possible to use the raw material containing the substance itself, the CaO-containing raw material is subjected to a sieving process. This makes it possible to prepare a CaO-containing composition with a high free CaO content.

[0035] As long as CaO-containing raw materials contain CaO, various waste generated in industrial processes Waste materials can be used. Specific examples of CaO-containing raw materials include, for example, calcined limestone and Waste from processes that involve sanitation, and paper sludge incineration ash discharged from paper mills, Concrete sludge discharged from concrete product factories, demolition of concrete structures Concrete waste generated as a result, and the burning of coal in coal-fired power plants and waste incineration plants Coal ash produced by this process, steel slag generated in the steel manufacturing process, acetylene gas production process Examples include carbide slag discharged from the area. In terms of the free CaO content, CaO-containing The raw materials are waste products from the process of calcining and smoldering limestone (hereinafter also referred to as "lime slag"). It is preferable that it originates from ( ). Lime slag mainly consists of sieves produced during the sieving process after calcination of limestone. The lower fraction (hereinafter also referred to as "quicklime-based lime slag") and the sieving process after quenching in the next step. This includes sieved fractions (hereinafter also referred to as "slaked lime slag"), etc.

[0036] The free CaO content in CaO-containing raw materials is generally low, and waste is generated. It changes depending on the process. The free CaO content in CaO-containing raw materials is particularly limited. Although not included, it is between 10% and 90% by mass.

[0037] The mesh size of the sieve is determined by the size of the CaO-containing raw material being processed and the target CaO-containing composition. The size can be adjusted as needed. The sieve opening is according to JIS Z 8801-1 A nominal mesh opening conforming to the standard can be suitably adopted. Typical sieve mesh openings include 8 mm and 6 mm. Examples include 7mm, 5.6mm, 4mm, 2mm, 1mm, etc., but are not limited to these. The sieving can be done in one stage, or in multiple stages, from sieves with large mesh openings to sieves with small mesh openings. That's fine,

[0038] The sieving process may be carried out either dry or wet, but fine particles adhering to the sieved fraction Free CaO particles (or free (CaO) m (H2O) n In terms of easily eluting particles It is preferable to carry out the sieving process in a wet manner. When the sieving process is carried out in a wet manner, water is usually used as the dispersion medium. It is used. When dispersing CaO-containing raw materials in water, the concentration should be determined considering dispersion efficiency, sieving efficiency, etc. This can be set as appropriate. The amount of CaO-containing raw material per liter of water must be 10g or more. Preferably 300g or less, more preferably 15g to 250g, and 20g to 200g. The following are even more preferable.

[0039] After adding the CaO-containing raw material to the water, stir to allow the CaO-containing raw material to dissolve thoroughly in the water. This is preferable. The stirring time is preferably 1 minute to 3 hours, and preferably 5 minutes to 2 hours. This is preferable.

[0040] When the sieving process is performed wet, the material that passes through the sieve is often in the state of a dilute suspension, so the next process When concentrating the solution, it is preferable to allow it to stand until the particles settle. The standing time is not particularly limited. Not specified, preferably 10 minutes to 3 hours, preferably 20 minutes to 2.5 hours, 3 A duration of 0 minutes to 2 hours is preferable.

[0041] Depending on the processing in the next step, a predetermined amount of supernatant liquid is removed after the aforementioned standing stage (concentrating the dispersion). It may be carried out, and further dehydration and drying may be performed.

[0042] When the content rate of free CaO in the particles after the screening process is 50% by mass or more, the particles can be treated as a CaO-containing composition. When the content rate of free CaO in the particles after the screening process is less than 50% by mass, it is preferable to subject the particles to the grinding process as a CaO-containing raw material. When the CaO-containing raw material is slaked lime-based lime sludge, a CaO-containing composition may be obtained only by the screening process.

[0043] (Grinding Process) In the grinding process, the CaO-containing raw material is ground. By the grinding process, free CaO particles (or free (CaO) (H2O) m (H2O) n particles) are refined, and a CaO-containing composition with high reactivity with carbon dioxide can be prepared. The CaO-containing raw material may be either the screened product that has passed through the screening process or the unscreened product that has not passed through the screening process. The screening process is not particularly limited, and a method using a known grinder can be adopted. Examples of grinders include, for example, roller mills; jet mills; high-speed rotary grinders such as hammer mills and pin mills; container-driven mills such as rotary mills, vibration mills, and planetary mills; and media agitation mills such as attritors, bead mills, ball mills, and rod mills.

[0044] The grinding time can be appropriately set in consideration of the content rate and particle size of free CaO in the target CaO-containing composition. The grinding time is preferably 5 minutes or more and 10 hours or less, more preferably 10 minutes or more and 8 hours or less, and even more preferably 30 minutes or more and 6 hours or less.

[0045] When using rotary mills such as ball mills and pot mills, the rotational speed should be 40 rpm or less. Preferably, the speed is 300 rpm or less, more preferably 50 rpm to 200 rpm, and 60 A range of rpm or more and 150 rpm or less is even more preferable.

[0046] The grinding process may be carried out either dry or wet. Dispersion medium when the grinding process is carried out wet. Typically, water is used for this purpose. The concentration when dispersing CaO-containing raw materials in water is determined by the grinding effect. The ratio can be set appropriately, taking into consideration the proportions, etc. The amount of CaO-containing raw material to be added per liter of water is: Preferably 50g to 600g, more preferably 80g to 500g, and 120g. A weight of 400g or less is even more preferable.

[0047] If the grinding process is carried out in a wet manner, the suspension may be subjected to the next step, the carbonation step. It may be served after being dried.

[0048] As described above, the preparation process consists of a selection of a small number of steps from the group consisting of a sieving process and a grinding process. By performing at least one process, it is possible to obtain a product that contains a high content of free CaO and carbon dioxide. A CaO-containing composition with high reaction activity can be suitably prepared.

[0049] (CaO-containing composition) In the preparation step, the CaO-containing composition has a free CaO content of 50% by mass. Therefore, it is suitable for the production of calcium-based carbonate compounds. CaO content composition The material is preferably a sieved or pulverized product of a CaO-containing raw material, as described above. Even if the product has been sieved, it may have gone through a grinding process, and even if the product has gone through a sieving process good.

