Carbon dioxide overburden rock isolation grouting filling device and use method thereof

Abstract

The present application relates to the technical field of green mining, and particularly relates to a carbon dioxide overburden isolation grouting filling device and a use method thereof, which integrates a mechanical pretreatment unit, a semi-dry greenhouse gas mineralization reaction chamber, an in-situ high-shear slurry preparation system and a pipe network variable frequency pumping base. After material crushing and activation, a short-distance gas-liquid-solid mass transfer and micro-membrane carbonation precipitation reaction is continuously carried out between the material and high-concentration carbon dioxide in a semi-dry environment with a temperature of 40-60 DEG C and a relative humidity of 60-80%. Then, the slurry prepared by high-strength water mixing is directly pressed into the target stratum separation zone. The present process completely abandons the traditional dry method with extremely high energy consumption, and avoids the wet method problems of high water consumption and heavy metal wastewater from the source. A large amount of in-situ newly generated carbonates in the product greatly increase the support strength of the grouting solidified body through micro-expansion compaction and chemical skeleton effect, and realize the bidirectional cooperation and economic empowerment of carbon emission reduction and mine subsidence prevention and soil protection engineering system.

Description

Technical Field

[0001] This invention relates to the field of green mining technology, and in particular to a carbon dioxide overburden grouting and filling device and its usage method. Background Technology

[0002] Existing solid waste mineralization and carbonation technologies mainly suffer from the following bottlenecks: direct dry processes require high temperature and pressure, resulting in extremely high energy consumption; direct wet processes consume large amounts of water and are prone to wastewater treatment problems; indirect processes require the introduction of chemical solvents, making the process complex and uneconomical. Although semi-dry carbon sequestration processes can be carried out under mild relative humidity, significantly reducing water consumption, there is currently a lack of continuous engineering equipment to integrate them with large-scale resource disposal facilities.

[0003] In the coal mining sector, overburden isolation grouting and backfilling technology is commonly used to control strata movement and surface subsidence. Currently, the grouting materials are mainly water and ordinary fly ash or coal gangue. However, traditional backfilling materials only provide physical filling and lack cementing activity, resulting in limited mechanical properties of the consolidated body, making it prone to compression deformation under overburden pressure. Furthermore, existing coal mine backfilling technologies lack active carbon sequestration capabilities and are not effectively integrated with carbon emission reduction requirements.

[0004] Currently, carbon dioxide sequestration and mine subsidence prevention grouting are separate in terms of equipment and technology. How to design an integrated device that can continuously complete solid waste pretreatment, semi-dry and gentle carbon sequestration, grout preparation and pumping, and achieve coordinated operation, is a technical problem that needs to be solved in this field. Summary of the Invention

[0005] In order to overcome the shortcomings of existing dry carbon fixation methods, such as high energy consumption and excessive wastewater, as well as the low strength and lack of additional carbon emission reduction benefits of traditional mine overburden backfill materials, this invention provides a carbon dioxide overburden isolation grouting backfill device and its usage method that efficiently couples in-situ mild carbon fixation with mine backfill.

[0006] A carbon dioxide overburden isolation grouting and filling device includes a support platform, characterized in that: a crushing unit for material pretreatment, a reaction unit for semi-dry carbon fixation reaction, a slurry preparation unit, and a bucket elevator for material lifting are fixedly connected to the top of the support platform; the crushing unit includes a jaw crusher and a ball mill connected in sequence for progressively crushing and grinding fly ash; the reaction unit includes a reaction chamber fixed to the top of the support platform, the inside of which is equipped with a material turning mechanism and a microporous aeration disc, and a temperature sensor and a pressure gauge are installed on the top of the reaction chamber, the reaction chamber being used to react the crushed fly ash with carbon dioxide under controllable temperature and humidity conditions. The semi-dry mineralization reaction is described. The slurry preparation unit includes a slurry preparation vessel fixed to the top of the support platform. The slurry preparation vessel is located directly below the reaction chamber and is sealed by a discharge port. An agitator is installed inside the slurry preparation vessel, and a water inlet pipe is connected to the side wall or top of the slurry preparation vessel to mix the solidified products after the reaction with water to prepare grouting slurry. The feed port of the bucket elevator is connected to the discharge port of the ball mill, and the discharge port of the bucket elevator is connected to the feed port of the reaction chamber to transport the ground fly ash to the reaction chamber in a completely sealed manner. A base is set at the bottom of the support platform, and a screw pump is fixedly connected to the inside of the base. The inlet of the screw pump is connected to the discharge port of the slurry preparation vessel to pressurize and pump out the prepared grouting slurry.

