Analysis method, evaluation method, and analysis program for carbon dioxide fixation filler

Abstract

To provide a method for evaluating carbon dioxide fixation filler suitable as a technique for evaluating the long-term durability of carbon dioxide fixation filler to be placed in abandoned tunnels of closed and abandoned mines, and to provide an analysis method and analysis program applicable to said evaluation method. [Solution] One aspect of the present invention is a method for analyzing carbon dioxide fixation filler, which is a method for evaluating filler placed in an underground space, in which the filler is a carbon dioxide fixation material containing carbonate produced by reacting a starting material with carbon dioxide, and the method acquires physical quantities indicating the quality of the groundwater present in the target underground space, the temperature and depth of the underground space, the amount of carbonate contained in the filler, the dissolution rate of the filler in groundwater, the specific surface area of ​​the filler, and the ratio of the amount of groundwater inflowing into contact with the filler to the amount of filler, and analyzes changes in the amount of carbon dioxide fixation by the filler over time based on the acquired physical quantities, temperature and depth, amount of substance, dissolution rate, specific surface area, and ratio.

Description

[Technical Field]

[0001] The present invention relates to an analysis method, an evaluation method, and an analysis program for a carbon dioxide fixing filler (a filler containing a carbonate produced by reacting a starting material with carbon dioxide). [Background technology]

[0002] As the world moves away from dependence on fossil fuels, Japan plans to gradually shut down its thermal power plants rather than immediately shutting them down. Carbon dioxide Capture and Storage (CCS) is seen as an effective measure to combat CO2 emissions in the interim, and the Energy Supply Structure Enhancement Act also legally defines thermal power plants with CCS as zero emissions. The Ministry of Economy, Trade and Industry (METI) has set an intermediate goal of installing CCS sites with an annual capacity of 6 to 12 million tons by 2030, and a final goal of over 100 million tons per year by 2050, with nine sites in Japan already selected for advanced CCS projects. The CCS Business Act has also been enacted, and full-scale implementation is expected.

[0003] The storage potential of each site is estimated to be between 1.4 million tons and 3 million tons per year, and all are located offshore. To achieve the final target of 2050, approximately 10 million tons per year will be needed, and CO2 injection wells will be added at a rate of approximately 10 wells per year. However, there are many issues specific to offshore areas, such as cost, consistency with the Marine Pollution Control Act and the Basic Act on Ocean Policy, understanding and consensus building among residents, and active faults.

[0004] On the other hand, existing advanced CCS projects do not include land areas. However, considering the transportation costs from CO2 capture to injection, the convenience of infrastructure, ease of monitoring, and the fact that many CO2 emission sources, not just thermal power plants with CCS but also steelworks, are on land, small-scale, inexpensive CO2 fixation on land is effective, and this is seen as a societal demand, so efforts to develop original technologies are increasing.

[0005] One possible use of space for terrestrial CO2 fixation is the abandoned mine tunnels of closed mines both in Japan and overseas. In particular, there are 74 mines in Japan that require mine wastewater treatment, and more than 2 billion yen is spent annually on mine wastewater treatment subsidies alone.

[0006] Therefore, the Ministry of Economy, Trade and Industry has clearly stated in its "Basic Policy for the Implementation of Pollution Prevention Projects for Specified Facilities No. 6" that it will newly consider contributing to carbon neutrality, complete mine wastewater treatment, accelerate cost reductions, and address the reduction of the volume of neutralized sediment. By developing low-carbon materials based on this neutralized sediment (materials with low CO2 emissions during the manufacturing process, materials that store CO2 within the material during manufacturing, etc.) and filling them into mine tunnels as carbon dioxide fixation filler, it will be possible to reduce mine wastewater treatment costs, reduce the volume of neutralized sediment, and contribute to the realization of carbon neutrality.

[0007] Furthermore, the following is stated in Patent Document 1: With the rapid progress of global warming in recent years, there is a demand for the practical application of carbon capture, storage, and utilization (CCSU) technology, which fixes emitted carbon dioxide in minerals, in addition to reducing the amount of carbon dioxide emitted.

