JP4591082B2 - Solidified body manufacturing method and on-site solidified body construction method - Google Patents

Description

  The present invention relates to a method for producing a solidified body using a granular material of a carbonated solidified body obtained by solidifying a powdered uncarbonated Ca-containing raw material by a carbonation reaction, and a method for constructing an in-situ solidified body. is there.

As one of the methods for making slag generated in the steel manufacturing process, carbonaceous solidified slag in granular form using uncarbonated Ca (CaO and / or Ca (OH) ₂ ) contained therein A method for obtaining a blocked carbonated solid body is known (for example, Patent Document 1). In this method, powdery slag to which moisture is added is filled into a mold, and carbonation gas is blown into this slag filling layer to cause a carbonation reaction in uncarbonated Ca contained in the slag. The slag filling layer is consolidated using the calcium carbonate produced in step 1 as a main binder to obtain a blocked carbonated solidified body.
JP-A-11-71160

In the production of such a carbonate solidified body, it is considered that the reaction between uncarbonated Ca and CO ₂ in the slag proceeds via water existing around each slag particle. That is, CO ₂ flowing between the slag particles is dissolved in the water (surface adhering water) existing on the surface of the slag particles, and Ca ions are eluted from the slag side, and the dissolved CO ₂ and Ca ions are dissolved and eluted in the water. It is considered that CaCO ₃ precipitates on the surface of the slag particles due to the reaction (carbonation reaction). The CaCO ₃ deposited on the surface of the slag particles serves as a main binder for bonding the slag particles together, and the entire slag packed layer is consolidated (carbonized).

  Such a carbonic acid solidified production technique 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 carbonated solids produced can be used as a replacement for conventional concrete products in various applications including civil engineering and building materials for road laying and construction, and submerged materials for algae and fish reefs. As a material for underwater subsidence, especially for algae and fish reefs, it offers superior performance compared to concrete products in terms of providing a favorable environment for seaweed growth and aquatic life. Is known to have

  However, the carbonated solid body produced as described above is a porous body in which raw material particles are consolidated by using calcium carbonate produced by the carbonation reaction as a binder, so it has higher strength (compressive strength) than concrete products. ) Is difficult to produce, which may cause problems such as cracks during transportation and use. In particular, it is necessary to add a large amount of water to slag with a high fine powder content. However, if the amount of water added is large, a continuous phase of water is generated inside the slag packed bed, and a non-ventilated region is likely to occur. Insufficient carbonation reaction will not occur. On the other hand, if the amount of water added is reduced in order to avoid this, the carbonation reaction will not occur sufficiently due to the lack of water. For this reason, in either case, the amount of calcium carbonate that binds between the raw material particles is insufficient, and sufficient strength of the carbonate solidified product cannot be ensured.

In addition, among the slag generated in the steel manufacturing process, some slags typified by hot metal desulfurization slag have a high free CaO (unpreceded CaO) content and a fine powder ratio compared to other slags. Although there are many features, it is very difficult to produce a carbonate solid of appropriate quality using such powdery slag containing a large amount of free CaO as a raw material. That is, in the case of a slag containing a large amount of free CaO, even if the raw material particles are covered with the calcium carbonate layer generated by the carbonation reaction to cause intergranular bonding, a large amount of free CaO remains in the raw material particles. Hydration expansion occurs in the raw material particles over time, and the carbonate solidified body collapses due to expansion cracking. Moreover, the solidified carbonic acid obtained from powdery slag with a high proportion of fine powder tends to cause insufficient strength for the reasons described above. Furthermore, in addition to the above-mentioned problems of expansion cracking of carbonic acid solidified bodies and insufficient strength, when submerged in the sea as a seaweed settlement base, etc., (1) a large amount of free CaO remaining in the raw material particles is in the water. Elution may cause environmental pollution such as high pH of seawater. (2) High pH of seawater produces white precipitate (magnesium hydroxide), which is not a harmful substance, but is generated. Since the initial state is a gel, the carbonate solidified body cannot function as a seaweed settlement base. (3) There is also a problem that turbidity may occur when precipitated in water because the fine powder contained in a large amount cannot be sufficiently carbonated.
For the reasons described above, conventionally, it is considered difficult to use slag containing a large amount of free CaO such as hot metal desulfurization slag and having a high proportion of fine powder as a raw material for the solidified carbonate.

