Carbon dioxide circulation mineralization grouting equipment and method for gas extraction hole sealing

Abstract

The application discloses a kind of carbon dioxide circulation mineralization slurry preparation and grouting equipment and method for gas extraction hole sealing, belong to coal mine gas extraction hole sealing technical field.The equipment includes CO2 gas supply unit, slurry preparation and mineralization unit, buffer anti-settling unit and grouting unit integrated on skid-mounted platform.Slurry preparation and mineralization unit is provided with stirring assembly and bottom disc aerator, for preparing low-carbon hole sealing slurry on site and dispersing CO2 in the form of bubble into slurry;Unreacted CO2 is sent to gas-liquid separation tank by circulation outlet valve after removing entrained liquid drops, and is sent back to disc aerator by CO2 circulation pump and circulation inlet valve, to realize closed-circuit mineralization.Slurry after mineralization is sent to buffer slurry tank provided with anti-settling stirrer by slurry outlet valve, to maintain uniform state, and then is sent to coal seam hole sealing section by grouting pump through grouting pipe.The application integrates slurry preparation, mineralization, buffering and grouting, reduces transfer link, and significantly improves CO2 utilization rate and hole sealing construction continuity.

Description

Technical Field

[0001] This invention relates to the technical fields of coal mine gas drainage borehole sealing, low-carbon cementitious material preparation, carbon dioxide mineralization utilization, and on-site grouting equipment, specifically to a carbon dioxide circulating mineralization grouting equipment and method for gas drainage borehole sealing. Background Technology

[0002] Gas drainage is a crucial technical means for controlling gas disasters in coal mines and utilizing coalbed methane resources. The quality of borehole sealing directly affects the gas drainage concentration, the stability of the drainage negative pressure, and the effective service life of the borehole. Currently, most gas drainage borehole sealing materials are cement-based slurries, expansive cement slurries, or organic sealing materials. Cement-based sealing slurries have advantages such as wide availability of raw materials, low cost, high strength, and convenient construction. However, during the hardening process, they are prone to shrinkage, cracking, interface debonding, and pore connectivity, leading to leakage channels in the sealed section and affecting gas drainage efficiency. To reduce the amount of cement in sealing materials and improve their low-carbon properties, solid wastes such as fly ash, slag, and coal gangue powder are increasingly being used to prepare cement-based or composite cementitious sealing slurries. However, this may also lead to insufficient early-stage reactivity, slow strength development, and inadequate structural densification.

[0003] To address the aforementioned issues, CO2 mineralization technology has been introduced into the field of borehole sealing grout preparation. This technology enables CO2 to react with alkaline components such as calcium and magnesium in cement-based materials or solid waste materials, generating stable carbonate minerals, thereby improving the pore structure and mechanical properties of the materials. However, there are still significant shortcomings in the integration between existing CO2 mineralization grout preparation and on-site borehole sealing construction in coal mines. On the one hand, conventional CO2 mineralization processes are mostly carried out in independent reaction equipment or laboratory devices, and the mineralized grout still needs to be transported to the on-site grouting equipment, which can easily cause grout sedimentation, segregation, performance fluctuations, and pipe blockage. On the other hand, if CO2 is directly introduced into the grout on-site, unreacted gases easily escape, the residence time of CO2 in the grout is short, and the mineralization utilization efficiency is very limited. In addition, the on-site grouting process requires the grout to continuously and stably enter the grouting pump. Without buffering and anti-settling measures, unstable grout supply, grouting interruption, pressure fluctuations, and uneven filling of the sealing section can easily occur.

[0004] In summary, existing technologies separate the preparation of low-carbon sealing slurry, CO2 mineralization modification, and borehole grouting and sealing processes. There is a lack of integrated on-site equipment that can highly integrate these processes, achieve efficient closed-loop CO2 recycling, and provide slurry buffering and anti-settling functions. Therefore, developing a skid-mounted integrated equipment and process that can solve the problems of process separation, low CO2 utilization, and discontinuous grouting has become a pressing technical challenge in this field. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a carbon dioxide circulating mineralization grouting equipment and method for gas extraction sealing.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This application provides a carbon dioxide circulating mineralization slurry preparation and injection equipment for sealing gas extraction wells, including a gas supply unit, a slurry preparation and circulating mineralization unit, a buffer and anti-settlement unit, and an injection unit; The gas supply unit, pulping and circulating mineralization unit, buffer and anti-settling unit and grouting unit are all integrated on the skid-mounted platform; The gas supply unit is used to supply carbon dioxide gas to the pulping and circulating mineralization unit; The pulping and circulating mineralization unit includes a pulping and circulating mineralization tank, which is used to mix solid raw materials with mixing water to prepare low-carbon sealing slurry, and to use the carbon dioxide gas to perform circulating mineralization modification on the low-carbon sealing slurry. The buffer anti-settling unit includes a buffer slurry tank, which is connected to the pulping and circulating mineralization unit. It is used to temporarily store the mineralized and modified slurry and maintain the uniform dispersion of the slurry before injection. The grouting unit includes a grouting pump, which is connected to the buffer and anti-settlement unit and is used to pressurize and transport the grout in the buffer and anti-settlement unit to the sealing section of the coal seam.

