An experimental apparatus for simulating CO2 mineralization in a goaf and its usage method

Abstract

The present application relates to the technical field of CO2 mineralization and disaster control in coal mine goaf, and proposes a device for simulating CO2 mineralization in goaf and a use method thereof.The device comprises a reaction box, a gas injection system, a material injection system, a gas extraction system and a monitoring system.The device can simulate CO2 mineralization experiments under different temperature, humidity, pressure and wind speed conditions in the goaf, and through real-time monitoring of the changes of pH value, temperature, humidity, pressure and gas concentration in the reaction device, the visualization of the whole process of CO2 mineralization and the plugging effect in the goaf is realized, and the process parameters for CO2 mineralization, plugging, fire prevention and extinguishing in the goaf are provided.

Description

Technical Field

[0001] This invention relates to the field of CO2 mineralization and coal mine goaf treatment technology, and in particular to an experimental device and method for simulating CO2 mineralization in goaf areas. Background Technology

[0002] CO2 sequestration provides an effective way to achieve the "dual carbon" goal. With the large-scale mining of coal mines and the formation of large-scale goaf areas, CO2 sequestration using coal mine goaf areas has been widely studied. At present, its technical routes mainly include directly utilizing the huge space of the goaf area for CO2 sequestration and using materials that can absorb CO2 for CO2 mineralization sequestration. Among them, CO2 mineralization sequestration provides a stable and leak-free method for fixing CO2, and does not even require long-term monitoring.

[0003] Large quantities of industrial solid waste, such as fly ash and carbide slag, are ideal raw materials for CO2 mineralization. By filling industrial solid waste into goaf areas and injecting CO2, a mineralization reaction can be achieved, which can achieve the triple effect of industrial solid waste treatment, CO2 emission reduction and goaf treatment. The mineralized carbonate products are also expected to achieve the effect of preventing and extinguishing fires caused by residual coal in goaf areas.

[0004] Current research on the mineralization of industrial solid waste and CO2 mainly focuses on laboratory conditions, with commonly used instruments including reactors and fluidized beds. However, given the unique conditions of goaf areas, such as high humidity, air leakage, and the presence of large amounts of coal-rock mixtures, existing experimental setups struggle to simulate goaf conditions for conducting mineralization experiments on industrial solid waste and CO2, leading to significant discrepancies between actual and experimental results. Summary of the Invention

[0005] Based on the shortcomings of the prior art, this invention provides an experimental device and method for simulating CO2 mineralization in goaf areas, which can realize real-time observation of the CO2 mineralization process under simulated goaf conditions of humidity, temperature, pressure and wind speed, and explore the CO2 mineralization process under goaf conditions.

[0006] To achieve the above-mentioned objectives, the following technical solution is adopted:

[0007] An experimental device for simulating CO2 mineralization in a goaf includes a reaction chamber, a gas injection system, a material injection system, a gas extraction system, and a monitoring system.

[0008] The reaction chamber includes a base and an outer shell. The base is supported below the outer shell. The outer shell is provided with a viewing glass window. The interior of the outer shell is the reaction chamber. A top partition is installed at the top of the reaction chamber. The reaction chamber contains packing material.

[0009] The reaction chamber has several air injection holes at the top of its outer shell, several grout injection holes on the left side wall, and several air extraction holes on the right side wall; as needed, the holes are arranged in one or more rows.

[0010] The gas injection system includes a gas cylinder, which is connected to one of the gas injection ports of the reaction chamber via a gas injection pipe, wherein a gas flow meter is installed on the gas injection pipe.

[0011] The material injection system includes an injection machine, which is connected to one of the injection holes on the left side wall of the reaction tank via an injection pipe;

[0012] The air extraction system includes an air extraction pump, which is connected to the air extraction port on the right side wall of the reaction chamber via an air extraction pipe.

