JP2004189593A - Method of manufacturing carbonated solid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably manufacture a carbonated solid having a high strength regardless of the particle size distribution or the like of a raw material. <P>SOLUTION: The inside of a packed layer of noncarbonated Ca-containing raw material (or the carbonated solid) containing water is evacuated or the inside of the packed layer is evacuated after water is incorporated inside the packed layer to discharge a part of the water and after that, carbonation reaction is brought onto the packed layer under the presence of gaseous carbon dioxide. By the evacuation, surface sticking water on the raw material particle uniformly exists and gaps to be a flow passage of CO<SB>2</SB>are properly secured between raw material particles and by causing the carbonation reaction in the packed layer in this state, the carbonation reaction efficiently and uniformly proceeds through the whole packed layer and the carbonated solid having high strength can be obtained. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention involves contacting powdery and granular uncarbonated Ca-containing raw materials, such as CaO-containing waste material (eg, concrete waste material) and slag generated in a steelmaking process, with carbon dioxide gas, and converting calcium carbonate generated by a carbonation reaction. The present invention relates to a method for producing a solidified carbonated product as a main binder.

As one of the methods of using slag generated in the steelmaking process, slag in the form of powder is granulated and solidified using uncarbonated Ca (CaO and / or Ca (OH) ₂ ) contained therein. A method for obtaining a blocked solidified carbonate is known (for example, Patent Document 1). In this method, for example, a powdery and granular slag to which water has been added is filled in a mold, and carbon dioxide gas is blown into the slag-filled layer to cause a carbonation reaction on uncarbonated Ca contained in the slag, and the carbonation reaction is performed. The slag packed layer is consolidated using calcium carbonate generated by the carbonization reaction as a main binder to obtain a blocked carbonized solid.

JP-A-11-71160

  Such a technique for producing a solidified carbonic acid is very useful from the viewpoint of resource recycling because slag and other CaO-containing waste materials can be used as raw materials. In addition, the manufactured carbonized solids are used as alternatives to conventional concrete products for a variety of applications including civil engineering and building materials for road laying and construction, and materials for submersion underwater such as algae reefs and fish reefs. It is expected to be used for underwater marine reefs and fish reefs. Has been found to have

However, the solidified carbon dioxide produced as described above may not have sufficient strength (compressive strength) depending on the particle size distribution and components of the raw materials such as slag used. May cause problems such as cracks in the inside.
Therefore, an object of the present invention is to solve the problems of the prior art and to provide a method for producing a carbonized solidified body obtained by consolidating an uncarbonated Ca-containing raw material by a carbonation reaction. It is another object of the present invention to provide a method for producing a solidified carbonate that can stably produce a solidified carbonate having high strength.

Calcium carbonate (CaCO ₃ ) generated by a carbonation reaction by contacting a packed bed of powdery and non-carbonated Ca-containing raw material such as slag (hereinafter, “slag” will be described as an example) with carbon dioxide gas (CO ₂ ) In the case of producing a carbonated solidified product by consolidating slag as a main binder, it is considered that the reaction between uncarbonated Ca and CO ₂ in the slag proceeds through water existing around each slag particle. Have been. That is, while CO ₂ flowing between the slag particles is dissolved in water (surface-attached water) existing on the surface of the slag particles, Ca ions are eluted from the slag side, and CO ₂ and Ca ions dissolved and eluted in the water Is considered to react with (carbonation reaction) to precipitate CaCO _{3 on the} surface of the slag particles. The CaCO ₃ precipitated on the surface of the slag particles serves as a main binder for binding the slag particles, and the entire slag packed layer is solidified (carbonated and solidified).

The present inventors presuppose that carbonation solidification of the slag packed bed occurs on the basis of such a principle, whereby the supplied CO ₂ and the uncarbonated Ca in the slag are allowed to efficiently react with each other via water, Investigations were made to find a method that could produce a sufficient amount of CaCO ₃ to bind the particles together. In order to efficiently react uncarbonated Ca and CO ₂ in the slag through water, water is present on the surface of the slag particles, and a gap for passing the CO ₂ between the slag particles is appropriately secured. In other words, it is considered that it is necessary that water adhered to the surface of the slag particles be present in the slag packed layer and that no water be present in the gaps between the other slag particles.

Therefore, as a result of examining a specific method capable of causing a carbonation reaction under such a form of water, the inside of the slag packed layer containing water is once depressurized, and then the slag packed layer is formed. A method of causing a carbonation reaction in the presence of carbon dioxide, or after sufficient water is contained in the slag packed bed, and then depressurizing the inside of the slag packed bed to discharge a part of the water, and then It has been found that a method of causing a carbonation reaction in a slag packed bed in the presence of carbon dioxide is very effective. In addition, as described above, the inside of the solidified carbonate containing water is once depressurized for the solidified carbonate obtained by solidifying the slag packed layer with carbonic acid, and then the solidified carbonate is again rehydrated in the presence of carbon dioxide gas. After the carbonation reaction is caused, or after sufficient water is contained in the solidified carbonate, the inside of the solidified carbonate is decompressed and a part of the water is discharged. It has been found that by causing a carbonation reaction again in the presence of a gas, the strength of the carbonized solid can be effectively increased.

The present invention has been made based on such findings, and the features thereof are as follows.
[1] A method for producing a carbonated solidified product obtained by consolidating a powdery uncarbonated Ca-containing raw material by a carbonation reaction,
In causing the packed layer of the uncarbonated Ca-containing raw material to be solidified by the carbonation reaction, or in causing the carbonized solid obtained by solidifying the packed layer of the uncarbonated Ca-containing raw material by the carbonation reaction to cause the carbonation reaction again,
A method for producing a solidified carbonized product, comprising reducing the pressure inside the packed bed or the solidified carbonate containing moisture, and then causing a carbonation reaction in the packed bed or the solidified carbonate in the presence of carbon dioxide gas.

[2] A method for producing a carbonized solid obtained by consolidating a powdery uncarbonated Ca-containing raw material by a carbonation reaction,
In causing the packed layer of the uncarbonated Ca-containing raw material to be solidified by the carbonation reaction, or in causing the carbonized solid obtained by solidifying the packed layer of the uncarbonated Ca-containing raw material by the carbonation reaction to cause the carbonation reaction again,
After impregnating the inside of the packed bed or the solidified carbonate, water is discharged by depressurizing the inside of the packed bed or the solidified carbonate. A method for producing a solid carbonated product, wherein a carbonation reaction is caused in the presence of carbon dioxide gas.

[3] A method for producing a carbonated solidified product obtained by consolidating a powdery uncarbonated Ca-containing raw material by a carbonation reaction,
By causing a carbonation reaction in the presence of carbon dioxide in the packed bed of the non-carbonated Ca-containing raw material containing water, the packed bed is solidified into a solidified carbonate, and then water is contained in the solidified carbonate. , After which a part of the water is discharged by depressurizing the inside of the solidified carbon dioxide, and thereafter, the carbonation is caused to occur again in the presence of carbon dioxide in the solidified carbonic acid. Manufacturing method of solidified body.

[4] A method for producing a carbonated solidified product obtained by consolidating a powdery uncarbonated Ca-containing raw material by a carbonation reaction,
After water is contained inside the packed bed of the uncarbonated Ca-containing raw material, a part of the water is discharged by reducing the pressure inside the packed bed, and thereafter, the carbonation reaction is performed in the presence of carbon dioxide gas in the packed bed. Is caused to consolidate the packed bed into a carbonated solidified body, and then water is contained inside the carbonized solidified body, and then a part of the water is discharged by reducing the pressure inside the carbonized solidified body. Thereafter, a carbonation reaction is caused to occur again in the presence of carbon dioxide gas in the solidified carbonic acid product, thereby producing a solidified carbonic acid product.

