Carbonate-containing granular material production method

Abstract

Provided is a carbonate-containing granular material production method with which it is possible to produce a carbonate-containing granular material at a cost lower than when using conventional methods.　The present invention has a carbonation step for bringing, into contact with a carbonation-target granular material at a maximum temperature of higher than 0°C to lower than 100°C, either water, a carbonation accelerator, and at least one among a carbon dioxide-containing substance, a carbonate ion-containing water, and a hydrogen carbonate ion-containing water, or a carbonation accelerator and at least one among a carbon dioxide-containing water, a carbonate ion-containing water, and a hydrogen carbonate ion-containing water. The total amount of water brought into contact in the carbonation step is 1 mass% or more of the carbonation-target granular material. The carbonation accelerator contains bacteria. The bacteria are at least one selected from the genus Bacillus, the family Bacillaceae, the class Bacilli, the family Clostridiaceae, the family Micrococcaceae, the family Microbacteriaceae, or the family Comamonadaceae.

Description

Method for manufacturing carbon oxide-containing granular material

[0001] This invention relates to a method for producing a carbon oxide-containing granular material.

[0002] Steelmaking slag, including pre-processing slag, converter slag, electric furnace slag, and casting slag, generated at steel mills, is discharged onto a slag yard or steel plate after steelmaking and refining, and solidified by cooling. After the solidified steelmaking slag cools to room temperature, the particle size is adjusted using a crusher, and the iron content is recovered by passing it through a magnetic separator. It is then widely used as roadbed material, as well as for civil engineering, construction, and marine applications.

[0003] Since steelmaking slag contains CaO, using it directly as roadbed material can cause problems such as expansion. Therefore, when using steelmaking slag as roadbed material, it is being considered to carbonize the CaO contained in the steelmaking slag into calcium carbonate.

[0004] Patent Document 1 discloses a method for inline mineralization of water using carbon dioxide, carbonic anhydrase, and solid minerals. According to Patent Document 1, carbonic anhydrase is CO ２ It is disclosed that it acts as a catalyst to improve the dissolution rate in water.

[0005] Special Publication No. 2022-513451

[0006] The method disclosed in Patent Document 1 uses carbonic anhydrase, which is known to be expensive. Furthermore, since carbonic anhydrase is filled into the pipe, there is a possibility of clogging of the circulating water, resulting in maintenance costs. For this reason, the method disclosed in Patent Document 1 has the problem of high manufacturing costs for carbon oxide-containing granular material. The present invention has been made in view of these problems of the prior art, and its objective is to provide a method for manufacturing carbon oxide-containing granular material that can produce carbon oxide-containing granular material at a lower cost than conventional methods.

[0007] The means for solving the above problems are as follows: [1] A method for producing a carbon dioxide-containing granular material, comprising a carbonation step of contacting a granular material to be carbonated, having a maximum temperature greater than 0°C and less than 100°C, with water, a carbonation accelerator, and at least one of a carbon dioxide-containing substance, carbonate ion-containing water, and bicarbonate ion-containing water, or a carbonation accelerator and at least one of carbon dioxide-containing water, carbonate ion-containing water, and bicarbonate ion-containing water, wherein the total amount of water contacted in the carbonation step is 1% by mass or more of the granular material to be carbonated, and the carbonation accelerator contains bacteria, wherein the bacteria are at least one of the genus Bacillus, family Bacillaceae, class Bacillus, family Clostridaceae, family Micrococcaceae, family Microbacterialaceae, and family Comamonadaceae. [2] The bacterial concentration of the carbonation accelerator is 1.0 × 10 ５ A method for producing a carbon oxide-containing granular material according to [1], wherein the carbon dioxide content is CFU / g or more. [3] A method for producing a carbon oxide-containing granular material according to [1] or [2], wherein the carbon dioxide-containing granular material and / or water comprises the carbonation accelerator. [4] A method for producing a carbon oxide-containing granular material according to any one of [1] to [3], wherein the carbon dioxide-containing substance is a gas. [5] A method for producing a carbon oxide-containing granular material according to any one of [1] to [4], wherein the particle size of the carbon dioxide-containing granular material satisfies any of the following: the content of particles with a particle size of 0 to 75 μm exceeds 25% by mass, the content of particles with a particle size of 0 to 425 μm exceeds 30% by mass, the content of particles with a particle size of 0 to 2.36 mm exceeds 50% by mass, the content of particles with a particle size of 0 to 4.75 mm exceeds 65% by mass, and the content of particles with a particle size of 0 to 13.2 mm exceeds 85% by mass. [6] A method for producing a carbon oxide-containing granular material according to any one of [1] to [5], wherein the carbon dioxide-containing granular material is steelmaking slag.

