Method and system for treating gangue through paste-slurry combined filling under cutting-off type roof condition

Abstract

The invention discloses a method for treating gangue through paste-slurry combined filling under the condition of a cut-off type roof, which specifically comprises the following steps: obtaining the yield and particle size distribution of mine gangue according to a product balance table for guiding a paste filling system, an underground coal gangue separation system and a slurry filling system; filling spacing is dynamically adjusted according to the lithology of the roof, the filling spacing is determined by controlling the number of intervals of the supports, it is guaranteed that a paste roof-contacted supporting roof rock stratum collapses, and a stable slurry filling space is constructed; gangue in a ground gangue bin enters a slurry filling system and automatically flows to a slurry pump to be pumped to the position above a working face along a filling pipeline, vertical drilling is constructed in an underground goaf to the position above a slurry filling space, and the filling pipeline is arranged to complete filling; the large-scale disposal of all gangues above and below the mine is completed according to continuous and sequential circulation of mine excavation. By means of paste-slurry filling combined operation, all underground filling treatment of underground gangue solid waste of the million-ton level is achieved, support to a top plate is reinforced through paste-slurry combination, and mine pressure is effectively weakened.

Description

Technical Field

[0001] This invention belongs to the field of coal mine backfilling technology, specifically relating to a method for treating gangue using a paste-slurry combined backfilling under sheared roof conditions, and also relating to a system for treating gangue using a paste-slurry combined backfilling under sheared roof conditions. Background Technology

[0002] The Shaanbei mining area is a coal production base with an annual output of hundreds of millions of tons, and it is also a production mining area mainly characterized by shallow coal seams. Due to the high mining intensity, simple overlying rock structure, and significant impact of surface load transmission, shallow coal seam mining often exhibits strong mine pressure manifestations. Because the roof has a stepped rock beam structure, it is prone to step subsidence or shearing collapse.

[0003] Against this backdrop, coal mining faces three main challenges: First, high-intensity mining generates millions of tons of coal gangue, but the capacity of gangue resource utilization technologies is limited, meaning that not all gangue can be disposed of and it must be stockpiled or temporarily stored. Second, large-scale gangue transport to surface coal washing plants using the mine transportation system results in significant inefficient transportation, wasting mine capacity and increasing transportation costs. Third, roof collapses during mining leave no overburden separation zone, and underground goaf areas are largely compacted. Traditional overburden separation grouting technology and goaf slurry filling technology, which are mainly based on large-scale gangue disposal, are not applicable. Solid and paste filling technologies have limited capacity to dispose of gangue and cannot fill all of it. Summary of the Invention

[0004] The purpose of this invention is to provide a method for the combined backfilling and disposal of gangue under the condition of sheared roof, which uses a combination of paste and slurry backfilling to achieve the underground backfilling and disposal of all gangue solid waste of millions of tons in the mine.

[0005] The technical solution adopted in this invention is a method for treating gangue using a combined paste-grout backfill under sheared roof conditions, specifically implemented according to the following steps: Step 1: Obtain the mine gangue production and particle size distribution based on the coal preparation plant's product balance sheet. This information will guide the design capacity and equipment selection for the paste filling system, underground coal and gangue sorting system, and slurry filling system. Step 2: Dynamically adjust the filling spacing according to the lithology of the roof. The filling spacing is determined by controlling the number of support intervals to ensure that the grout supports the roof rock layer from collapsing and to construct a stable grout filling space. Simultaneously, the gangue from the surface gangue bin enters the grout filling system, is crushed, screened, and ball-milled into gangue powder, and is mixed with water to form grout. The grout is then mixed in a mixing tank and flows by gravity to the mud pump, which pumps it along the filling pipeline to the top of the working face. Vertical drilling is then carried out in the underground goaf area to the top of the grout filling space, and filling pipelines are laid to complete the filling. Step 3: Based on the mining sequence, complete the large-scale disposal of all gangue from the mine.