[0008] One carbon sequestration and utilization technology (CCSU) that has attracted attention is the technology of reacting silicate minerals containing magnesium (Mg) and calcium (Ca) with carbon dioxide (CO2) to fix it as carbonate (carbonate mineralization technology). Carbonates such as magnesium carbonate (MgCO3) and calcium carbonate (CaCO3) are very stable at room temperature and pressure and are not easily affected by environmental changes, so CO2 can be stably fixed in the minerals for a long period of time. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2025-62790 Summary of the Invention [Problem to be solved by the invention]

[0010] In the Advanced Mine Drainage Treatment Technology Development Project carried out from 2012 to 2014, the performance requirements for fill materials for abandoned tunnels at closed and abandoned mines included fluidity that allows them to be pumped, resistance to material separation due to volume changes after filling, strength after hardening to stabilize the filled space, shielding properties after hardening to reduce the amount of mine drainage, and non-elution of heavy metals and other harmful substances.In addition, in introducing the concept of CO2 fixation as added value to the business of closed and abandoned mines, a new required performance is the stability of the solid phase after CO2 fixation, that is, the carbonate minerals.

[0011] Wastewater from abandoned mines often has a sulfuric acidic pH of about 2-3 due to sulfide minerals. For example, the analysis of wastewater from mines in Hokkaido showed that the water quality was non-calcium carbonate, with SO4 2- When the filler material, which immobilizes CO2 as CaCO3, reacts with the sulfuric acid solution, the CaCO3 dissolves and forms secondary minerals such as CaSO4 (gypsum), causing the immobilized CO2 to leach out. Therefore, there is a possibility that the CO2 that was once immobilized may be released back into the environment.

[0012] Therefore, establishing a method for evaluating the long-term durability of carbon dioxide fixation fillers (low-carbon materials) that takes into account the risk of CO2 re-emission is thought to be an important indicator for calculating CO2 credits and economic effects. An object of the present invention is to provide a method for evaluating carbon dioxide fixing filler suitable as a technique for evaluating the long-term durability of carbon dioxide fixing filler to be placed in abandoned tunnels, etc., of suspended and abandoned mines, as well as an analysis method and analysis program that can be applied to said evaluation method. [Means for solving the problem]

[0013] In order to solve the above problems, a first aspect of the present invention provides a method for analyzing a carbon dioxide fixing filler having the following configurations (1) and (2).

[0014] (1) A method for analyzing a filler to be placed in an underground space, the filler being a carbon dioxide fixing filler containing carbonate produced by reacting a starting material with carbon dioxide.

[0015] (2) Physical quantities indicating the quality of groundwater present in the target underground space, the temperature and depth of the underground space, the amount of carbonate contained in the filler, the dissolution rate of the filler in the groundwater, the specific surface area of ​​the filler, and the ratio of the amount of groundwater inflowing into the filler and the amount of the filler are obtained, and the change over time in the amount of carbon dioxide fixed by the filler is analyzed based on the obtained physical quantities, the temperature and depth, the amount of carbonate, the dissolution rate, the specific surface area, and the ratio. A second aspect of the present invention provides a method for evaluating a carbon dioxide fixing filler having the above configurations (1) and (2) and the following configuration (3).

[0016] (3) A method for evaluating a filler to be placed in an underground space, in which the filler is evaluated based on the analysis results obtained in (2).

[0017] A third aspect of the present invention provides a method for analyzing a carbon dioxide fixing filler having the above configuration (1) and the following configuration (21). (21) Physical quantities indicating the quality of groundwater present in the target underground space, the temperature and depth of the underground space, the amount of carbonate contained in the filler, the dissolution rate of the filler in the groundwater, the specific surface area of ​​the filler, and the ratio of the amount of groundwater inflowing into the filler to the amount of the filler are obtained, and the obtained physical quantities, the temperature and depth, the amount of carbonate contained in the filler, the dissolution rate, the specific surface area, and the ratio are used as input information to perform an advection-dispersion analysis of the filler using a geochemical calculation code, thereby obtaining analysis results regarding the changes in the amount of carbon dioxide fixed by the filler over time.

