Mining damage control method for multi-medium carbon pollution cooperative reduction and control and resource application

Abstract

The invention relates to a mining damage control method for multi-medium carbon pollution cooperative reduction and control and resource application, and belongs to the technical field of full-waste resource treatment and utilization of a short-distance coal seam mining goaf. The mining damage control method comprises the following steps that filling liquid and filling materials are stirred and mixed while carbon dioxide gas is introduced to form filling slurry; then all-directional shower type spraying is conducted from the filling pipeline to the goaf; performing full grouting on the goaf in a sealed form until the goaf is full, introducing carbon dioxide into the goaf while performing full grouting, monitoring and analyzing underground behaviors, rock reaction and rock stratum stability of carbon dioxide in a backfilling area, and when underground water exists in a sealing and storing area, establishing an underground water monitoring system to monitor the water quality of the underground water; the power plant flue gas is treated and then injected into the goaf to be mixed with the filling material, so that the oxygen concentration of the goaf is effectively reduced, goaf fire disasters are prevented and treated, mining disasters in the goaf are effectively controlled, and the stability of rock strata is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of total waste resource disposal and utilization in goaf areas of close-range coal seam mining, and specifically refers to a mining damage control method with coordinated reduction and control of multi-media carbon pollution and resource application. Background Art

[0002] In the process of mining and use, the coal industry has become a key factor hindering its sustainable development and green and healthy development due to the discharge of high-salt mine water, the accumulation of a large amount of solid waste, the formation of goafs, and a large amount of carbon dioxide emissions. Goaf mining disasters and rock migration are the second main challenges faced in the process of coal mining. Goaf fire control has always been an important challenge in the field of mining engineering. In the underground mining process, goafs are buried with rich coal resources, but there are also potential fire risks. Fires not only threaten the lives of miners, but may also cause damage to mining equipment, production interruptions, and environmental pollution. Therefore, the prevention and control of goaf fires is crucial. Mining disasters may cause the destruction of goaf structures, cause rock formations to move, increase the work risks of miners, and may cause accidents. In addition, rock migration may also cause changes in groundwater levels, which will have an adverse impact on coal mining work and the environment. Therefore, the control of mining disasters and the stability of rock migration are crucial to ensure the safety of mining work and environmental protection.

[0003] At the same time, carbon dioxide in flue gas emissions from power plants has become one of the main sources of environmental problems. Carbon dioxide is a greenhouse gas, and its emissions have an adverse impact on the global climate. Therefore, reducing the concentration of carbon dioxide in flue gas emissions from power plants, carrying out the storage and utilization of carbon dioxide, and reducing carbon emissions have become one of the important tasks in the field of environmental protection. In addition, mine water contains a large amount of corrosive ions, which corrode the filling materials and reduce their mechanical properties. How to solve the sewage treatment generated in the development and utilization of coal resources, enhance the filling body resistant to mine water corrosion, and the accumulation of large coal-based solid wastes such as gangue and fly ash is also imminent.

[0004] However, the current problem is the lack of a comprehensive technical approach that can simultaneously address the triple challenges of mining disaster control, rock migration stability, and carbon emission reduction. In particular, in the water-gas-solid synergistic utilization of sewage, power plant flue gas, and solid waste materials in goafs, current technologies and methods are still insufficient. This problem hinders the realization of the goals of sustainable development and environmental protection of the coal mining industry. Therefore, there is an urgent need for an innovative approach that can comprehensively address these challenges and ensure the safety and environmental protection of goafs. Summary of the invention

[0005] In order to overcome some of the problems mentioned in the above background, the present invention provides a mining damage control method for coordinated reduction and resource application of multi-media carbon pollution, which at least partially solves the above problems.

[0006] According to the technical solution of the present invention, a mining damage control method for multi-media carbon pollution coordinated reduction and control and resource utilization is provided, comprising the following steps:

[0007] The filling liquid and the filling material are stirred and mixed while carbon dioxide gas is introduced to form a filling slurry;

[0008] Then, the filling pipe is sprayed in an all-round shower-like manner to the goaf, and the side walls, roof and floor surfaces of the goaf are fully sealed;

[0009] The sealed goaf is fully grouted until it fills the goaf. Carbon dioxide is introduced into the goaf during the full grouting. The injection rate and pressure of the filling slurry and carbon dioxide into the goaf are controlled to maintain the carbon dioxide mineralization rate and low oxygen concentration in the goaf.

[0010] Monitor and analyze the underground behavior, rock reaction and rock formation stability of carbon dioxide in the backfill area. When there is groundwater in the storage area, establish a groundwater monitoring system to monitor the water quality of the groundwater;

[0011] The filling liquid includes alkaline silicon-based activator and mine wastewater, and the filling material includes coal-based solid waste and salt-resistant corrosion agent.

