Grouting and filling method based on multi-seam mining

Abstract

The present application provides a kind of grouting filling method based on multi-coal seam mining, the method comprises: excavating chamber in first coal seam, erect filling station in the chamber, gangue is used to make grouting liquid by the filling station;The grouting liquid is transported from the first coal seam to the caving zone, fracture zone and curved subsidence zone of the second coal seam by the grouting hole through the filling station;Wherein, the first coal seam and the second coal seam are adjacent coal seams.The present application reduces the vertical depth of drilling construction, reduces the drilling cost and grouting difficulty, maintains the stability of grouting liquid filling, improves the possibility of repeated use of filling station, without multiple underground arrangement of filling station;Shorten the length of slurry conveying pipeline, reduce the pumping distance, save power resources;Gangue grouting filling speed is fast, multiple parallel operation can be carried out, pipeline transportation is adopted, arrangement is flexible, does not affect production, ensures the production efficiency of working face.

Description

Technical Field

[0001] This invention relates to the field of coal mine ecological management technology, and in particular to a grouting and backfilling method based on multi-coal seam mining. Background Technology

[0002] After underground coal mining, the overlying rock strata gradually bend and deform. When they reach their strength limit, they will break and collapse into the goaf. In the comprehensive management of coal mining subsidence areas, grouting is usually carried out to fill the collapse zone of the coal seam, thereby weakening the dynamic hazards of the overlying rock.

[0003] Currently, grouting stations are often built on the ground, with civil engineering and steel structure construction taking up a significant amount of time and being greatly affected by seasonal weather. Because the collapse zone is far from the ground, drilling grouting holes from the surface is difficult, costly, and requires considerable depth. During the grouting and filling of the underground collapse zone through these holes, excessive pumping distances can lead to grout blockage and insufficient power; the large vertical depth of the grouting fluid's fall generates significant impact force, easily causing pipe bursts at bends between downhole risers and horizontal pipes. Summary of the Invention

[0004] This invention provides a grouting and filling method based on multi-coal seam mining, which solves the problems of high cost and difficulty in drilling and grouting from the surface to the ground in the existing technology. It realizes the arrangement of filling stations in the upper coal seam, and grouting and filling from the upper coal seam to the caving zone of the lower coal seam, thereby reducing the drilling depth, drilling cost and grouting difficulty.

[0005] This invention provides a grouting and backfilling method based on multi-coal seam mining, comprising:

[0006] A chamber is excavated in the first coal seam, and a filling station is set up in the chamber to prepare grouting fluid using gangue.

[0007] The grouting fluid is transported from the first coal seam to the collapse zone, fracture zone and tortuous subsidence zone of the second coal seam through the grouting holes via the filling station;

[0008] The first coal seam and the second coal seam are adjacent coal seams.

[0009] According to the present invention, a grouting and backfilling method based on multi-coal seam mining is provided, wherein the gangue includes gangue on the ground and / or gangue generated during the mining of the first coal seam.

[0010] According to the grouting and backfilling method based on multi-coal seam mining provided by the present invention, before the step of preparing grouting fluid using gangue at the backfilling station, the method further includes:

[0011] The gangue produced by the coal preparation plant is pushed to the receiving pit;

[0012] The gangue is loaded onto the belt conveyor by a vibrating feeder in the receiving pit;

[0013] The gangue on the belt conveyor is transferred to the jaw crusher for primary crushing via a transfer system.

[0014] The belt conveyor transports the primary crushed gangue to a roller crusher or impact crusher for secondary crushing.

[0015] A portion of the gangue after secondary crushing is transported to an overflow ball mill for grinding;

[0016] Another portion of the secondary crushed gangue and the ground gangue are transported to the filling station.

[0017] According to the present invention, a grouting and backfilling method based on multi-coal seam mining includes the following steps: preparing grouting fluid using gangue at the backfilling station.

[0018] The other portion of the secondary crushed gangue and the ground gangue are transported to the batching machine in the filling station via a chute;

[0019] Water is added to the batching machine using a clean water pump, and the batched gangue is then transported to the mixing tank.