[5] In the production method according to any one of the above [2] to [4], a carbonized solid obtained by solidifying a packed layer of uncarbonated Ca-containing raw material or a packed layer of uncarbonated Ca-containing raw material by a carbonation reaction. Is immersed in water so that water is contained in the filled layer or the solidified carbonate, and then the pressure in the packed layer or the solidified carbonate is reduced.
[6] In the production method according to any one of the above [2] to [4], a carbonized solid obtained by solidifying a packed layer of uncarbonated Ca-containing raw material or a packed layer of uncarbonated Ca-containing raw material by a carbonation reaction. A method for producing a solidified carbonated material, wherein water is contained in a packed bed or a solidified carbonated body by spraying water, and then the pressure inside the packed bed or the solidified carbonated body is reduced.
[7] In the production method according to any one of the above [1] to [6], a carbonized solidified body obtained by consolidating a packed layer of a carbonated Ca-containing raw material or a packed layer of an uncarbonated Ca-containing raw material by a carbonation reaction. In the step of depressurizing the inside, a method for producing a solidified carbonate is characterized in that the inside of the packed layer or the solidified carbonate is reduced to 0.8 atm or less.

  According to the above-described method of the present invention, a solidified carbonate having high strength can be stably produced regardless of the particle size distribution and components of the raw material. For this reason, it is possible to reliably prevent cracks in the solidified carbonic acid during transportation and use.

Hereinafter, the details of the method of the present invention will be described.
The present invention may be applied to the case where the packed bed of the powdery granular uncarbonated Ca-containing raw material is carbonated and solidified, or may be applied to the case where recarbonation is performed to improve the strength of the carbonized solidified body. Is also good.
In the present invention, the carbonation reaction is performed again on the carbonized solid obtained by consolidating the packed layer of the uncarbonated Ca-containing raw material by the carbonation reaction or by solidifying the packed layer of the uncarbonated Ca-containing raw material by the carbonation reaction. This is a method for producing a solidified carbonic acid product.

As described above, the powdery uncarbonated Ca-containing raw material such as slag (hereinafter, “slag” will be described as an example) is consolidated by a carbonation reaction to produce a carbonized solidified product. The reaction between the uncarbonated Ca and CO ₂ is caused by the fact that the CO ₂ flowing between the slag particles is dissolved in the water (surface-adhered water) present on the surface of the slag particles, and Ca ions are eluted from the slag side. It is considered that CaCO ₃ precipitates on the surface of the slag particles due to the reaction (carbonation reaction) between CO ₂ dissolved and eluted in water and Ca ions.

In the prior art shown in Patent Document 1, etc., carbonation treatment is performed in a state where an appropriate amount of water (for example, a water content of about 5 to 10%) is added to slag. However, since the slag and the water are simply mixed, the distribution state of the water in the slag packed bed becomes uneven. As a result, Torimichi of CO ₂ is at busy water CO ₂ does not flow sufficiently for not sufficiently secured, and therefore less likely to occur carbonation reaction, also Ca ions where the slight carbonation reaction occurs It is considered that the generated CaCO ₃ cannot contribute to the bonding between the slag particles because it is the surface portion of the dissolved water (that is, a place distant from the slag particle surface). On the other hand, CO ₂ since Torimichi of CO ₂ is sufficiently secured at less water flow, but because essential water is small, less Ca ions eluted from the slag, hardly occurs in this case also the carbonation reaction It is considered to be. Then, as a result, the obtained carbonized solid body has insufficient strength due to insufficient carbonation or has a large variation in strength.

  Therefore, in one embodiment of the production method of the present invention, the slag packed layer ("carbonated solidified body" when the carbonized solidified body is re-carbonated to improve the strength. In the following, the "slag filled layer" is taken as an example. In order to equalize the distribution of water in the slag packed layer, a process of temporarily reducing the pressure inside the slag packed bed containing water is performed. The principle that the distribution of water in the slag packed layer is considered to be uniform by performing such a decompression process will be described with reference to FIG. 1 (schematic diagram).

FIG. 1 (a) shows a slag packed bed containing an appropriate amount of water (usually, an amount necessary or sufficient for the carbonation treatment or an amount close thereto) (for example, a slag mixed by adding water to a mold). 2 shows the inside of a slag-filled layer that is configured by being charged. In this state, the gap portion of the slag particles varies in the presence state of water due to the influence of the size of the gap, surface tension, and the like, and the portion where a large amount of water exists so as to block the passage of CO ₂ and the carbonation There is a portion where the amount of water (water attached to the surface of the slag particles) necessary for the reaction is not sufficiently present. When the pressure inside the slag packed layer is reduced in this state, the partially unevenly distributed water is drawn and moves, and adheres to the surface of the slag particles having a small amount of water adhering to the surface. As a result, presence state of water in the gap portion of the slag particles are uniform, as in FIG. 1 as shown in (b), CO ₂ between each slug particle surfaces deposited water is uniformly present in and slag particles A state in which a gap serving as a path is appropriately secured is realized in the entire slag filling layer. In addition, a part of the water present in the slag packed bed may be discharged to the outside of the packed bed due to the reduced pressure.

Then, by causing a carbonation reaction in the presence of carbon dioxide in the slag packed layer in which the distribution state of water (pore water) is optimized by the decompression treatment as described above, the entire slag packed bed is efficiently and uniformly formed. The carbonation reaction proceeds, and as a result, the bonding force between the slag particles by the generated CaCO ₃ is greatly improved, and a carbonized solid having high strength can be stably obtained. Here, the gas actually used to cause the carbonation reaction in the presence of carbon dioxide is carbon dioxide or a carbon dioxide-containing gas.

Further, in order to improve the strength of solidification of carbonic acid in which the slag packed layer is solidified by the carbonation reaction, the principle of causing a carbonation reaction (recarbonation) again in the carbonized solid is the same as above.
In this case, the target of recarbonation is a solid carbonate obtained by a conventional method or the above-described method. A carbonized solid obtained by consolidating a packed bed of powdered and granular non-carbonated Ca-containing raw material such as slag by a carbonation reaction has fine through-holes throughout, and allows water to be contained (permeated) therein. )be able to. The carbonized solid is subjected to recarbonation for the purpose of improving the strength. At this time, in order to make the distribution of water in the carbonized solid uniform, a process of reducing the pressure inside the carbonized solid is performed. I do.

In this case, the principle that the distribution state of water in the solidified carbon dioxide is considered to be uniform is the same as that of the slag packed layer described above. That is, assuming that FIG. 1 (a) shows the inside of a carbonated solid containing an appropriate amount of water (usually an amount of water necessary and sufficient for the carbonation treatment or an amount close thereto), slag particles in this state In the gap portion of, there is a variation in the presence state of water due to the influence of the size of the gap, surface tension, etc., and the portion where a large amount of water exists so as to block the CO ₂ passage and the amount of water necessary for the carbonation reaction There is a portion where water (water adhering to the surface of slag particles) does not sufficiently exist. Then, when the inside of the solidified carbonate is decompressed in this state, the partially unevenly distributed water is drawn and moves, and adheres to the surface of the slag particles having a small amount of water adhering to the surface. As a result, presence state of water in the gap portion of the slag particles are uniform, as in FIG. 1 as shown in (b), CO ₂ between each slug particle surfaces deposited water is uniformly present in and slag particles A state in which a gap serving as a path is appropriately secured is realized in the entire carbonated solidified body. It should be noted that a part of the water present in the solidified carbon dioxide may be discharged to the outside due to the reduced pressure.