[0012] Furthermore, the temperature of the carbon dioxide introduced into the goaf is 27-32° C. and the pressure is 1 MPa-6 MPa.

[0013] Furthermore, the total amount M of carbon dioxide injected into the goaf is calculated by the following formula:

[0014] M=Qt×ρ C +(V-V')k

[0015] Where M is the total amount of carbon dioxide injected into the goaf; V is the volume of the goaf to be filled obtained from geological survey or underground exploration, V' is the volume of carbon dioxide injected, Q is the volume flow rate of injected carbon dioxide, and t is the injection time; ρ C is the density of carbon dioxide and k is the safety factor.

[0016] Furthermore, the required injection amount of the filling slurry is calculated by the following formula:

[0017] V 注 =VW 浆 ρ 浆

[0018] Where V is the volume of the goaf; W浆 Indicates the percentage of solid filling material in the filling slurry; ρslurry indicates the density of the filling slurry, where W 浆 It is 45%-85%.

[0019] Furthermore, in order to ensure the stability of the rock formation and the mineralization rate of coal-based solid waste, the minimum injection pressure of carbon dioxide P is determined according to the depth of the goaf and the characteristics of the rock formation. min for:

[0020] P min =P 地表 +ρgh

[0021] Where: P min is the minimum injection pressure; Psurface is the surface atmospheric pressure; ρ is the rock density; g is the standard gravitational acceleration; h is the depth of the goaf.

[0022] Furthermore, the filling slurry has a viscosity of 450 to 1000 mPa.s, a pH value of 8 to 12, a solidification time of 50 to 800 min, and a carbon fixation rate of 5.6 to 35.8 mgCO. 2 / g; after filling, the initial compressive strength without corrosion is greater than 1.4MPa, the compressive strength after corrosion is greater than 1.3MPa, and the strength corrosion resistance rate is about 91%.

[0023] Furthermore, detailed geological surveys are also required:

[0024] Explore information on geological landforms, lithology, structural faults, stratum inclination, etc. to ensure that there are no obvious geological defects in the area. Use rangefinders and underground exploration equipment to measure the spatial size and shape of the goaf, obtain the length, width and height information of the goaf, select appropriate injection points, and ensure safe sealing and filling.

[0025] Furthermore, the carbon dioxide is obtained by purifying and capturing flue gas from a power plant, specifically:

[0026] The flue gas from the power plant is first passed through purification equipment to remove solid particles, sulfur compounds, nitrogen oxides and other harmful substances. Appropriate ventilation ducts and connecting devices are installed to guide the flue gas from the power plant to the capture equipment to enrich carbon dioxide. Before and after the capture equipment, the flue gas characteristics are tested and analyzed, and the carbon dioxide concentration, temperature, pressure and other parameters in the flue gas are tested.

[0027] Furthermore, before the flue gas from the power plant enters the capture equipment, a gas flow meter is installed to measure the volume flow of the flue gas, and this value is recorded and marked as Q. The temperature of the conveyed flue gas is lower than 31°C, and the pressure is controlled at 1-6MPa.

[0028] Furthermore, the filling material includes the following materials in percentage by mass:

[0029] 15% to 26% of coal gangue, 5% to 10% of blast furnace slag, 35% to 49% of fly ash, 16% to 24% of desulfurized gypsum, 10% to 17% of gasified slag, 9% to 18% of bottom ash, and 0.5% to 2% of salt-resistant corrosion agent;

[0030] The preparation method of the filling material is: respectively add coal gangue, blast furnace slag, fly ash, desulfurized gypsum, gasified slag, bottom slag, and salt-resistant corrosion agent into a ball mill for ball milling for 30 to 60 minutes, and continuously stir the mixed powder after ball milling with the filling liquid for 5 to 20 minutes at a stirring rate of 1000 to 10000 r / min.

[0031] Compared with the prior art, the beneficial effects of the present invention are:

[0032] (1) The present invention injects the treated flue gas from the power plant into the goaf and mixes it with the filling material, thereby effectively reducing the oxygen concentration in the goaf, preventing and controlling fires in the goaf, and effectively controlling mining disasters in the goaf, thereby increasing the stability of the rock formation.

[0033] (2) The present invention uses alkaline silicon-based activators to activate multi-source coal-based solid waste to replace cement, thereby reducing filling costs and achieving large-scale utilization of coal-based solid waste. Salt-resistant corrosion agents are used to improve the filling body's resistance to mine water corrosion. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection.