[0013] The monitoring system includes a temperature monitoring module, a pressure monitoring module, a pH monitoring module, a gas concentration monitoring module, a humidity monitoring module, and a camera. The camera, temperature monitoring module, pressure monitoring module, pH monitoring module, gas concentration monitoring module, and humidity monitoring module are installed on one side of the reaction chamber. The camera, temperature monitoring module, pressure monitoring module, pH monitoring module, gas concentration monitoring module, humidity monitoring module, and camera are all connected to the computer system via network connection cables and transmit the monitored data to the computer system. After receiving the data information, the computer system remotely controls the gas injection system, material injection system, gas extraction system, and monitoring system.

[0014] All air injection holes, grout injection holes, and air extraction holes are equipped with sealing caps or valves. Unused air injection holes, grout injection holes, and air extraction holes are sealed. When in use, they are opened and connected to the corresponding pipelines. Both the sealing and the connection are airtight.

[0015] Preferably, an atomizing nozzle is installed downward in the center of the top partition, and each air injection hole is connected to the atomizing nozzle through an air hole channel; a heating component is laid at the bottom of the reaction chamber.

[0016] Preferably, except for the area where the viewing glass window is installed, the outer shell of the chamber is fitted with insulation material between itself and the reaction chamber; the insulation material is rigid polyurethane foam or ultrafine glass fiber cotton. Insulation material is also laid at the bottom of the reaction chamber.

[0017] Preferably, there are two gas cylinders, one containing CO2 and the other N2, with a gas flow rate of 0.1 L / min to 1 L / min.

[0018] Preferably, the temperature monitoring module includes two temperature sensors, one of which is installed at the center of the packing and the other is installed in the space outside the packing in the reaction chamber, to monitor the temperature of the reaction chamber and the packing respectively;

[0019] The humidity monitoring module includes two humidity sensors, one of which is installed at the center of the packing and the other is installed in the space outside the packing in the reaction cavity, to monitor the humidity of the reaction cavity and the packing respectively.

[0020] Preferably, the pressure monitoring module includes three pressure sensors, which are respectively arranged at the front, middle and rear of the packing to monitor the pressure at the front, middle and rear of the packing.

[0021] The pH monitoring module includes three pH probes, which are respectively placed at the front, middle and rear of the packing material to monitor the pH value at the front, middle and rear of the packing material.

[0022] Preferably, the gas concentration monitoring module includes a CO2 concentration sensor arranged in the reaction chamber to monitor the CO2 concentration in the reaction chamber.

[0023] Preferably, the outer casing has a viewing glass window on at least one side, and the rear of the outer casing has an openable door for loading and unloading packing. The viewing glass window may be located on the front of the outer casing, or on the front and sides, or on a portion of the front and top surfaces, or on a portion of the front, sides, and top surfaces.

[0024] Preferably, the camera is equipped with a foldable connecting arm, with its shooting angle facing the viewing glass window to capture images of the internal conditions of the cavity. The camera used is a high-speed camera.

[0025] The foldable connecting arm includes at least two connecting rods and two universal joints, and also has a base for mounting on the reaction chamber. The universal joint is mounted on the base, followed by connecting rods, universal joints, and connecting rods in sequence. The end of the outermost connecting rod has a connection part for placing the camera. The base and universal joints, and the universal joints and connecting rods are connected by pins, allowing for folding or extension in different directions to adjust the camera's shooting angle. However, it cannot slide freely; manual adjustment or activation of the automatic adjustment device is required.

[0026] A method for using a simulated CO2 mineralization experimental device in a goaf, comprising the following steps:

[0027] 1) Determine the conditions of the goaf: Obtain the temperature, humidity, pressure and wind speed conditions within the goaf through on-site investigation;

[0028] 2) Reaction chamber condition setting: Fill the reaction chamber with packing material. Based on the obtained goaf condition parameters, adjust the humidity through atomizing nozzles, adjust the temperature through heating components, and adjust the pressure and wind speed through the exhaust system to make the parameters in the reaction chamber meet the conditions in the goaf. The packing material used is fly ash, which contains a certain mass fraction of CaO and MgO.

[0029] 3) Material injection: The injection material is injected into the reaction cavity through the material injection system, and the injection process is observed through a visual glass window until the material completely covers the coal and rock filler; the injection material includes any one of slurry, gel, foam, or foam gel.

