Drainage grouting absorption method for gangue in lower space of rear suspension roof of coal mine frame

Abstract

The invention discloses a drainage, grouting and absorption method for gangue in the lower space of a rear suspension roof of a coal mine frame, and belongs to the technical field of green mining of coal mines. After raw coal is mined underground, the raw coal is conveyed into an underground screening-intelligent gangue selection-crushing-stirring-grouting comprehensive operation chamber through a transfer belt, and the raw coal is conveyed into a slurry storage tank through an industrial filling pump; injecting the prepared gangue slurry into a space formed by coal mining; the gangue slurry is conveyed to the position close to the fully-mechanized mining hydraulic support and mixed with the calcium chloride ball-shaped drying agent, and then the mixture is rapidly injected into the soil engineering filling device. The gangue slurry can be safely and economically absorbed by using the rear caving space of the coal mining frame; the filling device limits displacement of the gangue slurry, helps the gangue slurry to be stacked and formed and increases the height, then the drainage speed of the bottom gangue slurry is increased, the distance between a gangue slurry drainage consolidation body and a top plate is shortened, the impact load of the top plate is reduced, the drainage capacity is high, and the drainage consolidation speed of the gangue slurry is greatly increased.

Description

Technical Field

[0001] The invention belongs to the field of green coal mining and solid waste disposal technology, and in particular relates to a method for grouting waste rock drainage in the lower space of a suspended roof behind a coal mine frame. Background Art

[0002] Coal mining produces a large amount of gangue, and the environmental problems caused by gangue accumulation are becoming increasingly prominent. The country is now vigorously promoting a model where gangue is not lifted from the mine, and the gangue is filled and disposed of in situ, which can reduce the ineffective transportation of gangue, replace production capacity, improve the benefits of the mine, and alleviate environmental pressure.

[0003] The application prospect of gangue grouting filling technology in underground coal mines is good, but the bottleneck and difficulty restricting the development of this technology lies in the lack of a stable and efficient system implementation plan to achieve gangue removal without lifting. Most existing technologies take the space of collapse and dynamic development behind the frame as the only option, and the amount of gangue disposal in the space behind the frame collapse is unknown. At the same time, there is a lack of process research and verification to achieve the disposal of gangue in the space behind the frame collapse.

[0004] Based on this, the idea of ​​injecting gangue slurry into large underground spaces in coal mines (the two sides of the drift and the suspended roof space behind the fully-mechanized hydraulic support) is proposed. The consumption volume of this type of space is relatively fixed and has huge consumption potential. The existing gangue slurry, without any admixture, flows everywhere, spreads over a long distance, and is difficult to accumulate at a high level. For the suspended roof space behind the frame that may collapse at any time, the risk factor is high. In addition, the gangue slurry still has a certain fluidity within a day and is in a slurry state. If the roof collapses and impacts the gangue slurry, the gangue slurry itself cannot absorb the huge kinetic energy of the overburden collapse. After being squeezed, it is easy to be pushed into the fully-mechanized hydraulic support, causing a production safety accident.

[0005] How to prevent large-scale displacement of the gangue slurry under the overburden load that may collapse at any time, so as to avoid affecting the hydraulic support and the interior, has become the primary goal of coal mine production safety. This goal can be achieved by accelerating the drainage or rapid setting of the gangue slurry. The purpose of filling the gangue is to prevent the gangue from rising to the well, rather than to control surface subsidence. If a quick-setting agent is added to the gangue slurry, it is similar to backfilling mining, which is too costly and has a slow filling speed, making it difficult to implement.

[0006] Under the above background, a method for drainage and grouting of gangue in the lower space of the rear suspended roof of a coal mine is proposed, which provides a new way for the filling and disposal of coal mine gangue and alleviates the environmental crisis of large-scale industrial solid waste of gangue. Summary of the invention

[0007] In view of the above situation, in order to overcome the defects of the prior art, the present invention provides a method for draining and grouting waste rock in the lower space of the rear suspended roof of a coal mine frame, which at least partially solves the above technical problems.

