Method for disposing gangue under condition of cutting-off roof with solid-sliming combined filling

Abstract

The application discloses a method for disposing gangue under a cutting-off roof by solid-slim combined filling, and is implemented through a solid-slim combined filling disposal gangue system and is as follows: screening raw coal in a working face, storing gangue in a downhole gangue storehouse after screening, and transporting the screened gangue and selected clean coal to the ground for washing and selecting, and storing the gangue in a ground gangue storehouse; dividing a goaf into a solid filling space and a slurry filling space, and spacing the two; transporting the downhole gangue storehouse gangue to the working face, dynamically adjusting gangue falling space by a multi-hole bottom unloading scraper conveyor, and tamping, so that the gangue falls into the goaf to form the solid filling space, and the solid filling spaces form the slurry filling space; preparing the ground gangue storehouse gangue into slurry, and pumping the slurry into the slurry filling space to complete the combined filling. The method solves the problems of invalid gangue transportation, limited gangue disposal capacity of solid and paste filling technologies, and the fact that the roof cannot form a filling space with mining and caving, and thus cannot fill all the gangue.

Description

Technical Field

[0001] This invention belongs to the technical field of coal mine backfilling mining methods, specifically relating to a solid-slurry combined backfilling method for treating gangue under sheared roof conditions. Background Technology

[0002] Due to the high intensity of mining, simple overburden structure, and significant impact from surface load transmission, shallow coal seam mining often exhibits strong mine pressure manifestations. The roof forms a "step-beam" structure, leading to "step subsidence" or "cut-off" collapses. Against this backdrop, coal mining faces three main challenges: First, the high mining intensity generates millions of tons of coal gangue, but the capacity for gangue resource utilization is limited, and not all gangue can be disposed of. Second, transporting such a large amount of gangue to surface coal washing plants using the mine transportation system results in significant inefficient transportation, wasting mine capacity and increasing transportation costs. Third, the roof collapses as mining progresses, leaving no overburden separation zone, and the underground goaf is largely compacted. Traditional overburden separation grouting technology and goaf slurry filling technology, primarily used for large-scale gangue disposal, are unsuitable. Solid and paste filling technologies have limited capacity to handle gangue and cannot fill all of it. Summary of the Invention

[0003] The purpose of this invention is to provide a method for treating gangue using a combined solid-grout backfilling technique under sheared roof conditions. This method solves the problem that existing solid and paste backfilling technologies have limited capacity for treating gangue and cannot completely fill all the gangue.

[0004] The technical solution adopted in this invention is a method for solid-grout combined backfilling of gangue under sheared roof conditions, implemented through a solid-grout combined backfilling system for gangue disposal, as detailed below: The raw coal at the working face is screened. The oversize material is screened and then stored as gangue in an underground gangue bin. The undersize material and the sorted clean coal are transported to the surface for washing and processing, and the gangue is stored in a surface gangue bin. The goaf is divided into solid filling space and slurry filling space, which are set alternately. Gangue from the underground gangue bin is transported to the working face. The spacing between the falling gangue is dynamically adjusted and compacted using a multi-hole bottom-discharge scraper conveyor. The gangue falls into the goaf to form solid filling spaces, and the spaces between the solid filling spaces form slurry filling spaces. The gangue from the ground gangue bin is made into slurry, which is then pumped into the slurry filling space to complete the combined filling.

[0005] The technical solution adopted in this invention is also characterized by: Furthermore, the solid-slurry combined backfilling system for treating gangue includes an underground solid backfilling subsystem, a coal and gangue sorting subsystem, and a surface slurry backfilling subsystem; The coal gangue sorting subsystem is located at the top of the coal bunker at the bottom of the mine. It screens the raw coal, and the sorted gangue enters the underground gangue bunker. The clean coal enters the coal bunker at the bottom of the mine and is transported to the surface coal washing plant for washing. The washed coal gangue enters the surface gangue bunker. The underground solid filling subsystem is located at the coal mining face. It transports gangue from the underground gangue bin into the goaf. The goaf is divided into solid filling space and slurry filling space at intervals. The spacing between the falling gangue is dynamically adjusted and compacted to form the solid filling space. A stable slurry filling space is constructed through the solid filling space, and the raw coal is transported to the coal and gangue separation subsystem. The ground slurry filling subsystem is located near the ground coal washing plant. It processes the washed coal gangue into slurry, pumps it to the area above the goaf, and inputs it into the slurry filling space.

[0006] Furthermore, the design capacity and equipment selection of the underground solid filling subsystem, coal gangue separation subsystem, and surface slurry filling subsystem are determined based on the mine gangue production and particle size distribution of the coal preparation plant.