[0008] The method for producing a carbon oxide-containing granular material according to the present invention uses a carbonation accelerator containing bacteria that promote the formation of carbon oxides of Ca, Mg, K, and Na contained in the granular material to be carbonated, thus enabling the production of a carbon oxide-containing granular material at a lower cost than conventional methods.

[0009] Figure 1 is a schematic diagram showing an example of a carbonation facility capable of carrying out the carbonation process in the method for producing carbon oxide-containing granular material according to this embodiment.

[0010] The present invention will be described in detail below through embodiments of the present invention. The following embodiments are preferred examples of the present invention, and the present invention is not limited in any way by these embodiments.

[0011] Figure 1 is a schematic diagram showing an example of a carbonation facility capable of carrying out the carbonation step in the method for producing carbon oxide-containing granular material according to this embodiment. The carbonation step in the method for producing carbon oxide-containing granular material according to this embodiment will be explained using Figure 1.

[0012] The carbonation equipment 10 includes a bottomed cylindrical container 12, an injection nozzle 14, a gas ejection nozzle 16, a stirring blade 18, and a thermocouple 20. In the carbonation process, water 22 and a carbonation accelerator 24 are supplied to the granular material to be carbonized 100 from the injection nozzle 14, and carbon dioxide gas-containing gas 26 is blown into the water 22 from the gas ejection nozzle 16 and stirred by the stirring blade 18. This allows carbon dioxide to dissolve in the water 22 as carbonate ions and bicarbonate ions and come into contact with the granular material to be carbonized 100. As a result, the carbonation reaction between oxides, hydroxides, and hydrates contained in the granular material to be carbonized 100 and carbonate ions and bicarbonate ions is promoted by the carbonation accelerator, making it possible to produce carbon oxide-containing granular material with a higher carbonation efficiency than conventional methods. Note that the carbon dioxide gas-containing gas 26 shown in Figure 1 is an example of a carbon dioxide gas-containing substance that is a gas.

[0013] The carbonated granular material 100 is CaO, MgO, K ２ O and Na ２ It is preferable that the substance contains one or more selected from O. Examples of the types of substances that can be used as the carbonated granular material 100 are shown in Table 1 below. In Table 1 below, "T-Fe" means the total amount of iron contained in the iron-containing compound. Also, "T-S" means the total amount of sulfur contained in the sulfur-containing compound.

[0014]

[0015] Carbonated granular material 100 is CaO, MgO, K ２ O and Na ２By including one or more selected from O, when water 22 is supplied, Ca, Mg, K, and Na elute into the water as ions from the carbonated granular material 100, so the formation of carbonates of these substances is promoted.

[0016] CaO, MgO, K ２ O and Na ２ From the viewpoint of including one or more selected from O, the carbonated granular material 100 is preferably steel slag. The carbonated granular material 100 is more preferably steelmaking slag among steel slags. As the steelmaking slag, the converter slag, electric furnace slag, secondary refining slag, and hot metal pretreatment slag shown in Table 1 above are preferably used.

[0017] Similarly, CaO, MgO, K ２ O and Na ２ For the reason of including one or more selected from O, the carbonated granular material 100 is preferably waste concrete or biomass incineration ash. Also, by supplying water 22 from coal ash generated in coal-fired power generation, flue gas desulfurization sludge, and general municipal waste incineration ash, the above metal ions elute. Therefore, coal ash, flue gas desulfurization sludge, and general municipal waste incineration ash can also be used as the carbonated granular material 100.

[0018] The particle size of the carbonated granular material 100 preferably satisfies any of the following particle sizes. - The content of particles with a particle size of 0 to 75 μm exceeds 25% by mass - The content of particles with a particle size of 0 to 425 μm exceeds 30% by mass - The content of particles with a particle size of 0 to 2.36 mm exceeds 50% by mass - The content of particles with a particle size of 0 to 4.75 mm exceeds 65% by mass - The content of particles with a particle size of 0 to 13.2 mm exceeds 85% by mass

[0019] When the particle size of the carbonated granular material 100 satisfies any of the above particle sizes, the surface area of the carbonated granular material 100 increases. Thereby, the contact area between the carbonated granular material 100 and water 22 increases, and the elution of Ca, Mg, K, and Na ions and the formation of carbonates are promoted.

[0020] Furthermore, the maximum particle size of the carbonated granular material 100 is more preferably 4.75 mm or less, and even more preferably 2.36 mm or less. Here, the maximum particle size of the carbonated granular material 100 means that when sieved using a sieve with a nominal mesh size as defined in JIS Z 8801-1:2019, the entire amount of the carbonated granular material 100 passes through a sieve with the same nominal mesh size as the maximum particle size.

