A method for entering a room-and-pillar goaf to construct a fully mechanized mining face tunnel

Abstract

The present invention discloses a method for constructing a fully mechanized mining face tunnel in a room-and-pillar goaf. The method comprises the following steps: (1) determining the position of the fully mechanized mining face tunnel and the area to be filled; (2) constructing from the opening position of the transport chute: 1) directional drilling is performed along the roof outside the area in the direction of the transport chute to be arranged, and then the chute is passed through the roof to communicate with the room-and-pillar goaf; 2) a flexible filling pipe is inserted into the directional drilled hole to fill the empty area below the drilled hole with slurry; 3) after the strength of the filling body reaches the design requirements, excavation is carried out in the filling body in the direction of the transport chute; while excavating, air is supplied from the rear; when excavating to the edge of the filling body area, excavation is stopped; along the predetermined route of the transport chute, the cut-eye, and the return air chute, 1)-3) is repeated to construct forward until the opening position of the return air chute is reached. The present invention can solve the problem of turbulent airflow and difficulty in entering the room-and-pillar goaf, thereby realizing the recovery of the room-and-pillar coal pillars left behind by arranging the fully mechanized mining face.

Description

Technical Field

[0001] The invention belongs to the field of mine filling mining and goaf management, and particularly relates to a construction process for recovering coal pillar resources left in room-and-pillar goafs. Background Art

[0002] Outdated production processes, designed to reduce production costs, rely on excavation instead of mining, without distinguishing between excavation and mining. Years of mining have left behind numerous room-and-pillar goafs, which pose numerous hidden dangers to the local area. 1) A significant waste of high-quality coal resources. The room-and-pillar mining method only recovers 30% to 50% of the coal, and in some small coal mines, the recovery rate is even less than 30%. This leaves a large amount of high-quality, residual coal pillars underground, resulting in a significant waste of coal resources. 2) The risk of large-scale roof collapse. Over time, the coal pillars undergo fluidization, triggering large-scale, sudden roof collapses and causing earthquakes, posing safety hazards to both above and below ground. 3) The risk of spontaneous combustion in the goaf. 4) The destruction of groundwater and the resulting soil erosion. Previously used coal pillar recovery technologies suffer from issues such as an inability to address ventilation issues, difficulty in roof management, the tendency of residual coal pillars to suddenly become unstable, and low recovery efficiency. Consequently, there is a lack of safe and efficient recovery methods.

[0003] The applicant has invented a method for recovering coal pillars left behind in room-and-pillar goafs. The method involves first filling the room-and-pillar goaf with a cemented backfill containing coal as the aggregate, then arranging a longwall working face, and finally recovering the cemented backfill containing coal as the aggregate along with the room-and-pillar coal pillars. This mining method is simple, mature, safe, and high-yield. Furthermore, the cemented backfill containing coal as the aggregate has no effect on the quality of the mined room-and-pillar coal pillars. Furthermore, the coal is easily accessible, low-cost, and recyclable. This method provides an effective way to safely and efficiently recover room-and-pillar coal pillars.

[0004] However, the room-and-pillar goaf has existed for many years. The oxygen content in the area is low, and direct entry by construction workers will threaten their lives. If ventilation is carried out first, the numerous coal pillars in the goaf are intertwined, the air path is disordered, and it does not comply with relevant regulations. Therefore, the problem of entering the room-and-pillar goaf to construct the comprehensive mining working face tunnel has not been solved, making it impossible to arrange the comprehensive mining working face drift and cutting eye, and it is also impossible to achieve comprehensive mining to recover the coal pillars left over from the room-and-pillar goaf. Summary of the Invention

[0005] In view of the difficulty in entering a room-and-pillar goaf to construct a fully mechanized mining face tunnel, the present invention aims to provide a method for entering a room-and-pillar goaf to construct a fully mechanized mining face tunnel.