[0030] 4) Gas injection: Determine the gas injection location, inject gas, control the gas injection rate, and monitor the gas concentration in the reaction chamber at the same time;

[0031] 5) Mineralization reaction process: The flow of the injection material in the filler is captured by a camera through a visual glass window. The pH value, temperature, humidity, pressure and gas concentration changes during the reaction are monitored by a monitoring system. Once the measured parameters stabilize, the mineralization reaction is considered complete. The CO2 mineralization rate is calculated based on the pH value and gas concentration changes.

[0032] The calculation formulas are as follows (1)-(2):

[0033] pH method:

[0034]

[0035] Where χ is the mineralization rate, %; ΔpH is the average pH change at the front, middle and rear of the packing; X1 is the mass fraction of CaO in the packing, %; X2 is the mass fraction of MgO in the packing, %; M is the mass of the packing, g; e is a constant, logarithmic calculation symbol;

[0036] CO2 concentration method:

[0037]

[0038] Where χ represents the mineralization rate, in %; X1 represents the change in CO2 concentration; V represents the volume of the reaction chamber; X2 represents the mass fraction of CaO in the packing material (%); X3 represents the mass fraction of MgO in the packing material (%); M represents the mass of the packing material (g).

[0039] By using existing technology to analyze the composition of fly ash, the mass fractions of CaO and MgO can be obtained.

[0040] 6) Leakage plugging effect study: By recording the dynamic changes of pressure values ​​at the front, middle and rear of the filler before injection of the injection material in step 3) and after the mineralization reaction process in step 5) over time, the leakage plugging effect of CO2 mineralization material was obtained.

[0041] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0042] (1) It can conduct CO2 mineralization experiments under simulated goaf temperature, humidity, pressure and wind speed conditions, providing an experimental basis for CO2 mineralization in goaf.

[0043] (2) By redesigning the mineralization device and taking into account the special environmental factors of the goaf, the problem that traditional CO2 mineralization experimental instruments are difficult to optimize CO2 mineralization parameters under goaf conditions has been solved.

[0044] (3) By monitoring the changes in pH, temperature, humidity, pressure and gas concentration in the reaction device, and by using a high-speed camera to observe the mineralized materials, the entire process of CO2 mineralization under goaf conditions can be visualized, which is convenient for exploring the mineralization reaction conditions and mechanisms.

[0045] (4) In addition to mineralization experiments, this experimental device can also conduct experiments on sealing leaks in mineralization materials and fire prevention and extinguishing experiments on the low-temperature oxidation process of coal, providing a new method for fire prevention and extinguishing in coal mine goaf areas. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the experimental apparatus of the present invention;

[0047] 1. Gas cylinder; 2. Gas flow meter; 3. Injector; 4. Reaction chamber; 5. Grouting valve; 6. Box base; 7. Grouting hole; 8. Packing material; 9. Heating assembly; 10. Top partition; 11. Box shell; 12. Atomizing nozzle; 13. Exhaust port; 14. Exhaust pump; 15. Camera; 16. Temperature monitoring module; 17. Pressure detection module; 18. pH monitoring module; 19. Gas concentration monitoring module; 20. Humidity monitoring module; 21. Computer system; 22. Grouting pipeline; 23. Exhaust pipeline; 24. Exhaust valve; 25. Wiring network; 26. Gas injection pipeline.

[0048] Figure 2 This is a diagram showing the effect after the material of this invention has been injected. Detailed Implementation

[0049] The accompanying drawings are for illustrative purposes only and should not be construed as limiting the invention. To better illustrate this embodiment, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. Terms such as "upper," "lower," "top," "bottom," "side," "outer," "front," and "back" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the invention and simplifying the description, not to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the invention. For those skilled in the art, some well-known structures and their descriptions in the drawings may be omitted.

[0050] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0051] Example 1

[0052] like Figure 1 An experimental device for simulating CO2 mineralization in a goaf includes a reaction chamber, a material injection system, a gas injection system, a gas extraction system, and a monitoring system.

