Granulation system and method for producing granulated material

Abstract

To provide a granulation system which granulates a granulation target material containing at least one of an alkali metal or an alkaline earth metal, as well as a production method for granulated materials.SOLUTION: The present invention provides a granulation system which granulates a granulation target material 40 containing at least one of an alkali metal or an alkaline earth metal, where the granulation system is equipped with a first solution addition device 3 for adding a carbon dioxide-dissolved solution 51 to the granulation target material 40.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a granulation system for granulating an object containing at least one of an alkali metal and an alkaline earth metal, and a method for producing a granulated product. [Background technology]

[0002] In recent years, in order to realize a sustainable society, active efforts have been made to effectively utilize by-products generated in the manufacturing process of various products, reduce waste, and recycle resources. In addition, active efforts are being made to reduce carbon dioxide emissions.

[0003] As an example of recycling, it is known to recover and recycle coarse aggregate from the residue (by-product) remaining after the production of ready-mix concrete, etc. Patent Document 1 describes ready-mix concrete using an aqueous medium with a dissolved calcium ion concentration of 700 to 1000 ppm as a raw material, which is obtained by injecting gas containing carbon dioxide while stirring concrete recovery water (washing wastewater from ready-mix concrete production equipment, separated recovery water from unused concrete, etc.).

[0004] There are also efforts to recycle fly ash generated by incinerators and incineration ash (a by-product, hereinafter referred to as "biomass ash") discharged from wood biomass power generation as aggregate for cement. Patent Document 2 describes a method in which by-products such as fly ash are reacted with carbon dioxide to produce calcium carbonate, which is then used as a cement admixture.

[0005] Furthermore, there are efforts to use slag (a by-product) generated in the steel manufacturing process as roadbed material or fertilizer. Patent Document 3 describes a method for producing a granulated material (carbonate solidified body) by contacting a CaO-containing granulated material such as slag generated in the steel manufacturing process with carbon dioxide gas.

[0006] In both recycling processes, not only are by-products effectively utilized, but carbon dioxide emissions are also reduced by absorbing and fixing the carbon dioxide in the resource as calcium carbonate. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2016-79054 A [Patent Document 2] JP 2021-155271 A [Patent Document 3] JP 2006-188368 A Summary of the Invention [Problem to be solved by the invention]

[0008] The methods for producing granulated materials in Patent Documents 1 to 3 simply involve contacting a by-product with carbon dioxide gas, and therefore there is room for improvement in terms of efficient production of granulated materials. In particular, the method for producing granulated materials in Patent Document 3 involves blowing carbon dioxide gas into the material to be granulated during granulation to obtain a carbonated solidified body, and therefore the reaction between Ca contained in the material to be granulated and carbon dioxide gas is insufficient.

[0009] The present invention aims to further effectively utilize by-products and reduce carbon dioxide emissions, and has as its objective the effective utilization of wastewater, sludge, and dust generated in the concrete recycling process, as well as fly ash generated in incinerators, etc. [Means for solving the problem]

[0010] The characteristic configuration of the granulation system of the present invention is that it is a granulation system that granulates a granulation object containing at least one of an alkali metal and an alkaline earth metal, and is equipped with a first solution addition device that adds a solution in which carbon dioxide is dissolved to the granulation object.

[0011] In this configuration, the granulation system for granulating the material to be granulated is provided with a first solution adding device for adding a solution in which carbon dioxide is dissolved, so that the solution in which carbon dioxide is dissolved can be added to the material to be granulated to perform granulation. The material to be granulated contains at least one of an alkali metal and an alkaline earth metal, and reacts with carbonate ions derived from carbon dioxide contained in the solution to generate carbonate. Therefore, a process for generating carbonate while granulating (hereinafter also referred to as carbonation process) can be performed. That is, since the material to be granulated can be carbonated in the granulation process without carbonating it in advance, there is no need to provide a carbonation treatment device in the granulation system, and the manufacturing equipment can be simplified. Furthermore, since carbon dioxide is dissolved in the solution, the contact area between the material to be granulated and the carbonate ions is increased, and the carbonation process can be performed more efficiently.