[0007] Preferably, the pulping and circulating mineralization unit further includes a sealed flange feeding port, a water inlet valve, a mechanical seal, a stirring assembly, a disc aerator, a circulating air outlet valve, a gas-liquid separator, a CO2 circulating pump, a drain valve, a circulating air inlet valve, and a slurry outlet valve. The sealed flange feeding port and water inlet valve are installed on the pulping and circulating mineralization tank, and are used to add solid raw materials, mixing water and liquid additives, respectively. The stirring assembly is disposed inside the pulping and circulating mineralization tank, and the mechanical seal is provided at the part of the stirring assembly that passes through the pulping and circulating mineralization tank; The disc aerator is located at the bottom of the pulping and circulating mineralization tank and is connected to the air supply unit. The upper exhaust port of the pulping and circulating mineralization tank is connected to the gas-liquid separator through the circulating air valve. The liquid outlet of the gas-liquid separator is equipped with the drain valve, and the gas outlet is connected to the CO2 circulating pump. The CO2 circulating pump is connected to the disc aerator through the circulating air inlet valve, forming a gas circulation loop. The slurry outlet valve is located at the bottom slurry outlet of the slurry circulating mineralization tank.

[0008] Preferably, the gas-liquid separator is used to separate liquid droplets or slurry mist droplets entrained in the circulating gas. The separated liquid is discharged through the drain valve, and the separated carbon dioxide gas is transported through the CO2 circulating pump and returned to the disc aerator via the circulating air inlet valve.

[0009] Preferably, the buffer anti-settling unit further includes an anti-settling agitator; The anti-settling agitator is installed inside the buffer slurry tank and is used to slow down or prevent the settling and segregation of the slurry in the buffer slurry tank by low-speed agitation.

[0010] Preferably, the buffer slurry tank is further provided with a cleaning water inlet and a drain valve; The cleaning water inlet is used to introduce cleaning medium into the passage of the buffer slurry tank and the grouting unit; The drain valve is used to discharge sediment, residual slurry, or cleaning waste liquid from the bottom of the buffer slurry tank.

[0011] Preferably, the grouting unit further includes a grouting pipe; The outlet of the grouting pump is connected to the grouting pipe, and the grouting pipe is connected to the sealing section in the coal seam.

[0012] Preferably, the gas supply unit includes a CO2 cylinder, a cylinder pressure gauge, a pressure reducing valve, a gas mass flow controller, and an inlet valve; The outlet of the CO2 cylinder is connected in sequence to the cylinder pressure gauge, pressure reducing valve, gas mass flow controller and inlet valve; The air outlet of the air inlet valve is connected to the air inlet of the pulping and circulating mineralization unit.

[0013] A carbon dioxide circulating mineralization grouting method using the equipment described above includes the following steps: Step S1: After confirming that the equipment is in normal working condition, add solid raw materials into the pulping and circulating mineralization tank through the sealed flange feeding port, and add mixing water and liquid additives through the water inlet valve. Step S2: Start the stirring assembly to stir the material in the pulping and circulating mineralization tank to prepare a uniform low-carbon sealing slurry. Step S3: Open the CO2 cylinder to allow the CO2 gas to pass through the pressure reducing valve, gas mass flow controller and air inlet valve in sequence into the disc aerator, and disperse into the slurry to carry out the mineralization reaction. Step S4: Open the circulating air outlet valve, CO2 circulating pump and circulating air inlet valve so that the unreacted CO2 in the upper part of the pulping circulating mineralization tank is separated by the gas-liquid separator and then sent back to the disc aerator by the CO2 circulating pump to realize CO2 circulating mineralization. Step S5: After the mineralization reaction is completed, open the slurry outlet valve to allow the mineralized slurry to enter the buffer slurry tank, and start the anti-settling agitator to maintain the uniform dispersion of the slurry. Step S6: Start the grouting pump and transport the mineralized grout in the buffer grout tank to the sealing section of the coal seam through the grouting pipe to complete the grouting and sealing construction.

[0014] Preferably, in step S4, the circulating gas is separated into gas and liquid by a gas-liquid separator, and the trapped liquid is discharged by a drain valve.

[0015] Preferably, after step S6 is completed, cleaning water is introduced into the buffer slurry tank and grouting pipeline through the cleaning water inlet, and residual slurry or cleaning waste liquid is discharged through the drain valve; and / or, In step S5, the slurry is stirred at low speed using an anti-settling agitator, or a reflux pipe is installed in the buffer slurry tank to circulate the slurry back to maintain its uniformity.

