Method for extracting methane gas, method for extracting raw material of cement, resource recycling method, concrete, resource recycling system, and concrete recycling system

Abstract

To utilize waste concrete.SOLUTION: In the methane gas extraction method, methane gas is extracted based on concrete in which at least a part of the surface is oxidized by a concrete preparation step of preparing concrete in which at least a part of the surface is oxidized, a concrete pulverization step of pulverizing the concrete in which at least a part of the surface is oxidized prepared in the concrete preparation step, a concrete carbonation step of carbonating the concrete pulverized in the concrete pulverization step, and a methanation step of methanating the concrete oxidized in the concrete carbonation step.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to the treatment of large amounts of waste concrete generated by the demolition of buildings. [Background technology]

[0002] The demolition of buildings generates a large amount of waste concrete rubble, and disposal of this large amount of waste concrete rubble has become an issue. Concrete is made by adding admixtures such as gravel to the raw material cement. Figure 9 shows the conventional concrete manufacturing process.

[0003] Cement is produced by mixing limestone (CaCO3, also known as calcium carbonate) with clay and other ingredients and firing it at high temperatures. During the cement manufacturing process at cement factories, calcium carbonate is thermally decomposed into calcium oxide and carbon dioxide, emitting carbon dioxide. Firing requires a temperature of approximately 1,450°C, and if fossil fuels are used for firing, even more carbon dioxide will be emitted.

[0004] Calcium oxide is used as a raw material for cement to form concrete, but over time the exterior of the concrete oxidizes (neutralizes) and turns into calcium carbonate (CaCO3). Concrete used in buildings is eventually dismantled and crushed into waste concrete.

[0005] Technology is advancing to fix carbon dioxide in waste concrete and reuse the resulting limestone as construction materials or roadbed material, but because there is little demand for waste concrete with fixed carbon dioxide, it remains difficult to dispose of large amounts of waste concrete. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2022-162955 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to reuse concrete whose surface has been oxidized. [Means for solving the problem]

[0008] One form of the present invention for solving the above-mentioned problems is characterized by a method for extracting methane gas from concrete with at least a portion of its surface oxidized, comprising: a concrete preparation step for preparing concrete with at least a portion of its surface oxidized; a concrete crushing step for crushing the concrete with at least a portion of its surface oxidized prepared in the concrete preparation step; a concrete carbonation step for carbonate the concrete crushed in the concrete crushing step; and a methanation step for methanating the concrete oxidized in the concrete carbonation step.

[0009] According to this embodiment, it is possible to obtain an effect that methane gas can be extracted from concrete whose surface is oxidized when a building is demolished.

[0010] In another aspect of the present invention, the method comprises the steps of: preparing concrete having at least a portion of its surface oxidized; crushing the concrete having at least a portion of its surface oxidized prepared in the concrete preparation step; carbonating the concrete crushed in the concrete crushing step; and methanating the concrete oxidized in the carbonation step, wherein cement raw materials are extracted from concrete having at least a portion of its surface oxidized.

[0011] According to this embodiment, it is possible to extract raw materials for cement from concrete whose surface is oxidized, which is generated when a building is demolished.

[0012] In another embodiment of the present invention, the method comprises: a carbon dioxide capture step of capturing carbon dioxide generated when producing cement from limestone; a concrete preparation step of preparing concrete with at least a portion of its surface oxidized; a concrete crushing step of crushing the concrete prepared in the concrete preparation step; a carbonation step of carbonate the concrete crushed in the concrete crushing step using carbon dioxide captured in the carbon dioxide capture step; and a methanation step of methanating the concrete oxidized in the carbonation step, wherein the raw materials for cement are extracted from the oxidized concrete.

[0013] According to this embodiment, carbon dioxide generated when producing cement from limestone can be recovered, and the recovered carbon dioxide can be used to extract raw materials for cement from concrete whose surface has been oxidized when a building is demolished, thereby achieving the effect of reducing carbon dioxide emissions.

