Integrated Method for Direct CO₂ Capture-Geological Utilization-Mineralization Sequestration in Mines

Abstract

The present invention belongs to the technical field of carbon dioxide emission reduction in coal mines, and relates to an integrated method for direct capture - geological utilization - mineralization and sequestration of mine CO2, which includes the following steps: First, arrange CO2 gas concentration and air quality monitors in the return airway, collect environmental data and transmit it to the interactive computer for analysis, and send a signal by the adaptive early warning device according to the set threshold. At the end of the return airway, inhale, react, purify, and pressurize CO2 to prepare liquid CO2 in real time; Supercritical CO2 is used to prevent coal and gas outburst disasters, and liquid CO2 is used to prevent goaf fires to achieve geological utilization; Finally, through intelligent identification and grasping, gangue and CO2 are used to generate carbonate minerals, which are uniformly mixed with other materials to obtain paste filling materials, and are transported to the goaf through the grouting high-pressure pipeline for mineralization and sequestration; The present invention is an integrated method for direct capture, geological utilization, and mineralization and sequestration of CO2, which effectively reduces the carbon emissions during coal mine production.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon dioxide emission reduction in coal mines, and relates to an integrated method for direct capture - geological utilization - mineralization and storage of CO2 in mines. Background Technique

[0002] In underground coal mining, a large amount of CO2 is generated. The main sources include the slow oxidation of coal and carbonaceous strata, the outburst of coal seam carbon dioxide, the decay and deterioration of pit props, blasting operations, the breathing of underground workers, etc. If the CO2 generated in coal mines is directly discharged into the atmosphere without capture, it will inevitably increase the greenhouse gas emissions and have an adverse impact on carbon emission reduction in the coal industry.

[0003] CCUS (Capture, Utilization, and Storage of CO2) is an important way to achieve carbon dioxide emission reduction in coal mining. CO2 has unique physical and chemical properties. The carbon dioxide captured underground can be locally converted into utilizable resources. For example, liquid CO2 has the functions of cooling and inerting, and can be used for the prevention and control of coal mine fires; supercritical CO2 can cause phase change to fracture coal bodies, and the generated gaseous CO2 can effectively displace gas desorption, realizing coal seam permeability enhancement and improving gas extraction efficiency. At the same time, CO2 can react with gangue under certain conditions to form stable carbonate minerals for mineralization and storage. However, there is currently a lack of a method for directly capturing, geologically utilizing, and mineralizing and storing CO2 in coal mines. Summary of the Invention

[0004] In view of the above problems, the present invention provides a method for direct capture - geological utilization - mineralization and storage of CO2 in mines. The method aims to directly collect the CO2 generated in coal mining and return air headings, further convert it into resources useful for the coal mining face, and effectively store the unutilized CO2 in the goaf, which helps to reduce the CO2 concentration in the working area and improve the working environment of miners.

[0005] To achieve the above object, the technical solution provided by the present invention is as follows:

[0006] Step 1, establish a CO2 concentration prediction model, and monitor the CO2 concentration in the mine return air heading through the CO2 concentration prediction model.

[0007] Step 2, when the CO2 concentration in the return air heading of the well is monitored to be abnormal, collect and purify the CO2 to obtain gaseous CO2, and then compress part of the gaseous CO2 to obtain liquid CO2.

[0008] Step 3, utilize liquid CO2. When preventing and controlling low - permeability high - gas coal seams, pressurize the liquid CO2 to become supercritical CO2, and then use the supercritical CO2 as a fracturing medium. When the internal temperature of the goaf rises abnormally or there is smoke, use the stored liquid CO2 as a cooling medium.

[0009] Step 4: Add water to the remaining purified gaseous CO2 and mix it with gangue to obtain carbonate minerals, and then process the carbonate minerals into a fluid paste filling material to fill the goaf.

[0010] The features of the present invention also lie in:

[0011] Furthermore, when establishing the CO2 concentration prediction model, first, at the entrance, middle, and exit of the return airway, 4G / Wifi wireless CO2 gas concentration sensors and air quality monitors are arranged as three monitoring points to work together continuously to monitor the CO2 concentration in the mine return airway in the environment and environmental parameters including temperature, humidity, air pressure, PM2.5 particulate matter concentration, and oxygen concentration. Clean, denoise, and calibrate the monitored CO2 concentration values and environmental parameters, and establish a CO2 concentration prediction model through a deep learning algorithm based on the cleaned, denoised, and calibrated CO2 concentration values and environmental parameters.

