Manufacturing method of carbon material-containing slurry, and deep ground improving method

Abstract

To provide a technology that can increase an amount of carbon dioxide absorbed in deep underground.SOLUTION: In a manufacturing method of a carbon material-containing slurry to be discharged into deep ground, the carbon material-containing slurry contains at least water and a carbon material. The manufacturing method includes a mixing step of mixing the water and the carbon material.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing a carbonaceous material-containing slurry and a deep soil improvement method. [Background technology]

[0002] Patent Documents 1 and 2 describe a road construction method in which a reinforcing mesh is laid on top of multiple pillars, and a shallow improved soil layer is laid on top of the reinforcing mesh by adding either an additive or additives or both to the soil and solidification material, mixing and solidifying, and then constructing road pavement on top of the shallow improved soil layer, and describe the use of rice husks or foam beads as the additives or additives.

[0003] Patent Document 3 describes a lightweight cement-based solidification material that is a mixture of cement-based solidification material and threshing waste such as rice husks, and Patent Document 4 describes the mixing of threshing waste such as rice husks into a ground improvement material that is made by mixing a cement-based solidification material with in-situ soil and sand. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-239276 [Patent Document 2] Japanese Patent Application Publication No. 10-317307 [Patent Document 3] Japanese Patent Application Publication No. 7-330406 [Patent Document 4] Japanese Patent Application Publication No. 7-180138 Summary of the Invention [Problem to be solved by the invention]

[0005] There are active efforts to achieve a decarbonized society that aims for zero carbon dioxide emissions, and the construction industry is also being asked to reduce its carbon dioxide emissions. Carbon neutrality is one of the decarbonization efforts to combat global warming. Carbon neutrality is an effort to achieve "virtually zero" carbon dioxide emissions by offsetting carbon dioxide emissions and absorption.

[0006] Therefore, even in in-situ stabilization, in which hardener slurry is injected into the ground and mixed with the ground in situ (underground), there is a need to reduce carbon dioxide emissions and incorporate processes that can fix the emitted carbon dioxide underground in order to approach "virtually zero" carbon dioxide emissions. However, in mid-layer and deep-layer mixing processes in in-situ stabilization, adding carbonizing materials to the hardener slurry, which is a solidification material mixed to improve the original ground underground, is physically difficult due to the structure of the machines used for improvement. Here, hardener slurry refers to a slurry made by mixing a hardener, such as cement, with water. Methods for mixing deep ground with hardener slurry in in-situ stabilization include mechanical mixing (also known as mechanical mixing) and high-pressure injection (also known as high-pressure injection mixing).

[0007] One aspect of the present invention has been made in consideration of the above-mentioned problems, and aims to realize a technology that can fix carbon dioxide in deep ground during ground improvement in deep ground. [Means for solving the problem]

[0008] In order to solve the above problems, a method for producing a carbonaceous material-containing slurry according to one aspect of the present invention is a method for producing a carbonaceous material-containing slurry to be discharged into deep ground. In this production method, the carbonaceous material-containing slurry contains at least water and a carbonaceous material. The production method includes a mixing step of mixing the water and the carbonaceous material.

[0009] In order to solve the above problems, a deep soil improvement method according to one aspect of the present invention includes a discharging step and an in-situ mixing step. In this manufacturing method, the discharging step is a step of discharging a carbonaceous material-containing slurry manufactured by the method for manufacturing a carbonaceous material-containing slurry according to one aspect of the present invention into deep soil using a deep soil improvement machine, and the in-situ mixing step is a step of mixing the carbonaceous material-containing slurry discharged into the deep soil with the deep soil using the deep soil improvement machine in situ. [Effects of the Invention]

[0010] According to one aspect of the present invention, carbon dioxide can be fixed in deep underground. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram showing an outline of a deep soil improvement machine 100 for carrying out a carbonaceous material-containing slurry manufacturing method and a mechanical stirring method according to an embodiment of the present invention. [Figure 2] 2 is an enlarged side view of the essential parts showing the tip portions of a pair of rods 21 and 22 provided in the mixer 20 shown within the dashed dotted line in FIG. 1. FIG. [Figure 3] 10 is a schematic diagram illustrating a mechanical stirring method for discharging the carbon material mixed hardening material slurry SR1 on the return path. FIG. [Figure 4] FIG. 10 is a schematic diagram illustrating a mechanical stirring method for discharging the carbon material-mixed hardening material slurry SR1 on the outward path. [Figure 5] 10 is a schematic diagram illustrating a mechanical stirring method for discharging the carbon material-mixed hardening material slurry SR1 in both the forward and backward directions. FIG. [Figure 6] 10 is a schematic diagram illustrating a mechanical stirring method in which a carbon material slurry SR2 is discharged on the outward path and a hardening material slurry SR3 is discharged on the return path. FIG. [Figure 7] FIG. 2 is a schematic diagram for explaining the separation and dispersion state of the carbon material in the hardener slurry. DETAILED DESCRIPTION OF THE INVENTION

[0012] [Summary of carbonaceous material-containing slurry manufacturing method and deep ground improvement method] A method for producing a carbonaceous material-containing slurry according to one aspect of the present invention is a method for producing a carbonaceous material-containing slurry to be discharged into deep ground. In this production method, the carbonaceous material-containing slurry contains at least water and a carbonaceous material. The production method includes a mixing step of mixing the water and the carbonaceous material.

[0013] In the following, carbonaceous material refers to a material made of charcoal. Carbonaceous material is obtained by carbonizing plants or plant-derived materials. Charcoal made from plants or plant-derived materials is also called biochar, and is persistent. By fixing carbon underground for a long period of time, the amount of carbon stored can be certified as a credit. Examples of plants that can be used as raw materials include wood and bamboo, and examples of plant-derived materials include rice husks. Plants grow by photosynthesis. Therefore, carbonaceous material obtained from plants or plant-derived materials can be considered a material that absorbs carbon dioxide.

[0014] Hereinafter, among carbonaceous material-containing slurries, a slurry containing water and a carbonaceous material but not a curing material will be referred to as a carbonaceous material slurry. Also, among carbonaceous material-containing slurries, a slurry containing water, a carbonaceous material, and a curing material will be referred to as a carbonaceous material-mixed curing material slurry. When producing a carbonaceous material-mixed curing material slurry, the mixing step involves mixing water, a carbonaceous material, and a curing material. Thus, the method for producing a carbonaceous material-containing slurry according to one aspect of the present invention includes a method for producing a carbonaceous material slurry and a method for producing a carbonaceous material-mixed curing material slurry.

[0015] The carbonaceous material-containing slurry produced in this manner contains carbonaceous material that has absorbed carbon dioxide during the growth process. Therefore, by discharging the carbonaceous material-containing slurry into deep ground, carbon dioxide can be fixed in the deep ground. The amount of carbon dioxide fixed in the deep ground (fixed amount) can also be expressed as the amount of carbon dioxide stored in the deep ground.

[0016] Furthermore, in a method for producing a carbonaceous material-containing slurry according to one embodiment of the present invention, a carbonaceous material selection step may be carried out before the mixing step, in which the carbonaceous material is selected by sieving the carbonaceous material, and the mixing step may be configured to mix the carbonaceous material that has passed through the sieve in the carbonaceous material selection step with the water.