[0016] Compared with the prior art, this application has the following beneficial effects: This invention proposes a carbon dioxide circulating mineralization grouting equipment and method for sealing gas extraction boreholes. It integrates low-carbon sealing slurry preparation, CO2 circulating mineralization, buffering and anti-settlement, and borehole grouting sealing onto a single skid-mounted device, fundamentally solving the problems of slurry transfer, settlement, and performance fluctuations caused by the separation of processes in traditional methods. The closed-loop recycling of unreacted CO2 through the gas circulation loop within the slurry preparation and mineralization unit significantly extends the effective residence time of CO2 in the slurry and substantially improves the mineralization utilization rate. Simultaneously, the buffering and anti-settlement unit provides a continuous and stable slurry source for the grouting pump, effectively reducing the risk of pipe blockage and interruption during grouting, ensuring the uniformity of filling the sealing section and the continuity of construction. Furthermore, the entire equipment is integrated on a skid-mounted platform, facilitating on-site transportation, movement, and deployment, greatly improving the convenience and engineering adaptability of underground sealing construction in coal mines. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a carbon dioxide circulating mineralization grouting equipment for sealing gas extraction wells according to the present invention.

[0018] In the diagram: 1-CO2 cylinder; 2-Cylinder pressure gauge; 3-Pressure reducing valve; 4-Gas mass flow controller; 5-Inlet valve; 6-Disc aerator; 7-Agitator assembly; 8-Mechanical seal; 9-Sealed flange feed port; 10-Water inlet valve; 11-Circulating air outlet valve; 12-Gas-liquid separator; 13-CO2 circulating pump; 14-Drain valve; 15-Pulping circulating mineralization tank; 16-Circulating air inlet valve; 17-Pulp outlet valve; 18-Anti-settling agitator; 19-Cleaning water inlet; 20-Buffer slurry tank; 21-Drain valve; 22-Skimmed platform; 23-Grouting pump; 24-Grouting pipe; 25-Sealing section; 26-Coal seam. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Furthermore, in this invention, an element referred to as fixed to or disposed on another element may be directly disposed on the other element, or there may be an intermediate element. When an element is considered to be connected to another element, it may be directly connected to the other element, or there may be an intermediate element present simultaneously. The terms vertical, horizontal, left, right, and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0021] The following is combined with Figure 1 The specific embodiments of the present invention will be described in detail below. It should be understood that the following embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Equivalent substitutions or adjustments made to the equipment structure, pipeline connection method, valve type, stirring structure and operation sequence without departing from the technical concept of the present invention shall all fall within the scope of protection of the present invention.

[0022] like Figure 1As shown, this embodiment provides a carbon dioxide circulating mineralization slurry preparation and grouting device for gas extraction and sealing. The device mainly consists of a CO2 gas supply unit, a slurry circulation mineralization unit, a buffer anti-settlement unit, and a grouting unit, and all of the above units are uniformly integrated and installed on a skid-mounted platform 22. The use of the skid-mounted platform 22 makes the whole set of equipment highly compact. As an integral base, it can perfectly adapt to the complex and narrow roadway space in coal mines or the surface construction site, which facilitates the overall hoisting, rapid movement and flexible arrangement using mining transport vehicles. It greatly reduces the auxiliary operation time for on-site equipment installation and dismantling, and effectively solves the construction problems of transporting multiple independent devices separately and cumbersome on-site pipeline connection in traditional technologies.

[0023] Specifically, the CO2 gas supply unit constitutes the power source of the entire equipment, mainly including a CO2 cylinder 1, a cylinder pressure gauge 2, a pressure reducing valve 3, a gas mass flow controller 4, and an inlet valve 5. The CO2 cylinder 1 stores high-pressure industrial-grade or food-grade carbon dioxide gas, providing a continuous source of reaction gas for the subsequent pulping and mineralization reaction. A cylinder pressure gauge 2 is directly installed at the outlet of the CO2 cylinder 1. This gauge displays the remaining pressure inside the cylinder and the supply pressure at the outlet in real time, allowing on-site operators to monitor the gas supply status and ensuring the safety and reliability of the gas supply process. The CO2 cylinder 1 is connected in series with the pressure reducing valve 3, the gas mass flow controller 4, and the inlet valve 5 via a high-pressure resistant gas supply pipeline. The main function of valve 3 is to reduce the pressure of the high-pressure gas output from CO2 cylinder 1 and adjust it to the optimal working pressure range suitable for subsequent mineralization reactions, so as to avoid excessive pressure causing impact on the equipment or insufficient reaction power due to excessively low pressure. After depressurization, the CO2 gas then enters the gas mass flow controller 4. This controller can accurately set and automatically maintain the input flow of CO2 according to the actual pulping volume and the needs of the mineralization reaction, thereby ensuring that the contact ratio between CO2 and slurry is in the optimal state. Finally, the CO2 gas, after precise pressure adjustment and flow control, enters the pulping circulation mineralization tank 15 through the air inlet valve 5. The air inlet valve 5 mainly plays the role of opening and closing control here, ensuring smooth opening when air is needed, and quickly cutting off the gas source during non-working periods or emergency situations.