[0007] Furthermore, in order to better realize the present invention, a heating coil or heating jacket for precise temperature control is provided inside the side wall of the reaction chamber, and a steam inlet pipe is connected to the outside of the reaction chamber for introducing steam into the chamber during the reaction process to adjust the relative humidity.

[0008] Furthermore, in order to better realize the present invention, the crushing unit also includes a feeding bin for temporarily storing materials. The jaw crusher is fixed to the outside of the support platform by a support arm, and the feeding port of the jaw crusher is correspondingly connected to the feeding bin.

[0009] Furthermore, in order to better realize the present invention, a microporous aeration disc is set at the bottom of the reaction chamber and connected to an external carbon dioxide gas source and a flow controller, for uniformly introducing carbon dioxide gas into the reaction chamber at a set constant rate.

[0010] Furthermore, in order to better realize the present invention, the agitator inside the pulping kettle is a vertical shaft paddle mixer, the water inlet pipe is equipped with a regulating valve and a flow meter, and the screw pump adopts a variable frequency drive motor.

[0011] A method for carbon dioxide overburden isolation grouting and backfilling using the above-mentioned device includes the following steps: S1. Raw material pretreatment: fly ash is coarsely crushed by a jaw crusher and finely ground by a ball mill in sequence to increase the specific surface area of ​​fly ash and destroy its surface passivation layer. S2, semi-dry carbon fixation reaction: The ground fly ash is sent into the reaction chamber by a bucket elevator. The temperature of the core reaction zone inside the reaction chamber is controlled at 40-60℃ and the relative humidity is 60-80%. Carbon dioxide is continuously introduced through microporous aeration discs. At the same time, the material turning machine is started to make the fly ash material and carbon dioxide fully contact each other in the semi-dry state and undergo mineralization reaction. After the reaction is completed, the material is left to stand to solidify. S3. Slurry preparation: The solidified material is discharged into the slurry preparation kettle through the discharge port, and water is added through the water inlet pipe according to the set water-solid ratio. The mixer is started to mix evenly to obtain a high-concentration grouting slurry. S4. Downhole filling: Start the screw pump and inject the prepared grout into the underground overburden separation space through the surface pipeline network from the surface grouting borehole, simultaneously achieving physical filling and support of the overburden and geological sequestration of carbon dioxide.

[0012] Furthermore, in order to better realize the present invention, in S1, the proportion of particles with a particle size of less than 0.2 mm in the pretreated fly ash particles is not less than 80%, and the maximum particle diameter is less than 4 mm.

[0013] Furthermore, in order to better realize the present invention, in S2, the carbon dioxide introduction rate is controlled to be 1 L / min to 1.2 L / min. In the initial stage of the reaction when carbon dioxide is introduced, an appropriate amount of water vapor is simultaneously introduced into the reaction chamber to maintain the set relative humidity range.

[0014] Furthermore, in order to better realize the present invention, in S2, the continuous reaction time of fly ash and carbon dioxide gas is 6 to 8 hours, the static solidification time is controlled at 6 hours, and the operating speed of the material turning machine is maintained at 30-50 rpm during the reaction.

[0015] Furthermore, in order to better realize the present invention, in S3, the water-to-solid ratio is controlled within the range of 0.8:1 to 1.2:1, and the density of the prepared grouting slurry is controlled between 1.1t / m³ and 1.5t / m³; in S4, the fly ash is an industrial alkaline solid waste containing calcium oxide and magnesium oxide components, including coal gangue.

[0016] The beneficial effects of this invention are: 1. The crushing, lifting, semi-dry carbon fixation reaction, pulping and pumping processes are integrated into a compact device. This integrated design greatly reduces material transfer links and site occupation, and improves the system's automation level and operating efficiency.