[0006] The invention is further characterized in that, In step 2, the formula for calculating the maximum number of stent intervals is as follows:

[0007] In the formula: L MAX The maximum number of infill support intervals is expressed in supports; h is the rock stratum thickness in meters; h1, h2…h n The thicknesses of the first, second, ..., nth rock layers are represented by: R, tensile strength of the rock layer (MPa), and elastic modulus of the rock layer (MPa). E1, E2, ..., E... n The elastic modulus of the first, second, ..., nth rock strata is represented by γ, which is the volumetric force of the rock strata, in units of MN / m. 3 ;γ1, γ2…γ n L represents the volumetric force of the first rock layer, the second rock layer, ..., the nth rock layer; C The center-to-center distance of the filling support is measured in meters (m).

[0008] Center distance L of filling support C Specifically, it can be any one of 1.5m, 1.75m, 2.05m, or 2.4m.

[0009] Number of stents being filled k The calculation formula is as follows:

[0010] In the formula: Q J The amount of gangue backfilled in the well is expressed in t / a; h c The filling height is in meters (m). n c represents the daily feed rate; c represents the cycle feed rate in meters; L Z The center-to-center distance of the filling stent is in meters; t is the normal circulation rate. This refers to the density of the paste, expressed in t / m³. 3 ; M 1 represents the mass concentration of gangue in the paste-like filling material; K This indicates the number of stents being filled. Q J The amount of gangue used for ground filling is expressed in tons per year (t / a). This refers to the density of the slurry, expressed in t / m³. 3 ; M 2 represents the mass concentration of gangue used as the slurry filling material; L represents the length of the working face.

[0011] The number of stents being inflated can be calculated using the above formula. K The value range is within the range where the spacing between the filling supports does not exceed L. MAXIn the case of roof lithology, if the saturated uniaxial compressive strength of the roof is >30 MPa, k takes a smaller value; if the saturated uniaxial compressive strength of the roof is <30 MPa, k takes a larger value.

[0012] The formula for calculating the fillable height is: h c =h1φ, where h1 is the coal seam thickness in meters; φ is the fill ratio.

[0013] The filling spacing of the paste is controlled by the paste filling branch pipe and the three-way valve. When the paste filling branch pipe and the three-way valve are opened, the filling paste is pumped to the flexible mold bag behind the paste filling support to support the collapse of the top rock layer and construct a stable slurry filling space.

[0014] The paste filling process is as follows: Raw coal from the coal face is transported to the upper opening of the bottom coal bunker via a coal conveyor belt. The undersize material from the roller screen enters the bottom coal bunker and is transported to the surface coal washing plant for washing along the existing mine transportation system. The washed coal gangue enters the surface gangue bunker for buffering. The oversize material from the roller screen enters the intelligent dry separation chamber. The clean coal separated by the intelligent dry separator is returned to the bottom coal bunker via a return coal conveyor belt. The separated gangue enters the underground gangue bunker for buffering. The gangue in the underground gangue bunker is then processed by a primary crusher and a secondary crusher. The material is crushed and screened by a grading screen. After passing the qualified particle size, it is stored in the finished product gangue silo. Cement and additives are transported to the cement silo and additive silo respectively. The material is fed onto the centralized feeding belt according to the proportion. The centralized feeding belt transports all the filling materials to the intermittent mixer, adds water and mixes. The paste is discharged into the filling plunger pump. The filling plunger pump pumps the paste into the flexible mold bag behind the paste filling support at the working face. The mass ratio of gangue, cement and water in the paste material is 0.64:0.16:0.2.

[0015] The slurry filling process is as follows: the gangue is crushed by a crusher, screened by a tension screen, and ball-milled by a ball mill to produce gangue powder of qualified particle size. Water is added to make slurry to form slurry filling liquid. The slurry filling liquid enters the mixing tank for mixing and flows by gravity to the mud pump, which pumps it to the top of the working face along the slurry filling pipeline. Based on the mine geological data, vertical holes are precisely drilled into the goaf area underground to the top of the slurry filling space, and filling pipelines are arranged to complete the filling.

[0016] The density of the grout used for filling is 1.2 t / m³. 3 ~1.5t / m 3 .

[0017] The beneficial effects of this invention are: 1. The system of the present invention utilizes a combined paste-slurry filling operation to achieve underground filling and disposal of all million-ton-level gangue solid waste in mines, reducing ineffective gangue transportation and eliminating the environmental impact and safety hazards caused by gangue surface accumulation to water bodies, soil, and atmosphere.

