A method for constructing a carbon storage space by artificially recreating a key layer sealing

Abstract

The application discloses a kind of artificial reconstruction plugging key layer's carbon storage space construction method, steps are as follows: S1, carries out geological detection, determines the thickness and lithology of each rock layer overlying;S2, based on theoretical analysis and measured data determines the height of gas guide fracture zone generated after coal seam uses filling mining;S3, based on geological data and gas guide fracture zone height, determine the position of artificial reconstruction plugging key layer and grouting horizon;S4, carries out filling mining, and overburden is grouted to reconstruct plugging key layer, forms carbon storage space;S5, by pipeline injects carbon dioxide gas into goaf, while carbon filling in working face carries out carbon dioxide concentration monitoring, carries out surface rock movement monitoring on surface, judges carbon filling effect.The application can effectively utilize coal mine post-mining space to store carbon dioxide and effectively reduce greenhouse gas emissions by filling waste rock and forming carbon storage space through artificial reconstruction plugging key layer.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of carbon storage and mining, and particularly relates to a carbon storage space construction method for artificially re-creating a key layer blocking layer. BACKGROUND

[0002] The mine solid waste filling mining technology is an important technical approach for realizing green and low-carbon development of the mining industry. The mine filling mining technology can realize maximum recovery of mineral resources and environmental protection disposal of mine solid wastes. The filling mining technology has significant technical advantages in surface subsidence control, ecological environment protection, mine solid waste disposal and utilization, and can solve the problems of surface subsidence, underground water loss, gas emission and land occupation damage from the source of coal resource mining.

[0003] In the process of coal mining, most mining areas in China are faced with the problem of large carbon emission, so adopting the carbon storage technology to reduce carbon dioxide emission becomes a feasible measure. However, the existing carbon storage technology has high requirements for the geological conditions of the carbon storage layer, and has the problems of poor applicability and limited carbon storage space. The new filling material with high porosity, high strength and high carbon storage capacity is used to mix carbon dioxide, coal gangue and rapid cementing material underground, construct the mixed filling material and fill it into the goaf to form a rapid and efficient cementing high-porosity carbon negative filling body. The carbon dioxide storage body is formed while realizing high-porosity filling, which can realize goaf filling and reduce surface subsidence and carbon emission. When the working face is near the overlying strata with hard and thick rock layers, the hard and thick rock layers can play a role in isolating carbon dioxide, and when the overlying strata near the working face do not have hard rock layers, it is necessary to construct an artificially re-created key layer blocking layer to realize carbon negative mining. Therefore, the development of a carbon storage space construction method for artificially re-creating a key layer blocking layer has considerable theoretical and practical significance for the development of green coal mining technology. SUMMARY

[0004] The purpose of the application is to provide a carbon storage space construction method for artificially re-creating a key layer blocking layer, which can effectively utilize the post-mining space of the coal mine to store carbon dioxide and effectively reduce the emission of greenhouse gases while filling and disposing of gangue.

[0005] The technical scheme is a carbon storage space construction method for artificially re-creating a key layer blocking layer, which comprises the following steps:

[0006] S1, geological exploration is performed to determine the thickness and lithology of each overlying rock layer;

[0007] S2, the height of the gas guide fracture zone generated after the coal seam is mined by filling is determined based on theoretical analysis and measured data;

[0008] S3, based on geological data and gas-guided fracture zone height, determine the position of the artificial reconstruction of the key layer and the grouting horizon;

[0009] S4, conduct filling mining, grout the key layer of the overburden rock to form a carbon storage space;

[0010] S5, inject carbon dioxide gas into the goaf through the pipeline, monitor the carbon dioxide concentration in the working face during negative carbon filling, and monitor the surface rock movement on the ground to determine the effect of negative carbon filling.

[0011] Further, during filling mining, the carbon dioxide filling pipeline is preset every 50-300m of working face advancement.

[0012] Further, according to porosity and permeability, select grouting rock layers.

[0013] Further, in step S5, carbon dioxide gas is injected into the goaf through the pipeline to form the filling material and adsorb carbon dioxide in the working face, and the filling and carbon sequestration effects are evaluated through the monitoring results of surface subsidence monitoring and carbon dioxide concentration monitoring; wherein, the surface subsidence monitoring includes: monitoring the surface subsidence range, surface subsidence value, surface subsidence with working face advancement law and surface subsidence stable time.

[0014] In any of the above artificial reconstruction of the key layer carbon storage space construction methods, the grouting position of the artificial reconstruction of the key layer is determined by the grouting horizon depth:

[0015] If the depth is shallow, vertical drilling is performed from the ground to the grouting horizon for grouting and sealing;

[0016] If the depth is deep, inclined drilling is performed from the adjacent working face recovery roadway to the grouting horizon for grouting and sealing.