[0007] Furthermore, the underground solid filling subsystem includes a solid filling support, which is set between the coal mining face and the goaf. Auxiliary haulage roadway and colloidal haulage roadway are respectively set at both ends of the solid filling support. A self-propelled transfer machine and a gangue conveyor belt are installed sequentially in the auxiliary transport roadway. One end of the gangue conveyor belt is connected to the underground gangue bin, and the other end is connected to the self-propelled transfer machine. The other end of the self-propelled transfer machine is connected to the perforated bottom discharge conveyor to transport the gangue to the perforated bottom discharge conveyor. A coal conveyor belt is installed in the conveyor roadway. One end of the coal conveyor belt is connected to a scraper conveyor, and the other end is set at the roller screen at the top of the coal bunker at the bottom of the shaft. A scraper conveyor is installed on the side of the solid filling support closest to the coal mining face. The scraper conveyor is connected to the coal conveying belt, which transports the raw coal to the coal and gangue separation subsystem. A multi-hole bottom-discharge conveyor is installed on the side of the solid filling support near the goaf, and several unloading holes are evenly arranged on the multi-hole bottom-discharge conveyor.

[0008] Furthermore, the coal and gangue separation subsystem includes an intelligent dry separation chamber, which is equipped with a roller screen and an intelligent dry separator. The roller screen and the intelligent dry separator are connected by a coal feeding belt and a coal return belt. The roller screen is located at the top of the coal bunker at the bottom of the shaft. Raw coal is transported to the roller screen along the coal conveyor belt. The undersize material from the roller screen enters the coal bunker at the bottom of the shaft, while the oversize material enters the intelligent dry separator via the coal feeding belt. The clean coal separated by the intelligent dry separator is returned to the coal bunker at the bottom of the shaft along the coal return belt. An underground gangue bin is located at the bottom of the intelligent dry separator, where the separated gangue is buffered. A material distributor is installed at the end of the coal conveyor belt, and auxiliary facilities for the intelligent dry separator are installed on one side of the intelligent dry separator. The outlet of the intelligent dry separator is connected to a branch chute, one end of which is connected to the return coal conveyor belt, and the other end is connected to the underground gangue bin.

[0009] Furthermore, the ground slurry filling subsystem includes a ground gangue bin and a slurry filling system connected by a feeding belt. The slurry filling system includes a crusher, a ball mill, a mixing tank, and a mud pump connected in sequence. The crusher and the ball mill are connected by a return belt. A tension screen is installed on the end of the return belt near the ball mill. The mud pump is connected to a filling pipeline and delivers gangue slurry to the area above the goaf through the filling pipeline.

[0010] Furthermore, the dynamic adjustment of the rockfall spacing includes: dynamically adjusting the filling spacing according to the lithology of the roof, increasing the spacing when the roof is hard and decreasing the spacing when the roof is weak; the filling spacing is determined by controlling the number of solid filling support intervals to ensure that the solid support supports the roof rock layer from collapsing and to construct a stable slurry filling space. The maximum number of solid-filled stents at intervals is shown in formula (1):

[0011] Where: LMAX—maximum number of filling supports, supports; h—rock stratum thickness, m; h1, h2…hn represent the thickness of the first rock stratum, the second rock stratum…the nth rock stratum; R—tensile strength of the rock stratum, MPa; E—elastic modulus of the rock stratum, MPa; E1, E2…En represent the elastic modulus of the first rock stratum, the second rock stratum…the nth rock stratum; γ—volume force of the rock stratum, MN / m3; γ1, γ2…γn represent the volume force of the first rock stratum, the second rock stratum…the nth rock stratum; LC—center-to-center distance of the filling supports, m; 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. The number of supports being filled underground is shown in formulas (2) and (3):

[0012] Where: QJ—underground gangue filling volume, t / a; hc—fillable height, m; n—number of cutters per day; c—circular footage, m; LC—center distance of filling supports, m; t—normal circulation rate; ρ1—apparent density of compacted gangue, t / m3; K—number of supports currently filling; QD—surface gangue filling volume, t / a; ρ2—slurry density, t / m3; M2—gangue mass concentration of slurry filling material, %; L—working face length; h1—coal seam thickness, m; φ—filling rate, %.

[0013] The range of values ​​for the number of infilled stents K can be calculated using the above formula, provided that the spacing between the infilled stents does not exceed L. MAXIn the case of roof lithology, if the saturated uniaxial compressive strength of the roof is >30MPa, k takes the minimum value; if the saturated uniaxial compressive strength of the roof is <30MPa, k takes the maximum value. Center distance L of filling support C The preferred parameters are 1.5m, 1.75m, 2.05m, or 2.4m, depending on the selected bracket model.

[0014] Furthermore, the process of turning the gangue from the ground silo into slurry includes: the gangue from the ground gangue silo enters the slurry filling system, is crushed, screened, and ball-milled into gangue powder of qualified particle size, and water is added to make a slurry of a specific concentration, which is then stirred in a mixing tank.

[0015] Furthermore, during the pumping of slurry, the slurry flows by gravity to the mud pump and is pumped along the filling pipeline to the top of the working face. Based on the mine geological data, vertical boreholes are precisely drilled into the goaf underground to the top of the slurry filling space, and filling pipelines are arranged to complete the filling.

[0016] Furthermore, solid filling and slurry filling are carried out simultaneously, and the above filling steps are performed cyclically to complete the filling and disposal of all gangue both above and below ground according to the mining and excavation sequence.