[0014] Another embodiment of the present invention is a resource circulation method comprising: a carbon dioxide recovery step of recovering carbon dioxide generated when producing cement from limestone; a concrete preparation step of preparing concrete with at least a portion of its surface oxidized; a concrete crushing step of crushing the concrete prepared in the concrete preparation step; an aggregate recovery step of recovering aggregate from the concrete by the concrete crushing step; a carbonation step of carbonated concrete crushed in the concrete crushing step using the carbon dioxide recovered by the carbon dioxide recovery step; a methanation step of methanating the concrete oxidized by the carbonation step; and constructing concrete from the cement raw material obtained by the methanation step and the aggregate recovered by the aggregate recovery step.

[0015] According to this embodiment, it is possible to obtain an effect that aggregate can be recovered from concrete generated when a building is demolished.

[0016] Another embodiment of the present invention is characterized by a carbon dioxide capture process for capturing carbon dioxide generated when producing cement from limestone; a concrete preparation process for preparing concrete with at least a portion of its surface oxidized; a concrete crushing process for crushing the concrete prepared in the concrete preparation process; an aggregate recovery process for recovering aggregate from the concrete by the concrete crushing process; a carbonation process for carbonate the concrete crushed in the concrete crushing process using the carbon dioxide recovered in the carbon dioxide capture process; and a methanation process for methanating the concrete oxidized in the carbonation process; and concrete composed of the cement raw materials obtained in the methanation process and the aggregate recovered in the aggregate recovery process.

[0017] According to this embodiment, it is possible to recover aggregate that was used in concrete generated when a building was demolished, and reuse the aggregate in concrete.

[0018] Another embodiment of the present invention is a resource circulation system comprising: a carbon dioxide capture process for capturing carbon dioxide generated when producing cement from limestone; a concrete preparation process for preparing concrete with at least a portion of its surface oxidized; a concrete crushing process for crushing the concrete prepared in the concrete preparation process; an aggregate recovery process for recovering aggregate from the concrete by the concrete crushing process; a carbonation process for carbonate the concrete crushed in the concrete crushing process using the carbon dioxide captured in the carbon dioxide capture process; a power generation process for generating electricity using renewable energy; a methanation process for methanating the concrete oxidized in the carbonation process using the electricity generated in the power generation process; and concrete is obtained from the cement raw material obtained in the methanation process and the aggregate recovered in the aggregate recovery process.

[0019] According to this embodiment, it is possible to recover the concrete generated when a building is demolished and the aggregate used in that concrete, and further, by performing methanation using electricity generated by renewable energy, it is possible to construct a resource circulation system that suppresses the generation of carbon dioxide.

[0020] Another embodiment of the present invention is a concrete recycling system comprising: a concrete crushing process for crushing concrete; a carbonation device for carbonating the concrete crushed in the concrete crushing process; and a methanation device for methanating the concrete oxidized by the carbonation device.

[0021] According to this embodiment, it is possible to easily recycle concrete generated when a building is demolished.

[0022] Another embodiment of the present invention is a concrete recycling system comprising: a concrete crushing process for crushing concrete; a carbonation device for carbonating the concrete crushed in the concrete crushing process in an atmosphere of 20°C or higher but lower than 50°C; and a methanation device for methanating the concrete oxidized by the carbonation device.

[0023] According to this embodiment, it is possible to efficiently oxidize pulverized concrete under specific conditions.

[0024] Another aspect of the present invention is a concrete recycling system comprising a concrete crushing device that crushes concrete, a carbonation device that carbonates the concrete crushed by the concrete crushing device, and a methanation device that methanates the concrete oxidized by the carbonation device, and is configured to further carbonate the concrete methanated by the methanation device using the carbonation device.