[0018] 2. Since the working face roof collapses in a shearing or step-down manner, it is characterized by suddenness, penetration and strong destructive force. This invention uses paste filling to control the movement of overburden, timely control the collapse of the roof, and paste filling to dispose of solid waste, further strengthening the support of the roof, effectively reducing mine pressure, and solving problems such as sand and water collapse at the working face and the appearance of step-shaped cracks or sinkholes on the surface. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the arrangement of the paste filling system in the paste-slurry combined backfilling system for treating gangue under the condition of sheared roof of the present invention. Figure 2 This is a cross-sectional view of the layout of the underground coal and gangue sorting system in the slurry-grout combined backfilling system for gangue disposal under the sheared roof condition of the present invention. Figure 3 This is a schematic diagram of the layout of the paste-filled roadway in the paste-slurry combined backfilling system for treating gangue under the condition of sheared roof according to the present invention. Figure 4 This is a schematic diagram of the slurry filling system layout in the slurry-grout combined backfilling system for treating gangue under the condition of sheared roof of the present invention. Figure 5 This is a schematic diagram of ground grouting in the grout-slurry combined backfilling system for treating gangue under the sheared roof conditions of the present invention.

[0020] In the diagram, 1. Auxiliary transport roadway, 2. Main paste filling pipe, 3. Branch paste filling pipe, 4. Three-way valve, 5. Flexible mold bag, 6. Paste filling support, 7. Glue transport roadway, 8. Coal conveyor belt, 9. Coal mining machine, 10. Scraper conveyor, 11. Bottom coal bunker, 12. Roller screen, 13. Coal feeding belt, 14. Distributor, 15. Intelligent dry separator, 16. Intelligent dry separator control system, 17. Branch chute, 18. Return coal belt, 19. Underground gangue bunker, 20. Intelligent dry separator chamber, 21. Primary crusher, 22. Dust collector, 23. Coal feeding belt. 24. Iron separator; 25. Secondary crusher; 26. Grading screen; 27. Return waste conveyor belt; 28. Finished waste gangue bin; 29. ​​Cement bin; 30. Additive bin; 31. Weighing feeder; 32. Centralized feeding conveyor belt; 33. Intermittent mixer; 34. Filling plunger pump; 35. Emergency buffer pool; 36. Flushing pool; 37. Slurry filling pipeline; 38. Mud pump; 39. Mixing pool; 40. Ground waste gangue bin; 41. Slurry filling system; 42. Feeding conveyor belt; 43. Crusher; 44. Return waste conveyor belt; 45. Tension screen; 46. Ball mill. Detailed Implementation The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0021] Example 1 The present invention relates to a paste-slurry combined backfilling system for treating gangue under sheared roof conditions, such as... Figure 1 As shown, it includes a paste filling system, a slurry filling system 41, and an underground coal and gangue sorting system; the paste filling system is arranged in the underground coal mining face of the coal mine; The paste filling system includes a paste filling main pipe 2, a paste filling branch pipe 3, a three-way valve 4, a flexible mold bag 5, and a paste filling support 6; The main paste filling pipe 2 is connected to multiple paste filling branch pipes 3. The paste filling branch pipes 3 lead to each layer of paste filling space. A three-way valve 4 is provided at the connection between the main paste filling pipe 2 and the paste filling branch pipes 3. The paste filling support 6 is arranged in each layer of paste filling space. A flexible mold bag 5 is provided behind the paste filling support 6 for filling paste. The end of the paste filling branch pipe 3 is connected to the flexible mold bag 5. Coal mining machine 9 is the core equipment for raw coal mining, scraper conveyor 10 is the transfer and conveying equipment within the working face, and coal conveyor belt 8 is the cross-regional external transportation equipment. The paste filling main pipe 2 is arranged in the auxiliary transport roadway 1, and the coal conveyor belt 8 is arranged in the rubber transport roadway 7; the auxiliary transport roadway 1 and the rubber transport roadway 7 are parallel to the coal mining face and are located above and below the coal mining face respectively. The raw coal in the underground coal and gangue sorting system comes from the coal mining system of the coal mining face and the coal mining system of the tunneling face. It is mined by the coal mining machine 9 and transferred to the upper opening of the coal bunker 11 at the bottom of the shaft by the scraper conveyor 10. The scraper conveyor 10 is connected to the coal conveying belt 8. like Figure 2 As shown, the underground coal and gangue sorting system includes a bottom coal bunker 11, a roller screen 12 arranged at the top of the bottom coal bunker 11, and a coal conveyor belt 8 connected to the roller screen 12; an intelligent dry separation chamber 20 is set on one side of the bottom coal bunker 11, and a coal feeding belt 13, a material distributor 14, an intelligent dry separator 15, and an intelligent dry separation control system 16 are arranged inside the intelligent dry separation chamber 19. The coal conveyor belt 13 is arranged along the feeding direction of the intelligent dry separation chamber 19, with one end connected to the roller screen 12 and the other end extending to the receiving port of the distributor 14. The discharge port of the distributor 14 is connected to the feeding port of the intelligent dry separator 15. The intelligent dry separation control system 16 is used to control the movement of the intelligent dry separator 15, the coal conveyor belt 13, and the distributor 14. Below the intelligent dry separator 15 is a bifurcated chute 17, one end of which is connected to the coal return conveyor belt 18, and the other end is connected to the underground gangue bin 19; Figure 3As shown, the lower end of the underground gangue bin 19 is connected to the paste filling roadway 38. The paste filling roadway 38 is arranged in sequence with a primary crusher 21, a dust collector 22, an upper gangue conveyor belt 23, an iron remover 24, a secondary crusher 25, a grading screen 26, a return gangue conveyor belt 27, a finished gangue bin 28, a cement bin 29, an additive bin 30, a weighing feeder 31, a centralized feeding conveyor belt 32, an intermittent mixer 33, a filling plunger pump 34, an emergency buffer pool 35, and a flushing pool 36.