[0017] The carbonaceous material-containing slurry is discharged into deep ground using a deep ground improvement machine. The carbonaceous material-containing slurry is a fixing material that fixes carbon dioxide in the deep ground by mixing the carbonaceous material with soil and sand in the deep ground in situ. A deep ground improvement method including a discharge step and an in-situ mixing step in a deep ground improvement method performed using the carbonaceous material-containing slurry as the fixing material is also included in the scope of the present invention. The discharge step is a step of discharging the carbonaceous material-containing slurry produced by the carbonaceous material-containing slurry production method according to one aspect of the present invention into deep ground using a deep ground improvement machine, and the in-situ mixing step is a step of mixing the carbonaceous material-containing slurry discharged into the deep ground with the deep ground in situ using the deep ground improvement machine. Deep ground can be broadly divided into deep ground located on the seabed and deep ground located on land. Deep ground located on the seabed is often a clay ground with a high proportion of clay among its constituent soil and sand, while deep ground located on land is often a sand ground with a high proportion of sand among its constituent soil and sand. The carbonaceous material-containing slurry produced by the method for producing a carbonaceous material-containing slurry according to one aspect of the present invention and the deep ground improvement method according to one aspect of the present invention can be applied to deep ground in general, regardless of whether it is located on the seabed or on land. In other words, in each embodiment described below, the composition of the soil and sand in the deep ground is not limited. Furthermore, one aspect of the present invention will be described below using deep ground located on the seabed as an example of deep ground.

[0018] In addition, when the carbonaceous material-containing slurry is a carbonaceous material slurry, a hardening material slurry is separately discharged into the deep ground to harden the deep ground. In other words, the discharge step is carried out on either the outward path of penetrating the pipe and the stirring blade into the deep ground or the return path of withdrawing the pipe and the stirring blade from the deep ground, and the in-situ mixing step is carried out after the discharge step is carried out or simultaneously with the discharge step.

[0019] Further, when the carbonaceous material-containing slurry is a carbonaceous material-mixed hardener slurry, the hardener is contained in the carbonaceous material-mixed hardener slurry. Therefore, in this case, the hardener slurry may or may not be separately discharged into the deep ground. In other words, the discharge process is carried out on either the outward path of penetrating the pipe and the stirring blade into the deep ground, or the return path of withdrawing the pipe and the stirring blade from the deep ground, or both, and the in-situ mixing process is carried out after the discharge process is carried out or simultaneously with the discharge process. In addition, the carbonaceous material-mixed hardener slurry containing a hardener is a fixation material that fixes carbon dioxide in the deep ground, and is also an improvement material that improves the deep ground.

[0020] Hereinafter, the portion of deep ground that has been hardened by mixing with a carbonaceous material slurry and a hardening material slurry, or the portion of deep ground that has been hardened by mixing with a carbonaceous material-mixed hardening material slurry, will also be referred to as an improved body. The portion referred to as an improved body is the portion of deep ground where ground improvement has been completed. Note that the ground that is the target of ground improvement is soft ground. In other words, the soil and sand that is mixed with the carbonaceous material-containing slurry in situ is often soft clay.

[0021] In the following, first, as a first embodiment, a mechanical mixing method in a deep soil improvement method and a deep soil improvement machine used in the method will be described. Next, a method for producing a carbonaceous material-containing slurry will be described. Specifically, as a second embodiment, a case where the carbonaceous material-containing slurry is a carbonaceous material-mixed hardening material slurry will be described, and as a third embodiment, a case where the carbonaceous material-containing slurry is a carbonaceous material slurry will be described.

[0022] [First embodiment] <Deep ground improvement machine> A deep soil improvement machine 100 according to one embodiment of the present invention will be described with reference to Figures 1 and 2. Figure 1 is a schematic diagram showing an outline of the deep soil improvement machine 100. The deep soil improvement machine 100 is suitable as a deep soil improvement machine for carrying out a carbonaceous material-containing slurry manufacturing method and a mechanical mixing method according to one embodiment of the present invention. Figure 2 is a side view of a main part showing an enlarged view of the tip portions of a pair of rods 21, 22 provided in a mixer 20 shown within the dashed dotted line in Figure 1.

[0023] The deep soil improvement machine 100 shown in Figure 1 is a system for performing a mechanical mixing method (CDM method), which is a type of deep soil mixing method. The deep soil mixing method is a method for producing stabilized soil in deep layers by supplying cement-based stabilizers into the ground and mixing them with in-situ soil and sand. Here, the mechanical mixing method will be used as an embodiment of the deep soil mixing method.

[0024] However, the deep mixing method may be a high-pressure injection method (high-pressure injection mixing method) instead of a mechanical mixing method. The high-pressure injection method is described, for example, in "Ground Improvement Manual with Cement-Based Solidification Materials," 5th Edition, Cement Association of Japan, Gihodo Publishing Co., Ltd., October 25, 2021, pp. 219-221, and "Evolving Ground Improvement Technology Using the 'High-Pressure Injection Mixing Method,'" [online], January 4, 2023, ConCom, [searched February 6, 2023], Internet.<https: / / concom.jp / contents / countermeasure / column / vol42.html> It is widely known as described in

[0025] The deep soil improvement machine 100 comprises a slurry plant 10 that carries out a manufacturing method according to one embodiment of the present invention, and a mixer 20 that carries out a deep soil improvement method according to one embodiment of the present invention.

[0026] The slurry plant 10 is equipped with a measuring section 11, a mixer 12, a flow meter 13, and may also be equipped with an agitator 14 and a foaming machine 15.

[0027] When producing a carbonaceous material slurry as the carbonaceous material-containing slurry, the measuring unit 11 measures at least the carbonaceous material and water. When producing a carbonaceous material-mixed hardener slurry as the carbonaceous material-containing slurry, the measuring unit 11 also measures a hardener. The measuring unit 11 also measures an admixture to be added as needed. The measuring unit 11 can control the amounts of the carbonaceous material, water, hardener, and admixture based on data on the flow rate of the carbonaceous material-containing slurry measured by the flowmeter 13. In the following, when there is no need to distinguish between the carbonaceous material-mixed hardener slurry and the carbonaceous material slurry, both will be collectively referred to as the carbonaceous material-containing slurry.

[0028] The mixer 12 mixes the carbonaceous material measured by the measuring unit 11 with water, and optionally further mixes in at least one of a hardener and an admixture to produce a carbonaceous material-containing slurry. Specifically, when producing a carbonaceous material slurry as the carbonaceous material-containing slurry, the mixer 12 mixes at least the carbonaceous material and water. Furthermore, when producing a carbonaceous material-mixed hardener slurry as the carbonaceous material-containing slurry, the mixer 12 further mixes in a hardener. In this way, the mixer 12 carries out the mixing step of the method for producing a carbonaceous material-containing slurry according to one embodiment of the present invention. The produced carbonaceous material-containing slurry is transferred from the mixer 12 to the agitator 14. The agitator 14 agitates the carbonaceous material-containing slurry, and pressure-feeds the carbonaceous material-containing slurry to the mixer 20 using the pump P. Furthermore, a backhoe can be cited as another form of carrying out the mixing step instead of a mixer.

