Carbonated cement slurry production system

Abstract

The present invention provides a cement composition production system that can fix carbon dioxide in a cement composition.　A carbonated cement slurry production system 1 is for producing a carbonated cement slurry obtained by carbonating, with a carbon dioxide-containing gas, a cement slurry containing cement and water. The carbonated cement slurry production system 1 includes: a carbonation device 2 for bringing the carbon dioxide-containing gas into contact with the cement slurry 15; and a carbon dioxide-containing gas supply device 3 for supplying the carbon dioxide-containing gas to the carbonation device 2 at a pressure greater than the atmospheric pressure. The carbonation device 2 includes a carbonation tank 4 for housing the cement slurry 15 and the carbon dioxide-containing gas such that a gas phase comprising the carbon dioxide-containing gas is positioned above a liquid phase comprising the cement slurry.

Description

[Technical field]

[0001] The present invention relates to a system for producing a carbonated cement slurry. [Background technology]

[0002] In recent years, reducing carbon dioxide emissions has become an important issue in order to prevent global warming. In relation to this, technology is being considered for fixing carbon dioxide captured from exhaust gases generated in cement manufacturing plants into concrete, etc. As a method for providing concrete in which carbon dioxide is efficiently fixed, Patent Document 1 describes a method for producing concrete, which includes forming a first mixture containing cement and water, adding carbon dioxide to the first mixture to form a second mixture, and hardening the second mixture, and the weight of the water is adjusted so that the amount of unhydrated cement remaining in the concrete is between 0% and 50%. Furthermore, as a method for producing a cement powder composition using a calcium-containing powder that has absorbed carbon dioxide, Patent Document 2 describes a method for producing a cement powder composition containing cement clinker powder, gypsum powder, and carbonated calcium-containing powder, which includes a carbonation step of supplying a carbon dioxide-containing gas into a slurry containing the calcium-containing powder and water before carbonation to obtain a carbonated slurry, and a grinding step of supplying the cement clinker, gypsum, and the carbonated slurry into a finishing mill for cement production and grinding them to obtain the cement powder composition. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-37493 A [Patent Document 2] JP 2020-152631 A Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a system for producing a carbonated cement slurry that can fix carbon dioxide in a cement slurry efficiently and in a larger amount. [Means for solving the problem]

[0005] As a result of intensive research into solving the above problems, the present inventors have found that the above object can be achieved if there is a carbonated cement slurry production system for producing a carbonated cement slurry by carbonating a cement slurry containing cement and water with a carbon dioxide-containing gas, the carbonated cement slurry production system including a carbonation device for contacting the cement slurry with the carbon dioxide-containing gas, and a carbon dioxide-containing gas supply device for supplying the carbon dioxide-containing gas to the carbonation device at a pressure greater than atmospheric pressure, and the carbonation device includes a carbonation tank for storing the cement slurry and the carbon dioxide-containing gas such that a gas phase consisting of the carbon dioxide-containing gas is located above a liquid phase consisting of the cement slurry, and have completed the present invention. That is, the present invention provides the following [1] to

[12] .

[0006] [1] A carbonated cement slurry production system for producing a carbonated cement slurry by carbonating a cement slurry containing cement and water with a carbon dioxide-containing gas, the carbonated cement slurry production system including: a carbonation device for contacting the cement slurry with the carbon dioxide-containing gas; and a carbon dioxide-containing gas supply device for supplying the carbon dioxide-containing gas to the carbonation device at a pressure greater than atmospheric pressure, and the carbonation device including a carbonation tank for storing the cement slurry and the carbon dioxide-containing gas such that a gas phase composed of the carbon dioxide-containing gas is located above a liquid phase composed of the cement slurry. [2] The carbonated cement slurry production system according to [1], wherein the carbonation device has an inlet for the cement slurry and an inlet for the carbon dioxide-containing gas, and the carbonated cement slurry production system includes a mixing tank upstream of the carbonation device for mixing the cement and the water to obtain the cement slurry. [3] The carbonated cement slurry production system according to [2], further comprising a slurry circulation path for circulating the carbonated cement slurry between the carbonation device and the mixing tank.