[0012] Furthermore, when the CO2 concentration in the mine return airway is monitored to be abnormal, different CO2 warning signals are issued. When the CO2 concentration in the mine return airway exceeds 0.75%, a flash alarm is issued. When the CO2 concentration in the district return airway exceeds 1.00%, a sound alarm message is issued. When the CO2 concentration in the district return airway exceeds 1.25%, both a flash and a sound alarm message are sent simultaneously.

[0013] Furthermore, the distance between the 4G / Wifi wireless CO2 gas concentration sensor and the air quality monitor is less than 50 cm.

[0014] Furthermore, when adding water to the remaining purified gaseous CO2 and mixing it with gangue, when collecting gangue, images of coal and gangue on the coal conveyor belt are collected. Denoise, enhance the contrast, perform gray-scale analysis, texture feature extraction, and edge detection techniques on the images of coal and gangue to obtain the feature information of coal and gangue. Use the extracted feature information to train a machine learning model to obtain an identification model, and automatically identify the gangue through the identification model. When the gangue on the coal conveyor belt is identified, the gangue is automatically grabbed and collected.

[0015] Furthermore, when adding purified gaseous CO2 to water and mixing it with gangue, the temperature is controlled at 25°C to 70°C, the pH value is 7.3, the volume fraction of CO2 is controlled at 30%, and the time is 1 h to 4 h.

[0016] Furthermore, when processing the carbonate minerals into a fluid paste filling material, cement, binder, fly ash, thickener, water reducer, and carbonate minerals are mixed.

[0017] An integrated method for direct capture - geological utilization - mineralization and storage of CO2 in mines of the present invention proposes a method for direct capture - geological utilization - mineralization and storage of CO2 in mines. By integrating advanced sensors and an automatic control system, real - time monitoring and automatic adjustment of CO2 concentration, pressure and key underground parameters are achieved. Using efficient storage materials and technologies, it ensures that the captured CO2 can be stored stably for a long time. Through this method, the safety of underground operations is improved, and coal mining enterprises can significantly reduce greenhouse gas emissions during operations. Brief Description of the Drawings

[0018] Figure 1 It is a schematic diagram of the overall structure of the method of the present invention.

[0019] Figure 2 It is a schematic diagram of the structure of the CO2 intelligent monitoring and sensing method in the present invention.

[0020] Figure 3 It is a schematic diagram of the structure of the CO2 direct capture and treatment method in the present invention.

[0021] Figure 4 It is a schematic diagram of the structure of the method for preventing gas with supercritical CO2 and extinguishing fire with liquid - phase CO2 in the present invention.

[0022] Figure 5 It is a schematic diagram of the structure of the coal - based solid waste carbon sequestration method in the present invention.

[0023] Figure 6 It is a schematic diagram of the structure of the gob filling and storage method in the present invention.