[0012] A further characteristic configuration of the present invention is that it comprises a kneader for kneading the material to be granulated, and a granulator for granulating the kneaded material produced in the kneader, and the first solution addition device is provided in at least one of the kneader and the granulator.

[0013] In this configuration, by providing the kneader with the first solution adding device, it is possible to uniformly mix the granulation material and the solution in which carbon dioxide is dissolved, so that the carbonation treatment can be performed more efficiently. In addition, by providing the granulator with the first solution adding device, it is possible to perform the carbonation treatment while adjusting the moisture content suitable for granulation. Furthermore, by providing both the kneader and the granulator with the first solution adding device, it is possible to perform the carbonation treatment in the granulator even on the granulation material that was not carbonated in the kneader, so that the amount of granulation material containing unreacted alkali metals and / or alkaline earth metals can be reduced. This improves the quality of the granulated material. In particular, when the granulated material is used as aggregate for concrete, pop-out caused by the granulated material can be prevented.

[0014] A further characteristic feature of the present invention is that it includes a carbonation device that carbonates the granulation object by contacting the granulation object with a gas containing carbon dioxide or the solution before or during kneading of the granulation object.

[0015] In this configuration, the material to be granulated is carbonated before being kneaded and granulated, and then carbonation is performed in the granulation system, thereby making it possible to reduce the amount of material to be granulated that contains unreacted alkali metals and / or alkaline earth metals. This makes it possible to further improve the quality of the granulated material and reliably prevent pop-out. In addition, if carbonation is performed during kneading, the kneader and carbonation device can be used together to perform carbonation efficiently.

[0016] A further characteristic feature of the present invention is that the gas or the solution is produced using a gas generated by a thermal treatment or a biological treatment.

[0017] Gas generated in thermal treatment facilities and biological treatment facilities contains carbon dioxide. In particular, it is not preferable to directly discharge exhaust gas generated by incineration, which is a thermal treatment, from the viewpoint of efforts toward a carbon-free society. Therefore, by using exhaust gas for carbonation treatment as in this configuration, it is possible to effectively utilize the carbon dioxide contained in the exhaust gas and reduce the amount of carbon dioxide emissions. In addition, since the carbon dioxide contained in the gas generated in a methane fermentation facility, which is a biological treatment facility, is highly concentrated at about 25% to 45%, carbonation treatment can be efficiently performed by using this.

[0018] A further characteristic feature of the present invention is that the solution is obtained by dissolving carbon dioxide in recovered water generated in a concrete washing process or a concrete regeneration process.

[0019] According to this configuration, the recovered water generated in the concrete washing process and regeneration process can be effectively used for the carbonation process without being discarded. In addition, since such recovered water contains Ca, the Ca reacts with carbonate ions to generate calcium carbonate, which can absorb and fix carbon dioxide. Furthermore, by generating calcium hydrogen carbonate instead of generating calcium carbonate and transporting it to the granulation system in the form of a solution, there is no need for equipment or storage space for collecting the generated calcium carbonate. This makes it possible to simplify the granulation system and efficiently obtain granulated material.

[0020] A further characteristic feature of the present invention is that the solution is obtained by dissolving carbon dioxide in recovered water generated in a sludge or soil washing process.

[0021] According to this configuration, recovered water generated in the sludge or soil washing process can be effectively used for carbonation treatment without being discarded. Since such recovered water contains alkali metals and alkaline earth metals, these components react with carbonate ions to generate carbonates, which can absorb and fix carbon dioxide.

[0022] A further characteristic feature of the present invention is that the granulation object includes recycled aggregate, sludge, or dust generated in a washing process or a recycling process of the concrete.

[0023] According to this configuration, recycled aggregates generated in the concrete washing and recycling processes can be effectively utilized, and sludge or dust can be recycled through carbonation treatment without being disposed of. Furthermore, the alkali metals or alkaline earth metals contained in the sludge or dust react with carbon dioxide to generate carbonates, thereby obtaining a granulated material and absorbing and fixing carbon dioxide.