[0006] The present invention provides a method for entering a room-and-pillar goaf to construct a fully mechanized mining face tunnel, comprising the following steps:

[0007] (1) Determining the location of a fully mechanized mining face tunnel to be arranged in a room-and-pillar goaf, wherein the fully mechanized mining face tunnel includes a transport chute, a cut-hole, and a return air chute, wherein the transport chute and the return air chute are connected by the cut-hole; determining an area to be filled, wherein the area to be filled covers the transport chute, the cut-hole, and the return air chute to be arranged;

[0008] (2) The opening position of the transport chute outside the room-and-pillar goaf shall be constructed according to the following steps 1)-3):

[0009] 1) Directional drilling is carried out along the roof outside the area in the direction of the planned transport chute. After reaching the designated location, the hole is drilled downward through the roof to connect with the room-and-pillar goaf;

[0010] 2) inserting a flexible filling pipe into the directional drilled hole, and filling the empty area below the drilled hole with slurry through the flexible filling pipe; stopping the filling when the flowing slurry reaches the top and the pipe pressure reaches a set value;

[0011] 3) After the filling body strength reaches the design requirements, excavation is carried out in the filling body along the transport channel direction; while excavation, air is supplied from the rear, and the tunnel roof and both sides are supported; excavation is stopped when the excavation reaches the edge of the filling body area;

[0012] Along the predetermined route of the transport chute, cut-eye, and return air chute, the cycle of steps 1)-3) is carried out forward until the opening position of the return air chute is reached. At this point, the transport chute, cut-eye, and return air chute are excavated through, completing the construction of the fully mechanized mining working face tunnel.

[0013] Furthermore, in step (1), the transport chute and the return air chute are parallel, and the cut eye is perpendicular to the transport chute and the return air chute;

[0014] The fully mechanized mining working face is arranged in combination with the size of the area and relevant regulations and specifications. Specifically, the fully mechanized mining working face can be 1 to 2 km long, 100 to 300 m wide, the tunnel width can be 4 to 6 m, and the tunnel height can be 3 to 5 m.

[0015] Furthermore, in step (2), the diameter of the directional drilling hole in the process 1) can be 200 to 300 mm, and the final hole position is located in the middle of the area to be filled this time.

[0016] Furthermore, in step (2), the flexible filling pipe in the process 2) can be a rubber hose, and the compressive strength can be 2 MPa.

[0017] Furthermore, in step (2), the slurry is prepared at the filling station and transported through a pipeline by means of a pump pressure. After exiting the pipeline, the slurry flows in the goaf and gradually solidifies into a solidified filling body. On the one hand, tunneling in the dense filling body can form a local fan ventilation that meets the standards. On the other hand, the filling bodies on both sides can maintain the tunnel formed by tunneling.

[0018] The range of the filling body formed is related to the flow radius of the slurry. The slurry in the process 2) adopts paste material and is transported through a pipeline. It is initially in a slurry state and flows in the goaf, and then gradually solidifies into a consolidated body; the tunnel range is filled with the paste, laying the foundation for tunnel excavation; the paste flow radius is related to the concentration ratio, and can be specifically 20 to 40 meters.

[0019] Furthermore, in step (2), a filling system is started to implement the filling operation. The filling system is located at the filling station and is composed of aggregate crushing, raw material weighing and conveying, stirring, pumping, pipe valves and other systems to achieve the preparation of filling slurry;

[0020] The paste filling material should meet the requirements of transportation during slurry and strength after solidification. The slump of the filling slurry in step 2) should be between 18 and 28 cm, and the uniaxial compressive strength 28 days after solidification should be between 2 and 6 MPa.

[0021] Furthermore, in step (2), the contact width between the filling body and the top plate is not less than 40m.

[0022] Furthermore, in step (2), a roadheader or a continuous coal miner is used to excavate the tunnel in step 3), with a mining height of 3 to 5 m and a mining width of 4 to 6 m.

[0023] Furthermore, in step (2), the rear air supply in the process 3) adopts a local ventilator or a hanging air duct to supply air to the tunnel being excavated and the tunnel that has been excavated; the air supply adopts a forced-in ventilation method.

[0024] The present invention further provides a method for recovering coal pillars left in a room-and-pillar goaf, comprising the steps of using any of the above methods to enter the room-and-pillar goaf and construct a fully mechanized mining face tunnel.

[0025] The present invention has the following beneficial effects:

[0026] This invention provides a method for constructing a fully mechanized mining face tunnel within a room-and-pillar goaf. The method involves sequentially directional drilling → backfilling → tunneling (ventilation and support) → directional drilling → backfilling → tunneling (ventilation and support), achieving safe construction of fully mechanized mining face tunnels within a room-and-pillar goaf. This method addresses the issues of turbulent airflow and difficulty accessing room-and-pillar goafs, thereby addressing the significant challenge of recovering coal pillars left behind by deploying a fully mechanized mining face. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is an illustration of the technical background of this application, "filling first and then arranging the fully mechanized mining working face to recover the room-pillar type remaining coal pillars."