[0025] According to this embodiment, by methanating carbonated concrete and further carbonating the methanated concrete, it is possible to efficiently regenerate concrete. [Effects of the Invention]

[0026] According to the present invention, methane gas and cement material can be obtained from concrete with at least a portion of the surface oxidized. [Brief explanation of the drawings]

[0027] [Figure 1] FIG. 1 is a diagram showing the process from dismantling a building to obtaining cement materials. [Figure 2] 1 is a diagram showing a concrete crushing process. FIG. [Figure 3] FIG. 1 is a diagram showing that carbon dioxide generated in a cement manufacturing process is used as carbon dioxide for the carbonation process. [Figure 4] FIG. 1 is a diagram showing a process when a carbonation step and a methanation step are performed alternately. [Figure 5] FIG. 1 is a diagram showing how waste concrete is recycled as a material for new concrete. [Figure 6] 1 is an example showing the arrangement of a carbonation device and a methanation device. [Figure 7] 10 is another example showing the arrangement of a carbonation device and a methanation device. [Figure 8] 10 is another example showing the arrangement of a carbonation device and a methanation device. [Figure 9] FIG. 1 illustrates a conventional technique. DETAILED DESCRIPTION OF THE INVENTION

[0028] Hereinafter, an example of extracting methane gas from concrete whose surface has been partially oxidized, which is one embodiment of the present invention, will be described with reference to the accompanying drawings.

[0029] Figure 1 shows the overall system for obtaining recycled materials from waste concrete. The process of the system will be explained below.

[0030] <Concrete preparation process S200> When demolition work S100 of a reinforced concrete building or the like is carried out, concrete waste (also referred to as "waste concrete") is generated. The generated waste concrete may be treated as a lump of concrete from which reinforcing steel, admixtures, aggregates, etc. have been removed. The waste concrete has oxidized over time, with part or all of its surface oxidized over time. Here, "concrete with at least a portion of its surface oxidized" refers to a collection of concrete that includes concrete with a portion of its surface oxidized, and does not mean that all concrete is oxidized. It may also be a collection of oxidized and non-oxidized concrete.

[0031] <Concrete crushing process S300> Figure 2 shows the concrete crushing step S300. The concrete blocks obtained in the concrete preparation step S200 are crushed by a concrete crushing device at a demolition site or an intermediate processing plant. The concrete crushing step S300 may be a single crushing step, or may be crushed through multiple concrete crushing steps S310 and S320.

[0032] When multiple concrete crushing steps S310, S320 are employed, a primary crushing step S310 for coarsely crushing concrete chunks and a sieving and separation step S315 for sieving and separating the coarsely crushed concrete pieces may be provided.

[0033] The waste concrete sieved in the sieving and separating step S315 may be crushed into smaller pieces in the secondary crushing step S320. The waste concrete pieces crushed in the secondary crushing step S320 may be further sieved in the sieving and separating step S325.

[0034] <Primary crushing process S310> The concrete blocks generated when a reinforced concrete building is demolished are pre-processed to separate them from the attached rebar, breaking them into smaller pieces, and transported to an intermediate processing plant as concrete blocks of original size, approximately 200-400mm in size. At the intermediate processing plant, the blocks are then coarsely crushed to approximately 150mm in size as the primary crushing process. A jaw crusher or similar machine is used as the primary crusher.

[0035] <Secondary grinding process S320> In the secondary crushing process, the waste concrete is crushed using an impact crusher or various known crushers and grinders, and recycled aggregate is produced. This is then passed through a classifier to produce recycled aggregate of specified standards (recycled coarse aggregate, recycled fine aggregate).

[0036] <Fine powder process> The waste concrete that has been subjected to the crushing step S300 may be further crushed into fine powder in a fine powder process. The waste concrete is crushed into fine powder in a fine powder process to reduce the specific surface area to 1,000 to 8,000 cm. 2 In addition, the specific surface area of ​​the waste concrete powder can be adjusted to 3,000 to 4,000 cm 2 By making the specific surface area of ​​the waste concrete powder fall within a predetermined range, the degree of oxidation of the waste concrete powder becomes uniform, and appropriate carbonation treatment can be performed in the subsequent carbonation step.

[0037] <Sieving separation process S315, S325> In the sieving separation steps S315 and S325, the sieve residue may be crushed, ground, and classified to separate and recover coarse aggregate, fine aggregate, and fine waste concrete powder. The sieve openings in the sieving separation steps may be selected from the range of 3 mm or more and less than 20 mm. Preferably, the sieve openings are 10 mm.