[0024] The pulping and circulating mineralization tank 15 is the core equipment for on-site pulp preparation and CO2 mineralization modification. Its structural design takes into account both thorough mixing and efficient closed-loop reaction requirements. The top of the tank is equipped with a sealed flange inlet 9, which uses a flange connection and sealing gasket structure to provide excellent airtightness. This allows operators to quickly add cement, fly ash, mineral admixtures, expanding agents, or other solid powder raw materials into the tank, and ensures complete sealing after feeding by tightening the flange, thus effectively preventing... To prevent the subsequent CO2 gas from escaping from the feed port; a water inlet valve 10 is also provided at the top or upper part of the pulping and circulating mineralization tank 15. This valve is connected to an external water source pipeline and is used to quantitatively add the mixing water required for preparing the low-carbon sealing slurry into the tank; at the same time, in order to adapt to the slurry performance adjustment requirements under different working conditions, various liquid admixtures, such as water-reducing agents, early strength agents or retarders, can be added into the tank through the water inlet valve 10 or by setting an additional dedicated liquid feeding interface to improve the fluidity or early strength of the slurry.

[0025] A stirring assembly 7 is vertically installed at the center of the pulping and circulating mineralization tank 15. This stirring assembly 7 is driven by a drive motor located above the tank body. A mechanical seal 8 is installed where the stirring shaft passes through the top cover of the tank body. The mechanical seal 8 is a key structural component for achieving efficient mineralization sealing operation. Through the tight fit of the moving and stationary rings, it maintains extremely high sealing performance even when the stirring shaft is rotating at high speed, effectively preventing the slurry inside the tank from leaking out along the shaft sleeve. It also blocks external air from entering the tank, thus ensuring the entire mineralization reaction process can proceed smoothly. The process is carried out stably under a fully enclosed negative or slightly positive pressure environment, which effectively avoids the disorderly leakage of CO2 and lays a structural foundation for subsequent recycling and mineralization. In the actual pulping operation, the operator adds various solid raw materials, mixing water and liquid additives into the tank through the sealed flange feeding port 9 and water inlet valve 10. Then, the stirring component 7 is immediately started to carry out full mechanical stirring, so that the solid particles, water and chemical additives in the tank are quickly mixed, wetted and dispersed under strong shear force, and finally a low-carbon sealing slurry with good fluidity and highly uniform distribution of each component is formed.

[0026] To achieve efficient contact reaction between CO2 and slurry, a disc aerator 6 is arranged at the bottom of the pulping and circulating mineralization tank 15. This disc aerator 6 is directly connected to the upstream CO2 supply pipeline. When CO2 gas enters the bottom of the pulping and circulating mineralization tank 15 through the inlet valve 5, the high-pressure CO2 is converted into a large number of fine, uniformly distributed bubbles by the micropores or cutting action of the disc aerator 6, and directly diffuses into the interior of the prepared slurry inside the tank. During this process, due to the continuous generation of strong radial and axial turbulence by the stirring component 7 inside the tank, the slurry flow field is in a state of intense turbulence. This forces the rising CO2 bubbles from the bottom to be further sheared and broken into smaller microbubbles, which are then evenly distributed throughout the tank volume as the slurry circulates. This synergistic effect of bottom aeration and dispersion combined with top stirring and turbulence greatly increases the gas-liquid two-phase mass transfer contact area between CO2 gas and alkaline mineral components such as cement and fly ash in the slurry, and significantly shortens the path of gas diffusion and mass transfer into the liquid phase. Thus, it simultaneously improves the dissolution rate of CO2 and the speed of carbonate mineralization reaction at both the macroscopic and microscopic levels. This is an important technical guarantee for the efficient and low-carbon sealing of the pores in this invention.

[0027] To fundamentally solve the problems of excessive CO2 loss and short effective residence time in traditional direct aeration methods, one of the core innovations of this invention is the construction of a complete, closed-loop CO2 gas circulation and recovery system. Specifically, the upper space of the pulping and circulating mineralization tank 15 is equipped with a dedicated gas collection and exhaust port, which is connected to the circulation exhaust valve 11 through a pipeline. During the mineralization reaction, as the bottom is continuously aerated, a large amount of CO2 gas that has not dissolved or reacted in time will accumulate in the upper part of the tank. This unreacted CO2 gas is driven by the pressure inside the tank and enters the gas-liquid separator 12 through the circulation exhaust valve 11.