[0021] As the maximum particle size of the carbonated granular material 100 decreases, the surface area of ​​the carbonated granular material 100 increases, thus promoting the elution of Ca, Mg, K, and Na ions. For this reason, there is no lower limit to the maximum particle size of the carbonated granular material 100. However, since it is difficult to crush the carbonated granular material 100 to a maximum particle size of less than 0.001 mm, it is preferable that the maximum particle size of the carbonated granular material 100 be 0.001 mm or larger.

[0022] In the method for producing the carbon oxide-containing granular material according to this embodiment, a carbonation accelerator 24 is brought into contact with the granular material to be carbonated 100 in the carbonation step to promote the carbonation reaction. In the method for producing the carbon oxide-containing granular material according to this embodiment, a liquid or solid substance containing one or more bacteria belonging to the genus Bacillus, family Bacillaceae, class Bacillus, family Clostridaceae, family Micrococcaceae, family Microbacterialaceae, and family Comamonasaceae is used as the carbonation accelerator 24. Examples of bacteria of the genus Bacillus include Bacillus subtilis, Bacillus mucilaginosus, Bacillus lentus, Bacillus simplex, Bacillus licheniformis, and Bacillus. furmus, Bacillus megaterium, Bacillus paralicheniformis, Bacillus altitudinis, Bacillus aryabhatta, Bacillus amyloliquefaciens, Bacillus One or more species of Alkalihalobacillus, Alkalihalobacillus miscanthi, Alkalihalobacillus marmarensis, Bacillus cohnii, Alkalihalobacillus pseudofirmus, and Alkalihalobacillus haloalkaliphilus may be used. As for the Bacillidae family, one or more species of Neobacillus drentensis and virgibacillus halodenitrificans may be used. As bacteria of the Bacillus class, one or more species of, for example, Sporosaricina pasteurii, Priestia megaterium, Priestia aryahattai, and Plananococcus sp. may be used. As bacteria of the Clostridaceae family, one or more species of, for example, Clostridium thermoalcaliphyllum and Alkaliphilus transvaalensis may be used. As bacteria of the Micrococcaceae family, for example, Arthrobacter koreensis may be used.As a bacterium of the Microbacterium family, for example, one or more species of Microcella indica and Microcella putealis may be used. As a bacterium of the Comamonadaceae family, for example, Caldimonas meghalayensis may be used.

[0023] These bacteria can be easily obtained by extraction from soil. Alternatively, bacteria can be purchased from designated national institutions and easily increased through cultivation. Therefore, by using bacteria as a carbonation accelerator, it becomes possible to carbonize the granular material to be carbonated 100 and produce a carbon oxide-containing granular material at a lower cost than conventional methods.

[0024] The bacterial concentration in the carbonation accelerator 24 is 1.0 × 10⁻⁶. ５ It is preferable that the CFU / g or higher concentration is used. This bacterial concentration is the number of bacteria (CFU) per gram of the carbonated granular material. The bacterial concentration of the carbonation accelerator 24 is 1.0 × 10⁻⁶. ５ When the CFU / g level is above this, sodium bicarbonate, calcium bicarbonate, potassium bicarbonate, sodium carbonate, calcium carbonate, and potassium carbonate are generated from the metal ions, thereby promoting the carbonation reaction of the granular material to be carbonated 100. In addition, the generation of carbonates from the metal ions by bacteria also promotes the elution of metal ions from the granular material to be carbonated 100.

[0025] On the other hand, the bacterial concentration of the carbonation accelerator 24 is 1.0 × 10 ５ If the CFU / g level falls below a certain value, the production of the above-mentioned substances becomes insufficient, and the elution of metal ions and the carbonation reaction do not proceed sufficiently, which is undesirable. The bacterial concentration of the carbonation accelerator 24 is 1.0 × 10⁻⁶. ８ It is more preferably CFU / g or higher, and 1.0 × 10 ９ It is even more preferable that the CFU / g or higher concentration is present. Since the carbonation of the carbonated granular material 100 is promoted as the bacterial concentration increases, there is no need to set an upper limit on the bacterial concentration; however, the effect will saturate, so the bacterial concentration should be 1.0 × 10⁻⁶. １２ It is preferable that the CFU / g level is 1 or less. The bacterial concentration of the carbonation accelerator 24 can be measured, for example, using a high-precision automatic colony counter BC-1000 manufactured by Keyence.