Furthermore, in the conventional manufacturing method as described above, the carbonized solid can be manufactured only in a place where a carbon dioxide gas source exists, and therefore, it is necessary to transport from a manufacturing place to a use place even at a long distance. There is a costly disadvantage. Needless to say, on-site construction such as concrete is impossible.
Therefore, the object of the present invention is to solve such problems of the prior art, stably obtain a solidified body having an appropriate quality even from a raw material having a high proportion of fine powder, and a place where there is no carbon dioxide source However, it is providing the manufacturing method of the solidified body which can be manufactured or carried out on-site, and the construction method of an on-site solidified body.
Another object of the present invention is to stabilize a solid product having an appropriate quality with a small amount of free CaO even from powdered slag containing a large amount of free CaO such as hot metal desulfurization slag and having a high proportion of fine powder. It is providing the manufacturing method of the solidified body which can be obtained by this, and the construction method of an on-site solidified body.

  In order to solve the above-mentioned problems of the prior art, the present inventors are not limited to the conventional method for producing a solidified carbonic acid, in which carbon dioxide gas is blown into a raw material packed layer formed in a mold, and contain uncarbonated Ca. A new production method that can stably produce a solidified material of an appropriate quality using raw materials, particularly raw materials containing a large amount of free CaO and having a high proportion of fine powders, was studied. As a result, first, a granular uncarbonated Ca-containing raw material to which moisture has been added is granulated in the presence of carbon dioxide gas, and a carbonation reaction is caused in the granulation process, whereby a granulated product of carbonated solidified product is obtained. It turns out that it is obtained. In such a manufacturing method, it is better that the raw material contains a certain amount of fine powder, and therefore the granulation is better. Therefore, a raw material with a high proportion of fine powder, which is difficult to use in the conventional method, and further free CaO such as hot metal desulfurization slag. It was found that even if a raw material containing a large amount and containing a large proportion of fine powder was used, a carbonate solid (granulated product) of appropriate quality could be produced. However, what is obtained by the above-mentioned manufacturing method is a granular carbonate solidified body, and this granular carbonate solidified body is not such that it can become a seaweed settlement base like the carbonate solidified body produced using a mold. . Then, using this granular carbonate solidified body, as a result of investigating a method for obtaining a block solidified solid mass or on-site solidified body, unreacted free CaO remains in the granular carbonate solidified body, By solidifying (hydrating and curing) a kneaded product of this granular carbonated solid with a pozzolanic reactive substance and water, the solidified product of an appropriate quality is obtained without significantly impairing the properties of the solid carbonate. Was found to be obtained.

The present invention has been made based on such findings, and the features thereof are as follows.
[1] consists of carbonated solid granules obtained al a by consolidating the non-carbonated Ca-containing feedstock is contacted with carbon dioxide during the granulation by carbonation reaction, and the free CaO content (however, CaO A granular carbonate solid having a converted Ca (OH) ₂ content of 1 mass% or more is kneaded with a silica-containing substance having pozzolanic reactivity and water, and the kneaded product is converted into a granular carbonate solid. A method for producing a solidified product, comprising solidifying by a reaction between a free CaO contained and a silica-containing substance having pozzolanic reactivity.
[2] A method for producing a solidified body according to the above-mentioned [1], wherein a plant fertilizer component is further added to the granular carbonate solidified body and kneaded.

[3] The method for producing a solidified body according to the above [1] or [2] , wherein at least a part of the uncarbonated Ca-containing raw material is hot metal desulfurization slag.
[4] A vegetation plate comprising a solidified body obtained by the production method of any one of [1] to [3 ] above.

[5] consists carbonated solid granules obtained al a by consolidation in carbonation reaction is contacted with carbon dioxide in the granulation in a non-carbonated Ca-containing material, and a free CaO content (however, CaO A granular carbonate solid having a converted Ca (OH) ₂ content of 1 mass% or more is kneaded with a silica-containing substance having pozzolanic reactivity and water, and the kneaded product is placed in the construction section. An on-site solidified body construction method characterized in that it is solidified by a reaction between free CaO contained in the granular carbonate solidified body and a silica-containing substance having pozzolanic reactivity.
[6] The construction method of the on-site solidified body according to the construction method of [5 ] above, wherein a plant fertilizer component is further added to the granular carbonate solidified body and kneaded.
[7] A method for constructing an in-situ solidified product according to the construction method of [5] or [6 ] above, wherein at least a part of the raw material containing uncarbonated Ca is hot metal desulfurization slag.