[0028] The gas-liquid separator 12 is a vertically positioned separation container. Its interior can be equipped with baffles or cyclone separation structures according to process requirements. When a mixed gas containing droplets or slurry mist enters the gas-liquid separator 12, under the combined action of gravity settling and centrifugal separation, the tiny water droplets and slurry droplets entrained in the gas are effectively trapped and settle to the bottom of the tank, while the pure CO2 gas is discharged upwards. A drain valve 14 is located at the bottom of the gas-liquid separator 12. Operators can periodically drain the trapped liquid through the drain valve 14 according to the liquid level, effectively preventing excessive liquid accumulation and subsequent mixing into the gas delivery pipeline, thus avoiding liquid hammer or damage to downstream equipment. The high-purity CO2 gas purified and separated by the gas-liquid separator 12 then enters the suction inlet of the CO2 circulation pump 13. Under the continuous mechanical pressurization, the gas is repressurized and transported, and then returned to the air inlet pipe at the bottom of the pulping circulation mineralization tank 15 through the circulating air inlet valve 16. Finally, it diffuses into the slurry through the disc aerator 6. Through the closed-loop circulation process of the pulping circulation mineralization tank 15 (top → circulating air outlet valve 11 → gas-liquid separator 12 → CO2 circulation pump 13 → circulating air inlet valve 16 → disc aerator 6 → pulping circulation mineralization tank 15), unreacted CO2 can be continuously recycled and reused inside the equipment until most of the CO2 in the gas is fully absorbed and mineralized by the slurry. This design greatly extends the effective residence time of CO2 in the slurry, multiplying its mineralization utilization rate, while effectively reducing the fugitive emission of CO2 into the atmosphere, resulting in significant environmental benefits.

[0029] Once the mineralization reaction reaches the preset time point or reaction index, the slurry needs to be transferred out for grouting. At this time, the slurry outlet valve 17 at the lower outlet of the slurry circulation mineralization tank 15 is opened, and the fully mineralized and modified low-carbon sealing slurry enters the buffer anti-settling unit through the pipeline. The core of this unit is the buffer slurry tank 20. An anti-settling agitator 18 is installed inside the buffer slurry tank 20. Since the on-site grouting pump 23 usually pumps continuously, while the slurry discharge process of the slurry circulation mineralization tank 15 is intermittent and carried out in batches, there is a natural mismatch between the two in terms of time scale. The buffer slurry tank 20 plays a key role as a reservoir in this process. Its large volume can temporarily store multiple batches of mineralized slurry, effectively smoothing out peaks and filling valleys, and completely eliminating the adverse effects of the instantaneous flow fluctuation of the slurry discharged from the slurry circulation mineralization tank 15 on the slurry inlet stability of the subsequent grouting pump 23.

[0030] To ensure that the slurry stored in the buffer slurry tank 20 maintains excellent construction performance while waiting for the grouting pump 23 to extract it, the anti-settling agitator 18 operates continuously or intermittently at a low speed, providing slow shear force to the slurry. This effectively disrupts the tendency of solid particles in the slurry to settle due to gravity and separate into layers, preventing the slurry from hardening at the bottom and bleeding at the top. As a further preferred embodiment of the invention, the buffer slurry tank 20 can also be equipped with a slurry return pipeline. This return pipeline can extract the slurry at the bottom of the buffer slurry tank 20 and circulate it back to the top of the tank, or a bypass can be set at the outlet of the grouting pump 23 to allow some slurry to flow back into the buffer slurry tank 20. This dual anti-settling system, combining low-speed anti-settling agitation with pipeline circulation, can maximize the maintenance of a highly uniform pseudoplastic fluid state of the slurry before it enters the grouting pump 23, effectively avoiding grouting pipe blockage accidents caused by slurry stratification and particle agglomeration, and significantly improving the reliability of grouting construction and the quality of hole sealing.

[0031] To ensure the cleanliness and maintenance of the equipment after long-term continuous construction, the buffer slurry tank 20 is specially designed with a cleaning water inlet 19 and a drain valve 21. The cleaning water inlet 19 is located above the side wall or top of the buffer slurry tank 20 and is connected to the on-site high-pressure water source via a hose. After the grouting and sealing operation is completed, high-pressure cleaning water can be introduced into the buffer slurry tank 20 and the grouting pump 23, grouting pipe 24 and related slurry valves connected thereafter through the cleaning water inlet 19 to powerfully flush and dissolve the residual slurry adhering to the tank wall and the inner wall of the pipes. The drain valve 21 is located at the lowest point of the buffer slurry tank 20 and is used to discharge the residual slurry deposits, slurry lumps and cleaning waste liquid flushed down. This complete cleaning and drain structure configuration can effectively prevent the low-carbon sealing slurry with gelling properties from solidifying and hardening during equipment downtime, greatly reducing the risk of pump jamming and pipe blockage caused by residual slurry solidification, and significantly improving the continuous use frequency of the equipment and the convenience of daily maintenance.