[0020] The flow meter installed in the water pump is used to adjust the electric regulating valve to add water to the mixing tank and stir to prepare the grouting liquid.

[0021] According to the present invention, a grouting and backfilling method based on multi-coal seam mining includes the following steps: transporting the grouting fluid from the first coal seam to the collapse zone, fracture zone, and tortuous subsidence zone of the second coal seam through the grouting station via grouting holes.

[0022] The pressure at the orifice of the grouting hole is determined by an electrical contact pressure gauge installed at the orifice.

[0023] The grouting stage of the grouting hole corresponding to the pressure is determined based on the pressure at the orifice.

[0024] According to the grouting speed and grouting pressure corresponding to the grouting stage, the grouting fluid is pumped into the grouting hole by an industrial pump and transported to the collapse zone, fracture zone and tortuous subsidence zone of the second coal seam through pipelines.

[0025] The pressure at the orifice, the grouting stage, the grouting speed, and the grouting pressure are pre-correlated.

[0026] According to the grouting and backfilling method based on multi-coal seam mining provided by the present invention, the step of determining the grouting stage of the grouting hole based on the pressure at the orifice includes:

[0027] When the pressure at the orifice is greater than or equal to a preset threshold, the grouting stage of the grouting hole is grouting stopped, and the grouting speed corresponding to the grouting stage is zero.

[0028] According to the present invention, a grouting and backfilling method based on multi-coal seam mining includes the following steps: preparing grouting fluid using gangue at the backfilling station.

[0029] Based on the predetermined correspondence between the mass ratio of gangue of different particle sizes, the solid mass concentration of the grouting fluid, the sedimentation rate and the spread, the solid mass concentration of the grouting fluid corresponding to the mass ratio of gangue of different particle sizes, the preset sedimentation rate and the preset spread of the grouting fluid are found.

[0030] The filling station uses gangue to prepare grouting fluid based on the solid mass concentration of the grouting fluid as determined by the information obtained.

[0031] According to the present invention, a grouting and backfilling method based on multi-coal seam mining, prior to the step of finding the solid mass concentration of the grouting fluid corresponding to the mass ratio of gangue of different particle sizes, the solid mass concentration of the grouting fluid, the sedimentation rate, and the spread of the grouting fluid based on a predetermined correspondence between the mass ratio of gangue of different particle sizes, the solid mass concentration of the grouting fluid, the sedimentation rate, and the spread of the grouting fluid, the method further includes:

[0032] Weigh out the gangue according to the mass ratio of gangue of different particle sizes;

[0033] The gangue was taken symmetrically according to different solid material mass concentrations in the grouting fluid and mixed with water to form the grouting fluid;

[0034] The grouting fluid is transferred to a measuring cylinder to determine its volume;

[0035] The grouting fluid is allowed to stand until no more water is released, and the volume of water released from the grouting fluid is determined.

[0036] The sedimentation rate of the grouting fluid is determined based on the volume of the grouting fluid and the volume of water precipitated from the grouting fluid.

[0037] The grouting fluid is injected into the test hole, and the expansion diameter of the grouting fluid is taken as the expansion degree of the grouting fluid.

[0038] Establish the correspondence between the mass ratio of gangue with different particle sizes, the solid mass concentration of the grouting fluid, the sedimentation rate, and the spread.

[0039] The grouting and filling method based on multi-coal seam mining provided by this invention involves setting up an underground filling station in the upper coal seam, converting gangue into grouting fluid, and filling the lower coal seam with the grouting fluid through drilling holes. This reduces the vertical depth of drilling, lowers drilling costs and grouting difficulty, maintains the stability of grout filling, and increases the possibility of reusing the filling station, eliminating the need for multiple underground filling station setups. It also shortens the length of slurry delivery pipelines, reduces pumping distance, and saves power resources. The gangue grouting and filling speed is fast, allowing for multiple parallel operations. The pipeline transportation method offers flexible layout, does not affect production, and ensures the production efficiency of the working face. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0041] Figure 1 This is a schematic flowchart of the grouting and backfilling method based on multi-coal seam mining provided by the present invention.