[0029] The flow meter 13 is interposed between the agitator 14 and the mixer 20. The flow meter 13 measures the flow rate of the carbonaceous material-containing slurry supplied from the agitator 14 and transmits data on the flow rate to the measuring unit 11.

[0030] Air bubbles may be mixed into the carbon-containing slurry when it is produced. By mixing air bubbles into the carbonaceous material-containing slurry when it is produced, the fluidity of the carbon-containing slurry can be increased, and therefore the possibility of clogging a pipe can be reduced in the process of pumping the carbonaceous material-containing slurry through a pipe. Furthermore, by mixing air bubbles into the carbonaceous material-containing slurry, it is possible to ensure that the materials do not separate.

[0031] When mixing air bubbles into the carbonaceous material-containing slurry, it is preferable to supply air bubbles generated by the foaming machine 15 to the mixer 12. The foaming machine 15 can form air bubbles by mixing a foaming agent and a diluent with compressed air. The air bubbles formed by the foaming machine 15 are supplied from the foaming machine 15 to the mixer 12, and are mixed into the carbonaceous material-containing slurry by the mixer 12. When supplying air bubbles from the foaming machine 15 to the mixer 12, it is preferable to supply the air bubbles to the mixer 12 while controlling the flow rate of the air bubbles using a flow meter and a pump with a flow control function, not shown in FIG. 1. In this way, the foaming machine 15 and the mixer 12 perform the air bubble mixing step of the method for producing a carbonaceous material-containing slurry according to one embodiment of the present invention. The gas supplied to the foaming machine 15 to generate air bubbles in this air bubble mixing step may be air or exhaust gas having a higher carbon dioxide content than air. The foaming machine 15 compresses the supplied gas using a compressor and supplies the compressed gas (e.g., compressed air) to the mixer 12. When exhaust gas is used as the gas to be supplied to the foaming machine 15, an internal combustion engine provided in the construction machine can be used as the exhaust gas supply source. The construction machine is not particularly limited, but examples thereof include heavy machinery and work boats. The internal combustion engine may be one provided for the purpose of supplying power or for the purpose of supplying electricity. When a backhoe is used as a component for performing the mixing process, the exhaust gas discharged by the backhoe may be supplied to the foaming machine 15.

[0032] The mixer 20 is equipped with a pair of double rods 21, 22 through which the carbonaceous material-containing slurry passes, and is configured so that the rods 21, 22 are rotated synchronously by a motor (not shown) or the like, and the rods 21, 22 are moved up and down (penetrated and withdrawn) relative to the ground G, which is deep ground. Hereinafter, the step of penetrating the stirring blades 211, 221 of the rods 21, 22 into the ground G will also be referred to as the outgoing path, and the step of withdrawing the stirring blades 211, 221 from the ground G will also be referred to as the returning path. The stirring blades 211, 221 will be described later.

[0033] As shown in Fig. 2, each of the pair of rods 21, 22 includes a cylindrical pipe. The pair of rods 21, 22 includes agitating blades 211, 221 protruding from each pipe along a direction perpendicular to the rod axis, rod tips 212, 222, and first discharge ports 213, 223 located near the tips 212, 222 and opening in circumferentially opposite directions at 180 degrees. The pair of rods 21, 22 also includes a fixed discharge pipe 23 fixed between the rods 21, 22 via a pair of upper and lower bearings 214, 224, and a second discharge port 231 located below the fixed discharge pipe 23 and approximately in the center between the rods 21, 22. The rods 21, 22 are rotatably fixed by the pair of upper and lower bearings 214, 224 located above the agitating blades 211, 221.

[0034] The stirring blades 211 are composed of stirring blades 211a located at the upper level in a side view of the rod 21, stirring blades 211b located at the middle level, and stirring blades 211c located at the lower level and formed like blades. The stirring blades 221 are composed of stirring blades 221a located at the upper level in a side view of the rod 22, stirring blades 221b located at the middle level, and stirring blades 221c located at the lower level and formed like blades.

[0035] In the rod 21, the agitating blades 211a and 211b are arranged in directions perpendicular to each other, and in the rod 22, the agitating blades 221a and 221b are arranged in directions perpendicular to each other. In addition, in the pair of rods 21 and 22, the agitating blades 211a and 221a are arranged in directions perpendicular to each other, and the agitating blades 211b and 221b are arranged in directions perpendicular to each other. As a result, when the mixer 20 drives the rods 21 and 22 to rotate synchronously, the agitating blades 211 and 221 do not come into contact with each other, and agitate the vicinity and directly above the first discharge ports 213 and 223 and directly below the second discharge port 231.

[0036] The mixer 20 selects the rotation direction of the rods 21, 22 (more specifically, the agitating blades 211, 221) from forward rotation and reverse rotation. In this embodiment, rotation in the direction in which the agitating blades 211, 221 penetrate the ground G is called forward rotation, and rotation in the direction in which the agitating blades 211, 221 are pulled out of the ground G is called reverse rotation. The mixer 20 can change the penetration speed, pull-out speed, and rotation speed. Furthermore, the mixer 20 can control switching between discharging and not discharging slurry from the first discharge ports 213, 223 and switching between discharging and not discharging slurry from the second discharge port 231. Furthermore, the mixer 20 may be configured to discharge one of the carbonaceous material-containing slurry and the hardening material slurry from the first discharge ports 213, 223, and to discharge the other of the carbonaceous material-containing slurry and the hardening material slurry from the second discharge port 231. Furthermore, the mixer 20 may be configured to be able to select whether to discharge a carbon material slurry or a carbon material-mixed hardening material slurry as the carbon material-containing slurry when discharging the carbon material-containing slurry from either the first discharge ports 213, 223 or the second discharge port 231. According to these configurations, the mixer 20 can independently select the slurry to be discharged onto the ground G on the outbound path and the slurry to be discharged onto the ground G on the return path. Furthermore, the mixer 20 can select the slurry to be discharged on each of the outbound path and the return path from the carbon material slurry, the carbon material-mixed hardening material slurry, and the hardening material slurry, respectively.

[0037] When mechanically stirring, it is advisable to check the construction position using GNSS or a photometer, check the water depth at the bottom of the water, and check the depth and inclinometer zero of the rods 21 and 22, and to control the penetration speed and rotation speed of the rods 21 and 22, as well as the withdrawal speed and rotation speed.

[0038] The penetration speed and withdrawal speed of rods 21 and 22 are preferably controlled to be 0.3 to 1.0 m / min, and the rotation speed of rods 21 and 22 (the rotation speed of stirring blades 211 and 221) is preferably controlled to be 30 to 60 rpm. However, these penetration speeds, withdrawal speeds, and rotation speeds are merely examples of typical numerical ranges, and are not limited to these numerical ranges.