[0008] The technical solution adopted by the present invention is as follows: a method for draining and grouting waste rock in the lower space of the rear suspended roof of a coal mine, comprising the following steps:

[0009] (1) After the raw coal is mined underground, it is transported to the underground screening-intelligent gangue selection-crushing-mixing-grouting comprehensive operation chamber through a transfer belt, and then the prepared gangue slurry is injected into the space formed by coal mining through an industrial filling pump;

[0010] (2) The gangue slurry is transported to the vicinity of the fully mechanized hydraulic support (near the slurry outlet), mixed with calcium chloride bead-shaped desiccant, and then quickly injected into the suspended ceiling space behind the support. After the desiccant is mixed with the gangue slurry, it is directly injected into the space behind the support. The desiccant will gradually absorb the water in the gangue slurry and play a certain role in fixing water.

[0011] (3) A large geotechnical filling device is added in the suspended ceiling space behind the frame to limit the flow of mixed gangue slurry. The mixed gangue slurry is directly injected into the filling device, which accelerates drainage and consolidation based on the effects of gangue material and desiccant.

[0012] Among them, in step 1, the gangue sorted by the intelligent gangue sorting machine is crushed by high-fine crushing equipment; the smaller the average particle size of the crushed gangue, the more conducive it is to long-distance pipeline transportation, but it is not conducive to drainage, and the larger the average particle size of the crushed gangue, the more conducive it is to drainage, but it is not conducive to long-distance pipeline transportation; because the main consumption space is the chute on both sides and the large area of ​​the lower space of the suspended roof behind the frame, the fluidity requirement of the gangue slurry is relatively low; therefore, in the ratio of gangue raw materials, based on the realization of long-distance transportation, the average particle size of the gangue is increased as much as possible, and the ratio range is as follows: the mass concentration of gangue is more than 75% (mass concentration = gangue solid mass / (total mass of gangue + water)), wherein the content of powder less than 0.075mm in the gangue grading is less than 5%, and the maximum particle size of the gangue grading should not be greater than 5mm; this ratio is achieved by adjusting and selecting appropriate crushing and screening equipment.

[0013] Among them, in step 2, the gangue slurry and the calcium chloride bead desiccant are mixed by a pipeline solid-liquid mixer. The volume of this mixer is generally small, consistent with the diameter of the gangue grouting pipeline. The calcium chloride bead desiccant is conveyed to the corner of the chute and the hydraulic support by a screw conveyor or pneumatic conveyor. Since the calcium chloride bead dryer has a small dosage and the beaded particles can be conveyed through a pipeline, the conveying equipment and the quantitative feeder used are both small in volume, which can meet the production needs without occupying the space in the chute. The mixer and the upper quantitative feeder need to be fixed on a movable platform to facilitate the synchronous movement with the comprehensive mining hydraulic support. This technology can be easily achieved through a mobile and retractable conveyor.

[0014] Furthermore, in step 3, the filling device includes a filling bag and a plastic drain board, the plastic drain board is laid on the bottom plate of the tunnel, and the plastic drain board is provided with a plurality of groups, and the plurality of groups of plastic drain boards are connected in sections, thereby enhancing the drainage capacity of the mixed gangue slurry at the bottom, and the water in the mixed gangue slurry flows into the plastic drain board through the filling bag, the filling bag is arranged on the plastic drain board, and a drainage pipe is pre-buried in the plastic drain board, and the plastic drain board and the pre-buried drainage pipe are both connected in sections to adapt to the working condition of the continuous movement of the comprehensive mining hydraulic support, in order to avoid the water discharged from the gangue slurry from accumulating near the comprehensive mining hydraulic support, through Through the embedded drainage pipe, it is ensured that the water discharged from the plastic drainage pipe near the comprehensive mining hydraulic support surface and the plastic drainage board at the bottom flows smoothly to the collapsed goaf behind the frame, and then flows to the drainage tunnel at the bottom of the working face. A plurality of groups of plastic drainage pipes for drainage are laid inside the filling bag; a layer of plastic drainage board laid at the bottom of the filling bag cooperates with the plastic drainage pipe laid inside the filling bag, and the mixed gangue slurry is directly injected into the filling bag. On the basis of the action of gangue material and desiccant, the drainage consolidation is accelerated, and the plastic drainage board, embedded drainage pipe, plastic drainage pipe and filling bag are installed, spliced ​​or stretched with the continuous movement of the hydraulic support.