[0038] The fine powder of waste concrete obtained in the sieving separation step may be separated into fine powder with advanced carbonation and fine powder without carbonation. The fine powder of waste concrete with advanced carbonation may be methanated in the methanation step without undergoing the subsequent carbonation step. Furthermore, the fine powder of waste concrete without undergoing the subsequent steps may be used as a cement material.

[0039] <Carbonation process S400> FIG. 3 shows an example of the carbonation step S400. The waste concrete that has been through the crushing step S300 is carbonated in the carbonation step S400. The crushed waste concrete can be carbonated with carbon dioxide in the atmosphere, but it is preferable that the carbon dioxide be carbonated in an atmosphere with a higher concentration than that of the atmosphere.

[0040] In the carbonation step, waste concrete can be carbonated in a short time in an atmosphere with a high concentration of carbon dioxide, but it takes a long time to carbonate the waste concrete in an atmosphere with a low concentration of carbon dioxide. The time for the carbonation step S400 can be set appropriately depending on the particle size of the waste concrete and the concentration of carbon dioxide. In addition, the temperature of the atmosphere during carbonation is preferably 20°C or higher and lower than 50°C. Within this temperature range, waste concrete can be appropriately carbonated.

[0041] It is said that when producing one ton of cement, approximately 700kg to 800kg of carbon dioxide is emitted during the production process. In order for slaked lime to produce cement, it must be calcined at approximately 1450 degrees. The calcination process required to produce one ton of cement generates 300kg to 400kg of carbon dioxide.

[0042] In the carbonation step S400, carbon dioxide (exhaust gas) generated by burning slaked lime is recovered, and the recovered carbon dioxide is used in the carbonation step S400, thereby reducing the amount of carbon dioxide generated when producing cement.

[0043] <Methanation process S500> The waste concrete carbonated in the carbonation step S400 is decomposed into calcium oxide and methane gas by a methanation reaction in the methanation step S500. The methanation reaction is a chemical reaction between calcium carbonate and hydrogen. Since water has the effect of accelerating the methanation reaction, it is desirable to add water appropriately depending on the particle size of the waste concrete.

[0044] In the methanation step S500, hydrogen generated in an SOEC (Solid Oxide Electrolysis Cell) using electricity generated from renewable energy is used, making it possible to carry out decomposition in the medium temperature range of 300°C or higher and lower than 600°C. By using electricity generated from renewable energy in the methanation step S500, carbon dioxide emissions can be reduced.

[0045] As shown in Figure 5, calcium oxide obtained by the methanation step S500 can be used as a building material, so it can be recycled and reused in the form of waste concrete, concrete (building material), waste concrete, and building material, thereby increasing the uses of waste concrete.

[0046] FIG. 6 shows an example of an apparatus that includes a concrete carbonation apparatus 400 that carbonates waste concrete in a carbonation step S400 and a methanation apparatus 500 that methanates the concrete oxidized by the concrete carbonation apparatus 400 in a methanation step 500.

[0047] <Concrete Carbonation Device 400> The concrete carbonator 400 comprises a carbonation chamber 410 and a carbon dioxide source 420 .

[0048] <Carbonation Room 410> Carbonation chamber 410 is connected to carbon dioxide supply source 420 via pipe 430. Carbonation chamber 410 is also connected to a crushing device via pipe 440, and is also connected to on-off valve 450, sensor S1, and pipe 560. Pipes 440, 560, and 570 are provided to allow the waste concrete to move, and may be conveyors or the like instead of pipes.

[0049] <Carbon dioxide source 420> Carbon dioxide supply source 420 may store carbon dioxide internally in a tank or the like, or may be supplied with carbon dioxide from the outside via a connection such as a pipe and supply carbon dioxide to carbonation chamber 410. Carbon dioxide supply source 420 may be configured to supply not only carbon dioxide but also air (atmospheric air) to carbonation chamber 410.

[0050] It is preferable that the carbon dioxide generated when burning limestone is recovered and used as the carbon dioxide supplied from the carbon dioxide supply source 420 to the carbonation chamber 410. With this configuration, it is possible to suppress the overall emission of carbon dioxide.

