JP7634439B2 - Cement composition manufacturing system - Google Patents

Description

The present invention relates to a cement composition manufacturing system.

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 ready-mixed concrete that can obtain a concrete structure with high strength and high stability by using an aqueous medium into which a gas containing carbon dioxide is injected, Patent Document 2 describes a method for producing ready-mixed concrete that includes a stirring and injection step of obtaining an aqueous medium by injecting a gas containing carbon dioxide while stirring concrete recovery water, and a mixing step of mixing cement, coal ash, slag powder, and the aqueous medium, characterized in that the stirring and injection step is performed such that the concentration of dissolved calcium ions is 700 to 1,000 ppm.

JP 2020-37493 A Patent No. 6371127

The object of the present invention is to provide a cement composition manufacturing system capable of immobilizing carbon dioxide in a cement composition such as concrete during the manufacture of the cement composition.

As a result of intensive research into solving the above-mentioned problems, the present inventors have found that the above-mentioned objects can be achieved by a cement composition production system including a cement slurry preparation apparatus for mixing a part of the cement with water by stirring and supplying carbon dioxide gas to obtain a carbonated cement slurry in which the carbon dioxide gas has been absorbed and fixed, and a cement composition preparation apparatus for kneading the remainder of the cement with the carbonated cement slurry by stirring to obtain a cement composition, the apparatus being either (a) an apparatus having a stirring tank for stirring and mixing a part of the cement with water to obtain a mixture, and an aeration means for supplying carbon dioxide gas that is disposed in a space for accommodating the mixture in the stirring tank, or (b) an apparatus having a stirring tank for stirring and mixing a part of the cement with water to obtain a mixture, and a carbon dioxide gas supplying means for supplying carbon dioxide gas to the mixture supplied from the stirring tank, and have completed the present invention.
That is, the present invention provides the following [1] to [3].

[1] A cement composition production system for producing a cement composition containing cement and water, the cement composition production system including: a cement slurry preparation device for mixing a part of the cement with the water by stirring and supplying carbon dioxide gas to obtain a carbonated cement slurry in which the carbon dioxide gas has been absorbed and fixed; and a cement composition preparation device for kneading the remainder of the cement with the carbonated cement slurry obtained in the cement slurry preparation device by stirring to obtain the cement composition, the cement slurry preparation device being (a) a device equipped with a stirring tank for stirring and mixing the part of the cement with the water to obtain a mixture, and an aeration means for supplying the carbon dioxide gas, which is disposed in a mixture storage space in the stirring tank, or (b) a stirring tank for stirring and mixing the part of the cement with the water to obtain a mixture, and an apparatus equipped with a carbon dioxide gas supplying means for supplying the carbon dioxide gas to the mixture supplied from the stirring tank.
[2] The cement composition production system according to [1], wherein the cement slurry preparation apparatus is the apparatus of (b), the carbon dioxide gas supplying means in the apparatus of (b) comprises a mixture storage tank for storing and stirring the mixture, and an aeration means for supplying the carbon dioxide gas, which is disposed in the mixture storage space in the mixture storage tank, and the apparatus of (b) comprises a first flow passage for supplying the mixture in the stirring tank to the carbon dioxide gas supplying means, a second flow passage for supplying the mixture in the carbon dioxide gas supplying means to the stirring tank, and a pump for circulating the mixture.
[3] The cement composition production system according to [1], wherein the cement slurry preparation apparatus is the apparatus of (b), and the carbon dioxide gas supplying means in the apparatus of (b) is a pipeline for circulating the mixture supplied from the stirring tank, has a carbon dioxide gas supply port for supplying the carbon dioxide gas to the mixture circulating within the pipeline, and is a pipeline having a shape capable of stirring and mixing the mixture and the carbon dioxide gas.

The cement composition production system of the present invention makes it possible to fix carbon dioxide in a cement composition such as concrete during production of the cement composition.

FIG. 1 is a diagram showing a schematic diagram of an example of a cement composition production system of the present invention, including a cement slurry preparation apparatus (a). FIG. 1 is a diagram illustrating an example of a cement composition production system of the present invention, including a cement slurry preparation apparatus (b-1). FIG. 2 is a diagram showing a schematic diagram of an example of a cement composition production system of the present invention, including a cement slurry preparation apparatus (b-2).