[0022] like Figure 3 As shown, the primary crusher 21 is fixed at the front end of the paste filling tunnel 38, and its feed inlet is connected to the bottom gangue bin 19. A dust collector 22 is installed above the discharge port of the primary crusher 21. The upper gangue conveyor belt 23 is arranged along the direction of the paste filling tunnel 38. The feed inlet of the upper gangue conveyor belt 23 is connected to the primary crusher 21, and the discharge port of the upper gangue conveyor belt 23 is connected to the feed end of the iron separator 24. The discharge end of the iron separator 24 is connected to the feed inlet of the secondary crusher 25, and the discharge port of the secondary crusher 25 is connected to the feed end of the grading screen 26. The grading screen 26 is fixed at an incline on the support, and the screened material is directly opposite the feed inlet of the finished gangue bin 28. The discharge port of the grading screen 26 is connected to the feed end of the return gangue conveyor belt 27. An inclined conveyor belt 27 is arranged in the paste filling tunnel 38, with one end lower than the discharge port of the grading screen 26 and the other end higher than the feed port of the secondary crusher 25. The paste filling tunnel 38 is also equipped with finished gangue bins 28, cement bins 29, and additive bins 30. Weighing feeders 31 are installed at the bottom of each of the finished gangue bins 28, cement bins 29, and additive bins 30. A centralized feeding belt 32 is laid at an incline behind the weighing feeder 31. The feed inlet of the intermittent mixer 33 is directly opposite the guide hopper of the centralized feeding belt 32. The bottom discharge port of the intermittent mixer 33 is connected to the filling plunger pump 34 through a pipeline. The paste filling pipeline is installed along the bottom of the paste filling roadway 38 and connects to the paste filling main pipe 2 in the auxiliary transport roadway 1. The emergency buffer pool 35 is located on one side of the intermittent mixer 33; the flushing pool 36 is located on one side of the filling plunger pump 34. like Figure 4As shown, a ground-level coal washing plant is surrounded by a ground-level gangue silo 40 and a slurry filling system 41. The slurry filling system 41 consists of a feeding belt 42, a crusher 43, a return belt 44, a tension screen 45, a ball mill 46, a mixing tank 39, a mud pump 38, and a slurry filling pipeline 37. The ground-level gangue silo 40 is connected to the feeding belt 42, which is connected to the crusher 43. The crusher 43 receives the discharge from the feeding belt 42. The feed end of the return belt 44 is connected to the tension screen 45, and the discharge port of the return belt 44 extends into the feed port of the crusher 43, realizing the recycling and crushing of materials until the screening and grading requirements are met. The qualified material passing through the tension screen 45 is fed into the inlet of the ball mill 46, and the outlet of the ball mill 46 is connected to the mixing tank 39; the bottom of the mixing tank 39 is connected to the mud pump 38, and the outlet of the mud pump 38 is connected to one end of the slurry filling pipe 37, such as... Figure 5 As shown, the other end of the slurry filling pipe 37 extends into the slurry filling space.