[0050] The free CaO content in a CaO-containing composition should be 50% by mass or more, The lower limit is preferably 60% by mass, more preferably 70% by mass, and even more preferably 75% by mass. A concentration of 80% by mass is particularly preferred. The higher the upper limit of the free CaO content, the better. However, it may be 98% by mass, 95% by mass, or 92% by mass. It is also fine to use 90% by mass.

[0051] The average particle size of the CaO-containing composition determined by laser diffraction is 1 μm or more and 30 μm or less. Preferably, it is 1.5 μm or more and 20 μm or less, and more preferably 2 μm It is even more preferable that the particle size be 10 μm or less. This allows for a reaction activity with carbon dioxide. A composition with a high CaO content can be obtained.

[0052] The BET specific surface area of ​​the CaO-containing composition is 10 m². 2 / g or more 50m 2 / g or less It is preferable that 12m 2 / g or more 40m 2 It is more preferable that it be less than or equal to / g, 15m 2 / g or more 30m 2 It is even more preferable that it be less than / g. A CaO-containing composition with high reaction activity can be obtained.

[0053] The upper limit of the ignition loss for the CaO-containing composition is preferably 40% by mass, and 35% by mass. It is more preferable that it be 30% by mass. The loss on ignition is small. While this is preferable, it may be 1% by mass, 3% by mass, or 5% by mass. That is acceptable. Loss on ignition mainly comes from water and CO2.

[0054] The SiO2 content in the CaO-containing composition is 0.4% by mass or more and 5.0% by mass or less. It is preferable that the amount is 0.6% by mass or more and 4.5% by mass or less, and more preferably 0.8 It is even more preferable that the amount is between 4.0% by mass and 4.0% by mass.

[0055] The Fe2O3 content in the CaO-containing composition is 0.14% by mass or more and 0.80% by mass or less. It is preferable that the amount is 0.16% by mass or more and 0.60% by mass or less. Furthermore, it is more preferable that the amount is between 0.18% by mass and 0.40% by mass.

[0056] The Al2O3 content in the CaO-containing composition is 0.2% by mass or more and 1.8% by mass or less. It is preferable that the amount be 0.3% by mass or more and 1.5% by mass or less, and more preferably 0. It is even more preferable that the amount is 4% by mass or more and 1.2% by mass or less.

[0057] The SO3 content in the CaO-containing composition is 0.8% by mass or more and 3.0% by mass or less. Preferably, it is 0.9% by mass or more and 2.5% by mass or less, and 1.0% by mass. It is even more preferable that the amount is between % by quantity and 2.0% by mass.

[0058] The hydrochloric acid-insoluble content of the CaO-containing composition shall be 1.0% by mass or more and 16.0% by mass or less. Preferably, it is 1.5% by mass or more and 14.0% by mass or less, more preferably 2.0% by mass It is even more preferable that the amount is between % and 12.0% by mass.

[0059] The upper limit of the CO2 content in the CaO-containing composition is preferably 30% by mass, It is more preferable that it be 0% by mass, and even more preferable that it be 10% by mass. While a lower content is preferable, it may be as low as 0.1% by mass, or as low as 0.2% by mass. It may be 0.3% by mass. CO2 mainly originates from calcium carbonate. By keeping this value low, the free CaO content can be improved.

[0060] (Carbonation process) In the carbonation process, the CaO-containing composition from the preparation process and carbon dioxide (hereinafter referred to as "carbon dioxide gas") Also known as ), it brings into contact with ) to form calcium-based carbonate compounds. The carbonation method is particularly While not limited to these, typically, a dispersion of a CaO-containing composition in water contains carbon dioxide. A carbon dioxide method, in which carbon dioxide is produced by blowing in air, is preferred.

[0061] The solid content concentration of the CaO-containing composition in the dispersion should be set appropriately considering the carbonation efficiency. Ideally, it should be between 10g / L and 500g / L (Ca concentration of 5.4% or more). Preferably 0% or less, and 20 g / L to 400 g / L (10.8% or less as Ca concentration). (21.6% or less) is more preferable, and 30 g / L or more and 350 g / L or less (as Ca concentration) A concentration of 16.2% to 18.9% is even more preferable. The sieving and grinding processes are carried out dry. In that case, the obtained CaO-containing composition can be dispersed in water to achieve the aforementioned concentration range. When the sieving and grinding processes are carried out wet, the concentration of the resulting CaO-containing composition suspension is The solution should be used by adding or removing water to achieve the specified concentration range.

[0062] Carbon dioxide used in the carbon dioxide process is used in calcium carbonate compound manufacturing plants, etc. The exhaust gas from the flue of the lime calcination furnace located nearby, as well as from combustion engines such as boilers and waste incinerators, The exhaust gas containing carbon dioxide emitted can be utilized.

[0063] The carbon dioxide concentration in the exhaust gas during the carbonation process is set to 1 volume%, taking carbonation efficiency into consideration. Preferably, the volume percentage is 50% or less, and preferably 3% to 40%. Preferably, the amount is 5% by volume or more and more than 30% by volume or less.

[0064] The temperature in the carbonation process (the temperature of the dispersion) is set to 5°C or higher, taking into consideration the carbonation efficiency. It is preferable that the temperature is 5°C or lower, more preferably 15°C or higher and 85°C or lower, and 25 It is even more preferable that the temperature is between 75°C and 75°C.

[0065] Regarding the flow rate of carbon dioxide, considering the carbonation efficiency and production capacity, the amount of raw material C added is... For aO, the flow rate is preferably 10 L / min to 200 L / min per 10 kg, and 20 L / min A flow rate of 180 L / min or more is more preferable, and 30 L / min or more is preferable to 150 L / min. It is preferable.

[0066] In the carbonation process, it is preferable to stir the mixture while simultaneously blowing in carbon dioxide. When using impellers for agitation, a rotation speed of 100 rpm to 600 rpm is preferred. More preferably between 150 rpm and 550 rpm, and between 200 rpm and 500 rpm. m or less is even more preferable.

