Mining-and-filling-while-mining-and-filling-while-mining goaf space column filling and water-preserved mining method

Abstract

The invention discloses a mining and filling-while-mining goaf space column filling and water-preserved mining method. The mining and filling-while-mining goaf space column filling and water-preserved mining method comprises the steps that firstly, a rapid filling device behind a fully mechanized mining frame is assembled behind a hydraulic support; filling slurry is injected into the rapid filling device behind the fully-mechanized mining frame, and a filling stud is formed after the filling slurry forms early strength; a new rapid filling device is assembled in a fully-mechanized mining hydraulic support filling working area, the rapid filling device behind the fully-mechanized mining hydraulic support is moved along with advancing of a working face, formed filling spacing columns are completely arranged in a goaf to support a top plate, and a goaf fissure zone behind the working face is prevented from developing to a water-resisting layer; and the steps are circulated to finally form the whole row of filling studs in the length direction of the working face. According to the method, the large goaf formed by continuous caving is divided into the small goaf which is small in caving range and does not affect a water-resisting layer, the post-erection filling operation procedure is simplified, and effective disposal of coal gangue and effective control over development of three zones of the goaf are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of green filling mining in coal mines, and specifically relates to a method for mining and filling as the mining progresses, and a method for filling and water-retaining the mining column between goafs behind a fully mechanized mining frame. Background Art

[0002] Coal mining has made great contributions to ensuring my country's energy security and promoting industrial economic development, but the ecological environment damage and resource waste caused by coal mining also restrict the sustainable development of coal-producing areas. First, coal gangue accounts for 10% to 20% of coal mine production. Since 2011, the annual increase in gangue emissions has been 650 million to 700 million tons, and the cumulative stockpile has exceeded 8 billion tons, causing serious ground pollution and land occupation; second, coal mines use the caving method to deal with empty areas, causing damage to the structure of the groundwater system, lowering or even disappearing the water level of the aquifer, expanding the scope of surface subsidence, and destroying the surface morphology and the safety of buildings and structures; third, my country's coal resources under buildings, railways and water bodies and corner coal resources are huge, affecting the continued production of coal mines.

[0003] Gangue cementing and filling mining has significant advantages in coal-based solid waste disposal and utilization, surface subsidence control and environmental protection, and has become the main method of green mining in coal mines. However, in large-scale production mines, gangue cementing and filling faces problems such as complex filling material preparation process, poor slurry transportation stability, insufficient gangue for large-scale filling, high filling cost, and difficulty in achieving mining and filling balance.

[0004] The cemented filling mining of the goaf area behind the fully-mechanized working face is a large-scale filling coal mining method. It is necessary to set up the template before filling the goaf. The next step of coal cutting and frame moving can only be carried out after the filling body hardens to meet the strength requirements. It is difficult to achieve balanced operation between coal mining and filling, which limits the production capacity of the working face. The large-scale filling operation in the goaf area is large, and it is necessary to build a large-scale filling station for large-scale slurry making and pipeline transportation. The coal mine's own coal gangue aggregate volume is insufficient, and the working stability of the filling system is difficult to guarantee. Therefore, there is a need for a mining method for filling and water conservation between goaf intervals behind a fully-mechanized mining frame that has strong stability, high subsidence treatment efficiency, and can quickly construct inter-pillars for the filling body of the interval goaf area. Summary of the invention

[0005] The purpose of the present invention is to provide a method for filling and water-preserving goaf interval columns behind a comprehensive mining frame, which has strong stability, high subsidence treatment efficiency, and can quickly construct interval goaf filling body columns and fill as the goaf is filled. The method changes the idea of ​​goaf filling, and changes the continuous filling of large-area goafs to rapid filling of goaf interval columns behind the frame. The large goafs formed by continuous roof caving are separated into small goafs with a small caving range and no impact on the waterproof layer. At the same time, the filling operation volume is greatly reduced, and there is no need to add drainage pipelines. The post-frame filling operation procedure is simplified, and coal mining and filling are carried out in parallel, thereby realizing effective disposal of coal gangue and effective control of the development of the three zones in the goaf.

