Method for constructing carbon storage space of artificially reconstructed plugging key layer

Abstract

The invention discloses a carbon storage space construction method for an artificial reconstruction plugging key layer, and the method comprises the following steps: S1, carrying out geological exploration, and determining the thickness and lithology of each overlying rock stratum; s2, determining the height of a gas guide fissure zone generated after the coal seam is mined by filling based on theoretical analysis and actual measurement data; s3, on the basis of geological data and the height of the gas-conducting fissure zone, the position of an artificial reconstruction plugging key layer and the position of a grouting layer are determined; s4, filling mining is carried out, grouting is carried out on overlying strata to reconstruct and block a key layer, and a carbon storage space is formed; and S5, carbon dioxide gas is injected into the goaf through a pipeline, carbon dioxide concentration monitoring is conducted on the working face while negative carbon filling is conducted, earth surface rock movement monitoring is conducted on the earth surface, and the negative carbon filling effect is judged. According to the method, the carbon storage space is formed by manually rebuilding and blocking the key layer while the gangue is filled, the space after coal mining can be effectively utilized for storing carbon dioxide, and emission of greenhouse gas is effectively reduced.

Description

Technical Field

[0001] The invention relates to the technical field of negative carbon filling mining, and in particular to a method for constructing a carbon storage space for artificially recreating and plugging a key layer. Background Art

[0002] Mine solid waste filling mining technology is an important technical approach to achieve green and low-carbon development of the mining industry. Mine filling mining technology can not only achieve the maximum recovery of mineral resources, but also achieve environmentally friendly disposal of mining solid waste. Filling mining technology has significant technical advantages in surface subsidence control, ecological environmental protection, and mine solid waste disposal and utilization. It can solve problems such as surface subsidence, groundwater loss, gas emissions, and land occupation damage from the source of coal resource mining.

[0003] In the process of coal mining, most mining areas in my country face the problem of large carbon emissions. Therefore, the use of carbon sequestration technology to reduce carbon dioxide emissions has become a feasible measure. However, the existing carbon sequestration technology has high requirements for the geological conditions of carbon reservoirs, and there are problems such as poor applicability and limited carbon storage space. Using new filling materials with high porosity, high strength and high carbon storage capacity, carbon dioxide, coal gangue and fast cementing materials are mixed underground to construct mixed filling materials and fill them into the goaf to form a fast and efficient cemented high-porosity negative carbon filling body. While achieving high porosity filling, a carbon dioxide sequestration body is formed. This can not only achieve goaf filling to reduce surface subsidence, but also reduce carbon emissions. When the working face has hard and thick rock layers in the nearby overburden, the hard and thick rock layers can isolate carbon dioxide. When the nearby overburden does not have hard rock layers, it is necessary to construct artificial reconstruction and plugging key layers to achieve negative carbon mining. Therefore, developing a method to construct carbon storage space by artificially recreating and sealing key layers has considerable theoretical and practical significance for the development of green coal mining technology. Summary of the invention

[0004] Purpose of the invention: The purpose of the present invention is to provide a method for constructing a carbon storage space by artificially reconstructing and sealing the key layer, which can form a carbon storage space by artificially reconstructing and sealing the key layer while filling and disposing of the gangue, and can effectively utilize the space after coal mining to store carbon dioxide and effectively reduce greenhouse gas emissions.

[0005] Technical solution: A method for constructing a carbon storage space by artificially recreating and plugging a key layer, comprising the following steps:

[0006] S1, conduct geological survey to determine the thickness and lithology of the overlying rock layers;

[0007] S2, based on theoretical analysis and measured data, determine the height of the gas-conducting fracture zone generated after backfill mining of the coal seam;

[0008] S3, based on geological data and the height of the gas-conducting fracture zone, determine the location of the key layer for artificial reconstruction and plugging and the grouting layer;

[0009] S4, backfill mining is carried out, and grouting is performed on the overburden rock to reconstruct and seal the key layer to form a carbon storage space;

[0010] S5, inject carbon dioxide gas into the goaf through pipelines, monitor carbon dioxide concentration on the working face while performing negative carbon filling, monitor surface rock movement on the surface, and judge the effect of negative carbon filling.

[0011] Furthermore, when backfill mining is carried out, the carbon dioxide filling pipeline is preset every 50 to 300 meters of advancement of the working face.

[0012] Further, the rock layer for grouting is selected based on porosity and permeability.

[0013] Furthermore, in step S5, carbon dioxide gas is injected into the goaf through a pipeline to form the filling material and adsorb the carbon dioxide in the working face. At the same time, the filling and carbon fixation effects are evaluated through the monitoring results of surface subsidence and carbon dioxide concentration. Among them, surface subsidence monitoring includes: monitoring the range of surface subsidence, the value of surface subsidence, the law of surface subsidence with the advancement of the working face and the stabilization time of surface subsidence.

