Gas-spontaneous combustion-dynamic disaster control method based on high-level horizontal long drill hole

Abstract

According to the gas-spontaneous combustion-dynamic disaster control method based on the high-position horizontal long drill holes, the high-position horizontal long drill holes are formed in a top plate in the mining direction, multiple purposes are achieved through one hole, and the gas extraction and filling functions are achieved; gas extraction is firstly carried out through a high-level horizontal long drill hole along with advancing of a working face, and then grouting filling is carried out through a novel sulphoaluminate cement-based double-liquid filling material according to the caving step pitch of a top plate; after the slurry is condensed, a stable filling body is formed, further development of a layered top fracture field is inhibited, broken coal and rock mass are bonded to provide support for a top plate above a coal seam, and spontaneous combustion of residual coal and top plate disasters are reduced; and cyclic operation of the gas extraction system and the filling and grouting system is ensured in the propelling process. Gas control, fire prevention and extinguishing and roof control are effectively integrated, the drilling work amount is greatly reduced, the disaster control cost is reduced, mine water resources and solid waste are utilized, and the safety and environmental friendliness of mine mining are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of safe coal seam mining technology, and in particular to a method for controlling gas-spontaneous combustion-dynamic disasters based on high-level horizontal long boreholes. Background Technology

[0002] In the coal mining sector, thick coal seams possess abundant reserves, and their efficient mining is crucial for meeting energy demands. Thick coal seam layered fully mechanized longwall mining, as an important mining method, is widely used in many coal mines due to its high resource recovery rate and production efficiency. However, this mining method causes significant disturbance to the strata during practical application. During thick coal seam layered fully mechanized longwall mining, the lower layers of the coal seam fracture under pressure relief. This process causes a large amount of gas originally contained within the coal seam to rapidly erupt. For high-gas coal mines, to effectively prevent mine disasters caused by excessive gas levels at the working face, relevant regulations explicitly require the installation of gas drainage systems at the working face. Through gas drainage systems, the gas emanating from the coal seam can be extracted and utilized or safely discharged, thereby reducing the gas concentration at the working face and maintaining it within a safe range. However, in actual gas drainage processes, many challenges are encountered. Due to the wide range of gas pressure relief, a large number of drainage boreholes need to be deployed to achieve the ideal drainage effect. The construction of numerous gas drainage boreholes not only requires a significant investment of manpower and resources, increasing mining costs, but also has a long construction period, impacting the normal production schedule of coal mines. Furthermore, quality control during borehole construction is challenging; poor drilling quality can lead to low gas drainage efficiency, failing to effectively reduce gas concentration at the working face, and still posing a safety hazard of excessive gas levels. Simultaneously, large-scale roof overhangs during coal mining can lead to serious safety accidents, especially in the layered fully mechanized longwall mining of steeply inclined thick coal seams, where the collapse pattern of the roof strata during working face mining is unclear. Without appropriate measures, sudden large-scale roof collapses may occur, causing major accidents. In conclusion, the gas emission and roof management issues encountered in the layered fully mechanized longwall mining of thick coal seams severely restrict the safe and efficient production of coal mines. Summary of the Invention

[0003] In view of the problems existing in the prior art, the present invention aims to provide a gas-spontaneous combustion-dynamic disaster control method based on high-level horizontal long boreholes, which can reduce the gas concentration in the working face, provide support for the coal seam roof, and suppress spontaneous combustion of residual coal in the goaf.

[0004] To achieve the above objectives, this invention proposes a gas-spontaneous combustion-dynamic disaster control method based on high-level horizontal long boreholes, comprising the following steps: S1. At the location of the roof above the working face in the vertical direction, select a roof rock layer that can collapse with the working face and has an intact structure after the collapse, and arrange a high-level horizontal long borehole as a gas extraction pipeline for the working face, and ensure that the end of the borehole is located in the gas-rich area of ​​the goaf. S2. Arrange the gas extraction system and the filling grouting system. First, connect the extraction pipeline of the gas extraction system to the high-level horizontal long borehole of the working face. As the working face advances, gas extraction is carried out through the high-level horizontal long borehole to reduce the gas concentration in the goaf. S3. When the gas concentration in the goaf decreases to a safe level, gas extraction at the working face is stopped, and the filling grouting system is switched to operation. The grouting pipeline of the filling grouting system is connected to the high-level horizontal long borehole of the working face. A filling step distance that can achieve the gradual collapse of the roof is selected. Grouting is carried out using a new type of sulfoaluminate cement-based dual-liquid filling material. The new type of sulfoaluminate cement-based dual-liquid filling material uses sulfoaluminate cement as the base material and is compounded with water-reducing agent, water glass and fly ash. The mass ratio of sulfoaluminate cement, activator, sodium water glass and water-reducing agent is 7~9:1~3:5:0.1. The setting time and compressive strength of the dual-liquid slurry can be adjusted within the range of 4.1~140min and 3.78~14.32MPa. The filling slurry flows out from the end of the high-level horizontal long borehole and forms a stable filling body along the void network to inhibit the further development of the fracture field at the top of the layer and to bond the broken coal and rock mass to provide support for the roof above the coal seam. S4. When the gas concentration in the goaf rises to a level exceeding the safety value, restart the gas drainage system and switch the drainage pipeline to a high-level horizontal long borehole in the working face for gas drainage. S5, repeat steps S2-S4 to ensure the cyclical operation of the gas extraction system and the filling grouting system.