[0017] The beneficial effects of this invention are: 1. By utilizing a combined solid-slurry backfilling operation, all million tons of gangue solid waste from both above-ground and underground mines can be backfilled and disposed of underground, reducing ineffective gangue transportation, mitigating environmental risks faced by the mine, and eliminating the environmental impact of gangue surface accumulation on water bodies, soil, and atmosphere, as well as safety hazards such as spontaneous combustion and landslides of gangue piles.

[0018] 2. The collapse mode of the working face roof "cutting off" or "step sinking" is characterized by suddenness, penetration and strong destructive force. This invention uses a multi-hole bottom discharge conveyor to intermittently drop gangue for precise filling and control of overburden movement, timely control of roof collapse, and slurry filling to dispose of solid waste while filling the gaps of gangue solid filling, further strengthening the support of the roof, effectively reducing mine pressure, and solving ecological 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 downhole solid filling subsystem of the present invention; Figure 2 This is a schematic diagram of the coal gangue separation subsystem of the present invention; Figure 3 This is a schematic diagram of the ground slurry filling subsystem of the present invention; Figure 4 This is a schematic diagram of ground grouting for the solid-grout combined backfilling method for treating gangue under the sheared roof conditions of the present invention.

[0020] In the diagram, 1. Auxiliary transport roadway, 2. Self-propelled transfer conveyor, 3. Gangue transport belt, 4. Solid filling support, 5. Multi-hole bottom discharge conveyor, 6. Gangue discharge hole, 7. Glue transport roadway, 8. Coal transport 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 auxiliary facilities, 17. 18. Branching chute; 19. Coal return conveyor belt; 20. Underground gangue bin; 21. Intelligent dry separation chamber; 22. Surface gangue bin; 23. Slurry filling system; 24. Feeding conveyor belt; 25. Crusher; 26. Return conveyor belt; 27. Tension screen; 28. Ball mill; 29. ​​Mixing tank; 30. Slurry pump; 11. Filling pipeline; 22. Solid filling space; 23. Slurry filling space; 34. Coal mining face. Detailed Implementation

[0021] The present invention will be further illustrated below through examples.

[0022] This invention provides a method for solid-grout combined backfilling to dispose of gangue under sheared roof conditions, comprising 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 underground solid filling subsystem, coal gangue separation subsystem and surface slurry filling subsystem; An underground solid backfilling subsystem is deployed at the coal mining face in a coal mine, such as... Figure 1 As shown, the downhole solid filling subsystem mainly consists of a gangue conveyor belt 3, a self-propelled transfer machine 2, a solid filling support 4, and a multi-hole bottom-discharge conveyor 5; Step 2: As Figure 2 As shown, a roller screen 12 is installed at the top of the coal bunker 11 at the bottom of the shaft. Nearby is an intelligent dry separation chamber 20, within which are arranged sequentially a coal conveyor belt 13, a material distributor 14, an intelligent dry separator 15, auxiliary facilities for the intelligent dry separator 16, a return coal conveyor belt 18, and an underground gangue bunker 19. Figure 3 As shown, a ground gangue silo 21 and a slurry filling system 22 are arranged near the ground coal washing plant. The slurry filling system 22 mainly consists of a feeding belt 23, a crusher 24, a tension screen 26, a return belt 25, a ball mill 27, a mixing tank 28, a mud pump 29, and a filling pipeline 30.

[0023] Step 3: The raw coal from the working face is transported to the upper roller screen 12 of the bottom coal bunker 11. The undersize material enters the bottom coal bunker 11 and is transported to the surface coal washing plant for washing and beneficiation along the original mine transportation system. The washed coal gangue enters the surface gangue bunker 21 for buffering. The oversize material enters the intelligent dry separation chamber 20. The clean coal separated by the intelligent dry separator 15 is returned to the bottom coal bunker 11 along the return coal conveyor belt 18. The separated gangue enters the underground gangue bunker 19 for buffering.

[0024] Step 4: During the filling operation, the underground gangue bin 19 places gangue onto the gangue transport belt 3, which then transports the gangue to the underground solid filling subsystem. The perforated bottom-discharge conveyor 5 dynamically adjusts the gangue dropping spacing according to the roof lithology; when the roof is relatively hard, the dropping spacing is appropriately increased; when the roof is relatively soft, the dropping spacing is appropriately decreased. The filling spacing is dynamically adjusted according to the lithology of the roof. The spacing is increased when the roof is hard and decreased when the roof is soft. The filling spacing is determined by controlling the number of solid filling supports at intervals of 4 to ensure that the solid support can withstand the collapse of the roof rock layer and construct a stable grout filling space. The maximum number of solid-filled stents 4 is shown in formula (1):

[0025] In the formula: L MAX —Maximum number of filling supports, supports; h—Roof layer thickness, m; h1, h2…hn represent the thickness of the first, second…nth rock layer; R—Tensile strength of the rock layer, MPa; E—Elastic modulus of the rock layer, MPa; E1, E2…En represent the elastic modulus of the first, second…nth rock layer; γ—Rock layer volumetric force, MN / m3; γ1, γ2…γn represent the volumetric force of the first, second…nth rock layer; L C —Center-to-center distance of the filling support, m; 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. The number of supports being filled underground is shown in formulas (2) and (3):