[0024] A further characteristic feature of the present invention is that the granulation object includes biomass ash, fly ash, or slag.

[0025] This configuration makes it possible to effectively utilize biomass ash, fly ash generated in incineration facilities, and slag generated in steel manufacturing processes. Since these all contain alkali metals and alkaline earth metals, carbonation treatment produces carbonates that can absorb and fix carbon dioxide.

[0026] A further characteristic configuration of the present invention is that it includes a dryer that dries the granulated material produced by the granulator, and a second solution adding device that adds the solution to the dried granulated material.

[0027] According to this configuration, the desired strength can be obtained by drying the granulated material. When a solution in which carbon dioxide is dissolved is added to the surface of the granulated material after the granulated material is dried as in this configuration, carbonate is generated in the surface layer of the granulated material. When carbonate is generated in the surface layer of the granulated material, the surface layer of the granulated material becomes dense, and the quality of the granulated material can be stabilized.

[0028] The characteristic configuration of the method for producing a granulated material according to the present invention includes a kneading process for kneading a granulation target material containing at least one of an alkali metal and an alkaline earth metal, and a granulation process for granulating the kneaded material produced by the kneading process, and is characterized in that a solution in which carbon dioxide is dissolved is added in at least one of the kneading process and the granulation process.

[0029] In this method, by adding a solution containing dissolved carbon dioxide in the kneading process, it is possible to stir the granulation object and the solution containing dissolved carbon dioxide, so that the carbonate ions in the solution react with the alkali metal and / or alkaline earth metal contained in the granulation object to generate carbonate. Therefore, even if a process for carbonating the granulation object in advance is not provided, the carbonation process can be performed in the kneading process. In addition, by adding a solution containing dissolved carbon dioxide in the granulation process, the carbonation process can be performed while adjusting the moisture content suitable for granulation. Furthermore, by adding a solution containing dissolved carbon dioxide in both the kneading process and the granulation process, it is possible to perform the carbonation process in the granulation process for the granulation object that was not carbonated in the kneading process, so that the amount of granulation object containing unreacted alkali metal and / or alkaline earth metal can be reduced. This makes it possible to prevent pop-out caused by the granulation when the granulation is used as an aggregate for concrete.

[0030] A further characteristic feature of the present invention is that a pre-granulation carbonation process is carried out before the kneading process, in which the material to be granulated is carbonated by contacting the material with a gas containing carbon dioxide or the solution.

[0031] According to this method, the material to be granulated is carbonated before being kneaded and granulated, and then carbonated again in the kneading step or granulation step, thereby reducing the amount of the material to be granulated that contains unreacted alkali metals and alkaline earth metals, thereby improving the quality of the granulated material and reliably preventing pop-out.

[0032] A further characteristic configuration of the present invention is that it includes a drying process for drying the granulated material produced by the granulation process, and a post-granulation carbonation process for carbonating the granulated material by adding the solution to the granulated material dried by the drying process.

[0033] According to this method, the granules can be dried in the drying step to obtain the desired strength. When a solution containing dissolved carbon dioxide is added to the surface of the granules after the granules are dried as in this method, carbonate is generated in the surface layer of the granules. When carbonate is generated in the surface layer of the granules, the surface layer of the granules becomes dense, and the quality of the granules can be stabilized. [Brief description of the drawings]

[0034] [Figure 1] FIG. 1 is a schematic diagram showing the device configuration of a granulation system according to a first embodiment. [Diagram 2] FIG. 4 is a schematic diagram showing the device configuration of a granulation system according to a second embodiment. [Diagram 3] FIG. 11 is a schematic diagram showing the device configuration of a granulation system according to a third embodiment. [Figure 4] FIG. 13 is a schematic diagram showing the device configuration of a granulation system according to a fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] Hereinafter, an embodiment of the granulation system and the method for producing granulated material according to the present invention will be described with reference to the drawings. In this embodiment, a method for producing granulated material using granulation material generated from an incineration facility and recovered water generated in a concrete recycling process will be described. However, the present invention is not limited to the following embodiment, and various modifications are possible within the scope of the gist of the present invention.