[0006] To achieve the above object, the present invention adopts the following technical solution: The method for filling and water-retaining mining of the goaf column behind the fully mechanized mining frame with mining and filling at the same time comprises the following steps: (1) Assemble the quick filling device behind the fully mechanized mining frame behind the hydraulic support; (2) Injecting filling slurry into the rapid filling device behind the fully mechanized mining frame, and forming a filling column after the filling slurry forms early strength; (3) Assemble the new fully mechanized mining frame and quickly fill the device, and move it with the advancement of the working face. The moving distance is such that the fracture zone in the goaf cannot develop into the impermeable layer. The formed filling column is completely placed in the goaf to support the roof, preventing the fracture zone in the goaf behind the working face from developing into the impermeable layer. (4) Injecting filling slurry into the new rapid filling device in step (3), and repeating steps (2) to (3), and finally forming a whole row of filling columns along the length direction of the working surface.

[0007] The quick filling device behind the fully mechanized mining frame comprises a filling workbench, a three-way grouting pipe and a filling mold. The filling workbench is arranged at the lower part of the rear side of the fully mechanized mining hydraulic support, the filling mold is arranged at the rear side of the filling workbench, the rear end of the three-way grouting pipe is connected to the inside of the filling mold, and a filling hydraulic baffle is arranged at the upper part of the rear side of the fully mechanized mining hydraulic support; The filling mold includes a mold top plate, a mold front side plate, a mold rear side plate, a mold left baffle plate and a mold right baffle plate. A plurality of mold cross braces arranged parallel to each other are arranged between the mold front side plate and the mold rear side plate. The bottoms of the mold front side plate and the mold rear side plate are placed on the coal seam bottom plate, and exhaust holes are opened on the mold top plate.

[0008] The front end of the mold cross brace is connected to the mold front side plate, and the rear end of the mold cross brace is connected to the mold rear side plate. Expansion bolt structures are arranged between the front end of the mold cross brace and the mold front side plate and between the mold cross brace and the mold rear side plate.

[0009] The front side plate of the mold and the rear side plate of the mold have the same structure, both including an upper side plate, a middle side plate, and a lower side plate. The top end of the upper side plate is connected to the front end of the mold top cover, the bottom end of the upper side plate and the bottom end of the middle side plate are both provided with connecting protrusions, the top end of the middle side plate and the top end of the lower side plate are both provided with connecting grooves corresponding to the connecting protrusions, and locking buckles are provided between the connection between the upper side plate and the middle side plate and the connection between the middle side plate and the lower side plate.

[0010] A front connecting plate assembly and a rear connecting plate assembly are arranged between the left baffle plate of the mold and the right baffle plate of the mold. The front connecting plate assembly and the rear connecting plate assembly have the same structure and both include a left connecting plate, a middle connecting plate and a right connecting plate. Trapezoidal grooves are arranged at the left ends of the left connecting plate, the middle connecting plate and the right connecting plate, and trapezoidal protrusions corresponding to the trapezoidal grooves are arranged at the right ends of the left baffle plate of the mold. A trapezoidal protrusion is arranged at the right end of the left baffle plate of the mold, and a trapezoidal groove is arranged at the left end of the right baffle plate of the mold.

[0011] The specific process of step (1) is as follows: ①Install the filling workbench on the rear side of the hydraulic support; ② The filling mold is assembled close to the filling workbench so that the filling workbench provides horizontal support for the filling mold; ③Install a three-way grouting pipe on the upper side plate of the filling mold; ④Install the filling hydraulic baffle on the upper rear side of the hydraulic support.

[0012] The specific operation process of step (2) is as follows: inject early strength filling slurry into the mold through the three-way grouting pipe, and drive anchor rods on the coal seam floor to fix it before grouting. The top of the anchor rod is connected to the mold cross support of the lowest layer of the mold, and the lower end of the anchor rod is fastened in the coal seam floor to prevent the filling mold from floating up during the grouting process.

[0013] The specific process of step ② is as follows: a. Assemble the front side plate and the rear side plate of the mold, install the upper side plate, the middle side plate and the lower side plate together through the connecting protrusions and the connecting grooves, and lock them with locking buckles at the connection; b. Install the mold top cover between the top of the mold front side plate and the mold rear side plate, and install several mold cross braces in parallel up and down between the mold front side plate and the mold rear side plate through the expansion bolt structure; c. Assemble the front connecting plate assembly and the rear connecting plate assembly of the mold, and assemble the left connecting plate, the middle connecting plate and the right connecting plate together through the trapezoidal grooves and the trapezoidal protrusions; d. Install the left baffle of the mold on the left end of the front connecting plate assembly and the rear connecting plate assembly, and install the right baffle of the mold on the right end of the front connecting plate assembly and the rear connecting plate assembly.