[0007] [4] The system for producing carbonated cement slurry according to [1], wherein the carbonation device has an inlet for the cement, an inlet for the water, and an inlet for the carbon dioxide-containing gas. [5] The carbonated cement slurry production system according to [4], further comprising a slurry circulation path for returning a portion of the carbonated cement slurry discharged from the carbonation device to the carbonation device for circulating the same. [6] The carbonated cement slurry production system according to [1], further comprising: a mixing tank for mixing the cement and the water to obtain the cement slurry, on the upstream side of the carbonation device; and a storage tank for storing the cement slurry, on the downstream side of the mixing tank and upstream of the carbonation device; and a slurry circulation path for circulating the carbonated cement slurry between the carbonation device and the storage tank.

[0008] [7] The carbonated cement slurry production system according to any one of [1] to [6], further comprising a storage tank for storing the carbonated cement slurry obtained by the carbonation device. [8] The system for producing a carbonated cement slurry according to any one of [1] to [7], further comprising a solid-liquid separation means for recovering a part of water in the carbonated cement slurry obtained by the carbonation device. [9] The carbonated cement slurry production system according to [8], further comprising water return means for using the water recovered by the solid-liquid separation means as part of the water for preparing the cement slurry.

[10] The carbonated cement slurry production system according to any one of [1] to [9], further comprising a liquid temperature adjusting means for adjusting a liquid temperature of at least one of the cement slurry and the carbonated cement slurry.

[11] The carbonated cement slurry production system according to any one of [1] to

[10] , further comprising a pH measuring means for measuring a pH of at least one of the cement slurry and the carbonated cement slurry.

[0009]

[12] A method for producing a carbonated cement slurry by carbonating a cement slurry containing cement and water with a carbon dioxide-containing gas, comprising: a cement slurry preparation step of mixing the cement and the water to obtain the cement slurry; a cement slurry containing step of containing the cement slurry and the carbon dioxide-containing gas in a carbonation tank so that a gas phase consisting of the carbon dioxide-containing gas is located above a liquid phase consisting of the cement slurry; and a carbonated cement slurry preparation step of supplying the carbon dioxide-containing gas to the gas phase at a pressure greater than atmospheric pressure to bring the liquid phase and the gas phase into contact with each other, thereby carbonated the cement slurry to obtain a carbonated cement slurry. Effect of the Invention

[0010] According to the carbonated cement slurry production system of the present invention, it is possible to fix a larger amount of carbon dioxide efficiently in the cement slurry. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram showing an example of a carbonated cement slurry production system of the present invention, including a mixing tank. [Diagram 2] FIG. 2 is a schematic diagram showing an example of a carbonated cement slurry production system of the present invention that does not include a mixing tank. [Diagram 3] FIG. 1 is a diagram showing a schematic diagram of an example of a carbonated cement slurry production system of the present invention, including a mixing tank and a storage tank. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The carbonated cement slurry production system of the present invention is for producing a carbonated cement slurry by carbonating a cement slurry containing cement and water with a carbon dioxide-containing gas. The carbonated cement slurry production system of the present invention includes a carbonation device for contacting the cement slurry with the carbon dioxide-containing gas, and a carbon dioxide-containing gas supply device for supplying the carbon dioxide-containing gas to the carbonation device at a pressure higher than atmospheric pressure. The carbonation device includes a carbonation tank for storing the cement slurry and the carbon dioxide-containing gas such that a gas phase consisting of the carbon dioxide-containing gas is located above a liquid phase consisting of the cement slurry. In this specification, the term "carbonation" refers to the absorption and fixation of carbon dioxide. The details are explained below.