[0024] Reference numerals: 1, CO2 intelligent monitoring and sensing module; 1-1, 4G / Wifi wireless CO2 gas concentration sensor; 1-2, air quality monitor; 1-3, interactive computer; 1-4, adaptive early warning device; 1-5, working control box; 2, CO2 direct capture and treatment module; 2-1, dirty air collection device; 2-2, CO2 absorption device; 2-3, CO2 desorption device; 2-4, ammonia water circulation device; 2-5, heat exchanger; 2-6, CO2 purification device; 2-7, vacuum booster pump; 2-8, liquid CO2 storage tank; 2-9, valve I; 2-10, valve II; 2-11, liquid outlet valve; 2-12, inlet valve; 2-13, gas two-way valve; 2-14, valve III; 2-15, valve IV; 3, supercritical CO2 gas control for gas module; 3-2, supercritical CO2 special pump; 3-3, valve V; 3-4, safety monitoring device; 3-5, fracturing pipe; 3-6, gas drainage pipe; 3-7, intelligent gas drainage pumping station; 3-8, gas flow sensor; 3-9, gas transmission pipe; 4, liquid phase CO2 fire prevention and extinguishing module; 4-1, cryogenic gate valve; 4-2, cryogenic infusion safety valve; 4-3, cryogenic injection safety valve; 4-4, infusion pipeline; 4-5, fire prevention and extinguishing injection device; 4-6, leakage alarm device; 4-7, CO2 concentration sensor; 4-8, infusion parameter optimization computer; 5, coal-based solid waste carbon sequestration module; 5-1, underground transfer machine; 5-2, long-distance scraper conveyor; 5-3, separation and queuing mechanism; 5-4, X-ray exciter; 5-5, high-speed identification camera; 5-6, X-ray receiver; 5-7, gangue intelligent control system; 5-8, automatic sorting device; 5-9, gangue storage device; 5-10, reaction device; 5-11, agitator; 5-12, wet controller; 5-13, gas control valve; 6, goaf filling and sealing module; 6-1, mixer; 6-2, additive dosing device; 6-3, liquid supply pipeline; 6-4, grouting valve; 6-5, safety valve; 6-6, control and pumping device; 6-7, grouting high-pressure pipeline; 6-8, solid transmission pipeline. Detailed implementation mode

[0025] The technical solutions in the present invention will be clearly and elaborately described below in conjunction with the accompanying drawings. Among them, in the description of the embodiments of the present invention, unless otherwise specified, " / " means "or". For example, A / B may represent A or B. The "and / or" in the text is only a description of the association relationship between associated objects, indicating that there can be three relationships. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, in the description of the embodiments of the present invention, "a plurality of" means two or more than two. The following terms "first" and "second" are only for descriptive purposes and cannot be construed as implying or suggesting relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features.

[0026] As Figure 1 , Figure 2 , Figure 3 , Figure 4 shown, the present invention provides an integrated method for direct capture - geological utilization - mineralization and storage of CO2 in mines, including the following steps:

[0027] Step 1, establish a CO2 concentration prediction model, and monitor the CO2 concentration in the mine return airway through the CO2 concentration prediction model.

[0028] Step 2, when the CO2 concentration in the well return airway is monitored to be abnormal, collect and purify the CO2 to obtain gaseous CO2, and then compress part of the gaseous CO2 to obtain liquid CO 2， and store the liquid CO2.

[0029] Step 3, when using liquid CO2 to prevent and control low-permeability high-gas coal seams, pressurize the liquid CO2 to become supercritical CO2, and then use the supercritical CO2 as a fracturing medium, that is, transport the supercritical CO2 into the fracturing pipe 3-5 used for coal seam gas extraction as a fracturing medium. When the temperature inside the goaf rises abnormally or there is smoke, use the stored liquid CO2 as a cooling medium, that is, inject the stored liquid CO2 into the goaf to reduce the temperature inside the goaf.

[0030] Step 4, add water to the remaining purified gaseous CO2 and mix it with gangue to obtain carbonate minerals, and then process the carbonate minerals into a fluid paste filling material to fill the goaf, completing the mineralization and storage of CO2.

[0031] As Figure 1 , Figure 2As shown in the figure, when establishing the CO2 concentration prediction model, first, a CO2 intelligent monitoring and perception module 1 is arranged in the return airway. The CO2 intelligent monitoring and perception module includes three 4G / Wifi wireless CO2 gas concentration sensors 1-1, three air quality monitors 1-2, an interactive computer 1-3, an adaptive early warning device 1-4, and a working control box 1-5. The three 4G / Wifi wireless CO2 gas concentration sensors 1-1 are respectively arranged at the entrance, middle, and exit of the return airway as three monitoring points. The three air quality monitors 1-2 are also respectively arranged at the entrance, middle, and exit of the return airway. The three 4G / Wifi wireless CO2 gas concentration sensors 1-1 and the three air quality monitors 1-2 work together to continuously monitor the CO2 concentration and environmental parameters in the mine return airway of the environment, including temperature, humidity, air pressure, PM2.5 particle concentration, and oxygen concentration. The monitored CO2 concentration values and environmental parameters are transmitted to the interactive computer 1-3. The interactive computer 1-3 is used to clean, denoise, and calibrate the CO2 concentration values and environmental parameters. According to the cleaned, denoised, and calibrated CO2 concentration values and environmental parameters, a CO2 concentration prediction model is established through a deep learning algorithm.