[0026] The type of bacteria contained in the carbonation accelerator 24 can be identified, for example, by analyzing the 16S rRNA gene in the bacterial DNA using 16S rRNA analysis with a next-generation sequencer, and then comparing the analysis results with a database. As a next-generation sequencer, for example, the Ion GeneStudio S5 system manufactured by Thermo Fisher Scientific can be used. The pH of the environment in which the bacteria are present is preferably 10.0 or higher. A pH of 10.0 or higher promotes the carbonation reaction.

[0027] The granular material to be carbonated 100 may be sprayed with water containing bacteria beforehand. By spraying with water containing bacteria beforehand, the granular material to be carbonated 100 becomes a granular material to be carbonated 100 containing the carbonation accelerator 24. In this way, if the granular material to be carbonated 100 contains the carbonation accelerator 24, it is not necessary to supply the carbonation accelerator 24 from the spray nozzle 14.

[0028] In the carbonation process, the total amount of water 22 sprayed onto the granular material to be carbonated 100 must be 1% by mass or more of the amount of water in the granular material to be carbonated 100. By spraying 1% by mass or more of water 22 onto the granular material to be carbonated 100, the water 22 can be brought into contact with the surface of the granular material to be carbonated 100, allowing the elution of metal ions and the carbonation reaction to proceed.

[0029] On the other hand, if the total amount of water 22 sprayed on the granular material to be carbonated is less than 1% by mass of the granular material to be carbonated 100, the contact between the granular material to be carbonated 100 and the water 22 will be insufficient, and the elution of metal ions will not proceed sufficiently, which is undesirable. The total amount of water 22 sprayed on the granular material to be carbonated 100 is preferably 5% by mass or more of the granular material to be carbonated 100, and more preferably 10% by mass or more of the granular material to be carbonated 100.

[0030] As the water 22 to be sprinkled on the carbonated granular material 100, it is preferable to use liquid water 22. As the liquid water 22 to be sprinkled on the carbonated granular material 100, fresh water, tap water, distilled water, ion-exchanged water, pure water, rainwater, well water, lake water, river water, industrial water, recycled water, salt water, brackish water, salt water, brine, concentrated seawater, seawater or hot spring water may be used. An example of the component composition of fresh water, seawater or hot spring water is shown in Table 2 below. As the liquid water 22 to be sprinkled on the carbonated granular material 100, it is preferable to use fresh water, tap water, industrial water or recycled water.

[0031]

[0032] The content of carbon dioxide contained in the carbon dioxide gas-containing gas 26 brought into contact with the carbonated granular material 100 is preferably 1% by volume or more of the carbonated granular material 100. By supplying 1% by volume or more of carbon dioxide to the carbonated granular material 100, the carbonated granular material 100 can be sufficiently carbonated. In addition, it is possible to suppress the water 22 supplied from the injection nozzle 14 from becoming strongly alkaline water and to suppress the generation of strongly alkaline water in the carbonation treatment.

[0033] As the carbon dioxide gas-containing gas 26 blown in from the gas ejection nozzle 16, a mixed gas of carbon dioxide gas and other gas species such as nitrogen, oxygen, carbon monoxide, water vapor, etc. may be used. The content of carbon dioxide gas in the carbon dioxide gas-containing gas 26 is preferably 0.03% by volume or more, and preferably 1% by volume or more. By using the carbon dioxide gas-containing gas 26 having a carbon dioxide gas content of 0.03% by volume or more, carbon dioxide necessary for the carbonation reaction can be supplied, and the carbonation of the carbonated granular material 100 can be promoted. The content of carbon dioxide in the carbon dioxide gas-containing gas 26 can be measured by analyzing the components of the carbon dioxide gas-containing gas 26.

[0034] The maximum temperature of the carbonated granular material 100 in the carbonation process needs to be above 0°C and below 100°C. If the maximum temperature of the carbonated granular material 100 is below 100°C, carbonation of the carbonated granular material 100 can be promoted using carbon dioxide dissolved in water 22. On the other hand, when the maximum temperature of the carbonated granular material 100 reaches 100°C or higher, the dissolved amount of carbon dioxide in water 22 significantly decreases, making it impossible to efficiently carbonate the carbonated granular material 100. Also, when the maximum temperature of the carbonated granular material 100 reaches 100°C or higher, the bacteria also die, making it impossible to efficiently carbonate the carbonated granular material 100. Therefore, the maximum temperature of the carbonated granular material 100 in the carbonation process needs to be below 100°C. The maximum temperature of the carbonated granular material 100 in the carbonation process is preferably 70°C or lower, more preferably 40°C or lower, and even more preferably 30°C or lower.