[0035] The present invention aims to solve three main technical problems:

[0036] 1. Goaf fire control problem: Goaf fire is a serious problem in mining projects, threatening life safety, equipment integrity and environmental protection. This technology provides a method to effectively prevent and control the occurrence of fire in the goaf through reasonable smoke injection and monitoring measures. This technology solves the problem of goaf fire control.

[0037] 2. Problems of power plant flue gas emission reduction and resource utilization: The flue gas emitted by industrial processes contains a large amount of pollutants and greenhouse gases, which pose a threat to the environment and air quality. Another goal of this technology is to reduce these emissions by introducing power plant flue gas into the goaf and capturing and recycling the emissions in the process. The multi-source coal-based solid waste such as gangue, fly ash, mining sewage and carbon dioxide are made into goaf filling materials, while realizing the mineralization, storage and utilization of mining solid waste, sewage and carbon dioxide, as well as controlling the migration of rock formations. It is a very promising green and low-carbon coal mining method. This technology solves the problem of power plant flue gas emission reduction and resource recycling.

[0038] 3. Mine water corrosion problem on filling materials: A method for preparing a multi-source coal-based solid waste filling body that is resistant to mine water corrosion is provided. By adding an alkaline silicon-based activator to activate the activity of coal gangue powder and fly ash, and adding a salt-resistant corrosion agent, the purpose of replacing cement and improving the strength and corrosion resistance of the filling body is achieved.

[0039] In order to achieve the above-mentioned object, the present invention provides a mining damage control method for multi-media carbon pollution coordinated reduction and control and resource utilization, comprising the following steps:

[0040] The filling liquid and the filling material are stirred and mixed while carbon dioxide gas is introduced to form a filling slurry;

[0041] Then, the filling pipe is sprayed in an all-round shower-like manner to the goaf, and the goaf and the top and bottom plate surfaces are fully sealed;

[0042] The sealed goaf is fully grouted until it fills the goaf. Carbon dioxide is introduced into the goaf during the full grouting. The injection rate and pressure of the filling slurry and carbon dioxide into the goaf are controlled to maintain the carbon dioxide mineralization rate and low oxygen concentration in the goaf.

[0043] Monitor and analyze the underground behavior, rock reaction and rock formation stability of carbon dioxide in the backfill area. When there is groundwater in the storage area, establish a groundwater monitoring system to monitor the water quality of the groundwater;

[0044] The filling liquid includes alkaline silicon-based activator and mine wastewater, and the filling material includes coal-based solid waste and salt-resistant corrosion agent.

[0045] It should be noted that by injecting the treated flue gas from the power plant into the goaf and mixing it with the filling materials, the oxygen concentration in the goaf can be effectively reduced, fires in the goaf can be prevented and controlled, mining disasters in the goaf can be effectively controlled, and the stability of the rock formation can be increased.

[0046] By using alkaline silicon-based activators to activate multi-source coal-based solid waste to replace cement, the filling cost can be reduced and large-scale utilization of coal-based solid waste can be achieved. Salt-resistant corrosion agents can be used to improve the filling body's resistance to mine water corrosion.

[0047] Analyze rock formation reaction, establish a groundwater monitoring system, monitor groundwater quality and water level, detect whether groundwater is affected by injected carbon dioxide, and whether abnormal water level changes have occurred. Regularly collect rock and groundwater samples, conduct pH analysis, and check whether groundwater acidification has occurred, which may have an adverse effect on rock stability; use geological monitoring equipment to monitor rocks around goafs, including displacement, crack expansion, etc., to detect any signs of rock instability as early as possible. If the analysis results show that there is a risk of rock instability, targeted measures need to be taken, such as increasing support or taking other rock reinforcement measures.

[0048] In a further implementation of this embodiment, the carbon dioxide delivery system should ensure that the temperature of the carbon dioxide is between 27 and 32°C and the pressure is controlled at 1 MPa to 6 MPa to adapt to the underground environment of the goaf, while facilitating the dissolution and diffusion of carbon dioxide. A gas flow meter is installed in the delivery system to measure the volume flow of carbon dioxide.

[0049] In a further implementation of this embodiment, the total amount M of carbon dioxide injected into the goaf is calculated by the following formula:

[0050] M=Qt×ρ C +(V-V')k

[0051] Where M is the total amount of carbon dioxide injected into the goaf; V is the volume of the goaf to be filled obtained from geological survey or underground exploration, V' is the volume of carbon dioxide injected, Q is the volume flow rate of injected carbon dioxide, and t is the injection time; ρ C is the density of carbon dioxide, k is the safety factor, which is related to the composition of the filling slurry, solidification conditions, size and shape of the goaf, properties and stability of the rock, and is obtained through laboratory tests and numerical simulations designed according to specific projects, taking into account the safety margin.