[0014] The length of each section of the filling mold is equal to the total width of a moving frame, and the width of each section of the filling mold is equal to the coal mining step distance.

[0015] The filling mold is made of lightweight and high-strength plastic material.

[0016] The present invention performs filling mold assembly, grouting and coal mining in parallel behind the comprehensive mining working face frame. The filling mold is quickly assembled in sections using mortise and tenon joints and a nested structure, and an accelerator is added to form the early strength of the filling body. The filling column is composed of a filling body formed by the filling mold and hardened filling slurry, and there is no need to dismantle the mold. The filling operation is flexible and safe, the labor intensity is low, it is convenient for intelligent control, and it is easy to achieve mining and filling balance.

[0017] The backfilling of the present invention is to inject the filling material slurry into the rectangular parallelepiped mold in sections to form filling columns, whose width is the coal mining step distance, and the total filling amount is greatly reduced, which can fully utilize the coal mine gangue and avoid the problem of insufficient filling aggregate.

[0018] Under the supporting effect of the filling pillars on the coal seam roof, the present invention changes the continuous collapse of the goaf under the traditional coal mining method into intermittent collapse, forming intermittent goaf areas isolated by filling pillars, significantly reducing the scope of the goaf, effectively controlling the expansion range of the caving area and the fissure area, preventing the development of induced fissures in the lower part of the impermeable layer, blocking the water conduction channel, protecting the aquifer, and inhibiting surface subsidence.

[0019] To sum up, the present invention is simple and convenient to operate, can be used for mining overburden coal seams and corner coal, and is conducive to promoting pillar-free mining, promoting the full development and utilization of coal resources, and realizing safe, efficient, green and sustainable mining of coal mines. It effectively solves the technical problems of low mining efficiency in existing methods due to insufficient volume of coal gangue aggregates in coal mines themselves and difficulty in ensuring the working stability of the filling system. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of the rapid filling device behind the fully mechanized mining frame of the present invention.

[0021] Figure 2 It is a structural schematic diagram of the filling mold of the present invention.

[0022] Figure 3 yes Figure 2 Enlarged view of part B in the middle.

[0023] Figure 4 yes Figure 2 Enlarged view of part C in the middle.

[0024] Figure 5 It is a left schematic view of the filling mold of the present invention.

[0025] Figure 6 yes Figure 2 Section view of the AA plane.

[0026] Figure 7 yes Figure 6 Enlarged view of part A in the middle.

[0027] Figure 8It is a schematic structural diagram of water-preserving mining in goaf areas with filling pillars according to the present invention. DETAILED DESCRIPTION

[0028] The embodiments of the present invention are further described below with reference to the accompanying drawings.

[0029] like Figure 1-8 As shown, the method of filling and water-retaining mining between goaf columns behind the fully mechanized mining frame with mining and filling at the same time is used for coal mining enterprises that perform filling mining or water-retaining mining, and is particularly suitable for mines that use the long-arm mining method or the inclined long-arm mining method working face 24 to advance and recover thick and medium-thick coal seams. It includes the following steps: (1) Assemble the quick filling device behind the fully mechanized mining frame behind the hydraulic support 1; (2) injecting the filling slurry 7 into the rapid filling device behind the fully mechanized mining frame, and forming the filling column 27 after the filling slurry 7 forms early strength; (3) After the filling slurry 7 hardens, a new fully mechanized mining frame is assembled with a quick filling device. As the working face 24 moves forward, the moving distance prevents the fracture zone of the goaf 26 from developing into the waterproof layer 20. The formed filling pillars 27 are completely placed in the goaf 26 to support the roof, preventing the fracture zone of the goaf 26 behind the working face 24 from developing into the waterproof layer 20. (4) Injecting the filling slurry 7 into the new rapid filling device in step (3), and circulate step (2) and step (3), so that a whole row of filling pillars 27 along the length direction of the working face 24 is finally formed in this cycle. The above steps are cyclically performed, and the filling pillars 27 change the continuous collapse of the roof under the traditional coal mining method into intermittent collapse, and isolate the continuous goaf 26 into intermittent goaf 26, effectively controlling the expansion range of the caving zone and the fracture zone, avoiding the generation of fractures in the impermeable layer 20, protecting the aquifer 19, preventing surface subsidence, and effectively treating the coal gangue to avoid the accumulation of gangue on the ground and causing environmental pollution in the mining area.