[0051] <Sensor S1> Sensor S1 is provided to detect the internal condition of carbonation chamber 410 and detect the state of carbonation of the waste concrete in carbonation chamber 410. Sensor S1 may detect the surface condition of the waste concrete in carbonation chamber 410, or may detect the concentration of carbon dioxide in carbonation chamber 410 to detect the carbonation of the waste concrete in carbonation chamber 410. When there is no longer any change in the concentration of carbon dioxide over time, it may be determined that the carbonation of the waste concrete has finished.

[0052] <Methanation device 500> The methanation device 500 includes a methanation chamber 510 in which a methanation reaction takes place, and a hydrogen supply source 520 that supplies hydrogen.

[0053] <Methanation Chamber 510> The methanation chamber 510 is connected to a hydrogen supply source 520 via a pipe 530. It is also connected to the concrete carbonation device 400 via a pipe 560 and to a sensor S2.

[0054] In addition, a methane gas discharger and a calcium oxide discharger (not shown) are connected to the methanation chamber 510. When the methanation process is completed, methane gas is discharged from the methane gas discharger and calcium oxide is discharged from the calcium oxide discharger from the methanation chamber 510.

[0055] <Hydrogen Source 520> The hydrogen supply source 520 is a device that supplies hydrogen for causing a methanation reaction in the methanation chamber 510. A solid oxide electrolysis cell (SOEC) can be used as the hydrogen supply source 520. The SOEC is preferably operated using electricity generated from renewable energy. By operating the SOEC using electricity generated from renewable energy, carbon dioxide emissions can be reduced.

[0056] Next, an example of the operation of the concrete carbonation device 400 and the methanation device 500 will be shown. The waste concrete pulverized in the pulverization step S300 is transported into the carbonation chamber 410 via a pipe 440. If the waste concrete is finely pulverized, it can be easily transported by water or air, or it can also be transported by a conveyor.

[0057] Carbonation chamber 410 is preferably filled with carbon dioxide from carbon dioxide supply source 420 before waste concrete is transported into carbonation chamber 410. When waste concrete is transported into carbonation chamber 410, on-off valve 450 and on-off valve 550 are closed, and carbonation of the waste concrete in carbonation chamber 410 begins.

[0058] The completion of carbonation of the waste concrete can be determined by the output of sensor S1, or the time when carbonation will be completed can be predicted based on the shape of the waste concrete (particle size) and the concentration of carbon dioxide in the carbonation chamber 410, and the carbonation process 400 can be terminated using a timer.

[0059] An agitator may be provided in the carbonation chamber 410 to promote carbonation of the waste concrete. The agitator may be configured to rotate an agitator such as a mixer, or a blower may be provided in the carbonation chamber 410 to agitate the waste concrete and carbon dioxide in the carbonation chamber 410.

[0060] When the carbonation step S400 is being performed, carbon dioxide can be supplied into the carbonation chamber 410 by the carbon dioxide supply source 420. By supplying carbon dioxide while the carbonation step S400 is being performed, the concentration of carbon dioxide in the carbonation chamber 410 can be appropriately managed, and the processing time for the carbonation step S400 can be shortened.

[0061] After the carbonation step S400 is completed, the waste concrete is transported into the methanation chamber 510 via a pipe 560. If the waste concrete is pulverized, it can be easily transported by water or air, or it can be transported by a conveyor.

[0062] It is preferable that the inside of the methanation chamber 510 is filled with hydrogen from the hydrogen supply source 520 before the waste concrete is transported into the methanation chamber 510. When the waste concrete is transported into the methanation chamber 510, the on-off valve 550 and the on-off valve 580 are closed, and methanation of the waste concrete in the methanation chamber 510 begins.

[0063] The completion of methanation of waste concrete may be determined by the output of sensor S2, or the time when methanation will be completed may be predicted based on the shape of the waste concrete (particle size) and the concentration of hydrogen in the methanation chamber 510, and the methanation process 500 may be terminated using a timer.