[0035] Also, when the maximum temperature of the carbonated granular material 100 reaches 0°C or lower, water 22 freezes, making it impossible to blow in the carbon dioxide gas-containing gas 26, and thus making it impossible to efficiently carbonate the carbonated granular material 100. Therefore, the maximum temperature of the carbonated granular material 100 in the carbonation process needs to be above 0°C. Also, the higher the maximum temperature of water 22 in the carbonation process, the more the carbonation reaction is promoted. When the maximum temperature of the carbonated granular material 100 is above 0°C and below 20°C, the improvement in carbonation efficiency due to the promotion of the carbonation reaction is greater than the decrease in carbonation efficiency due to the decrease in the dissolved amount of carbon dioxide. Therefore, the maximum temperature of the carbonated granular material 100 is preferably 10°C or higher, and more preferably 20°C or higher.

[0036] The maximum temperature of the carbonated granular material 100 in the carbonation treatment process is measured by the thermocouple 20. The thermocouple 20 is inserted into water 22. Since it is being stirred by the stirring blade 18, water 22 and the carbonated granular material 100 reach the same temperature. Therefore, by measuring the water temperature of water 22 during the carbonation process using the thermocouple 20, the maximum temperature of the carbonated granular material 100 in the carbonation process can be grasped.

[0037] It is preferable that the carbon dioxide-containing gas 26 is blown into the water 22 and the carbon dioxide-containing gas 26 is in contact with the granular material to be carbonated 100 for at least one minute. This allows for efficient production of carbon dioxide-containing granular material by bringing carbon dioxide into contact with the granular material to be carbonated 100. It is even more preferable that the carbon dioxide-containing gas 26 is blown into the water 22 and the carbon dioxide-containing gas 26 is in contact with the granular material to be carbonated 100 for at least five minutes.

[0038] As described above, in the method for producing a carbon dioxide-containing granular material according to this embodiment, the carbon dioxide-containing granular material is produced by bringing water 22, a carbon dioxide-containing gas 26, and a carbonation accelerator 24 containing bacteria into contact with the granular material to be carbonated 100. As mentioned above, bacteria that promote carbonation can be easily obtained and easily increased. Therefore, the method for producing a carbon dioxide-containing granular material according to this embodiment, which uses a carbonation accelerator 24 containing bacteria that promote carbonation, is a method that can produce a carbon dioxide-containing granular material at a lower cost than conventional methods. Thus, the method for producing a carbon dioxide-containing granular material according to this embodiment can produce a carbon dioxide-containing granular material while promoting the generation of carbon dioxide, so by implementing this manufacturing method, it becomes possible to produce a carbon dioxide-containing granular material with high carbonation efficiency.

[0039] The embodiments of the present invention are not limited to those described above and can be modified in various ways. In the example shown in Figure 1, a carbon dioxide gas-containing gas 26 is blown into water 22 containing the carbon dioxide gas-containing granular material 100 to be carbonated to produce a carbon oxide-containing granular material, but the invention is not limited to this. Instead of the carbon dioxide gas-containing gas 26, at least one of carbon dioxide gas-containing water, carbonate ion-containing water, and bicarbonate ion-containing water may be brought into contact with the carbon dioxide gas-containing granular material 100 to produce a carbon oxide-containing granular material. Note that carbon dioxide gas-containing water, carbonate ion-containing water, and bicarbonate ion-containing water are examples of liquid carbon dioxide gas-containing substances. Note that when using carbon dioxide gas-containing water, carbonate ion-containing water, and bicarbonate ion-containing water, water 22 may not be used.

[0040] Furthermore, instead of carbon dioxide gas-containing gas 26, dry ice may be immersed in water 22 to produce the carbon dioxide-containing granular material. Dry ice is an example of a solid carbon dioxide gas-containing substance. When using carbon dioxide gas-containing water, carbonate ion-containing water, bicarbonate ion-containing water, and dry ice, it is preferable to adjust the supply amounts of these so that the total amount of carbon dioxide contained in them is 1 volume percent or more of the carbon dioxide-containing granular material 100.

[0041] Alternatively, instead of blowing carbon dioxide gas-containing gas 26 into water 22 containing the carbonizable granular material 100, the carbon oxide-containing granular material may be produced by exposing the carbonizable granular material 100 containing water 22 to an atmosphere of carbon dioxide gas-containing gas 26. When using an open container, it is preferable to use air as the carbon dioxide gas-containing gas from a safety standpoint.

[0042] Thus, the carbonation process can be carried out using gaseous, liquid, and solid carbon dioxide-containing materials. Of these, gaseous carbon dioxide-containing materials are preferred because they are inexpensive and easy to handle.