[0026] Where: QJ—downhole gangue filling volume, t / a; hc—fillable height, m; n—number of cutters per day; c—circular footage, m; LZ—center distance of filling supports, m; t—normal circulation rate; ρ1—apparent density of compacted gangue, t / m³ 3 K—Number of supports being filled; QD—Amount of gangue filling on the ground, t / a; ρ2—Density of slurry, t / m3; M2—Mass concentration of gangue in slurry filling material, %; L—Length of working face; h1—Thickness of coal seam, m; φ—Filling rate, %.

[0027] The range of values ​​for the number of downhole filling supports K is calculated using the above formula. When the spacing between filling supports does not exceed LMAX, based on the roof lithology, if the saturated uniaxial compressive strength of the roof is >30MPa, k takes a smaller value; if the saturated uniaxial compressive strength of the roof is <30MPa, k takes a larger value. Furthermore, the center distance LZ of the filling support is determined according to the selected support model, with preferred parameters being 1.5m, 1.75m, 2.05m, and 2.4m.

[0028] After the gangue is intermittently dumped into the goaf, it is compacted to support the collapse of the roof strata, forming solid filling space I and constructing a stable slurry filling space II. Simultaneously, gangue from the surface gangue bin 21 enters the slurry filling system, is crushed, screened, and ball-milled into gangue powder of qualified particle size, and is mixed with water to form a slurry of a specific concentration, which is then stirred in the mixing tank 28 and flows by gravity to the mud pump 29, which pumps it along the filling pipeline 30 to the area above the coal face III. Figure 4 As shown, based on the mine geological data, a vertical borehole was precisely drilled into the underground goaf area to the top of the slurry filling space II, and a filling pipe 30 was laid to complete the filling.

[0029] Step 5: Based on the mining sequence, complete the large-scale disposal of all gangue both above and below ground in the mine.

[0030] The following will provide further explanation using specific implementation examples.

[0031] Example 1 The method for solid-grout combined backfilling of gangue under sheared roof conditions is implemented through a solid-grout combined backfilling system, as detailed below: The raw coal at the working face is screened. The oversize material is screened and then stored as gangue in an underground gangue bin. The undersize material and the sorted clean coal are transported to the surface for washing and processing, and the gangue is stored in a surface gangue bin. The goaf is divided into solid filling space and slurry filling space, which are set alternately. Gangue from the underground gangue bin is transported to the working face. The spacing between the falling gangue is dynamically adjusted and compacted using a multi-hole bottom-discharge scraper conveyor. The gangue falls into the goaf to form solid filling spaces, and the spaces between the solid filling spaces form slurry filling spaces. The gangue from the ground gangue bin is made into slurry, which is then pumped into the slurry filling space to complete the combined filling.

[0032] The solid-slurry combined backfilling system for treating gangue includes an underground solid backfilling subsystem, a coal and gangue sorting subsystem, and a surface slurry backfilling subsystem; The underground solid filling subsystem is located in the coal mining face III. It transports gangue into the goaf, dynamically adjusts the spacing between the falling gangue and compacts it to construct a stable slurry filling space III, and transports raw coal to the coal and gangue sorting subsystem. The coal gangue sorting subsystem is located at the top of the bottom coal bunker 11 to screen the raw coal. The sorted gangue enters the underground gangue bunker 19, while the clean coal enters the bottom coal bunker 11 and is transported to the surface coal washing plant for washing. The washed coal gangue enters the surface gangue bunker 21. The ground slurry filling subsystem is located near the ground coal washing plant. It processes the washed coal gangue into slurry and pumps it to the area above the goaf.

[0033] Example 2 The method for solid-grout combined backfilling of gangue under sheared roof conditions is implemented through a solid-grout combined backfilling system, as detailed below: The raw coal at the working face is screened. The oversize material is screened and then stored as gangue in an underground gangue bin. The undersize material and the sorted clean coal are transported to the surface for washing and processing, and the gangue is stored in a surface gangue bin. The goaf is divided into solid filling space and slurry filling space, which are set alternately. Gangue from the underground gangue bin is transported to the working face. The spacing between the falling gangue is dynamically adjusted and compacted using a multi-hole bottom-discharge scraper conveyor. The gangue falls into the goaf to form solid filling spaces, and the spaces between the solid filling spaces form slurry filling spaces. The gangue from the ground gangue bin is made into slurry, which is then pumped into the slurry filling space to complete the combined filling.