[0053] The reaction chamber includes a base 6 and an outer shell 11. The outer shell 11 has a viewing glass window on its front. Inside the outer shell 11 is a reaction cavity 4, which contains packing material 8, a coal-rock mixture with a mixing ratio of 4:1. A camera 15 is mounted outside the reaction chamber via a foldable connecting arm. The foldable connecting arm includes two connecting rods and two universal joints, and is mounted on the reaction chamber via the base. The connecting arm can be manually adjusted to fold or extend in different directions, thereby adjusting the camera's shooting angle to observe the air leakage situation of the CO2 mineralization material in the reaction cavity.

[0054] Except for the side with the viewing glass window, the outer shell 11 of the chamber is insulated from the reaction chamber 4. A small door is provided on the back of the outer shell 11 for filling the packing material 8. The door is also insulated and can be sealed with the outer shell.

[0055] A top-layer partition 10 is installed at the top of the reaction chamber 4, and several gas injection holes are provided at the top of the reaction chamber 4. Figure 1 (Omitted) The number of air injection holes is 10, and each hole is fitted with a sealing cap, allowing them to be opened or closed. The left side wall of the outer casing has 5 grouting holes, and the right side wall has 5 air extraction holes, all fitted with sealing caps, allowing them to be opened or closed. The filling height of the filler 8 is variable, and the selection of the grouting holes 7 and air extraction holes 13 varies depending on the filling height of the filler 8.

[0056] The gas injection system includes two gas cylinders, one containing CO2 and the other N2, with a gas flow rate of 0.5 L / min. The gas pipelines from the two cylinders are connected together, and each pipeline is equipped with a valve and a gas flow meter. Depending on the experimental conditions, the type of gas injected can be selected according to actual requirements, including pure CO2, pure N2, and mixtures of CO2 and N2 in different proportions. For example, if the injected gas is flue gas, the CO2 concentration is adjusted to 15%-20%, and the N2 concentration to 80%-85%. If the injected gas is CO2, only the CO2 cylinder valve is opened for injection; if the injected gas is N2, only the N2 cylinder valve is opened for injection. Gas cylinders 1 are connected to one of the injection ports of the reaction chamber via injection pipeline 26. The injection pipeline 26 is fitted to the injection port to ensure a tight connection. A gas flow meter 2 is installed on the injection pipeline 26 to monitor the amount of gas injected.

[0057] The left side of the reaction chamber is connected to a material injection system, which includes an injection machine 3. The injection machine 3 is connected to one of the grouting holes 7 on the left side wall of the reaction chamber via an injection pipe 22. The injection pipe 22 and the grouting hole are compatible and can achieve a tight connection. A grouting valve 5 is installed on the injection pipe 22.

[0058] The right side of the reaction chamber is connected to an extraction system, which includes an extraction pump 14. The extraction pump 14 is connected to an extraction port 13 on the right side wall of the reaction chamber via an extraction pipe 23. The extraction pipe 23 and the extraction port 13 are compatible and can be tightly connected. An extraction valve 24 is installed on the extraction pipe 23.

[0059] The monitoring system includes a temperature monitoring module 16, a pressure monitoring module 17, a pH monitoring module 18, a gas concentration monitoring module 19, a humidity monitoring module 20, and a camera 15, which is a high-speed camera. The camera 15, temperature monitoring module 16, pressure monitoring module 17, pH monitoring module 18, gas concentration monitoring module 19, and humidity monitoring module 20 are connected to a computer system 21 via network cables 25, and transmit the monitored data to the computer system 21. The computer system can remotely control the gas injection system, material injection system, extraction system, and monitoring system, and can activate the gas injection system, material injection system, and extraction system as needed to adjust the required temperature, humidity, pressure, and airflow conditions of the reaction chamber.

[0060] As a further preferred configuration, an atomizing nozzle 12 is installed downwards in the center of the top partition 10, and each gas injection hole is connected to the atomizing nozzle 12, which can uniformly spray gas into the reaction chamber 4; a heating component 9 is laid in the insulation material at the bottom of the reaction chamber 4. The heating component 9 consists of a heater and a heating element. The heater is controlled by a computer system and can heat the bottom of the reaction chamber 4 to maintain the temperature of the reaction chamber at the required temperature. The temperature range that can be heated is 30-70℃.

[0061] The insulation material is ultra-fine glass fiber cotton.