[0067] The carbonation reaction time is determined by considering the concentration of the CaO-containing composition, the concentration of carbon dioxide, the flow rate, etc. The reaction time for carbonation is not limited; it should be set appropriately to allow the oxidation reaction to proceed sufficiently. The time is preferably 0.5 hours or more and 20 hours or less, and preferably 1 hour or more and 18 hours or less. A duration of 15 hours or more is even more preferable.

[0068] In addition to the carbon dioxide method described above, Na is reacted with an alkali (NaOH, amine, etc.) and CO2. First, 2CO3 or an amine carbonate is prepared, and then it is reacted with CaO to produce CaCO3. A solution-based method is also suitable.

[0069] Through the above process, the calcium carbonate as a carbon oxide of the CaO-containing composition is obtained. Compounds can be produced. The obtained calcium carbonate compound is filtered and dried into a powder. It can also be used in powder form, and calcium can be used in slurry or cake form without filtration or drying. It may also be used as a source of carbonate compounds.

[0070] <Calcium-based carbonates>

[0071] The average particle size of calcium-based carbonate compounds measured by laser diffraction is between 1 μm and 30 μm. It is preferable that it be below, more preferably 1.5 μm or more and 20 μm or less, and 2 μm It is even more preferable that the size is between m and 10 μm. This allows for calcium carbonate compounds It can improve the physical properties of the object to which it is applied.

[0072] The BET specific surface area of ​​calcium carbonate compounds is 2 m². 2 / g or more 25m 2 / g or less It is preferable that 4m 2 / g or more 20m 2 It is more preferable that it be less than or equal to / g, 6m 2 / g or more 15m 2 It is even more preferable that it be less than / g. This allows for calcium-based carbonation. The properties of the object to which the compound is applied can be improved.

[0073] The upper limit of the ignition loss of calcium carbonate compounds is preferably 55% by mass, and 50 It is more preferably mass% and even more preferably 45 mass%. The lower limit of the amount is preferably 30% by mass, and more preferably 35% by mass. It is even more preferable that the concentration be 40% by mass. This allows for the application of calcium-based carbonate compounds. The physical properties of the target object can be improved. Furthermore, the range is calcium carbonate compounds. It is preferable in terms of purity.

[0074] The CaO content in calcium carbonate compounds is between 40% and 65% by mass. It is preferable that the amount be 45% by mass or more and 60% by mass or less, and more preferably 50% by mass It is even more preferable that the amount is 55% by mass or less.

[0075] The SiO2 content in calcium-based carbonate compounds is 0.20% by mass or more and 2.00% by mass. Preferably, the amount is as follows, and more preferably 0.40% by mass or more and 1.80% by mass or less. More preferably, the amount is between 0.60% by mass and 1.60% by mass.

[0076] The Fe2O3 content in calcium carbonate compounds is 0.12% by mass or more and 1.20% by mass or more. It is preferable that it be % or less, and more preferably 0.14% by mass or more and 1.00% by mass or less. Preferably, the amount is 0.15% by mass or more and more than 0.80% by mass or less.

[0077] The Al2O3 content in calcium carbonate compounds is 0.10% by mass or more and 1.50% by mass. It is preferable that it be % or less, and more preferably 0.20% by mass or more and 1.20% by mass or less. Preferably, the amount is 0.30% by mass or more and more than 1.00% by mass or less.

[0078] The SO3 content in calcium-based carbonate compounds should be 0.75% by mass or more and 2.00% by mass or less. It is preferable that the amount is below the limit, and more preferably 0.80% by mass or more and 1.60% by mass or less. Furthermore, it is more preferable that the amount is between 0.85% by mass and 1.40% by mass.

[0079] The hydrochloric acid-insoluble content of calcium carbonate compounds is 0.4% by mass or more and 12.0% by mass or less. It is preferable that it be 0.7% by mass or more and 10.0% by mass or less, It is even more preferable that the amount is between 0.9% by mass and 8.0% by mass.

[0080] The lower limit of the CO2 content in calcium-based carbonate compounds is 25% by mass or more and 55% by mass or less. It is preferable that it be 30% by mass or more and 50% by mass or less, and 35 It is even more preferable that the amount is between 45% by mass and 45% by mass. CO2 is mainly calcium carbonate. It originates from this. By setting this value to the aforementioned range, the target of calcium carbonate compounds It can improve physical properties (for example, fire resistance when applied to inorganic molded materials).

[0081] The higher the rate of production of calcium-based carbonates that contribute to carbon dioxide sequestration, the better. Preferably, the lower limit is preferably 60% by mass, more preferably 70% by mass, and 80% by mass. This is even more preferable. The upper limit of the production rate is preferably 100% by mass, but 98% by mass is also preferable. It may be 95% by mass, or 90% by mass.

[0082] The lower the content of unreacted CaO in the calcium carbonate compound, the better. The upper limit is preferably 8% by mass, more preferably 6% by mass, and even more preferably 4% by mass. 2% by mass is particularly preferred. The lower limit of the unreacted CaO content is preferably 0% by mass. It may be 0.05% by mass, 0.1% by mass, or 0.2% by mass. That's fine.

[0083] In light of the synthesis procedure, the aforementioned calcium carbonate compound is a synthetic calcium carbonate compound. Preferably, as a calcium carbonate compound, a CaO-containing composition and carbon dioxide (carbon dioxide) By using synthetic calcium-based carbonate compounds, which are reaction products with carbon, industrial processes can be improved. By doing so, the secondarily generated carbon dioxide can be reused, and carbon dioxide throughout the industrial process can be reduced. This can contribute to reducing carbon emissions.

[0084] <Uses of calcium carbonate compounds> The applications of calcium carbonate compounds are not particularly limited. For example, they can be used in building materials. It is suitable as a high-performance additive for inorganic molded products, such as those mentioned above, and as a filler for resins. This section describes an embodiment in which calcium-based carbonate compounds are used in inorganic molded articles.

[0085] <Inorganic molded material> The inorganic molded material is not particularly limited, but typically includes molded boards and concrete used as building materials. Examples include concrete structures (molded concrete bodies), etc. The following describes the applicable compositions, etc., depending on the application. I will elaborate on this.