[0052] In a further implementation of this embodiment, the injection amount of the filling slurry required is calculated by the following formula:

[0053] V 注 =VW 浆 ρ 浆

[0054] Where V is the volume of the goaf; W 浆 It indicates the percentage of solid filling material in the filling slurry, usually between 45% and 85%, and the specific concentration should be adjusted according to the project requirements;浆 Indicates the density of the filling slurry, which depends on factors such as the composition and water content of the filling slurry.

[0055] In a further implementation of this embodiment, in order to ensure the stability of the rock formation and the mineralization rate of the coal-based solid waste, the minimum injection pressure of carbon dioxide P is set according to the depth of the goaf and the characteristics of the rock formation. min for:

[0056] P min =P 地表 +ρgh

[0057] Where: P min is the minimum injection pressure; Psurface is the surface atmospheric pressure, which is approximately 101.3 kPa under standard atmospheric pressure; ρ is the rock density; g is the standard gravitational acceleration; h is the depth of the goaf.

[0058] In a further embodiment of this embodiment, the viscosity of the filling slurry is 450-1000 mPa.s, the pH value is 8-12, the solidification time is 50-800 min, and the carbon fixation rate is 5.6-35.8 mgCO 2 / g; after filling, the initial compressive strength without corrosion is greater than 1.4MPa, the compressive strength after corrosion is greater than 1.3MPa, and the strength corrosion resistance rate is about 91%.

[0059] In a further implementation of this embodiment, detailed geological exploration is also included:

[0060] Explore information on geological landforms, lithology, structural faults, stratum inclination, etc. to ensure that there are no obvious geological defects in the area. Use rangefinders and underground exploration equipment to measure the spatial size and shape of the goaf, obtain the length, width and height information of the goaf, select appropriate injection points, and ensure safe sealing and filling.

[0061] It should be noted that: carry out detailed geological exploration, including information on geological landforms, lithology, structural faults, and formation dips; use geological exploration techniques such as seismic exploration, geological radar, and core drilling to obtain key geological information; ensure that there are no obvious geological defects in the area, such as ground fissures or cracks. Measure parameters such as the strength and elastic modulus of the rock mass, the consistency of the rock, analyze the groundwater level and water flow direction, and evaluate the ventilation conditions of the goaf to ensure the safety of the staff; use rangefinders and underground exploration equipment to measure the spatial size and shape of the goaf, obtain information on the length, width, and height of the goaf, and select appropriate injection points to ensure safe sealing and filling.

[0062] In a further implementation of this embodiment, the carbon dioxide is obtained by purifying and capturing flue gas from a power plant, specifically:

[0063] The flue gas from the power plant is first passed through purification equipment to remove solid particles, sulfur compounds, nitrogen oxides and other harmful substances. Appropriate ventilation ducts and connecting devices are installed to guide the flue gas from the power plant to the capture equipment to enrich carbon dioxide. Before and after the capture equipment, the flue gas characteristics are tested and analyzed, and the carbon dioxide concentration, temperature, pressure and other parameters in the flue gas are tested.

[0064] In a further implementation of this embodiment, before the flue gas from the power plant enters the capture equipment, a gas flow meter is installed to measure the volume flow of the flue gas, and this value is recorded and marked as Q. The temperature of the transported flue gas is lower than 31°C and the pressure is controlled at 1-6MPa.

[0065] In a further implementation of this embodiment, the filling material includes the following materials in percentage by mass:

[0066] 15% to 26% of coal gangue, 5% to 10% of blast furnace slag, 35% to 49% of fly ash, 16% to 24% of desulfurized gypsum, 10% to 17% of gasified slag, 9% to 18% of bottom ash, and 0.5% to 2% of salt-resistant corrosion agent;

[0067] The preparation method of the filling material is: respectively add coal gangue, blast furnace slag, fly ash, desulfurized gypsum, gasified slag, bottom slag, and salt-resistant corrosion agent into a ball mill for ball milling for 30 to 60 minutes, and continuously stir the mixed powder after ball milling with the filling liquid for 5 to 20 minutes at a stirring rate of 1000 to 10000 r / min.

[0068] It should be noted that: CO2 is used to mineralize multi-source coal-based solid waste to prepare goaf filling slurry. The mining sewage is treated by sedimentation, filtration, flocculation and neutralization to obtain sludge and mine wastewater. The sludge is concentrated and dehydrated to reduce the volume, which is convenient for subsequent disposal or resource utilization.