[0017] 2. The semi-dry process employed is carried out under mild conditions of 40-60℃ and 60-80% humidity, with reaction efficiency ensured through microporous aeration and mechanical agitation. This method consumes significantly less energy than dry and wet methods, and the carbonates generated by the CO2 mineralization reaction provide additional cementing and reinforcing effects to the filling material. Experiments show that the strength of the filling material prepared in this way can be increased by more than 100% compared to traditional fly ash slurry, achieving a synergistic effect of carbon fixation and reinforcement.

[0018] 3. Using fly ash and other solid wastes as the main raw materials and CO2 as the reactant, the system achieves synergistic resource utilization of both types of waste. The entire process requires no expensive chemicals and produces no toxic wastewater, making it environmentally friendly. The mild reaction conditions reduce the pressure and temperature resistance requirements of the equipment, and its core device structure is relatively simple, with controllable construction and operating costs, making it easy to promote in mining areas.

[0019] 4. The screw pump delivery system at the end of the device is fully compatible with existing mine surface drilling and grouting processes, facilitating technology integration and engineering implementation. Through this technology, mines can not only manage goaf areas and protect surface ecology, but also directly contribute to carbon emission reduction, providing a feasible and practical new approach for the green transformation of mining areas. Attached Figure Description

[0020] Figure 1 This is a front view of the system structure of the carbon dioxide overburden isolation grouting and filling device provided in an embodiment of the present invention; Figure 2 The left view of the system structure of the carbon dioxide overburden isolation grouting and filling device provided in the embodiment of the present invention; Figure 3 This is a rear view of the system structure of the carbon dioxide overburden isolation grouting and filling device provided in an embodiment of the present invention; Figure 4 This is a partial structural diagram of a high-pressure variable frequency screw pump located at the base, provided in an embodiment of the present invention.

[0021] In the picture, 1. Support platform; 2. Feeding hopper; 3. Support arm; 4. Jaw crusher; 5. Ball mill; 6. Bucket elevator; 7. Reaction chamber; 8. Pulping kettle; 9. Base; 10. Screw pump; 11. Material turning machine; 12. Mixer; 13. Water inlet pipe; 14. Microporous aeration disc; 15. Temperature sensor; 16. Pressure gauge. Detailed Implementation

[0022] 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 a part of the embodiments of the present invention, and not all of them. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0023] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0024] Reference Figures 1 to 4 This embodiment provides a carbon dioxide overburden isolation grouting and filling device, including a support platform 1, with a base 9 connected to the bottom of the support platform 1. The device includes the following parts: (a) Physical preprocessing unit This unit includes a feeding hopper 2, a jaw crusher 4, and a ball mill 5. The outlet of the feeding hopper 2 corresponds to the receiving port of the jaw crusher 4. The jaw crusher 4 is fixed to the outside of the support platform 1 by a support arm 3. The jaw crusher 4 performs coarse crushing on the material, which then enters the ball mill 5 fixed on the support platform 1 for fine grinding.

[0025] (ii) Material conveying unit The conveying system uses a closed bucket elevator 6. The bottom inlet of the bucket elevator 6 is connected to the discharge end of the ball mill 5, and the top outlet is connected to the inlet of the reaction chamber 7.

[0026] (III) Semi-dry carbon fixation reaction unit The main reaction equipment is a sealed reaction chamber 7 fixed to the top of the support platform 1. Heating coils or heating jackets are installed inside the side walls of the reaction chamber 7, connected to temperature sensors 15 extending into the chamber. A steam inlet pipeline is connected to the outside of the reaction chamber 7. A microporous aeration disc 14 is installed at the bottom of the reaction chamber 7, which is connected to an external carbon dioxide storage tank and a flow controller. A material turning mechanism 11 is installed at the central axis of the reaction chamber 7. A pressure gauge 16 is mounted on the top of the reaction chamber 7.

[0027] (iv) Pulping Unit The pulping vessel 8 is located directly below the reaction chamber 7, and the bottom discharge port of the reaction chamber 7 is directly connected to the pulping vessel 8. A vertical shaft paddle mixer 12 is installed inside the pulping vessel 8. A water inlet pipe 13 is connected to the upper side of the pulping vessel 8, and a flow meter is installed on the water inlet pipe 13.

[0028] (v) Pumping unit The discharge pipe at the bottom of the pulping vessel 8 is connected to the screw pump 10, which is fixedly installed inside the base 9. The screw pump 10 is driven by a frequency converter.