[0086] (Molded board for building materials) The molded board preferably consists of a hydraulic material, a siliceous material, a reinforcing fiber material, and a calcium-based carbonate Includes mixed ingredients.

[0087] (hydraulic material) Examples of hydraulic materials include cementitious materials, gypsum, lime, and slag. As for the material, commonly used cement, for example, ordinary Portland cement, High cement, moderate-heat cement, fly ash cement, blast furnace slag cement, and aluminum Examples include anhydrous gypsum, hemihydrate gypsum, and dihydrate gypsum. Examples of slag include blast furnace slag and converter slag. These hydraulic materials are 1 The seeds can be used individually or in combination of two or more species.

[0088] The hydraulic material content shall be 5% by mass or more, based on the total amount of materials constituting the molded plate. Preferably less than % by mass, more preferably 8% to 42% by mass, and 10% to 4% by mass. A content of 0% by mass or less is even more preferable. By keeping the hydraulic material content within the above range, the molded plate This can improve physical properties such as bending strength and peel strength, and also increase the bulk density of the molded sheet. This can suppress noise and improve work efficiency during construction.

[0089] (siliceous material) Examples of siliceous materials include silica sand, silica powder, silica fume, fly ash, and diatoms. Soil, layered silicates (e.g., mica, talc, kaolin, bentonite), wollastonite Lightweight aggregates (e.g., fly ash balloons, perlite, shirasu balloons, glass balloons) Examples include materials containing a large amount of SiO2, such as foams. These siliceous materials are selected individually. It can be used alone or in combination of two or more types. Talc, mica, and walnut. It can also be used as a reinforcing fiber material, as described later.

[0090] The silicate content is 10% by mass or more, based on the total amount of material constituting the molded board. Preferably 5% by mass or less, more preferably 12% by mass or more and 50% by mass or less, and 15% by mass or less A content of 45% by mass or less is even more preferable. If the content of siliceous material is within the above range, the molded plate It becomes possible to set bending strength, bulk density, water absorption rate, dimensional stability, etc., within the desired range. Oh, as siliceous materials, units such as perlite, fly ash balloons, and shirasu balloons. Volume mass is 0.5 g / cm³ 3 When the following lightweight aggregates are used in the mixture, the bulk density becomes too light, causing bending. To prevent a decrease in strength such as peel strength and other properties, the entire amount of material constituting the molded plate is based on As a standard practice, other silicate materials should be used in combination so that the lightweight aggregate content is 20% by mass or less. This is preferable.

[0091] (Reinforcement fiber material) Examples of reinforcing fiber materials include softwood pulp, hardwood pulp, and fibrillated pulp. Pulps such as pulp from defibrated waste paper, vinylon fibers, and acrylonitrile fibers. Organic reinforcing fiber materials such as polypropylene fibers, inorganic reinforcing fibers such as rock wool and glass fibers Fiber materials can be used. These reinforcing fiber materials can be used individually or in combination of two or more types. They can be used in combination.

[0092] To improve the strength and toughness of the molded plate, the content of reinforcing fiber material is determined by the composition of the molded plate. Based on the total amount of material, it is preferable that it be 2% by mass or more and 30% by mass or less, and 3% by mass or more and 26% by mass It is more preferable that the amount be % or less, and even more preferable that it be 4% by mass or more and 22% by mass or less. It is desirable. By keeping the content of the reinforcing fiber material within the aforementioned range, a sufficient reinforcing effect can be achieved. This can suppress the protrusion of fibers on the surface of the molded plate, thereby improving smoothness. Average length When incorporating inorganic reinforcing fiber materials of 1 mm to 50 mm in thickness as reinforcing fiber material, the molded plate To ensure good smoothness, the total amount of material constituting the molded plate is used as the basis, and its content is 1 It is preferable to use other reinforcing fiber materials in combination so that the amount is 0% by mass or less.

[0093] (Calcium-based carbonate compounds) As the calcium carbonate compound, the above-mentioned calcium carbonate compound is preferably used. It is possible.

[0094] The calcium carbonate content is based on the total amount of material constituting the molded board, using five different types of calcium carbonate as the basis. Preferably % by mass or more and 60% by mass or less, more preferably 8% by mass or more and 55% by mass or less, 12 A mass of % or more and 50% or less is more preferable. A low thermal conductivity calcium-based carbonate compound is used as a precursor. By blending the material within the specified range, the strength and fire resistance of the molded sheet can be improved.

[0095] (optional ingredient) In addition to the aforementioned materials, the molded board may also contain resin hollow bodies, wood chips, and wood powder to impart various functions. , resin powder, defoaming agent, flocculant, water repellent, thickener (methylcellulose, hydroxyethyl methylcellulose) Materials such as cellulose (including hydroxypropyl methylcellulose) and dispersants are used for the intended purpose. Various formulations can be used depending on the situation. In addition, scraps and other materials generated during the processing of molded plates can be used as powder. It is also possible to use the product by adding crushed recycled material as needed.

[0096] The bulk density of the molded plate is 0.7 g / cm³. 3 More than 2.0g / cm 3 The following is preferable Mashiku, 0.8 g / cm³ 3 More than 1.8g / cm 3 It is more preferable that it be 0.9 g / cm 3 More than 1.6g / cm 3 The following is even more preferable:

[0097] (Method of manufacturing molded boards) The method for manufacturing the molded plate according to this embodiment is not particularly limited and is generally used. Papermaking, extrusion molding, flow-on molding, slip molding, press (compression) molding, etc. It can be used. The molded plate is made by pressing and dewatering the green sheet formed by these methods. Alternatively, after applying a pattern using embossing or other methods, curing is performed using methods such as room temperature curing, steam curing, or autoclave curing. It can be obtained by curing. Furthermore, drying is performed, and shaping and painting can be done as needed. That's fine.

[0098] (Uses of molded sheets) The uses of molded boards are not particularly limited and include wall materials, flooring materials, roofing materials, various boards, exterior decorative components, etc. It is preferred as a performance maintenance material for interior and exterior finishing materials such as joinery, sealants, insulation materials, sound-absorbing materials, and waterproofing materials. It can be used appropriately. The molded board is a cement-based molded board containing cementitious material. This is preferred, and a calcium silicate molded product is more preferred.