[0069] The gangue is crushed and screened to obtain an appropriate particle size (for example: 6mm~20mm), and materials such as blast furnace slag, fly ash, desulfurization gypsum, gasified slag, bottom ash, salt-resistant agent and alkaline activator are mixed in proportion (solid-liquid ratio is 7:3; solid ratio is 15%~26% of gangue, 5%~10% of blast furnace slag, 35%~49% of fly ash, 16%~24% of desulfurization gypsum, 10%~17% of gasified slag, 9%~18% of bottom ash, 0.5%~2% of salt-resistant agent; liquid ratio is 10% of activator and 90% of mine water) to prepare the raw materials of solid waste filling materials.

[0070] Inject carbon dioxide gas into the mixture to form mineralized multi-source coal-based solid waste filling slurry, and fill the filling slurry into the goaf from the injection point; calculate the total storage capacity of carbon dioxide injected into the goaf, and evaluate the sealing effect as well as environmental protection and resource utilization; determine the required grouting according to the goaf conditions, filling slurry concentration and density; calculate the injection pressure according to the depth of the goaf and the rock characteristics.

[0071] During the injection of carbon dioxide, gas leakage prevention is also required. Leakage detectors and sealing devices should be installed in the carbon dioxide injection system to promptly detect and repair potential gas leaks. A gas concentration monitoring system should be installed to monitor the concentration of the injected gas in real time. If the concentration exceeds the safe range, the system will sound an alarm and take appropriate measures. The composition and amount of the injected gas should be monitored and adjusted at any time to ensure that the gas composition in the goaf remains at a safe level.

[0072] The injection process requires monitoring and recording of parameters such as flow, pressure and temperature to ensure precise control. Control of the injection rate is critical. Too fast a rate may lead to abnormal pressure increase, thereby increasing the risk of geological fracturing and fire, and too slow a rate may reduce injection efficiency. Closely monitor the temperature, pressure and gas concentration in the goaf. If abnormal conditions are found, take immediate measures, such as stopping injection or adjusting injection parameters, to ensure the safety of the goaf. After injection, continuous monitoring and recording are carried out to ensure the stability of the goaf and the uniformity of carbon dioxide density.

[0073] The injected CO2 interacts with coal-based solid waste and rocks in the reservoir through physical adsorption, dissolution and mineral reaction. During the mineralization process, the raw materials first undergo hydration reaction to form CaCO 3 , Ca(OH) 2 and CSH gel, which then reacts with carbon dioxide to form SiO 2 Silica gel and CSH gel, further hydration reaction promotes the volcanic ash reaction, generating more hydration products. The mixture reaction consumes a lot of water, causing the slurry to gradually lose fluidity and begin to harden in a short time. In addition, the alkaline activator not only forms a gel structure in the mixture, but also promotes the volcanic ash reaction, causing the system to lose consistency in a short time and form a dense material. The reaction equation is as follows:

[0074] (3-a)CO 2 +C 3 S+B 2 O→C a SH b +(3-a)CaCO 3

[0075] 3H+C 3 S→2CH+CSH

[0076] 2H+C 2 S→CH+C-S-H

[0077] CO 2 +C-S-H→SiO 2 (gel)+CaCO 3 +xH 2 O

[0078] CO 2 +Ca(OH) 2 →H 2 O+CaCO 3

[0079] CO 2 +Na 2 SiO 3 →Na 2 CO 3 +SiO 2 (gel)

[0080] mCa(OH) 2 +Na 2 SiO 3 +nH 2 O→2NaOH+mCaO·SiO 2 ·nH 2 O

[0081] 3OH - +≡O-Si-O≡→[SiO(OH) 3 ] -

[0082] 7OH - +≡Si-O-Al→[Al(OH) 4 ] - +[SiO(OH) 3 ] -

[0083] m[SiO(OH) 3 ] - +lCa 2+ +(n-m-l)H 2 O+(2l-m)OH - →C l S m H n

[0084] 4Ca 2+ +6OH - +2[Al(OH) 4 ] - +6H 2 O→C4 AH 13

[0085] As CO2 is injected, the pH of groundwater and rock changes, making it more acidic. Some underground rocks can react with CO2 to form carbonate minerals. These reactions can lead to long-term storage of CO2 and the formation of carbonate minerals. Rock reaction analysis is an ongoing process that should be monitored and evaluated regularly to ensure the stability of the goaf and surrounding rock formations.

[0086] Example 1

[0087] Step 1. Install appropriate ventilation ducts and connecting devices to ensure that the flue gas generated by the power plant combustion is effectively guided from the chimney, and the flue gas is sequentially passed through the desulfurization tower, spray tower and cooling system for desulfurization, denitrification, dehumidification, cooling and dust removal. The flue gas from the power plant is guided to the capture equipment (adsorbent bed) to enrich carbon dioxide, and the gas transmission pipeline uses corrosion-resistant and high-pressure mining plastic-coated composite steel pipes. Before the flue gas enters the capture equipment, install a gas flow meter to measure the volume flow of the flue gas. Record and mark this value as Q (flue gas). Before and after the capture equipment, the flue gas characteristics are tested to detect parameters such as the carbon dioxide concentration, temperature, and pressure in the flue gas.