[0039] If a high-pressure injection method (high-pressure injection mixing method) is adopted as the deep mixing method instead of the mechanical mixing method, the mixer 20 described above can be replaced with a mixer designed for the high-pressure injection method. A mixer for the high-pressure injection method includes a rod that penetrates deep ground. A nozzle is provided on the side wall near the tip of the rod to horizontally inject fluids such as carbonaceous material-containing slurry, hardener slurry, and water. The rod is configured to rotate around its central axis while injecting fluids at high pressure. This allows the fluid to be mixed in situ with the deep ground soil while cutting the deep ground. Depending on the type of fluid injected from the nozzle, there are several types of rods, such as single-pipe, double-pipe, and triple-pipe types. When a single-pipe rod is used, a carbonaceous material-mixed hardener slurry is injected as the fluid. When a double-tube rod is used, the carbonaceous material-containing hardener slurry and air are supplied separately to the nozzle, and the carbonaceous material-containing hardener slurry accompanied by the air flow is sprayed as a fluid. When a triple-tube rod is used, (1) water and air are supplied separately to the first nozzle, and the water accompanied by the air flow is sprayed as a fluid, and (2) the carbonaceous material-containing hardener slurry is supplied to the second nozzle, and the carbonaceous material-containing hardener slurry is sprayed as a fluid. Note that carbonaceous material slurry may be used instead of water, and the carbonaceous material slurry accompanied by the air flow may be sprayed from the first nozzle. In this case, the fluid sprayed from the second nozzle may be a hardener slurry that does not contain carbonaceous material. Note that in the high-pressure injection method, the pressure of the pump P that pumps the slurry (carbonaceous material-containing slurry or hardener slurry) is very high compared to the mechanical stirring method. The pressure at which the slurry is pumped varies depending on the type of high-pressure injection method and ranges widely, for example, from about 2 MPa to about 40 MPa. Therefore, the pressure of the pump P applied to the slurry is not limited, and can be appropriately selected depending on the type of the rod, etc.

[0040] <Deep ground improvement method> The mechanical mixing method performed using the deep soil improvement machine 100 will be described with reference to Figs. 3 to 6. Fig. 3 is a schematic diagram illustrating the mechanical mixing method in which a carbon material-mixed hardening material slurry SR1 is discharged on the return path. Fig. 4 is a schematic diagram illustrating the mechanical mixing method in which a carbon material-mixed hardening material slurry SR1 is discharged on the forward path. Fig. 5 is a schematic diagram illustrating the mechanical mixing method in which a carbon material-mixed hardening material slurry SR1 is discharged on both the forward path and the return path. Fig. 6 is a schematic diagram illustrating the mechanical mixing method in which a carbon material slurry SR2 is discharged on the forward path and a hardening material slurry SR3 is discharged on the return path.

[0041] The mechanical mixing method according to one embodiment of the present invention includes a discharging step and an in-situ mixing step. The discharging step is a step of discharging a carbonaceous material-containing slurry into deep ground G using a deep ground improvement machine 100, and the in-situ mixing step is a step of mixing the carbonaceous material-containing slurry discharged into the deep ground G with the deep ground G in-situ using the deep ground improvement machine 100. Here, the carbonaceous material-containing slurry may be a carbonaceous material slurry or a carbonaceous material-mixed hardening material slurry.

[0042] When the carbonaceous material-containing slurry is a carbonaceous material slurry, a hardening material slurry is discharged into the deep ground G at a timing different from the timing of discharging the carbonaceous material slurry in order to harden the deep ground G. In other words, the discharging step is carried out on either the outward path where the pipe and the stirring blade are inserted into the deep ground G or the return path where the pipe and the stirring blade are pulled out from the deep ground G, and the in-situ mixing step is carried out after or before the discharging step is carried out, or simultaneously with the discharging step.

[0043] Furthermore, when the carbonaceous material-containing slurry is a carbonaceous material-mixed hardening material slurry, the hardening material is contained in the carbonaceous material-mixed hardening material slurry. Therefore, in this case, the hardening material slurry may or may not be discharged into the deep ground G at a timing different from the timing of discharging the carbonaceous material-mixed hardening material slurry. In other words, the discharging step is performed on either or both of the forward and return paths, and the in-situ mixing step is performed after the discharging step is performed or simultaneously with the discharging step.

[0044] First, a specific example will be described in which a carbonaceous material-mixed hardening material slurry SR1 is used as the carbonaceous material-containing slurry. In the mixer 20, on the outward journey, as shown in Fig. 3(a), the rods 21 and 22 are rotated forward to cause the agitating blades 211 and 221 to penetrate into the ground G. At this time, the slurry is not discharged from the first discharge ports 213 and 223 and the second discharge port 231, and the tips of the rods 21 and 22 are allowed to reach the design improvement depth, as shown in Fig. 3(b). Next, on the return journey, as shown in Fig. 3(c), the rods 21 and 22 are rotated backward to cause the agitating blades 211 and 221 to be withdrawn from the ground G. At this time, the carbonaceous material-mixed hardening material slurry SR1 is discharged from the second discharge port 231, and the slurry is not discharged from the first discharge ports 213 and 223. As shown in Fig. 3(d), the tips of the rods 21 and 22 are allowed to reach the water bottom. This allows the rotation of the agitator blades 211, 221 to mix in situ the soil contained in the ground G with the carbonaceous material-mixed hardening material slurry SR1 discharged on the return trip. The soil, carbonaceous material, and hardening material mixed in situ harden, allowing a cylindrical improved pile (improved body) 50 with an improved top on the water bottom surface and fixed carbon to be constructed from the designed improvement depth. As mentioned above, the carbonaceous material-mixed hardening material slurry SR1 containing carbonaceous material discharged from the second discharge port 231 may contain air bubbles.

[0045] 4(a), the mixing treatment machine 20 may cause the rods 21 and 22 to rotate in the forward direction to penetrate the mixing blades 211 and 221 into the ground G, and discharge the carbon material mixed hardening material slurry SR1 from the first discharge ports 213 and 223 without discharging the slurry from the second discharge port 231, and may cause the tips of the rods 21 and 22 to reach the design improvement depth as shown in FIG. 4(b). Next, on the return path, the rods 21 and 22 may cause the rods 21 and 22 to rotate in the reverse direction to pull the mixing blades 211 and 221 out of the ground G, and may cause the tips of the rods 21 and 221 to reach the water bottom as shown in FIG. 4(d). This allows the rotation of the agitator blades 211, 221 to mix the clay contained in the ground G with the carbonaceous material-mixed hardening material slurry SR1 discharged on the outward journey. As the clay, carbonaceous material, and hardening material mixed in situ harden, a cylindrical improved pile (improved body) 50 with an improved top on the water bottom surface and fixed carbon can be constructed from the designed improvement depth. Note that the carbonaceous material-mixed hardening material slurry SR1 containing carbonaceous material discharged from the first discharge outlets 213, 223 may contain air bubbles, as described above.