[0013] The carbonation device is equipped with a carbonation tank for storing cement slurry and carbon dioxide-containing gas (a gas containing carbon dioxide in gas form (hereinafter also referred to as "carbon dioxide gas")) so that the gas phase consisting of the carbon dioxide-containing gas is located above the liquid phase consisting of the cement slurry. In this specification, the term "liquid phase" has a concept that includes a slurry (specifically, a cement slurry) obtained by mixing a liquid with a powder or granular material (specifically, water and cement). In the carbonation tank, the cement slurry is brought into contact with a carbon dioxide-containing gas (at the interface between the liquid phase and the gas phase) in an environment where the pressure of the gas phase is greater than atmospheric pressure (for example, a pressure difference of 0.02 MPa or more), thereby enabling the cement slurry to efficiently absorb and fix a larger amount of carbon dioxide. The carbonation tank is usually a sealed container having a structure capable of being pressurized. By supplying carbon dioxide gas to the gas phase in the carbonation tank under pressure (an environment in which the internal pressure of the carbonation tank is made higher than atmospheric pressure), the amount of carbon dioxide immobilized in the carbonated cement slurry can be increased, and a carbonated cement slurry in which a larger amount of carbon dioxide is immobilized can be obtained. In addition, from the viewpoint of efficiently absorbing and fixing a larger amount of carbon dioxide in the cement slurry, a stirring means such as a stirring blade may be provided in the carbonation tank, and the cement slurry may be contacted with the carbon dioxide-containing gas while stirring the cement slurry using the stirring means or while circulating the cement slurry using a circulation means.

[0014] A cement slurry is a mixture (slurry) that contains cement and water. The cement is not particularly limited, and examples thereof include various Portland cements such as ordinary Portland cement, high-early-strength Portland cement, moderate-heat Portland cement, and low-heat Portland cement, mixed cements such as blast-furnace cement and fly ash cement, and ecocement, etc. These may be used alone or in combination of two or more. The water is not particularly limited, and examples thereof include tap water, industrial water, and recovered water such as supernatant water and sludge water generated in concrete manufacturing plants.

[0015] The water-cement ratio of the cement slurry (mass ratio of water to cement (water / cement)) varies depending on the application of the carbonated cement slurry and the target concentration of the carbonated cement slurry, but is preferably 0.2 to 10.0, more preferably 0.4 to 9.5, even more preferably more than 0.6 and not more than 9.0, even more preferably 1.0 to 8.5, even more preferably 2.0 to 8.0, and particularly preferably 3.0 to 7.5. If the water-cement ratio is 0.2 or more, the viscosity of the cement slurry is reduced, improving workability and enabling the cement slurry to continuously and stably absorb and immobilize carbon dioxide. If the water-cement ratio is 10.0 or less, the use of the carbonated cement slurry is not easily limited, and when the carbonated cement slurry is mixed as a part of a material such as concrete, it becomes easier to adjust the amount of other materials (e.g., water). Also, it is possible to prevent the device from becoming excessively large.

[0016] The carbon dioxide-containing gas may be a gas consisting of only carbon dioxide (carbonic acid gas), but from the standpoint of ease of availability, it may also be a gas containing carbon dioxide (carbonic acid gas) and other gases (e.g., nitrogen). The ratio of carbon dioxide (carbon dioxide gas) in the carbon dioxide-containing gas is preferably 5% by volume or more, more preferably 10% by volume or more, even more preferably 20% by volume or more, even more preferably 50% by volume or more, even more preferably 80% by volume or more, and particularly preferably 90% by volume or more. If the ratio is 5% by volume or more, the amount of carbon dioxide fixed in the cement slurry can be increased. In addition, the time required to prepare the carbonated cement slurry can be shortened. Examples of carbon dioxide-containing gases include liquefied carbon dioxide, exhaust gas generated in the cement manufacturing process (carbon dioxide concentration: approximately 20% by volume), exhaust gas generated in the steelmaking process (carbon dioxide concentration: approximately 20% by volume), exhaust gas generated in the thermal power generation process (carbon dioxide concentration: approximately 10% by volume), and gas separated and recovered from these exhaust gases (carbon dioxide concentration: approximately 100% by volume).