[0029] The specific working steps of the above-mentioned device are as follows: S1. Raw material pretreatment: Solid waste materials such as fly ash are fed into jaw crusher 4 for coarse crushing, and then into ball mill 5 for grinding to increase their specific surface area.

[0030] S2. Semi-dry carbonization reaction: The ground material is transferred to the reaction chamber 7 via a bucket elevator 6. The temperature inside the reaction chamber 7 is regulated and controlled at 40-60℃ by a heating coil; a suitable amount of water vapor is injected through the steam inlet pipe to maintain the relative humidity inside the chamber at 60-80%. CO2 gas is introduced into the microporous aeration disc 14 at a rate of 1.2L / min, while the material turning machine 11 is started and runs at a speed of 30-50 rpm. The main reaction time is 6-8 hours. After the reaction is completed, the aeration disc and turning machine are turned off, and the material is left to stand for 6 hours to complete the solidification.

[0031] S3. Slurry preparation: The material that has completed the curing reaction is discharged into the lower slurry preparation tank 8. Water is injected through the water inlet pipe 13 at a water-to-solid ratio of 0.8:1 to 1.2:1. The mixer 12 is started to mix and stir the material evenly, preparing a suspension grouting slurry with a density of 1.1t / m³ to 1.5t / m³.

[0032] S4. Downhole filling: Start screw pump 10 to pump the prepared grout into the high-pressure seamless pipeline network, and inject it into the abscission space of the underground overburden through surface boreholes.

[0033] To verify the effectiveness of the present invention, a comparative experiment was conducted: Carbon fixation efficiency: Thermogravimetric-differential scanning calorimetry (TGC-DSC) analysis was performed on the solidified product after treatment using the method described in this embodiment. The results showed that the carbonate content in the product was significantly increased compared to the original fly ash, with a carbon fixation efficiency of 85-100 kg CO2 / ton of fly ash, demonstrating the effective carbon fixation capability of the semi-dry method under mild conditions.

[0034] Infill material performance: The slurry prepared by this method was cast into standard test blocks, and its uniaxial compressive strength was tested after curing for 28 days. The results showed that its strength reached 3.0-3.5 MPa, which is about 1.5 MPa compared with ordinary fly ash slurry of the same water-to-solid ratio without CO2 mineralization treatment, representing a strength increase of more than 100%. This is due to the additional cementing and reinforcing effect of carbonate formation.

[0035] Energy consumption and environmental friendliness: The core reaction temperature of this process is only around 50℃, far lower than that of the dry process (>300℃), and it does not require heating a large amount of water as in the wet process, reducing energy consumption by more than 60%. There is no wastewater discharge throughout the entire process, achieving the synergistic resource utilization of CO2 and solid waste.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention, as long as they do not depart from the spirit and scope of the technical solutions of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A carbon dioxide overburden isolation grouting and filling device, comprising a support platform (1), characterized in that: The top of the support platform (1) is fixedly connected to a crushing unit for material pretreatment, a reaction unit for semi-dry carbon fixation reaction, a slurry preparation unit for slurry preparation, and a bucket elevator (6) for material lifting. The crushing unit includes a jaw crusher (4) and a ball mill (5) connected in sequence, used to crush and grind fly ash step by step; The reaction unit includes a reaction chamber (7) fixed to the top of the support platform (1). The reaction chamber (7) is equipped with a material turning machine (11) and a microporous aeration disc (14). The top of the reaction chamber (7) is equipped with a temperature sensor (15) and a pressure gauge (16). The reaction chamber (7) is used to make the crushed fly ash react with carbon dioxide in a semi-dry mineralization reaction under controllable temperature and humidity conditions. The pulping unit includes a pulping vessel (8) fixed to the top of the support platform (1). The pulping vessel (8) is located directly below the reaction chamber (7) and is sealed by the discharge port. A mixer (12) is installed inside the pulping vessel (8). A water inlet pipe (13) is connected to the side wall or top of the pulping vessel (8) for mixing the solidified product after reaction with water to prepare grouting slurry. The feed inlet of the bucket elevator (6) is connected to the discharge outlet of the ball mill (5), and the discharge outlet of the bucket elevator (6) is connected to the feed inlet of the reaction chamber (7), which is used to transport the ground fly ash to the reaction chamber (7) in a completely sealed manner; a base (9) is provided at the bottom of the support platform (1), and a screw pump (10) is fixedly connected to the inner side of the base (9). The inlet of the screw pump (10) is connected to the discharge outlet of the slurry preparation kettle (8), which is used to pressurize and pump out the prepared grouting slurry.