[0046] 5(a), the mixing processor 20 may rotate the rods 21 and 22 in the forward direction to cause the agitating blades 211 and 221 to penetrate into the ground G, at which time the carbonaceous material-mixed hardening material slurry SR1 is discharged from the first discharge ports 213 and 223, without discharging the slurry from the second discharge port 231, and may allow the tips of the rods 21 and 22 to reach the design improvement depth, as shown in FIG. 5(b). Next, on the return path, as shown in FIG. 5(c), the mixing processor 20 may rotate the rods 21 and 22 in the reverse direction to pull the agitating blades 211 and 221 out of the ground G, at which time the carbonaceous material-mixed hardening material slurry SR1 is discharged from the second discharge port 231, without discharging the slurry from the first discharge port 213 and 223, and may allow the tips of the rods 21 and 22 to reach the water bottom. This allows the rotation of the agitator blades 211, 221 to mix the soil and sand contained in the ground G with the carbonaceous material-mixed hardening material slurry SR1 discharged on both the outbound and return passes. The soil and sand, carbonaceous material, and hardening material mixed in situ harden, allowing a cylindrical improved pile (improved body) 50 with an improved top on the water bottom surface and fixed carbon to be constructed from the designed improvement depth. As mentioned above, the carbonaceous material-mixed hardening material slurry SR1 discharged from the first discharge outlets 213, 223 and the second discharge outlet 231 may contain air bubbles.

[0047] By repeatedly performing the mechanical mixing method shown in any one of FIGS. 3 to 5, deep ground improvement of the ground G can be carried out over a wide area.

[0048] Next, a specific description will be given of a case where the carbon material slurry SR2 is used as the carbon material-containing slurry. When the carbon material slurry SR2 and the hardening material slurry SR3 are supplied separately to the ground G, the carbon material slurry SR2 is discharged onto the ground G on the outward journey, and the hardening material slurry SR3 is discharged onto the ground G on the return journey.

[0049] 6(a), on the way out, the mixing treatment machine 20 rotates the rods 21, 22 in the forward direction to cause the mixing blades 211, 221 to penetrate into the ground G, and at this time, the carbon material slurry SR2 is discharged from the first discharge ports 213, 223, and no slurry is discharged from the second discharge ports 231, and the tips of the rods 21, 22 can be made to reach the design improvement depth, as shown in FIG. 6(b). Next, on the way back, as shown in FIG. 6(c), the rods 21, 22 are rotated in the reverse direction to pull the mixing blades 211, 221 out of the ground G, and at this time, the hardening material slurry SR3 is discharged from the second discharge ports 231, and no slurry is discharged from the first discharge ports 213, 223, and the tips of the rods 21, 22 can be made to reach the water bottom, as shown in FIG. 6(d). As a result, the rotation of the agitator blades 211, 221 can mix the clay contained in the ground G with the carbon material slurry SR2 discharged on the outbound path and the hardening material slurry SR3 discharged on the return path. By hardening the clay, carbon material, and hardening material mixed in situ, a cylindrical improved pile (ground improvement body) 50 with an improved top end on the water bottom surface and fixed carbon can be constructed from the designed improvement depth. As described above, the carbon material slurry SR2 discharged from the first discharge outlets 213, 223 and the hardening material slurry SR3 discharged from the second discharge outlet 231 may contain air bubbles. Alternatively, the carbon material-mixed hardening material slurry SR1 used in the first embodiment may be discharged instead of the hardening material slurry SR3 discharged from the second discharge outlet 231. The slurry discharged onto the ground G on the outbound path and the slurry discharged onto the ground G on the return path may be interchanged. That is, the mixer 20 may be configured to discharge the hardening material slurry SR3 on the outward path and discharge the carbon material slurry SR2 on the return path. By repeatedly performing the mechanical mixing method shown in Figure 6, deep ground improvement of the ground G can be carried out over a wide area.

[0050] Second Embodiment <Method for producing carbon material mixed hardener slurry> In this embodiment, a method for producing a carbonaceous material-mixed hardener slurry will be described. The carbonaceous material-mixed hardener slurry is a slurry containing at least water, a carbonaceous material, and a hardener. This production method includes a mixing step of mixing water, the carbonaceous material, and the hardener.

[0051] The present manufacturing method may further include a carbonaceous material selection step performed before the mixing step, in which the carbonaceous material is selected by sieving the carbonaceous material. In this case, the mixing step includes mixing the carbonaceous material that has passed through the sieve in the carbonaceous material selection step with water and the curing agent.

[0052] The present manufacturing method may further include an air bubble mixing step of mixing air bubbles into the water or carbonaceous material mixed hardener slurry. Mixing air bubbles improves the fluidity of the carbonaceous material-containing slurry, but air bubbles smaller than 0.1 mm tend to impair fluidity, while air bubbles larger than 1.0 mm tend to impair fluidity and break easily. Therefore, the air bubble size is preferably 0.1 mm or more and 1.0 mm or less in diameter. The air bubble diameter referred to here is the average diameter. The air bubble diameter can be measured, for example, by laser diffraction / scattering. In the air bubble mixing step, it is preferable to generate air bubbles derived from exhaust gas emitted from a construction machine and mix the air bubbles into the water or carbonaceous material mixed hardener slurry.

[0053] In the mixing step of the present production method, an admixture may be further mixed in addition to the water, the carbon material, and the hardening material. That is, the carbon material-mixed hardening material slurry may further contain an admixture in addition to the water, the carbon material, and the hardening material.

[0054] From the viewpoint of stabilizing the fluidity of the carbonaceous material-containing hardener slurry and preventing separation of the carbonaceous material, the weight of water mixed with the carbonaceous material-containing hardener slurry is adjusted to 50% to 100%, preferably 80% to 100%, based on the weight of the hardener contained in the carbonaceous material-containing hardener slurry being 100%. This can impart appropriate viscosity to the carbonaceous material-containing hardener slurry and ensure the fluidity of the carbonaceous material-containing hardener slurry within a rod (pipe) for supplying it to deep ground. Furthermore, separation of the carbonaceous material when the carbonaceous material-containing hardener slurry is mixed with the carbonaceous material can be prevented. The water used to produce the carbonaceous material-containing hardener slurry is not limited and may be freshwater, brackish water, or seawater.

[0055] From the viewpoint of maintaining the fluidity of the carbonaceous material-mixed hardener slurry and preventing separation of the carbonaceous material, the viscosity of the hardener slurry is measured using a rotational viscometer (VG meter) and is preferably 10 mPa·s or more and 100 mPa·s or less under ambient air conditions.

[0056] The hardener contained in the carbonaceous material-mixed hardener slurry is typically cement, and may be Portland cement, blast furnace cement containing blast furnace slag, or fly ash cement. The hardener may also be a neutral hardener containing magnesium oxide and an acidic hardening aid such as aluminum sulfate.

[0057] The carbonaceous material-mixed hardener slurry may contain admixtures such as a thickener, a high-performance water-reducing agent, a high-performance air-entraining water-reducing agent, and a superplasticizer, thereby adjusting the viscosity of the hardener slurry. The hardener slurry may also contain fine aggregate.

[0058] <Carbon materials> From the viewpoint of carbon neutrality, the carbon material is preferably biochar made from plants or plant-derived materials. Examples of biochar include bamboo charcoal, wood charcoal, and rice husk charcoal. The biochar is preferably bamboo charcoal. Bamboo, the material used to make bamboo charcoal, grows faster than other plants, which can speed up the cycle of bamboo forest harvesting, bamboo charcoal production, and bamboo forest regeneration. Therefore, using bamboo charcoal as the carbon material allows for efficient production of the carbon material. Furthermore, from a different perspective than carbon neutrality, the specific surface area of ​​bamboo charcoal is larger than that of rice husk charcoal. Therefore, bamboo charcoal has higher adsorption performance than rice husk charcoal. The inclusion of a carbon material in the improvement body can improve the water retention and heavy metal adsorption properties of the ground G.