[0023] Example 2 The present invention provides a method for treating gangue using a combined paste-grout backfill under sheared roof conditions, which is implemented according to the following steps: Step 1: Based on the product balance sheet of the coal preparation plant, understand the mine gangue production and particle size distribution to accurately guide the design capacity and equipment selection of the paste filling system, underground coal gangue sorting system and slurry filling system. Step 2: Dynamically adjust the filling spacing according to the lithology of the roof. The filling spacing is determined by controlling the number of support intervals to ensure that the grout supports the roof strata from collapsing and to construct a stable grout filling space. Simultaneously, the gangue from the surface gangue bin 40 enters the grout filling system 41, is crushed, screened, and ball-milled into gangue powder of qualified particle size, and is mixed with water to make a grout of a specific concentration. It is then mixed in the mixing tank 39 and flows by gravity to the mud pump 38, which pumps it to the top of the working face along the filling pipeline. Based on the mine geological data, a vertical borehole is precisely drilled into the goaf underground to the top of the grout filling space, and the filling pipeline is arranged to complete the filling.

[0024] The formula for calculating the maximum number of stent intervals is as follows:

[0025] In the formula: L MAX The maximum number of infill support intervals is expressed in supports; h is the rock stratum thickness in meters; h1, h2…h n The thicknesses of the first, second, ..., nth rock layers are represented by: R, tensile strength of the rock layer (MPa), and elastic modulus of the rock layer (MPa). E1, E2, ..., E... n The elastic modulus of the first, second, ..., nth rock strata is represented by γ, which is the volumetric force of the rock strata, in units of MN / m. 3 ;γ1, γ2…γ nL represents the volumetric force of the first rock layer, the second rock layer, ..., the nth rock layer; C The center-to-center distance of the filling support is measured in meters (m).

[0026] Furthermore, the center distance L of the filling stent C The optimal parameters are determined based on the selected bracket model: 1.5m, 1.75m, 2.05m, and 2.4m.

[0027] The value of n depends on the previous rock layer no longer acting on the first rock layer. At this time, the load on the first rock layer is the load applied by the n-1 rock layer. Number of stents being filled k The calculation formula is as follows:

[0028] In the formula: Q J The amount of gangue backfilled in the well is expressed in t / a; h c The filling height is expressed in meters (m); h c =h1φ; n c represents the daily feed rate; c represents the cycle feed rate in meters; L Z The center-to-center distance of the filling stent is in meters; t is the normal circulation rate. This refers to the density of the paste, expressed in t / m³. 3 ; M 1 represents the mass concentration of gangue in the paste-like filling material, %; k This indicates the number of stents being filled. Q J The amount of gangue used for ground filling is expressed in tons per year (t / a). This refers to the density of the slurry, expressed in t / m³. 3 ; M 2 represents the mass concentration of gangue in the slurry filling material, %; L represents the working face length; h1 represents the coal seam thickness, in meters; φ represents the filling rate, %.