[0036] [First embodiment] Fig. 1 is a schematic diagram of a granulation system 1 according to a first embodiment. The granulation system 1 includes a granulation device 2 that granulates the material to be granulated 40 generated from an incineration facility 4. The granulation device 2 has a first solution adding device 3 that adds a solution 51 in which carbon dioxide is dissolved. The material to be granulated 40 and the solution 51 in which carbon dioxide is dissolved are mixed and granulated in the granulation device 2, whereby a granulated material 10 that has been subjected to a carbonation treatment can be obtained.

[0037] The granulation object 40 is incineration ash such as bottom ash and fly ash. In addition, it is not limited to those generated from the incineration facility 4, but may be incineration ash from wood biomass power generation, slag generated in the steel manufacturing process, etc. Furthermore, recycled aggregate, sludge, or dust generated in the concrete recycling process 5 may be the granulation object 40, or a mixture of these. These by-products contain Ca, Mg, and K. In addition, the granulation object 40 is not limited to these, and any composition is acceptable as long as it is intended for granulation.

[0038] From the incineration facility 4, exhaust gas 41 containing carbon dioxide is discharged together with the granulation target material 40. By injecting this exhaust gas 41 into the recovered water 50 generated in the concrete recycling process 5, a solution 51 containing dissolved carbon dioxide can be obtained. Gas generated by biological treatment may be injected into the recovered water 50 instead of the exhaust gas 41. Also, air may be injected into the recovered water 50 regardless of the source of the gas as long as it contains carbon dioxide. The exhaust gas 41 may be cooled when it is discharged from the incinerator, and may be subjected to a process for neutralizing acid gas contained in the exhaust gas 41.

[0039] The concrete recycling process 5 is a process for removing foreign matter such as reinforcing bars from demolished concrete to obtain recycled aggregate, and in this process, recovered water 50 is generated. In addition, the recovered water 50 may be washing wastewater generated when washing ready-mix concrete manufacturing equipment, sludge water containing solids such as cement, or supernatant water obtained by removing solids from sludge water. Since these contain Ca, when exhaust gas 41 is blown into the recovered water 50, the reactions shown in formulas (1) to (5) occur to generate carbonates. That is, as shown in formula (1), carbon dioxide contained in the exhaust gas 41 dissolves in the recovered water 50 to generate carbonic acid, and as shown in formulas (2) and (3), carbonate ions or bicarbonate ions are generated by ionization of carbonic acid. When the pH of the solution 51 is high, poorly water-soluble calcium carbonate is generated as shown in formula (4), and when the pH is low, water-soluble calcium bicarbonate is generated as shown in formula (5). Therefore, the more exhaust gas 41 is blown in, the lower the pH of the recovered water 50 becomes, and the Ca contained in the recovered water 50 exists as calcium bicarbonate. In this manner, carbon dioxide is dissolved in the recovered water 50 and fixed as calcium hydrogen carbonate to obtain a solution 51. CO2 + H2O → H2CO3 (1) H2CO3→H + +HCO3 - (2) HCO3 - →H + +CO3 2- (3) Ca 2+ +CO3 2- →CaCO3···(4) Ca 2+ +2HCO3 - →Ca(HCO3)2···(5)

[0040] When the pH of the solution 51 rises, calcium carbonate is generated according to formula (4) and a precipitate is generated. In other words, if the pH of the solution 51 is adjusted so as to maintain the equilibrium of formula (5), calcium carbonate will not be generated. That is, by adjusting the pH of the solution 51, the location where calcium carbonate is generated can be arbitrarily determined. Therefore, even if the exhaust gas 41 is blown into the recovered water 50 to perform carbonation treatment, calcium carbonate that becomes a precipitate is not generated, and it can be transported to the granulation device 2 as a liquid in which carbon dioxide is dissolved. In other words, since there is no need to collect calcium carbonate that is generated as a precipitate in the process of blowing the exhaust gas 41 into the recovered water 50 and transporting it to the granulation device 2, a filtration device or the like is not required, and it is possible to simplify the granulation system 1 and reduce the required facility area. And, by generating calcium carbonate from the solution 51 in the granulation device 2, this calcium carbonate can also be used as a granulation target. Therefore, it is possible to obtain a granulated material 10 in which the granulation target 40 and calcium carbonate are mixed, and carbon dioxide can be absorbed and fixed in the granulation device 2.