[0032] The outlet of the buffer slurry tank 20 is connected to the grouting unit. The core equipment of the grouting unit is the grouting pump 23. The inlet of the grouting pump 23 is connected to the lower outlet of the buffer slurry tank 20. It is used to draw the uniformly stirred mineralized slurry in the tank into the pump chamber and apply high pressure to overcome the friction resistance along the pipeline. The outlet of the grouting pump 23 is connected to the grouting pipe 24. The grouting pipe 24 extends along the borehole direction and finally connects to the sealing section 25 of the pre-constructed gas drainage borehole in the coal seam 26. In actual operation, after the grouting pump 23 is started, it continuously pumps the mineralized slurry in the buffer slurry tank 20 to the sealing section 25 through the grouting pipe 24, so that the slurry is pressurized. Under the action of force, the grout penetrates into the annular gaps, fissures, and broken coal and rock masses around the borehole in the sealing section. After the grout solidifies, it forms a dense and high-strength sealing isolation zone, achieving complete sealing of the gas extraction borehole. In this embodiment, the grouting pump 23 can be selected from plunger pumps, screw pumps, diaphragm pumps, or other pump types suitable for conveying high solids content grout according to the actual working conditions on site. Furthermore, the effective volume, internal structure, and arrangement of the grouting circulation mineralization tank 15 and the buffer grout tank 20 can be flexibly customized and adjusted according to the number of boreholes, the length of the single-hole sealing section, and the total grouting volume required on the coal mine site, demonstrating strong engineering adaptability.

[0033] When using the above-mentioned complete set of equipment for on-site sealing construction, the specific operation process and technological logic are as follows: The first step is construction preparation and equipment inspection. Before formally adding materials, operators must comprehensively inspect all components of the equipment, including but not limited to CO2 cylinder 1, cylinder pressure gauge 2, pressure reducing valve 3, gas mass flow controller 4, air inlet valve 5, pulping and circulating mineralization tank 15, mixing assembly 7, disc aerator 6, circulating air outlet valve 11, gas-liquid separator 12, CO2 circulating pump 13, drain valve 14, circulating air inlet valve 16, slurry outlet valve 17, buffer slurry tank 20, anti-settling agitator 18, grouting pump 23, grouting pipe 24, cleaning water inlet 19, and drain valve 21. Ensure that the air supply pipeline is leak-free, all valves open and close flexibly, the electrical control system is normal, and confirm that all units of the equipment are in good standby working condition.

[0034] The second step is raw material feeding and batching. Cement, fly ash, mineral admixtures, expanding agents, and other functional solid powder raw materials are accurately weighed and added into the tank through the sealed flange feeding port 9 at the top of the pulping and circulating mineralization tank 15. At the same time, the calculated amount of mixing water is added into the tank through the water inlet valve 10. For the sealing requirements under special geological conditions, an appropriate amount of liquid admixture can also be added into the tank through the water inlet valve 10 or an additional liquid feeding interface according to the design ratio to improve the fluidity of the slurry or shorten the setting time.

[0035] The third step is to stir and prepare the slurry. After all the solid and liquid raw materials have entered the tank, the stirring component 7 is started immediately. Under the continuous and high-speed mechanical stirring action of the stirring component 7, the solid powder, mixing water and liquid additives in the tank are fully mixed, wetted and dispersed, and finally a low-carbon sealing slurry with uniform rheological properties is prepared to ensure the homogeneity of the subsequent mineralization reaction.

[0036] The fourth step is initial aeration and mineralization startup. The main valve of CO2 cylinder 1 is opened, and high-pressure CO2 gas flows out, passing through pressure reducing valve 3 for pressure reduction, and gas mass flow controller 4 for precise flow control. Finally, it enters the disc aerator 6 at the bottom of the pulping and circulating mineralization tank 15 through inlet valve 5. The disc aerator 6 converts CO2 into microbubbles and releases them into the slurry inside the tank. Under the continuous agitation of the stirring component 7, these microbubbles rapidly diffuse, initiating the reaction of CO2 with Ca in the slurry. 2+ Mg 2+ The active alkaline components undergo carbonation and mineralization reactions.

[0037] The fifth step is CO2 recycling and closed-loop mineralization. Simultaneously with aeration, the circulating outlet valve 11, CO2 circulating pump 13, and circulating inlet valve 16 are opened. Residual CO2 gas in the upper space of the pulping circulating mineralization tank 15 that has not reacted or been absorbed by the slurry enters the gas-liquid separator 12 through the circulating outlet valve 11 under pressure differential. Inside the gas-liquid separator 12, fine slurry droplets and moisture mixed in the gas are effectively blocked and settled. The separated pure CO2 gas is pressurized and transported by the CO2 circulating pump 13 and returned to the disc aerator 6 at the bottom of the pulping circulating mineralization tank 15 through the circulating inlet valve 16, forming a complete closed-loop cycle. During this cycle, the liquid trapped at the bottom of the gas-liquid separator 12 can be periodically and centrally discharged through the drain valve 14 to maintain the efficient operation of the circulation loop. This step ensures that the CO2 gas is repeatedly utilized within the tank until the reaction reaches saturation.