[0088] Step 2: The treated flue gas from the power plant is drawn out from the power plant through a fan and compressed by a centrifugal compressor using multi-stage compression to compress and boost the flue gas. The compressed high-pressure flue gas enters the cooling unit, and a coolant is used to cool the high-temperature and high-pressure flue gas to below 31°C. Carbon dioxide is extracted and stored from the cooling unit and transported to the gas storage tank by a gas pipeline for subsequent injection. Throughout the compression process, temperature, pressure, and liquid flow need to be continuously monitored and controlled to ensure that the operation is within a safe range and to obtain the required carbon dioxide production.

[0089] Step 3: Use seismic exploration, geological radar, core drilling and other geological exploration technologies to obtain key geological information and determine that there are no obvious geological defects such as ground fissures or cracks. Measure the strength, elastic modulus, consistency and other parameters of the rock mass, analyze the groundwater level and water flow direction, evaluate the ventilation of the goaf, and ensure safe sealing and filling. Use rangefinders and underground exploration equipment to measure the spatial size and shape of the goaf, and obtain the length of the goaf as 37m, the width as 150m, and the height as 5m.

[0090] The coal gangue used to prepare the filling slurry is taken from the gangue yard of the coal mine. The main oxide component is SiO 2 , Al 2 O 3 , Fe 2 O 3 and K 2 O, the main mineral phases are quartz and kaolinite, etc.

[0091] Hard, the main rock types are shale, sandstone and mudstone, the appearance is gray and gray-black, non-self-igniting, the average uniaxial compressive strength is 30-40MPa, and the density is about 2.350kg / m 3 , the bulk density is about 1.400kg / m 3 .

[0092] The particle size after crushing and screening is 6mm~20mm, the moisture content is 5%, and the main oxide component of the selected fly ash is SiO 2 , Al 2 O 3 , Fe 2 O 3 and CaO, with a mass fraction of more than 87%, and the main mineral phases are quartz and mullite, etc.

[0093] The mass fraction of fly ash with particle size less than 50μm and less than 180μm exceeds 50% and 90% respectively. It is off-white in appearance and has a density of about 2.150kg / m 3 The alkaline activator is sodium silicate and sodium hydroxide with a purity of 99.9%.

[0094] The mining wastewater is treated by sedimentation, filtration, flocculation and neutralization to obtain sludge and filling water. The sludge is concentrated and dehydrated to reduce its volume for subsequent disposal or resource utilization.

[0095] Blast furnace slag, fly ash, desulfurized gypsum, gasified slag, bottom ash, salt-resistant agent and alkaline activator and other materials are mixed in proportion (solid-liquid ratio is 7:3; solid ratio is 15%-26% of coal gangue, 5%-10% of blast furnace slag, 35%-49% of fly ash, 16%-24% of desulfurized gypsum, 10%-17% of gasified slag, 9%-18% of bottom ash, 0.5%-2% of salt-resistant agent; liquid ratio is 10% of activator and 90% of mine water) to prepare raw materials for solid waste filling materials.

[0096] Carbon dioxide gas is injected into the mixture to form mineralized multi-source coal-based solid waste filling slurry, and the filling slurry is filled into the goaf from the injection point.

[0097] Calculate the total storage volume of carbon dioxide injected into the goaf and evaluate the storage effect as well as environmental protection and resource utilization.

[0098] The required grouting is determined based on the goaf conditions, filling slurry concentration and density. The injection pressure is calculated based on the goaf depth and rock formation characteristics.

[0099] Step 4: Determine the pressure P injected into the coal seam goaf by the formula (注入) for

[0100] P注入 =P 地表 +ρgh=3.6MPa

[0101] Where: P (注入) is the injection pressure, (Pa). (地表) is the atmospheric pressure at the surface, 101.3 kilopascals (kPa). ρ is the rock density, (kg / m 3 ). g is 9.81 meters per second squared (m / s 2 ). h is the depth of the goaf, in meters (m).

[0102] Step 5: The flue gas from the gas storage tank flows out in two ways, one is transported to the underground goaf through the filling pipeline, and the other enters the booster station. Since the centrifugal compressor's own adjustment capacity is 76% to 100%, and the amount of flue gas injected underground is not completely constant, the amount of flue gas injected can be adjusted and controlled by the centrifugal compressor and the booster.