[0028] Figure 1The marks are as follows: 1-remaining coal pillar; 2-filling body; 3-transport chute; 4-cutting eye; 5-return air chute; 6-support; 7-coal mining machine; 8-fully mechanized mining goaf.

[0029] Figure 2 It is a schematic diagram of the proposed layout of the transport chute, cutting eye, return air chute and initial filling plane of the fully mechanized mining face.

[0030] Figure 2 The marks in the figure are as follows: 2-filling body; 10-filling pipe; 13-filling station; 16-expected filling range boundary; 17-transport chute; 18-cutting eye; 19-return air chute.

[0031] Figure 3 for Figure 2 Middle A-A section.

[0032] Figure 3 The marks are as follows: 2-filling body; 10-filling pipe; 20-drill hole; 21-coal seam roof; 22-coal seam floor; 23-outside the room-and-pillar goaf; 24-isolation wall.

[0033] Figure 4 for Figure 2 Middle B-B section.

[0034] Figure 4 The marks are as follows: 2-filling body; 20-directional drilling hole; 21-coal seam roof; 22-coal seam floor.

[0035] Figure 5 It is a schematic diagram of the proposed layout of the transport drift, cutting eye, return air drift filling and excavation plan for the fully mechanized mining face.

[0036] Figure 5 The marks in the figure are as follows: 2-filling body; 9-tunnel formed by excavation; 10-filling pipe; 11-air duct; 12-tunneling machine; 13-filling station; 14-upper circulation filling body; 15-boundary of the filled area; 16-boundary of the expected filling range; 17-transport chute; 18-cutting eye; 19-return air chute.

[0037] Figure 6 for Figure 5 Middle C-C section.

[0038] 2-filling body; 10-filling pipe; 11-air duct; 12-tunnel; 14-upper circulation filling body; 20-directional drilling; 21-coal seam roof; 22-coal seam floor.

[0039] Figure 7 for Figure 5 Middle D-D section.

[0040] 2-filling body; 21-coal seam roof; 22-coal seam floor. DETAILED DESCRIPTION

[0041] Figure 1 This diagram illustrates a method for recovering the remaining coal pillar 1 by first filling the room-and-pillar goaf and then deploying a longwall working face. After the room-and-pillar goaf is filled (filling 2), the fully mechanized face's haulage chute 3, cutter eye 4, and return air chute 5 are successively excavated. Equipment such as supports 6 and shearers 7 are deployed at the working face. As shearers 7 cut the coal 1 and filling 2, the remaining coal pillar 1 is recovered. The working face then advances, forming a fully mechanized goaf 8 behind it.

[0042] To fill a room-and-pillar goaf, tunneling must first establish a fully mechanized face haulage chute 3, a cut-hole 4, and a return air chute 5. This presupposes access to the room-and-pillar goaf for construction. However, goafs are often formed over a long period of time, with minimal airflow, making it difficult for personnel to access these areas. Furthermore, ventilation, due to the numerous interspaced coal pillars within a room-and-pillar goaf, creates complex and chaotic airflow paths that do not meet regulatory requirements. Therefore, access is a significant challenge.

[0043] See also Figure 2-Figure 6 The present invention provides a method for entering a room-and-pillar goaf to construct a fully mechanized mining face tunnel, comprising the following steps:

[0044] Step 1: First determine the location of the fully mechanized mining face tunnel to be arranged. The fully mechanized mining face tunnel includes the transport chute, cut-hole and return air chute. The transport chute and return air chute are connected by the cut-hole. Then determine the area to be filled. The area to be filled covers the transport chute, cut-hole and return air chute to be arranged. Figure 2 For example, in order to form a fully mechanized mining face, the transportation drift 17 to be excavated, the cut hole 18 to be excavated, and the return air drift 19 to be excavated are shown in the figure. The expected filling range boundary 16 is as follows: Figure 2 shown.