[0032] Furthermore, based on the CO2 prediction data and the corresponding environmental parameters obtained through the CO2 concentration prediction model, decision-making schemes under different CO2 concentration situations and different environmental parameters are formulated. A threshold alarm mechanism for CO2 concentration is set. The adaptive early warning device 1-4 issues a warning signal through the interactive computer 1-3 and takes corresponding alarm measures (flashing lights, sound alarms) according to the warning level. The working control box 1-5 realizes the power supply for the 4G / Wifi wireless CO2 gas concentration sensors 1-1, air quality monitors 1-2, interactive computer 1-3, and adaptive early warning device 1-4.

[0033] As Figure 3As shown in the figure, the CO2 direct capture and treatment module 2 used for capturing and purifying gaseous CO2 includes: a dirty air collection device 2-1, a CO2 absorption device 2-2, a CO2 desorption device 2-3, an ammonia water circulation device 2-4, a heating exchanger 2-5, a CO2 purification device 2-6, a vacuum booster pump 2-7, a liquid CO2 storage tank 2-8, a valve I 2-9, a valve II 2-10, a liquid outlet valve 2-11, an intake valve 2-12, a gas two-way valve 2-13, a valve III 2-14, and a valve IV 2-15. When a CO2 warning signal is received, the dirty air collection device 2-1 is started, and the gas containing CO2 is sucked into the air intake through the built-in fan and pipeline. The collected dirty air is sent into the filter to remove particulate matter, and the valve I 2-9 is opened to transport it to the CO2 absorption device 2-2, where the gas containing CO2 contacts and reacts with the ammonia water solution. CO2 is absorbed into the ammonia water, and ammonium carbonate is formed by the reaction. The ammonium carbonate formed after the CO2 is absorbed and saturated is transported to the CO2 desorption device 2-3 through the valve II 2-10, and then the heating exchanger 2-5 desorbs from the ammonia water by the method of heating up, and the released CO2 is transported to the CO2 purification device through the gas two-way valve 2-13. At the same time, the released ammonia gas is recycled to the ammonia water circulation device 2-4 through the intake valve 2-12, and the ammonia water solution is re-proportioned. The ammonia water solution is supplemented into the CO2 absorption device 2-2 through the pipeline by the liquid outlet valve 2-11. The valve III 2-14 is opened, and the internal pressure of the CO2 purification device 2-6 is adjusted by the vacuum booster pump 2-7 to compress the CO2 gas to a high-pressure state. The valve IV 2-15 is connected to the liquid CO2 storage tank 2-8, and the liquid CO2 is stored in the liquid CO2 storage tank 2-8. Among them, the chemical reaction formulas involved are as follows:

[0034] CO2(g)+2NH4OH(aq)→(NH 4)2 CO3(aq)+H2O(l).

[0035] (NH4)2CO3(s)→2NH3(g)+CO2(g)+H2O(l).

[0036] As Figure 4As shown in the figure, when preventing and controlling low-permeability high-gas coal seams, the supercritical CO2 gas prevention and control module 3 used includes: a supercritical CO2 special pump 3-2, a valve Ⅴ3-3, a safety monitoring device 3-4, a fracturing pipe 3-5, a gas drainage pipe 3-6, an intelligent gas drainage pumping station 3-7, a gas flow sensor 3-8, and a gas delivery pipe 3-9. First, conduct inspections and commissioning before starting the equipment to ensure the normal operation of the liquid CO2 storage tank 2-8, the supercritical CO2 special pump 3-2, and the safety monitoring device 3-4. Slowly open the valve Ⅴ3-3 of the liquid CO2 storage tank 2-8 to start delivering liquid CO2 to the supercritical CO2 special pump 3-2, and control the suction pressure of the pump to ensure it is within the normal working range. Start the supercritical CO2 special pump 3-2 and gradually increase the pressure until the CO2 reaches the supercritical state. Activate the safety monitoring device 3-4 to monitor the pressure, temperature, flow rate, and liquid level in real time, and set the alarm threshold of the monitoring system to ensure timely response in case of abnormalities. Open the cut-off device on the safety monitoring device 3-4 to allow the supercritical CO2 to enter the pipeline and ensure uniform pipeline pressure. Confirm the position and fixation of the fracturing pipe 3-5, check the gaskets, rupture discs, and heating pipes, remotely start the heating of the fracturing pipe 3-5 in a safe area, and tighten the alloy cap of the fracturing pipe to ensure the fracturing pipe is firmly fixed in the borehole and start the blasting procedure. After the blasting is completed, start the intelligent gas drainage pumping station 3-7 to start draining gas, open the gas flow sensor 3-8 on the gas drainage pipe 3-6 to monitor the gas drainage volume, and connect the drained gas to the underground pipeline system through the gas delivery pipe 3-9 to effectively drain the gas in the underground to the ground.