[0042] Figure 2 This is a schematic diagram of the arrangement of drilling and grouting from the upper coal seam to the lower coal seam in the grouting and filling method based on multi-coal seam mining provided by the present invention.

[0043] Figure label:

[0044] 201: Gangue pile; 202: Conveyor; 203: Crusher; 204: Water storage tank; 205: Mixer; 206: Upper coal seam; 207: Filling pipeline; 208: Lower coal seam; 209: Collapse zone; 210: Roof strata; 211: Floor strata. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0046] The following is combined with Figure 1 The present invention describes a grouting and backfilling method based on multi-coal seam mining, comprising:

[0047] Step 101: Excavate a chamber in the first coal seam, set up a filling station in the chamber, and use gangue to make grouting fluid through the filling station;

[0048] The first coal seam is the upper coal seam among two adjacent coal seams.

[0049] In the working face of the upper coal seam, chambers are excavated, and modular, simplified, and miniaturized filling stations are placed underground. This fully utilizes the large amount of abandoned goaf and roadway space underground, employing gangue filling as a method. Coal mining generates a large volume of gangue, which presents difficulties in disposal. Using gangue to form grout for underground filling enables large-scale disposal of gangue.

[0050] Optionally, the crushed gangue from the ground can be transported to a filling station located in the upper coal seam, mixed with water, and then pumped into the lower coal seam to form a qualified slurry.

[0051] The main factors influencing the design of a gangue filling slurry preparation and conveying system include the slurry preparation capacity of the slurry preparation station, the properties of the gangue slurry materials, and the conveying distance and route. The slurry preparation capacity directly affects the equipment selection in the preparation and conveying system; the properties of the gangue slurry materials include conveying performance, particle size, and proportion optimization; the conveying distance and route involve pipeline selection, conveying pressure, and the location of the slurry preparation station.

[0052] Step 102: The grouting fluid is transported from the first coal seam to the caving zone, fracture zone and tortuous subsidence zone of the second coal seam through the grouting hole via the filling station;

[0053] The first coal seam and the second coal seam are adjacent coal seams.

[0054] The second coal seam is the lower coal seam among two adjacent coal seams. Grouting holes are drilled from the upper coal seam to the caving zone, fracture zone, and bending subsidence zone of the lower coal seam.

[0055] A schematic diagram of the drilling and grouting layout from the upper coal seam to the lower coal seam in multi-coal seam mining is shown below. Figure 2 As shown, the grouting fluid prepared in the filling station is passed through the filling pipeline 207 in the grouting hole through the roof rock layer 210 and the floor rock layer 211 of the upper coal seam 206, and filled into the caving zone 209 of the lower coal seam 208, thereby weakening the overburden dynamic disaster caused by coal mining.

[0056] The arrangement of grouting holes takes into account the size of the subsequent space in the lower coal seam and the diffusion range of the gangue filling grout. The first borehole should be located at the location with the largest subsequent space in the lower coal seam to ensure the maximum amount of gangue processed in the early stage. The borehole spacing is set based on the diffusion range of the filling grout to maximize the utilization rate of the subsequent space in the lower coal seam and ensure the gangue processing capacity.

[0057] The height of the grouting layer affects the size of the subsequent space under the coal seam when the gangue slurry is filled. When the grouting layer is low, the gangue slurry can only be injected into the goaf of the working face, and the available subsequent space is small; while when the grouting layer is high, the gangue slurry can be injected into the caving zone, fracture zone and the pores and fractures therein, which can make full use of the subsequent space and maximize the treatment of gangue.

[0058] The higher the grouting pressure of the filling pump, the wider the diffusion range of the gangue slurry in the fractures, and the larger the injection volume per hole. At the same time, it can also open up some small fractures and inject slurry, making full use of the subsequent space of the lower coal seam. However, the determination of the grouting pressure also needs to consider factors such as the bearing capacity of the filling pipeline and the capacity of the filling pump. A reasonable grouting pressure needs to be selected according to the actual situation of the project.