The granular carbonated solid used in the production method and the construction method of the present invention is obtained by solidifying the carbonated raw material containing the uncarbonated Ca-containing raw material by a carbonation reaction. In particular, it is possible to stably obtain a granular carbonate solid body in which carbonation is effectively generated even from a raw material having a high content of free CaO such as hot metal desulfurization slag and a large proportion of fine powder, and In the manufacturing method and construction method, the characteristics of the carbonate solidified body are greatly increased by the solidification action (hydration hardening) utilizing the reaction between the free CaO remaining in the granular carbonate solidified body and the silica-containing substance having pozzolanic reactivity. Without losing, a solidified body containing a granular carbonate solidified body as a main material can be obtained.
In addition, according to the method of the present invention, the solidified body can be produced or applied on-site at any location as long as there is a granular carbonate solidified body produced in advance and a silica-containing substance having pozzolanic reactivity.

In the method for producing a solidified body of the present invention, it is obtained by bringing an uncarbonated Ca-containing raw material into contact with carbon dioxide gas and solidifying by a carbonation reaction, and a free CaO content (however, Ca (OH) in terms of CaO) ₂ ). The same applies hereinafter) to a granular carbonate solid having a mass% of 1% or more, a pozzolane-reactive silica-containing substance and water are added and kneaded, and this kneaded product is free CaO contained in the granular carbonate solid. A solidified product is obtained by solidifying by a reaction between a silica-containing substance having pozzolanic reactivity.
First, the granular carbonate solid body which becomes the main material of the solidified body manufactured by this invention is demonstrated.
The granular carbonate solidified body is obtained by bringing an uncarbonated Ca-containing raw material into contact with carbon dioxide gas and solidifying it by a carbonation reaction, and the raw material and production method are not particularly limited. As this granular carbonate solidified body, for example, carbonic acid gas is blown into a raw material layer formed in a mold or piled up at an appropriate place as in the conventional method to produce a carbonized solidified body, and this is crushed (further , Obtained by sizing treatment if necessary), a similar carbonized solidified product that is partially or completely disintegrated into particles due to insufficient carbonation, a product obtained by carbonation granulation described later, etc. One or more of these can be used.

In the present invention, since the solidified body is produced by hydration curing utilizing the reaction between the free CaO contained in the granular carbonate solidified substance and the silica-containing substance having pozzolanic reactivity, the granular carbonated solid form contains free CaO (however, Ca (OH) ₂ is contained, and so on). That is, the raw granular carbonated Ca-containing raw material that is the raw material contains free CaO, and in the carbonation step, the entire amount of free CaO is not carbonized, but a part remains as free CaO. is required. When the free CaO content of the granular carbonate solid is less than 1 mass%, the elution of CaO that reacts with the silica-containing material having pozzolanic reactivity is not sufficient when producing the solid, and the necessary hydration curability is obtained. Absent. For this reason, the free CaO content of the granular carbonate solidified body is 1 mass% or more, preferably 3 mass% or more.
However, if free CaO remains excessively in the granular carbonate solidified body, free CaO that cannot be reacted with the silica-containing substance having pozzolanic reactivity remains during the production of the solidified body, and expansion caused by this free CaO Since there exists a possibility of a crack and elution of CaO, it is preferable that the content of free CaO in a granular carbonate solidified body shall be 7 mass% or less.
Moreover, the particle size of the granular carbonate solidified body is not particularly limited, but those having a particle size distribution of about 1 to 5 mm are easy to granulate. However, it is possible to granulate those having a larger particle size (for example, 10 mm or more).

Although there is no special restriction | limiting in the kind of granular uncarbonated Ca containing raw material used as the raw material of a granular carbonate solidified body, For example, the slag etc. which generate | occur | produced in the concrete or steel manufacturing process are mentioned. The uncarbonated Ca contained in the uncarbonated Ca-containing raw material, that is, CaO and / or Ca (OH) ₂ suffices to be contained at least as a part of the composition of the solid particles, and therefore CaO as a mineral. In addition to Ca (OH) ₂ , 2CaO · SiO ₂ , 3CaO · SiO ₂ , glass, and the like that are present in solid particles as part of the composition are also included.
In addition, the kind of non-carbonated Ca-containing raw material and preferable conditions will be described in detail later.

The granular carbonate solidified material used in the present invention is obtained by carbonating and granulating a granular uncarbonated Ca-containing raw material, that is, a carbonation reaction during the granulation of an uncarbonated Ca-containing raw material. Solidified carbonate solidified granules (free CaO content: 1 mass% or more)
It is preferable that Such a carbonated granulated product is sufficiently carbonized to the inside because a carbonation reaction occurs during granulation of the raw material and the granulated product is carbonated, so that the raw material or hot metal containing a large proportion of fine powder. Even from raw materials with high free CaO content such as desulfurized slag and a high proportion of fine powder, stable granular carbonate solidified with low disintegration due to hydration expansion and reduced free CaO content to the necessary minimum It is because it can obtain.