[0043] Next, we will describe an example in which carbon oxide-containing granular material was produced using steelmaking slag (converter slag), waste concrete, or biomass incineration ash as the granular material to be carbonated. In this example, steelmaking slag or the like, which was crushed to a maximum particle size of 2 mm or less, was used as the granular material to be carbonated, and the carbonation process was carried out using the carbonation equipment 10 shown in Figure 1, with the stirring blade 18 rotating at 200 rpm to produce the carbon oxide-containing granular material. In this example, the alkaliphilic bacterium Alkalihalobacillus miscanthi was used. The production conditions and the carbonation efficiency of the carbon oxide-containing granular material in this example are shown in Tables 3 and 4 below.

[0044]

[0045]

[0046] The temperatures shown in the "Maximum Temperature of Carbonated Granular Material" column of Table 3 are the highest water temperatures measured by inserting a thermocouple into the water during the carbonation process. Both "Water Spray Amount" and "Carbonation Accelerator Content" in Table 3 represent the amount of water sprayed and the content of the carbonation accelerator relative to the granular material to be carbonated. "Concentration" is the amount per gram of granular material to be carbonated.

[0047] In the "Medium" column, "Gas + Liquid" refers to manufacturing examples where carbon dioxide-containing granular material is produced using carbon dioxide-containing water or carbon dioxide-containing water. "Solid + Liquid" refers to manufacturing examples where carbon dioxide-containing granular material is produced using dry ice-containing water. "Liquid" refers to manufacturing examples where carbon dioxide-containing granular material is produced using carbonate ion-containing water or bicarbonate ion-containing water, liquid carbon dioxide-containing water, or liquid carbon dioxide.

[0048] The values ​​shown in the "Carbonation Efficiency" column are calculated by dividing the carbon dioxide content (mass%) by the amount of carbon dioxide that can be generated (mass%) and multiplying the result by 100. The amount of carbon dioxide that can be generated is CaO, MgO, K ２ O and Na ２ This value was calculated from the O content. The higher this carbonation efficiency value, the more efficiently carbon dioxide-containing granular material can be produced.

[0049] As shown in Tables 3 and 4, Production Examples No. 1 to 3 are inventive examples in which carbon dioxide-containing granular material was produced by keeping the carbon dioxide content and water spraying amount the same for the granular material to be carbonated, while varying the content of the carbonation accelerator and the bacterial concentration. In Production Examples No. 1 to 3, the carbonation efficiency was 50.0% or higher. Among these, Production Example No. 1, which had the highest bacterial concentration, achieved the highest carbonation efficiency at 57.2%.

[0050] Manufacturing example No. 1 uses a carbonation accelerator content of 1.0% by mass, and a bacterial concentration of 1.0 × 10⁻⁶ relative to the granular material to be carbonated. ９ This is an example of an invention in which a carbon dioxide-containing granular material was manufactured at CFU / g. Manufacturing example No. 2 has a carbonation accelerator content of 1.0% by mass and a bacterial concentration of 1.0 × 10⁻⁶ relative to the granular material to be carbonized. ５This is an example of an invention in which a carbon dioxide-containing granular material was manufactured at CFU / g. Manufacturing example No. 3 has a carbonation accelerator content of 100.0% by mass and a bacterial concentration of 1.0 × 10⁻⁶ relative to the granular material to be carbonated. ５ This is an example of an invention in which a carbon dioxide-containing granular material was manufactured at CFU / g. Manufacturing example No. 16 uses a carbonation accelerator content of 1.0% by mass and a bacterial concentration of 1.0 × 10⁻⁶ relative to the carbonation-treated granular material. ４ This is an example of an invention in which a carbon dioxide-containing granular material was produced with a CFU / g ratio. Production example No. 21 is a comparative example in which a carbon dioxide-containing granular material was produced with a carbonation accelerator content of 0.0% by mass and a bacterial concentration of 0% by mass relative to the carbonized granular material.

[0051] Comparing manufacturing examples No. 1, 2, 3, 16, and 21, the carbonation efficiency of manufacturing example No. 1 was 57.2%, while that of manufacturing example No. 2 was 55.1%. The carbonation efficiency of manufacturing example No. 3 was 54.8%. The carbonation efficiency of manufacturing example No. 16 was 49.6%. The carbonation efficiency of manufacturing example No. 21 was 48.8%. Although the carbonation efficiency decreased with decreasing bacterial concentration in the carbonation accelerator, a carbonation efficiency of 50.0% or higher was ensured even in manufacturing examples No. 2 or No. 3. From these results, the bacterial concentration in the carbonation accelerator was 1.0 × 10⁻⁶ relative to the granular material to be carbonated. ５ It was confirmed that a CFU / g level of 1 or higher is preferable.