[0015] Furthermore, a fixed structure is provided at the corners and the middle of the long side of the filling bag, and a support rod is installed in the fixed structure of the filling bag. The fixed structure can be a hook, a binding or other structure. As the comprehensive mining hydraulic support moves, three small holes for installing the filling bag support rod are drilled side by side according to the designed position of the filling bag to support the filling bag. After drilling, the filling bag support rod and the filling bag are connected, and the filling bag support rod is inserted into the drilled hole to temporarily fix the filling bag.

[0016] The filling bag adopts nylon screen with 50-200 mesh, which is light and thin, low in cost, high in strength, and has good drainage effect. Since the amount of gangue filled in the filling bag after the frame is large, the volume of the filling bag also needs to be large, and the internal space of the comprehensive mining hydraulic support is relatively small. At this time, the filling bag made of high-strength nylon screen with light texture has a very small volume after folding, which is a necessary prerequisite for realizing the construction after the comprehensive mining hydraulic support and large-volume filling. The volume of the filling bag can reach 2000m 3 The above, after the gangue slurry is injected into the filling bag made of high-strength nylon screen material, it plays the role of discharging water but not materials, thereby realizing drainage consolidation.

[0017] Furthermore, the filling bag is provided with an open hole structure matching the plastic drain pipe, and the open hole structure can be fixed to the plastic drain pipe by hooking, bundling, snapping, etc.

[0018] Among them, the filling bag is provided with a grouting interface in the direction close to the comprehensive mining hydraulic support, and is subsequently connected to the rubber grouting pipe during construction.

[0019] Among them, the outside of the plastic drainage pipe is wrapped with geotextile filter cloth, and the mixed gangue slurry inside gradually penetrates into the plastic drainage pipe. The geotextile filter cloth prevents the gangue particles from clogging the pores of the plastic drainage pipe. According to the indoor research results, the layout spacing and size of the plastic drainage pipe are designed.

[0020] After adopting the above structure, the beneficial effects of the present invention are as follows:

[0021] (1) It realizes the safe and economical use of the collapsed space behind the coal mining frame to absorb the gangue slurry.

[0022] (2) The filling bag limits the displacement of the gangue slurry, helps it to accumulate and form, increases its height, and thus accelerates the drainage speed of the gangue slurry at the bottom, shortens the distance between the gangue slurry drainage consolidation body and the top plate, and reduces the impact load on the top plate.

[0023] (3) The support rods for the filling bags are easy to construct, which solves the problem of being unable to anchor the construction on the top of the frame, and also avoids the problem of the mixed gangue slurry pressing on the filling bags, making it difficult for the filling bags to exert their filling capacity.

[0024] (4) Plastic drain boards, embedded drain pipes, plastic collection pipes, drain pipes and filling bags are installed, spliced ​​or stretched with the continuous movement of the hydraulic support to achieve synchronous movement.

[0025] (5) Plastic drainage boards and U-shaped drainage pipes are added to the bottom to avoid the accumulation of water discharged from the side of the hydraulic support near the comprehensive mining.

[0026] (6) The plastic collection and drainage pipes added at a certain designed interval inside the filling bag can give full play to its drainage capacity and greatly increase the drainage and consolidation speed of the gangue slurry. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0028] Figure 1 It is a cross-sectional schematic diagram of a method for draining and grouting waste rock in the lower space of the rear suspended roof of a coal mine proposed by the present invention;

[0029] Figure 2 It is a schematic diagram of the width direction of the fully mechanized mining working face of a method for draining and grouting waste rock in the lower space of the rear suspended roof of a coal mine proposed by the present invention;

[0030] Figure 3 for Figure 2 A partial enlarged view of

[0031] Figure 4 This is a schematic structural diagram of the filling device proposed in the present invention.