[0099] (Concrete structure) Concrete structures are composed of hardened bodies of hydraulic compositions. Hydraulic compositions are made of In addition to calcium carbonate compounds, the following are also used: blast furnace slag, expansive material, slaked lime, quicklime, and fly ash. It consists of a powder containing at least one of the following: calcium and Portland cement. As the calcium carbonate compound, the calcium carbonate compounds mentioned above can be suitably used. .

[0100] In addition to the above hydraulic composition, aggregates such as sand and gravel, chemical admixtures for concrete, etc. A hydraulic composition mixed material may be formed by incorporating metals, polymer materials, or other fibrous materials.

[0101] The hardened body of the hydraulic composition is obtained by hardening a paste obtained by kneading water into the hydraulic composition. Furthermore, the hardened body of the hydraulic composition mixed material is made by adding water to the above hydraulic composition mixed material. The mixture obtained by mixing (equivalent to fresh mortar or fresh concrete) is hardened. It is a material equivalent to mortar or concrete.

[0102] The proportion of calcium carbonate compounds in the powder (calcium carbonate compounds relative to cement) The proportion of the substance is in the range of 1% to 60% by mass, preferably 3% to 50% by mass, and further Preferably, the amount is in the range of 5% to 40% by mass.

[0103] Blast furnace slag is used in JIS (Japanese Industrial Standards) R5211 "Blast Furnace Cement". Blast furnace slag fine powder or blast furnace conforming to JIS A6206 "Blast furnace slag for concrete" It is preferable to use slag fine powder. Also, blast furnace slag has a specific surface area of ​​2000 to 10 000cm 2 / g, preferably 3500-7000cm 2 Use the one that is / g That is preferable.

[0104] Expansion agents include, for example, those specified in JIS A6202 "Expansion Agents for Concrete" Use the material. The expansive agent should be added at a ratio of 2 to 9% by mass relative to the total hydraulic composition. That would be preferable.

[0105] For slaked lime, for example, use the type specified in JIS R9001 "Industrial Lime". That's fine. Also, quicklime turns into slaked lime when it comes into contact with water, for example, JIS R9001 Quicklime, as defined in "industrial lime," can be used as a substitute for slaked lime. In that case, it is advisable to adjust the amount of water required when quicklime is converted into slaked lime. Fly ash includes, for example, JIS A6201 "Fly ash for concrete". Use the one that is suitable.

[0106] Portland cement is usually used, but Portland C Other types of cement include rapid-hardening Portland cement, ultra-rapid-hardening Portland cement, and moderate-heat cement. Portland cement, low-heat Portland cement, sulfate-resistant Portland cement, etc. As specified in JIS R5210 "Portland cement", and JIS R5214 "Eco Cement" can also be used.

[0107] If the hydraulic composition contains Portland cement, then, other than calcium carbonate compounds, The proportion of Portland cement in the powder shall be 70% by mass or less, and 30% by mass or less. This is preferable.

[0108] Furthermore, when using Portland cement and blast furnace slag or fly ash, The component in question is pre-mixed, for example, JIS R5211 "Blast Furnace Cement", or, for example For example, JIS R5213 "Fly Ash Cement" can be used individually or in combination. It may also be used in this way.

[0109] Since a calcium-based carbonate compound having the above characteristics is used, hydraulic compositions and hydraulic compounds The compound mixture exhibits good fluidity, and the resulting hardened concrete has excellent compressive strength. It can demonstrate its capabilities.

[0110] The density of the aforementioned concrete structure is 0.7 g / cm³. 3 More than 2.0g / cm3 is as follows is preferable, 0.8 g / cm 3 or more and 1.8 g / cm 3 is more preferably as follows , 0.9 g / cm 3 or more and 1.6 g / cm 3 is even more preferably as follows.

Example

[0111] 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, etc. were carried out as follows . The following analysis was performed on each of the CaO-containing composition and calcium-based carbonate compound (hereinafter, both are also referred to as "sample") obtained in the examples and comparative examples. When the sample was a suspension, the filtered wet product was dried at 110 °C for 12 hours and used for evaluation. The analysis results of the CaO-containing composition are shown in Table 1, and the analysis results of the calcium-based carbonate compound are shown in Table 2. SEM photographs of the calcium-based carbonate compound are shown in FIGS. 2 to 5 .

[0112] <Evaluation of CaO-containing composition and calcium-based carbonate compound> For each of the CaO-containing composition and calcium-based carbonate compound (hereinafter, both are also referred to as "sample") obtained in the examples and comparative examples, the following analysis was performed. When the sample was a suspension, the filtered wet product was dried at 110 °C for 12 hours and used for evaluation. The analysis results of the CaO-containing composition are shown in Table 1, and the analysis results of the calcium-based carbonate compound are shown in Table 2. SEM photographs of the calcium-based carbonate compound are shown in FIGS. 2 to 5 . When the sample was a suspension, the filtered wet product was dried at 110 °C for 12 hours and used for evaluation. The analysis results of the CaO-containing composition are shown in Table 1, and the analysis results of the calcium-based carbonate compound are shown in Table 2. SEM photographs of the calcium-based carbonate compound are shown in FIGS. 2 to 5 .

[0113] (Loss on ignition) Approximately 2 g of the sample was put into a porcelain crucible that had been weighed and made constant in advance, and the total mass was precisely weighed . This was heated in an electric furnace at 900 °C ± 25 °C for 3 hours or more. It was cooled to room temperature in a desiccator and precisely weighed, and the difference in mass before and after heating was determined as the loss amount. Based on the following formula, the loss on ignition (mass basis) was determined . L (%) = (D / S) × 100 (In the formula, L is the loss on ignition (%). D is the loss amount (g). S is the weight of the sample before heating (g).)​

[0114] (Calcium oxide content) The "ethylenediaminetetraacetic acid disodium titration method", which is a method for measuring the content ratio of calcium carbonate in the calcium-based carbonate compound, was used for treatment, and the content ratio (% by mass) of CaO in the sample was determined by the following formula. ethylenediaminetetraacetic acid disodium titration method", and the content ratio (% by mass) of CaO in the sample was determined by the following formula. was determined.