Then, a carbonation reaction is caused to occur again in the presence of carbon dioxide in the carbonized solid in which the distribution state of water (pore water) has been optimized by the reduced pressure treatment as described above, so that the entire carbonized solid is efficiently and uniformly formed. The carbonation reaction proceeds during the reaction, and as a result, the bonding force between the slag particles is greatly improved by newly generated CaCO ₃ , and the strength of the carbonized solid can be significantly increased. Here, the solidified carbonate to be recarbonated is already solidified by CaCO ₃ generated by the carbonation reaction, but the slag contains a considerable amount of uncarbonated Ca, and Since the entire surface of each slag particle is not covered with the precipitated CaCO ₃ , Ca ions are eluted from the slag particle to the surface adhering water even during the recarbonation, and the carbonation reaction proceeds. Become.

  In the present invention, in solidifying the slag packed bed with carbonic acid, the distribution of water (pore water) in the slag packed bed is made uniform by the above-described reduced pressure treatment, and then carbonation is performed. The solidified product is further recarbonated, and also at this time, the distribution of water (interstitial water) in the carbonized solidified product is made uniform by the above-described reduced pressure treatment, and then recarbonation can be performed. That is, in this production method, after the inside of the slag packed layer containing water is subjected to a reduced pressure treatment, the slag packed bed is consolidated by causing a carbonation reaction in the presence of carbon dioxide gas in the slag packed bed. If necessary, water (water required for the carbonation reaction) is included in the interior of the solidified carbon dioxide obtained in the above, and then the inside of the solidified carbonic acid is subjected to a reduced pressure treatment. This causes a carbonation reaction again, whereby a solidified carbonate having particularly high strength can be obtained.

Next, another embodiment of the manufacturing method of the present invention will be described.
In this embodiment, water in the slag packed layer ("carbonated solidified body" in the case where carbonized solidified body is recarbonated to improve the strength, and "slag packed bed" will be described below as an example). In order to make the distribution state of the slag packed layer uniform, sufficient water is contained inside the slag packed bed, and then the inside of the slag packed bed is decompressed and a part of the water (that is, extra Water). The principle that the distribution state of water in the slag packed layer is considered to be uniform by performing such processing will be described with reference to FIG. 2 (schematic diagram).

FIG. 2A shows a state in which water is sufficiently contained inside the slag packed layer. In this state, water exists in many gaps between the slag particles, and bubbles exist in the gap water. These bubbles are bubbles trapped in the slag packed bed when water is contained in the slag packed bed, and such bubbles are widely present throughout the slag packed bed. When the pressure inside the slag packed bed is reduced in this state, the bubbles in the pore water greatly expand as shown in FIG. 2 (b), and the bubbles push the pore water out of the slag packed bed, and finally, as shown in FIG. As shown in (c), most of the interstitial water flows out of the slag packed layer, leaving water attached to the surface of the slag particles (surface attached water). That is, most of the pore water not only unnecessary for the carbonation reaction but also obstructing the passage of CO _{2 in} the slag packed bed is removed from the inside of the slag packed bed. As a result, a state in which the water adhering to the surface is uniformly present in each slag particle, and a gap between the slag particles as a passage for CO ₂ is appropriately secured is realized in the entire slag packed layer.

Then, by causing a carbonation reaction in the presence of carbon dioxide gas in the slag packed layer in which the distribution state of water (pore water) has been optimized by the above treatment, the entire slag packed bed is efficiently and uniformly carbonated. The formation reaction proceeds, and as a result, the bonding force between the slag particles by the generated CaCO ₃ is greatly improved, and a solidified carbonate having high strength can be stably obtained. Here, the gas actually used to cause the carbonation reaction in the presence of carbon dioxide is carbon dioxide or a carbon dioxide-containing gas.

Further, in order to improve the strength of solidification of carbonic acid in which the slag packed layer is solidified by the carbonation reaction, the principle of causing a carbonation reaction (recarbonation) again in the carbonized solid is the same as above.
In this case, the target of recarbonation is a solid carbonate obtained by a conventional method or the above-described method. A carbonized solid obtained by consolidating a packed bed of powdered and granular non-carbonated Ca-containing raw material such as slag by a carbonation reaction has fine through-holes throughout, and allows water to be contained (permeated) therein. )be able to. This carbonized solid is subjected to recarbonation for the purpose of improving the strength. At this time, in order to make the distribution of water in the carbonized solid uniform, sufficient water is supplied inside the carbonized solid. After that, the inside of the solidified carbonic acid body is depressurized, and a process of discharging a part of the water (ie, extra water other than the water attached to the surface of the slag particles) is performed.

In this case, the principle that the distribution state of water in the solidified carbon dioxide is considered to be uniform is the same as that of the slag packed layer described above. That is, assuming that FIG. 2 (a) shows a state in which water is sufficiently contained in the solidified carbonate, in this state, water exists in many gaps of the slag particles and bubbles exist in the pore water. are doing. When the inside of the carbonated solid is depressurized in this state, the bubbles in the pore water greatly expand as shown in FIG. 2B, and the bubbles push the pore water to the outside of the carbonated solid. As shown in (c), most of the interstitial water flows out of the solidified carbonic acid, leaving the water attached to the surface of the slag particles (water attached to the surface). That is, not only is not necessary for the carbonation reaction, but also most of the pore water that inhibits the passage of CO _{2 in} the carbonized solidified body is removed from the inside of the carbonized solidified body. As a result, a state in which the water adhering to the surface is uniformly present in each slag particle, and a gap between the slag particles as a passage for CO ₂ is appropriately secured is realized in the entire solidified carbon dioxide body.

Then, the carbonation reaction is caused to occur again in the presence of carbon dioxide in the carbonated solid in which the distribution state of water (pore water) has been optimized by the treatment as described above, so that the entire carbonated solid is efficiently and uniformly formed. The carbonation reaction proceeds, and as a result, the bonding force between the slag particles is greatly improved by newly generated CaCO ₃ , and the strength of the carbonized solid can be significantly increased. Here, the solidified carbonate to be recarbonated is already solidified by CaCO ₃ generated by the carbonation reaction, but the slag contains a considerable amount of uncarbonated Ca, and Since the entire surface of each slag particle is not covered with the precipitated CaCO ₃ , Ca ions are eluted from the slag particle to the surface adhering water even during the recarbonation, and the carbonation reaction proceeds. Become.

  Further, in the present invention, when carbonizing and solidifying the slag packed bed, the distribution of water (pore water) inside the slag packed bed is made uniform by the above-mentioned method, and then carbonation is carried out. The body is further recarbonated, and at this time, the recarbonation can be performed after the water (interstitial water) distribution of the solidified carbonate is uniformized by the method described above. That is, in this manufacturing method, after water is contained inside the slag packed layer, a part of the water (ie, extra water other than the water attached to the surface of the slag particles) is reduced by reducing the pressure inside the slag packed layer. The slag-filled layer was solidified by causing a carbonation reaction in the presence of carbon dioxide gas in the slag-filled layer, and then water was contained inside the thus obtained carbonized solidified body. Thereafter, a part of the water (ie, excess water other than the water adhering to the surface of the slag particles) is discharged by depressurizing the inside of the carbonated solid, and thereafter, the carbonated solid is again carbonated in the presence of carbon dioxide gas. This causes a reaction, whereby a solidified carbonate having particularly high strength can be obtained.