[0038] Step 6: Slurry transfer and buffering to prevent sedimentation; After the pulping and circulating mineralization reaction reaches the set time target, close the corresponding air supply valve and open the slurry outlet valve 17 at the bottom of the pulping and circulating mineralization tank 15 to transport the mineralized low-carbon sealing slurry to the buffer slurry tank 20 through the pipeline; At the same time, immediately start the anti-settling agitator 18 inside the buffer slurry tank 20 to run it continuously at low speed to ensure that the mineralized slurry does not undergo gravity sedimentation or segregation during the waiting process for the grouting pump 23 to extract it; As a further preferred anti-settling measure, if necessary, a special return pipe can be connected to the buffer slurry tank 20 to form a micro-circulation of the slurry in the tank or the slurry at the outlet of the grouting pump 23 inside the buffer slurry tank 20 to further enhance the anti-settling effect.

[0039] Step 7: Grouting and sealing construction; After the mineralized slurry stabilizes in the buffer slurry tank 20, start the grouting pump 23; The grouting pump 23 extracts the mineralized slurry, which has always been kept in a uniform state in the buffer slurry tank 20, and applies high pressure for transportation; The slurry is continuously injected into the pre-arranged sealing section 25 of the coal seam 26 through the grouting pipe 24; As the grouting pressure increases, the slurry penetrates and fills the fissure space of the sealing section 25 and the surrounding coal and rock mass under the action of pressure, so as to achieve a tight seal on the periphery of the gas drainage borehole, and then the grouting pump is stopped.

[0040] Step 8: Post-construction equipment cleaning and maintenance; After all grouting and sealing are completed, sequentially close the grouting pump 23, grout outlet valve 17, air inlet valve 5, circulating air inlet valve 16, and circulating air outlet valve 11, and stop the operation of the CO2 circulating pump 13 and the anti-settling agitator 18; Subsequently, use the on-site water source to connect to the cleaning water inlet 19, and forcefully flush the buffer grout tank 20, grouting pump 23, and grouting pipe 24 with a large amount of clean water to thoroughly remove the grout remaining inside each component; The wastewater after flushing and the sediment deposited at the bottom of the buffer grout tank 20 are discharged through the drain valve 21 to prevent the residual grout from hardening and caking, which could cause blockages in the equipment and pipelines, and to make full preparations for the next construction.

[0041] This invention integrates the on-site preparation of low-carbon sealing slurry, closed-loop CO2 mineralization modification, slurry buffering and anti-settling, and final borehole grouting and sealing into one unit, exhibiting extremely high integrity and originality in equipment structure and process flow. The core technical details described in this specific embodiment, such as the sealed structure of the slurry circulating mineralization tank, the synergistic reaction mechanism of the disc aerator and stirring components, the CO2 closed-loop circulation loop involving the gas-liquid separator, and the low-speed stirring anti-settling and cleaning and sewage discharge mechanism in the buffer tank, are not only applicable to the sealing engineering of underground gas extraction boreholes in coal mines, but also widely applicable to various low-carbon cementitious material construction application scenarios that require on-site immediate preparation, CO2-enhanced mineralization modification, and continuous grouting.

[0042] 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.

[0043] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A carbon dioxide circulating mineralization grouting equipment for sealing gas extraction boreholes, characterized in that, It includes an air supply unit, a pulping and circulating mineralization unit, a buffer and anti-settlement unit, and a grouting unit; The gas supply unit, pulping and circulating mineralization unit, buffer and anti-settling unit and grouting unit are all integrated on the skid-mounted platform (22); The gas supply unit is used to supply carbon dioxide gas to the pulping and circulating mineralization unit; The pulping and circulating mineralization unit includes a pulping and circulating mineralization tank (15), which is used to mix solid raw materials with mixing water to prepare low-carbon sealing slurry, and to use the carbon dioxide gas to carry out circulating mineralization modification of the low-carbon sealing slurry. The buffer anti-settling unit includes a buffer slurry tank (20), which is connected to the pulping and circulating mineralization unit and is used to temporarily store the mineralized slurry and maintain the uniform dispersion of the slurry before injection. The grouting unit includes a grouting pump (23), which is connected to the buffer anti-settlement unit and is used to pressurize and transport the grout in the buffer anti-settlement unit to the sealing section (25) of the coal seam (26).

2. The carbon dioxide circulating mineralization grouting equipment for gas extraction sealing as described in claim 1, characterized in that, The pulping and circulating mineralization unit also includes a sealed flange feeding port (9), a water inlet valve (10), a mechanical seal (8), a stirring assembly (7), a disc aerator (6), a circulating air outlet valve (11), a gas-liquid separator (12), a CO2 circulating pump (13), a drain valve (14), a circulating air inlet valve (16), and a slurry outlet valve (17). The sealed flange feeding port (9) and water inlet valve (10) are installed on the pulping and circulating mineralization tank (15) and are used to add solid raw materials, mixing water and liquid additives, respectively. The stirring assembly (7) is disposed inside the pulping and circulating mineralization tank (15), and the mechanical seal (8) is provided at the part of the stirring assembly (7) that passes through the pulping and circulating mineralization tank (15); The disc aerator (6) is located at the bottom of the pulping and circulating mineralization tank (15) and is connected to the air supply unit; The upper exhaust port of the pulping and circulating mineralization tank (15) is connected to the gas-liquid separator (12) through the circulating air valve (11). The liquid outlet of the gas-liquid separator (12) is provided with the drain valve (14), and the gas outlet is connected to the CO2 circulating pump (13). The CO2 circulating pump (13) is connected to the disc aerator (6) through the circulating air inlet valve (16) to form a gas circulation loop. The slurry outlet valve (17) is located at the bottom slurry outlet of the pulping circulation mineralization tank (15).