The cement composition production system of the present invention is a cement composition production system for producing a cement composition containing cement and water, the cement composition production system including a cement slurry preparation device for mixing a part of the cement with water by stirring and supplying carbon dioxide gas to obtain a carbonated cement slurry in which the carbon dioxide gas has been absorbed and fixed, and a cement composition preparation device for kneading the remainder of the cement with the carbonated cement slurry obtained in the cement slurry preparation device by stirring to obtain a cement composition, the cement slurry preparation device being (a) a device equipped with a stirring tank for stirring and mixing a part of the cement with water to obtain a mixture, and an aeration means for supplying carbon dioxide gas that is disposed in a space for accommodating the mixture in the stirring tank, or (b) a device equipped with a stirring tank for stirring and mixing a part of the cement with water to obtain a mixture, and a carbon dioxide gas supplying means for supplying carbon dioxide gas to the mixture supplied from the stirring tank.
The details are explained below.

The cement slurry preparation device mixes a portion of the cement with water by stirring and supplies carbon dioxide gas to obtain a carbonated cement slurry in which carbon dioxide gas (carbon dioxide in gas form) is absorbed and fixed.
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 proportion of the amount of part of the cement (cement mixed in the cement slurry preparation device) in the total amount of cement (total amount of cement contained in the cement composition) is preferably 1 to 50 mass%, more preferably 5 to 40 mass%, even more preferably 8 to 35 mass%, even more preferably 15 to 30 mass%, and particularly preferably 20 to 28 mass%. If the proportion is 1 mass% or more, a larger amount of carbon dioxide is fixed in the cement composition. If the proportion is 50 mass% or less, the strength development of the cement composition is further improved.

The water is not particularly limited, and examples thereof include tap water and recovered water such as supernatant water and sludge water generated in concrete manufacturing plants.
The amount of water to be mixed is not particularly limited, and may be a general amount for concrete, etc. For example, the mass ratio of water to the total amount of cement (total amount of cement contained in the cement composition) [water/(total amount of cement)] is preferably 0.2 to 0.6.

Carbon dioxide gas may be supplied to the mixture (cement slurry) as a gas consisting of only carbon dioxide gas, but from the standpoint of ease of availability, etc., it may be supplied to the mixture as a gas containing carbon dioxide gas.
The ratio of carbon dioxide gas in the gas containing carbon dioxide 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 composition can be increased. In addition, the time required for supplying carbon dioxide gas can be shortened.
Examples of gases containing carbon dioxide include exhaust gas generated in a cement manufacturing process (carbon dioxide concentration: approximately 20% by volume), exhaust gas generated in a steelmaking process (carbon dioxide concentration: approximately 20% by volume), exhaust gas generated in a 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).

The cement composition production system will be described in detail below with reference to FIGS.
The cement composition producing systems 1, 11, and 31 include cement slurry preparing apparatuses 2, 12, and 32 and cement composition preparing apparatuses 9, 24, and 40.
The cement slurry preparation device is either (a) or (b) below.
[Cement slurry preparation apparatus (a)]
The cement slurry preparation apparatus (a: 2 in FIG. 1) is equipped with an agitation tank 3 for agitating and mixing a portion of cement with water to obtain a mixture, and an aeration means 4 for supplying carbon dioxide gas, which is disposed in the mixture storage space in the agitation tank 3.
Examples of the stirring and mixing means for stirring and mixing a portion of the cement with the water include a stirring blade disposed in the mixture storage space in the stirring tank 3, a hand mixer, and the like.
An example of the aeration means 4 for supplying carbon dioxide gas is a plate-type or cylindrical membrane-type aeration device.
The carbonated cement slurry obtained in the cement slurry preparation apparatus 2 is supplied to a cement composition preparation apparatus 9 through a carbonated cement slurry supply passage 7 using, for example, a pump 8 .

[Cement slurry preparation apparatus (b)]
The cement slurry preparation apparatus (b: 12 in FIG. 2 or 32 in FIG. 3) includes a stirring tank 13, 33 for stirring and mixing a portion of cement with water to obtain a mixture, and a carbon dioxide gas supplying means 14, 37 for supplying carbon dioxide gas to the mixture supplied from the stirring tank 13, 33.
Examples of the cement slurry preparation apparatus 12, 32 include the following (b-1) and (b-2).