  The above-described “decompression treatment (including any of the cases of FIGS. 1 and 2) -carbonation treatment” of the raw material packed layer or the carbonated solid in the method of the present invention may be repeated plural times. In this case, for example, "decompression treatment-carbonation treatment" based on the principle of FIG. 2 may be performed first, and then "decompression treatment-carbonation treatment" based on the principle of FIG. 1 may be performed.

Next, preferable production conditions in the method of the present invention described above will be described.
A method for producing a carbonated solidified product by consolidating a powdery granular uncarbonated Ca-containing raw material by a carbonation reaction, wherein uncarbonated Ca contained in the uncarbonated Ca-containing raw material, that is, CaO and / or Ca (OH) ₂ only needs to be contained at least as a part of the composition of the solid particles. Therefore, in addition to CaO and Ca (OH) ₂ as minerals, 2CaO · SiO ₂ , 3CaO · SiO ₂ , Also included are those present in solid particles as part of the composition, such as glass.

Examples of the powdery uncarbonated Ca-containing raw material include concrete and slag generated in a steelmaking process. The type of the uncarbonated Ca-containing raw material will be described later in detail.
There is no particular limitation on the particle size of the powdery uncarbonated Ca-containing raw material, but it is preferable that the particle size is somewhat small in order to secure the contact area with CO ₂ and increase the reactivity, and specifically, (I.e., excluding solid particles having a large particle size which are inevitably contained), those having a particle size of 20 mm or less, particularly preferably 5 mm or less are preferred.

  In the method of the present invention, a method of including water in a packed bed of uncarbonated Ca-containing raw material or a carbonated solid obtained by carbonating the same is optional. Water can be contained therein by a method of immersion (in the case of a raw material packed layer, the entire packed layer holding container such as a mold is immersed in water), a method of sprinkling water on the raw material packed layer or the solidified carbon dioxide, or the like. . In addition, an uncarbonated Ca-containing raw material sufficiently containing water may be charged in a container such as a mold.

The method of depressurizing the inside of the raw material filling layer or the solidified carbon dioxide is also optional. For example, an evacuation (suction) mechanism in which a mold on which the raw material filling layer is formed can be made airtight and a vacuum pump is provided in the mold And the inside of the mold (that is, the inside of the raw material filling layer or the solidified carbon dioxide) may be depressurized by this exhaust mechanism. Alternatively, the solidified carbonic acid removed from the mold or the like may be housed in a separately prepared airtight container, and the inside of the airtight container may be depressurized by the above-described exhaust (suction) mechanism.
There is no particular limitation on the degree of decompression in the depressurization step, but in order to promptly move water inside the raw material packed layer or the carbonated solid or to quickly discharge excess water, the raw material packed layer or It is preferable to reduce the pressure inside the solidified carbon dioxide to 0.8 atm or less, more preferably 0.2 atm or less.

  The water content in the raw material packed layer or the solidified carbonated material to be carbonated varies depending on the porosity (porosity) inside the raw material packed layer or the solidified carbonic material, but is usually 1 to 7%, preferably 2 to 2%. It is appropriate to set it to about 5%. When an uncarbonated Ca-containing raw material having a particle size of substantially 3 mm or less is used, the water content is generally 3 to 11%, preferably 5 to 9%. Therefore, when a part of the water in the raw material packed bed or the solidified carbonate is discharged by the decompression treatment, the water content before the decompression treatment, the degree of decompression, so that the water content after the decompression treatment is in the above range, It is preferable to adjust the porosity (porosity) and the like inside the raw material packed layer or the solidified carbonate.

  In order to cause a carbonation reaction in the raw material packed bed or the carbonized solid in the presence of carbon dioxide gas, carbon dioxide gas or carbon dioxide-containing gas (hereinafter, simply referred to as “carbon dioxide gas”) is usually placed in the above-mentioned mold or airtight container. Supply and blow carbon dioxide gas into the raw material packed layer or the solidified carbon dioxide, or place the raw material packed layer or the solidified carbonic acid in a carbon dioxide gas atmosphere of an airtight container, and place carbon dioxide gas inside the raw material packed layer or the solidified carbonic acid. Infiltrate.

  The non-carbonated Ca-containing raw material is not particularly limited as long as it contains non-carbonated Ca as at least a part of the composition as described above. Slag and concrete (for example, waste concrete) generated in the steel manufacturing process are particularly preferable because they can be recycled. Generally, the CaO concentration of slag generated in the steel making process is about 13 to 55 mass%, and the CaO concentration of concrete (for example, waste concrete) is about 5 to 15 mass% (CaO concentration in cement: 50 to 60 mass%). In addition, since they are easily available, they can be said to be extremely suitable materials as uncarbonated Ca-containing raw materials. Therefore, it is preferred that at least a part of the uncarbonated Ca-containing raw material, and particularly preferably the main raw material is slag and / or concrete.

  Slag generated in the steelmaking process includes blast furnace slag such as blast furnace slow cooling slag and blast furnace granulated slag, decarburized slag, dephosphorized slag, desulfurized slag, Examples include, but are not limited to, steelmaking slag such as silicon slag, cast slag, ore reduction slag, electric furnace slag, and the like, and a mixture of two or more slags can also be used. .

  In addition, slag generated in the steelmaking process contains a considerable amount of iron (iron such as granular iron). If such slag is used as it is, the CaO concentration in the raw material decreases by the amount of iron. For this reason, it is preferable to use slag that has undergone ingot (iron) recovery processing. This ingot (iron) recovery processing is generally performed to recycle the iron contained in slag to the steelmaking process. Usually, the slag is pulverized to perform this ingot recovery. A considerable amount of iron contained in the slag is recovered and removed by means such as magnetic separation.

Further, as the concrete, for example, waste concrete generated by demolishing a building or civil engineering structure or the like can be used.
Examples of the non-carbonated Ca-containing material include mortar, glass, alumina cement, CaO-containing refractories, etc., in addition to the above-mentioned slag and concrete, and one or more of these materials may be used alone or in combination. And / or mixed with concrete.
These materials are optionally crushed into powders and used as raw materials.

The uncarbonated Ca-containing raw material does not need to be solid particles containing the entire amount of uncarbonated Ca. That is, if a sufficient amount of CaCO ₃ is produced as a binder for the solidified carbonate by carbonation of the uncarbonated Ca contained in the uncarbonated Ca-containing raw material, the uncarbonated Ca-containing material is added to the uncarbonated Ca-containing raw material. May be contained. Examples of such solid particles include natural stone, sand, soluble silica, fly ash, clinker ash, and metals (for example, metallic iron and iron oxide).

In addition, among these, metallic iron, iron oxide, soluble silica, etc., when the solidified carbonate produced by the method of the present invention is used as a material for submersion in water, a fixing agent for sulfur or phosphorus in water, such as seaweed. It works effectively as a nutrient source for aquatic plants. In addition to these, an arbitrary component (particle) can be contained in an appropriate amount, that is, as long as the strength of the solidified carbonate is not reduced.
Further, as a component serving as a binder, for example, a small amount of cement, finely ground granulated slag, or the like may be added.

Examples of the carbon dioxide gas or the carbon dioxide-containing gas used for causing a carbonation reaction in the raw material packed bed or the solidified carbon dioxide include, for example, a lime burning plant exhaust gas (usually CO ₂ : 25%) discharged in an integrated steel mill. Suitable examples include, but are not limited to, heating furnace exhaust gas (usually, CO ₂ : around 6.5%). In addition, if the concentration of CO ₂ in the gas is too low, there is a problem that the treatment efficiency is reduced, but other problems are not particularly significant. Thus, although the CO ₂ concentration is not particularly limited, it is preferable that the CO ₂ concentration of 3% or more to do efficient processing.