[0115]

Equation

[0116] (Contents of SiO2, Fe2O3, Al2O3 and SO3) <ICP-AES method> Weighed 0.2 g of the sample, moistened it with water, added 14 mL of hydrochloric acid (a solution obtained by mixing concentrated hydrochloric acid and water in a volume ratio of 1:1) with a pipette, and heated and dissolved it. After cooling, it was transferred to a 100 mL volumetric flask, and water was added to make up to 100 mL. From this, 5 mL was taken and placed in a 50 mL volumetric flask, and water was added to make up to 50 mL to obtain a measurement test solution. On the other hand, 5 mL was taken from the 10 0 mL of the made-up aqueous solution and placed in a 50 mL volumetric flask, and standard solutions of each element (Si , Fe, Al and S) were arbitrarily added to prepare calibration standard solutions with different concentrations. The standard solutions of each element were prepared using 1000 ppm atomic absorption standard solutions (commercially available). 0 mL of the made-up aqueous solution and placed in a 50 mL volumetric flask, and standard solutions of each element (Si , Fe, Al and S) were arbitrarily added to prepare calibration standard solutions with different concentrations. The standard solutions of each element were prepared using 1000 ppm atomic absorption standard solutions (commercially available). , Fe, Al and S) were arbitrarily added to prepare calibration standard solutions with different concentrations. The standard solutions of each element were prepared using 1000 ppm atomic absorption standard solutions (commercially available). Calibration standard solutions with different concentrations obtained by adding each element and the measurement test solution were subjected to inductively coupled plasma luminescence spectrometry (ICP-AES) apparatus (manufactured by Hitachi High-Technologies Corporation, "SPECTR

[0117] luminescence spectrometry (ICP-AES) apparatus (manufactured by Hitachi High-Technologies Corporation, "SPECTR luminescence spectrometry (ICP-AES) apparatus (manufactured by Hitachi High-Technologies Corporation, "SPECTR Set the sampler in the OBLUE FMS36 autosampler and sample Si and Fe under the following conditions. The amounts of Al and S (ppm) were measured. <Measurement conditions> High-frequency output: 1.4kW Carrier gas (humidification) flow rate: 0.9 L / min Plasma gas flow rate: 13.0 L / min Auxiliary gas flow rate: 1.0 L / min pH: Aqueous solution Number of integrations: 3 Sample order: per sample Measurement method: Standard addition method Weighting of calibration curve: None Measurement wavelength: Si: 251.612nm Fe: 238.204nm Al: 167.078nm S:182.034nm

[0118] Finally, the content (mass %) of each element is calculated from the obtained amounts of each element, and then converted to oxide values. The content (mass%) of SiO2, Fe2O3, Al2O3, and SO3 was then determined.

[0119] (Hydrochloric acid insoluble content) Weigh 5.00g of the sample into a 200mL beaker, moisten with water, and then add hydrochloric acid (concentrated hydrochloric acid and water). Add 50 mL of a solution (a mixture of [ingredients] in a 1:1 volume ratio), heat to approximately 100°C, and cook for approximately 5 minutes. It dissolved. This solution was filtered using No. 5B filter paper while still warm. Inside the beaker Insoluble material adhering to the wall can be removed using a policeman (a laboratory instrument with a rubber-covered tip on a glass rod). The material was scraped off and collected, then combined with the insoluble material on the filter paper. The insoluble material on the filter paper was heated in warm water at approximately 70°C for 3 minutes. Washed with 00 mL or more. Insoluble matter was dried together with the filter paper and placed in a porcelain crucible and heated. It was burned above. Furthermore, it was heated in an electric furnace (900°C) for more than 20 minutes to incinerate it. It was removed from the furnace and cooled on a porcelain dish. Using plastic tweezers, it was placed in a porcelain crucible (containing insoluble material). The crucible was placed on a precision balance and zero-point correction was performed (load set to zero). Insoluble material was extracted from the porcelain crucible. Removed with a brush, and then placed back on a precision balance to weigh the reduced amount (indicated by a negative mark on the scale). The quantity corresponds to the mass of the hydrochloric acid-insoluble portion. The hydrochloric acid-insoluble portion (mass%) was calculated using the following formula. H(mass%)=(|R| / S)×100 (In the formula, H is the insoluble portion of hydrochloric acid (mass%). R is the amount lost when the insoluble matter is removed (g) Yes, it exists. S is the weight of the sample (g).

[0120] (CO2 content) The reagents used for the measurement were prepared as follows. • 1 / 10N barium hydroxide solution: 15.8g of barium hydroxide (octahydrate) in ultrapure water Dissolve in 1000 mL to make a total volume. After sealing tightly and shaking well, let stand for at least one day, and then remove the supernatant. The liquid was portioned out and used as the solution in question. • Sulfuric acid: A solution was prepared by mixing concentrated sulfuric acid and water in a 1:1 volume ratio. • 1 / 10N hydrochloric acid standard solution: Prepared by diluting 1N hydrochloric acid 10 times. • PP indicator: Dissolve 1 g of phenolphthalein in ethanol to make a total of 100 mL. .

[0121] Figure 1 is a schematic diagram showing a device for measuring CO2 content. Inside the measuring device is a circulation pump. The gas was circulating, and an airtight state was maintained during circulation. In the diagram, the arrows indicate the direction of gas flow. To indicate direction.

[0122] Using the measuring apparatus shown in Figure 1, the CO2 content was determined by the following procedure: 1 / 10N hydroxide Distribute 20.0 mL of barium solution into a 100 mL medium bottle, and add 2 drops of PP indicator to it. The bottle was sealed. Separately, 0.1g of the sample was taken into a 500mL medium bottle, and the total volume was 20 Water was added until the total volume was 0 mL. Using a measuring cup, 10 mL of sulfuric acid was added to the dish, and immediately The bottle was sealed and the circulation pump was activated. After running it for more than 90 minutes, the medium bottle 100 The sample was removed from the instrument and titrated directly with 1 / 10N hydrochloric acid standard solution. The same procedure was repeated without adding the sample to a 500 mL vial of Dium, and this was used as a control. The following formula was used: Based on this, the CO2 content (mass %) was determined.