[0032] In the attached drawings: 1. filling bag, 2. plastic drain board, 3. drain pipe, 4. plastic drain pipe, 5. grouting interface, 6. support rod. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0034] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0035] like Figure 1-Figure 4 As shown, a method for draining and grouting waste rock in the lower space of the rear suspended roof of a coal mine frame comprises the following steps:

[0036] (1) After the raw coal is mined underground, it is transported to the underground screening-intelligent gangue selection-crushing-mixing-grouting comprehensive operation chamber through a transfer belt, and then the prepared gangue slurry is injected into the space formed by coal mining through an industrial filling pump;

[0037] (2) The gangue slurry is transported to the vicinity of the fully mechanized hydraulic support (near the slurry outlet), mixed with calcium chloride bead-shaped desiccant, and then quickly injected into the suspended ceiling space behind the support. After the desiccant is mixed with the gangue slurry, it is directly injected into the space behind the support. The desiccant will gradually absorb the water in the gangue slurry and play a certain role in fixing water.

[0038] (3) The gangue slurry after mixing with the desiccant still has a certain fluidity and cannot be quickly accumulated in the suspended ceiling space behind the frame, causing the filled gangue slurry to flow to the vicinity of the hydraulic support, thereby affecting normal production. Therefore, a large geotechnical filling device is added in the suspended ceiling space behind the frame to limit the flow of the mixed gangue slurry. The mixed gangue slurry is directly injected into the filling device, which accelerates drainage and consolidation based on the effects of the gangue material and desiccant.

[0039] Among them, in step 1, the gangue sorted by the intelligent gangue sorting machine is crushed by high-fine crushing equipment; the smaller the average particle size of the crushed gangue, the more conducive it is to long-distance pipeline transportation, but it is not conducive to drainage, and the larger the average particle size of the crushed gangue, the more conducive it is to drainage, but it is not conducive to long-distance pipeline transportation; because the main consumption space is the chute on both sides and the large area of ​​the lower space of the suspended roof behind the frame, the fluidity requirement of the gangue slurry is relatively low; therefore, in the ratio of gangue raw materials, based on the realization of long-distance transportation, the average particle size of the gangue is increased as much as possible, and the ratio range is as follows: the mass concentration of gangue is more than 75% (mass concentration = gangue solid mass / (total mass of gangue + water)), wherein the content of powder less than 0.075mm in the gangue grading is less than 5%, and the maximum particle size of the gangue grading should not be greater than 5mm; this ratio is achieved by adjusting and selecting appropriate crushing and screening equipment.

[0040] Among them, in step 2, the gangue slurry and the calcium chloride bead desiccant are mixed by a pipeline solid-liquid mixer. The volume of this mixer is generally small, consistent with the diameter of the gangue grouting pipeline. The calcium chloride bead desiccant is conveyed to the corner of the chute and the hydraulic support by a screw conveyor or pneumatic conveyor. Since the calcium chloride bead dryer has a small dosage and the beaded particles can be conveyed through a pipeline, the conveying equipment and the quantitative feeder used are both small in volume, which can meet the production needs without occupying the space in the chute. The mixer and the upper quantitative feeder need to be fixed on a movable platform to facilitate the synchronous movement with the comprehensive mining hydraulic support. This technology can be easily achieved through a mobile and retractable conveyor.

[0041] Wherein, in step 3, the filling device includes a filling bag 1 and a plastic drain board 2, the plastic drain board 2 is laid on the bottom plate of the tunnel, and the plastic drain board 2 is provided with a plurality of groups, and the plurality of groups of plastic drain boards 2 are connected in sections, which enhances the drainage capacity of the mixed gangue slurry at the bottom, and the water in the mixed gangue slurry flows into the plastic drain board 2 through the filling bag 1, and the filling bag 1 is arranged on the plastic drain board 2, and a drainage pipe 3 is pre-buried in the plastic drain board 2, and the plastic drain board 2 and the pre-buried drainage pipe 3 are both connected in sections to adapt to the working condition of the continuous movement of the comprehensive mining hydraulic support, in order to avoid the water discharged from the gangue slurry accumulating near the comprehensive mining hydraulic support, through The drainage pipe 3 is embedded in advance to ensure that the water discharged from the plastic drainage pipe 4 near the comprehensive mining hydraulic support surface and the plastic drainage board 2 at the bottom flows smoothly to the collapsed goaf behind the support, and then flows to the drainage tunnel at the bottom of the working face. A plurality of groups of plastic drainage pipes 4 for drainage are laid inside the filling bag 1; a layer of plastic drainage board 2 is laid at the bottom of the filling bag 1, and the plastic drainage pipe 4 is laid inside the filling bag 1. The mixed gangue slurry is directly injected into the filling bag 1. On the basis of the action of gangue material and desiccant, the drainage consolidation is accelerated. The plastic drainage board 2, embedded drainage pipe 3, plastic drainage pipe 4 and filling bag 1 are installed, spliced ​​or stretched with the continuous movement of the hydraulic support.