This carbonate solidified granulated product can be obtained by granulating a powdery uncarbonated Ca-containing raw material containing moisture in the presence of carbon dioxide gas and solidifying the raw material in this granulation by a carbonation reaction. it can.
In the granulation of a powdery raw material containing moisture, the raw material containing a certain amount of fine powder has better granulation properties. Since the carbonated granulation is also a method for solidifying while carbonizing a powdered uncarbonated Ca-containing raw material, the raw material preferably contains a certain amount of fine powder in order to obtain high granulation properties. . From such a viewpoint, it is preferable to use a non-carbonated Ca-containing raw material having a ratio of particles having a particle size of 0.3 mm or less of 30 mass% or more.

The method for producing a granular carbonate solidified body using carbonation granulation generates a carbonation reaction during the granulation of the raw material, so that the raw material and carbon dioxide gas can be efficiently contacted, and as described above, The amount of free CaO remaining in the solidified granulated product can be reduced to the necessary minimum. For this reason, even a raw material containing a large amount of free CaO, for example, a raw material having a free CaO content of 10 mass% or more that could not be used in the prior art can be used without any problem.
Therefore, even if the slag has a high content of free CaO and a high proportion of fine powder, such as hot metal desulfurization slag, which can not be used in the prior art, it can be used without problems as a raw material. Especially suitable for. In addition, the hot metal desulfurization slag contains sulfur (CaS), but in carbonation granulation, the raw material and carbon dioxide gas come into efficient contact with each other, so that the sulfur content is also oxidized and stabilized. .

As described above, the reaction between uncarbonated Ca and CO _{2 in the} granular uncarbonated Ca-containing material is caused by CO flowing between the material particles in the water (surface adhering water) present on the surface of the material particles. _As Ca ₂ dissolves, Ca ions are eluted from the raw material particle side, and the CO ₂ dissolved and eluted in water reacts with Ca ions (carbonation reaction) to precipitate CaCO _{3 on the} surface of the raw material particles. Is. Also, moisture is required to granulate the powdery raw material. For this reason, the uncarbonated Ca-containing raw material needs to contain an appropriate amount of moisture. Therefore, moisture is added to the uncarbonated Ca-containing raw material as necessary.
The granulation of the uncarbonated Ca-containing raw material is performed in the presence of carbon dioxide gas. For this reason, carbon dioxide gas or a carbon dioxide-containing gas (hereinafter referred to as “carbon dioxide gas” for convenience of description) is supplied to the raw material granulation part. Details of these gases will be described later.

Usually, a granulator is used to granulate the uncarbonated Ca-containing raw material, the moisture-containing uncarbonated Ca-containing raw material is charged into the granulator, and carbon dioxide gas is introduced into the granulator. While stirring, the uncarbonated Ca-containing raw material is granulated by stirring (and rolling the granulated product). Thus, granulation is performed under the supply of carbon dioxide gas, whereby the granulated product of the uncarbonated Ca-containing raw material becomes a carbonated solidified body that is solidified by the carbonation reaction. In the granulation process in which such a granular carbonate solidified body is obtained, first, aggregates are formed while the raw material particles are carbonated, and this is solidified by carbonation, whereby a solidified body that is a nucleus is generated, and then this solidified body is produced. When the carbonation reaction proceeds while the particles aggregate or the raw material particles adhere to the solidified body, the diameter of the solidified body increases like a snowball, and a granular carbonized solidified body is obtained.
According to such a method for producing a granular carbonate solidified by carbonation granulation, the granulated product of uncarbonated Ca-containing raw material is grown while being solidified by carbonization, so that the inside of each raw material particle and the granulated product It can be carbonated firmly to the center. For this reason, even if it is a case where slag containing many free CaO and there are many fine powders is used as a raw material, the granular carbonate solidified body of appropriate quality can be manufactured.

  As the granulator, a pot type granulator (pot mixer), a drum type granulator (drum mixer), and a dish type granulator (disc pelletizer) are generally used. Any type of granulator can be used. In general, any granulator used for granulation of sintered raw materials (granulation of pseudo particles) can be applied without problems. In pot-type granulators and drum-type granulators (mixers), a blade for stirring is generally provided on the inner surface of the body (container), and the material is lifted and stirred by the blade as the body rotates. In addition, for example, a granulator that stirs a raw material in a rotating or non-rotating machine body using an independently rotating stirring blade may be used. The dish-type granulator is a granulator that performs granulation by rotating an inclined dish-shaped container.