[0045] Step 2: Filling operation Figure 3 As shown in the cross-sectional view, 21 is the coal seam roof and 22 is the coal seam floor. Starting from the opening of the transport chute 17, a directional borehole 20 is constructed along the roof from the outside of the room-and-pillar goaf 23 through the isolation wall 24 to the location where the transport chute 17 is to be located. After reaching the designated location, the borehole is drilled downward to connect with the room-and-pillar goaf. A flexible filling pipe 10 is inserted into the directional borehole 20. Then, slurry is prepared and pumped at the filling station 13. As the filling slurry flows and gradually solidifies, a filling body 2 is formed. Ensure that the contact width W between the filling body 2 and the roof 21 is not less than 40m. Figure 4 shown.

[0046] Step 3: After the filling body reaches the designed strength, the tunnel excavation operation is carried out. The opening position of the transport drift is relatively short, the operation is relatively special, and lacks representativeness, so the conventional section is used as an example. Figure 5 and Figure 6 As shown, a tunnel boring machine 12 is used to excavate along the planned transport chute 17 towards the room-and-pillar goaf. A wind tunnel 11 is set up at the rear to provide forced-in ventilation and air supply to the tunnel boring head. Figure 7 As shown. When the backfill is not connected to the top, excavation is stopped. A directional drill hole 20 is then drilled forward in the roof. Then, a filling pipe 10 is inserted and filled to form the backfill 2, which is then covered with the circulating backfill 14. Filling and excavation are repeated alternately until the excavation of the transport chute 17, cut-eye 18, and auxiliary transport chute 19 is completed, thereby demarcating the fully mechanized mining face within the room-and-pillar goaf.

[0047] The method provided by the present invention comprises the following steps: firstly filling the position of the planned tunnel (including the transport chute, cut-eye and return air chute), forming a certain diffusion range of the filling slurry, and then excavating the tunnel in the filling body after the filling body reaches the strength requirement. By first filling and then excavating, the transport chute, cut-eye and auxiliary transport chute of the comprehensive mining face are excavated, thereby forming a comprehensive mining face, avoiding the problem of chaotic airflow in the room-and-pillar goaf and inability to enter for construction.

[0048] The following describes a method for recovering coal pillars left behind in room-and-pillar goafs, as provided by the present invention, through specific examples. The experimental methods used in the following examples are conventional methods unless otherwise noted. Materials and reagents used are commercially available unless otherwise specified.

[0049] Example 1

[0050] A room-and-pillar goaf in a certain mine has a depth of H = 410m, a mined thickness of M = 3m, a mining width of L = 6m, and a residual pillar width of B = 8m. The planned fully mechanized mining face is 100m wide (i.e., the length of the cut) and 1000m long (i.e., the length of the haulage and auxiliary haulage chute).

[0051] First, a 240mm diameter directional drill hole was drilled in the roof of the room-and-pillar goaf, at the opening of the transport tunnel. At the 20m mark, the hole connected to the room-and-pillar goaf. A 180mm Φ filling pipe (rubber hose with a compressive strength of 2MPa) was inserted, and the slurry prepared at the filling station was used for filling. The slurry diffusion radius was 25m (the slurry slump was 21cm), and the fill width at the top was W = 46m. After 28 days, the fill strength reached the designed 3MPa. Excavation was resumed using a roadheader, followed by a wind tunnel. At 25m, a cavity appeared at the top of the fill, and excavation was halted. A second directional drill hole of the same size and length was drilled in the roof, and filling continued. This cycle was repeated 40 times, each for filling and excavation, before excavation of the transport tunnel was completed. The forward direction then turns 90° left, and directional drilling, backfilling, and tunneling are performed in the designated cut-hole direction. After four cycles of each, cut-hole tunneling is complete. The forward direction then turns 90° left, and directional drilling, backfilling, and tunneling are performed in the designated auxiliary haulage chute direction. After 40 cycles of each, auxiliary haulage chute tunneling is complete. At this point, tunneling of the fully mechanized mining face is complete, and production is ready for the installation of fully mechanized mining supports, shearers, and other equipment.

[0052] Example 2

[0053] A room-and-pillar goaf in a certain mine has a depth of H = 200m, a mined thickness of M = 4m, a mined width of L = 8m, and a residual pillar width of B = 10m. The planned fully mechanized mining face is 150m wide (i.e., the length of the cut) and 1500m long (i.e., the length of the haulage and auxiliary haulage chute).