[0017] The carbon dioxide-containing gas is supplied from the carbon dioxide-containing gas supply device through the carbon dioxide-containing gas inflow passage to the carbon dioxide-containing gas inflow port of the carbonation device at a pressure greater than atmospheric pressure into the carbonation device. The carbon dioxide-containing gas is supplied to a gas phase of the carbon dioxide-containing gas formed above the liquid phase of the cement slurry. In addition, the inlet of the carbon dioxide-containing gas is usually disposed at a position not in contact with the cement slurry (a position vertically above the liquid level of the cement slurry, such as the upper part (e.g., the lid) of the carbonation tank) from the viewpoint of preventing clogging due to the generation of scale. The difference between the pressure of the gas phase to which the carbon dioxide-containing gas is supplied (the pressure of the gas phase in the carbonation tank) and the atmospheric pressure is preferably 0.02 to 0.2 MPa, more preferably 0.03 to 0.18 MPa, and particularly preferably 0.04 to 0.15 MPa. If the pressure is 0.02 MPa or more, the amount of carbon dioxide fixed in the cement slurry per unit time can be increased, and the cement slurry can be carbonated more efficiently. In addition, the carbonation device can be made smaller. If the pressure is 0.2 MPa or less, excessive equipment costs can be prevented.

[0018] A specific description will be given below with reference to Figures 1 to 3. In the following description, the term "upstream side" means the side close to the place where cement and water are mixed, and the term "downstream side" means the side far from the place where cement and water are mixed. FIG. 1 is a diagram showing a schematic diagram of a carbonated cement slurry production system 1 including a carbonator 2 and a mixing tank 7. The carbon dioxide-containing gas is supplied from the carbon dioxide-containing gas supply device 3 through the carbon dioxide-containing gas inlet 6 (inlet passage) to the gas phase consisting of the carbon dioxide-containing gas located above the cement slurry 15 contained in the carbonation tank 4.

[0019] A mixing tank 7 is disposed upstream of the carbonator 2 for mixing cement and water to obtain cement slurry. Cement, which is an ingredient of the cement slurry, is charged into the mixing tank 7 through the cement inlet 13 (inlet passage). Water, which is an ingredient of the cement slurry, is charged into the mixing tank 7 through the water inlet 12 (inlet passage). The cement and water charged into the mixing tank 7 are stirred and mixed using a mixing means (not shown) such as a stirring blade or a hand mixer arranged in the mixing tank 7 to prepare a cement slurry. The cement slurry prepared in the mixing tank 7 is supplied to the carbonation tank 4 through the cement slurry inlet 8 (inlet passage). A supplying means such as a pump may be provided at the cement slurry inlet 8 (inlet passage) to supply the cement slurry to the carbonation tank 4 (not shown).

[0020] The carbonated cement slurry production system 1 may include a slurry circulation path 5 for circulating the carbonated cement slurry between the carbonation tank 4 and the mixing tank 7. The carbonated cement slurry is circulated by repeatedly returning it from the carbonation tank 4 through the slurry circulation path 5 to the mixing tank 7, and then returning it from the mixing tank 7 to the carbonation tank 4 through the cement slurry inlet 8 (inlet path). In order to circulate the carbonated cement slurry, a circulation means such as a pump may be provided at the cement slurry inlet 8 (inlet passage) and the slurry circulation passage 5 (not shown). The cement slurry or the carbonated cement slurry is usually circulated in one direction by the circulation means such as a pump. The above circulation is usually performed until the cement slurry becomes a carbonated cement slurry in which a target amount of carbon dioxide (carbon dioxide gas) is absorbed and immobilized (a sufficient amount of carbon dioxide gas is absorbed and immobilized). By carbonating the cement slurry in the carbonation tank 4 while circulating the carbonated cement slurry between the carbonation tank 4 and the mixing tank 7, the amount of carbon dioxide fixed in the cement slurry per unit time can be increased, and the cement slurry can be carbonated more efficiently. Furthermore, when carbonating the cement slurry continuously, it is possible to easily adjust the time required for carbonation, etc. The carbonated cement slurry may be circulated without using a circulation means such as a pump. In this case, the inlet (inlet passage) of the cement slurry and the slurry circulation passage are not separately provided, and the inlet (inlet passage) of the cement slurry may also serve as the slurry circulation passage.