  In addition, a method of supplying carbon dioxide gas into the granulator (raw material granulation unit) is also arbitrary. For example, (1) a gas supply pipe is inserted into the inside of an opening of a pot type or drum type granulator And a method of supplying carbon dioxide gas to the raw material during granulation by positioning the gas outlet of the gas supply pipe in the raw material, and (2) a granulator having a stirring means such as an independently rotating stirring blade In this case, the stirring means itself is provided with gas supply means (gas supply path, gas discharge port, etc.), and carbon dioxide gas is supplied to the raw material from this gas supply means. (3) Gas discharge port at the bottom of the granulator A method of supplying carbon dioxide gas into the raw material from this gas discharge port, (4) A method of making the inside of the granulator airtight or semi-airtight and making the inside of the machine a carbon dioxide atmosphere, (5) In the drum type granulator Carbon dioxide gas is supplied to the raw material granulation unit by an appropriate method such as supplying carbon dioxide from one end and discharging from the other end. It can be supplied.

1 and 2 show an embodiment of the present invention. FIG. 1 is a longitudinal sectional view of a granulator, and FIG. 2 is a sectional view taken along line II-II in FIG. In this embodiment, an uncarbonated Ca-containing raw material is granulated using a pot-type granulator in which a plurality of stirring blades 2 are provided on the inner surface of a rotationally driven body 1 (container). A gas supply pipe 3 is inserted into the inside from the opening of 1, and carbon dioxide gas is supplied into the uncarbonated Ca-containing raw material through the gas supply pipe 3.
An uncarbonated Ca-containing raw material x containing moisture is placed in the machine body 1, and the uncarbonated Ca-containing raw material x is stirred so as to be scraped up by the stirring blade 2 as the machine body 1 rotates, Granulated. During the granulation, the granulated product is carbonated by supplying carbon dioxide from the gas supply pipe 3, and a granular carbonated solid is obtained. Since this granular carbonate solid body grows with the progress of granulation and becomes larger in diameter, it is possible to obtain a granular carbonate solid body having an arbitrary diameter by adjusting the granulation time.

Next, a process for producing a solidified body using the above granular carbonate solidified body as a main material will be described.
In the production process of this solidified body, the granular carbonate solidified body, which is the main material, is kneaded with a silica-containing substance having pozzolanic reactivity and water, and this kneaded product is free CaO and pozzolana eluted from the granular carbonated solidified body. It is consolidated (hydrated and cured) by reaction with a reactive silica-containing substance.
The pozzolanic reactivity of a substance is a property that reacts with an external alkali to form insoluble lCaO-mSiO ₂ -nH ₂ O gel (CSH gel) and cures, and a pozzolanic reaction added to a granular carbonate solidified body. The silica-containing substance having the property causes a pozzolanic reaction with free CaO eluted from the granular carbonate solidified body, and generates an insoluble CSH gel. And a granular carbonate solidified body solidifies this CSH gel as a binder, and a desired solidified body is obtained.

In order to appropriately obtain the above-described effects, the silica-containing substance having pozzolanic reactivity is preferably a powder. Although there is no special restriction | limiting in the kind of such a substance, blast furnace granulated slag fine powder and fly ash are especially preferable, and 1 or more types chosen from these can be used.
Moreover, you may mix | blend an appropriate amount of 3rd components other than the silica containing material which has pozzolanic reactivity in a granular carbonate solidified body. As this 3rd component, the fertilizer component of a plant (land plant, seaweed) etc. are mentioned, for example. The plant fertilizer is preferably a substance containing one or more of nitrogen, phosphoric acid, potash, silicic acid and the like. In addition to commercially available fertilizers, blast furnace slag, hot metal dephosphorized slag, hot metal desiliconized Slag, what added other components to these slags, etc. can be used. Moreover, you may add 3rd components other than the fertilizer component of a plant according to the use of a solidified body.