[0034] The solid-slurry combined backfilling system for treating gangue includes an underground solid backfilling subsystem, a coal and gangue sorting subsystem, and a surface slurry backfilling subsystem; The underground solid filling subsystem is located in the coal mining face III. It transports gangue into the goaf, dynamically adjusts the spacing between the falling gangue and compacts it to construct a stable slurry filling space III, and transports raw coal to the coal and gangue sorting subsystem. The coal gangue sorting subsystem is located at the top of the bottom coal bunker 11 to screen the raw coal. The sorted gangue enters the underground gangue bunker 19, while the clean coal enters the bottom coal bunker 11 and is transported to the surface coal washing plant for washing. The washed coal gangue enters the surface gangue bunker 21. The ground slurry filling subsystem is located near the ground coal washing plant. It processes the washed coal gangue into slurry and pumps it to the area above the goaf.

[0035] The underground solid filling subsystem includes a solid filling support 4, which is located between the coal mining face and the goaf. Auxiliary transport roadway 1 and a colloid transport roadway 7 are respectively located at both ends of the solid filling support 4. A self-propelled transfer machine 2 and a gangue conveyor belt 3 are installed sequentially in the auxiliary transport roadway 1. One end of the gangue conveyor belt 3 is connected to the underground gangue bin 19, and the other end is connected to the self-propelled transfer machine 2. The other end of the self-propelled transfer machine 2 is connected to the perforated bottom discharge conveyor 5 to transport gangue to the perforated bottom discharge conveyor 5. A coal conveyor belt 8 is installed in the conveyor roadway 7. One end of the coal conveyor belt 8 is connected to the scraper conveyor 10, and the other end is installed at the roller screen 12 at the top of the coal bunker 11 at the bottom of the shaft. A scraper conveyor 10 is installed on the side of the solid filling support 4 near the coal mining face. The scraper conveyor 10 is connected to the coal conveying belt 8 and transports the raw coal to the coal gangue separation subsystem via the coal conveying belt 8. A multi-hole bottom-discharge conveyor 5 is installed on the side of the solid filling support 4 near the goaf, and several unloading holes 6 are evenly arranged on the multi-hole bottom-discharge conveyor 5.

[0036] The coal and gangue separation subsystem includes an intelligent dry separation chamber 20, and also includes a roller screen 12 and an intelligent dry separator 15 installed in the intelligent dry separation chamber 20. The roller screen 12 and the intelligent dry separator 15 are connected by a coal feeding belt 13 and a coal return belt 18. The roller screen 12 is arranged at the top of the bottom coal bunker 11. Raw coal is transported to the roller screen 12 along the coal conveying belt 8. The undersize material of the roller screen 12 enters the bottom coal bunker 11, and the oversize material enters the intelligent dry separator 15 through the coal feeding belt 13. The clean coal separated by the intelligent dry separator 15 is returned to the bottom coal bunker 11 along the coal return belt 18. An underground gangue bin 19 is set at the bottom of the intelligent dry separator 15, and the separated gangue enters the underground gangue bin 19 for buffering. A material distributor 14 is installed at the end of the coal conveyor belt 13, and an auxiliary facility 16 for the intelligent dry separator 15 is installed on one side of the intelligent dry separator 15. The outlet of the intelligent dry separator 15 is connected to a branch chute 17, one end of which is connected to the return coal conveyor belt 18, and the other end is connected to the underground gangue bin 19.

[0037] The ground slurry filling subsystem includes a ground gangue bin 21 and a slurry filling system 22 connected by a feeding belt 23. The slurry filling system 22 includes a crusher 24, a ball mill 27, a mixing tank 28 and a mud pump 29 connected in sequence. The crusher 24 and the ball mill 27 are connected by a return belt 25. A tension screen 26 is installed on the return belt 25 near the ball mill 27. The mud pump 29 is connected to a filling pipe 30 and sends gangue slurry to the area above the goaf through the filling pipe 30.

[0038] Example 3 Based on Example 2, a method for solid-grout combined backfilling of gangue under sheared roof conditions includes: Dynamic adjustment of rockfall spacing includes: dynamically adjusting the filling spacing according to the lithology of the roof, increasing the spacing when the roof is hard and decreasing the spacing when the roof is soft; the filling spacing is determined by controlling the number of solid filling supports 4 intervals to ensure that the solid supports the roof rock layer from collapsing and to construct a stable slurry filling space. The maximum number of solid-filled stents 4 is shown in formula (1):

[0039] Where: LMAX—maximum number of filling supports, supports; h—rock stratum thickness, m; h1, h2…hn represent the thickness of the first rock stratum, the second rock stratum…the nth rock stratum; R—tensile strength of the rock stratum, MPa; E—elastic modulus of the rock stratum, MPa; E1, E2…En represent the elastic modulus of the first rock stratum, the second rock stratum…the nth rock stratum; γ—volume force of the rock stratum, MN / m3; γ1, γ2…γn represent the volume force of the first rock stratum, the second rock stratum…the nth rock stratum; LC—center-to-center distance of the filling supports, m; 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. The number of supports being filled underground is shown in formulas (2) and (3):

[0040] Where: QJ—underground gangue filling volume, t / a; hc—fillable height, m; n—number of cutters per day; c—circular footage, m; LC—center distance of filling supports, m; t—normal circulation rate; ρ1—apparent density of compacted gangue, t / m3; K—number of supports currently filling; QD—surface gangue filling volume, t / a; ρ2—slurry density, t / m3; M2—gangue mass concentration of slurry filling material, %; L—working face length; h1—coal seam thickness, m; φ—filling rate, %.