[0041] The solution 51 in which carbon dioxide is dissolved is added to the granulation device 2 by the first solution adding device 3. The first solution adding device 3 may be of any type as long as it can add a solution to the granulation device 2. In addition, the device may be equipped with a flow rate adjustment mechanism that measures the weight of the object 40 to be granulated and calculates the amount to be added. Granulation can be performed using techniques such as a tumbling granulation method, an agitation granulation method, a pellet method, a spray granulation method, and a spray fluidized bed method. The granulation device 2 can be a known granulation device such as an agitation granulator or an extrusion granulator.

[0042] The solution 51 in which carbon dioxide is dissolved also reacts with alkali metals such as K and alkaline earth metals such as Ca contained in the granulation target 40 to generate carbonates. Therefore, the granulation target 40 can be carbonated in the granulation device 2, so there is no need to pre-carbonate the granulation target 40, and the granulation system 1 can be simplified and the number of facilities can be reduced. In addition, the granulation device 2 uniformly mixes the solution 51 added by the first solution adding device 3 with the granulation target 40, so that the solution 51 uniformly contacts the surface of the granulation target 40. Since carbon dioxide is dissolved in the solution 51 and exists as carbonate ions, the reaction of formula (4) occurs particularly at the contact surface between the granulation target 40 and the solution 51, and calcium carbonate is generated. According to this embodiment, it is possible to increase the contact area between the granulation target 40 and the solution 51, so that the surface area where the carbonation reaction occurs in the granulation target 40 can be increased. Therefore, compared to the case where a gas containing carbon dioxide is introduced when the solution in which carbon dioxide is not dissolved and the material to be granulated 40 are mixed and granulated, it is possible to obtain a granulated material 10 in which the carbonation process has been performed to the inside of the granulated material 10. Furthermore, since the carbonation process and granulation can be performed at the same time, the material to be granulated 40 and the generated calcium carbonate can be mixed together to efficiently obtain the granulated material 10. Note that in order to further promote carbonation, a gas containing carbon dioxide may be further introduced into the granulation device 2 in addition to the addition of the solution 51.

[0043] Instead of the recovered water 50, tap water or industrial wastewater may be used, and Ca may not be contained. Even in this case, a solution 51 in which carbon dioxide is dissolved can be prepared by blowing in carbon dioxide. The pH of this solution 51 is preferably in the range of 7.5 to 11. When the pH is 7.5, the abundance ratio of hydrogen carbonate ions is maximum, and when the pH is 11, the abundance ratio of carbonate ions is maximum. Therefore, the pH of the solution 51 is particularly preferably 10 to 11, at which calcium carbonate is easily generated. The granulation target 40 can be carbonated using this solution 51. The carbonation mechanism is the same as described above. Even when the granulation target 40 does not contain Ca, the granulation target 40 derived from a by-product contains Na and K. Carbon dioxide can also be absorbed and fixed by carbonation of these components.

[0044] Second Embodiment Next, a granulation system 1 according to a second embodiment will be described with reference to Fig. 2. In this embodiment, the granulation device 2 is divided into a mixer 20 and a granulator 21, and the first solution adding device 3 is provided in both the mixer 20 and the granulator 21. Since the other configurations are the same as those in the first embodiment, detailed descriptions of the same configurations as those in the first embodiment will be omitted.