[0017] Compared with the prior art, the present application has the following remarkable effects:

[0018] 1. The present application constructs an artificial reconstruction of the key layer, by injecting carbon dioxide into the artificial reconstruction of the carbon storage space, which can effectively store a large amount of carbon dioxide and reduce greenhouse gas emissions; at the same time, waste such as gangue and ash is mixed with carbon dioxide to form a filling material during the filling process, which not only solves the problem of mine waste disposal, but also reduces environmental pollution;

[0019] 2. In terms of safety, artificially re-creating the key layer sealing can control the height of the gas-guiding fracture zone, reduce the damage degree of the overlying strata, thereby reducing the influence of stress on the mining process and improving the mining safety; in the mining process, the construction of the closed wall can also isolate the goaf from the working area to prevent gas from escaping to the working area, thereby protecting the health of the workers; the carbon storage space construction technology of artificially re-creating the key layer sealing is an important technical means to promote green mining of coal mines, which is helpful to promote the upgrading and transformation of coal mining technology and further promote the development of filling mining theory and technology, and provides valuable experience and demonstration for other similar coal mine work. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a flowchart of the present application;

[0021] Figure 2 is a structural schematic diagram of the carbon storage space of the artificially re-created key layer sealing of the present application;

[0022] Figure 3 is a schematic diagram of the gas injection pipeline arrangement of the artificially re-created key layer sealing of the present application. DETAILED DESCRIPTION

[0023] The present application will be further described in detail below in combination with the drawings and specific embodiments of the present application.

[0024] As Figure 1 shown is a flowchart of the carbon storage space construction method of the artificially re-created key layer sealing of the present application, mainly including the following steps: in actual operation, geological exploration is carried out to determine the thickness and lithology of each overlying stratum, the height of the gas-guiding fracture zone generated after the coal seam adopts filling mining is determined based on theoretical analysis and measured data; based on the geological data and the height of the gas-guiding fracture zone, the position of the artificially re-created key layer sealing and the grouting horizon are determined; filling mining is carried out, wherein the carbon dioxide injection pipeline is preset every 50-300 m of the working face advancement; the overlying strata are grouted to re-create the key layer sealing to form a carbon storage space; carbon dioxide and other gases are injected into the goaf through the pipeline, the carbon dioxide concentration is monitored at the working face during the carbon negative filling, the ground displacement is monitored on the ground, and the carbon negative filling effect is judged.

[0025] A certain mine is planned to carry out carbon negative grouting filling on the working face which is ready to be mined by the full caving method in order to reduce the carbon emission of the mine and further reduce the surface subsidence. The working face is 220 m long, the advancement length is about 2500 m, the coal seam thickness is about 3.5 m, the overburden strata void ratio is 40%, and the buried depth is 800 m.

[0026] The specific steps are as follows:

[0027] Step 1, geological exploration is conducted to determine the thickness and lithology of each overlying rock layer, and the height of the gas-guiding fractured zone generated after the coal seam is mined by filling is determined based on theoretical analysis and measured data;

[0028] Firstly, the overlying rock strata of the working face are sampled, and the void ratio and various strength and other mechanical properties of the rock sample are tested. The height of the gas-guiding fractured zone generated after the working face is mined by filling is determined by comprehensively considering the mining depth of the working face, the occurrence factors of the rock strata, and the mechanical properties of the rock strata, and is preliminarily determined to be 35 m.

[0029] Step 2, based on the geological data and the height of the gas-guiding fractured zone, the position of the artificially reconstructed sealing key layer and the grouting horizon are determined;

[0030] Further, the position of the artificially reconstructed sealing key layer is generally located above the gas-guiding fractured zone, and the grouting horizon is generally located in the separation zone or the fractured zone.

[0031] Further, the grouting position of the artificially reconstructed sealing key layer is determined by the burial depth of the grouting horizon:

[0032] If the burial depth is shallow, a vertical drill hole can be constructed from the ground to the grouting horizon for grouting and sealing;

[0033] If the burial depth is deep, an inclined drill hole can be constructed from the adjacent working face recovery roadway underground to the grouting horizon for grouting and sealing. After the drill hole grouting is completed, it needs to be sealed in time to prevent carbon dioxide gas leakage.

[0034] Step 3, filling mining is conducted, and the carbon dioxide filling pipeline is preset every 50-300 m of working face advancement;

[0035] During the mining process, the filling material is transported to the inside of the goaf through the pipeline or transportation equipment for filling to support the surrounding rock mass of the goaf. In addition, in order to smoothly fill carbon dioxide to the working face after the recovery work is completed, the method of presetting the carbon dioxide filling pipeline every 50-300 m of working face advancement lays a foundation for subsequent carbon dioxide filling and negative carbon mining.