[0021] The carbonated cement slurry obtained in the carbonation tank 4 (carbonated cement slurry in which a target amount of carbon dioxide (carbon dioxide gas) has been absorbed and fixed) is transferred from the mixing tank 7 through the carbonated cement slurry outlet 14 (discharge path) to the solid-liquid separation means 10. In FIG. 1, the outlet 14 for the carbonated cement slurry is provided in the mixing tank 7, but the carbonated cement slurry may be discharged from an outlet (not shown) for the carbonated cement slurry provided in the carbonation tank 4. The discharged carbonated cement slurry can be used as a material for cement compositions such as concrete. The discharged carbonated cement slurry passes through a flow path 17 for discharging carbonated cement slurry, and is temporarily stored in a storage tank 9 for storing carbonated cement slurry 16. The storage tank 9 may have a stirring means (not shown) such as a stirring blade in order to prevent the carbonated cement slurry from settling.

[0022] The carbonated cement slurry production system 1 includes a solid-liquid separation means 10 for recovering a portion of the water in the carbonated cement slurry obtained by the carbonation device 2. The solid-liquid separation means 10 may be any means capable of separating a portion of the water in the carbonated cement slurry, and may be, for example, a general solid-liquid separation device such as a settling tank, a vacuum dehydrator, a pressure dehydrator, or a centrifugal dehydrator. The water-cement ratio of the carbonated cement slurry (mass ratio of water to cement (water / cement)) can be adjusted by separating a portion of the water in the carbonated cement slurry using the solid-liquid separation means 10. By adjusting the water-cement ratio, the amount of water contained in the carbonated cement slurry can be adjusted, and it becomes easier to adjust the amount of water contained in a cement composition when the carbonated cement slurry is used as a material for a cement composition such as concrete. The carbonated cement slurry production system 1 also includes a water return means 11 for using the water recovered by the solid-liquid separation means 10 as at least a part of the water for preparing the cement slurry. By using the recovered water as at least a part of the water for preparing the cement slurry, it is possible to avoid generation of wastewater or to significantly reduce the amount of wastewater. The recovered water is usually supplied to the mixing tank 7. The slurry circulation path, the storage tank, the solid-liquid separation means, and the water return means may be omitted.

[0023] FIG. 2 is a schematic diagram of a carbonated cement slurry production system 21 including a carbonator 22 and a carbon dioxide-containing gas supply device 23, but not including the mixing tank described above. The carbonator 22 has a carbon dioxide tank 24, a cement inlet 27, a water inlet 25, and a carbon dioxide-containing gas inlet 26. Cement, which is an ingredient of the cement slurry, is poured into the carbonation tank 24 through a cement inlet 27 (inlet channel). Water, which is an ingredient of the cement slurry, is poured into the carbonation tank 24 through a water inlet 25 (inlet channel). The cement and water poured into the carbonation tank 24 are stirred and mixed using a mixing means (not shown) such as an agitator blade or a hand mixer arranged in the carbonation tank 24 to prepare cement slurry 30. The carbon dioxide-containing gas supplying device 23 and the carbon dioxide-containing gas inlet 26 are similar to the carbon dioxide-containing gas supplying device 3 and the carbon dioxide-containing gas inlet 6 described above, respectively.

[0024] The carbonated cement slurry obtained in the carbonation tank 24 (carbonated cement slurry in which a target amount of carbon dioxide (carbon dioxide gas) has been absorbed and fixed) is discharged from a carbonated cement slurry discharge outlet 28 (discharge path). The carbonated cement slurry production system 21 is equipped with a slurry circulation path 29 for returning a portion of the carbonated cement slurry discharged from the carbonation tank 24 (the carbonation tank included in the carbonation device 22) to the carbonation tank 24 for circulating. Further, in order to circulate the carbonated cement slurry, a circulation means such as a circulation pump 44 is disposed in the slurry circulation path 29. The above circulation is usually performed until the cement slurry becomes a carbonated cement slurry in which a target amount of carbon dioxide (carbon dioxide gas) is absorbed and immobilized (a sufficient amount of carbon dioxide gas is absorbed and immobilized). By circulating the carbonated cement slurry by the circulation pump 44 and the slurry circulation path 29, the amount of carbon dioxide fixed in the cement slurry per unit time can be increased, and the cement slurry can be carbonated more efficiently. Furthermore, even when the cement slurry is carbonated continuously, the time required for carbonation can be easily adjusted. The slurry circulation path and the circulation pump may be omitted. The carbonated cement slurry production system 21 may include a storage tank, a solid-liquid separation means, a water return means, and the like (not shown), similarly to the above-mentioned carbonated cement slurry production system 1.