[0045] In this embodiment, the granulation device 2 is composed of a kneader 20 and a granulator 21, both of which are equipped with a first solution adding device 3. The first solution adding device 3 adds a solution 51 obtained by blowing exhaust gas 41 generated in an incineration facility 4 into recovered water 50 generated in a concrete recycling process 5 to the kneader 20 and the granulator 21. The kneader 20 can be of any type as long as it can mix and stir the granulation object 40 and the solution 51, and for example, a twin-shaft mixer or the like can be used. In the kneader 20, the solution 51 in which carbon dioxide is dissolved is added from the first solution adding device 3 to the granulation object 40, and the solution 51 and the granulation object 40 are mixed and stirred. At this time, a binding agent such as a binder may be added. By stirring, the granulation object 40 obtains moisture suitable for granulation, and the binding agent is uniformly distributed in the granulation object 40. Then, calcium carbonate and the like are produced by contacting the solution 51 in which carbon dioxide is dissolved with the material to be granulated 40, and the material to be granulated 40 is carbonated. Calcium carbonate is also produced from the solution 51.

[0046] The granulation target 40 and the generated calcium carbonate, etc., which have been mixed, stirred, and carbonated in the kneader 20, are granulated in the granulator 21. The granulator 21 may be of any type as long as it can granulate the granulation target 40, and may be, for example, an extrusion-type granulator. The granulation target 40 has been carbonated in the kneader 20, but since it is difficult to completely carbonate the target, it may contain unreacted Ca, etc. In the granulator 21, a solution 51 in which carbon dioxide is dissolved is added to the granulation target 40 by the first solution adding device 3, and the carbonate ions in the solution 51 are reacted with the unreacted Ca, etc., thereby reducing the amount of unreacted Ca, etc. As a result, the granulation target 10 that has been reliably carbonated can be obtained, and the quality of the granulation target 10 can be improved. In addition, the moisture can be adjusted in the granulator 21 so that the moisture value is suitable for granulation.

[0047] Third Embodiment Next, a granulation system 1 according to a third embodiment will be described with reference to Fig. 3. In this embodiment, the granulation system 1 includes a carbonation device 6 that performs a carbonation process on the granulation target 40 before it is fed into the kneader 20. A solution 51 in which exhaust gas 41 generated in the incineration facility 4 is blown into recovered water 50 generated in the concrete recycling process 5 is fed into the carbonation device 6. The other configurations are the same as those in the second embodiment, so detailed descriptions of the same configurations as those in the second embodiment will be omitted.

[0048] The granulation target 40 is charged into the kneader 20 after being carbonated in the carbonation device 6. The granulation target 40 is carbonated in the carbonation device 6, but it is difficult to completely carbonate it, and it may contain unreacted Ca or the like. Therefore, in the kneader 20 and the granulator 21, the granulation target 40 and the solution 51 are carbonated in the same manner as in the second embodiment, so that the granulation target 10 that has been carbonated more reliably can be obtained. The carbonation device 6 can be a known one. The granulation target 40 after the carbonation may be separated from the solution 51 and then dried before being charged into the kneader 20, or may be used without being dried. The carbonation may be performed by contacting the granulation target 40 with a gas containing carbon dioxide.

[0049] [Fourth embodiment] Next, a granulation system 1 according to a fourth embodiment will be described with reference to Fig. 4. In this embodiment, the granulation system 1 includes a dryer 7 for drying the granulated material 10 granulated by the granulator 21, and a second solution adding device 8 for adding a solution 51 in which carbon dioxide is dissolved to the granulated material 10 after drying. The solution 51 in which carbon dioxide is dissolved is obtained by injecting exhaust gas 41 generated in the incineration facility 4 into recovered water 50 generated in the concrete recycling process 5. Since the other configurations are the same as those in the third embodiment, detailed description of the same configurations as those in the third embodiment will be omitted.