[0005] In the above scheme: the diameter of the high-level horizontal long borehole is ≥100mm to ensure gas extraction and grouting efficiency.

[0006] In the above scheme: after each grouting is completed, the high-level horizontal long borehole is flushed with water to ensure that the high-level horizontal long borehole is clean and unblocked.

[0007] In the above scheme: the gas extraction system includes a gas extraction pump station and extraction pipelines; the filling grouting system includes a filling grouting station and grouting pipelines. The gas extraction pump station is located on the surface, and the filling grouting station is located underground. The raw materials for grouting are transported from the surface to the underground. The water source for grouting and flushing the high-level horizontal long borehole is mine water stored in an underground water tank. This scheme is convenient to implement, and the use of mine water for flushing the high-level horizontal long borehole helps save costs.

[0008] In the above scheme, the grouting parameters of the filling grouting system are: pumping pressure 1.5-4.0 MPa, flow rate 200-500 L / min. The specific grouting parameters can be set according to the actual production situation.

[0009] In the above scheme, the mass ratio of sulfoaluminate cement, activator, sodium silicate, and water-reducing agent is 9:1:5:0.1 or 7:3:5:0.1. This ratio provides material flowability and solidification characteristics that better meet the performance requirements of backfill materials in the complex geostress environment of coal mining areas. Specifically, the material ratio can be adjusted according to the collapse of the coal and rock mass in the goaf, thereby controlling the material flowability and solidification characteristics to meet the performance requirements of backfill materials in the complex geostress environment of coal mining areas.

[0010] In the above scheme: for close-range coal seams or steeply inclined coal seams, water exploration and drainage operations are carried out on the roof in advance before the lower layer mining. Excess water from the upper layer operation is drained and discharged to the nearest water tank for use in slurry preparation and high-level horizontal long borehole flushing. This can ensure construction safety and facilitate subsequent flushing operations.

[0011] The beneficial effects of this invention are: 1. Horizontal long boreholes with "one hole, multiple uses" reduce the amount of drilling work, greatly reducing the manpower and costs required for drilling, and simultaneously solving three major problems: gas extraction, spontaneous combustion prevention, and roof control. One-time drilling avoids frequent drilling required for extraction and backfilling, ensuring normal and continuous production at the working face. 2. Based on sulfoaluminate cement, a new type of cement-based dual-liquid backfill material was prepared by combining water-reducing agents, water glass, and fly ash solid waste materials. This material is optimized for the complex geological stress environment induced by coal mining and the special characteristics of goaf backfilling, with optimized fluidity, setting time, and compressive strength, aiming to improve the long-term stability and engineering applicability of goaf sealing. The setting time and compressive strength of the dual-liquid slurry can be adjusted within the range of 4.1~140 min and 3.78~14.32 MPa, meeting the material performance requirements of goaf backfilling projects. 3. The composition of the backfill material can weaken acidic mine water, effectively preventing equipment corrosion and being environmentally friendly. Furthermore, the continuous load-bearing structure formed by the filling body, with dynamic grouting matching the collapse step of the roof, reduces the suspended roof area by more than 70%, completely avoids dynamic disasters, reduces the area of ​​surface subsidence and collapse, and reduces the cost of environmental remediation and restoration. Attached Figure Description

[0012] Figure 1 This is an application diagram of the present invention (the left side is a longitudinal cross-sectional diagram of the present invention applied to the layered fully mechanized longwall mining process of steeply inclined thick coal seams, and the right side is a transverse cross-sectional diagram of the present invention applied to the layered fully mechanized longwall mining process of steeply inclined thick coal seams). Detailed Implementation

[0013] like Figure 1 As shown, a gas-spontaneous combustion-dynamic disaster control method based on high-level horizontal long boreholes mainly consists of the following steps: S1. At the location of the roof 2 above the working face in the vertical direction, select a roof rock stratum that can collapse with the working face and has an intact structure after the collapse (according to the numerical simulation of the collapse law of the roof and borehole), arrange a high-level horizontal long borehole 3 as a gas extraction pipeline for the working face, and ensure that the end of the borehole 4 is located in the gas-rich area of ​​the goaf 5.