[0037] As Figure 4As shown in the figure, when it is found that the temperature inside the goaf rises abnormally or there is smoke, the liquid-phase CO2 fire prevention and extinguishing module 4 used includes: a low-temperature gate valve 4-1, a low-temperature infusion safety valve 4-2, a low-temperature injection safety valve 4-3, an infusion pipeline 4-4, a fire prevention and extinguishing injection device 4-5, a leakage alarm device 4-6, a CO2 concentration sensor 4-7, and an infusion parameter optimization computer 4-8. First, open the low-temperature gate valve 4-1 connecting the liquid CO2 storage tank 2-8 and the goaf to prepare for transporting liquid CO2. Start the infusion parameter optimization computer 4-8 to issue an instruction to open the low-temperature injection safety valve 4-3, and transport the liquid CO2 from the liquid CO2 storage tank 2-8 to the fire prevention and extinguishing injection device 4-5 to quickly release the liquid CO2, reduce the temperature in the goaf, and extinguish the fire source. Open the low-temperature infusion safety valve 4-2 to inject the liquid CO2 through the infusion pipeline 4-4 to reduce the temperature in the goaf. According to the environmental changes, dynamically adjust the opening and closing degrees of the low-temperature infusion safety valve 4-2 and the low-temperature injection safety valve 4-3 to ensure the fire extinguishing effect and operation safety. The leakage alarm device 4-6 and the CO2 concentration sensor 4-7 are installed around the CO2 transmission pipeline to monitor the leakage of liquid CO2 in real time. Once the leakage detector detects CO2 leakage, immediately trigger the alarm system, close all valves and stop the transportation to ensure the safety of personnel and equipment.

[0038] Furthermore, when adding water to the remaining purified gaseous CO2 and mixing it with gangue, when collecting gangue, first collect images of coal and gangue on the coal conveyor belt. Denoise, enhance the contrast, perform gray-scale analysis, texture feature extraction, and edge detection techniques on the images of coal and gangue to obtain the characteristic information of coal and gangue. Use the extracted characteristic information to train a machine learning model to obtain an identification model. Automatically identify the gangue through the identification model, automatically grab the gangue when the gangue on the coal conveyor belt is identified, and collect the gangue.

[0039] As Figure 5As shown in the figure, when mineralizing and sequestering the remaining purified gaseous CO2, the coal-based solid waste carbon sequestration module 5 used includes: a downhole transfer machine 5-1, a long-distance scraper conveyor 5-2, a separation and queuing mechanism 5-3, an X-ray exciter 5-4, a high-speed identification camera 5-5, an X-ray receiver 5-6, a gangue intelligent control system 5-7, an automatic sorting device 5-8, a gangue storage device 5-9, a reaction device 5-10, a stirrer 5-11, a wet process controller 5-12, and a gas control valve 5-13. First, the coal mined by the coal shearer and initially crushed is transferred by the downhole transfer machine 5-1 to the long-distance scraper conveyor 5-2. The separation and queuing mechanism 5-3 installed on the long-distance scraper conveyor sorts coal and gangue of different sizes or types. When the coal passes by, the X-ray exciter 5-4, the X-ray receiver 5-6, and the high-speed identification camera 5-5 collect images of the coal and gangue on the conveyor belt in real time. The collected data is transmitted to the gangue intelligent control system 5-7 for denoising and contrast enhancement to improve the image quality. Through gray-scale analysis, texture feature extraction, and edge detection techniques, the characteristic information of coal and gangue is extracted from the image to distinguish coal and gangue. Using the extracted characteristic information, a machine learning model is trained to achieve automatic identification of gangue. The gangue intelligent control system 5-7 sends the position information and identification result of the gangue to the automatic sorting device 5-8. According to the position and movement state of the gangue, the optimal grasping path is planned, and after grasping, it is collected into the gangue storage device 5-9. The gangue in the gangue storage device is transported to the reaction device 5-10, and CO2 is introduced through the gas control valve 5-13 and water is added through the CO2 purification device 2-6, and they are mixed by the stirrer 5-11. CO2 reacts with calcium and magnesium ions in the solid waste to form carbonate minerals. The wet process controller 5-12 is used to monitor the temperature, pH value, and CO2 volume fraction in the whole carbonation reaction process in real time to achieve automatic control of the reaction conditions.