[0103] When the flue gas delivery volume is less than the design value, the pressure of the gas tank exceeds the standard, and the compressor is adjusted to reduce the gas supply. At this time, the centrifugal compressor is turned off, the booster is turned on, and the flue gas delivery volume is adjusted by the booster. When the pressure of the gas tank is lower than the standard value, the centrifugal compressor starts and the booster stops working. The ground part of the pipeline can be laid on the ground or underground according to the actual situation. When injecting gas underground, buried pipe injection is used, and two gas injection pipelines are buried in the air intake tunnel of the fully mechanized working face. One of the gas injection pipelines is buried in the middle of the open cut, with the pipe mouth facing upward, 0.5m to 2.5m away from the bottom plate, and an isolation cover is set on the top to prevent foreign objects from falling into the pipe. Wooden piles are built around the pipe to connect the top. The other gas injection pipeline is buried in the oxidation zone of the goaf, and an isolation cover is set at the pipe mouth to prevent coal and rock from falling and blocking the pipe mouth.

[0104] After the mining face reaches the designed distance, the filling material and flue gas are injected. The gas injection pipeline can be connected with the original nitrogen injection or filling pipeline for gas injection. Gas injection is carried out for 24 hours a day. When the carbon dioxide concentration in the return airway reaches 1.5% or the gas concentration reaches 1%, the gas injection is stopped.

[0105] During the injection process, parameters such as flow, pressure and temperature are monitored and recorded to ensure precise control. Leak detectors and sealing devices are installed in the injection system to detect and repair potential gas leaks in a timely manner. The injection rate is controlled and the temperature, pressure and gas concentration in the goaf are closely monitored. If abnormal conditions are found, measures such as stopping injection or adjusting injection parameters are taken immediately. After injection, continuous monitoring and recording are carried out to ensure the stability of the goaf and the uniformity of CO2 density.

[0106] Step 6. Establish a groundwater monitoring system to monitor the quality and level of groundwater. Detect whether the groundwater is affected by the injected carbon dioxide and whether abnormal water level changes have occurred. Collect samples of rock formations and groundwater regularly, conduct pH analysis, and check whether groundwater acidification has occurred. Use geological monitoring equipment to monitor the rocks around the goaf, including displacement, crack expansion, etc. If the analysis results show that there is a risk of rock instability, additional support or other rock reinforcement measures need to be taken.

[0107] Step 7: Calculate the total storage volume of carbon dioxide that has been successfully injected into the goaf and evaluate the storage effect. The total storage volume of injected carbon dioxide M is calculated using the following formula:

[0108] M=ρ C V=Qt×ρ C

[0109] Where M is the total storage volume of injected CO2. V is the volume of liquefied CO2 injected into the goaf. This is calculated by the volume flow rate Q of the flue gas injected in step 2, and t is the injection time. ρC is the density of liquefied CO2.

[0110] Comparative Example

[0111] The difference from the embodiment is that no salt corrosion resistance agent is added.

[0112] The uniaxial compressive strength of the coal-based solid waste filling body resistant to mine water corrosion before and after corrosion was compared, and the uniaxial compressive strength test of the filling body before and after corrosion was carried out using a Z250 electronic universal testing machine with a loading rate of 0.5 mm / min. The results are shown in Table 1.

[0113] Table 1 Experimental results

[0114] Group Compressive strength before corrosion / MPa Compressive strength after corrosion / MPa Corrosion resistance rate / % Comparative Example 1.47 0.75 51.02 Example 1.45 1.32 91.03

[0115] From the above results, it can be found that compared with the control example without adding salt-resistant corrosion agents, after adding salt-resistant corrosion agents in the embodiment, the compressive strength of the filling body after corrosion is lower than that of the uncorroded group, but the decrease in compressive strength of the filling body with corrosion-resistant additives is smaller than that of the control example, and the corrosion resistance rate is greatly improved.

[0116] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A mining damage control method for multi-media carbon pollution coordinated reduction and resource utilization, characterized by: The following steps are involved: The filling liquid and the filling material are stirred and mixed while carbon dioxide gas is introduced to form a filling slurry; Then, the filling pipe is sprayed in an all-round shower-like manner to the goaf, and the side walls, roof and floor surfaces of the goaf are fully sealed; The sealed goaf is fully grouted until it fills the goaf. Carbon dioxide is introduced into the goaf during the full grouting. The injection rate and pressure of the filling slurry and carbon dioxide into the goaf are controlled to maintain the carbon dioxide mineralization rate and low oxygen concentration in the goaf. Monitor and analyze the underground behavior, rock reaction and rock formation stability of carbon dioxide in the backfill area. When there is groundwater in the storage area, establish a groundwater monitoring system to monitor the water quality of the groundwater; The filling liquid includes alkaline silicon-based activator and mine wastewater, and the filling material includes coal-based solid waste and salt-resistant corrosion agent.