[0018] A fourth aspect of the present invention provides a method for evaluating a carbon dioxide fixing filler having the above configurations (1) and (21) and the following configuration (31). (31) A method for evaluating a filler to be placed in an underground space, the filler being evaluated based on the analysis results obtained in (21).

[0019] A fifth aspect of the present invention provides an analysis program for a filler to be placed in an underground space, the filler being a carbon dioxide fixation filler containing carbonate produced by reacting a starting material with carbon dioxide, the analysis program causing a computer to execute the following steps: accept, as input information, physical quantities indicating the water quality of groundwater present in the target underground space, the temperature and depth of the underground space, the amount of carbonate contained in the filler, the dissolution rate of the filler in the groundwater, the specific surface area of ​​the filler, and the ratio of the amount of groundwater inflow into the filler and the amount of the filler; and obtain analysis results regarding the change over time in the amount of carbon dioxide fixation by the filler by performing an advection-dispersion analysis of the filler using a geochemical calculation code. [Effects of the Invention]

[0020] According to the present invention, there are provided a method for evaluating carbon dioxide fixing filler, which is suitable as a technique for evaluating the long-term durability of carbon dioxide fixing filler to be placed in abandoned tunnels of closed and abandoned mines, as well as an analysis method and analysis program that can be applied to said evaluation method. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a schematic diagram showing an abandoned mine having abandoned tunnels, which is an example of an underground space to which a method according to an embodiment of the present invention can be applied. FIG. [Figure 2] 1 is a flowchart illustrating a method according to one embodiment of the present invention. [Figure 3] 1 is a graph showing the change over time in the amount of carbon dioxide fixed in a carbon dioxide fixing filler obtained by a method according to one embodiment of the present invention. [Figure 4] FIG. 2 is a schematic diagram illustrating an example of a hardware configuration capable of implementing a method according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments. In the following embodiments, technically preferable limitations are imposed for carrying out the present invention, but these limitations are not essential requirements for the present invention.

[0023] As shown in Figure 1, in an abandoned mine 10, a filler (carbon dioxide fixing filler) 3 made of a carbon dioxide fixing material is placed in an abandoned mine tunnel (underground space) 2 formed in a mineralized zone 1. In a method according to one embodiment of the present invention, the carbon dioxide fixation life of the filler 3 placed in the abandoned mine tunnel 2 is evaluated.

[0024] In an abandoned mine 10, mine water 13 generated when rainwater 11 and groundwater 12 pass through a mineralized zone 1 is treated as mine wastewater and then released into the river. In addition, seepage water 15 generated when rainwater 11 and surface water 14 pass through a collection site 4 is also treated as mine wastewater and then released into the river. In one embodiment of the method, as shown in Figure 2, first, data on hydrogen ion concentration is obtained as a physical quantity indicating the water quality of groundwater present in an underground space (abandoned mine tunnel 2), and data on the temperature and depth of the underground space are also obtained (step S1).

[0025] The data may be obtained by field surveys or by examining existing data or literature values. Physical quantities that indicate groundwater quality include hydrogen ion concentration (pH), electrical conductivity (EC), oxidation-reduction potential (ORP), calcium (Ca) concentration, magnesium (Mg) concentration, sodium (Na) concentration, potassium (K) concentration, silica (Si) concentration, aluminum (Al) concentration, iron (Fe) concentration, and dissolved inorganic carbon (HCO3 - , CO3 2- ), sulfate ions (SO4 2- ) concentration, chloride ion (Cl - ) concentration, nitrate ion (NO3 - ) concentration, heavy metal ion concentration, etc.

[0026] The depth of the underground space can be calculated from the pressure in the underground space. Therefore, the pressure in the underground space can be measured in a field survey and the depth calculated using the measured value can be used, or the depth can be calculated using existing data on the pressure in the underground space. Information indicating the state of the underground space may include physical quantities indicating the quality of groundwater, the temperature and depth of the underground space, and, if necessary, the presence of animals that are subject to conservation.