[0062] Temperature monitoring module 16 includes two temperature sensors, respectively located in the reaction chamber 4 (space excluding packing) and the center of packing 8, to monitor the temperature T1 of reaction chamber 4 and the temperature T2 of packing 8, respectively; pressure monitoring module 17 includes three pressure sensors, respectively located in front, middle, and rear of packing 8, to monitor the pressures P1, P2, and P3 in front, middle, and rear of packing 8, respectively; gas concentration monitoring module 19 includes a CO2 concentration sensor, located in reaction chamber 4, to monitor the CO2 concentration C in reaction chamber 4; pH monitoring module 18 includes three pH probes, respectively located in front, middle, and rear of packing 8, to monitor the pH values ​​pH1, pH2, and pH3 in front, middle, and rear of packing 8, respectively; humidity monitoring module 20 includes two humidity sensors, respectively located in reaction chamber 4 (space excluding packing) and inside packing 8, to monitor the humidity W1 and W2 inside reaction chamber 4 and inside packing 8, respectively; a high-speed camera is located on the front of the reaction chamber, facing the viewing glass window. Data from each monitoring module in the monitoring system and images captured by high-speed cameras are transmitted to computer system 21 via line network 25 for real-time display, facilitating real-time control by the computer system.

[0063] The steps for using this device are as follows:

[0064] 1) Determine the conditions of the goaf: Obtain the temperature, humidity, pressure and wind speed conditions within the goaf through on-site investigation.

[0065] 2) Reaction chamber condition settings: Fill the reaction chamber 4 with packing material 8, turn on the atomizing nozzle 12, and observe the change of humidity value W1 in the reaction chamber 4 through the computer system 21; set the heating temperature of the heating component 9 through the computer system 21, and monitor the change of temperature value T1 in the reaction chamber 4 at the same time.

[0066] Turn on the air pump 14 and set the air pumping rate of the air pump 14 according to the wind speed conditions in the goaf. When the parameters in the reaction chamber meet the conditions in the goaf, proceed to the next step and turn off the atomizing nozzle at the same time.

[0067] 3) Material injection: The material is injected into the reaction cavity 4 through the material injection system. The injection material is fly ash-based foam gel. The material injection is observed through a visual glass window until the material completely covers the coal and rock filler 8.

[0068] 4) Gas injection: Determine the gas injection location. Taking the left side as an example, close the right opening of the top partition 10. Take pure CO2 as an example for the injection gas. Open CO2 cylinder 1, adjust the gas flow meter 2 to control the gas injection rate, and monitor the CO2 gas concentration in the reaction chamber at the same time. When the CO2 gas concentration is 1.5 mol / L, close cylinder 1 and stop the gas injection.

[0069] During the experiment, the injection position can be controlled by opening and closing the opening on the top partition 10. If left-side injection is selected, the right-side opening of the top partition 10 can be closed, allowing CO2 gas to be injected from the left side of the reaction chamber 4; if right-side injection is selected, the left-side opening of the partition can be closed; injection in the middle can also be selected. The target concentration of CO2 gas after injection is variable and controlled by the injection time.

[0070] 5) Mineralization reaction process: A high-speed camera is used to capture the flow of fly ash-based foam gel in the coal-rock mixture through a visualization glass window. The pH value, temperature, humidity, pressure and gas concentration changes during the reaction are monitored by a monitoring system. Once the measured parameters stabilize, the mineralization reaction is considered complete. The CO2 mineralization rate is calculated based on the pH value and gas concentration changes.

[0071] 6) Leakage plugging effect study: By recording the dynamic changes of the pressure values ​​P1, P2, and P3 of the filler (8) before the injection of the material in step 3) and after the mineralization reaction process in step 5) over time, the leakage plugging effect of the CO2 mineralization material was obtained. Figure 2 The image shown is a photograph of the effect after the material was poured in.

[0072] Example 2

[0073] Heating component 9 consists of a heater and a heating oil pipe, with the heating oil pipe filled with heating oil. Automatic valves are installed at each air injection hole, grout injection hole 7, and air extraction hole. Operation is controlled by opening and closing these automatic valves.