[0064] An agitator may be provided to promote the methanation reaction of the waste concrete in the methanation chamber 510. The agitator may be configured to rotate an agitator such as a mixer, or a blower may be provided in the methanation chamber 510 to agitate the waste concrete and hydrogen in the methanation chamber 510.

[0065] After the methanation step S500 is completed, the waste concrete is transported to the outside via a pipe 570. If the waste concrete is pulverized, it can be easily transported by water or air (atmosphere), or it may be transported by a conveyor. The water or air (atmosphere) for transporting the waste concrete can be supplied from either the carbon dioxide supply source 420 or the hydrogen supply source 520, or both.

[0066] Another embodiment is shown in FIG. In the embodiment of Figure 7, in addition to the configuration of the embodiment of Figure 6, the carbonation chamber 410 and the methanation chamber 510 are connected by a pipe 590, and hydrogen from the hydrogen supply source 520 can be supplied from above the methanation chamber 510 via a pipe 595.

[0067] According to this configuration, a circular path can be constructed by connecting the upper part of the carbonation chamber 410 and the upper part of the methanation chamber 510 with a pipe 590, and connecting the lower part of the methanation chamber 510 and the lower part of the carbonation chamber 410 with a pipe 560.

[0068] By connecting the carbonation chamber 410 and the methanation chamber 510 in a circular configuration, it is possible to easily alternate between carbonation and methanation of waste concrete. Furthermore, by supplying carbon dioxide to the lower part of the carbonation chamber 410 and hydrogen to the upper part of the methanation chamber 510, the circular path allows the waste concrete to move more smoothly, which has the effect of enabling alternate carbonation and methanation of waste concrete.

[0069] Another embodiment is shown in FIG. In the embodiment of FIG. 8, in addition to the configuration of the embodiment of FIG. 6, the carbonation chamber 410 and the methanation chamber 510 are connected by a pipe 590.

[0070] According to this configuration, a circular path can be constructed by connecting the carbonation chamber 410, the upper part of the carbonation chamber 410 and the lower part of the methanation chamber 510 with a pipe 590, and connecting the upper part of the methanation chamber 510 and the lower part of the carbonation chamber 410 with a pipe 560.

[0071] By connecting the carbonation chamber 410 and the methanation chamber 510 in a circular configuration, it is possible to easily alternate between carbonation and methanation of waste concrete. In addition, by configuring the carbonation chamber 410 to supply carbon dioxide from the bottom and the methanation chamber 510 to supply hydrogen from the bottom, carbonation and methanation can be alternately performed more smoothly through a circular path. In addition, by configuring the waste concrete to move upward with each gas, the contact time between the waste concrete, which tends to fall vertically downward due to gravity, and the gas supplied vertically upward can be extended, resulting in the efficiency of each reaction.

[0072] <Carbon dioxide reduction> The amount of carbon dioxide reduction achieved by the present invention is calculated using a simple method under the following conditions. 1. Cement processing capacity: 1 ton 2. Cement content in concrete: 15% (amount of waste concrete processed: 6.7 tons) 3. Cement components: CaCO3 only 4. Conventional technology does not take material recycling into consideration 5. The present invention and the prior art have the same fuel efficiency, transportation costs, and power consumption in the crushing process. 6.Methanation transfer rate: 90% (300℃) 7. Carbonation rate: 100%

[0073] <Computation result> Required energy input heat quantity (Qold) based on the specific heat of concrete (1.05 kJ / (kg K)) according to conventional technology: Qold=96.6×10 5 kj Required energy input heat (Qnew) from the concrete specific heat (1.05 kJ / (kg K)) according to the present invention: Qnew = 26.6 × 10 5 kj The calculation result is obtained, and the reduction rate of required energy is 72.5%. Since it is recognized that there is a correlation between the required energy and the amount of carbon dioxide emitted, it can be said that according to the present invention, the amount of carbon dioxide emitted for processing cement can be reduced by 72.5%. [Explanation of symbols]

[0074] 400...carbonation device, 410...carbonation chamber, 420...carbon dioxide supply device 500...methanation device, 510...methanation chamber, 520...hydrogen supply source

Claims

1. a concrete preparation step of preparing concrete having at least a portion of its surface oxidized; a concrete crushing step of crushing the concrete having at least a portion of its surface oxidized, which has been prepared in the concrete preparation step; a concrete carbonation step of carbonating the concrete pulverized in the concrete pulverization step; a methanation step of methanating the concrete oxidized by the concrete carbonation step; A method for extracting methane gas from concrete having at least a portion of its surface oxidized by the above method.