[0030] The rapid filling device behind the comprehensive mining frame includes a filling workbench 2, a three-way grouting pipe 3 and a filling mold 9. The filling workbench 2 is arranged at the lower rear part of the comprehensive mining hydraulic support 1, and the filling mold 9 is arranged at the rear side of the filling workbench 2. The rear end of the three-way grouting pipe 3 is connected to the inside of the filling mold 9, and a filling hydraulic baffle 5 is arranged on the upper rear side of the comprehensive mining hydraulic support 1; the grouting pipe suspended in the filling working space behind the comprehensive mining working face 24 hydraulic support 1 is a three-way grouting pipe 3, and the spacing of the filling branch pipes can be set according to the length of the filling mold 9. A PLC controller and a corresponding liquid level sensor can also be set to automatically control the filling pipe valve by sensing the liquid level position of the filling slurry 7 in the filling mold 9 that is about to be filled.

[0031] The filling mold 9 includes a mold top plate, a mold front side plate 10, a mold rear side plate 13, a mold left baffle 16 and a mold right baffle 18. A plurality of mold cross braces 6 arranged in parallel up and down are arranged between the mold front side plate 10 and the mold rear side plate 13. The bottoms of the mold front side plate 10 and the mold rear side plate 13 are placed on the coal seam bottom plate 14. An exhaust hole 4 is opened on the mold top plate. During the grouting process, the gas in the filling mold 9 is discharged from the exhaust hole 4 to ensure the uniform distribution of the filling slurry 7. The filling mold 9 is assembled in sections starting from the opening of the cutting eye, and is assembled close to the filling workbench 2 under the protection of the filling hydraulic baffle 5. The length of one section of the mold is the total width of a moving frame, and the mold width is equal to a coal mining step. After the assembly is completed, it moves forward with the advancement of the working face 24 under the protection of the filling hydraulic baffle 5. The moving distance prevents the fracture zone above the caving zone from developing to the waterproof layer 20 (the filling mold 9 moves with the hydraulic support 1 to an integer multiple of the coal mining cutting depth, and this size controls the roof fracture zone to not develop to the waterproof layer 20). Early-strength filling slurry 7 is injected into the mold through the three-way grouting pipe 3, and the filling body and the mold together form a filling column 27. The filling column 27 isolates the goaf 26 in sections, controls the roof caving range and the crack expansion depth, and protects the waterproof layer 20 and the aquifer 19. After the filling body forms early strength, the hydraulic support 1 is moved to a depth, and a new comprehensive mining frame rear rapid filling device is quickly assembled between the filling workbench 2 and the previous filling column 27 under the protection of the filling hydraulic baffle 5. After the assembly is completed, it moves forward with the working face 24 to move a small goaf 26 span, and then injects the early strength filling slurry 7 to form the second filling column 27. The front end of the mold cross brace 6 is connected to the mold front side plate 10, and the rear end of the mold cross brace 6 is connected to the mold rear side plate 13. An expansion bolt structure 11 is provided between the front end of the mold cross brace 6 and the mold front side plate 10 and between the mold cross brace 6 and the mold rear side plate 13. The expansion bolt structure 11 is mortised to improve the stability of the filling mold 9 and prevent the side plate from being excessively deformed under the horizontal stress of the gangue and the hydrostatic pressure of the slurry. Filling pillars 27 are used to fill the goaf 26, and the continuous collapse of the roof is changed into interval collapse, which effectively controls the scope of the caving zone and the fracture zone, protects the aquifer 19 and the surface, and effectively treats the coal gangue, realizes parallel mining and filling operations, and improves the efficiency of green mining.

[0032] The front side plate 10 of the mold and the rear side plate 13 of the mold have the same structure, both including an upper side plate, a middle side plate, and a lower side plate. The top end of the upper side plate is connected to the front end of the mold top cover 15, and the bottom end of the upper side plate and the bottom end of the middle side plate are both provided with connecting protrusions 29, and the top end of the middle side plate and the top end of the lower side plate are both provided with connecting grooves 30 corresponding to the connecting protrusions 29, and locking buckles 12 are provided between the connection between the upper side plate and the middle side plate and the connection between the middle side plate and the lower side plate.