[0074] During gas injection, a mixture of CO2 and N2 in different ratios is injected, with the CO2 concentration adjusted to 15% and the N2 concentration to 85%.

[0075] The outer casing 11 has viewing glass windows on the front and upper right side. A camera 15 is mounted outside the reaction chamber via a foldable connecting arm. The foldable connecting arm includes three connecting rods and three universal joints, and is mounted on the reaction chamber via a base. The connecting arm can be manually adjusted to fold or extend in different directions, allowing for shooting from the front or side of the outer casing, thus adjusting the camera's shooting angle to observe the air leakage situation of the CO2 mineralization material inside the reaction chamber. When not shooting, it can be folded away to reduce space occupation.

[0076] Other areas not mentioned are the same as in Example 1.

[0077] Example 3

[0078] During gas injection, a mixture of CO2 and N2 in different ratios is injected, with the CO2 concentration adjusted to 10% and the N2 concentration to 90%.

[0079] A portion of the front and top surfaces of the outer casing 11 are fitted with viewing glass windows, while the corresponding top position of the reaction chamber 4 lacks a top partition. The number of air injection holes can be set as needed, ranging from 4 to 8. Viewing glass windows are installed where no air injection holes or air passages are present. A camera 15 is mounted outside the reaction chamber via a foldable connecting arm. The foldable connecting arm comprises three connecting rods and three universal joints, mounted on the reaction chamber via a base. The connecting arm adopts a robotic arm design from existing technology. Each connecting rod and universal joint is equipped with a sensor, motor, and connecting cable. Its position can be automatically adjusted via a computer system 21 to achieve folding or extension in different directions. It can capture images from the front of the outer casing or directly facing the top viewing glass window to observe the air leakage situation of the CO2 mineralization material in the reaction chamber. When not in use, it can be folded away to reduce space occupation.

[0080] Other areas not mentioned are the same as in Example 1.

[0081] Example 4

[0082] 1) The reaction chamber 4 and the packing 8 are heated by the heating component 9, and the temperature is set to 70℃. The temperature T1 of the reaction chamber 4 and the temperature T2 of the packing 8 are monitored by the temperature monitoring module to show the temperature change of the coal body in the low-temperature oxidation process before the reaction.

[0083] 2) Conduct CO2 mineralization experiments, as in Example 1;

[0084] 3) Repeat step (1) again and monitor the temperature change to show the temperature change during the low-temperature oxidation process of the coal after the reaction;

[0085] 4) By comparing the temperature changes of the coal body during the low-temperature oxidation process before and after the reaction, the effectiveness of the method for preventing spontaneous combustion of residual coal in goaf based on CO2 mineralization was obtained, providing a new method for fire prevention and extinguishing in coal mine goaf.