2. a concrete preparation step of preparing concrete having at least a portion of its surface oxidized; a concrete crushing step of crushing the concrete prepared in the concrete preparation step, the concrete having at least a portion of its surface oxidized; a concrete carbonation step of carbonating the concrete pulverized in the concrete pulverization step; a methanation step of methanating the concrete oxidized by the carbonation step; A method for extracting raw materials for cement from concrete, at least part of whose surface has been oxidized by the oxidation of the concrete.

3. a carbon dioxide recovery step of recovering carbon dioxide generated when producing cement from limestone; a concrete preparation step of preparing concrete having at least a portion of its surface oxidized; a concrete crushing step of crushing the concrete prepared in the concrete preparation step; a concrete carbonation step of carbonating the concrete pulverized in the concrete pulverization step using the carbon dioxide recovered in the carbon dioxide recovery step; a methanation step of methanating the concrete oxidized by the concrete carbonation step; A method for extracting raw materials for cement based on oxidized concrete.

4. a carbon dioxide recovery step of recovering carbon dioxide generated when producing cement from limestone; a concrete preparation step of preparing concrete having at least a portion of its surface oxidized; a concrete crushing step of crushing the concrete prepared in the concrete preparation step; an aggregate recovery step of recovering aggregate from the concrete by the concrete crushing step; a carbonation step of carbonating the concrete pulverized in the concrete pulverization step using the carbon dioxide recovered in the carbon dioxide recovery step; a methanation step of methanating the concrete oxidized by the carbonation step; A resource circulation method for forming concrete containing the cement raw material obtained in the methanation step and the aggregate recovered in the aggregate recovery step.

5. a carbon dioxide recovery step of recovering carbon dioxide generated when producing cement from limestone; a concrete preparation step of preparing concrete having at least a portion of its surface oxidized; a concrete crushing step of crushing the concrete prepared in the concrete preparation step; an aggregate recovery step of recovering aggregate from the concrete by the concrete crushing step; a concrete carbonation step of carbonating the concrete pulverized in the concrete pulverization step using the carbon dioxide recovered in the carbon dioxide recovery step; a methanation step of methanating the concrete oxidized by the concrete carbonation step; Concrete formed from the cement raw material obtained by the methanation step and the aggregate recovered by the aggregate recovery step.

6. a carbon dioxide recovery step of recovering carbon dioxide generated when producing cement from limestone; a concrete preparation step of preparing concrete having at least a portion of its surface oxidized; a concrete crushing step of crushing the concrete prepared in the concrete preparation step; an aggregate recovery step of recovering aggregate from the concrete by the concrete crushing step; a concrete carbonation step of carbonating the concrete pulverized in the concrete pulverization step using the carbon dioxide recovered in the carbon dioxide recovery step; a power generation process for generating electricity using renewable energy; a methanation step in which the concrete oxidized in the carbonation step is methanated using the electricity generated in the power generation step; A resource circulation system in which concrete is formed from the cement raw material obtained in the methanation step and the aggregate recovered in the aggregate recovery step.

7. a concrete crushing device for crushing concrete; a concrete carbonation device that carbonates the concrete pulverized by the concrete pulverization device; a methanation device that methanates the concrete oxidized by the concrete carbonation device; Equipped with Concrete recycling system.

8. The carbonation device performs carbonation in an atmosphere of 20°C or higher and lower than 50°C, The methanation device performs methanation in a temperature range of 300 degrees or higher and lower than 600 degrees. The concrete recycling system according to claim 7.

9. The concrete methanated by the methanation device is further carbonated by the carbonation device. The concrete recycling system according to claim 7.

Images