[0059] The carbon material mentioned above has an apparent specific gravity of 0.4 g / cm 3 The specific gravity is small. Therefore, when water, a carbonaceous material, and a hardener are simply mixed, the carbonaceous material and the hardener slurry are separated due to the difference in specific gravity between them, as shown in FIG. 7(a), and the separated carbonaceous material tends to float in the hardener slurry. When the carbonaceous material adsorbs hardener particles, the apparent specific gravity increases. However, if the apparent specific gravity becomes too large, the carbonaceous material tends to settle in the hardener slurry, as shown in FIG. 7(b). As shown in FIG. 7(c), it is preferable that the carbonaceous material does not separate in the carbonaceous material-mixed hardener slurry and is dispersed substantially uniformly in the carbonaceous material-mixed hardener slurry. The uniform dispersion of the carbonaceous material can stabilize the fluidity of the carbonaceous material-mixed hardener slurry.

[0060] From the viewpoint of preventing separation of the carbonaceous material due to floating or settling and stabilizing the fluidity of the carbonaceous material-mixed hardener slurry, it is preferable to crush the carbonaceous material in advance so that it can pass through a sieve with 2 mm openings. This facilitates uniform dispersion of the carbonaceous material in the carbonaceous material-mixed hardener slurry and prevents clogging of the first discharge ports 213, 223 and the second discharge port 231 provided on the pair of rods 21, 22. It is preferable to use a sieve with a nominal opening of 2 mm conforming to JIS Z8801-1. Carbonaceous material that passes through a sieve with 2 mm openings can have an average particle size (D50) of approximately 1 mm. The particle size of the carbonaceous material can be measured, for example, by laser diffraction / scattering.

[0061] The carbon material may be pulverized using a pulverizer such as a hammer mill or a roller mill.

[0062] The carbon material is a mixture of the hardener and water contained in the carbon-mixed hardener slurry. 3 It is preferable to mix the carbon material so that the amount is 150 kg or more and 300 kg or less per unit area. By making the amount of carbon material contained in the carbon material mixed hardener slurry 150 kg or more, the balance between the amount of carbon dioxide emitted and absorbed by the construction machinery, etc. used in the construction work can be made substantially zero or less. Furthermore, by mixing the amount of carbon material contained in the carbon material mixed hardener slurry so that the amount is 300 kg or less, the fluidity of the carbon material mixed hardener slurry containing the carbon material can be improved when it is supplied to a deep layer through a pipe. The balance between the amount of carbon dioxide emitted and absorbed in the carbon material mixed hardener slurry is calculated as shown in Table 1 below. In the experimental cases shown in Table 1, BB is an abbreviation for blast furnace cement, and CH is an abbreviation for carbon material. Furthermore, the numbers (25 and 50) attached to CH are the carbon dioxide emitted per 1 m of improved body. 3 Weight of carbon material per unit (unit: kg / m 3 ) [Table 1]

[0063] (bubbles) The carbonaceous material mixed hardener slurry may further contain air bubbles. By mixing air bubbles into the carbonaceous material mixed hardener slurry, the fluidity of the carbonaceous material mixed hardener slurry can be increased. Air bubbles can be produced by mixing a diluent such as water, a foaming agent, and compressed air, and the produced air bubbles can be mixed into the carbonaceous material mixed hardener slurry containing the carbonaceous material. An admixture may also be mixed into the carbonaceous material mixed hardener slurry. Examples of admixtures include thickeners, high-performance water reducers, high-performance air-entraining water reducers, and superplasticizers.

[0064] Third Embodiment <Method for producing carbon material slurry> In this embodiment, a method for producing a carbonaceous material slurry will be described. The carbonaceous material slurry is a slurry containing at least water and a carbonaceous material. This production method includes a mixing step of mixing the water and the carbonaceous material.

[0065] The present manufacturing method may further include a carbonaceous material selection step performed before the mixing step, in which the carbonaceous material is selected by sieving the carbonaceous material. In this case, the mixing step includes mixing the carbonaceous material that has passed through the sieve in the carbonaceous material selection step with water and a curing agent.

[0066] The present manufacturing method may further include a bubble-mixing step of mixing bubbles into the water or carbon material slurry. In this case, the size of the bubbles is preferably 0.1 mm or more and 1.0 mm or less in diameter. If the size of the bubbles is smaller than 0.1 mm, the fluidity is easily impaired, and if the size of the bubbles is larger than 1.0 mm, the fluidity is impaired and the bubbles are easily broken.

[0067] The bubble diameter referred to here is an average diameter. The bubble diameter can be measured, for example, by laser diffraction / scattering. In the bubble mixing step, it is preferable to generate bubbles derived from exhaust gas emitted from a construction machine and mix the bubbles into the water or carbon material slurry.

[0068] In the mixing step of the present production method, in addition to the water and the carbonaceous material, an admixture may be further mixed in. That is, the carbonaceous material slurry may further contain an admixture in addition to the water and the carbonaceous material.

[0069] Unlike the carbonaceous material mixed hardener slurry, the carbonaceous material slurry does not contain a hardener. Therefore, the fluidity of the carbonaceous material slurry is likely to be higher than that of the carbonaceous material mixed hardener slurry. Therefore, the carbonaceous material slurry can contain more carbonaceous material than the carbonaceous material mixed hardener slurry. The amount of carbonaceous material contained in the produced carbonaceous material slurry is not limited, and can be determined appropriately within a range that does not clog the pipe when it is pumped to the ground G using a pipe.

[0070] The carbon material contained in the carbon material slurry can be the same as the carbon material contained in the carbon material mixed hardener slurry. The carbon material is preferably selected by passing it through a sieve with a predetermined mesh size. The carbon material is preferably crushed in advance so that it can easily pass through the sieve.

[0071] The mixing ratio of water and hardener in the hardener slurry that is discharged into the deep ground separately from the carbon material slurry is not limited, and can be appropriately determined within a range that does not clog the pipe when it is pumped into the ground G using a pipe. The hardener slurry may also contain the above-mentioned air bubbles and admixtures.

[0072] [Additional Notes] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0073] 〔summary〕 A method for producing a carbonaceous material-containing slurry according to a first aspect of the present invention is a method for producing a carbonaceous material-containing slurry to be discharged into deep ground. In this production method, the carbonaceous material-containing slurry contains at least water and a carbonaceous material. The production method includes a mixing step of mixing the water and the carbonaceous material.

[0074] Carbonaceous materials, which are materials made from charcoal, are biochars obtained by carbonizing plants such as wood and bamboo, or plant-derived materials such as rice husks. By using biochar, it is possible to fix more carbon dioxide in the carbonaceous material than is generated when carbonizing plant-derived materials. Plants grow by photosynthesis. Therefore, carbonaceous materials obtained from plants or plant-derived materials can be considered materials that absorb carbon dioxide.

[0075] The carbonaceous material-containing slurry obtained by the first aspect of the present invention contains carbonaceous material that has absorbed carbon dioxide during the growth process. Therefore, according to the above configuration, by discharging the carbonaceous material-containing slurry into deep ground, carbon dioxide can be fixed in the deep ground.