[0050] The dryer 7 may be of any type as long as it can dry the granulated material 10, and may be, for example, a heating furnace or a rotary kiln. These may be equipped with a mechanism for adjusting the drying temperature and drying time. In addition, the dryer may be one that utilizes exhaust heat generated in the incineration facility 4, or one that cures the granulated material 10. The granulated material 10 dried in the dryer 7 is stored, for example, in a yard. The second solution adding device 8 may be provided in a storage location for the granulated material 10, or may be provided on a conveyor that transports the granulated material 10 in the yard. The second solution adding device 8 may be the same as the first solution adding device 3, but it is preferable that the second solution adding device 8 is a spray type that sprays the solution 51 onto the granulated material 10.

[0051] The solution 51 is sprayed onto the surface of the granulated material 10 by the second solution adding device 8. Since the solution 51 contains Ca and carbonate ions, the Ca etc. contained in the solution 51 or the Ca present on the surface of the granulated material 10 reacts with the carbonate ions to produce carbonates on the surface layer of the granulated material 10. This makes the surface layer of the granulated material 10 denser, making it difficult for carbonation to occur inside the granulated material 10, and making it possible to stabilize the quality of the granulated material 10. The granulated material 10 may be repeatedly fed into the dryer 7 to be dried, and the solution 51 may be repeatedly sprayed onto the surface of the granulated material 10 by the second solution adding device 8.

[0052] Next, a method for producing the granulated material 10 in the second embodiment will be described with reference to FIG.

[0053] First, exhaust gas 41 generated in the incineration facility 4 is blown into recovered water 50 generated in the concrete recycling process 5 to generate a solution 51 in which carbon dioxide is dissolved. Next, the material to be granulated 40 is put into the kneader 20, and the solution 51 is added by the first solution adding device 3 to perform a kneading process in which the material to be granulated 40 and the solution 51 are mixed uniformly. The kneaded material after the kneading process is received in a hopper or conveyor and transported to the granulator 21, where the granulator 21 performs a granulation process to obtain a granulated material 10 (second embodiment). In the granulation process, the solution 51 may be added by the first solution adding device 3 so that the kneaded material has a moisture content suitable for granulation. According to this manufacturing method, a granulated material 10 in which carbon dioxide is absorbed and fixed using by-products as raw materials is obtained, and the manufacturing equipment can be simplified to efficiently manufacture the granulated material 10. Note that the manufacturing method of the granulated material 10 in the first embodiment does not include the kneading process, so a description thereof will be omitted.

[0054] Next, a method for producing the granulated material 10 in the third embodiment will be described with reference to FIG.

[0055] First, exhaust gas 41 generated in the incineration facility 4 is blown into recovered water 50 generated in the concrete recycling process 5 to prepare a solution 51 in which carbon dioxide is dissolved. Next, a pre-granulation carbonation process is carried out in which the granulation target 40 is brought into contact with the solution 51 to perform carbonation. The pre-granulation carbonation process can be carried out in a known carbonation device 6.

[0056] Next, the carbonated material 40 to be granulated is charged into the kneader 20, and the solution 51 is added by the first solution adding device 3 to perform a kneading step in which the material 40 to be granulated and the solution 51 are uniformly mixed. After kneading is completed, the kneaded material is received in a hopper or conveyor and transported to the granulator 21, where a granulation step is performed to obtain a granulated material 10. According to this production method, the material 40 to be granulated is carbonated multiple times to obtain a granulated material 10 with stable quality, and carbon dioxide can be absorbed and fixed.

[0057] Further, a method for producing the granulated material 10 in the fourth embodiment will be described with reference to FIG.

[0058] First, exhaust gas 41 generated in the incineration facility 4 is blown into recovered water 50 generated in the concrete recycling process 5 to create a solution 51 with dissolved carbon dioxide. Next, a pre-granulation carbonation process is performed in which the granulation target 40 is brought into contact with the solution 51 to carbonate it. The carbonated granulation target 40 is fed into the kneader 20, and the solution 51 is added by the first solution adding device 3 to perform a kneading process in which the granulation target 40 and the solution 51 are uniformly mixed. After kneading, the kneaded material is received in a hopper or conveyor and transported to the granulator 21, where the granulation process is performed to obtain granulated material 10.