The blending ratio of the silica-containing substance having pozzolanic reactivity in the raw material (solid raw material) composed of the third component to be blended as necessary is as follows: It is preferable to set it as about 5-15 mass%. If the content of the silica-containing material having pozzolanic reactivity is less than 5 mass%, the caking action by this silica-containing material may be insufficient. On the other hand, if the content exceeds 15 mass%, the solid carbonic acid solidified by the silica-containing material. Since the surface of this is covered, the characteristics of the granular carbonate solidified body may be lost.
In addition, in the case of blending the third component, from the gist of the present invention to obtain a solidified body using a granular carbonated solid body, the ratio of the granular carbonated solid body + the granular carbonated solid body in the third component Is suitably 50 mass% or more, preferably 70 mass% or more, more preferably 90 mass% or more. In addition, when a 3rd component is a fertilizer component of a plant, since normal fertilizer application amount is around 100 kg per 10 ares (depth 30cm), for example, it is 1 / 5000g / cm < ³ > -1 / 1000g in a raw material. / Cm ³ may be blended.

In addition, the amount of water is usually about 0.8 to 1.2 in terms of mass ratio to the silica-containing substance having pozzolanic reactivity, but depending on the water content of the granular carbonate solidified body. Adjusted.
A silica-containing substance having pozzolanic reactivity, water, and, if necessary, a third component are added to the granular carbonate solid, and this is kneaded using a mixer or the like. Then, this kneaded product is usually put in a mold or the like, molded, hydrated and cured, and after curing, de-framed to obtain a solidified body. In the case of a raw material having good shape retention, it may be removed immediately after being molded with a mold or the like, and hydrated and cured in that state.
The solidified body produced according to the present invention includes marine civil engineering materials such as fishing reef and alga reef formation stones, construction stones, vegetation base materials (for example, vegetation plates), hydroponics base materials It can be applied to various uses including water-purifying stones, water-filtering materials, water-permeable paving stones, and water-purifying filter materials.

  The solidified product produced according to the present invention has a very high water holding capacity because the individual granular carbonated solids constituting this are porous bodies having innumerable through-pores. Since a void in which a plant can be rooted is formed, a vegetation plate with high water retention, which is particularly suitable for directly planting a land plant, can be obtained. Such a vegetation plate is suitable for planting plants such as turf, etc. by installing it on the rooftops, terraces, verandas, etc. of gardens, greening zones around roads (including the median strip), etc. On road surfaces such as sidewalks, it can also be used as a permeable pavement plate with grass. By using such a vegetation plate with high water retention, the so-called heat island phenomenon can be suppressed by its water retention effect.

Next, the construction method of the on-site solidified body of the present invention will be described.
In the construction method of the on-site solidified body of the present invention, it is obtained by bringing a powdery uncarbonated Ca-containing raw material into contact with carbon dioxide gas and solidifying by carbonation reaction, and free CaO content (however, converted to CaO) In addition, a silica-containing substance having pozzolanic reactivity and water are kneaded into a granular carbonate solid having a Ca (OH) ₂ content of 1 mass% or more, and the kneaded product is placed in a construction section. The in-situ solidified body is constructed by solidifying by the reaction of the free CaO contained in the granular carbonate solidified body and the silica-containing material having pozzolanic reactivity.
In this in-situ solidified construction method, preferred conditions and production conditions of the granular carbonate solidified body, raw material blending conditions for the solidified body, and the like are the same as the solidified body production method described above.
In the on-site casting of the solidified body, a silica-containing substance having pozzolanic reactivity and water and, if necessary, a third component are added to the granular carbonate solidified body, and this is kneaded using a mixer or the like. And this kneaded material is poured into a construction part and hydrated and hardened to obtain a fixed solid body.

This on-site solidified body constitutes all or part of a civil engineering structure, a building, a roadbed structure, and the like. Civil engineering structures are not limited to those on land, but can also be applied to structures installed underwater. Moreover, it can be applied to vegetation bases, slope protection works, etc. for land.
The solidified body subjected to on-site construction according to the present invention has a very high water retention because the individual granular carbonated solids constituting this are porous bodies having innumerable through pores, and between the aggregated granular carbonated solids. Since a void in which a plant can be rooted is formed, a vegetation base with high water retention, which is particularly suitable for directly planting a land plant, can be obtained. Such a vegetation base is suitable for planting plants such as turf by installing it in gardens such as rooftops, terraces and verandas of buildings, greening zones around roads (including median strips), etc. On road surfaces such as sidewalks, it can also be used as permeable pavement with grass. By using such vegetation with high water retention, the water retention effect can also help to suppress the so-called heat island phenomenon.