2. The carbon dioxide overburden isolation grouting and filling device according to claim 1, characterized in that: The reaction chamber (7) is equipped with a heating coil or heating jacket for precise temperature control inside the side wall. The reaction chamber (7) is connected to a steam inlet pipe to introduce steam into the chamber during the reaction process to adjust the relative humidity.

3. The carbon dioxide overburden isolation grouting and filling device according to claim 1, characterized in that: The crushing unit also includes a feeding bin (2) for temporary storage of materials. The jaw crusher (4) is fixed to the outside of the support platform (1) by a support arm (3). The feeding port of the jaw crusher (4) is connected to the feeding bin (2).

4. The carbon dioxide overburden isolation grouting and filling device according to claim 1, characterized in that: The microporous aeration disc (14) is located at the bottom of the reaction chamber (7) and connected to an external carbon dioxide gas source and flow controller, for uniformly introducing carbon dioxide gas into the reaction chamber (7) at a set constant rate.

5. The carbon dioxide overburden isolation grouting and filling device according to claim 1, characterized in that: The mixer (12) inside the pulping vessel (8) is a vertical shaft paddle mixer. The water inlet pipe (13) is equipped with a regulating valve and a flow meter. The screw pump (10) is driven by a variable frequency motor.

6. A method for carbon dioxide overburden isolation grouting and filling using the carbon dioxide overburden isolation grouting and filling device as described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Raw material pretreatment: fly ash is coarsely crushed by jaw crusher (4) and finely ground by ball mill (5) in sequence to increase the specific surface area of ​​fly ash and destroy its surface passivation layer. S2, Semi-dry carbon fixation reaction: The ground fly ash is sent into the reaction chamber (7) by the bucket elevator (6). The temperature of the core reaction zone inside the reaction chamber (7) is controlled at 40-60℃ and the relative humidity is 60-80%. Carbon dioxide is continuously introduced through the microporous aeration disc (14). At the same time, the material turning machine (11) is started so that the fly ash material and carbon dioxide can fully contact each other in the semi-dry state and undergo mineralization reaction. After the reaction is completed, the material is left to stand to solidify. S3. Slurry preparation: The solidified material is discharged into the slurry preparation vessel (8) through the discharge port, and water is added through the water inlet pipe (13) according to the set water-solid ratio. The mixer (12) is started to mix evenly to obtain high-concentration grouting slurry. S4. Downhole filling: Start the screw pump (10) to inject the prepared grout into the underground overburden separation space through the ground pipeline network from the ground grouting borehole, so as to simultaneously realize the physical filling and support of the overburden and the geological sealing of carbon dioxide.

7. The carbon dioxide overburden isolation grouting filling method according to claim 6, characterized in that: In S1, after pretreatment, the proportion of particles with a diameter less than 0.2 mm is not less than 80%, and the maximum particle diameter is less than 4 mm.

8. The carbon dioxide overburden isolation grouting filling method according to claim 6, characterized in that: In S2, the carbon dioxide introduction rate is controlled to be 1 L / min to 1.2 L / min. In the initial stage of the reaction with carbon dioxide, an appropriate amount of water vapor is simultaneously introduced into the reaction chamber (7) to maintain the set relative humidity range.

9. The carbon dioxide overburden isolation grouting filling method according to claim 6, characterized in that: In S2, the continuous reaction time of fly ash and carbon dioxide gas is 6 to 8 hours, the static solidification time is controlled to be 6 hours, and the operating speed of the material turning machine (11) is maintained at 30-50 rpm during the reaction.

10. The carbon dioxide overburden isolation grouting filling method according to claim 6, characterized in that: In step S3, the water-to-solid ratio is controlled within the range of 0.8:1 to 1.2:1, and the density of the prepared grout is controlled between 1.1 t / m³ and 1.5 t / m³. In step S4, the fly ash is an industrial alkaline solid waste containing calcium oxide and magnesium oxide components, including coal gangue.

Images