Mine CO2 direct capture-geological utilization-mineralization storage integrated method

Abstract

The invention belongs to the technical field of coal mine underground carbon dioxide emission reduction, and relates to a mine CO2 direct capture-geological utilization-mineralization storage integrated method which comprises the following steps: firstly, arranging a CO2 gas concentration and air quality monitor in a return airway, collecting environmental data and transmitting the environmental data to an interactive computer for analysis; according to a set threshold value, a self-adaptive early warning device sends out a signal, CO2 is sucked in at the end of a return airway, and liquid CO2 is prepared in real time through reaction, purification and pressurization; the supercritical CO2 is used for preventing and treating coal and gas outburst disasters, and the liquid CO2 is used for preventing and treating goaf fire disasters to realize geological utilization; finally, gangue is intelligently recognized and grabbed to generate carbonate minerals with CO2, the carbonate minerals are evenly mixed with other materials, a paste filling material is obtained, and the paste filling material is conveyed to a goaf through a grouting high-pressure pipeline to be mineralized and sealed. The invention relates to a CO2 direct capture, geological utilization and mineralization storage integrated method, which effectively reduces the carbon emission in the coal mine production process.

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 of direct capture-geological utilization-mineralization storage of CO2 in mines. Background Art

[0002] In underground coal mining, a large amount of CO2 is generated, mainly from the slow oxidation of coal and carbonaceous rock layers, carbon dioxide outflow from coal seams, decay and deterioration of pit wood, blasting operations, and breathing of underground workers. If the CO2 generated underground in coal mines is directly discharged into the atmosphere without being captured, it will inevitably increase 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 converted into usable resources on site. For example, liquid CO2 has cooling, inertization and suffocation effects, which can be used to prevent and control coal mine fires; supercritical CO2 can phase change and crack the coal body, and the gaseous CO2 produced can effectively displace gas desorption, increase the permeability of coal seams, and improve gas extraction efficiency. At the same time, CO2 can react with gangue under certain conditions to generate stable carbonate minerals for mineralization and storage. However, there is currently a lack of methods for direct capture, geological utilization and mineralization storage of CO2 underground in coal mines. Summary of the invention

[0004] In response to the above problems, the present invention provides a method for direct capture-geological utilization-mineralization storage of CO2 in mines. The method aims to directly collect the CO2 generated in coal mining and return air lanes, further convert it into resources useful for the coal mining working face, and effectively seal 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 purpose, the technical solution provided by the present invention is as follows: Step 1: Establish a CO2 concentration prediction model and monitor the CO2 concentration in the mine return air lane through the CO2 concentration prediction model.

[0006] Step 2: When an abnormal CO2 concentration is detected in the return air lane of the well, the CO2 is collected and purified to obtain gaseous CO2, and then part of the gaseous CO2 is compressed to obtain liquid CO2.

[0007] Step 3, using liquid CO2, when preventing and controlling low-permeability high-gas coal seams, pressurize the liquid CO2 into supercritical CO2, and then use the supercritical CO2 as a fracturing medium. When the temperature inside the goaf rises abnormally or smoke appears, the stored liquid CO2 is used as a cooling medium.

[0008] 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.

[0009] The features of the present invention also include: 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.

[0010] 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.

[0011] Furthermore, the distance between the 4G / Wifi wireless CO2 gas concentration sensor and the air quality monitor is less than 50 cm.

[0012] 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. Using the extracted feature information, train a machine learning model to obtain an identification model, automatically identify the gangue through the identification model, and automatically grab the gangue when the gangue on the coal conveyor belt is identified, and collect the gangue.

[0013] 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.

[0014] Furthermore, when processing the carbonate minerals into a flowable paste filling material, cement, binder, fly ash, thickener, water reducer, and carbonate minerals are mixed.

[0015] 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

[0016] Figure 1 It is a schematic diagram of the overall structure of the method of the present invention.

[0017] Figure 2 It is a schematic diagram of the structure of the CO2 intelligent monitoring and sensing method in the present invention.

[0018] Figure 3 It is a schematic diagram of the structure of the CO2 direct capture and treatment method in the present invention.

[0019] Figure 4 It is a schematic diagram of the structure of the method for preventing gas with supercritical CO2 and preventing fire with liquid - phase CO2 in the present invention.

[0020] Figure 5 It is a schematic diagram of the structure of the coal - based solid waste carbon sequestration method in the present invention.

[0021] Figure 6 It is a schematic diagram of the structure of the gob filling and storage method in the present invention.

[0022] 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, heating 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, intake 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 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 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 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

[0023] 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 mean A or B. The "and / or" in the text is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can mean: 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 used 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.

[0024] 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: Step 1, establish a CO2 concentration prediction model, and monitor the CO2 concentration in the mine return airway through the CO2 concentration prediction model.

[0025] 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 CO 2， and store the liquid CO2.

[0026] 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.