[0041] The range of values ​​for the number of infilled stents K can be calculated using the above formula, provided that the spacing between the infilled stents does not exceed L. MAX In the case of roof lithology, if the saturated uniaxial compressive strength of the roof is >30MPa, k takes the minimum value; if the saturated uniaxial compressive strength of the roof is <30MPa, k takes the maximum value. Center distance L of filling support C The preferred parameters are 1.5m, 1.75m, 2.05m, or 2.4m, depending on the selected bracket model.

[0042] Example 4 Based on Example 3, the dynamic adjustment of the rockfall spacing includes: increasing the spacing when the top plate is hard and decreasing the spacing when the top plate is soft.

[0043] The lithology of a certain roof is as follows:

[0044] 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. Number of support intervals =16.69

[0045] Substituting the parameters above, we get 21≤k≤39. The top plate has a compressive strength of 25MPa, so K is taken as 39, which means that there are 39 supports being filled. During the filling operation, the multi-hole bottom discharge conveyor discharge holes of supports No. 1, 5, 9, 13...141, 145, 149, 153 are opened to construct the slurry filling space.

[0046] The process of turning gangue from ground silos into slurry includes: the gangue from the ground gangue silos enters the slurry filling system, is crushed, screened, and ball-milled into gangue powder of qualified particle size, and water is added to make slurry of a specific concentration, which is then stirred in a mixing tank.

[0047] Example 5 Based on Example 4, the process of making slurry from ground gangue includes: the gangue from the ground gangue silo enters the slurry filling system, is crushed, screened, and ball-milled to make gangue powder of qualified particle size, and water is added to make slurry of a specific concentration, which is then stirred in a mixing tank.

[0048] When pumping slurry, the slurry flows by gravity to the mud pump and is pumped to the top of the working face along the filling pipeline. Based on the mine geological data, vertical boreholes are precisely drilled into the goaf underground to the top of the slurry filling space, and filling pipelines are arranged to complete the filling.

[0049] Solid filling and slurry filling are carried out simultaneously.

[0050] The filling process is repeated cyclically to complete the filling of all gangue both above and below ground, according to the mining sequence.

[0051] Example 6 A certain mine has a designed production capacity of 9.0 Mt / a, employing inclined shaft and single-level development methods. 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-to-center distance of the filling supports is 1.75m, and the normal cycle rate is 0.95. The apparent density of the compacted gangue is 2t / m³. 3 The slurry density is 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 25MPa.

[0052] 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 intelligent 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 self-propelled transfer conveyor 2 and the gangue conveyor belt 3 is 300 tons per hour.

[0053] The downhole solid filling subsystem 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 22 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 handle 189.39 tons of gangue per hour. The selected equipment, including the feeding conveyor belt 23, crusher 24, tension screen 26, return conveyor belt 25, and ball mill 27, has a capacity of 300 tons per hour. The mud pump 29 has a capacity of 313.4 m³. 3 / h, pulping water consumption 227.3m 3 / h.

[0054] Table 1 Product Balance Sheet

[0055] Step 1: An underground solid filling subsystem is arranged in the coal mining face III of the coal mine. The underground solid filling subsystem includes a solid filling support 4, a multi-hole bottom discharge conveyor 5, a coal mining machine 9, and a scraper conveyor 10. The multi-hole bottom discharge conveyor 5 is uniformly provided with several continuously arranged unloading holes 6. A self-propelled transfer machine 2 and a coal transport belt 3 are arranged in the auxiliary transport roadway 1, and a coal transport belt 8 is arranged in the conveyor roadway 7. A roller screen 12 is arranged at the top of the bottom coal bunker 11. An intelligent dry separation chamber 20 is excavated near the bottom coal bunker 11. Inside the intelligent dry separation chamber 20, a coal conveyor belt 13, a material distributor 14, an intelligent dry separator 15, and auxiliary facilities 16 for the intelligent dry separator are arranged. A bifurcated chute 17 is connected below the intelligent dry separator 15. One end of the bifurcated chute 17 is connected to the return coal conveyor belt 18, and the other end is connected to the underground gangue bunker 19. A surface gangue bunker 21 and a slurry filling system 22 are arranged near the surface coal washing plant. The slurry filling system 22 mainly consists of a feeding belt 23, a crusher 24, a return belt 25, a tension screen 26, a ball mill 27, a mixing tank 28, a mud pump 29, and a filling pipeline 30. The production and particle size distribution of mine gangue are determined by the product balance sheet of the coal preparation plant, which is used to accurately guide the capacity design and equipment selection of the solid filling subsystem, coal gangue separation subsystem and surface slurry filling subsystem.