[0036] Step 4, the overlying rock is grouted to reconstruct the sealing key layer to form a carbon storage space;

[0037] The roof is grouted, and the specific proportion of the slurry is: fly ash 45%, gangue 40%, cement 10%, quicklime 2%, and accelerator 3%. The mixed material is mixed with water to prepare grouting and filling material with a mass concentration of 82%. The fluidity and coagulability of the slurry are used to fill and reinforce the weak parts, further enhance the integrity and strength of the rock mass, and form an artificially reconstructed sealing key layer, such as Figure 2The filling process is shown. During the filling process, the fluidity of the slurry is tested to ensure that the grouting filling material has good conveying performance; the gangue is discharged through the porous bottom unloading conveyor, and the rapid binding material is sprayed through the pipeline + pump.

[0038] Before artificially recreating the key layer, the lithology of the overlying strata and the grouting area needs to be determined. Through geological exploration, well logging data analysis and other means, the lithology of the overlying strata and the grouting area can be preliminarily judged. The grouting strata generally need to have high porosity and permeability, so sandstone layers should be the main choice for grouting strata.

[0039] According to the broken condition of the rock mass in the grouting area, the grouting pressure is determined. When the rock mass is severely broken, the grouting pressure should be about 0.5 MPa, when it is relatively broken, about 1 MPa, and when the fracture is less developed, the grouting pressure can be 1-2 MPa. The mine has a deep depth, so inclined drill holes should be constructed from the adjacent working face roadway to the grouting layer to perform grouting and plugging, so that the process of artificially recreating the key layer does not have a large impact on the carbon storage space.

[0040] Step 5, injecting carbon dioxide and other gases into the goaf through the carbon dioxide injection pipeline, as shown in Figure 3 The negative carbon filling is monitored at the same time as the carbon dioxide concentration monitoring at the working face and the surface ground movement monitoring at the surface to determine the negative carbon filling effect.

[0041] Carbon dioxide and other gases are injected into the goaf through the pipeline to form the filling material and adsorb the carbon dioxide in the working face. The filling and carbon sequestration effects are evaluated through the monitoring results of the surface subsidence monitoring and the carbon dioxide concentration monitoring. The surface subsidence monitoring includes monitoring the surface subsidence range, surface subsidence value, surface subsidence law with working face advancement, and surface subsidence stabilization time. The carbon dioxide concentration monitoring monitors the carbon dioxide concentration at the working face. If the carbon dioxide concentration abnormally increases, it indicates that the carbon storage space plugging effect is not good, and supplementary grouting and plugging should be performed by adjusting the grouting pressure, grouting position or layer, etc.

[0042] Further, in this embodiment, liquid carbon dioxide is converted into gas by a water liquid vaporizer. Then, it is transported to the place where filling is needed through the grouting pipeline. During the injection process, according to the actual needs, the appropriate release position is selected to inject carbon dioxide gas into the goaf to achieve the purpose of filling and adsorbing carbon dioxide.

Claims

1. A method for constructing carbon storage space to artificially recreate and seal critical layers, characterized in that, The steps include the following: S1, conduct geological exploration to determine the thickness and lithology of the overlying rock layers; S2, based on theoretical analysis and measured data, determines the height of the gas-conducting fracture zone generated after the coal seam is mined using backfilling; S3, based on geological data and the height of the gas-conducting fracture zone, determines the location of the key layer for artificial reconstructed sealing and the grouting layer; the grouting location of the key layer for artificial reconstructed sealing is determined by the burial depth of the grouting layer: If the burial depth is shallow, vertical drilling is carried out from the ground to the grouting layer for grouting and sealing. If the burial depth is relatively deep, grouting and sealing will be carried out by drilling inclined boreholes from the mining roadway adjacent to the underground working face towards the grouting layer; S4. Conduct backfilling mining, construct a sealed wall to isolate the goaf from the working area, and pre-install carbon dioxide injection pipelines every 50-300m of working face advancement; grout the overburden to recreate and seal key layers, forming carbon storage space; S5. Inject carbon dioxide gas into the goaf through the carbon dioxide injection pipeline, monitor carbon dioxide concentration at the working face while performing negative carbon filling, and monitor surface rock movement on the surface to determine the effect of negative carbon filling.

2. The method for constructing carbon storage space for artificially recreating and sealing critical layers according to claim 1, characterized in that, The grouting rock layer is selected based on porosity and permeability.

3. The method for constructing carbon storage space for artificially recreating and sealing critical layers according to claim 1, characterized in that, In step S5, carbon dioxide gas is injected into the goaf through the carbon dioxide injection pipeline to form the filling material and adsorb carbon dioxide in the working face. At the same time, the filling and carbon fixation effects are evaluated by monitoring the results of surface subsidence and carbon dioxide concentration. Among them, surface subsidence monitoring includes: monitoring the surface subsidence range, surface subsidence value, surface subsidence pattern as the working face advances, and surface subsidence stabilization time.

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