[0059] The process of conveying gangue slurry includes drilling layout, pipeline laying and fixing, pipeline inspection before grouting, and pumping of gangue slurry.

[0060] The transport performance of filling slurry provides an important basis for the selection of material proportions, pipeline design and effect monitoring in grouting and filling projects.

[0061] This embodiment involves setting up an underground filling station in the upper coal seam to convert gangue into grouting fluid. The grouting fluid is then filled into the lower coal seam through drilling, thereby reducing the vertical depth of drilling, lowering drilling costs and grouting difficulty, maintaining the stability of grout filling, increasing the possibility of reusing the filling station, and eliminating the need for multiple underground filling station setups. It also shortens the length of the slurry delivery pipeline, reduces pumping distance, and saves power resources. The gangue grouting filling speed is fast, allowing for multiple parallel operations. The pipeline delivery method provides flexible layout, does not affect production, and ensures the production efficiency of the working face.

[0062] Based on the above embodiments, the gangue in this embodiment includes gangue on the ground and / or gangue generated during the mining of the first coal seam.

[0063] After the gangue on the ground is crushed, it is transported to a backfilling station located in the upper coal seam. Water is added and mixed at the backfilling station to prepare grouting fluid. Alternatively, the gangue pile 201 can be conveyed by conveyor 202 to the backfilling station where a crusher 203 crushes the gangue. Water is then added to the crushed gangue through a water storage tank 204, and the mixture is stirred by a mixer 205. Figure 2 As shown.

[0064] In addition to being transported from the surface, gangue can also be generated during the mining of the upper coal seam 206, thus disposing of the gangue in the upper coal seam on-site. This eliminates the need to transport the gangue to the surface, reducing the power and manpower consumption for gangue hoisting and saving gangue transportation costs. Furthermore, by combining the backfilling of boreholes in multi-coal seam mining with the backfilling of lower horizontal coal seams, solid waste from multiple coal seams can be disposed of.

[0065] This embodiment ensures production while achieving complete underground disposal of gangue, saving on gangue discharge costs, realizing large-scale disposal and utilization of gangue, and reducing the hazards caused by coal gangue accumulation.

[0066] Based on the above embodiments, this embodiment further includes the following step before the step of preparing grouting fluid from gangue at the filling station:

[0067] The gangue produced by the coal preparation plant is pushed to the receiving pit;

[0068] Gangue mainly comes from secondary waste with no utilization value generated after coal washing and processing in coal preparation plants, with a particle size ≤200mm.

[0069] The gangue produced by the coal preparation plant is first temporarily stored in the ground gangue silo, and then transported by truck to the gangue shed of the pulping station for temporary accumulation, and then pushed to the receiving pit by a loader.

[0070] The gangue is loaded onto the belt conveyor by a vibrating feeder in the receiving pit;

[0071] The gangue on the belt conveyor is transferred to the jaw crusher for primary crushing via a transfer system.

[0072] Optionally, the particle size of the primary crushing is crushed to below 40 mm.

[0073] The belt conveyor transports the primary crushed gangue to a roller crusher or impact crusher for secondary crushing.

[0074] Optionally, the particle size of the secondary crushing is crushed to below 2 mm.

[0075] A portion of the gangue after secondary crushing is transported to an overflow ball mill for grinding;

[0076] After secondary crushing, part of the gangue is fed into an overflow ball mill for grinding, optionally to a particle size of less than 0.15 mm; the other part is fed directly into the batching machine.

[0077] Another portion of the secondary crushed gangue and the ground gangue are transported to the filling station. The gangue is transported over long distances by mixing coarse and fine-grained gangue and adjusting the particle size distribution.

[0078] Based on the above embodiments, the step of preparing grouting fluid using gangue at the filling station in this embodiment includes:

[0079] The other portion of the secondary crushed gangue and the ground gangue are transported to the batching machine in the filling station via a chute;

[0080] Gangue smaller than 0.15mm enters the batching machine through a chute and is mixed with gangue smaller than 2mm and water.

[0081] Water is added to the batching machine using a clean water pump, and the batched gangue is then transported to the mixing tank.