[0027] Next, information on the starting material (substance before carbon dioxide fixation) of the filler made of the carbon dioxide fixation material is obtained (step S2). The reason for performing step S2 is that depending on the material (starting material) before carbon dioxide in the filler is fixed (reacted with carbon dioxide), a chemical reaction may occur in the filler during filling, producing carbonate, or the amount of carbonate may increase or decrease compared to the starting material. The starting material is, for example, a silicate mineral containing magnesium (Mg), calcium (Ca), etc. Note that step S2 is necessary if the starting material is a mineral other than a carbonate mineral, such as a silicate mineral, but is not necessary otherwise.

[0028] In addition, the main components of the starting materials are confirmed in order to trace the reaction process of the chemical reaction and to confirm the process by which carbonate was produced or whether the carbonate remains unchanged.

[0029] Next, the amount of substance (mol) of carbonate contained in the filler is obtained (step S3). Carbonates contained in the filler include CaCO3, MgCO3, CaMg(CO3)2, etc. Corresponding carbonate minerals include calcite (CaCO3), magnesite (MgCO3), dolomite (CaMg(CO3)2), etc. The amount of substance (mol) of carbonate contained in the filler may be obtained by actually analyzing the filler, or existing data may be used. Analytical methods include thin section observation, modal analysis, X-ray powder diffraction (XRD), X-ray fluorescence analysis (XRF), differential thermal analysis, wet analysis, analysis using a total organic carbon analyzer, and coulometer analysis.

[0030] Next, the dissolution rate of the filler in groundwater and the specific surface area of ​​the filler are obtained (step S4). Methods for obtaining the dissolution rate of the filler in groundwater include conducting tests using parameters that have a high contribution to carbonate stability from the data obtained in step S1 (hydrogen ion concentration in the groundwater, temperature and depth of the underground space), or using existing data. Here, in order to apply this to abandoned mines, the hydrogen ion concentration of groundwater is selected as the parameter that "highly contributes to the stability of carbonates." The specific surface area of ​​the filler can be obtained by measuring it using the BET method or by using existing data.

[0031] Next, the ratio of the amount of groundwater that comes into contact with the filler to the amount of the filler is obtained (step S5).

[0032] Next, using the information acquired in steps S1 to S5 as input information, an advection-diffusion analysis of the filler is performed using a geochemical calculation code (PHREEQC) to obtain analytical results regarding the secular change in the amount of carbon dioxide fixed in the filler (step S6). Here, the hydrogen ion concentration of the groundwater is used as a parameter to obtain a graph, for example, as shown in Figure 3. Next, the carbon dioxide fixation life of the filler is evaluated based on the obtained analysis results (step S7).

[0033] Figure 3 is a graph showing the change over time in the amount of carbon dioxide fixed by the filler, with different results being obtained when the hydrogen ion concentration of the groundwater is low (pH = 2 to 3) and when it is high (pH = 8 to 10).The graph in Figure 3 shows that when the hydrogen ion concentration of the groundwater is low, the rate at which the amount of carbon dioxide fixed by the filler decreases is faster than when it is high, and the number of years A at which it becomes nearly zero can be evaluated as the carbon dioxide fixation lifespan.

[0034] On the other hand, if the hydrogen ion concentration of the groundwater is high, the amount of carbon dioxide fixation in the filler may reach equilibrium at a certain point. In such a case, the number of years until the amount of carbon dioxide fixation reaches nearly zero may be evaluated as the carbon dioxide fixation lifespan. Alternatively, for example, the number of years B from the starting point at which the decrease in the amount of carbon dioxide fixation reaches equilibrium may be evaluated as the "number of years until the amount of carbon dioxide fixation reaches equilibrium."

