A method for reducing coal gangue emissions underground by replenishing goaf areas during mining.

Abstract

This invention relates to a method for replenishing goaf during underground coal gangue mining, comprising the following steps: a. excavating a return airway in the upper part of the working face and excavating a transport roadway and an auxiliary roadway in the lower part of the working face; b. advancing the working face mining area and drilling directional grouting boreholes along the dip from the auxiliary roadway into the roof above the working face, the horizontal section of the directional grouting boreholes being located within the roof strata above the working face; inserting a grouting pipe with an outer diameter matching the diameter of the exposed borehole into the directional grouting borehole; c. mining the working face, and when a grouting pipe is exposed, grouting is performed through that grouting pipe to fill the goaf, repeating this process until the entire working face replenishment operation is completed. This invention utilizes the working face layout method used in high-intensity mining in western mining areas for replenishing goaf during mining, avoiding mining-replenishment interference and increasing the amount of gangue discharged through grouting.

Description

Technical Field

[0001] This invention belongs to the field of underground coal gangue emission reduction, specifically a method for underground coal gangue emission reduction by replenishing the goaf during mining. Background Technology

[0002] While coal mining yields resources, it also produces coal gangue, leading to environmental problems such as land occupation and pollution. As my country's efforts in ecological civilization construction continue to strengthen, the ecological environmental protection of coal mining areas is becoming increasingly prominent. Western my country is a major coal-producing region, and high-intensity mining is a typical characteristic of coal mining production in this area. Due to the high mining intensity and high coal production, the amount of coal gangue discharged is also large, resulting in significant environmental problems, which has become a top priority for environmental protection in coal mining areas.

[0003] Existing technologies propose grinding coal gangue into powder and drilling grouting holes on the surface to the goaf, discharging the gangue into the goaf for gangue reduction. However, due to the terrain in western China, surface drilling is difficult or the drilling locations are unsatisfactory. Furthermore, coal seams in western mines are generally shallow, with high mining activity, small residual fracture spaces in the goaf, poor groutability, and limited gangue discharge capacity; while traditional underground backfilling mining technology cannot meet the production capacity required for high-intensity mining in the west. Therefore, it is necessary to explore a method that can process large quantities of coal gangue without changing the original coal mining process, reducing mining-backfilling interference. Summary of the Invention

[0004] To address the shortcomings of the existing technologies, this invention proposes a method for reducing coal gangue emissions underground by replenishing goaf areas during mining, comprising the following steps:

[0005] a. Excavate the return airway in the upper part of the working face, and excavate the transport level and auxiliary level in the lower part of the working face; leave a section coal pillar between the transport level and the auxiliary level and connect them through the section connecting roadway; and open a cut-through to connect the return airway and the transport level.

[0006] Preferably, the auxiliary roadway is used as the return airway for the next working face in the later stage.

[0007] b. In the advanced working face mining area, directional grouting boreholes are drilled from the auxiliary roadway into the roof above the working face along the dip direction. The horizontal section of the directional grouting borehole is located in the roof strata above the working face. A grouting pipe with an outer diameter matching the diameter of the bare borehole is placed in the directional grouting borehole.

[0008] Preferably, in step b, the inclined section of the directional grouting borehole is located above the coal pillar of the section and dips from the auxiliary roadway toward the transport roadway.

[0009] Preferably, in step b, the horizontal section of the directional grouting borehole is located at the interface between the direct top and the basic top, and the portion located at the basic top is greater than the portion located at the direct top.

[0010] Preferably, in step b, the directional grouting boreholes are distributed at intervals along the working face advancing direction, with the interval being the distance of one cycle of pressure, and the directional grouting boreholes are located in the middle of the strike of the periodically fractured rock block.

[0011] Preferably, in step b, the grouting pipe is a perforated pipe in the horizontal section.

[0012] Preferably, in step b, during production at this working face, a track is laid in the auxiliary roadway, and the grouting pump and drilling rig are respectively fixed on a base that can run on the track.

[0013] c. When mining the working face, when a grouting pipe is exposed, grouting is carried out through the grouting pipe to fill the goaf. This process is repeated until the mining and filling work of the entire working face is completed.

[0014] Preferably, in step c, when the rock block where a grouting pipe is located collapses into the goaf, the grouting work of that grouting pipe is stopped.

[0015] Preferably, in step c, the grouting material is a slurry made by grinding coal gangue into powder and mixing it with water; the gangue comes from the underground mining face and the tunneling face, and is ground into powder directly underground; the water comes from underground water inflow and underground production wastewater.