There is no particular limitation on the supply amount of carbon dioxide gas, but as a general guide, a gas supply amount of about 0.004 to 0.5 m ³ / min · t (raw material ton) may be secured. Also, there is no special restriction on the gas supply time (carbonation treatment time), but as a guide, the time when the supply amount of carbon dioxide gas becomes 3% or more of the weight of the uncarbonated Ca-containing raw material, that is, the gas amount Convert to the raw material 1t per 15 m ³ or more, preferably it is preferable to carry out the gas supply to 200 meters ³ or more carbon dioxide is supplied.

The supplied carbon dioxide gas or carbon dioxide-containing gas may be at room temperature, but if the temperature of the gas is higher than room temperature, it is advantageous because the reactivity increases accordingly. However, if the temperature of the gas is excessively high, the moisture in the raw material packed bed and the solidified carbon dioxide is dried, or CaCO ₃ is decomposed into CaO and CO _2. It is necessary to use a gas having a temperature that does not cause the gas.

Preferably, the carbon dioxide gas or the carbon dioxide-containing gas is supplied to the raw material packed bed or the solidified carbon dioxide in a humidified state in order to prevent the raw material packed bed or the solidified carbonic acid from drying. Therefore, when supplying gas to the raw material packed bed or the solidified carbon dioxide, carbon dioxide gas or a gas containing carbon dioxide is once blown into water to saturate H ₂ O, and then supplied to the raw material packed bed or the solidified carbon dioxide. It is preferable to prevent the raw material packed layer or the solidified carbonic acid from drying, thereby promoting the carbonation reaction.

Next, specific embodiments of the present invention will be described.
FIG. 3 shows an example of an implementation state of the method of the present invention, and shows a state in which a mold for forming a raw material filling layer is longitudinally sectioned.
The mold 1 is a mold that can be made substantially airtight. In this example, the mold 1 includes a container-shaped main body 100 and a lid 101 that closes an upper part of the main body 100. A gas supply / exhaust section 2 (gas supply / exhaust space) is provided at the bottom of the main body 100, and a number of gas through holes 20 are formed in a partition wall between the gas supply / exhaust section 2 and the main body 100. I have. A gas supply / exhaust pipe 3 is connected to the gas supply / exhaust section 2, and the gas supply / exhaust pipe 3 is supplied with a carbon dioxide gas or a carbon dioxide-containing gas (hereinafter collectively referred to as “carbon dioxide gas”). And a suction pipe system 5 having a suction pump 6 for reducing the pressure in the mold 1. In addition, an exhaust pipe 7 for exhausting gas supplied into the mold is connected to an upper portion of the mold 1. In addition, in the drawings, reference numerals 8 to 10 denote on-off valves provided in each piping system.

  In one embodiment of the method of the present invention in FIG. 3 (an embodiment aiming at the operation of FIG. 1), a raw material containing uncarbonated Ca in the form of powder such as slag is charged into a mold 1 and an appropriate amount of the raw material is added. The raw material packed layer A containing water (usually, an amount of water necessary and sufficient for the carbonation treatment or an amount close thereto) is formed. This water may be added to the uncarbonated Ca-containing raw material before being charged into the mold 1 or may be added to the raw material packed layer A.

After forming the raw material filling layer A as described above, the lid 101 is attached to make the mold 1 airtight. After that, the exhaust is exhausted from the inside of the mold 1 by suction using the suction pump 6 of the suction pipe system 5. Do. As a result, the pressure inside the raw material packed layer A (the mold) is reduced, and in the raw material packed layer A, an appropriate distribution state of water (pore water) as described above, that is, water adhering to the surface of each raw material particle. As a result, a state is realized in which gaps that are uniformly present and serve as a path for CO ₂ between the raw material particles are appropriately secured.

Then, the suction pipe system 5 and the gas supply pipe system 4 are switched by operating the on-off valves 8 and 9, and carbon dioxide gas is supplied from the gas supply pipe system 4 into the mold 1 for a certain period (for example, several hours to several hundred hours). Supply). After the carbon dioxide gas is introduced into the gas supply / exhaust section 2, the carbon dioxide gas is blown into the upper raw material filling layer A from the gas through hole 20. Part of the carbon dioxide gas passing through the raw material filling layer A reacts with Ca ions eluted from the raw material particles to the water adhering to the surface thereof, and CaCO ₃ precipitates on the surface of the raw material particles, and this serves as a binder to serve as a binder. A solidifies to form a carbonized solid. The remainder of the carbon dioxide gas passes through the raw material filling layer A and is discharged from the exhaust pipe 7 to the outside of the mold 1. In some cases, carbon dioxide gas may be supplied into the raw material packed bed A in a state where the on-off valve 10 of the exhaust pipe 7 is closed. It is preferable to release the gas accumulated in the frame 1 so that the concentration of carbon dioxide in the mold 1 is maintained at a predetermined level or more. Further, the gas may be released by reducing the pressure inside the mold 1, and thereafter, a predetermined concentration of carbon dioxide may be introduced. After the above-mentioned supply of carbon dioxide gas has been performed for a certain period of time, it is released from the mold and the carbonized solid is removed. Note that the above-described “decompression treatment-carbonation treatment” may be performed by repeating this plural times.

  Further, in another embodiment of the method of the present invention in FIG. 3 (an embodiment aiming at the operation of FIG. 2), first, a sufficient amount of water is contained in the raw material filling layer A formed in the mold 1. As the method, the mold 1 may be immersed in water in the water tank with the upper part of the mold 1 opened, or a sufficient amount of water may be sprinkled from the upper part of the raw material filling layer A. In addition, an uncarbonated Ca-containing raw material that has been sufficiently mixed with water may be charged into the mold 1.

After the raw material packed layer A is sufficiently filled with water as described above, the lid 101 is attached to make the mold frame 1 airtight, and then the mold is suctioned using the suction pump 6 of the suction pipe system 5. Exhaust is performed from inside the frame 1. As a result, the pressure inside the raw material filling layer A (the mold) is reduced, and the air and water (pore water) in the raw material filling layer A are extruded from the raw material filling layer, and pass through the gas through holes 20 and the gas supply / exhaust portion 2. And is discharged from the mold 1. As a result, the appropriate distribution state of water (pore water) as described above in the raw material packed layer A, that is, water adhering to the surface is uniformly present on each raw material particle, and CO ₂ is present between the raw material particles as shown in FIG. A state in which a gap that becomes a road is appropriately secured is realized.

  Then, the suction pipe system 5 and the gas supply pipe system 4 are switched by operating the on-off valves 8 and 9, and carbon dioxide gas is supplied from the gas supply pipe system 4 into the mold 1 for a certain period (for example, several hours to several hundred hours). ) To supply and perform a carbonation treatment of the raw material packed layer A. The conditions, effects, and the like of this carbonation treatment are the same as those in the above-described embodiment. After this carbonation treatment, the mold is released, and the carbonized solid is taken out. Note that the above-described “decompression treatment-carbonation treatment” may be performed by repeating this plural times.

Although the solidified carbonate having sufficient strength is manufactured by the manufacturing method of each of the embodiments as described above, in order to further increase the strength of the solidified carbonate, the solidified carbonate obtained in the above-described process is used. Recarbonation may be performed in a state of being stored in the mold 1 as it is, or transferred to another container.
At that time, in the same manner as in the case of carbonizing and solidifying the raw material packed layer A, (a) a method in which the inside of the carbonized solidified product is once depressurized, and thereafter, a carbonic acid gas is supplied to carry out recarbonation, (b) After sufficient water is contained in the carbonated solidified body, the inside of the carbonized solidified body is subjected to a reduced pressure treatment to discharge excess water, and thereafter, a method of performing carbonation gas supply and performing recarbonation. It is preferable to adopt such a method.
In the case of recarbonating the carbonized solid, similarly to the case of carbonizing the raw material-filled layer, a method of blowing carbon dioxide into the carbonized solid, and placing the carbonized solid in a carbon dioxide gas atmosphere and putting carbon dioxide inside. There is a method of infiltrating, and in the present invention, any method may be used.