[0033] A front connecting plate assembly and a rear connecting plate assembly are arranged between the left baffle plate 16 and the right baffle plate 18 of the mold. The front connecting plate assembly and the rear connecting plate assembly have the same structure, and both include a left connecting plate, a middle connecting plate and a right connecting plate. The left ends of the left connecting plate, the middle connecting plate and the right connecting plate are provided with a trapezoidal groove 32, and the right ends of the left connecting plate, the middle connecting plate and the right connecting plate are provided with a trapezoidal protrusion 31 corresponding to the trapezoidal groove 32. The right end of the left baffle plate 16 of the mold is provided with a trapezoidal protrusion 31, and the left end of the right baffle plate 18 of the mold is provided with a trapezoidal groove 32. The filling mold 9 can withstand the hydrostatic pressure of the filling slurry 7 in all directions through the embedded connection between the connecting groove 30 and the connecting protrusion 29 and the embedded connection between the trapezoidal groove 32 and the trapezoidal protrusion 31; after the filling mold 9 is assembled, it is linked with the filling workbench 2 behind the frame to prevent the falling gangue from pouring into the filling operation area 25. The assembly of the filling mold 9, the filling grouting and the coal cutting by the coal mining machine are carried out simultaneously. After the grouting in the filling mold 9 is completed and the filling body forms early strength, the hydraulic support 1 is moved one step, and the formed filling column 27 is still under the protection of the filling hydraulic baffle 5; a new filling mold 9 is assembled between the filling workbench 2 and the filling column 27, and the goaf 26 spacing distance allowed is moved as the working face 24 advances. After grouting, a new filling body column is constructed. After the interaction between the column and the roof, the column and the previous filling body column change the stress distribution of the roof together, isolate a number of discontinuous small goaf 26, and limit the formation of a water-conducting channel of the waterproof layer 20 on the upper part of the goaf 26.

[0034] The specific process of step (1) is as follows: ① Install the filling workbench 2 on the rear side of the hydraulic support 1; ② The filling mold 9 is assembled close to the filling workbench 2, so that the filling workbench 2 provides horizontal support for the filling mold 9; ③ Install the three-way grouting pipe 3 on the upper side plate of the filling mold 9; ④ Install the filling hydraulic baffle 5 on the upper rear side of the hydraulic support 1.

[0035] The specific operation process of step (2) is as follows: inject early strength filling slurry 7 into the mold through the three-way grouting pipe 3, and before grouting, drive anchor rods 8 on the coal seam bottom plate 14 for fixing. The top end of the anchor rod 8 is connected to the mold cross brace 6 at the bottom layer of the mold, and the lower end of the anchor rod 8 is fastened in the coal seam bottom plate 14 to prevent the filling mold 9 from floating up during the grouting process.

[0036] The specific process of step ② is as follows: a. Assemble the front side plate 10 and the rear side plate 13 of the mold, install the upper side plate, the middle side plate and the lower side plate together through the connecting protrusion 29 and the connecting groove 30, and lock them at the connection using the locking buckle 12; b. Install the mold top cover 15 between the top of the mold front side plate 10 and the mold rear side plate 13, and install a plurality of mold cross braces 6 in parallel up and down between the mold front side plate 10 and the mold rear side plate 13 through the expansion bolt structure 11; c. Assemble the front connecting plate assembly and the rear connecting plate assembly of the mold, and assemble the left connecting plate, the middle connecting plate and the right connecting plate together through the trapezoidal groove 32 and the trapezoidal protrusion 31; d. Install the left baffle plate 16 of the mold on the left end of the front connecting plate assembly and the rear connecting plate assembly, and install the right baffle plate 18 of the mold on the right end of the front connecting plate assembly and the rear connecting plate assembly. In addition, the assembly and grouting of the filling mold 9 are carried out in parallel with the coal mining of the working face 24. The filling slurry 7 used is added with an early strength agent, which must be able to form early strength within 12 hours. Accelerators are added during grouting. The early hardening of the filling body should be completed at the end of the inspection shift, which will not affect the advancement and shifting of the working face 24, and ensure the safety of the assembly of the new mold after the shifting. The shifting of the frame in groups can also be carried out alternately, so that the hardening of the filling body, the assembly of the new mold, and the shifting of the frame can be carried out alternately.

[0037] The length of each section of the filling mold 9 is equal to the total width of one shifting frame, and the width of each section of the filling mold 9 is equal to one coal mining step.