[0016] Preferably, in step c, a protective device is installed behind the hydraulic support.

[0017] Beneficial Effects: This invention, based on the working face layout method during high-intensity mining in western mining areas, implements simultaneous mining and grouting in the goaf. Directional grouting drilling and grouting filling are arranged within auxiliary roadways, with the directional grouting boreholes positioned along the dip to delay grouting from the working face, preventing interference between mining and grouting. The directional grouting filling boreholes are located at the interface between the immediate roof and the main roof, and in the middle of the strike of the periodically fractured rock block, ensuring a long grouting filling time and a wide grouting coverage area, thereby increasing the grouting volume. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the working face of the goaf-filling and refilling method for underground coal gangue emission reduction according to the present invention.

[0019] Figure 2 This is a cross-sectional view of the working face of the coal gangue underground emission reduction and goaf filling method of the present invention.

[0020] Figure 3 This is a dip profile of the working face (unmined section) of the coal gangue underground emission reduction method for goaf filling during mining, as described in this invention.

[0021] Figure 4 This is a trend profile of the working face (already mined section) for coal gangue underground emission reduction in the goaf of this invention;

[0022] In the diagram: 1. Working face; 2. Transport roadway; 3. Auxiliary roadway; 4. Return air roadway; 5. Goaf; 6. Coal mining machine; 7. Hydraulic support; 8. Section coal pillar; 9. Section connecting roadway; 10. Direct roof; 11. Basic roof; 12. Directional grouting borehole / grouting pipe. Detailed Implementation

[0023] The following is an illustration of the embodiments of the present invention. Figure 1-4 The technical solution of the present invention will be described in more detail below.

[0024] A method for reducing coal gangue emissions underground by replenishing goaf areas during mining, comprising the following steps:

[0025] a. Working face 1 is arranged according to the original high-intensity mining working face layout. A return airway 4 is excavated at the upper dip of working face 1, and a transport roadway 2 and an auxiliary roadway 3 are excavated at the lower dip of working face 1. A section coal pillar 8 is left between transport roadway 2 and auxiliary roadway 3, with a width of 15-25m. Simultaneously, a section connecting roadway 9 is excavated at 30-40m intervals along the strike to connect transport roadway 2 and auxiliary roadway 3. The lengths of return airway 4, transport roadway 2, and auxiliary roadway 3 are the same as the length of working face 1, generally over 4000m, with dimensions of approximately 6m wide × 4m high. Auxiliary roadway 3 will later be used as the return airway for the next working face. The section connecting roadway 9 also adopts a size of 6m wide × 4m high. At the same time, a cut-in roadway is excavated to connect transport roadway 2 and return airway 4, and coal mining equipment, mainly including a coal mining machine 6 and hydraulic supports 7, is arranged within the cut-in roadway. Figure 1 A schematic diagram of the working face after it has advanced a certain distance.

[0026] b. The original function of return airway 4 remains unchanged, mainly used for return air, waste rock removal, drainage and material transportation. Tracks are laid at the bottom of return airway 4 for mine cars to transport materials and remove waste rock. The original function of transport roadway 2 remains unchanged, mainly used for coal transportation. It is equipped with a belt conveyor and is connected to the scraper conveyor in the mining area through a transfer machine and a crusher. Auxiliary roadway 3 adds filling-related processes to the original functions of pedestrian and air intake.

[0027] In the original production process, the auxiliary roadway 3 was only laid with tracks when the next working face was being mined, that is, when it was used as the return air roadway of the next working face. In this invention, the tracks are laid when the working face is being produced, that is, when it is used as an auxiliary roadway. The grouting pump and drilling rig are fixed on the base that can run on the tracks, which facilitates the movement of the grouting pump and drilling rig, without adding extra tracks and reducing damage to the floor of the auxiliary roadway.

[0028] This invention selects both the directional grouting drilling site and the grouting filling site in the auxiliary roadway. This selection is based on the fact that the auxiliary roadway has fewer production processes and no other large equipment inside. In the auxiliary roadway, pedestrian traffic is relatively concentrated, mainly during shift changes. The air intake does not affect other production processes involving large equipment. In other words, this invention makes full use of the original working face design and does not change the original production processes, achieving non-interference between mining and filling.