  FIG. 4 shows an example of an embodiment of a method of blowing carbon dioxide gas into a carbonized solidified body in the method of the present invention, and shows a state in which a processing container is longitudinally sectioned. The apparatus configuration of the processing container is substantially the same as the embodiment of FIG. That is, the processing container 1a (this container may be a mold as shown in FIG. 3) is a container that can be made substantially airtight. In this example, the main body 100a and its upper part are closed. A gas supply / exhaust portion 2a (gas supply / exhaust space) having a large number of gas through holes 20a is provided at the bottom of the main body 100a. A gas supply / exhaust pipe 3a is connected to the gas supply / exhaust section 2a. The gas supply / exhaust pipe 3a has a gas supply pipe system 4a for supplying carbon dioxide gas, and a gas supply / exhaust pipe 3a for reducing the pressure in the processing vessel 1a. A suction pipe system 5a provided with a suction pump 6a for performing the operation is connected. Further, an exhaust pipe 7a for exhausting the gas supplied into the processing container 1a is connected to an upper portion of the processing container 1a. In the drawings, reference numerals 8a to 10a denote on-off valves provided in each piping system.

  In one embodiment of the method of the present invention in FIG. 4 (an embodiment aiming at the operation of FIG. 1), a powdery and granular material is formed in the processing chamber 1a so that a large gap is not formed between the processing chamber 1a and the inner wall of the processing chamber. Carbonated solid B obtained by carbonating the uncarbonated Ca-containing raw material is placed. This allows the carbon dioxide gas introduced from the gas supply / exhaust portion 2a at the bottom of the processing vessel to flow so as to pass through the inside of the solidified carbon dioxide (gap between raw material particles = through-hole). The carbonated solid B contains an appropriate amount of water (usually, an amount of water necessary and sufficient for the carbonation treatment or an amount close thereto).

After the carbonated solid B is put in the processing container 1a as described above, the lid 101a is attached to the processing container 1a to make the processing container 1a airtight, and then the processing is performed by suction using the suction pump 6a of the suction pipe system 5a. The container 1a is evacuated. As a result, the inside of the carbonated solidified body B (processing vessel) is depressurized, and in the carbonated solidified body B, an appropriate distribution state of water (pore water) as described above, that is, water adhering to the surface of each raw material particle. As a result, a state is realized in which gaps that are uniformly present and serve as a path for CO ₂ between the raw material particles are appropriately secured.

Next, the suction pipe system 5a and the gas supply pipe system 4a are switched by operating the on-off valves 8a and 9a, and carbon dioxide gas is supplied from the gas supply pipe system 4a into the processing vessel 1a for a certain period (for example, several hours to several hundred hours). Supply). After the carbon dioxide gas is introduced into the gas supply / exhaust portion 2a, it is blown into the carbonized solid body B above from the gas through hole 20a. A part of the carbon dioxide gas passing through the carbonated solidified body B reacts with Ca ions eluted from the raw material particles to the water adhering to the surface thereof, and CaCO ₃ precipitates on the surface of the raw material particles, and this serves as a binder to serve as a binder. The consolidated state of B is further enhanced. The remainder of the carbon dioxide gas passes through the solidified carbon dioxide B and is discharged from the exhaust pipe 7a to the outside of the processing vessel 1a. In some cases, the carbon dioxide gas may be supplied into the processing vessel 1a with the on-off valve 10a of the exhaust pipe 7a closed, but in that case, the on-off valve 10a is sometimes opened and the processing vessel is opened. It is preferable that the gas accumulated in the processing chamber 1a is released so that the concentration of carbon dioxide in the processing chamber 1a is maintained at a predetermined level or more. Further, the gas may be released by reducing the pressure in the processing container 1a, and thereafter, a predetermined concentration of carbon dioxide may be introduced. After the above-described supply of carbon dioxide gas has been performed for a certain period of time, the solidified carbon dioxide B is taken out of the processing container 1a. Note that the above-described “decompression treatment-carbonation treatment” may be performed by repeating this plural times.

  In another embodiment of the method of the present invention in FIG. 4 (an embodiment aiming at the operation of FIG. 2), similarly to the above-described embodiment, the solidified carbonate B is placed in the processing chamber 1a. In this embodiment, first, sufficient water is contained in the carbonated solidified body B. As a method for this, the processing container may be immersed in water in a water tank with the upper portion of the processing container 1a opened. Alternatively, a sufficient amount of water may be sprinkled from the upper portion of the carbonated solid B. In addition, water may be contained in the solidified carbonized body B by immersion or water spraying before being put into the processing container 1a.

After sufficient water is contained in the carbonated solidified body B as described above, the lid 101a is attached to make the processing container 1a airtight, and then the processing is performed by suction using the suction pump 6a of the suction pipe system 5a. The container 1a is evacuated. As a result, the pressure inside the carbonated solidified body B (processing vessel) is reduced, and the air and water (interstitial water) in the carbonated solidified body B are pushed out from the carbonated solidified body, and pass through the gas through hole 20a and the gas supply / exhaust portion 2a. And is discharged from the processing container 1a. As a result, the appropriate distribution state of water (pore water) as described above in the solidified carbonated body B, that is, the water adhering to the surface is uniformly present on each raw material particle, and CO ₂ is present between the raw material particles as shown in FIG. A state in which a gap that becomes a road is appropriately secured is realized.

  Next, the suction pipe system 5a and the gas supply pipe system 4a are switched by operating the on-off valves 8a and 9a, and carbon dioxide gas is supplied from the gas supply pipe system 4a into the processing vessel 1a for a certain period (for example, several hours to several hundred hours). ) Is supplied, and the carbonation solidified body B is recarbonated. The conditions, effects, and the like of this recarbonation treatment are the same as those of the above-described embodiment. After the re-carbonation treatment, the solidified carbonate B is taken out of the processing vessel 1a. Note that the above-described “decompression treatment-carbonation treatment” may be performed by repeating this plural times.

  FIG. 5 shows an example of an implementation state of a method of permeating carbon dioxide gas inside a carbon dioxide solidified body in a carbon dioxide gas atmosphere in the method of the present invention, and shows a state in which a processing vessel is longitudinally sectioned. The processing container 1b is a container that can be made substantially airtight, and in this example, includes a main body 100b and a lid 101b that closes an upper part of the main body 100b. A gas supply / exhaust pipe 3b is connected to the main body 100b. The gas supply / exhaust pipe 3b has a gas supply pipe system 4b for supplying carbon dioxide gas and suction for reducing pressure in the processing vessel 1b. A suction pipe system 5b provided with a pump 6b is connected. Further, an exhaust pipe 7b for exhausting the gas supplied into the processing container 1b is connected to an upper portion of the processing container 1b. In addition, in the drawings, reference numerals 8b to 10b denote on-off valves provided in each piping system.