[0027] 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 - like filling material to fill the goaf, completing the mineralization and storage of CO2.

[0028] As Figure 1 , Figure 2As shown in the figure, when establishing the CO2 concentration prediction model, first, the CO2 intelligent monitoring and sensing module 1 is arranged in the return air roadway. The CO2 intelligent monitoring and sensing 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 air roadway as three monitoring points. The three air quality monitors 1-2 are also respectively arranged at the entrance, middle, and exit of the return air roadway. 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 air roadway in the environment, including temperature, humidity, air pressure, PM2.5 particulate matter 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.

[0029] Furthermore, based on the CO2 prediction data and the corresponding environmental parameters obtained through the CO2 concentration prediction model, decision-making schemes for 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.

[0030] As Figure 3As shown in the figure, the direct CO2 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 air inlet valve 2-12, a gas two-way valve 2-13, a valve III 2-14 and a valve IV 2-15. When a CO2 early warning signal is received, the dirty air collection device 2-1 is started, and the gas containing CO2 is sucked into the air inlet through the built-in fan and pipeline. The collected dirty air gas enters 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 generated by the reaction. The ammonium carbonate generated after the CO2 absorption is saturated is transported to the CO2 desorption device 2-3 through the valve II 2-10. 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 air inlet valve 2-12 for recycling, and the ammonia water solution is re-proportioned. The ammonia water solution is supplemented into the CO2 absorption device 2-2 through the pipeline through 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 to store the liquid CO2 in the liquid CO2 storage tank 2-8. Among them, the chemical reaction formulas involved are as follows: CO2(g)+2NH4OH(aq)→(NH 4)2 CO3(aq)+H2O(l).

[0031] (NH4)2CO3(s)→2NH3(g)+CO2(g)+H2O(l).

[0032] 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 Ⅴ 3-3, 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 transmission pipe 3-9. First, conduct inspections and debugging 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 Ⅴ 3-3 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 transmission pipe 3-9 to effectively drain the underground gas to the ground.

[0033] As Figure 4As shown in the figure, when the internal temperature of the goaf rises abnormally or smoke appears, the used liquid-phase CO2 fire prevention and extinguishing module 4 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 of 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.

[0034] Furthermore, when adding water to the remaining purified gaseous CO2 and mixing it with gangue, when collecting gangue first, collect the images of coal and gangue on the coal conveyor belt, perform denoising, contrast enhancement, gray-scale analysis, texture feature extraction, and edge detection technology 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, and automatically identify the gangue through the identification model. When the gangue on the coal conveyor belt is identified, automatically grab the gangue and collect the gangue.

[0035] As Figure 5As shown in the figure, when mineralizing and storing 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 shearer and subjected to primary crushing 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 images 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. It is mixed by the stirrer 5-11, and 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.

[0036] As Figure 6As shown in the figure, when processing carbonate minerals into a fluid paste filling material and finally transporting the paste filling material to the goaf to complete the mineralization and storage of purified gaseous CO2, the goaf filling and storage module 6 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, and start the control and pumping device 6-6 to 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.

[0037] Furthermore, as Figure 2 shown, 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 air roadway. When the CO2 concentration in the mine return air roadway is monitored to be abnormal, different CO2 warning signals are issued. When the CO2 concentration in the mine return air roadway exceeds 0.75%, a flash alarm is issued; when the CO2 concentration in the return air current of the mining area exceeds 1.00%, a sound alarm message is issued; when the CO2 concentration in the return air current 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 a spacing of no more than 50 cm.

[0038] Furthermore, 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.

[0039] 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 case 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 maximum extent.

[0040] 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 to 4 h.

[0041] 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.

[0042] 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 still 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 capture - geological utilization - mineralization sequestration of CO2 in 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: 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. 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 fluid paste filling material to fill the goaf.

2. The integrated method for direct CO2 capture - geological utilization - mineralization and storage in mines according to claim 1, characterized in that, 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 and environmental parameters including temperature, humidity, air pressure, PM2.5 particle concentration, and oxygen concentration in the mine return airway in the environment. 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.

3. The integrated method for direct CO2 capture - geological utilization - mineralization and storage in a mine according to claim 2, wherein 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 mining area return airway exceeds 1.00%, a sound alarm message is issued. When the CO2 concentration in the mining area return airway exceeds 1.25%, both flash and sound alarm messages are sent simultaneously.

4. The integrated method for direct capture - geological utilization - mineralization and storage of CO2 in mines according to claim 2, 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.

5. The integrated method for direct capture - geological utilization - mineralization and storage of CO2 in coal mines according to claim 1, characterized in that 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. Use the extracted characteristic 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, automatically grab the gangue and collect the gangue.

6. The integrated method for direct capture - geological utilization - mineralization and storage of CO2 in mines according to claim 1, characterized in that, 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.

7. 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 fluid paste filling material, mix cement, binder, fly ash, thickener, water reducer, and carbonate minerals.

Images