[0014] In any of the above-mentioned methods for constructing carbon storage space by artificially reconstructing and plugging the key layer, the grouting position of the artificially reconstructing and plugging the key layer is determined by the buried depth of the grouting layer:

[0015] If the burial depth is shallow, vertical drilling is carried out from the ground to the grouting layer for grouting and plugging;

[0016] If the burial depth is deeper, inclined holes are constructed from the underground mining tunnel adjacent to the working face to the grouting layer for grouting and sealing.

[0017] Compared with the prior art, the present invention has the following significant effects:

[0018] 1. The present invention constructs an artificially reconstructed plugging key layer, and by injecting carbon dioxide into the artificially reconstructed carbon storage space, a large amount of carbon dioxide can be effectively sealed and reduced greenhouse gas emissions; at the same time, in the filling process, waste such as gangue and ash are mixed with carbon dioxide to make filling materials, which not only solves the problem of solid waste treatment in mines, but also reduces environmental pollution;

[0019] 2. In terms of safety, artificial reconstruction and sealing of key layers can control the height of gas-conducting fracture zones and reduce the degree of damage to overlying rock strata, thereby reducing the impact of stress on the mining process and improving mining safety; during the mining process, the construction of closed walls can also isolate the goaf and the working area to prevent gas from escaping to the working area, thereby protecting the health of workers; the technology of constructing carbon storage space by artificially recreating and sealing key layers is an important technical means to promote green mining in coal mines, which will help promote the upgrading and transformation of coal mining technology, further promote the development of backfill mining theory and technology, and provide valuable experience and demonstration for other similar coal mining operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a flow chart of the present invention;

[0021] Figure 2 This is a schematic diagram of the structure of the artificially recreated carbon storage space of the key layer of the present invention;

[0022] Figure 3 This is a schematic diagram of the arrangement of the gas injection pipeline for artificially recreating and plugging the key layer of the present invention. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0024] like Figure 1 The figure shows a flow chart of the method for constructing a carbon storage space for an artificially reconstructed key layer for plugging, which mainly includes the following steps: conducting geological surveys in actual operations to determine the thickness and lithology of the overlying rock layers, and determining the height of the gas-conducting fracture zone generated after the coal seam is mined by backfilling based on theoretical analysis and measured data; determining the location of the artificially reconstructed key layer for plugging and the grouting layer based on geological data and the height of the gas-conducting fracture zone; performing backfilling mining, wherein the carbon dioxide filling pipeline is preset every time the working face advances 50 to 300 meters; performing grouting on the overburden to reconstruct the key layer for plugging to form a carbon storage space; injecting carbon dioxide and other gases into the goaf through pipelines, monitoring the carbon dioxide concentration on the working face while performing negative carbon filling, and monitoring the surface rock movement on the surface to judge the effect of negative carbon filling.

[0025] In order to reduce carbon emissions from the mine and reduce further subsidence of the ground, a coal mine planned to carry out negative carbon grouting filling on the working face that was to be mined using the full caving method. The working face was 220m long, with an advancement length of about 2500m, a coal seam thickness of about 3.5m, a porosity of 40% for the overlying rock strata, and a burial depth of 800m.

[0026] The specific steps are as follows:

[0027] Step 1: Conduct geological survey to determine the thickness and lithology of the overlying rock layers, and determine the height of the gas-conducting fracture zone generated after backfill mining of the coal seam based on theoretical analysis and measured data;

[0028] First, samples were taken from the overlying rock strata on the working face to test the porosity and various mechanical properties such as strength of the rock samples. Comprehensive consideration was given to the mining depth of the working face, rock strata occurrence factors, and rock strata mechanical properties. The height of the gas-conducting fracture zone generated after backfill mining was determined to be 35m.

[0029] Step 2: Based on geological data and the height of the gas-conducting fracture zone, determine the location of the key layer for artificial reconstruction and plugging and the grouting layer;

[0030] Furthermore, the key layer for artificial reconstruction and plugging is generally located above the gas-conducting fracture zone, and the grouting layer is generally located in the abscission zone or fracture zone.

[0031] Furthermore, the grouting position of the artificially reconstructed plugging key layer is determined by the buried depth of the grouting layer:

[0032] If the burial depth is shallow, vertical drilling can be carried out from the ground to the grouting layer for grouting and plugging;

[0033] If the burial depth is deep, inclined drilling can be constructed from the underground adjacent working face recovery tunnel to the grouting layer for grouting plugging. Among them, the drilling and grouting should be blocked in time after completion to prevent carbon dioxide gas leakage.