In one embodiment of the method of the present invention shown in FIG. 5 (an embodiment aiming at the operation of FIG. 1), carbonation solidification obtained by carbonizing and solidifying a powdery granular uncarbonated Ca-containing raw material in the processing vessel 1b. Body B is put in. The carbonated solid B contains an appropriate amount of water (usually, an amount of water necessary and sufficient for the carbonation treatment or an amount close thereto). Next, the lid 101b is attached to the processing container 1b to make the processing container 1b airtight, and thereafter, the inside of the processing container 1b is evacuated by suction using the suction pump 6b of the suction pipe system 5b. As a result, the inside of the carbonated solidified body B (processing vessel) is depressurized, and in the carbonated solidified body B, an appropriate distribution state of water (pore water) as described above, that is, water adhering to the surface of each raw material particle. As a result, a state is realized in which gaps that are uniformly present and serve as a path for CO ₂ between the raw material particles are appropriately secured.

Next, the suction pipe system 5b and the gas supply pipe system 4b are switched by operating the on-off valves 8b and 9b, and carbon dioxide gas is supplied from the gas supply pipe system 4b into the processing vessel 1b for a certain period (for example, several hours to several hundred hours). Supply). Part of the carbon dioxide gas supplied into the processing vessel 1b penetrates from the surface of the solidified carbon dioxide B into the inside, reacts with Ca ions eluted from the raw material particles to the water attached to the surface, and CaCO ₃ is formed on the surface of the raw material particles. It precipitates and serves as a binder to enhance the solidified state of the solidified carbonic acid B. The remainder of the carbon dioxide gas is discharged from the exhaust pipe 7b to the outside of the processing vessel 1b. In some cases, the carbon dioxide gas may be supplied into the processing vessel 1b with the on-off valve 10b of the exhaust pipe 7b closed, but in that case, the on-off valve 10b is sometimes opened and the processing vessel is opened. It is preferable that the gas accumulated in the processing vessel 1b be released so that the concentration of carbon dioxide in the processing vessel 1b is maintained at a predetermined level or more. Further, the gas may be released by reducing the pressure in the processing vessel 1b, and thereafter, a predetermined concentration of carbon dioxide may be introduced. After the above-described supply of carbon dioxide gas has been performed for a certain period of time, the solidified carbon dioxide B is taken out of the processing container 1b. Note that the above-described “decompression treatment-carbonation treatment” may be performed by repeating this plural times.

  In another embodiment of the method of the present invention in FIG. 5 (an embodiment aiming at the operation of FIG. 2), similarly to the above-described embodiment, a solidified carbonic acid B is placed in the processing vessel 1b. In this embodiment, first, sufficient water is contained in the solidified carbonated body B. As a method for this, the processing vessel 1b may be immersed in water in a water tank with the upper part of the processing vessel 1b opened. Alternatively, a sufficient amount of water may be sprinkled from the upper part of the solidified carbonate 1B. In addition, water may be contained in the solidified carbonized body B by immersion or water spraying before being put into the processing container 1b.

After sufficient water is contained in the carbonated solidified body B as described above, the lid 101b is attached to the processing vessel 1b to make it airtight, and thereafter, the processing is performed by suction using the suction pump 6b of the suction pipe system 5b. Evacuation is performed from inside the container 1b. As a result, the pressure inside the carbonated solidified body B (processing vessel) is reduced, and the air and water (pore water) in the carbonated solidified body B are extruded from the carbonated solidified body and discharged from the processing vessel 1b. As a result, the appropriate distribution state of water (pore water) as described above in the solidified carbonated body B, that is, the water adhering to the surface is uniformly present on each raw material particle, and CO ₂ is present between the raw material particles as shown in FIG. A state in which a gap that becomes a road is appropriately secured is realized.

  Next, the suction pipe system 5b and the gas supply pipe system 4b are switched by operating the on-off valves 8b and 9b, and carbon dioxide gas is supplied from the gas supply pipe system 4b into the processing vessel 1b for a certain period (for example, several hours to several hundred hours). ) Is supplied, and the carbonation solidified body B is recarbonated. The conditions, effects, and the like of this recarbonation treatment are the same as those of the above-described embodiment. After the re-carbonation treatment, the solidified carbonate B is taken out of the processing vessel 1a. Note that the above-described “decompression treatment-carbonation treatment” may be performed by repeating this plural times.

The shape of the solidified carbonate obtained by the present invention is arbitrary, for example, the cross-sectional shape is circular, elliptical, triangular, polygonal or larger than quadrangle, star or the like, or the whole shape is spherical, elliptical, tetrahedral or more. Any shape such as a polyhedral shape, a conical shape, a columnar shape, and a tetrapot shape can be used.
In addition, the solidified carbonate obtained by the present invention can be used as a stone for fishing and reef construction, a stone for rocky shore, a stone for water purification, a stone for water-permeable pavement, a block for water-permeable covering, a block for a buried drain, a hydroponic cultivation It can be used for various uses including a base material for water, a filter for water purification, a container for water supply, and the like.

[Example 1]
The following carbonated solids of the present invention and comparative examples were produced.
・ Example of the present invention A steelmaking slag having a maximum particle size of 3 mm was conditioned so as to have a moisture content of 8%, and was filled into a 1 m × 1 m × 1 m mold frame capable of being airtight and compacted appropriately. Thereafter, the pressure inside the mold was reduced to 0.2 atm. Thereafter, an exhaust gas containing 30% of carbon dioxide gas was blown in at a supply rate of 7 Nm ³ / hr for 3 days, and the slag packed layer was carbonated and solidified to obtain a carbonized solid. 100mm diameter of any portion of the carbonated solid, cut five cylindrical carbonated solid of length 200 mm, and the carbonated solid I ₁ ~I ₅ of the present invention embodiment.

・ Comparative example A steelmaking slag having a maximum particle size of 3 mm was humidified so as to have a water content of 8%, filled in a 1 m × 1 m × 1 m formwork, and then appropriately compacted, and then an exhaust gas containing 30% carbon dioxide gas. Was blown at a supply rate of 7 Nm ³ / hr for 3 days to carbonize and solidify the slag packed layer to obtain a carbonized solid. 100mm diameter of any portion of the carbonated solid, cut five cylindrical carbonated solid of length 200 mm, and the carbonated solid _C 1 -C ₅ comparative example.
For carbonated solid _{I 1 ~I 5, C 1 ~C} 7 of the present invention and comparative example Examples obtained as described above, CO ₂ content of the (CO ₂ amount calculated from the CaCO ₃ content) Measurement At the same time, the compressive strength was measured. The results are shown in Table 1, and it can be seen that the carbonated solidified product of the present invention example has an increased amount of CO ₂ absorption and an increased compressive strength as compared with the comparative example.

[Example 2]
The following carbonated solids of the present invention and comparative examples were produced.
・ Example of the present invention A slag (dephosphorized slag) having a particle size distribution in which the maximum particle size is about 10 mm and the ratio of particles having a particle size of 0.1 mm or less is about 15 mass% is filled in a 1 m × 1 m × 1 m formwork. Then, after compacting appropriately, carbon dioxide gas was blown in at a supply rate of 6 Nm ³ / hr for 3 days to carbonize and solidify the slag packed layer to obtain a carbonized solid.
Five columnar carbonized solidified bodies having a diameter of 100 mm and a length of 200 mm were cut out from an arbitrary portion of the carbonated solidified body. These are immersed in water in a water tank to sufficiently contain water therein, and then immediately charged into a vacuum desiccator to reduce the pressure inside the vacuum desiccator (solidified carbonic acid) to 0.1 atm. Excess moisture was drained from the inside. Next, carbon dioxide gas (CO ₂ : 50%) was supplied into the vacuum desiccator at a supply rate of 0.01 Nm ³ / hr for 7 days to obtain carbonic solids I _{1 to} I ₅ of the present invention.