[0025] FIG. 3 is a schematic diagram of a carbonated cement slurry production system 31 including a carbonator 32, a carbon dioxide-containing gas supply device 33, a mixing tank 37, and a storage tank 39. A mixing tank 37 is provided upstream of the carbonator 32 for mixing cement and water to obtain cement slurry. Cement, which is an ingredient of the cement slurry, is charged into the mixing tank 37 through a cement inlet 42 (inlet passage). Water, which is an ingredient of the cement slurry, is charged into the mixing tank 37 through a water inlet 41 (inlet passage). The cement and water charged into the mixing tank 37 are stirred and mixed using a mixing means (not shown) such as an agitator blade or a hand mixer arranged in the mixing tank 37 to prepare a cement slurry.

[0026] A storage tank 39 for storing cement slurry is disposed downstream of the mixing tank 37 and upstream of the carbonation device 32. The cement slurry in the mixing tank 37 (hereinafter also referred to as "first cement slurry") is supplied to the storage tank 39 through an inlet 40 (inlet passage) for the first cement slurry and is stored therein. In order to supply the first cement slurry in the mixing tank 37 to the storage tank 39, a supply means such as a pump may be provided at the inlet 40 for the first cement slurry (not shown). The cement slurry in the storage tank 39 (hereinafter also referred to as "second cement slurry") passes through the second cement slurry inlet 38 (inlet passage) and is supplied as cement slurry 44 to be contained in the carbonation tank 34. In order to supply the second cement slurry in the storage tank 39 to the carbonation tank 34, a supply means such as a pump may be disposed at the second cement slurry inlet 38 (not shown). The carbonated cement slurry production system 31 includes a slurry circulation path 35 for circulating the carbonated cement slurry between the carbonation tank 34 and the storage tank 39. In addition, in order to circulate the carbonated cement slurry, a circulation means such as a pump may be provided in the slurry circulation path 35 (not shown). The carbon dioxide-containing gas supplying device 33 and the carbon dioxide-containing gas inlet 36 are similar to the carbon dioxide-containing gas supplying device 3 and the carbon dioxide-containing gas inlet 6 described above, respectively.

[0027] The carbonated cement slurry is circulated by repeatedly returning it from the carbonation tank 34 through the slurry circulation path 35 to the storage tank 39, and then from the storage tank 39 through the second cement slurry inlet 38 (inlet path) to the carbonation tank 34. In order to circulate the carbonated cement slurry, a circulation means such as a pump may be disposed at the inlet 38 (inlet passage) of the second cement slurry and the slurry circulation passage 35 (not shown). The cement slurry or the carbonated cement slurry is usually circulated in one direction by the circulation means such as a pump. The above circulation is usually performed until the cement slurry becomes a carbonated cement slurry in which a target amount of carbon dioxide (carbon dioxide gas) is absorbed and immobilized (a sufficient amount of carbon dioxide gas is absorbed and immobilized). By carbonating the cement slurry in the carbonation tank 34 while circulating the carbonated cement slurry between the carbonation tank 34 and the storage tank 39, the amount of carbon dioxide fixed in the cement slurry per unit time can be increased, and the cement slurry can be carbonated more efficiently. Furthermore, even when the cement slurry is carbonated continuously, the time required for carbonation can be easily adjusted. The carbonated cement slurry may be circulated without using a circulation means such as a pump. In this case, the inlet (inlet passage) of the cement slurry and the slurry circulation passage are not separately provided, and the inlet (inlet passage) of the cement slurry may also serve as the slurry circulation passage.

[0028] The carbonated cement slurry that has been carbonated in the carbonation tank 34 is discharged from the storage tank 39 through a carbonated cement slurry discharge port 43 (discharge path). In FIG. 3, the outlet 43 for the carbonated cement slurry is provided in the storage tank 39, but it is also possible to provide an outlet (not shown) for the carbonated cement slurry in the carbonation tank 34 and discharge the carbonated cement slurry from the outlet. The discharged carbonated cement slurry can be used as a material for cement compositions such as concrete. The slurry circulation path may be omitted. The carbonated cement slurry production system 31 may include a storage tank, a solid-liquid separation means, a water return means, and the like (not shown), similarly to the above-mentioned carbonated cement slurry production system 1.