[0034] Step 3: Carry out backfill mining, and preset the carbon dioxide filling pipeline every time the working face advances 50 to 300 meters;

[0035] During the mining process, the filling materials are transported to the interior of the goaf through pipelines or transportation equipment for filling to support the rock mass around the goaf. In addition, in order to be able to smoothly inject carbon dioxide into the working face after the mining work is completed, the carbon dioxide injection pipeline is preset every 50 to 300 meters of the working face, laying the foundation for the subsequent injection of carbon dioxide to achieve negative carbon mining.

[0036] Step 4, grouting the overburden rock to reconstruct and seal the key layer to form a carbon storage space;

[0037] The top plate is grouted. The specific ratio of the slurry is: 45% fly ash, 40% gangue, 10% cement, 2% quicklime, and 3% accelerator. The mixed materials are stirred and mixed with water to prepare a grouting filling material with a mass concentration of 82%. The fluidity and coagulation 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 key layer for plugging, such as Figure 2During 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 a porous bottom discharge conveyor, and the rapid bonding material is sprayed through a pipeline + pump.

[0038] Before artificially reconstructing and plugging the key layer, it is necessary to determine the lithology of the overburden and the grouting area. Through geological exploration, logging data analysis and other means, the lithology of the overburden and the grouting area can be preliminarily determined. The grouting rock layer generally needs to have a higher porosity and permeability, so the sandstone layer should be the main choice of grouting rock layer.

[0039] The grouting pressure is determined according to the rock mass crushing in the grouting area. When the rock mass is severely crushed, the grouting pressure should be around 0.5MPa, and when it is relatively crushed, it should be around 1MPa. When the fissures are less developed, a grouting pressure of 1-2MPa can be used. The mine is buried deep, and inclined drilling should be constructed from the underground adjacent working face recovery tunnel to the grouting layer for grouting plugging, so that the process of artificially recreating and plugging the key layer will not have a significant impact on the carbon storage space.

[0040] Step 5: inject carbon dioxide or other gases into the goaf through the carbon dioxide filling pipeline, such as Figure 3 As shown. While negative carbon filling is being performed, the carbon dioxide concentration is monitored on the working face, and the surface rock movement is monitored on the surface to determine the effect of negative carbon filling;

[0041] Carbon dioxide and other gases are injected into the goaf through pipelines to shape the filling materials and adsorb the carbon dioxide in the working face. At the same time, the filling and carbon fixation effects are evaluated through the monitoring results of surface subsidence and carbon dioxide concentration. Among them, surface subsidence monitoring includes: monitoring the scope of surface subsidence, the value of surface subsidence, the law of surface subsidence with the advancement of the working face, and the stabilization time of surface subsidence; carbon dioxide concentration monitoring: monitoring the carbon dioxide concentration of the working face. If the carbon dioxide concentration increases abnormally, it means that the sealing effect of the carbon storage space is not good, and additional grouting should be carried out by adjusting the grouting pressure, grouting position or layer.

[0042] Furthermore, in this embodiment, liquid carbon dioxide is converted into gaseous state through a water-liquid vaporizer, and then transported to a location where filling is required through a grouting pipeline. During the filling process, a suitable release position is selected according to actual needs, and carbon dioxide gas is injected into the goaf to achieve the purpose of filling and adsorbing carbon dioxide.

Claims

1. A method for constructing a carbon storage space by artificially recreating and plugging a key layer, characterized in that: The steps include: S1, conduct geological survey to determine the thickness and lithology of the overlying rock layers; S2, based on theoretical analysis and measured data, determine the height of the gas-conducting fracture zone generated after backfill mining of the coal seam; S3, based on geological data and the height of the gas-conducting fracture zone, determine the location of the key layer for artificial reconstruction and plugging and the grouting layer; S4, backfill mining is carried out, and grouting is performed on the overburden rock to reconstruct and seal the key layer to form a carbon storage space; S5, inject carbon dioxide gas into the goaf through pipelines, monitor carbon dioxide concentration on the working face while performing negative carbon filling, monitor surface rock movement on the surface, and judge the effect of negative carbon filling.

2. The method for constructing carbon storage space by artificially recreating and plugging key layers according to claim 1, characterized in that: When backfill mining is carried out, the carbon dioxide filling pipeline is preset every 50 to 300 meters of advancement of the working face.

3. The method for constructing carbon storage space by artificially recreating and plugging key layers according to claim 1, characterized in that: The rock formation for grouting is selected based on porosity and permeability.

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

5. The method for constructing carbon storage space by artificially recreating and plugging key layers according to any one of claims 1 to 4, characterized in that: The grouting position of the key layer of artificial reconstruction and plugging 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 plugging; If the burial depth is deeper, inclined holes are constructed from the underground mining tunnel adjacent to the working face to the grouting layer for grouting and sealing.

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