[0014] S2. Arrange the gas extraction system and the filling grouting system. First, connect the extraction pipeline of the gas extraction system to the high-level horizontal long borehole 3 of the working face. As the working face advances, the coal and rock collapses in the rear to form the goaf 5, and a large amount of gas is released. Gas extraction is carried out through the high-level horizontal long borehole 3 to reduce the gas concentration in the goaf 5.

[0015] S3. When the gas concentration in the goaf 5 decreases to a safe level, stop gas extraction at the working face and switch to the filling and grouting system. Connect the grouting pipeline of the filling and grouting system to the high-level horizontal long borehole 3 at the working face. Select a filling step distance that can achieve the gradual collapse of the roof 2 (specifically based on the collapse step distance of the roof 2, the height of the fracture development, the material diffusion radius, and the working face advance speed, analyze the support effect of different filling step distances on the roof 2 and the coverage effect on the goaf 5 through experimental research and numerical simulation, and select a filling step distance that can achieve the gradual collapse of the roof 2 and has a strong support effect). Use the new sulfoaluminate cement-based dual-liquid filling material 6 for grouting and filling.

[0016] The novel sulfoaluminate cement-based two-component filling material 6 uses sulfoaluminate cement as the base material and is compounded with alkali activator, sodium water glass and water-reducing agent. The mass ratio of sulfoaluminate cement, activator, sodium water glass and water-reducing agent is 7~9:1~3:5:0.1. The setting time and compressive strength of the two-component slurry can be adjusted within the range of 4.1~140min and 3.78~14.32MPa.

[0017] The filling grout flows out from the end 4 of the high-level horizontal long drill 3 and forms a stable filling body along the void network to inhibit the further development of the fracture field at the top of the layer. The filling body binds the fractured coal and rock mass and provides support to the roof 2 above the coal seam 1. The filling body reduces air leakage from the working face and surface to the goaf 5, covers the fractured coal and rock mass, and effectively inhibits the spontaneous combustion of residual coal after multi-layer mining. Specifically, the filling body fully wraps the collapsed coal and the fractured roof rock mass, provides support to the roof 2, and seals the air leakage channels in the goaf, reducing the air leakage problem in the goaf 5.

[0018] S4. When the gas concentration in the goaf 5 rises to a level exceeding the safety value, restart the gas drainage system and switch the drainage pipeline to the high-level horizontal long borehole 3 of the working face for gas drainage.

[0019] As the working face advances, the roof slab 2 collapses, and the high-level horizontal long borehole 3 breaks. Its end position moves with the working face, ensuring that the high-level horizontal long borehole 3 can continuously carry out gas extraction and grouting operations.

[0020] S5, repeat steps S2-S4 to ensure the cyclical operation of the gas extraction system and the filling grouting system.

[0021] Ideally, the diameter of the high-level horizontal long borehole 3 should be ≥100mm to ensure gas extraction and grouting efficiency.

[0022] Ideally, after each grouting operation, the high-level horizontal long borehole 3 should be flushed with water to ensure that it is clean and free of blockages.

[0023] Ideally, the gas extraction system includes a gas extraction pump station and extraction pipelines, while the filling and grouting system includes a filling and grouting station and grouting pipelines. The gas extraction pump station is located on the surface, and the filling and grouting station is located underground. The raw materials for the filling and grouting station are transported from the surface to the underground. The water source for grouting and flushing the high-level horizontal long borehole 3 is mine water stored in an underground water tank. This arrangement is convenient, and using mine water to flush the high-level horizontal long borehole 3 helps save costs.

[0024] Ideally, the grouting parameters of the filling grouting system should be: pumping pressure 1.5-4.0 MPa, flow rate 200-500 L / min. The specific grouting parameters can be set according to the actual production situation.