(b-1) The cement slurry preparation apparatus (b-1: 12 in FIG. 2) includes a stirring tank 13, a carbon dioxide gas supplying means 14, a first flow passage 17 for supplying a mixture in the stirring tank 13 (prepared by mixing a part of cement with water) to the carbon dioxide gas supplying means 14, a second flow passage 18 for supplying the mixture in the carbon dioxide gas supplying means 14 to the stirring tank 13, and a pump 19 for circulating the mixture.
The carbon dioxide gas supplying means 14 includes a mixture storage tank 15 for storing and stirring the above mixture, and an aeration means 16 for supplying carbon dioxide gas, which is disposed within the mixture storage space in the mixture storage tank 15.
In the stirring tank 13, as an example of the stirring and mixing means for stirring and mixing a part of the cement with the water, the same means as in the cement slurry preparation apparatus (a) can be used.
The mixture in the stirring tank 13 is transferred to the mixture storage tank 15 through a first flow passage 17. In the mixture storage tank 15, carbon dioxide gas is supplied to the mixture from an aeration means 16 while the mixture is being stirred. After the supply of carbon dioxide gas, the mixture is transferred to the stirring tank 13 through a second flow passage 18.
As the air diffusing means 16, the same air diffusing means as that of the cement slurry preparation apparatus (a) can be used.

The mixture to which carbon dioxide gas has been supplied in the mixture storage tank 15 may be used as a carbonated cement slurry directly to be supplied to the cement composition preparation apparatus 24. Alternatively, as shown in FIG. 2 , a second flow passage 18 may be provided and the mixture may be repeatedly circulated using a pump 19 or the like through the stirring tank 13, the first flow passage 17, the mixture storage tank 15, and the second flow passage 18 in this order until a sufficient amount of carbon dioxide gas has been absorbed and fixed to form a carbonated cement slurry. The circulated mixture stored in the stirring tank 13 may then be used as a carbonated cement slurry to be supplied to the cement composition preparation apparatus 24.
The carbonated cement slurry obtained in the cement slurry preparation apparatus 12 is supplied to the cement composition preparation apparatus 24 through a carbonated cement slurry supply passage 22 using, for example, a pump 23 .

(b-2) The cement slurry preparation apparatus (b-2: 32 in FIG. 3) is a pipe for circulating a mixture supplied from a mixing tank 33 in which a carbon dioxide gas supplying means 37 in the cement slurry preparation apparatus 32 stirs and mixes a part of cement with water to obtain a mixture. The pipe has a carbon dioxide gas supply port for supplying carbon dioxide gas to the mixture circulating in the pipe, and has a form capable of stirring and mixing the mixture and carbon dioxide gas. The mixture is supplied to the pipe from the mixing tank 33 using a pump 34 or the like.
Specific examples of the pipeline include one in which a diffuser means for supplying carbon dioxide (e.g., a diffuser plate, not shown) and agitator means (e.g., a line mixer or static mixer, not shown) are arranged within the pipeline.
The mixture to which carbon dioxide gas has been supplied in the pipeline may be used as it is as a carbonated cement slurry to be supplied to the cement composition preparation apparatus 40, or the mixture may be repeatedly circulated using a pump 34 or the like through the stirring tank 33 and then through the pipeline until a sufficient amount of carbon dioxide gas has been absorbed and fixed to form a carbonated cement slurry, and then the mixture may be used as a carbonated cement slurry to be supplied to the cement composition preparation apparatus 40.
The carbonated cement slurry obtained in the cement slurry preparation apparatus 32 is supplied to the cement composition preparation apparatus 40 through a carbonated cement slurry supply passage 38 using, for example, a pump 39 .

The carbonated cement slurry obtained in the cement slurry preparation apparatus (a) or (b) may be temporarily stored in a storage tank (not shown) for storing carbonated cement slurry that is different from the cement composition preparation apparatuses (a) and (b), and the carbonated cement slurry may be supplied from the storage tank to the cement composition preparation apparatuses 9, 24, and 40 as appropriate.

In the cement slurry preparation apparatuses (a) and (b), carbon dioxide gas may be supplied from carbon dioxide gas storage devices 5, 20, and 35. Carbon dioxide gas passes through carbon dioxide gas supply passages 6, 21, and 36 from the carbon dioxide gas storage devices 5, 20, and 35, and is supplied from the air diffusion means 4, 16, etc.
Examples of the carbon dioxide gas storage devices 5, 20, and 35 include a container with a siphon tube, a cryogenic container (LGC), a storage tank, etc., which contain carbon dioxide gas liquefied by pressure. The liquefied carbon dioxide gas is usually supplied after being converted into a gaseous state through a vaporizer.
In addition, a carbon dioxide gas storage facility installed for a pH treatment device using carbon dioxide (carbon dioxide gas), which is a wastewater treatment facility in a concrete manufacturing factory, may be used as the carbon dioxide gas storage devices 5, 20, and 35.