[0029] The carbonated cement slurry production system may include a liquid temperature adjusting means (not shown) for adjusting the liquid temperature of at least one of the cement slurry and the carbonated cement slurry. The degree of absorption and fixation of carbon dioxide in the cement slurry and the quality of the carbonated cement slurry are affected by the temperatures of the cement slurry and the carbonated cement slurry. By adjusting the liquid temperature of at least one of the cement slurry and the carbonated cement slurry, it is possible to more efficiently absorb and fix a larger amount of carbon dioxide in the cement slurry and to control (adjust) the quality of the carbonated cement slurry. The liquid temperature adjusting means is not particularly limited as long as it has a cooling means and a heating means. The liquid temperature adjusting means can be disposed in a mixing tank, a storage tank, a carbonation tank, a slurry circulation path, etc. The liquid temperature adjusting means adjusts the liquid temperature of the cement slurry or the carbonated cement slurry based on the liquid temperature measured by a temperature measuring means (not shown) for measuring the liquid temperature of the cement slurry or the carbonated cement slurry. The temperature measuring means can be disposed in a mixing tank, a storage tank, a carbonation tank, a slurry circulation path, etc. The liquid temperature of the cement slurry or carbonated cement slurry adjusted by the liquid temperature adjusting means is preferably 10 to 50° C., more preferably 20 to 40° C. If the liquid temperature is 10° C. or higher, it is possible to prevent the cost of cooling equipment from becoming excessive. If the liquid temperature is 50° C. or lower, it is possible to more efficiently absorb and immobilize a larger amount of carbon dioxide in the cement slurry.

[0030] The carbonated cement slurry production system may include a pH measuring means (not shown) for measuring the pH of at least one of the cement slurry and the carbonated cement slurry. Based on the measured pH value of the cement slurry or the carbonated cement slurry, it is possible to determine whether or not a carbonated cement slurry in which a target amount of carbon dioxide (carbon dioxide gas) has been absorbed and immobilized has been obtained (whether or not a sufficient amount of carbon dioxide gas has been absorbed and immobilized in the cement slurry). For example, if the measured pH value of the carbonated cement slurry in the carbonation tank is within a predetermined numerical range, it may be determined that a sufficient amount of carbon dioxide gas has been absorbed and fixed in the cement slurry, and the carbonated cement slurry in the carbonation tank may be discharged as carbonated cement slurry in which a target amount of carbon dioxide (carbon dioxide gas) has been absorbed and fixed. In addition, the preparation of the carbonated cement slurry can be controlled (adjusted) by adjusting the supply of carbon dioxide-containing gas and the circulation of the cement slurry based on the measured pH value of the cement slurry or the carbonated cement slurry. The pH measuring means can be disposed in a member in which the cement slurry or the carbonated cement slurry is stored or transported, such as a mixing tank, a storage tank, a carbonation tank, or a slurry circulation path. Furthermore, each component constituting the above-mentioned carbonated cement slurry production system may be provided with various measuring means such as a thermometer for measuring the temperature of the gas phase in the carbonation tank, a carbonate ion concentration measuring device, an oxygen concentration measuring device, a carbon dioxide concentration measuring device, and a pressure gauge, for the purpose of managing the preparation of the carbonated cement slurry.

[0031] An example of a method for producing a carbonated cement slurry by carbonating a cement slurry containing cement and water with a carbon dioxide-containing gas using the above-mentioned carbonated cement slurry production system includes a cement slurry preparation step of mixing cement and water to obtain a cement slurry, a cement slurry storage step of storing the cement slurry and the carbon dioxide-containing gas in a carbonation tank so that a gas phase consisting of the carbon dioxide-containing gas is located above a liquid phase consisting of the cement slurry, and a carbonated cement slurry preparation step of supplying the carbon dioxide-containing gas to the gas phase at a pressure greater than atmospheric pressure to bring the liquid phase and the gas phase into contact with each other, thereby carbonate the cement slurry and obtain a carbonated cement slurry. [Explanation of symbols]