[0056] Step 2: The raw coal cut by the coal mining machine 9 is transported along the scraper conveyor 10 and the coal conveyor belt 8 to the roller screen 12 located above the bottom coal bunker 11. The undersize material from the roller screen 12 enters the bottom coal bunker 11 and is transported along the mine's existing transportation system to the surface coal washing plant for washing and separation. The washed coal gangue enters the surface gangue bunker 21 for buffering. The oversize material enters the intelligent dry separation chamber 20. The clean coal separated by the intelligent dry separator 15 is returned to the bottom coal bunker 11 along the return coal conveyor belt 18, and the separated gangue enters the underground gangue bunker 19 for buffering.

[0057] Step 3: During the filling operation, the gangue bin 19 underground is fed out by the feeder. The gangue is transported along the gangue conveyor belt 3 and the self-propelled transfer conveyor 2 to the multi-hole bottom discharge conveyor 5 suspended behind the solid filling support 4. like Figure 1 As shown, the spacing of the falling gangue is controlled by the unloading hole 6. The unloading holes of the multi-hole bottom-discharge conveyor of supports No. 1, 5, 9, 13...141, 145, 149, 153 are opened. The gangue is dropped intermittently into the goaf and then compacted to support the collapse of the rock strata. The slurry filling space II is constructed. Simultaneously, the gangue in the gangue bin 21 on the ground enters the slurry filling system 22. After being crushed, screened and ball-milled to a qualified particle size, water is added to make a slurry of a specific concentration, which is then stirred in the slurry mixing tank and flows by gravity to the mud pump 29 and pumped to the top of the working face along the filling pipeline 30. Based on the mine geological data, vertical drilling is precisely constructed into the goaf underground to the top of the slurry filling space II, and the filling pipeline is arranged to complete the filling.

[0058] Step 5: According to the mining sequence, complete the backfilling and disposal of all gangue in and around the mine.

Claims

1. A method for solid-grout combined backfilling of gangue under sheared roof conditions, characterized in that, The waste rock disposal system is implemented through a combined solid-slurry backfilling method, as detailed below: The raw coal at the working face is screened. The oversize material is screened and then stored as gangue in an underground gangue bin. The undersize material and the sorted clean coal are transported to the surface for washing and processing, and the gangue is stored in a surface gangue bin. The goaf is divided into solid filling space and slurry filling space, which are set alternately. Gangue from the underground gangue bin is transported to the working face. The spacing between the falling gangue is dynamically adjusted and compacted using a multi-hole bottom-discharge scraper conveyor. The gangue falls into the goaf to form solid filling spaces, and the spaces between the solid filling spaces form slurry filling spaces. The gangue from the ground gangue bin is made into slurry and pumped into the slurry filling space to complete the joint filling; The solid-slurry combined backfilling system for treating gangue includes an underground solid backfilling subsystem, a coal and gangue sorting subsystem, and a surface slurry backfilling subsystem. The coal gangue sorting subsystem is located at the top of the coal bunker at the bottom of the mine. It screens the raw coal, and the sorted gangue enters the underground gangue bunker. The clean coal enters the coal bunker at the bottom of the mine and is transported to the surface coal washing plant for washing. The washed coal gangue enters the surface gangue bunker. The underground solid filling subsystem is located at the coal mining face. It transports gangue from the underground gangue bin into the goaf. The goaf is divided into solid filling space and slurry filling space at intervals. The spacing between the falling gangue is dynamically adjusted and compacted to form the solid filling space. A stable slurry filling space is constructed through the solid filling space, and the raw coal is transported to the coal and gangue separation subsystem. The ground slurry filling subsystem is located near the ground coal washing plant. It turns the washed coal gangue into slurry, pumps it to the top of the goaf, and inputs it into the slurry filling space. The underground solid filling subsystem includes a solid filling support (4), which is installed between the coal mining face and the goaf. The dynamic adjustment of the rockfall spacing includes: dynamically adjusting the filling spacing according to the lithology of the roof, increasing the spacing when the roof is hard and decreasing the spacing when the roof is soft; the filling spacing is determined by controlling the number of solid filling supports (4) to ensure that the solid supports the roof strata collapse and construct a stable slurry filling space. The maximum number of intervals for solid-filled stents (4) is shown in formula (1): In the formula: L MAX —Maximum number of infill support intervals, supports; h—Rock stratum thickness, m; h1, h2…h n Represents the thickness of the first, second, ..., nth rock layer; R—tensile strength of the rock layer, MPa; E—elastic modulus of the rock layer, MPa; E1, E2...E n Represents the elastic modulus of the first, second, ..., nth rock layer; γ—the volumetric force of the rock layer, 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 —Center-to-center distance of the filling support, m; 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. The number of supports being filled underground is shown in formulas (2) and (3): In the formula: Q J —Downhole gangue backfill volume, t / a; h c — Filling height, m; n— Number of feeds per day; c— Cycle feed, m; L C — Center-to-center distance of filling supports, m; t— Normal circulation rate; ρ1— Apparent density of compacted gangue, t / m³ 3 K—Number of stents being filled; Q D —Ground gangue backfill volume, t / a, ρ2—Slurry density, t / m³ 3 M2—Mass concentration of gangue in slurry filling material, %; L—Length of working face; h1—Thickness of coal seam, m; φ—Filling rate, % The range of values ​​for the number of stents K being inflated can be calculated using the above formula, provided that the spacing between the inflated stents does not exceed L. MAX In the case of roof lithology, if the saturated uniaxial compressive strength of the roof is >30MPa, k takes the minimum value; if the saturated uniaxial compressive strength of the roof is <30MPa, k takes the maximum value. Center distance L of filling support C The dimensions are determined based on the selected bracket model, and the parameters are 1.5m, 1.75m, 2.05m, or 2.4m.