[0038] The filling mold 9 is made of a lightweight and high-strength plastic material and can be integrally cast and formed at a low cost. The filling mold 9 is transported to the working surface 24 and quickly assembled under the protection of the filling hydraulic baffle 5. The labor intensity is low and robots can also be used to assist the operation to improve efficiency and reduce labor.

[0039] In addition, in order to improve the treatment efficiency of goaf 26 subsidence, some coal mines adopt the methods of separation grouting and high-position drilling grouting, adjacent grouting and low-position grouting in goaf 26. Separation grouting requires the geological conditions of separation of the key rock layer 23, the key layer is thick and there is a deformable rock layer 23 below it; the grouting in the goaf 26 is prone to slurry leakage, polluting the working face 24 and the mining tunnel, the plugging workload is large, the high-position drilling cost is high, the drilling accuracy is difficult to control when the mining depth is large, and the difficulty of drilling in the fracture zone is large; the adjacent grouting and low-position grouting underground filling and drainage pipeline layout are complicated, and the manual work volume is large. The present invention carries out the assembly of the filling mould 9, grouting and coal mining in parallel behind the comprehensive mining working face 24. The filling mould 9 is quickly assembled in sections by mortise and tenon joints and nested structures, and a quick-setting agent is added to form the early strength of the filling body. The filling column 27 is composed of a filling body formed by the filling mould 9 and the hardened filling slurry 7, and there is no need to dismantle the mould. The filling operation is flexible and safe, the labor intensity is low, it is convenient for intelligent control, and it is easy to achieve mining and filling balance.

[0040] The backfilling of the present invention is to inject the filling material slurry 7 into the rectangular parallelepiped mold in sections to form filling columns 27, whose width is the coal mining step distance, and the total filling amount is greatly reduced, which can fully utilize the coal mine gangue and avoid the problem of insufficient filling aggregate.

[0041] Under the supporting effect of the filling pillars 27 on the coal seam roof 21, the present invention changes the continuous collapse of the goaf 26 under the traditional coal mining method into intermittent collapse, forming intermittent goaf 26 isolated by the filling pillars 27, significantly reducing the range of the goaf 26, effectively controlling the expansion range of the caving area and the fissure area, preventing the development of induced fissures in the lower part of the impermeable layer 20, blocking the water conduction channel, protecting the aquifer 19, and inhibiting surface subsidence.

[0042] In summary, the present invention is simple and convenient to operate, can be used for mining overburden coal seams 22 and corner coal, and is conducive to promoting pillar-free mining, promoting the full development and utilization of coal resources, and realizing safe, efficient, green and sustainable mining of coal mines. It effectively solves the technical problems of low mining efficiency caused by the existing methods due to insufficient volume of coal gangue aggregates in the coal mine itself and difficulty in ensuring the working stability of the filling system.

[0043] The above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention is described in detail with reference to the above embodiments, those skilled in the art should understand that the present invention can still be modified or replaced by equivalents. Any modification or partial replacement that does not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A method for filling and water-retaining mining with columns in the goaf behind a fully mechanized mining frame with mining and filling as the goaf progresses, characterized in that: The steps include: (1) Assemble the quick filling device behind the fully mechanized mining frame behind the hydraulic support; (2) Injecting filling slurry into the rapid filling device behind the fully mechanized mining frame, and forming a filling column after the filling slurry forms early strength; (3) Assemble the new fully mechanized mining frame and quickly fill the device, and move it with the advancement of the working face. The moving distance is such that the fracture zone in the goaf cannot develop into the impermeable layer. The formed filling column is completely placed in the goaf to support the roof, preventing the fracture zone in the goaf behind the working face from developing into the impermeable layer. (4) Injecting filling slurry into the new rapid filling device in step (3), and repeating steps (2) to (3), and finally forming a whole row of filling columns along the length direction of the working surface.

2. The method for filling and water-retaining mining with columns behind the goaf of a fully mechanized mining frame according to claim 1 is characterized in that: The quick filling device behind the fully mechanized mining frame comprises a filling workbench, a three-way grouting pipe and a filling mold. The filling workbench is arranged at the lower part of the rear side of the fully mechanized mining hydraulic support, the filling mold is arranged at the rear side of the filling workbench, the rear end of the three-way grouting pipe is connected to the inside of the filling mold, and a filling hydraulic baffle is arranged at the upper part of the rear side of the fully mechanized mining hydraulic support; The filling mold includes a mold top plate, a mold front side plate, a mold rear side plate, a mold left baffle plate and a mold right baffle plate. A plurality of mold cross braces arranged parallel to each other are arranged between the mold front side plate and the mold rear side plate. The bottoms of the mold front side plate and the mold rear side plate are placed on the coal seam bottom plate, and exhaust holes are opened on the mold top plate.