Hereinafter, preferable production conditions for obtaining a carbonate solid from a granular uncarbonated Ca-containing raw material, particularly preferred production conditions for producing a granular carbonate solid by the above-mentioned carbonation granulation will be described.
There is no particular restriction on the particle size of the powdered uncarbonated Ca-containing raw material, but when producing a granular carbonate solidified product by carbonation granulation, the raw material containing a certain amount of fine powder as described above. However, the granulation property is good.
The powdery uncarbonated Ca-containing raw material is not particularly limited as long as it contains uncarbonated Ca as at least a part of the composition. However, the content of uncarbonated Ca is high and resources are recycled. In particular, slag, concrete (for example, waste concrete) generated in the steel manufacturing process is particularly preferable. Generally, the CaO content of slag generated in the steel manufacturing process (including CaO other than free CaO) is about 13 to 60 mass%, and the CaO content of concrete (for example, waste concrete) (CaO other than free CaO). Including)) is about 5 to 15 mass%, and since these are easily available, it can be said that they are extremely suitable materials as uncarbonated Ca-containing raw materials. Therefore, it is preferable 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 steel manufacturing process includes blast furnace slag, blast furnace granulated slag, blast furnace slag, decarburization slag, dephosphorization slag, desulfurization slag, Examples include steel slag such as silica slag and cast slag, ore reduction slag, and electric furnace slag. However, the present invention is not limited to these, and a mixture of two or more slags can also be used. .
Moreover, a considerable amount of iron (iron such as granular iron) is included in the slag generated in the steel manufacturing process, and slag that has undergone a recovery process of this iron (metal) may be used.
Among the slags as described above, from the viewpoint of granulation in the case of producing a granular carbonated solid body by carbonation granulation, the ratio of particles having a particle size of 0.3 mm or less is preferably 30 mass% or more. Examples of such slag include hot metal desulfurization slag and some decarburization slag that is powdery because it is easy to digest.
Moreover, when using slag, such as hot metal desulfurization slag, as a raw material, when there are too many fine powder ratios or free CaO content is too much, there are few fine powder ratios and / or free CaO content. A small amount of other slag may be mixed and used as a raw material.

Moreover, as concrete, the waste concrete etc. which were produced by the demolition of a building or a civil engineering structure etc. can be used, for example.
Examples of the non-carbonated Ca-containing material include mortar, glass, alumina cement, CaO-containing refractories, etc., in addition to the above slag and concrete, and one or more of these may be used alone or in combination, or slag And / or mixed with concrete.
These materials are crushed into powder as necessary and used as raw materials.
The uncarbonated Ca-containing raw material does not need to be solid particles whose entire amount contains uncarbonated Ca. That is, if the carbonation of the uncarbonated Ca contained in the uncarbonated Ca-containing raw material produces a sufficient amount of CaCO ₃ as a binder for the solidified carbonic acid, the uncarbonated Ca-containing raw material is converted into the uncarbonated Ca-containing raw material. Solid particles not containing may be contained. Examples of such solid particles include natural stone, sand, soluble silica, metal (for example, metallic iron, iron oxide) and the like. Moreover, blast furnace granulated slag can be used as a soluble silica source.

Among these, metallic iron, iron oxide, soluble silica, and the like, such as a fixing agent for sulfur and phosphorus in water, seaweeds, etc., when the carbonate solid produced by the method of the present invention is used as an underwater sedimentation material, 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 carbonated solid is not reduced.
Further, by adding a Cl ion-containing substance such as seawater to the uncarbonated Ca-containing raw material, and performing granulation and carbonation, the action of Cl ions contained in the water adhering to the surface of the raw material particles causes The elution rate of Ca ions in the surface-attached water can be increased, the production rate of calcium carbonate can be increased, and the production time can be shortened and the diameter of the granulated product can be increased.

As carbon dioxide gas (carbon dioxide gas or carbon dioxide-containing gas) used for causing a carbonation reaction in the raw material, for example, lime burning factory exhaust gas discharged in an integrated steel works (usually around CO ₂ : 25 vol%) And heating furnace exhaust gas (usually around CO ₂ : 6.5 vol%) are suitable, but are not limited thereto. In addition, if the CO ₂ concentration in the gas is too low, there arises a problem that the processing efficiency is lowered, but other problems are not exceptional. Therefore, the CO ₂ concentration is not particularly limited, but it is preferable to set the CO ₂ concentration to 3 vol% or more for efficient treatment.
Moreover, although there is no special restriction | limiting also in the supply amount of a carbon dioxide gas, when manufacturing a granular carbonate solidified body by carbonation granulation, as a general guideline, 1-4 m < ³ > / min * t (raw material ton) It is only necessary to secure a certain amount of gas supply. Further, although there is no particular restriction on the gas supply time (carbonation treatment time), as a guideline, when the supply amount of carbon dioxide gas becomes 3% or more of the mass of the uncarbonated Ca-containing raw material, generally the gas amount in terms of raw material 1t per 50 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 may be at normal temperature, but if the gas is higher than normal temperature, it is advantageous because the reactivity increases accordingly. However, if the temperature of the gas is excessively high, moisture of the raw material is dried or CaCO ₃ is decomposed into CaO and CO ₂ , so that such decomposition does not occur even when a high temperature gas is used. It is necessary to use gas.
Carbon dioxide gas is preferably supplied to the raw material in a humidified state in order to prevent the raw material from drying. Therefore, when supplying gas to the raw material, it is preferable to blow carbon dioxide gas into water to saturate H ₂ O, and then supply it to the raw material, thereby preventing the raw material from drying and promoting the carbonation reaction Can be made.