[0029] The number of stents being inflated can be calculated using the above formula. k The value range is within the range where the spacing between the filling supports does not exceed L. MAX In this case, based on the lithology of the roof, if the saturated uniaxial compressive strength of the roof is >30 MPa, k Take the smaller value; if the saturated uniaxial compressive strength of the top plate is <30MPa, k Take the larger value; Example 3 Furthermore, specifically, the paste filling interval is controlled by the paste filling branch pipe 3 and the three-way valve 4. The paste filling branch pipe 3 and the three-way valve 4 are opened, and the filling paste is pumped to the flexible mold bag 5 behind the paste filling support 6 to support the collapse of the top rock layer and construct a stable slurry filling space. The paste filling process is as follows: the raw coal from the coal mining face is processed, sorted using an underground coal and gangue sorting system, and then enters the underground gangue bin 19 buffer; specifically: The raw coal from the coal mining face is transported to the upper opening of the bottom coal bunker 11 via the coal conveyor belt 8. The undersize material from the roller screen 12 enters the bottom coal bunker 11 and is transported to the surface coal washing plant for washing and separation along the mine's existing transportation system. The washed coal gangue enters the surface gangue bunker 40 for buffering. The oversize material from the roller screen 12 enters the intelligent dry separation chamber 20. The clean coal separated by the intelligent dry separator 15 returns to the bottom coal bunker 11 along the return coal conveyor belt 18. The separated gangue enters the underground gangue bunker 19 for buffering. Gangue in the underground gangue bin 19 is crushed and screened by a primary crusher 21, a secondary crusher 25, and a grading screen 26. After reaching the qualified particle size, it is stored in the finished gangue bin 28. Cement and additives are transported to the cement bin 29 and the additive bin 30. According to the proportion, the materials are fed onto the centralized feeding belt 32. The centralized feeding belt 32 transports all the filling materials to the intermittent mixer 33, where water is added and the mixture is stirred. The paste is then discharged into the filling plunger pump 34, which pumps the paste into the flexible mold bag 5 behind the paste filling support 6 at the working face. In the paste unloading process, the mass ratio of gangue, cement and water is 0.64:0.16:0.2.

[0030] Example 4 Furthermore, the slurry filling process is as follows: the gangue from the ground gangue bin 40 enters the slurry filling system 41, is processed, and then transported to the slurry filling space; specifically: Gangue is crushed by crusher 43, screened by tension screen 45, and ball-milled by ball mill 46 to produce gangue powder of qualified particle size. Water is added to form a slurry of a specific concentration, which is then used to form a slurry filling liquid. This slurry is stirred in mixing tank 39 and then flows by gravity to mud pump 38, which pumps it along slurry filling pipeline 37 to the area above the working face. Based on mine geological data, precise vertical drilling is performed into the goaf area underground to reach the slurry filling space, and filling pipelines are then installed to complete the filling. The density of the slurry filling liquid is 1.2 t / m³. 3 ~1.5t / m 3 .

[0031] Step 3: Based on the mining sequence, complete the large-scale disposal of all gangue both above and below ground in the mine.

[0032] Example 5 A certain mine has a designed production capacity of 9.0 Mt / a, adopts inclined shaft development and single-level development. The main coal seam is No. 6 coal, with a working face length of 300m, an average thickness of 4.8m, and a filling rate of 90%. The filling face has 6 cuts per day, with a cycle advance of 0.865m. The center distance of the filling supports is 1.75m, the normal cycle rate is 0.95, and the density of the paste material is 2t / m³.3 The gangue mass concentration was 64%, and the slurry density was 1.33 t / m³. 3 The coal concentration is 45%; the dip angle is 0-3°; a full-height mining process is adopted; the working system is "three-eight system" (3 days a week, 8 days a week), with 330 working days per year and coal hoisting time of 16 hours per day. The roof lithology is mainly siltstone, followed by fine-grained sandstone, with a few boreholes containing medium-grained sandstone and coarse-grained ore rocks; the compressive strength is 47MPa.

[0033] According to the product balance sheet, the mine's gangue production is 1.54 million tons per year, raw coal transportation capacity is 1704.55 tons per hour, and raw coal with a particle size of 13-100mm is 573.24 tons per hour. Based on this, the capacity of the coal conveyor belt is determined to be 3000 tons per hour, the capacity of the roller screen 12 is 3000 tons per hour, the capacity of the coal feeding belt 13 and the return coal belt 18 is 1000 tons per hour, the capacity of the material distributor 14 and the intelligent dry separator 15 is 600 tons per hour, the amount of gangue separated is 97.45 tons per hour, and the capacity of the gangue feeding belt 23 and the return gangue belt 27 is 200 tons per hour. The density of the paste filling material is 2000 kg / m³. 3 The mixer and filling pump equipment are selected as 120m. 3 / h.