[0082] Unlike traditional grouting methods, this embodiment uses gangue grouting material, which consists of gangue with a specific particle size distribution and a fixed amount of water, without adding other substances. The gangue grout has a high concentration, low bleeding, and good fluidity, allowing it to be injected into small voids and fissures in the goaf.

[0083] The flow meter installed in the water pump is used to adjust the electric regulating valve to add water to the mixing tank and stir to prepare the grouting liquid.

[0084] Optionally, the water volume is determined by a flow meter installed in the clean water pump, and the grout concentration is determined based on the water volume. When the grout concentration reaches a set threshold, the clean water pump is stopped by adjusting the electric regulating valve.

[0085] The filling station in this embodiment includes a receiving pit, a belt conveyor, a jaw crusher, a double-roll sand making machine, a ball mill, a batching machine, a mixing tank, an industrial pump, a water supply system, a control system, and a power supply system.

[0086] In coal mine grouting technology, the grouting materials generally used are required to have a diameter of less than 0.15 mm.

[0087] The particle size of the material affects the conveying performance of the slurry, which in turn affects the ease with which the slurry can be delivered to the target location, the smoothness of the conveying pipeline, and the subsequent expansion of the slurry in space. Therefore, it is of great importance.

[0088] The slurry conveying performance improves with the increase of fine-particle gangue content, but excessive fine-particle gangue increases grinding costs and time costs, and slows down the slurry preparation rate.

[0089] After the filling slurry is delivered to the target location, in order to provide sufficient support and control for the overlying rock strata, it is necessary to ensure that the hardness of the material is at an appropriate level. Excessive hardness of the material is not conducive to crushing and grinding.

[0090] Based on the above embodiments, the step in this embodiment of transporting the grouting fluid from the first coal seam to the collapse zone, fracture zone, and tortuous subsidence zone of the second coal seam through the grouting hole via the filling station includes:

[0091] The pressure at the orifice of the grouting hole is determined by an electrical contact pressure gauge installed at the orifice.

[0092] During the process of pumping the mixed grout into the grouting hole using an industrial pump, the pressure at the grouting hole orifice is remotely monitored using an electrical contact pressure gauge installed at the orifice.

[0093] The grouting stage of the grouting hole corresponding to the pressure is determined based on the pressure at the orifice.

[0094] As the grouting time increases, the grouting fluid compresses the air in the grouting hole, resulting in increasing pressure at the hole opening and a gradual decrease in grouting speed and pressure. The grouting process is divided into multiple stages based on the grouting phases.

[0095] According to the grouting speed and grouting pressure corresponding to the grouting stage, the grouting fluid is pumped into the grouting hole by an industrial pump and transported to the collapse zone, fracture zone and tortuous subsidence zone of the second coal seam through pipelines.

[0096] The pressure at the orifice, the grouting stage, the grouting speed, and the grouting pressure are pre-correlated.

[0097] After the grouting fluid is pumped into the grouting hole by an industrial pump, the filling slurry, equipped with a flow meter and pressure gauge, flows automatically to the three-zone area of ​​the lower level without the addition of a pumping device, without settling, segregation, or dewatering during the transportation process.

[0098] Each grouting stage corresponds to a specific grouting speed and pressure. Grouting should be performed in accordance with these speed and pressure.

[0099] Based on the above embodiments, the steps for determining the grouting stage of the grouting hole according to the pressure at the orifice in this embodiment include:

[0100] When the pressure at the orifice is greater than or equal to a preset threshold, the grouting stage of the grouting hole is grouting stopped, and the grouting speed corresponding to the grouting stage is zero.

[0101] When the pressure at the orifice is too high and exceeds the preset threshold, grouting is stopped, taking into account the bearing capacity of the grouting hole.

[0102] After grouting is stopped, continue to monitor the orifice pressure. Once the orifice pressure is below the preset threshold, continue grouting.