[0076] Furthermore, in addition to the configuration of the method for producing a carbonaceous material-containing slurry according to the second aspect of the present invention, the method further includes a carbonaceous material selection step carried out before the mixing step, in which the carbonaceous material is selected by sieving the carbonaceous material, and the mixing step employs a configuration in which the carbonaceous material that has passed through the sieve in the carbonaceous material selection step is mixed with the water.

[0077] When the carbonaceous material-containing slurry obtained by the method for producing a carbonaceous material-containing slurry according to the second aspect of the present invention is discharged into deep ground, a pipe is installed between the ground and the original position, and the carbonaceous material-containing slurry is pumped through the pipe. According to the second aspect, the carbonaceous material is sieved in advance to a predetermined size, which reduces the possibility of the pipe becoming clogged during the pumping process. The mesh size of the sieve can be determined appropriately depending on the inner diameter of the pipe, the viscosity of the carbonaceous material-containing slurry to be produced, and the like.

[0078] Furthermore, in the method for producing a carbonaceous material-containing slurry according to a third aspect of the present invention, in addition to the configuration of the method for producing a carbonaceous material-containing slurry according to the first or second aspect described above, a configuration is adopted which further includes an air bubble mixing step of mixing air bubbles into water or the carbonaceous material-containing slurry.

[0079] The carbonaceous material-containing slurry produced has air bubbles mixed therein, which can increase the fluidity of the carbonaceous material-containing slurry. Therefore, the above configuration can reduce the possibility of clogging a pipe during the process of pumping the carbonaceous material-containing slurry through the pipe.

[0080] Furthermore, in the method for producing a carbonaceous material-containing slurry according to a fourth aspect of the present invention, in addition to the configuration of the method for producing a carbonaceous material-containing slurry according to the third aspect described above, a configuration is adopted in which the size of the bubbles has a diameter of 0.1 mm or more and 1.0 mm or less.

[0081] If the size of the bubbles is less than 0.1 mm in diameter, the problem of fluidity being easily impaired is likely to occur. Furthermore, if the size of the bubbles is more than 1.0 mm in diameter, not only is the fluidity easily impaired but the bubbles are also likely to break. Therefore, according to the above configuration, a carbonaceous material-containing slurry having improved fluidity without breaking bubbles can be obtained.

[0082] Furthermore, in the method for producing a carbonaceous material-containing slurry according to the fifth aspect of the present invention, in addition to the configuration of the method for producing a carbonaceous material-containing slurry according to the third aspect described above, the air bubble mixing step generates air bubbles derived from exhaust gas emitted from a construction machine and mixes the air bubbles into water or the carbonaceous material-containing slurry.

[0083] The exhaust gas emitted from a construction machine contains carbon dioxide because it is exhaust gas emitted from the internal combustion engine equipped in the construction machine. Therefore, according to the above configuration, by discharging the carbonaceous material-containing slurry mixed with the exhaust gas into deep ground, the amount of carbon dioxide fixed in the deep ground can be further increased.

[0084] Furthermore, in the method for producing a carbonaceous material-containing slurry according to a sixth aspect of the present invention, in addition to the configuration of the method for producing a carbonaceous material-containing slurry according to any one of the first to fifth aspects described above, the carbonaceous material-containing slurry further contains a hardening agent, and the mixing step mixes water, the carbonaceous material, and the hardening agent.

[0085] According to the above configuration, by discharging the carbon material into the deep ground simultaneously with the hardening material, it is possible to improve the ground and fix carbon dioxide at the same time.

[0086] Furthermore, in the method for producing a carbonaceous material-containing slurry according to a seventh aspect of the present invention, in addition to the configuration of the method for producing a carbonaceous material-containing slurry according to the sixth aspect described above, a configuration is adopted in which the weight of water used in the mixing step is 50% or more and 100% or less of the weight of the hardening material.

[0087] According to the above configuration, it is possible to impart appropriate viscosity to the carbonaceous material-containing slurry containing the hardening agent, thereby ensuring the fluidity of the carbonaceous material-containing slurry in a pipe for pumping it to deep ground. Also, it is possible to reduce separation of the carbonaceous material from the water and hardening agent. Therefore, according to the above configuration, it is possible to reduce separation of the carbonaceous material from the water and hardening agent while ensuring the fluidity of the carbonaceous material-containing slurry.

[0088] Furthermore, in the method for producing a carbonaceous material-containing slurry according to an eighth aspect of the present invention, in addition to the configuration of the method for producing a carbonaceous material-containing slurry according to the sixth or seventh aspect described above, the weight of the carbonized material used in the mixing step is 150 kg / m with respect to the volume of the carbonaceous material-containing slurry. 3 More than 300kg / m 3 The following configuration is adopted:

[0089] The amount of carbon material contained in the carbon material-containing slurry is 150 kg / m 3 By doing so, the balance between the amount of carbon dioxide emitted and absorbed by construction machinery and the like used in the construction work can be made substantially equal to or less than zero. Furthermore, by mixing the carbonaceous material contained in the carbonaceous material-containing slurry so that the amount of carbonaceous material is 300 kg or less, excessive reduction in fluidity can be suppressed. As a result, the possibility of the carbonaceous material-containing slurry clogging a pipe when pumped through a pipe can be reduced. Therefore, with the above configuration, the balance between the amount of carbon dioxide emitted and absorbed can be made substantially equal to or less than zero, while reducing the possibility of the pipe clogging during pumping.

[0090] Furthermore, in a method for producing a carbonaceous material-containing slurry according to a ninth aspect of the present invention, in addition to the configuration of the method for producing a carbonaceous material-containing slurry according to any one of the sixth to eighth aspects described above, a configuration is adopted in which the viscosity of the carbonaceous material-containing slurry is 10 mPa·s or more and 100 mPa·s or less at 20°C.

[0091] The above configuration provides the same effect as the carbonaceous material-containing slurry according to the seventh aspect, that is, it is possible to reduce separation of the carbonaceous material from the water and the hardening agent while ensuring the fluidity of the carbonaceous material-containing slurry.

[0092] Furthermore, in the method for producing a carbonaceous material-containing slurry according to a tenth aspect of the present invention, in addition to the configuration of the method for producing a carbonaceous material-containing slurry according to any one of the sixth to ninth aspects described above, a configuration is adopted in which an admixture is further mixed in the mixing step.

[0093] According to the above configuration, various properties, such as the viscosity of the carbonaceous material-containing slurry, can be adjusted by adjusting the type and amount of the admixture to be added, etc. Examples of the admixture include a thickener, a high-performance water-reducing agent, a high-performance air-entraining water-reducing agent, and a superplasticizer.

[0094] The deep ground improvement method according to the eleventh aspect of the present invention includes a discharging step and an in-situ mixing step as described in the first embodiment. In this deep ground improvement method, the discharging step is a step of discharging, into the deep ground, a carbonaceous material-containing slurry produced by the carbonaceous material-containing slurry production method described in the second and third embodiments of the present invention using a deep ground improvement machine, and the in-situ mixing step is a step of mixing, in-situ, the carbonaceous material-containing slurry discharged into the deep ground with the deep ground using the deep ground improvement machine.