In the cement slurry preparation devices (a) and (b), a part of the cement, water, and optionally mixed aggregate (described later) are, for example, weighed and charged into the mixing tanks 3, 13, and 33 from a material charging means (not shown) for charging the weighed materials into the mixing tank. As the material charging means, a device used in an existing concrete manufacturing plant can be used.
Furthermore, the stirring tanks 3, 13, and 33 may be provided with an auxiliary agent supplying means (not shown) for supplying an auxiliary agent to the stirring tank for the purpose of improving the properties of the cement slurry.
Here, examples of the auxiliary agent include cement admixtures, pH adjusters, etc. Examples of the cement admixture include cement dispersants such as water reducing agents, air-entraining water reducing agents, high-performance water reducing agents and high-performance air-entraining water reducing agents, and air-entraining agents, etc. These may be used alone or in combination of two or more.

In addition, the cement slurry preparation apparatuses (a) and (b) are preferably sealed containers having a structure capable of being pressurized. By supplying carbon dioxide gas under pressure (for example, by increasing the internal pressure of the cement slurry preparation apparatus to 1,200 hPa or more, which exceeds atmospheric pressure), the amount of carbon dioxide immobilized in the carbonated cement slurry can be increased, and a cement composition in which a larger amount of carbon dioxide is immobilized can be obtained.
In the above-mentioned cement slurry preparation apparatus (b-1), it is preferable that both the stirring tank 13 and the carbon dioxide gas supplying means 14 are the above-mentioned sealed containers.

The cement composition preparation apparatus (9 in FIG. 1, 24 in FIG. 2, 40 in FIG. 3) is used to obtain a cement composition by mixing the remaining part of the cement with the carbonated cement slurry obtained in the cement slurry preparation apparatus 2, 12, 32 through stirring.
Examples of the stirring and mixing means for stirring and mixing the remaining part of the cement with the carbonated cement slurry include stirring means 10, 25, 41 such as a stirring blade disposed in the space for accommodating the carbonated cement slurry in the cement composition preparation apparatus 9, 24, 40, a hand mixer, etc. The stirring means 10, 25, 41 may be one or more.
The cement composition preparation devices 9, 24, 40 may be any device capable of stirring and mixing the materials, and mixers and the like used in existing concrete manufacturing plants may be used.

In the present invention, the cement composition may be a paste containing no aggregate, but may also contain aggregate (mortar or concrete).
When the cement composition contains aggregate, the aggregate may be added to at least one of the cement slurry preparation apparatus and the cement composition preparation apparatus.
For example, when aggregate is charged into the cement slurry preparation apparatus 2, 12, 32, the aggregate is usually charged into the mixing tank 3, 13, 33 together with a portion of cement and water.
Furthermore, when aggregate is charged into the cement composition preparing apparatus 9, 24, 40, the aggregate is usually charged into the cement composition preparing apparatus 9, 24, 40 together with the remainder of the cement.

The aggregate may be fine aggregate alone or a combination of fine and coarse aggregates. In addition, any of natural aggregates, artificial aggregates, and recycled aggregates may be used.
The fine aggregate is not particularly limited, and examples thereof include river sand, mountain sand, land sand, sea sand, crushed sand, silica sand, slag fine aggregate, and lightweight fine aggregate, or a mixture of two or more types selected from these.
The coarse aggregate is not particularly limited, and examples thereof include river gravel, mountain gravel, land gravel, sea gravel, crushed stone, slag coarse aggregate, and lightweight coarse aggregate, or a mixture of two or more types selected from these.
The amount of aggregate to be mixed (when fine aggregate and coarse aggregate are used in combination, the amount of each to be mixed) is not particularly limited, and may be any amount generally used in mortar or concrete.

When the remainder of the cement and the carbonated cement slurry are stirred and mixed, other materials may be added as necessary. Examples of other materials that may be added as necessary include water, various admixtures such as air entraining agents, water reducing agents, air entraining water reducing agents, high performance water reducing agents, and high performance air entraining water reducing agents, as well as various admixtures such as fly ash, silica fume, and ground granulated blast furnace slag.
In the cement composition preparation apparatuses 9, 24, and 40, the amount of water additionally added when mixing the remaining cement with the carbonated cement slurry is preferably 20 mass % or less, more preferably 10 mass % or less, and particularly preferably 5 mass % or less, in terms of the total amount of water (total amount of water contained in the cement composition).