[0025] Ideally, the mass ratio of sulfoaluminate cement, activator, sodium silicate, and water-reducing agent should be 9:1:5:0.1 or 7:3:5:0.1. This ratio ensures that the material's fluidity, solidification properties, and compressive strength fully meet the performance requirements of backfill materials in the complex geostress environment of coal mining areas. Specifically, the material ratio can be adjusted according to the collapse conditions of the coal and rock mass in the goaf, thereby controlling the material's fluidity and solidification properties to meet the performance requirements of backfill materials in the complex geostress environment of coal mining areas.

[0026] Ideally, for close-range or steeply inclined coal seams, water exploration and drainage operations should be carried out on the roof 2 before the lower layer mining. Excess water from the upper layer operation should be drained and discharged into the nearest water tank for use in slurry preparation and high-level horizontal long borehole flushing. This can ensure construction safety and facilitate subsequent flushing operations.

Claims

1. A method for controlling gas-spontaneous combustion-dynamic disasters based on high-level horizontal long boreholes, characterized in that, Includes the following steps: S1. At the position of the roof (2) above the working face in the vertical direction, select the roof rock layer that can collapse with the working face and has a complete structure after the collapse, arrange the high-level horizontal long borehole (3) as the working face gas extraction pipeline, and ensure that the end of the borehole (4) is located in the gas-rich area of ​​the goaf (5). S2. Arrange the gas extraction system and the filling grouting system. First, connect the extraction pipeline of the gas extraction system to the high-level horizontal long borehole (3) of the working face. As the working face advances, gas extraction is carried out through the high-level horizontal long borehole (3) to reduce the gas concentration in the goaf (5). S3. When the gas concentration in the goaf (5) drops to a safe level, stop gas extraction at the working face and switch to the filling grouting system. Connect the grouting pipeline of the filling grouting system to the high-level horizontal long borehole (3) at the working face. Select a filling step distance that can achieve the gradual collapse of the roof (2). Use a new type of sulfoaluminate cement-based double liquid filling material (6) for grouting. The new type of sulfoaluminate cement-based double liquid filling material (6) is based on sulfoaluminate cement and compounded with alkali fly ash, sodium water glass and polycarboxylate high-efficiency water-reducing agent. The mass ratio of sulfoaluminate cement, activator, sodium water glass and water-reducing agent is 7~9:1~3:5:0.

1. The filling grout flows out from the end (4) of the high-level horizontal long borehole (3) and forms a stable filling body along the void network to inhibit the further development of the fracture field at the top of the layer and bond the broken coal and rock mass to provide support for the roof (2) above the coal seam (1). S4. When the gas concentration in the goaf (5) rises to a level exceeding the safety value, restart the gas extraction system and switch the extraction pipeline to the high-level horizontal long borehole (3) of the working face for gas extraction. S5, repeat steps S2-S4 to ensure the cyclical operation of the gas extraction system and the filling grouting system.

2. The gas-spontaneous combustion-dynamic disaster control method based on high-level horizontal long boreholes according to claim 1, characterized in that: The diameter of the high-level horizontal long borehole (3) is ≥100mm.

3. The gas-spontaneous combustion-dynamic disaster control method based on high-level horizontal long boreholes according to claim 1, characterized in that: After each grouting is completed, the high-level horizontal long borehole is flushed with water (3).

4. The gas-spontaneous combustion-dynamic disaster control method based on high-level horizontal long boreholes according to claim 3, characterized in that: The gas extraction system includes a gas extraction pump station and extraction pipelines. The filling and grouting system includes a filling and grouting station and grouting pipelines. The gas extraction pump station is located on the ground, and the filling and grouting station is located underground. The raw materials for grouting are transported from the surface to the underground. The water source for grouting and flushing the high-level horizontal long borehole (3) is mine water stored in the underground water tank.

5. The gas-spontaneous combustion-dynamic disaster control method based on high-level horizontal long boreholes according to claim 4, characterized in that, The grouting parameters of the filling grouting system are: pumping pressure 1.5-4.0 MPa, flow rate 200-500 L / min.

6. The gas-spontaneous combustion-dynamic disaster control method based on high-level horizontal long boreholes according to claim 1, characterized in that: The mass ratio of the sulfoaluminate cement, activator, sodium silicate, and water-reducing agent is 9:1:5:0.1 or 7:3:5:0.

1.

7. The gas-spontaneous combustion-dynamic disaster control method based on high-level horizontal long boreholes according to claim 5, characterized in that: For close-range coal seams or steeply inclined coal seams, water exploration and drainage operations are carried out on the roof (2) before the lower layer mining, and excess water from the upper layer operation is drained and discharged to the nearest water tank for use in slurry preparation and high-level horizontal long borehole flushing.

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