[0034] The underground paste filling system can handle 514,500 tons of gangue per year, while the remaining gangue on the surface is 1,025,500 tons per year. The slurry filling system 41 has a designed capacity of 1,500,000 tons per year, with a designed net filling time of 24 hours per day. The system can process 189.39 tons of gangue per hour. The selected equipment, including the feeding belt 42, crusher 43, tension screen 45, return belt 44, and ball mill 46, has a capacity of 300 tons per hour. The density of the slurry used for filling is 1.33 tons per cubic meter. 3 The mud pump 38 has a capacity of 313.4m³. 3 / h, pulping water consumption 227.3m 3 / h. The product balance sheet is shown in Table 1; the mechanical parameters of the rock strata are shown in Table 2; Table 1 Product Balance Sheet

[0035] Table 2 Mechanical parameters of rock strata

[0036] The self-load of the first rock layer is =92kPa; The load exerted by the second rock layer on the first rock layer is =140.5 kPa; The load of the third rock layer on the first rock layer is =174.7 kPa; The load of the 4th rock layer on the 1st rock layer is =163.7 kPa; Calculations show that the load of the fourth rock layer on the first layer is less than the load of the third rock layer on the first layer, therefore the load on the first rock layer is 174.7 kPa. The center-to-center distance of the selected support is 1.75 m. Maximum number of support intervals: =16.69

[0037] Substituting the above parameters, we get 33≤k≤39; The top slab has a compressive strength of 47 MPa, therefore K Take 33, that is, there are 33 supports for paste filling in the well. During the filling operation, open the three-way valve of the filling branch pipe under the supports No. 1, 6, 11, 16...151, 156, 161 to fill the paste and construct the slurry filling space.

[0038] Example 6 The method of this invention involves the following steps: During filling, gangue from the underground gangue bin is transported to the goaf via a conveying system. The filling spacing is dynamically adjusted through paste filling branch pipes to construct a stable slurry filling space. Simultaneously, gangue from the surface gangue bin is crushed, screened, and ball-milled into a slurry, which is then pumped to the top of the working face. Based on mine geological data, precise vertical drilling is performed into the underground goaf to the top of the constructed slurry filling space, and filling pipelines are then installed to complete the filling. This invention utilizes a combined paste-slurry filling operation to achieve underground filling and disposal of all million-ton-level gangue solid waste from both above-ground and underground mines, reducing ineffective gangue transportation and mitigating environmental policy risks faced by mines. Furthermore, the combined paste-slurry operation strengthens the support for the roof, effectively reducing mine pressure and solving ecological problems such as sand and water inrush at the working face and the appearance of step-like cracks or subsidence pits on the surface.

Claims

1. A method for treating gangue using a combined paste-grout backfill under sheared roof conditions, characterized in that, The specific steps are as follows: Step 1: Obtain the mine gangue production and particle size distribution based on the coal preparation plant's product balance sheet. This information will guide the design capacity and equipment selection for the paste filling system, underground coal and gangue sorting system, and slurry filling system. Step 2: Dynamically adjust the filling spacing according to the lithology of the roof. The filling spacing is determined by controlling the number of support intervals to ensure that the grout supports the roof rock layer from collapsing and to construct a stable grout filling space. Simultaneously, the gangue from the surface gangue bin enters the grout filling system, is crushed, screened, and ball-milled into gangue powder, and is mixed with water to form grout. The grout is then mixed in a mixing tank and flows by gravity to the mud pump, which pumps it along the filling pipeline to the top of the working face. Vertical drilling is then carried out in the underground goaf area to the top of the grout filling space, and filling pipelines are laid to complete the filling. Step 3: Based on the mining sequence, complete the large-scale disposal of all gangue from the mine.

2. The method for treating gangue using a combined paste-slurry backfill under sheared roof conditions as described in claim 1, characterized in that, In step 2, the formula for calculating the maximum number of stent intervals is as follows: In the formula: L MAX The maximum number of infill support intervals is expressed in supports; h is the rock stratum thickness in meters; h1, h2…h n The thicknesses of the first, second, ..., nth rock layers are represented by: R, tensile strength of the rock layer (MPa), and elastic modulus of the rock layer (MPa). E1, E2, ..., E... n The elastic modulus of the first, second, ..., nth rock strata is represented by γ, which is the volumetric force of the rock strata, in units of MN / m. 3 ;γ1, γ2…γ n L represents the volumetric force of the first rock layer, the second rock layer, ..., the nth rock layer; C The center-to-center distance of the filling support is measured in meters (m).