[0029] Specifically, in the advanced working face mining area, directional grouting boreholes 12 are drilled along the dip from the auxiliary roadway 2 towards the interface between the immediate roof 10 and the main roof 11 above the working face. The first section of the directional grouting borehole 12, i.e., the inclined section, is located above the section coal pillar 8, inclined from the auxiliary roadway 3 towards the transport roadway 2. The second section of the directional grouting borehole, i.e., the horizontal section, is located at the interface between the immediate roof 10 and the main roof 11, with the portion located at the main roof being more than the portion located at the immediate roof. The length of the horizontal section of the directional grouting borehole 12 is consistent with the width of the working face, generally about 300m. The directional grouting... The diameter of the borehole is preferably 20-30cm; the directional grouting boreholes are distributed at intervals along the working face advance direction, with a spacing of one cycle of pressure, approximately 25-35m, and the directional grouting boreholes are located in the middle of the strike of the periodically fractured rock block to ensure sufficient grouting time for each directional grouting borehole and wide grouting coverage; a grouting pipe with an outer diameter matching the diameter of the bare borehole is placed in the directional grouting borehole 12. The grouting pipe has a certain degree of flexibility to ensure that it does not break at the transition between the inclined and horizontal sections of the directional grouting borehole, and the grouting pipe is a perforated pipe in the horizontal section.

[0030] c. When working face 1 is being mined, and a grouting pipe is exposed during the mining process, grouting is carried out through the grouting pipe to fill the goaf. When the rock block where the grouting pipe / directional grouting borehole is located collapses into the goaf, the grouting work of the grouting pipe / directional grouting borehole is stopped. This process is repeated until the entire working face is mined and the entire goaf of the working face is filled.

[0031] The grouting material is a slurry made by grinding coal gangue into powder and mixing it with water. This can produce a high-concentration slurry, reducing the amount of water seeping into the mining area. At the same time, a retaining device is installed behind the hydraulic support to separate the mining area from the fluids and gravel near the bottom plate behind the goaf. The gangue comes from the gangue generated in the underground mining and tunneling faces and is directly crushed and ground into powder underground. The water comes from underground water inflow and underground production wastewater.

[0032] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A method for reducing coal gangue emissions underground by replenishing goaf areas during mining, characterized in that, Includes the following steps: a. Excavate the return airway in the upper part of the working face, and excavate the transport roadway and auxiliary roadway in the lower part of the working face; leave a section coal pillar between the transport roadway and the auxiliary roadway and connect them through the section connecting roadway; connect the return airway and the transport roadway by cutting a hole; the auxiliary roadway will be used as the return airway for the next working face in the later stage; b. In the advanced working face mining area, directional grouting boreholes are drilled along the dip direction from the auxiliary roadway into the roof above the working face; the directional grouting boreholes are distributed at intervals along the working face advancement direction, with the interval being the distance of one cycle of pressure, and the directional grouting boreholes are located in the middle of the strike of the periodically fractured rock block; the inclined section of the directional grouting borehole is located above the section coal pillar, inclined from the auxiliary roadway towards the transport roadway, and the horizontal section of the directional grouting borehole is located at the interface between the immediate roof and the main roof, and the length of the horizontal section of the directional grouting borehole is consistent with the width of the working face; a grouting pipe with an outer diameter matching the diameter of the bare borehole is placed in the directional grouting borehole, and the grouting pipe is a perforated pipe in the horizontal section; During production at this working face, tracks are laid in the auxiliary roadway, and the grouting pump and drilling rig are fixed on bases that can run on the tracks. c. When mining the working face, when a grouting pipe is exposed, grouting is carried out through the grouting pipe to fill the goaf area. This process is repeated until the mining and filling work of the entire working face is completed. The grouting material is a slurry made by grinding coal gangue into powder and mixing it with water. The gangue comes from the underground mining working face and the tunneling working face and is ground into powder directly underground.

2. The method for replenishing goaf during mining as described in claim 1, characterized in that, In step b, the portion of the horizontal section of the directional grouting borehole located at the base is greater than the portion located at the direct top.

3. The method for replenishing goaf during mining as described in claim 1 or 2, characterized in that, In step c, when the rock block where a grouting pipe is located collapses into the goaf, the grouting work of that grouting pipe is stopped.

4. The method for replenishing goaf during mining as described in claim 1 or 2, characterized in that, In step c, the water comes from underground well water inflow and underground production wastewater.

5. The method for replenishing goaf during mining as described in claim 1 or 2, characterized in that, In step c, a protective device is installed behind the hydraulic support.

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