[0042] The filling bag 1 is provided with a fixed structure at the corners and the middle of the long side, and a support rod 6 is installed in the fixed structure of the filling bag 1. The fixed structure can be a hook, a binding or other structure. As the comprehensive mining hydraulic support moves, three small holes for installing the support rod 6 of the filling bag 1 are drilled side by side according to the designed position of the filling bag 1 to support the filling bag 1. After drilling, the support rod 6 of the filling bag 1 is connected to the filling bag 1, and the support rod 6 of the filling bag 1 is inserted into the drilled hole to temporarily fix the filling bag 1.

[0043] The filling bag 1 adopts a nylon screen with a mesh size of 50 to 200, which is light and thin, has low cost, high strength, and good drainage effect. Since the amount of gangue filled in the filling bag 1 after the frame is large, the volume of the filling bag 1 also needs to be large, and the internal space of the comprehensive mining hydraulic support is relatively small. At this time, the filling bag 1 made of a light and thin high-strength nylon screen has a very small volume after folding, which is a necessary prerequisite for realizing the post-frame construction and large-volume filling of the comprehensive mining hydraulic support. The volume of the filling bag 1 can reach more than 2000m3, and after the gangue slurry is injected into the filling bag 1 made of high-strength nylon screen material, it plays the role of water discharge but not material discharge, thereby realizing drainage and consolidation.

[0044] The filling bag 1 is provided with an open hole structure matching the plastic drain pipe 4 , and the open hole structure can be fixed to the plastic drain pipe 4 , and the fixation can be achieved by hooking, bundling, snapping, etc.

[0045] The filling bag 1 is provided with a grouting interface 5 in the direction close to the comprehensive mining hydraulic support, and is subsequently connected to a rubber grouting pipe during construction.

[0046] The outside of the plastic drainage pipe 4 is wrapped with a geotextile filter cloth, and the mixed gangue slurry inside gradually penetrates into the plastic drainage pipe 4. The geotextile filter cloth prevents the gangue particles from clogging the pores of the plastic drainage pipe 4. The arrangement spacing and size of the plastic drainage pipe 4 are designed based on the indoor research results.

[0047] The specific implementation is as follows:

[0048] During coal mining, the fully mechanized hydraulic support continues to move forward, and the mixed gangue slurry is still fluid. The space below the suspended roof behind the support is large, and the gangue slurry flows freely and cannot accumulate. If it is not limited, it will flow to the fully mechanized working face, affecting normal production. At the same time, the drainage conditions are poor in this state, and the water in the gangue slurry is difficult to discharge quickly. In addition, since the gangue slurry cannot be well accumulated, the slurry accumulation height is low and far away from the roof, the impact of the roof load is large. Based on this, it is proposed to use a filling bag 1 to limit the mixed gangue slurry, while increasing the drainage speed, increasing the height of the gangue slurry drainage consolidation body, and indirectly reducing the impact load on the roof, thereby achieving safe utilization of the space.