[0123]

number

[0124] (Content of free CaO in CaO-containing compositions) The free CaO content Z (mass%) in the CaO-containing composition is determined by the ignition loss and C calculated above. The calculation was performed using the following formula, based on data for aO content, SO3 content, and CO2 content. The "%" in this case represents "mass%".

[0125]

number

[0126] (BET specific surface area) Using an 8 - unit pre - heater unit (manufactured by MOUNTECH), in a nitrogen gas atmosphere, about 1 The sample powder pretreated at 30 °C for about 30 minutes was measured for BET specific surface area using Macso rb HM Model - 1208 (manufactured by MOUNTECH) by the nitrogen gas adsorption method to measure the BET specific surface area (m 2 / g).

[0127] (Average particle size 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 (Tommy Seiko Co., Ltd. UD - 20 1) was carried out for 3 minutes to prepare a dispersion liquid. This dispersion liquid was measured using a laser diffraction method - particle size distribution meter (Microtrac HRA Model 9320 - X100 manufactured by Nikkiso Co., Ltd.) to measure the volume - based D value as the average particle size (μm). 50

[0128] (Production rate of calcium - based carbonate compounds contributing to carbon dioxide fixation) The production rate E (mass%) of calcium - based carbonate compounds contributing to carbon dioxide fixation was determined from the following formula . [Equation] (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 Ca O - containing composition.)

[0129] (Content rate of unreacted CaO in calcium - based carbonate compounds) The content rate G (mass%) of unreacted CaO in calcium - based carbonate compounds was determined from the following formula . [Equation]​ (In the formula, g is the CaO content rate (mass %) in the calcium-based carbonate compound. h is the CO2 content rate (mass %) in the calcium-based carbonate compound. i is the SO3 content rate (mass %) in the calcium-based carbonate compound.)

[0130] (Scanning electron microscope observation) A double-sided tape was attached to the aluminum sample stage, and the sample powder was spread on it with a spatula blade so as to be thinly spread. After platinum evaporation, a photograph of the particle image of the sample powder was taken at 5,000 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. 2 to 5.

[0131] <Preparation of CaO-containing Composition and Production of Calcium-based Carbonate Compound> [Example 1-1] 20 L of water was poured into a 30 L plastic container, and 1.5 kg of lime sludge (hydrated lime-based wet product) was added under stirring and stirred for 1 hour. Then, screening was performed with a sieve having a mesh size of 4 mm by the wet method. After the suspension passing through the sieve was allowed to stand for 1 hour, about 10 L of the supernatant was removed and concentrated to 10 L of a suspension having a solid content concentration of about 130 g / L. 10 L of this suspension was put into a 20 L capacity pot mill filled with 5 kg of zirconia balls with a diameter of 8 mm and wet pulverized at a rotation speed of 90 rpm for 4 hours to prepare a CaO-containing composition. For analysis, after filtering this slurry, a wet product dried at 110 °C for 12 hours was used.

[0132] The pulverized slurry was taken out from the pot mill and 6 L of the pulverized slurry with a solid content concentration of 130 g / L was charged into an 8 L capacity SUS container with a baffle plate. Then, the temperature was raised to 40 °C and under that temperature Using a stirrer equipped with a single-stage turbine blade, stirring was carried out at a rotational speed of 350 rpm. LNG was used as fuel An exhaust gas extraction pipe was connected to the exhaust outlet of a boiler for steam production using the exhaust gas, and a test blower was used to draw in the exhaust gas. When measured with a CO2 concentration measuring device (XP-3 140 manufactured by Shin Cosmos Electric Co., Ltd.), the CO2 concentration in the exhaust gas showed 10% by volume. In the above-mentioned 8L capacity SUS container, the exhaust gas was introduced at a speed of 3.3 L / min using a test blower and reacted for 1 0 hours. Next, it was filtered, and the filtered wet product was dried at 110 °C for 12 hours and pulverized [[ID=...]]to obtain a sample powder of calcium-based carbonate compound.

[0133] [Example 1-2] 2 kg of lime sludge (dry product of quicklime) was dried at 110 °C for 12 hours to produce a dried product, and dry pulverization was carried out at a feeding rate of about 100 g / min of the dried product using a bantam mill to obtain a dry pulverized product as a CaO-containing composition. In an 8L capacity SUS container with a baffle plate filled with 6L of water, except that 780 g of the above-mentioned dry pulverized product was charged, the same operation as in Example 1 was carried out to obtain a sample powder of calcium-based carbonate compound.

[0134] [Example 1-3] The suspension of the fraction passing through a sieve with a mesh opening of 4 mm was used as a CaO-containing composition and directly used in the carbonation reaction except for this, the same operation as in Example 1 was carried out to obtain a sample powder of calcium-based carbonate compound.

[0135] [Comparative Example 1-1] Except that the suspension of the fraction on the sieve was used instead of the fraction passing through a sieve with a mesh opening of 4 mm, the same operation as in Example 1 was carried out to obtain a CaO-containing composition and a sample powder of calcium-based carbonate compound.

[0136]

Table 1

[0137] [Table 2]

[0138] From the results in Tables 1 and 2, the content of free CaO in the CaO-containing composition of the example, and C The production rates of calcium-based carbonate compounds that contributed to O2 immobilization were all higher compared to the comparative example. It was a value.

[0139] <Manufacturing of inorganic molded products> Inorganic molded articles were manufactured by papermaking according to the following procedure. The proportions of the components used were as follows: Unless otherwise indicated, all measurements refer to "parts by mass". In the table below, "-" indicates that the corresponding component was not used. This indicates that.

[0140] [Example 2-1] Production of inorganic molded articles by papermaking method The materials shown in Table 3 below were placed in a plastic container and stirred to obtain a raw material slurry. Calcium The calcium-based carbonate compound from Example 1-1 was used as the carbonate compound. Felt was laid down. The raw material slurry is divided and put into the filter, and suction filtration is performed using a vacuum pump while the laminate is being filtered. A laminate (28mm long x 24mm short x 14mm thick) was fabricated. The laminate was removed from the filter. Dehydration pressing was performed. The thickness after pressing was 13 mm. Autoclave curing (curing) Pressure (gauge pressure): 9 kgf / cm² 2 After a curing time of 12 hours, the pressed body is placed in a dryer (105°C). It was dried at ℃ for 24 hours. Both sides were sanded with a sander to adjust the thickness to 12 mm, and inorganic A molded body was obtained.