[0032] 1, 21, 31 Carbonated cement slurry production system 2, 22, 32 Carbonation equipment 3, 23, 33 Carbon dioxide-containing gas supply device 4, 24, 34 Carbonation tank 5, 29, 35 Slurry circulation path 6, 26, 36 Carbon dioxide-containing gas inlet 7, 37 Mixing tank 8 Cement slurry inlet 9. Storage Tank 10 Solid-liquid separation means 11 Water return means 12, 25, 41 Water inlet 13, 27, 42 Cement inlet 39 Storage Tank 14, 28, 43 Carbonated cement slurry outlet 15, 30, 44 Cement slurry 16 Carbonated cement slurry 17 Flow Path 38 Second cement slurry inlet 40 First cement slurry inlet 44 Circulation Pump

Claims

1. A carbonated cement slurry production system for producing a carbonated cement slurry by carbonating a cement slurry containing cement and water with a carbon dioxide-containing gas, comprising: The carbonated cement slurry production system includes a carbonation device for contacting the cement slurry with the carbon dioxide-containing gas, a carbon dioxide-containing gas supply device for supplying the carbon dioxide-containing gas to the carbonation device at a pressure higher than atmospheric pressure, and a mixing tank disposed upstream of the carbonation device for mixing the cement and the water to obtain the cement slurry, the carbonation device is a sealed container having a structure capable of being pressurized, has an inlet for the cement slurry and an inlet for the carbon dioxide-containing gas, and includes a carbonation tank for storing the cement slurry and the carbon dioxide-containing gas such that a gas phase of the carbon dioxide-containing gas is located above a liquid phase of the cement slurry; A system for producing carbonated cement slurry, wherein the cement slurry inlet is for supplying the cement slurry in the mixing tank to the carbonation tank.

2. A carbonated cement slurry manufacturing system as described in claim 1, comprising a cement inlet for introducing the cement into the mixing tank, and a water inlet for introducing the water into the mixing tank.

3. 2. The system for producing a carbonated cement slurry according to claim 1, further comprising a slurry circuit for circulating the carbonated cement slurry between the carbonator and the mixing tank.

4. 2. The carbonated cement slurry production system according to claim 1, further comprising a storage tank for storing the cement slurry downstream of the mixing tank and upstream of the carbonation device, and a slurry circulation path for circulating the carbonated cement slurry between the carbonation device and the storage tank.

5. The carbonated cement slurry producing system according to any one of claims 1 to 4, further comprising a storage tank for storing the carbonated cement slurry obtained by the carbonation device.

6. The carbonated cement slurry production system according to any one of claims 1 to 4, further comprising a solid-liquid separation means for recovering a part of the water in the carbonated cement slurry obtained by the carbonation device.

7. The carbonated cement slurry production system according to claim 6, further comprising a water return means for using the water recovered by the solid-liquid separation means as part of the water for preparing the cement slurry.

8. The carbonated cement slurry production system according to any one of claims 1 to 4, further comprising a liquid temperature adjusting means for adjusting the liquid temperature of at least one of the cement slurry and the carbonated cement slurry.

9. The carbonated cement slurry production system according to any one of claims 1 to 4, further comprising a pH measuring means for measuring a pH of at least one of the cement slurry and the carbonated cement slurry.

10. A method for producing a carbonated cement slurry by carbonating a cement slurry containing cement and water with a carbon dioxide-containing gas, using the carbonated cement slurry production system according to any one of claims 1 to 4, comprising: a cement slurry preparation step of mixing the cement and the water in the mixing tank to obtain the cement slurry; a cement slurry containing step of supplying the cement slurry from the mixing tank through an inlet of the cement slurry to the carbonation tank, and containing the cement slurry and the carbon dioxide-containing gas in the carbonation tank such that a gas phase of the carbon dioxide-containing gas is located above a liquid phase of the cement slurry; a carbonated cement slurry preparation step of supplying the carbon dioxide-containing gas to the gas phase at a pressure higher than atmospheric pressure to bring the liquid phase into contact with the gas phase, thereby carbonate the cement slurry to obtain a carbonated cement slurry; A method for producing a carbonated cement slurry comprising the steps of:

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