[0086] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0087] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A method for using a simulated CO2 mineralization experimental device in a goaf, characterized in that, The device includes a reaction chamber, a gas injection system, a material injection system, a gas extraction system, and a monitoring system; The reaction chamber includes a base and an outer shell. The base is supported below the outer shell. The outer shell is provided with a viewing glass window. The interior of the outer shell is the reaction chamber. A top partition is installed at the top of the reaction chamber. The reaction chamber contains packing material. The reaction chamber has several air injection holes at the top of its outer shell, several grout injection holes on the left side wall, and several air extraction holes on the right side wall. The gas injection system includes gas cylinders, which are connected to one of the gas injection ports of the reaction chamber via gas injection pipes. A gas flow meter is installed on the gas injection pipes. There are two gas cylinders, one containing CO2 and the other containing N2, with a gas flow rate of 0.1 L / min to 1 L / min. The material injection system includes an injection machine, which is connected to one of the injection holes on the left side wall of the reaction tank via an injection pipe; The air extraction system includes an air extraction pump, which is connected to the air extraction port on the right side wall of the reaction chamber via an air extraction pipe. The monitoring system includes a temperature monitoring module, a pressure monitoring module, a pH monitoring module, a gas concentration monitoring module, a humidity monitoring module, and a camera. The camera, temperature monitoring module, pressure monitoring module, pH monitoring module, gas concentration monitoring module, and humidity monitoring module are installed on one side of the reaction chamber. The camera, temperature monitoring module, pressure monitoring module, pH monitoring module, gas concentration monitoring module, humidity monitoring module, and camera are connected to the computer system via network connection cables and transmit the monitored data to the computer system. After receiving the data information, the computer system remotely controls the gas injection system, material injection system, gas extraction system, and monitoring system. The gas concentration monitoring module includes a CO2 concentration sensor arranged in the reaction chamber to monitor the CO2 concentration inside the reaction chamber; the camera is equipped with a foldable connecting arm, and its shooting angle faces the viewing glass window; The method of use includes the following steps: 1) Determine the conditions of the goaf: Obtain the temperature, humidity, pressure and wind speed conditions within the goaf through on-site investigation; 2) Reaction chamber condition setting: Fill the reaction chamber with packing material, and adjust the humidity through the atomizing nozzle, adjust the temperature through the heating component, and adjust the pressure and wind speed through the exhaust system according to the obtained goaf condition parameters, so that the parameters in the reaction chamber meet the conditions in the goaf. 3) Material injection: The injection material is injected into the reaction cavity through the material injection system. The injection process is observed through a visual glass window until the material completely covers the coal and rock filler. The injection material includes any one of slurry, gel, foam, or foam-gel. 4) Gas injection: Determine the gas injection location, inject gas, control the gas injection rate, and monitor the gas concentration in the reaction chamber at the same time; 5) Mineralization reaction process: The flow of the injection material in the filler is captured by a camera through a visual glass window. The pH value, temperature, humidity, pressure and gas concentration changes during the reaction are monitored by a monitoring system. Once the measured parameters stabilize, the mineralization reaction is considered complete. The CO2 mineralization rate is calculated based on the gas concentration changes. The calculation formula is as follows (1): （1）； Where χ represents the mineralization rate, %; V represents the change in CO2 concentration, mol / L; V is the volume of the reaction chamber, L; X1 is the mass fraction of CaO in the packing, %; X2 is the mass fraction of MgO in the packing, %; M is the mass of the packing, g; 6) Leakage plugging effect study: By recording the dynamic changes of pressure values ​​at the front, middle and rear of the filler before injection of the injection material in step 3) and after the mineralization reaction process in step 5) over time, the leakage plugging effect of CO2 mineralization material is obtained.

2. The method of using the experimental device for simulating CO2 mineralization in a goaf area as described in claim 1, characterized in that, An atomizing nozzle is installed downwards in the center of the top partition, and each air injection hole is connected to the atomizing nozzle; a heating assembly is laid at the bottom of the reaction chamber.

3. The method of using the experimental device for simulating CO2 mineralization in a goaf area as described in claim 2, characterized in that, Except for the area where the viewing glass window is installed, the outer shell of the chamber is fitted with thermal insulation material between itself and the reaction chamber; the thermal insulation material is rigid polyurethane foam or ultra-fine glass fiber cotton.

4. The method of using the experimental device for simulating CO2 mineralization in a goaf area as described in claim 1, characterized in that, The temperature monitoring module includes two temperature sensors, one installed at the center of the packing and the other installed in the space outside the packing in the reaction chamber, to monitor the temperature of the reaction chamber and the packing respectively; the humidity monitoring module includes two humidity sensors, one installed at the center of the packing and the other installed in the space outside the packing in the reaction chamber, to monitor the humidity of the reaction chamber and the packing respectively.

5. The method of using the experimental device for simulating CO2 mineralization in a goaf area as described in claim 1, characterized in that, The pressure monitoring module includes three pressure sensors, which are respectively arranged at the front, middle and rear of the packing material to monitor the pressure at the front, middle and rear of the packing material; the pH monitoring module includes three pH probes, which are respectively arranged at the front, middle and rear of the packing material to monitor the pH value at the front, middle and rear of the packing material.

6. The method of using the experimental device for simulating CO2 mineralization in a goaf area as described in claim 1, characterized in that, The outer shell of the enclosure is provided with a viewing glass window on at least one side, and the back of the enclosure has an openable door for loading and unloading packing.

Images