3. The carbon dioxide circulating mineralization grouting equipment for gas extraction sealing according to claim 2, characterized in that, The gas-liquid separator (12) is used to separate liquid droplets or slurry mist droplets entrained in the circulating gas. The separated liquid is discharged through the drain valve (14), and the separated carbon dioxide gas is transported through the CO2 circulating pump (13) and returned to the disc aerator (6) via the circulating air inlet valve (16).

4. The carbon dioxide circulating mineralization grouting equipment for gas extraction sealing as described in claim 1, characterized in that, The buffer anti-settling unit also includes an anti-settling agitator (18); The anti-settling agitator (18) is installed inside the buffer slurry tank (20) and is used to slow down or prevent the sedimentation and segregation of the slurry in the buffer slurry tank (20) by low-speed agitation.

5. The carbon dioxide circulating mineralization grouting equipment for gas extraction sealing according to claim 4, characterized in that, The buffer slurry tank (20) is also equipped with a cleaning water inlet (19) and a drain valve (21); The cleaning water inlet (19) is used to introduce cleaning medium into the passage of the buffer slurry tank (20) and the grouting unit; The drain valve (21) is used to drain the sediment, residual slurry or cleaning waste liquid at the bottom of the buffer slurry tank (20).

6. The carbon dioxide circulating mineralization grouting equipment for gas extraction sealing according to claim 1, characterized in that, The grouting unit also includes a grouting pipe (24); The outlet of the grouting pump (23) is connected to the grouting pipe (24), and the grouting pipe (24) is connected to the sealing section (25) in the coal seam (26).

7. The carbon dioxide circulating mineralization grouting equipment for gas extraction sealing according to claim 1, characterized in that, The gas supply unit includes a CO2 cylinder (1), a cylinder pressure gauge (2), a pressure reducing valve (3), a gas mass flow controller (4), and an inlet valve (5); The outlet of the CO2 cylinder (1) is connected in sequence to the cylinder pressure gauge (2), pressure reducing valve (3), gas mass flow controller (4) and inlet valve (5); The air outlet of the air inlet valve (5) is connected to the air inlet of the pulping and circulating mineralization unit.

8. A method for carbon dioxide circulating mineralization grouting using the equipment described in any one of claims 1 to 7, characterized in that, Includes the following steps: Step S1: After confirming that the equipment is in normal working condition, add solid raw materials into the pulping and circulating mineralization tank (15) through the sealed flange feeding port (9), and add mixing water and liquid additives through the water inlet valve (10); Step S2: Start the stirring assembly (7) to stir the material in the pulping and circulating mineralization tank (15) to prepare a uniform low-carbon sealing slurry; Step S3: Open the CO2 cylinder (1) so that the CO2 gas passes through the pressure reducing valve (3), the gas mass flow controller (4) and the air inlet valve (5) in sequence and enters the disc aerator (6) to disperse into the slurry for mineralization reaction; Step S4: Open the circulating air outlet valve (11), CO2 circulating pump (13) and circulating air inlet valve (16) so that the unreacted CO2 in the upper part of the pulping circulating mineralization tank (15) is separated by the gas-liquid separator (12) and then sent back to the disc aerator (6) by the CO2 circulating pump (13) to realize CO2 circulating mineralization. Step S5: After the mineralization reaction is completed, open the slurry outlet valve (17) to allow the mineralized slurry to enter the buffer slurry tank (20), and start the anti-settling agitator (18) to maintain the uniform dispersion of the slurry. Step S6: Start the grouting pump (23) and transport the mineralized grout in the buffer grout tank (20) to the sealing section (25) of the coal seam (26) through the grouting pipe (24) to complete the grouting and sealing construction.

9. The carbon dioxide circulating mineralization grouting method according to claim 8, characterized in that, In step S4, the circulating gas is separated into gas and liquid by the gas-liquid separator (12), and the trapped liquid is discharged by the drain valve (14).

10. The carbon dioxide circulating mineralization grouting method according to claim 8, characterized in that, After step S6 is completed, cleaning water is introduced into the buffer slurry tank (20) and the grouting pipeline through the cleaning water inlet (19), and residual slurry or cleaning waste liquid is discharged through the drain valve (21); and / or, In step S5, the slurry is stirred at low speed by an anti-settling agitator (18), or a return pipe is set in the buffer slurry tank (20) to circulate the slurry back to maintain the uniformity of the slurry.

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