[0035] In the method of this embodiment, PHREEQC is used as the geochemical calculation code, so the analysis code SOLUTION is used in step S1, and the analysis code EQUILIBRIUM PHASES is used in step S2. In step S4, the analysis code RATES obtains an empirical formula for the dissolution rate of the filler in groundwater, and the analysis code KINETICS performs a reaction rate analysis based on the empirical formula obtained by RATES to obtain the dissolution rate. In step S6, the analysis code TRANSPORT couples the reaction rate calculated by KINETICS to perform an advection-diffusion analysis.

[0036] In the method of this embodiment, the "carbon dioxide fixation lifespan of the filler" and "the number of years until the amount of carbon dioxide fixation reaches equilibrium" are evaluated based on the obtained analysis results. However, other examples of the evaluation content of the filler include "the number of years until the amount of carbon dioxide fixation of the filler reaches zero in 100 years" and "whether the filler can be used in the target underground space."

[0037] Furthermore, in the method of this embodiment, the geochemical calculation code PHREEQC published by the United States Geological Survey (USGS) is used to perform the advection-diffusion analysis of the filler, but the geochemical calculation code used in the method of the present invention is not limited to this, and other geochemical calculation codes (e.g., WATEQ4F, MINTEQA2, The Geochemist's Workbench, EQ3 / 6, MINEQL+, etc.) may also be used. Furthermore, advection-dispersion analysis, which is not an advection-diffusion analysis, may also be performed. Note that advection-diffusion analysis is included in advection-dispersion analysis.

[0038] The method of this embodiment can be implemented using, for example, the hardware configuration shown in Fig. 4. This hardware configuration includes an input device 21, a computer 22, and an output device 22. The input device 21 is, for example, a keyboard, and a person inputs the information acquired in steps S1 to S5 from the input device 21 to the computer 22. The computer 22 includes an advection-diffusion analysis unit 221. Based on the input information, the computer 22 performs an advection-diffusion analysis of the filler using the geochemical calculation code PHREEQC in the advection-diffusion analysis unit 221, obtains an analysis result regarding the secular change in the amount of carbon dioxide fixation in the filler (executes step S6), and outputs the analysis result to the output device 23. The output device 23 is, for example, a printer, and outputs the graph shown in FIG. 3 as an example.

[0039] Step S7 (evaluating the carbon dioxide fixation life of the filler based on the obtained analysis results) may be performed by a person or by a computer. As explained above, the evaluation method for a carbon dioxide fixing filler of this embodiment is a method of carrying out each step of the flowchart shown in Fig. 2, using the information acquired in steps S1 to S5 as input information and performing an advection-diffusion analysis of the filler using a geochemical calculation code to obtain analysis results regarding changes in the amount of carbon dioxide fixed in the filler over time, and evaluating the filler based on the obtained analysis results. The evaluation method for a carbon dioxide fixing filler of this embodiment is a suitable method for evaluating the long-term durability of carbon dioxide fixing filler to be placed in abandoned tunnels, etc., of suspended and abandoned mines.

[0040] [About the program] A program according to one embodiment of the present invention is an analysis program for carbon dioxide fixation filler that causes a computer to accept input information acquired in each of steps S1 to S5 in the flowchart of Figure 2 and to perform the operation of step S6 (performing an advection-diffusion analysis of the filler using PHREEQC as a geochemical calculation code to obtain analytical results regarding the change over time in the amount of carbon dioxide fixation in the filler).

[0041] This program is non-temporarily recorded on a recording medium such as a hard disk drive or memory, or on an optical disc such as a DVD disc or Blu-ray (registered trademark). This program may be distributed via the Internet. Furthermore, this program may be recorded on a cloud server and executed via the Internet.