[0059] Next, a drying step is carried out to dry the obtained granulated material 10. The drying step may be carried out in a heating furnace or by curing. Finally, a post-granulation carbonation step is carried out to carbonate the surface of the granulated material 10 by adding a solution 51 to the dried granulated material 10. The post-granulation carbonation step produces carbonates on the surface layer of the granulated material 10 and densifies the surface layer, so that the quality of the granulated material 10 can be further stabilized and carbon dioxide can be absorbed and fixed. The post-granulation carbonation step may be carried out repeatedly. By carrying out this step, a granulated material 10 with stable quality can be obtained.

[0060] Other embodiments (1) In the above embodiment, granulation is performed by mixing the granulation target 40 containing an alkali metal and / or an alkaline earth metal with the solution 51, but granulation can also be performed on the granulation target 40 that does not contain an alkali metal or an alkaline earth metal. This is because the solution 51 contains Ca, and therefore, by mixing the granulation target 40 with the solution 51 in the granulation device 2, calcium carbonate is generated, and carbon dioxide can be fixed.

[0061] (2) In the above embodiment, recovered water 50 is used as the solution 51 with carbon dioxide dissolved therein, but recovered water 50 does not have to be used. As long as carbon dioxide is dissolved therein, water within a factory, such as tap water or factory wastewater, can be used. Carbonated water generated in another facility can also be used as the solution 51. [Industrial Applicability]

[0062] INDUSTRIAL APPLICABILITY The present invention can be used for granulating a material to be granulated that contains at least one of an alkali metal and an alkaline earth metal. [Explanation of symbols]

[0063] 1: granulation system, 2: granulation device, 3: first solution adding device, 4: incineration facility, 5: concrete recycling process, 10: granulated material, 40: material to be granulated, 41: exhaust gas (gas), 50: recovered water, 51: solution

Claims

1. A granulation system for granulating a granulation target containing at least one of an alkali metal and an alkaline earth metal, A granulation system comprising a first solution adding device that adds a solution containing dissolved carbon dioxide to the material to be granulated.

2. The present invention includes a kneader for kneading the material to be granulated, and a granulator for granulating the material produced by the kneader, The granulation system according to claim 1 , wherein the first solution adding device is provided in at least one of the kneader and the granulator.

3. The granulation system according to claim 2, further comprising a carbonation device that carbonates the granulation object by contacting the granulation object with a gas containing carbon dioxide or the solution before or during kneading of the granulation object.

4. The granulation system according to claim 3 , wherein the gas or the solution is produced using a gas generated by a thermal treatment or a biological treatment.

5. The granulation system according to claim 3 , wherein the solution is carbon dioxide dissolved in recovered water generated in a concrete washing process or a concrete regeneration process.

6. The granulation system according to claim 3 , wherein the solution is carbon dioxide dissolved in recovered water generated in a sludge or soil washing process.

7. The granulation system according to any one of claims 4 to 6, wherein the granulation object includes recycled aggregate, sludge or dust generated in a concrete washing process or a concrete recycling process.

8. The granulation system according to any one of claims 4 to 6, wherein the granulation object includes biomass ash, fly ash, or slag.

9. The granulation system according to claim 2 or 3, further comprising: a dryer for drying the granulated material produced by the granulator; and a second solution adding device for adding the solution to the dried granulated material.

10. The method includes a kneading step of kneading a material to be granulated that contains at least one of an alkali metal and an alkaline earth metal, and a granulation step of granulating the material produced by the kneading step, A method for producing a granulated product, comprising adding a solution in which carbon dioxide is dissolved in at least one of the kneading step and the granulation step.

11. The method for producing a granulated material according to claim 10, further comprising a pre-granulation carbonation step for carbonating the granulated material by contacting the granulated material with a gas containing carbon dioxide or the solution, prior to the kneading step.

12. The method for producing a granulated material according to claim 11, further comprising a drying step of drying the granulated material produced by the granulation step, and a post-granulation carbonation step of carbonating the granulated material by adding the solution to the granulated material dried by the drying step.

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