[0052] Production examples No. 4 to 9 are inventive examples in which carbon dioxide-containing granular material was produced by changing the type of carbon dioxide, while keeping the carbon dioxide content and water application rate in the carbon dioxide-containing granular material the same as in production example No. 1. Comparing production example No. 1 with production examples 4 to 9, the carbonation efficiency of production example No. 1 was 57.2%, while the carbonation efficiency of production examples No. 4 to 9 was 56.2% to 57.6%. Thus, since the carbonation efficiency was almost the same between production example No. 1 and production examples No. 4 to 9, it was confirmed that the type of carbon dioxide does not affect the carbonation efficiency of the carbon dioxide-containing granular material.

[0053] Manufacturing Example No. 10 is an inventive example in which carbon dioxide-containing granular material was produced by changing the maximum temperature of the granular material to be carbonated during the carbonation process, while keeping the carbon dioxide content and water application rate the same as in Manufacturing Example No. 1. Comparing Manufacturing Example No. 1 and Manufacturing Example No. 10, the carbonation efficiency of Manufacturing Example No. 1 was 57.2%, while in Manufacturing Example No. 10, where the maximum temperature of the granular material to be carbonated during the carbonation process was increased to 90°C, the carbonation efficiency decreased to 50.1%. When the water temperature increases during the carbonation process, the amount of dissolved carbon dioxide in the water decreases. Therefore, it is thought that the carbonation efficiency decreased as the maximum temperature of the granular material to be carbonated increased.

[0054] Manufacturing Example No. 19 is a comparative example in which carbon dioxide-containing granular material was produced by keeping the carbon dioxide content and water spraying amount in the granular material to be carbonated the same as in Manufacturing Example No. 1, but by setting the maximum temperature of the granular material to be carbonated in the carbonation process to 0°C. Comparing Manufacturing Example No. 1 and Manufacturing Example No. 19, the carbonation efficiency of Manufacturing Example No. 1 was 57.2%, while the carbonation efficiency of Manufacturing Example No. 19 was 0.0%. It is thought that when the maximum temperature of the granular material to be carbonated falls below 0°C in the carbonation process, the water freezes and carbon dioxide gas cannot be injected, thereby preventing the carbonation of the carbon dioxide-containing granular material from progressing.

[0055] Production Example No. 20 is a comparative example in which carbon dioxide-containing granular material was produced by keeping the carbon dioxide content and water spraying amount in the granular material to be carbonated the same as in Production Example No. 1, but by raising the maximum temperature of the granular material to be carbonated in the carbonation process to 100°C. Comparing Production Example No. 1 and Production Example No. 20, the carbonation efficiency of Production Example No. 1 was 57.2%, while the carbonation efficiency of Production Example No. 20 was 2.0%.

[0056] In the carbonation process, when the maximum temperature of the granular material to be carbonated exceeds 100°C, the amount of carbon dioxide dissolved in the water decreases significantly, which is thought to have reduced the carbonation efficiency. Furthermore, when the maximum temperature of the granular material to be carbonated exceeds 100°C, the bacteria in the carbonation accelerator are killed, which is thought to have reduced the carbonation-promoting effect of these bacteria. From these results, it was confirmed that by contacting the granular material to be carbonated, whose maximum temperature is between 0°C and 100°C, with a carbon dioxide-containing substance in the carbonation process, it is possible to produce carbon oxide-containing granular material with high carbonation efficiency.

[0057] Manufacturing Examples No. 11 and 12 are inventive examples in which carbon dioxide-containing granular material was produced by changing the type of carbon dioxide-containing granular material, while keeping the carbon dioxide content and water application amount in the carbon dioxide-containing granular material the same as in Manufacturing Example No. 1. Comparing Manufacturing Example No. 1 with Manufacturing Examples No. 11 and 12, the carbon dioxide content in Manufacturing Example No. 1 was 37.2% by mass, while the carbon dioxide content in Manufacturing Examples No. 11 and 12, which used different types of carbon dioxide-containing granular material, was 40.0% by mass or more. Compared to converter slag, waste concrete and biomass incineration ash contain not only CaO but also K ２ O and Na ２ It also contains a large amount of oxygen (O). For this reason, the amount of carbon oxide that could be generated was greater in production examples No. 11 and 12, which used waste concrete and biomass incineration ash, than in production example No. 1, which used converter slag as the granular material to be carbonated. As a result, the carbon oxide content also increased.