[0040] As Figure 6As shown in the figure, carbonate minerals are processed into a fluid paste filling material, and finally the paste filling material is transported to the goaf to complete the mineralization and storage of purified gaseous CO2. The goaf filling and storage module 6 used includes: a mixer 6-1, an additive dosing device 6-2, a liquid supply pipeline 6-3, a grouting valve 6-4, a safety valve 6-5, a control and pumping device 6-6, a grouting high-pressure pipeline 6-7 and a solid transmission pipeline 6-8. First, through the solid transmission pipeline 6-8, the carbonate minerals are transported to the mixer 6-1 and started; through the liquid supply pipeline 6-3, the remaining liquid after the reaction is transported to the mixer 6-1, and the additive dosing device 6-2 is opened to add the required cement, binder, fly ash, thickener, and water reducer into the mixer 6-1 to ensure that the carbonate, cement, binder, fly ash, thickener, and water reducer are fully mixed in the mixer 6-1 to form a homogeneous and fluid paste filling material. Before starting the filling, check whether the grouting valve 6-4 and the safety valve 6-5 are in the correct positions, open the grouting valve 6-4, start the control and pumping device 6-6, and transport the paste filling material to the goaf through the grouting high-pressure pipeline 6-7. Monitor the pressure and flow rate during the pumping process through the grouting control and pumping device 6-6 to ensure the smooth progress of the filling operation. Through the sensing system of the installed safety valve 6-5, monitor the transportation and filling conditions of the filling material in real time, and adjust the pumping pressure, flow rate, or stirring speed according to the monitoring results to optimize the filling effect. When the filling reaches the predetermined amount or is completed, close the grouting valve 6-4, and then stop the control and pumping device 6-6 and the mixer 6-1, and clean them to remove the residual filling material.

[0041] Further, as Figure 2 shown in the figure, the 4G / Wifi wireless CO2 gas concentration sensor 1-1 should be vertically suspended at a position with stable air flow and uniform gas mixing to ensure accurate measurement, and should be installed at a position that is convenient for maintenance and does not affect the pedestrians and vehicles in the return airway. When the CO2 concentration in the mine return airway is monitored to be abnormal, different CO2 warning signals are issued. When the CO2 concentration in the mine return airway exceeds 0.75%, a flash alarm is issued; when the CO2 concentration in the return airway of the mining area exceeds 1.00%, a sound alarm message is issued; when the CO2 concentration in the return airway of the mining area exceeds 1.25%, a flash and sound alarm message is sent simultaneously. The air quality monitor 1-2 and the 4G / Wifi wireless CO2 gas concentration sensor 1-1 are installed at the same position with an interval of no more than 50 cm.

[0042] Further, as Figure 3As shown, in the CO2 absorption device 2-2, the mass fraction of the ammonia water solution for capturing CO2 is 15%, the pH of the solution is 13, the temperature is controlled at 45°C. The ammonia water solution that has absorbed CO2 needs to be heated to desorb CO2 and release pure CO2 gas. Heat is transferred to the ammonia water solution through high-temperature water to increase its temperature and promote the desorption of CO2.