[0141] [Example 2-2] Production of inorganic molded articles by papermaking method The calcium carbonate compounds used in Examples 1-2 were used as the calcium carbonate compounds. An inorganic molded body was obtained externally in the same manner as in Example 2-1.

[0142] [Examples 2-3] Production of inorganic molded articles by papermaking method As the calcium carbonate compounds used were the calcium carbonate compounds of Examples 1-3. An inorganic molded body was obtained externally in the same manner as in Example 2-1.

[0143] [Comparative Example 2-1] Production of inorganic molded articles by papermaking method As the calcium carbonate compound used was the calcium carbonate compound of Comparative Example 1-1. An inorganic molded body was obtained externally in the same manner as in Example 2-1.

[0144] [Comparative Example 2-2] Production of inorganic molded articles by papermaking method Except for not using calcium-based carbonate compounds, the inorganic materials were prepared in the same manner as in Example 2-1. A molded body was obtained.

[0145] <Evaluation of inorganic molded products> The inorganic molded articles produced by the papermaking method in the examples and comparative examples were evaluated as follows: The results are shown in Table 3.

[0146] (Bulk density) Bulk density was measured in accordance with JIS A 5430.

[0147] (Heating test) The heating test was performed using the following apparatus and procedure. Figure 6 is a schematic partial perspective view of the heating tester. As shown in Figure 6, an electric heater is used as the heat source and the temperature is stabilized at around 900°C. To enable this, a fire-resistant material was assembled between the test specimen and the heat source, and the temperature of the back surface of the test specimen was measured using a thermocouple. This was made possible to measure. Specifically, an electric heater (1.2kW heater) was used as the heat source equipment. The test specimen was fixed so that the distance between the heated surface and the heat source was approximately 70 mm.

[0148] The test procedure was as follows: (1) A sacrificial plate was placed, and preheating was performed to 902°C, after which heating was performed once. (2) The test specimen was replaced after the heated side had cooled to 200°C or below. (3) Place a thermocouple in the center of the back surface (top surface in the diagram) of the test specimen, and place a calcium silicate board (approximately 30m The sheet (m x 70mm) was fixed in place with a weight on top. (4) Start heating, leave for the specified time (45 minutes), and record the temperature of the front and back sides using a data logger. Record the data. During this time, the electric heater temperature setting will be 902°C on the heating surface side, with 900°C as the lower limit. The temperature was controlled by a temperature controller. The temperature measurement interval of the data logger was set to every 10 seconds, and data was collected at this interval. It recorded a "ta". (5) After the test is completed, remove the test specimen and measure the following items (each item was also measured before the test). I did it. • Dimensions: The length and width of the back surface and heating surface were measured with calipers. Area of ​​the heating surface before and after the test. (mm 2 The following formula was used to calculate the heat-induced surface shrinkage (%). Heating surface shrinkage (%) = {|S1-S0| / S0} × 100 (In the formula, S0 is the area of ​​the heated surface before the test (mm²) 2 ) and S1 is the heated surface after the test. Area (mm 2 ) is. ) • Warping: Place the test specimen on an iron surface plate and measure the height from the iron surface plate at the center of each side of the test specimen. The warp was measured using a gauge and the average value (mm) was taken. This average value was defined as the warp after heating (mm).

[0149] [Table 3]

[0150] In the inorganic molded articles of the examples, the heat-induced shrinkage, back surface temperature rise, and post-heat warping were all compared. It showed superior performance compared to the example and exhibited good fire resistance. Furthermore, in the inorganic molded body of the example, after heating... No cracks had formed (not shown).

Claims

1. A preparation step for preparing a CaO-containing composition having a free CaO content of 50% by mass or more, and Beauty The CaO-containing composition is brought into contact with carbon dioxide to form a calcium-based carbonate compound. Carbonation process A method for producing calcium-based carbonate compounds, including [the specified compound].

2. The aforementioned preparation step includes a sieving step in which the CaO-containing raw material is sieved and the portion that passes through the sieve is recovered. A method for producing the calcium carbonate compound described in item 1.

3. A method for producing a calcium carbonate compound according to claim 2, wherein the sieving step is performed in a wet manner.

4. The preparation step includes a grinding step of grinding the CaO-containing raw material, as described in claim 1. A method for producing um-based carbonate compounds.

5. The CaO-containing raw material is derived from waste from a process involving the calcination and smoldering of limestone. A method for producing a calcium-based carbonate compound according to any one of claims 2 to 4.

6. The average particle size of the CaO-containing composition determined by laser diffraction is 1 μm or more and 30 μm or less. The method for producing a calcium-based carbonate compound according to claim 1.

7. The BET specific surface area of ​​the CaO-containing composition is 10 m². ２ / g or more 50m ２ / g or less A method for producing a calcium-based carbonate compound as described in claim 1.

8. The carbon dioxide concentration in the carbonation process is 1% by volume or more and 50% by volume or less. A method for producing the calcium carbonate compound described in item 1.

9. The carbon dioxide used in the carbonation process is carbon dioxide emitted from the combustion engine. A method for producing the calcium carbonate compound described in item 1.

10. The calcium carbonate in the carbonation step is 5°C or higher and 95°C or lower, according to claim 1. A method for producing um-based carbonate compounds.

11. CaO for the production of calcium carbonate compounds, with a free CaO content of 50% by mass or more. Containing composition.

12. The CaO-containing composition according to claim 11, wherein the CaO-containing raw material is a sieved or pulverized product.

13. The CaO-containing raw material is derived from waste from a process involving the calcination and smoldering of limestone. The CaO-containing composition according to claim 12.

14. The calcium carbonate is a CaO-containing composition according to any one of claims 11 to 13. A um carbonate compound.

15. A calcium-based carbonate compound according to claim 14, for use in inorganic molded articles.

16. An inorganic molded article containing the calcium-based carbonate compound described in claim 14.

Images