3. The method for treating gangue using a combined paste-slurry backfill under sheared roof conditions as described in claim 2, characterized in that, Center distance L of filling support C Specifically, it can be any one of 1.5m, 1.75m, 2.05m, or 2.4m.

4. The method for treating gangue using a combined paste-slurry backfill under sheared roof conditions as described in claim 2, characterized in that, Number of stents being filled k The calculation formula is as follows: In the formula: Q J The amount of gangue backfilled in the well is expressed in t / a; h c The filling height is in meters (m). n c represents the daily feed rate; c represents the cycle feed rate in meters; L Z The center-to-center distance of the filling support is in meters (m). t is the normal cycle rate; This refers to the density of the paste, expressed in t / m³. 3 ; M 1 represents the mass concentration of gangue in the paste-like filling material; k This indicates the number of stents being filled. Q J The amount of gangue used for ground filling is expressed in tons per year (t / a). This refers to the density of the slurry, expressed in t / m³. 3 ; M 2 represents the mass concentration of gangue used as the slurry filling material; L represents the length of the working face. The number of stents being inflated can be calculated using the above formula. K The value range is within the range where the spacing between the filling supports does not exceed L. MAX In the case of roof lithology, if the saturated uniaxial compressive strength of the roof is >30 MPa, k takes a smaller value; if the saturated uniaxial compressive strength of the roof is <30 MPa, k takes a larger value.

5. The method for treating gangue using a combined paste-slurry backfill under sheared roof conditions as described in claim 4, characterized in that, The formula for calculating the fillable height is: h c =h1φ, where h1 is the coal seam thickness in meters; φ represents the fill rate.

6. The method for treating gangue using a combined paste-slurry backfill under sheared roof conditions as described in claim 4, characterized in that, Specifically, the filling spacing of the paste is controlled by the paste filling branch pipe and the three-way valve. When the paste filling branch pipe and the three-way valve are opened, the filling paste is pumped to the flexible mold bag behind the paste filling support to support the collapse of the top rock layer and construct a stable slurry filling space.

7. The method for treating gangue using a combined paste-slurry backfill under sheared roof conditions as described in claim 6, characterized in that, The paste filling process is as follows: Raw coal from the coal face is transported to the upper opening of the bottom coal bunker via a coal conveyor belt. The undersize material from the roller screen enters the bottom coal bunker and is transported to the surface coal washing plant for washing along the existing mine transportation system. The washed coal gangue enters the surface gangue bunker for buffering. The oversize material from the roller screen enters the intelligent dry separation chamber. The clean coal separated by the intelligent dry separator is returned to the bottom coal bunker via a return coal conveyor belt. The separated gangue enters the underground gangue bunker for buffering. The gangue in the underground gangue bunker is then processed by a primary crusher and a secondary crusher. The material is crushed and screened by a grading screen. After passing the qualified particle size, it is stored in the finished product gangue silo. Cement and additives are transported to the cement silo and additive silo respectively. The material is fed onto the centralized feeding belt according to the proportion. The centralized feeding belt transports all the filling materials to the intermittent mixer, where water is added and the mixture is stirred. The paste is discharged into the filling plunger pump, which pumps the paste into the flexible mold bag behind the paste filling support at the working face. The mass ratio of gangue, cement and water in the paste discharge is 0.64:0.16:0.

2.

8. The method for treating gangue using a combined paste-slurry backfill under sheared roof conditions as described in claim 7, characterized in that, The slurry filling process is as follows: the gangue is crushed by a crusher, screened by a tension screen, and ball-milled by a ball mill to produce gangue powder of qualified particle size. Water is added to make slurry to form slurry filling liquid. The slurry filling liquid enters the mixing tank for mixing and flows by gravity to the mud pump, which pumps it to the top of the working face along the slurry filling pipeline. Based on the mine geological data, vertical holes are precisely drilled into the goaf area underground to the top of the slurry filling space, and filling pipelines are arranged to complete the filling.

9. The method for treating gangue using a combined paste-slurry backfill under sheared roof conditions as described in claim 8, characterized in that, The density of the grout used for filling is 1.2 t / m³. 3 ~1.5t / m 3 .

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