2. The mining damage control method for multi-media carbon pollution coordinated reduction and resource utilization according to claim 1 is characterized by: The temperature of the carbon dioxide introduced into the goaf is 27-32° C. and the pressure is 1 MPa-6 MPa.

3. The mining damage control method for multi-media carbon pollution coordinated reduction and resource utilization according to claim 1 is characterized by: The total amount M of carbon dioxide injected into the goaf is calculated by the following formula: M=Qt×ρ C +(V-V')k Where M is the total amount of carbon dioxide injected into the goaf; V is the volume of the goaf to be filled obtained from geological survey or underground exploration, V' is the volume of carbon dioxide injected, Q is the volume flow rate of injected carbon dioxide, and t is the injection time; ρ C is the density of carbon dioxide and k is the safety factor.

4. The mining damage control method for multi-media carbon pollution coordinated reduction and resource utilization according to claim 1 is characterized by: The required injection amount of the filling slurry is calculated by the following formula: V 注 =VW 浆 ρ 浆 Where V is the volume of the goaf; W 浆 Indicates the percentage of solid filling material in the filling slurry; ρ 浆 represents the density of the filling slurry, where W 浆 It is 45%-85%.

5. The mining damage control method for multi-media carbon pollution coordinated reduction and resource utilization according to claim 1 is characterized by: In order to ensure the stability of the rock formation and the mineralization rate of coal-based solid waste, the minimum injection pressure of carbon dioxide P is determined according to the depth of the goaf and the characteristics of the rock formation. min for: P min =P 地表 +ρgh Where: P min is the minimum injection pressure; P 地表 is the surface atmospheric pressure; ρ is the rock density; g is the standard acceleration of gravity; h is the depth of the goaf.

6. The mining damage control method for multi-media carbon pollution coordinated reduction and resource utilization according to claim 1 is characterized by: The filling slurry has a viscosity of 450-1000 mPa.s, a pH value of 8-12, a solidification time of 50-800 min, and a carbon fixation rate of 5.6-35.8 mgCO2 / g; after filling, the initial uncorroded compressive strength is greater than 1.4 MPa, the compressive strength after corrosion is greater than 1.3 MPa, and the strength corrosion resistance rate is about 91%.

7. The mining damage control method for multi-media carbon pollution coordinated reduction and resource utilization according to claim 1 is characterized by: It also includes detailed geological surveys: Explore information on geological landforms, lithology, structural faults, and stratum dips to ensure that there are no obvious geological defects in the area; use rangefinders and underground exploration equipment to measure the spatial size and shape of the goaf, obtain information on the length, width, and height of the goaf, select appropriate injection points, and ensure safe sealing and filling.

8. The mining damage control method for multi-media carbon pollution coordinated reduction and resource utilization according to claim 1 is characterized by: The carbon dioxide is obtained by purifying and capturing flue gas from a power plant, specifically: The flue gas from the power plant is first passed through purification equipment to remove solid particles, sulfur compounds, nitrogen oxides and other harmful substances. Appropriate ventilation ducts and connecting devices are installed to guide the flue gas from the power plant to the capture equipment to enrich carbon dioxide. Before and after the capture equipment, the flue gas characteristics are tested and analyzed, and the carbon dioxide concentration, temperature, pressure and other parameters in the flue gas are tested.

9. The mining damage control method for multi-media carbon pollution coordinated reduction and resource utilization according to claim 1 is characterized by: Before the flue gas from the power plant enters the capture equipment, a gas flow meter is installed to measure the volume flow of the flue gas. This value is recorded and marked as Q. The temperature of the conveyed flue gas is lower than 31°C and the pressure is controlled at 1 to 6 MPa.

10. The mining damage control method for multi-media carbon pollution coordinated reduction and resource utilization according to claim 1 is characterized in that: The filling material includes the following materials in percentage by mass: 15% to 26% of coal gangue, 5% to 10% of blast furnace slag, 35% to 49% of fly ash, 16% to 24% of desulfurized gypsum, 10% to 17% of gasified slag, 9% to 18% of bottom ash, and 0.5% to 2% of salt-resistant corrosion agent; The preparation method of the filling material is: respectively add coal gangue, blast furnace slag, fly ash, desulfurized gypsum, gasified slag, bottom slag, and salt-resistant corrosion agent into a ball mill for ball milling for 30 to 60 minutes, and continuously stir the mixed powder after ball milling with the filling liquid for 5 to 20 minutes at a stirring rate of 1000 to 10000 r / min.