Comparative Example A slag (dephosphorized slag) having a maximum particle size of about 10 mm and a particle size distribution in which a ratio of particles having a particle size of 0.1 mm or less is about 15 mass% is filled in a 1 m × 1 m × 1 m formwork. After compacting appropriately, carbon dioxide gas was blown in at a supply rate of 6 Nm ³ / hr for 5 days to carbonize the slag packed layer to obtain a carbonized solid. 100mm diameter of any portion of the carbonated solid, cut seven cylindrical carbonated solid of length 200 mm, to obtain a carbonated solid _C 1 -C ₇ of the comparative example.

For carbonated solid _{I 1 ~I 5, C 1 ~C} 7 of the present invention and comparative example Examples obtained as described above, CO ₂ content of the (CO ₂ amount calculated from the CaCO ₃ content) Measurement The results obtained are shown in FIG. According to this, the solidified carbon dioxide of the present invention has a significantly increased CO ₂ content as compared with that of the comparative example, although the total carbon dioxide gas supply is smaller than that of the comparative example. I have.
For carbonated solid C ₇ of the comparative examples and carbonated solid I ₁ of the present invention example shows the results of the compressive strength was measured in Figure 7. The compressive strength was measured with an Amsler tester after polishing the end face of the sample. According to FIG. 7, it can be seen that the solidified carbonate of the present invention has a significantly increased compressive strength as compared with that of the comparative example.

Then, the carbonated solid C ₇ of the comparative examples and carbonated solid I ₁ of the present invention example was cut at an arbitrary position, shows the results of measuring the roughness of the cut surface in FIG. According to this, the surface roughness of the cut surface of the solidified carbonate of the present invention is considerably smaller than that of the comparative example. The reason for this is that, in the carbonated solidified body of the comparative example, the amount of CaCO ₃ generated by the carbonation reaction is small, so that a part of the slag particles is peeled off at the time of cutting, and the surface becomes rough. This is because the solidified body generates a large amount of CaCO ₃ , and the slag particles are less likely to be separated during cutting. In addition, FIG. 9 shows a microscope enlarged photograph of a cut surface of the solidified carbonate of the present invention and the comparative example. According to this, as compared with the comparative example shown in FIG. 9A, in the example of the present invention shown in FIG. 9B, the ratio of the pores is considerably small, and the amount of generated CaCO ₃ is greatly increased. It turns out that it is.

Explanatory drawing which shows the principle by which the distribution state of water in a raw material filling layer or a carbonation solidification body becomes uniform in one Embodiment of this invention. In another embodiment of the present invention, an explanatory view showing the principle of uniform distribution of water in a raw material packed bed or a carbonated solidified body. Explanatory drawing which shows one Embodiment of this invention in the state which carried out the longitudinal cross section of the mold. Explanatory drawing which shows the other embodiment of this invention in the state which carried out the longitudinal section of the processing container. Explanatory drawing which shows the other embodiment of this invention in the state which carried out the longitudinal section of the processing container. For carbonated solid of the present invention and comparative example Example obtained in Example 2, a graph showing the result of measuring the CO ₂ content The graph which shows the result of having measured the compressive strength about the carbonated solid body of this invention example obtained in Example 2, and a comparative example. The graph which shows the result of having measured the roughness of the cut surface about the carbonated solid body of this invention example obtained in Example 2, and a comparative example. Microscope enlarged photographs of cut surface structures of the carbonated solids of the present invention example and comparative example obtained in Example 2.

Explanation of reference numerals

  DESCRIPTION OF SYMBOLS 1 ... Mold frame, 1a, 1b ... Processing container, 2, 2a ... Gas supply / exhaust part, 3, 3a, 3b ... Gas supply / exhaust pipe, 4, 4a, 4b ... Gas supply pipe system, 5, 5a, 5b ... Suction Pipe system, 6, 6a, 6b: suction pump, 7, 7a, 7b: exhaust pipe, 8, 8a, 8b, 9, 9a, 9b, 10, 10a, 10b: on-off valve, 20, 20a: gas through hole, 100, 100a, 100b: Main body, 101, 101a, 101b: Lid, A: Raw material packed layer, B: Carbonated solid

Claims (7)

A method for producing a carbonized solid obtained by consolidating a powdery uncarbonated Ca-containing raw material by a carbonation reaction,
In causing the packed layer of the uncarbonated Ca-containing raw material to be solidified by the carbonation reaction, or in causing the carbonized solid obtained by solidifying the packed layer of the uncarbonated Ca-containing raw material by the carbonation reaction to cause the carbonation reaction again,
A method for producing a solidified carbonized product, comprising reducing the pressure inside the packed bed or the solidified carbonate containing moisture, and then causing a carbonation reaction in the packed bed or the solidified carbonate in the presence of carbon dioxide gas. A method for producing a carbonized solid obtained by consolidating a powdery uncarbonated Ca-containing raw material by a carbonation reaction,
In causing the packed layer of the uncarbonated Ca-containing raw material to be solidified by the carbonation reaction, or in causing the carbonized solid obtained by solidifying the packed layer of the uncarbonated Ca-containing raw material by the carbonation reaction to cause the carbonation reaction again,
After impregnating the inside of the packed bed or the solidified carbonate, water is discharged by depressurizing the inside of the packed bed or the solidified carbonate. A method for producing a solid carbonated product, wherein a carbonation reaction is caused in the presence of carbon dioxide gas. A method for producing a carbonized solid obtained by consolidating a powdery uncarbonated Ca-containing raw material by a carbonation reaction,
By causing a carbonation reaction in the presence of carbon dioxide in the packed bed of the non-carbonated Ca-containing raw material containing water, the packed bed is solidified into a solidified carbonate, and then water is contained in the solidified carbonate. , After which a part of the water is discharged by depressurizing the inside of the solidified carbon dioxide, and thereafter, the carbonation is caused to occur again in the presence of carbon dioxide in the solidified carbonic acid. Manufacturing method of solidified body.   A method for producing a carbonated solidified product obtained by consolidating a powdery uncarbonated Ca-containing raw material by a carbonation reaction, wherein water is contained inside the packed layer of the uncarbonated Ca-containing raw material, and A part of the water is discharged by reducing the pressure, and thereafter, a carbonation reaction is caused in the packed bed in the presence of carbon dioxide gas, whereby the packed bed is solidified to form a carbonized solid, and then, After water is contained inside the solidified body, a part of the water is discharged by reducing the pressure inside the carbonized solidified body, and thereafter, the carbonated solidified body is again caused to undergo a carbonation reaction in the presence of carbon dioxide gas. A method for producing a solidified carbonated product.   By immersing the filled layer of the uncarbonated Ca-containing raw material or the packed layer of the uncarbonated Ca-containing raw material in the carbonation reaction in water, The method for producing a solidified carbonate according to any one of claims 2 to 4, wherein the pressure is reduced inside the packed layer or the solidified carbonate after the inclusion.   By sprinkling the packed layer of the uncarbonated Ca-containing raw material or the packed layer of the uncarbonated Ca-containing raw material onto the solidified carbonized solidified by the carbonation reaction, water is contained inside the packed bed or the solidified carbonic acid. The method for producing a solidified carbonate according to any one of claims 2 to 4, wherein the pressure of the inside of the packed layer or the solidified carbonate is reduced.   In the step of depressurizing the inside of the carbonized solid obtained by consolidating the packed layer of the carbonated Ca-containing raw material or the packed layer of the non-carbonated Ca-containing raw material by the carbonation reaction, the inside of the packed layer or the carbonized solid is reduced by 0.8%. The method for producing a solidified carbonic acid product according to any one of claims 1 to 6, wherein the pressure is reduced to an atmospheric pressure or less.

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