[0058] Production Example No. 13 is an inventive example in which the carbon dioxide content and water spraying amount in the granular material to be carbonated were the same as in Production Example No. 1, but bacteria were added to the granular material to be carbonated before processing to produce a carbon dioxide-containing granular material. Comparing Production Example No. 1 and Production Example No. 13, the carbonation efficiency of Production Example No. 1 was 57.2%, while the carbonation efficiency of Production Example No. 13 was 56.8%. Thus, since the carbonation efficiency of Production Example No. 1 and Production Example No. 13 were almost the same, it was confirmed that bacteria may be added to the granular material to be carbonated before processing, or may be added to the granular material to be carbonated during processing.

[0059] Production Example No. 14 is an inventive example in which carbon dioxide-containing granular material was produced by adding bacteria before and during the carbon dioxide-containing granular material treatment process, while keeping the carbon dioxide content and water application rate the same as in Production Example No. 1. Comparing Production Example No. 1 and Production Example No. 14, the carbonation efficiency of Production Example No. 1 was 57.2%, while the carbonation efficiency of Production Example No. 14 was 58.4%. From these results and the results of Production Example No. 14, it was confirmed that a higher concentration of bacteria added in the carbonation process is preferable.

[0060] Manufacturing Example No. 15 is an inventive example in which carbon dioxide-containing granular material was produced using the same carbon dioxide content as Manufacturing Example No. 1, but with a water spraying amount of 1% by mass in the carbonation process. Comparing Manufacturing Example No. 1 and Manufacturing Example No. 15, the carbonation efficiency of Manufacturing Example No. 1 was 57.2%, and the carbonation efficiency of Manufacturing Example No. 15 was also 57.2%. From these results, it was confirmed that the granular material can be carbonized if the total amount of water contacted in the carbonation process is 1% by mass or more relative to the granular material.

[0061] Production examples No. 17 and 18 are comparative examples in which carbon oxide-containing granular material was produced without contact with carbon dioxide. Comparing production example No. 1 with production examples No. 17 and 18, the carbonation efficiency of production example No. 1 was 57.2%, while the carbonation efficiency of production examples No. 17 and 18 was 0.0%. From these results, it was confirmed that in the carbonation process, it is necessary to contact the granular material to be carbonated with a carbon dioxide-containing substance, carbonate ion-containing water, or bicarbonate ion-containing water, and that this allows for the production of carbon oxide-containing granular material with high carbonation efficiency.

[0062] 10 Carbonation equipment 12 Container 14 Injection nozzle 16 Gas ejection nozzle 18 Agitator blade 20 Thermocouple 22 Water 24 Carbonation accelerator 26 Carbon dioxide gas-containing gas 100 Granular material to be carbonated

Claims

1. A method for producing a carbon dioxide-containing granular material, comprising a carbonation step of contacting a granular material to be carbonated, having a maximum temperature greater than 0°C and less than 100°C, with water, a carbonation accelerator, and at least one of a carbon dioxide-containing substance, carbonate ion-containing water, and bicarbonate ion-containing water, or a carbonation accelerator and at least one of carbon dioxide-containing water, carbonate ion-containing water, and bicarbonate ion-containing water, wherein the total amount of water contacted in the carbonation step is 1% by mass or more of the granular material to be carbonated, and the carbonation accelerator contains bacteria, wherein the bacteria are at least one of the genus Bacillus, family Bacillaceae, class Bacillus, family Clostridaceae, family Micrococcaceae, family Microbacterialaceae, and family Comamonadaceae.

2. The bacterial concentration of the carbonation accelerator is 1.0 × 10⁻⁶ ５ A method for producing a carbon oxide-containing granular material according to claim 1, wherein the CFU / g is 1 or higher.

3. A method for producing a carbon oxide-containing granular material according to claim 1 or claim 2, wherein the granular material to be carbonated and / or water includes the carbonation accelerator.

4. The method for producing a carbon oxide-containing granular material according to any one of claims 1 to 3, wherein the carbon dioxide-containing substance is a gas.

5. A method for producing a carbon oxide-containing granular material according to any one of claims 1 to 4, wherein the particle size of the carbonated granular material satisfies any of the following: the content of particles with a particle size of 0 to 75 μm exceeds 25% by mass, the content of particles with a particle size of 0 to 425 μm exceeds 30% by mass, the content of particles with a particle size of 0 to 2.36 mm exceeds 50% by mass, the content of particles with a particle size of 0 to 4.75 mm exceeds 65% by mass, and the content of particles with a particle size of 0 to 13.2 mm exceeds 85% by mass.

6. The method for producing a carbon oxide-containing granular material according to any one of claims 1 to 5, wherein the granular material to be carbonated is steelmaking slag.

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