[0095] According to the above configuration, deep soil improvement can be carried out and carbon dioxide can be fixed in the deep soil using the carbonaceous material-containing slurry.

[0096] Furthermore, in the deep ground improvement method according to the twelfth aspect of the present invention, in addition to the configuration of the deep ground improvement method according to the eleventh aspect described above, the carbonaceous material-containing slurry contains at least water and carbonaceous material, the deep ground improvement machine is equipped with a pipe having a discharge port formed at its tip for discharging the carbonaceous material-containing slurry into the deep ground, and an agitator blade for mixing the carbonaceous material-containing slurry with the deep ground in situ, the discharge process being carried out on either the outbound path in which the pipe and agitator blade are inserted into the deep ground, or the return path in which the pipe and agitator blade are withdrawn from the deep ground, and the in situ mixing process being carried out after the discharge process has been carried out or simultaneously with the discharge process.

[0097] According to the above configuration, cylindrical improvement piles (ground improvement bodies) in which carbon is reliably fixed in the deep ground can be constructed from the design improvement depth.

[0098] Furthermore, in the deep ground improvement method according to the thirteenth aspect of the present invention, in addition to the configuration of the deep ground improvement method according to the eleventh aspect described above, the carbonaceous material-containing slurry contains at least water, carbonaceous material, and hardening material, the deep ground improvement machine is equipped with a pipe having a discharge port formed at its tip for discharging the carbonaceous material-containing slurry into the deep ground, and an agitator blade for mixing the carbonaceous material-containing slurry with the deep ground in situ, the discharge process is carried out on either or both of the outbound path in which the pipe and agitator blade are inserted into the deep ground, and the return path in which the pipe and agitator blade are withdrawn from the deep ground, and the in situ mixing process is carried out after the discharge process is carried out or simultaneously with the discharge process.

[0099] According to the above configuration, cylindrical improvement piles (ground improvement bodies) in which carbon is reliably fixed in the deep ground can be constructed from the design improvement depth.

[0100] Although the embodiments for carrying out the present invention have been described above, the present invention is not limited to these, and various modifications are possible within the scope of the technical concept of the present invention. For example, in the deep soil improvement machine 100 described in this embodiment 1, the same carbon material-mixed hardening material slurry SR1, carbon material slurry SR2, or hardening material slurry is ejected into the deep ground from both the rods 21 and 22 on the outbound and return journeys. However, the carbon material-mixed hardening material slurry SR1 may be ejected from the rod 21 and the carbon material slurry SR2 may be ejected from the rod 22. Alternatively, the hardening material slurry may be ejected from the rod 21 on both the outbound and return journeys, and the carbon material-mixed hardening material slurry SR1 or the carbon material slurry SR2 may be ejected from the rod 22. This makes it unnecessary to limit the ejection time of the carbon material slurry. [Industrial Applicability]

[0101] The present invention can be used for underground fixation of carbon dioxide in deep ground improvement. [Explanation of symbols]

[0102] 10. Slurry Plant 11 Measurement section 12 Mixer 13 Flow meter 14 Agitator 15 Foaming machine 20 Mixing machine 21, 22 Rod (pipe) 211, 211a, 211b, 211c stirring blade 221, 221a, 221b, 221c stirring blade 213, 223 1st discharge port 214, 224 Bearings 23 Fixed discharge pipe 231 2nd outlet 100 Deep soil improvement machine G Ground (deep ground)

Claims

1. A method for producing a carbonaceous material-containing slurry to be discharged into deep ground, the carbonaceous material-containing slurry contains at least water and a carbonaceous material, A method for producing a carbonaceous material-containing slurry, comprising a mixing step of mixing the water and the carbonaceous material.

2. The method further includes a carbon material sorting step performed before the mixing step, in which the carbon material is sorted by sieving the carbon material; The method for producing a carbonaceous material-containing slurry according to claim 1 , wherein the mixing step comprises mixing the carbonaceous material that has passed through the sieve in the carbonaceous material sorting step with the water.

3. The method for producing a carbonaceous material-containing slurry according to claim 1 or 2, further comprising an air bubble mixing step of mixing air bubbles into the water or the carbonaceous material-containing slurry.

4. The method for producing a carbonaceous material-containing slurry according to claim 3 , wherein the bubbles have a diameter of 0.1 mm or more and 1.0 mm or less.

5. 4. The method for producing a carbonaceous material-containing slurry according to claim 3, wherein the air bubble mixing step generates the air bubbles derived from exhaust gas discharged from a construction machine and mixes the air bubbles into the water or the carbonaceous material-containing slurry.

6. The carbonaceous material-containing slurry further comprises a hardening material, The method for producing a carbonaceous material-containing slurry according to claim 1 or 2, wherein the mixing step includes mixing the water, the carbonaceous material, and the hardening material.

7. The method for producing a carbonaceous material-containing slurry according to claim 6, wherein a weight of water used in the mixing step is 50% or more and 100% or less of a weight of the hardening material.

8. The weight of the carbonized material used in the mixing step is 150 kg / m relative to the volume of the carbon material-containing slurry. ３ More than 300kg / m ３ The method for producing a carbonaceous material-containing slurry according to claim 6, wherein:

9. 7. The method for producing a carbonaceous material-containing slurry according to claim 6, wherein the carbonaceous material-containing slurry has a viscosity of 10 mPa·s or more and 100 mPa·s or less at 20°C.

10. The method for producing a carbonaceous material-containing slurry according to claim 6 , wherein an admixture is further mixed in the mixing step.

11. A discharge step of discharging the carbonaceous material-containing slurry produced by the method for producing a carbonaceous material-containing slurry according to claim 1 into deep ground using a deep soil improvement machine; A deep ground improvement method comprising: an in-situ mixing step of mixing the carbonaceous material-containing slurry discharged into the deep ground with the deep ground using the deep ground improvement machine.

12. the carbonaceous material-containing slurry contains at least water and a carbonaceous material, The deep soil improvement machine includes a pipe having a discharge port formed at its tip for discharging the carbonaceous material-containing slurry into the deep ground, and a stirring blade for mixing the carbonaceous material-containing slurry and the deep ground at the in situ; The discharge step is carried out on either the outward path of penetrating the pipe and the stirring blade into the deep ground or the return path of withdrawing the pipe and the stirring blade from the deep ground; The deep soil improvement method according to claim 11, wherein the in-situ mixing step is carried out after the discharging step is carried out or simultaneously with the discharging step.

13. the carbonaceous material-containing slurry contains at least water, a carbonaceous material, and a hardening material; The deep soil improvement machine includes a pipe having a discharge port formed at its tip for discharging the carbonaceous material-containing slurry into the deep ground, and a stirring blade for mixing the carbonaceous material-containing slurry and the deep ground at the in situ; The discharge step is carried out in either one or both of the forward path of penetrating the pipe and the stirring blade into the deep ground and the return path of withdrawing the pipe and the stirring blade from the deep ground; The deep soil improvement method according to claim 11, wherein the in-situ mixing step is carried out after the discharging step is carried out or simultaneously with the discharging step.

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