[0103] Based on the above embodiments, the step of preparing grouting fluid using gangue at the filling station in this embodiment includes:

[0104] Based on the predetermined correspondence between the mass ratio of gangue of different particle sizes, the solid mass concentration of the grouting fluid, the sedimentation rate and the spread, the solid mass concentration of the grouting fluid corresponding to the mass ratio of gangue of different particle sizes, the preset sedimentation rate and the preset spread of the grouting fluid are found.

[0105] For example, a ratio of coarse-grained gangue crushed to less than 2 mm and fine-grained gangue crushed to less than 0.15 mm can be used.

[0106] The finely ground gangue plays a role in water retention and suspension during the transportation of coarse-grained gangue slurry.

[0107] The sedimentation rate of the grout reflects the stone formation of the grout. The smaller the sedimentation rate, the greater the stone formation rate, and the better the stability after grouting.

[0108] The spread of grout is characterized by the diffusion radius of the grout. The larger the diffusion radius, the better the fluidity of the grout.

[0109] Through experiments, the sedimentation rate and spread of grouting fluid with different mass ratios and solid mass concentrations of two types of gangue were determined. This established the correlation between gangue mass ratio, solid mass concentration of the grouting fluid, and sedimentation rate and spread of the grouting fluid.

[0110] The concentration of the slurry directly affects its conveying performance. The conveying performance of the slurry decreases as the concentration increases, but too low a concentration will lead to a decrease in the amount of gangue processed, affecting the efficiency of the grouting project. Therefore, it is necessary to select an appropriate slurry concentration.

[0111] In this embodiment, based on actual conditions and requirements, the corresponding solid mass concentration of the grout is found after determining the gangue mass ratio, the preset sedimentation rate and the preset expansion of the grout.

[0112] The filling station uses gangue to prepare grouting fluid based on the solid mass concentration of the grouting fluid as determined by the information obtained.

[0113] The required grouting fluid is prepared by mixing the grout according to the solid mass concentration of the grouting fluid found.

[0114] For example, when the mass ratio of coarse to fine gangue is 0.5:1 and the sedimentation rate and spread meet the requirements, the optimal mix ratio is determined to be 60% solids mass concentration. In this case, coarse gangue crushed to less than 2mm accounts for 1 / 3, and fine gangue crushed to less than 0.15mm accounts for 2 / 3.

[0115] Based on the above embodiments, this embodiment further includes, before the step of finding the solid mass concentration of the grouting fluid corresponding to the mass ratio of gangue of different particle sizes, the solid mass concentration of the grouting fluid, the sedimentation rate, and the spread based on a predetermined correspondence between the mass ratio of gangue of different particle sizes, the solid mass concentration of the grouting fluid, and the spread, the following step:

[0116] Weigh out the gangue according to the mass ratio of gangue of different particle sizes;

[0117] For example, gangue can be weighed using different mass ratios of two different particle sizes.

[0118] The gangue was taken symmetrically according to different solid material mass concentrations in the grouting fluid and mixed with water to form the grouting fluid;

[0119] The grouting fluid is transferred to a measuring cylinder to determine the volume V0 of the grouting fluid;

[0120] The grouting fluid is allowed to stand until no more water is released, and the volume V of the water released from the grouting fluid is determined. i ;

[0121] The sedimentation rate R of the grouting fluid is determined based on the volume of the grouting fluid and the volume of the water precipitated from the grouting fluid. d ;

[0122] Precipitation rate R d The calculation formula is as follows:

[0123]

[0124] The grouting fluid is injected into the test hole, and the expansion diameter of the grouting fluid is taken as the expansion degree of the grouting fluid.

[0125] There are multiple test holes. Grout is injected into the test hole in the middle position. The expansion diameter of the grout is determined by observing whether grout has seeped into the other test holes.

[0126] Establish the correspondence between the mass ratio of gangue with different particle sizes, the solid mass concentration of the grouting fluid, the sedimentation rate, and the spread.