In the cement composition preparation apparatus 9, 24, 40, the remainder of the cement and other materials (e.g., aggregate, admixture, etc.) that are added as necessary may be added to the cement composition preparation apparatus 9, 24, 40, for example, from a material input means (not shown) for weighing each material and inputting the weighed material into the cement composition preparation apparatus 12. As the material input means, a device used in an existing concrete manufacturing plant can be used.

Each of the components constituting the cement composition production systems 1, 11, 31, such as the cement slurry preparation apparatuses (a) and (b), carbonated cement slurry supply paths 7, 22, 28, pumps (excluding pumps 19, 34 included in the cement slurry preparation apparatus (b)) 8, 23, 39, carbon dioxide gas storage apparatuses 5, 20, 35, carbon dioxide gas supply paths 6, 21, and a storage tank (not shown) for storing the carbonated cement slurry, and the cement composition preparation apparatuses 9, 24, 40, preferably has a cooling/heating means and is capable of temperature control.
Furthermore, each component constituting the above-mentioned cement composition manufacturing systems 1, 11, and 31 may be provided with various measuring means such as a thermometer for measuring the temperature of the mixture, a thermometer for measuring the temperature of the gas phase part of the cement slurry preparation apparatus, a pH measuring device, 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 preparing the carbonated cement slurry and managing the preparation of the cement composition.

REFERENCE SIGNS LIST 1, 11, 31 Cement composition production system 2, 12, 32 Cement slurry preparation device 3, 13, 33 Mixing tank 4, 14, 37 Carbon dioxide gas supply means 5, 20, 35 Carbon dioxide gas storage device 6, 21 Carbon dioxide gas supply path 7, 22, 38 Carbonated cement slurry supply path 8, 19, 23, 34, 39 Pump 9, 24, 40 Cement composition preparation device 10, 25, 41 Mixing means 15 Mixture storage tank 16 Aeration means 17 First flow path 18 Second flow path

Claims (3)

A method for producing a cement composition using a cement composition production system for producing a cement composition containing cement and water, comprising:
The cement composition producing system includes:
A cement slurry preparation device for mixing a part of the cement with the water by stirring and supplying carbon dioxide gas to obtain a carbonated cement slurry in which the carbon dioxide gas is absorbed and fixed;
a cement composition preparation device for mixing the remainder of the cement with the carbonated cement slurry obtained in the cement slurry preparation device by stirring to obtain the cement composition;
The cement slurry preparation apparatus comprises:
(a) An apparatus including a mixing tank for mixing a part of the cement with the water to obtain a mixture, and an aeration means for supplying the carbon dioxide gas, the aeration means being disposed in a space for accommodating the mixture in the mixing tank, or
(b) an apparatus including an agitation tank for agitating and mixing a portion of the cement with the water to obtain a mixture, and a carbon dioxide gas supplying means for supplying the carbon dioxide gas to the mixture supplied from the agitation tank ;
A method for producing a cement composition, characterized in that the proportion of the part of the cement in the total amount of the cement contained in the cement composition is 1 to 50 mass % . The cement slurry preparation apparatus is the apparatus of (b),
The carbon dioxide gas supplying means in the apparatus of (b) above is provided with a mixture storage tank for storing and stirring the mixture, and an aeration means for supplying the carbon dioxide gas, which is disposed in a mixture storage space in the mixture storage tank,
2. The method for producing a cement composition according to claim 1, wherein the device (b) comprises a first flow passage for supplying the mixture in the stirring tank to the carbon dioxide gas supply means, a second flow passage for supplying the mixture in the carbon dioxide gas supply means to the stirring tank, and a pump for circulating the mixture. The cement slurry preparation apparatus is the apparatus of (b),
2. The method for producing a cement composition according to claim 1, wherein the carbon dioxide gas supplying means in the apparatus (b) is a pipeline for circulating the mixture supplied from the stirring tank, the pipeline having a carbon dioxide gas supply port for supplying the carbon dioxide gas to the mixture circulating within the pipeline, and the pipeline having a shape capable of stirring and mixing the mixture and the carbon dioxide gas .

Images