[0054] First, a 280mm diameter directional drill hole was drilled in the roof of the room-and-pillar goaf, at the opening of the transport tunnel. At the 25m mark, the hole opened to connect with the room-and-pillar goaf. A 200mm Φ filling pipe (rubber hose with a compressive strength of 2MPa) was inserted, and the slurry prepared at the filling station was used for filling. The slurry diffusion radius was 30m (the slurry slump was 24cm), and the fill width at the top was W = 52m. After 28 days, the fill strength reached the designed 4MPa. Excavation was resumed using a roadheader, followed by a wind tunnel. At 30m, a cavity appeared at the top of the fill, and excavation was halted. A second directional drill hole of the same size and length was drilled in the roof, and filling continued. This cycle was repeated 50 times, each for filling and excavation, before excavation of the transport tunnel was completed. The forward direction then turns 90° left, and directional drilling, backfilling, and tunneling are performed in the designated cut-hole direction. After five cycles of each, cut-hole tunneling is complete. The forward direction then turns 90° left, and directional drilling, backfilling, and tunneling are performed in the designated auxiliary haulage chute direction. After 50 cycles of each, the auxiliary haulage chute is complete. At this point, tunneling of the fully mechanized mining face is complete, and production is ready for the installation of fully mechanized mining supports, shearers, and other equipment.

[0055] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for entering a room-and-pillar goaf to construct a fully mechanized mining face roadway, comprising the following steps: (1) Determine the location of a fully mechanized mining face tunnel to be arranged in a room-and-pillar goaf, wherein the fully mechanized mining face tunnel includes a transport chute, a cut-hole, and a return air chute, and the transport chute and the return air chute are connected by the cut-hole; determine the area to be filled, wherein the area to be filled covers the transport chute, the cut-hole, and the return air chute to be arranged; In step (1), the transport chute and the return air chute are parallel, and the cut eye is perpendicular to the transport chute and the return air chute; The fully mechanized mining working face has a length of 1 to 2 km, a width of 100 to 300 m, a tunnel width of 4 to 6 m, and a tunnel height of 3 to 5 m; (2) The opening position of the transport chute outside the room-and-pillar goaf shall be constructed according to the following steps 1)-3): 1) Directional drilling is carried out along the roof outside the area in the direction of the planned transport chute. After reaching the designated location, the hole is drilled downward through the roof to connect with the room-and-pillar goaf; 2) inserting a flexible filling pipe into the directional drilled hole, and filling the empty area below the drilled hole with slurry through the flexible filling pipe; stopping the filling when the flowing slurry reaches the top and the pipe pressure reaches a set value; 3) After the filling body strength reaches the design requirements, excavation is carried out in the filling body along the transport channel direction; while excavation, air is supplied from the rear, and the tunnel roof and both sides are supported; excavation is stopped when the excavation reaches the edge of the filling body area; Along the predetermined route of the transport chute, cut-eye, and return air chute, the cycle of steps 1)-3) is carried out forward until the opening position of the return air chute is reached. At this point, the transport chute, cut-eye, and return air chute are excavated through, completing the construction of the fully mechanized mining working face tunnel.

2. The method according to claim 1, wherein: In step (2), the diameter of the directional drilling hole in the process 1) is 200 to 300 mm, and the final hole position is located in the middle of the area to be filled.

3. The method according to any one of claims 1 to 2, characterized in that: In step (2), the flexible filling pipe in the process 2) is a rubber hose with a compressive strength of 2 MPa.

4. The method according to any one of claims 1 to 2, characterized in that: In step (2), the slurry in the process 2) is made of paste material, and the flow radius of the paste slurry is 20 to 40 m.

5. The method according to any one of claims 1 to 2, characterized in that: In step (2), the slump of the filling slurry in the process 2) is 18 to 28 cm, and the uniaxial compressive strength 28 days after solidification is 2 to 6 MPa.

6. The method according to any one of claims 1-2, characterized in that: In step (2), the contact width between the filling body and the top plate is not less than 40m.

7. The method according to any one of claims 1-2, characterized in that: In step (2), a roadheader or a continuous coal miner is used to excavate the tunnel in step 3), with a mining height of 3 to 5 m and a mining width of 4 to 6 m.

8. The method according to any one of claims 1-2, characterized in that: In step (2), the rear air supply in the process 3) adopts a local ventilator or a hanging air duct; the air supply adopts a forced-in ventilation method.

9. A method for recovering coal pillars left in a room-and-pillar goaf, comprising the steps of entering the room-and-pillar goaf and constructing a fully mechanized mining face tunnel using the method according to any one of claims 1 to 8.

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