[0042] [others] In the method of this embodiment, an advection-diffusion analysis of the filler is performed using a geochemical calculation code to obtain analysis results regarding the change over time in the amount of carbon dioxide fixed in the filler. Therefore, for example, the hardware configuration shown in Figure 4 is required. However, the present invention also includes a method of analyzing the change over time in the amount of carbon dioxide fixed in the filler based on the various values ​​(physical quantities, temperature and depth, amount of substance, dissolution rate, specific surface area, and ratio) obtained by manual calculation without using a geochemical calculation code. [Explanation of symbols]

[0043] 10 Abandoned mines 1 Mineralized Zone 2 Mine shaft (underground space) 3. Filler made of carbon dioxide fixing material (carbon dioxide fixing filler) 4 Collection point 11 Rainwater 12 Groundwater 13 Mine water 14 Surface water 15 Penetration water 21 Input Devices 22 Computer 23 Output Devices 221 Advection-Diffusion Analysis Section

Claims

1. A method for analyzing a filler material to be placed in an underground space, comprising: The filler is a carbon dioxide fixing filler containing a carbonate produced by reacting a starting material with carbon dioxide, Physical quantities that indicate the quality of groundwater present in the target underground space, the temperature and depth of said underground space; the amount of carbonate contained in the filler; the dissolution rate of the filler in the groundwater; the specific surface area of ​​the filler; and The ratio of the amount of groundwater inflow that contacts the filler to the amount of the filler is Get A method for analyzing a carbon dioxide fixing filler, which analyzes changes in the amount of carbon dioxide fixed by the filler over time based on the acquired physical quantities, the temperature and depth, the amount of substance, the dissolution rate, the specific surface area, and the ratio.

2. 2. The method for analyzing a carbon dioxide fixing filler according to claim 1, wherein the underground space is an abandoned tunnel of an abandoned mine, hydrogen ion concentration is used as the physical quantity indicating the water quality of the groundwater, and analysis is performed using the hydrogen ion concentration as a parameter.

3. A method for evaluating a filler material to be placed in an underground space, comprising: A method for evaluating a carbon dioxide fixing filler, wherein the filler is evaluated based on an analysis result obtained by the analysis method according to claim 1 or 2.

4. A method for analyzing a filler material to be placed in an underground space, comprising: The filler is a carbon dioxide fixing filler containing a carbonate produced by reacting a starting material with carbon dioxide, Physical quantities that indicate the quality of groundwater present in the target underground space, the temperature and depth of said underground space; the amount of carbonate contained in the filler; the dissolution rate of the filler in the groundwater; the specific surface area of ​​the filler; and The ratio of the amount of groundwater inflow that contacts the filler to the amount of the filler is Get A method for analyzing carbon dioxide fixing filler, which uses the acquired physical quantities, temperature and depth, amount of substance, dissolution rate, specific surface area, and ratio as input information and performs advection-dispersion analysis of the filler using a geochemical calculation code, thereby obtaining analytical results regarding the change in the amount of carbon dioxide fixed by the filler over time.

5. 5. The method for analyzing a carbon dioxide fixing filler according to claim 4, wherein the underground space is an abandoned tunnel of an abandoned mine, hydrogen ion concentration is used as the physical quantity indicating the water quality of the groundwater, and the analysis results are obtained using the hydrogen ion concentration as a parameter.

6. A method for evaluating a filler material to be placed in an underground space, comprising: A method for evaluating a carbon dioxide fixing filler, wherein the filler is evaluated based on the analysis results obtained by the analysis method according to claim 4 or 5.

7. An analysis program for filling materials to be placed in underground spaces, The filler is a carbon dioxide fixing filler containing a carbonate produced by reacting a starting material with carbon dioxide, Accepting as input information physical quantities indicating the quality of groundwater present in the target underground space, the temperature and depth of the underground space, the amount of carbonate contained in the filler, the dissolution rate of the filler in the groundwater, the specific surface area of ​​the filler, and the ratio of the amount of groundwater inflow contacting the filler to the amount of the filler; Performing an advection-dispersion analysis of the filler using a geochemical calculation code to obtain an analysis result regarding the change over time in the amount of carbon dioxide fixed by the filler; An analysis program for carbon dioxide fixation filler to be executed on a computer.

8. 8. The analysis program for carbon dioxide fixation filler according to claim 7, wherein the underground space is an abandoned tunnel of an abandoned mine, hydrogen ion concentration is used as the physical quantity indicating the water quality of the groundwater, and the analysis results are obtained using the hydrogen ion concentration as a parameter.

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