[0127] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A grouting and backfilling method based on multi-coal seam mining, characterized in that, include: A chamber is excavated in the first coal seam, and a filling station is set up in the chamber to prepare grouting fluid using gangue. The grouting fluid is transported from the first coal seam to the collapse zone, fracture zone and tortuous subsidence zone of the second coal seam through the grouting holes via the filling station; Wherein, the first coal seam and the second coal seam are adjacent coal seams; The gangue includes gangue on the ground and / or gangue generated during the mining of the first coal seam; Prior to the step of preparing grout using gangue at the filling station, the method further includes: The gangue produced by the coal preparation plant is pushed to the receiving pit; The gangue is loaded onto the belt conveyor by a vibrating feeder in the receiving pit; The gangue on the belt conveyor is transferred to the jaw crusher for primary crushing via a transfer system. The belt conveyor transports the primary crushed gangue to a roller crusher or impact crusher for secondary crushing. A portion of the gangue after secondary crushing is transported to an overflow ball mill for grinding; Another portion of the secondary crushed gangue and the ground gangue were transported to the filling station; The steps of transporting the grouting fluid from the first coal seam to the collapse zone, fracture zone, and tortuous subsidence zone of the second coal seam through the filling station include: The pressure at the orifice of the grouting hole is determined by an electrical contact pressure gauge installed at the orifice. The grouting stage of the grouting hole corresponding to the pressure is determined based on the pressure at the orifice. According to the grouting speed and grouting pressure corresponding to the grouting stage, the grouting fluid is pumped into the grouting hole by an industrial pump and transported to the collapse zone, fracture zone and tortuous subsidence zone of the second coal seam through pipelines. The pressure at the orifice, the grouting stage, the grouting speed, and the grouting pressure are pre-correlated.

2. The grouting and backfilling method based on multi-coal seam mining according to claim 1, characterized in that, The steps of preparing grouting fluid using gangue at the filling station include: The other portion of the secondary crushed gangue and the ground gangue are transported to the batching machine in the filling station via a chute; Water is added to the batching machine using a clean water pump, and the batched gangue is then transported to the mixing tank. The flow meter installed in the water pump is used to adjust the electric regulating valve to add water to the mixing tank and stir to prepare the grouting liquid.

3. The grouting and backfilling method based on multi-coal seam mining according to claim 1, characterized in that, The steps for determining the grouting stage of the grouting hole based on the pressure at the orifice include: When the pressure at the orifice is greater than or equal to a preset threshold, the grouting stage of the grouting hole is grouting stopped, and the grouting speed corresponding to the grouting stage is zero.

4. The grouting and backfilling method based on multi-coal seam mining according to any one of claims 1-3, characterized in that, The steps of preparing grouting fluid using gangue at the filling station include: Based on the predetermined correspondence between the mass ratio of gangue of different particle sizes, the solid mass concentration of the grouting fluid, the sedimentation rate and the spread, the solid mass concentration of the grouting fluid corresponding to the mass ratio of gangue of different particle sizes, the preset sedimentation rate and the preset spread of the grouting fluid are found. The filling station uses gangue to prepare grouting fluid based on the solid mass concentration of the grouting fluid as determined by the information obtained.

5. The grouting and backfilling method based on multi-coal seam mining according to claim 4, characterized in that, Before the step of finding the solid mass concentration of the grouting fluid corresponding to the mass ratio of gangue of different particle sizes, the solid mass concentration of the grouting fluid, the sedimentation rate, and the spread based on the predetermined correspondence between the mass ratio of gangue of different particle sizes, the solid mass concentration of the grouting fluid, and the spread, the method further includes: Weigh out the gangue according to the mass ratio of gangue of different particle sizes; The gangue was taken symmetrically according to different solid material mass concentrations in the grouting fluid and mixed with water to form the grouting fluid; The grouting fluid is transferred to a measuring cylinder to determine its volume; The grouting fluid is allowed to stand until no more water is released, and the volume of water released from the grouting fluid is determined. The sedimentation rate of the grouting fluid is determined based on the volume of the grouting fluid and the volume of water precipitated from the grouting fluid. The grouting fluid is injected into the test hole, and the expansion diameter of the grouting fluid is taken as the expansion degree of the grouting fluid. Establish the correspondence between the mass ratio of gangue with different particle sizes, the solid mass concentration of the grouting fluid, the sedimentation rate, and the spread.

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