2. The method for solid-grout combined backfilling of gangue under sheared roof conditions according to claim 1, characterized in that, The design capacity and equipment selection of the underground solid filling subsystem, coal gangue separation subsystem, and surface slurry filling subsystem are determined based on the mine gangue production and particle size distribution of the coal preparation plant.

3. The method for solid-grout combined backfilling of gangue under sheared roof conditions according to claim 2, characterized in that, The solid filling support (4) is provided with an auxiliary transport chute (1) and an adhesive transport chute (7) at both ends. A self-propelled transfer machine (2) and a gangue conveyor belt (3) are installed sequentially in the auxiliary transport roadway (1). One end of the gangue conveyor belt (3) is connected to the underground gangue bin (19), and the other end is connected to the self-propelled transfer machine (2). The other end of the self-propelled transfer machine (2) is connected to the perforated bottom discharge conveyor (5) to transport the gangue to the perforated bottom discharge conveyor (5). A coal conveyor belt (8) is installed in the conveyor roadway (7). One end of the coal conveyor belt (8) is connected to a scraper conveyor (10), and the other end is set at the upper opening of the coal bunker (11) at the bottom of the shaft. A scraper conveyor (10) is installed on the side of the solid filling support (4) near the coal mining face. The scraper conveyor (10) is connected to the coal conveying belt (8) to transport the raw coal to the coal gangue sorting subsystem via the coal conveying belt (8). A multi-hole bottom discharge conveyor (5) is installed on the side of the solid filling support (4) near the goaf, and several unloading holes (6) are evenly arranged on the multi-hole bottom discharge conveyor (5).

4. The method for solid-grout combined backfilling of gangue under sheared roof conditions according to claim 3, characterized in that, The coal and gangue separation subsystem includes an intelligent dry separation chamber (20), in which a roller screen (12) and an intelligent dry separator (15) are installed. The roller screen (12) and the intelligent dry separator (15) are connected by a coal conveyor belt (13) and a return coal conveyor belt (18). The roller screen (12) is arranged at the top of the bottom coal bunker (11). The raw coal is transported to the roller screen (12) along the coal conveyor belt (8). The undersize material of the roller screen (12) enters the bottom coal bunker (11), and the oversize material enters the intelligent dry separator (15) through the coal conveyor belt (13). The clean coal separated by the intelligent dry separator (15) returns to the bottom coal bunker (11) along the return coal conveyor belt (18). An underground gangue bunker (19) is set at the bottom of the intelligent dry separator (15). The separated gangue enters the underground gangue bunker (19) for buffering. A material distributor (14) is installed at the end of the coal conveyor belt (13), and an auxiliary facility (16) for the intelligent dry separator (15) is installed on one side. The outlet of the intelligent dry separator (15) is connected to a branch chute (17). One end of the branch chute (17) is connected to the return coal conveyor belt (18), and the other end is connected to the underground gangue bin (19).

5. The method for solid-grout combined backfilling of gangue under sheared roof conditions according to claim 4, characterized in that, The ground slurry filling subsystem includes a ground gangue bin (21) and a slurry filling system (22) connected by a feeding belt (23). The slurry filling system (22) includes a crusher (24), a ball mill (27), a mixing tank (28), and a mud pump (29) connected in sequence. The crusher (24) and the ball mill (27) are connected by a return belt (25). A tension screen (26) is provided on one end of the return belt (25) near the ball mill (27). The mud pump (29) is connected to a filling pipe (30) and the gangue slurry is sent to the area above the goaf through the filling pipe (30).

6. The method for solid-grout combined backfilling of gangue under sheared roof conditions according to claim 5, characterized in that, The process of turning gangue from ground silos into slurry includes: the gangue from the ground gangue silos enters the slurry filling system, is crushed, screened, and ball-milled into gangue powder of qualified particle size, and water is added to make slurry of a specific concentration, which is then stirred in a mixing tank.

7. The method for solid-grout combined backfilling of gangue under sheared roof conditions according to claim 6, characterized in that, When pumping slurry, the slurry flows by gravity to the mud pump and is pumped to the top of the working face along the filling pipeline. Based on the mine geological data, vertical boreholes are precisely drilled into the goaf underground to the top of the slurry filling space, and filling pipelines are arranged to complete the filling.

8. The method for solid-grout combined backfilling of gangue under sheared roof conditions according to claim 7, characterized in that, The solid filling and slurry filling are carried out simultaneously, and the filling steps are performed cyclically to complete the filling and disposal of all gangue both above and below ground according to the mining and excavation sequence.

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