Using molten iron desulfurization slag (particle size 0.3 mm or less: 44 mass%, particle size 5 mm or less: 100 mass%) and granulated blast furnace slag as raw materials, carbonation granulation is performed with the raw material composition shown in Table 1, and granular carbonate solidified body Manufactured. In this carbonation granulation, after adding moisture (initial moisture) to the raw material, granulation is performed while supplying a CO ₂ -containing gas (CO ₂ : 20 vol%) using a granulator of the type shown in FIG. It was.
The granular carbonate solid body produced as described above was cured in the atmosphere for a predetermined period and then dried, and then the content of free CaO and the amount of CO ₂ fixed by carbonation were measured by component analysis. The measured values are shown in Table 1 together with the manufacturing conditions. As a reference example, Table 1 also shows the free CaO content of the steelmaking slag itself and the amount of CO ₂ fixed.

  The granular carbonate solidified products of Invention Examples 1 to 3 shown in Table 1 are mixed with 85 mass% and granulated blast furnace slag powder: 15 mass%, and kneaded with an appropriate amount of water (water / blast furnace granulated slag fine powder≈1). The kneaded product was put into a mold (φ48 mm × 20 mm), molded and cured, then deframed, and then solidified for about 12 hours. Further, the solidified body was subjected to wet air curing for 14 days and then subjected to a seawater immersion test. In this seawater immersion test, each solidified body was immersed in 0.5 L of seawater, and the change in pH of seawater with time was examined, and the presence or absence of precipitates was examined. The results are shown in FIG. 3, in which no solidified product (magnesium hydroxide) was formed and no excessive pH increase was observed (the pH of seawater is usually 7.8 to 8.3). degree).

1 shows an embodiment of a method for producing a granular carbonate solid used in the present invention, and is a longitudinal sectional view of a granulator. Sectional drawing which follows the II-II line in FIG. The graph which shows the result of the seawater immersion test in the Example of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Airframe 2 Agitation blade 3 Gas supply pipe x Raw material containing uncarbonated Ca

Claims (7)

Becomes non carbonated Ca-containing material from the granulator during carbonated solid granules obtained al a by in contact with carbon dioxide is consolidated by carbonation reaction, and the free CaO content (however, the terms of CaO Ca (OH) ₂ content is included.) Is 1 mass% or more of the granular carbonate solidified body, a pozzolane-reactive silica-containing substance and water are added and kneaded, and the kneaded product is contained in the granular carbonate solidified solid. A method for producing a solidified body, characterized by solidifying by reaction of CaO and a silica-containing substance having pozzolanic reactivity.   The method for producing a solidified product according to claim 1, wherein a plant fertilizer component is further added to the granular carbonated solidified product and kneaded. The method for producing a solidified body according to claim 1 or 2 , wherein at least a part of the uncarbonated Ca-containing raw material is hot metal desulfurization slag. Vegetation plate characterized by comprising the obtained solid material by any of the method according to claim 1-3. Becomes non carbonated Ca-containing material from the granulator during carbonated solid granules obtained al a by in contact with carbon dioxide is consolidated by carbonation reaction, and the free CaO content (however, the terms of CaO Ca (OH) ₂ content is contained.) After adding and kneading a silica-containing substance having pozzolanic reactivity and water to a granular carbonate solid body having a mass content of 1 mass% or more, the kneaded product is placed in a construction part, An on-site solidified body construction method characterized by solidifying by reaction of free CaO contained in a granular carbonate solidified body and a silica-containing substance having pozzolanic reactivity. 6. The construction method of the in-situ solidified body according to claim 5 , wherein a plant fertilizer component is further added to the granular carbonate solidified body and kneaded. The construction method of the on-site solidified body according to claim 5 or 6 , wherein at least a part of the uncarbonated Ca-containing raw material is hot metal desulfurization slag.

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