3. The method for filling and water-retaining mining with columns in the goaf behind the fully mechanized mining frame according to claim 2 is characterized in that: The front end of the mold cross brace is connected to the mold front side plate, and the rear end of the mold cross brace is connected to the mold rear side plate. Expansion bolt structures are arranged between the front end of the mold cross brace and the mold front side plate and between the mold cross brace and the mold rear side plate.

4. The method for filling and water-retaining mining with columns in the goaf behind a fully mechanized mining frame according to claim 3 is characterized in that: The front side plate of the mold and the rear side plate of the mold have the same structure, both including an upper side plate, a middle side plate, and a lower side plate. The top end of the upper side plate is connected to the front end of the mold top cover, the bottom end of the upper side plate and the bottom end of the middle side plate are both provided with connecting protrusions, the top end of the middle side plate and the top end of the lower side plate are both provided with connecting grooves corresponding to the connecting protrusions, and locking buckles are provided between the connection between the upper side plate and the middle side plate and the connection between the middle side plate and the lower side plate.

5. The method for filling and water-retaining mining with columns behind the goaf of a fully mechanized mining frame according to claim 4, characterized in that: A front connecting plate assembly and a rear connecting plate assembly are arranged between the left baffle plate of the mold and the right baffle plate of the mold. The front connecting plate assembly and the rear connecting plate assembly have the same structure and both include a left connecting plate, a middle connecting plate and a right connecting plate. Trapezoidal grooves are arranged at the left ends of the left connecting plate, the middle connecting plate and the right connecting plate, and trapezoidal protrusions corresponding to the trapezoidal grooves are arranged at the right ends of the left baffle plate of the mold. A trapezoidal protrusion is arranged at the right end of the left baffle plate of the mold, and a trapezoidal groove is arranged at the left end of the right baffle plate of the mold.

6. The method for filling and water-retaining mining with columns behind the goaf of a fully mechanized mining frame according to claim 5 is characterized in that: The specific process of step (1) is as follows: ①Install the filling workbench on the rear side of the hydraulic support; ② The filling mold is assembled close to the filling workbench so that the filling workbench provides horizontal support for the filling mold; ③Install a three-way grouting pipe on the upper side plate of the filling mold; ④Install the filling hydraulic baffle on the upper rear side of the hydraulic support.

7. The method for filling and water-retaining mining with columns in the goaf behind a fully mechanized mining frame according to claim 5 is characterized in that: The specific operation process of step (2) is as follows: inject early strength filling slurry into the mold through the three-way grouting pipe, and drive anchor rods on the coal seam floor to fix it before grouting. The top of the anchor rod is connected to the mold cross support of the lowest layer of the mold, and the lower end of the anchor rod is fastened in the coal seam floor to prevent the filling mold from floating up during the grouting process.

8. The method for mining and filling as the mining progresses and retaining water behind the goaf of a fully mechanized mining frame according to claim 6 is characterized in that: The specific process of step ② is as follows: a. Assemble the front side plate and the rear side plate of the mold, install the upper side plate, the middle side plate and the lower side plate together through the connecting protrusions and the connecting grooves, and lock them with locking buckles at the connection; b. Install the mold top cover between the top of the mold front side plate and the mold rear side plate, and install several mold cross braces in parallel up and down between the mold front side plate and the mold rear side plate through the expansion bolt structure; c. Assemble the front connecting plate assembly and the rear connecting plate assembly of the mold, and assemble the left connecting plate, the middle connecting plate and the right connecting plate together through the trapezoidal grooves and the trapezoidal protrusions; d. Install the left baffle of the mold on the left end of the front connecting plate assembly and the rear connecting plate assembly, and install the right baffle of the mold on the right end of the front connecting plate assembly and the rear connecting plate assembly.

9. The method for mining and filling as the mining progresses behind the fully mechanized mining frame and retaining water is characterized by: The length of each section of the filling mold is equal to the total width of a moving frame, and the width of each section of the filling mold is equal to the coal mining step distance.

10. The method for mining and filling as the mining progresses behind the fully mechanized mining frame and for water conservation is characterized in that: The filling mold is made of lightweight and high-strength plastic material.

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