[0043] Furthermore, as Figure 4 shown, the infusion pipeline 4-4 can withstand the high pressure and low temperature conditions during the transportation of liquid CO2 to prevent corrosion and maintain structural integrity. The infusion parameter optimization computer 4-8 can ensure that in the event of a fire or other safety threats, it can promptly switch to spraying or transportation to effectively release liquid CO2 to extinguish the fire or control safety risks to the greatest extent.

[0044] Furthermore, as Figure 5 shown, the stirring speed of the stirrer 5-11 is set at 500 r / min, the wet method controller 5-12 controls the temperature at 25°C to 70°C, the optimal pH value is 7.3, the CO2 volume fraction is controlled at 30%, and the reaction time is 1 h - 4 h.

[0045] Furthermore, as Figure 6 shown, the control and pumping device 6-6 is used to monitor the preparation of the paste filling material and adjust the key parameters during the filling process, such as temperature, pressure, flow rate, and material uniformity, to ensure the safety and effectiveness of the filling operation.

[0046] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. An integrated method for direct CO2 capture - geological utilization - mineralization and storage in coal mines, characterized in that It includes the following steps: Step 1: Establish a CO2 concentration prediction model and monitor the CO2 concentration in the mine return airway through the CO2 concentration prediction model; Step 2: When the CO2 concentration in the mine return airway is monitored to be abnormal, collect and purify the CO2 to obtain gaseous CO2, and then compress part of the gaseous CO2 to obtain liquid CO2; Step 3: Utilize the liquid CO2. When preventing and controlling low-permeability high-gas coal seams, pressurize the liquid CO2 to become supercritical CO2, and then use the supercritical CO2 as a fracturing medium. When the temperature inside the goaf rises abnormally or there is smoke, use the stored liquid CO2 as a cooling medium; Step 4: Add water to the remaining purified gaseous CO2 and mix it with gangue to obtain carbonate minerals, and then process the carbonate minerals into a flowable paste filling material to fill the goaf; When establishing the CO2 concentration prediction model, first arrange 4G / Wifi wireless CO2 gas concentration sensors (1-1) and air quality monitors (1-2) as three monitoring points at the entrance, middle, and exit of the return airway to work together to continuously monitor the CO2 concentration in the mine return airway of the environment and environmental parameters including temperature, humidity, air pressure, PM2.5 particulate matter concentration, and oxygen concentration. Clean, denoise, and calibrate the monitored CO2 concentration values and environmental parameters, and establish a CO2 concentration prediction model through a deep learning algorithm based on the cleaned, denoised, and calibrated CO2 concentration values and environmental parameters; When the CO2 concentration in the mine return airway is monitored to be abnormal, different CO2 warning signals are issued. When the CO2 concentration in the mine return airway exceeds 0.75%, a flash alarm is issued. When the CO2 concentration in the district return airway exceeds 1.00%, a sound alarm message is issued. When the CO2 concentration in the district return airway exceeds 1.25%, both flash and sound alarm messages are sent simultaneously; When adding water to the remaining purified gaseous CO2 and mixing it with gangue, first collect the gangue, collect images of coal and gangue on the coal conveyor belt, denoise, enhance the contrast, perform gray-scale analysis, texture feature extraction, and edge detection techniques on the images of coal and gangue to obtain the characteristic information of coal and gangue. Utilize the extracted characteristic information to train a machine learning model to obtain an identification model, automatically identify the gangue through the identification model, automatically grab the gangue when the gangue on the coal conveyor belt is identified, and collect the gangue; 2. The integrated method for direct CO2 capture - geological utilization - mineralization and storage in coal mines according to claim 1, wherein The distance between the 4G / Wifi wireless CO2 gas concentration sensor (1-1) and the air quality monitor (1-2) is less than 50 cm.

3. The integrated method for direct CO2 capture - geological utilization - mineralization and storage in coal mines according to claim 1, wherein, When adding the purified gaseous CO2 to water and mixing it with gangue, the temperature is controlled at 25°C to 70°C, the pH value is 7.3, the volume fraction of CO2 is controlled at 30%, and the time is 1 h to 4 h.

4. The integrated method for direct capture - geological utilization - mineralization and storage of CO2 in mines according to claim 1, characterized in that, When processing the carbonate minerals into a flowable paste filling material, mix cement, binder, fly ash, thickener, water reducer, and carbonate minerals.

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