[0049] Install the fill bag:

[0050] Although the suspended roof space behind the coal mining rack has certain periodic collapse characteristics, there is still a risk of collapse, and workers are prohibited from entering, especially when encountering coal seams with large mining heights. Drilling holes and anchoring on the suspended roof behind the rack is too dangerous and not suitable; the mass of the filling bag 1 and the plastic drainage pipe 4 are both small, and the requirements for the support rod 6 of the filling bag 1 are low. The filling bag 1 does not need to be tightened, and is only set up to prevent the gangue slurry from covering the folded filling bag 1 during the grouting process, thereby causing the volume of the filling bag 1 to be unable to be fully utilized. As the fully-mechanized mining hydraulic support moves, according to the designed position of the filling bag 1, 3 small holes for installing the support rod 6 of the filling bag 1 are drilled side by side to support the filling bag 1. After drilling, the support rod 6 of the filling bag 1 is connected to the filling bag 1, and the support rod 6 of the filling bag 1 is inserted into the drilled hole to temporarily fix the filling bag 1.

[0051] The filling bag 1 is laid above the plastic drainage board 2 and the embedded drainage pipe 3, and the plastic drainage pipe 4 is simultaneously installed in the preset plastic drainage pipe 4 hole of the filling bag 1. The plastic drainage pipe 4 is also connected in sections to adapt to the working conditions of continuous movement of the comprehensive mining hydraulic support.

[0052] The filling bag 1 itself is made of nylon mesh material and has good telescopic and folding capabilities. During the continuous movement of the comprehensive mining hydraulic support, the filling bag 1 can be stretched synchronously with it.

[0053] The plastic drainage board 2, the embedded drainage pipe 3, the plastic drainage pipe 4 and the filling bag 1 are all installed, spliced ​​or stretched as the hydraulic support continues to move.

[0054] When the comprehensive mining hydraulic support is pushed to the designed fixed position of the filling bag 1, three small holes adapted to the support rod 6 of the filling bag 1 are drilled side by side again to connect the support rod 6 of the filling bag 1 and the filling bag 1. At the same time, the grouting interface 5 of the filling bag 1 is connected to the grouting hose.

[0055] Gangue grouting:

[0056] The internal operating space of the comprehensive mining hydraulic support is small, and there are no conditions for mixing the gangue slurry and the calcium chloride bead desiccant. A pipeline solid-liquid mixer is used. The volume of this mixer is generally small, which is consistent with the diameter of the gangue grouting pipeline; the calcium chloride bead desiccant is transported to the corner of the chute and the hydraulic support by a screw conveyor or pneumatic conveyor. Since the calcium chloride bead dryer has a small dosage and the bead-shaped particles can be transported through pipelines, the conveying equipment and quantitative feeder used are both small in size, which can meet production needs without occupying space in the chute. The mixer and the upper quantitative feeder need to be fixed on a movable platform to facilitate synchronous movement with the comprehensive mining hydraulic support. This technology can be easily achieved through mobile and retractable conveyors.

[0057] When the fully-mechanized hydraulic support and the filling bag 1 reach the designed safe distance, the mixed gangue slurry filling is carried out, and the optimal graded gangue is pumped to the vicinity of the fully-mechanized hydraulic support by an industrial filling pump, and the calcium chloride bead desiccant can be pneumatically and spirally transported to the vicinity of the fully-mechanized hydraulic support, where it is mixed by a solid-liquid mixer; after mixing, it is injected into the filling bag 1 through the grouting hose and the grouting structure of the filling bag 1.

[0058] Relying only on the limiting method, when the liquid level of the mixed gangue slurry is low, the tension force on the filling bag 1 is small and it can still be supported; but when further grouting is performed, as the liquid level of the mixed gangue slurry increases, the gravity and tension of the gangue slurry on the filling bag 1 become greater and greater, and it is easy to rupture, causing the mixed gangue slurry to overflow and even flow to the coal mining face. At this time, the mixed desiccant gradually absorbs water in the filling bag 1, causing the gangue slurry to quickly lose fluidity, thereby reducing the tension on the filling bag 1 caused by the increase in the accumulation height of the mixed gangue slurry, ensuring that it is not damaged.

[0059] The water absorbent and the gangue slurry are mixed for a short time and still have a certain fluidity. The mixed gangue slurry flows in the filling bag 1, stops when it flows to the boundary of the filling bag 1, and gradually accumulates upwards; during the accumulation process, the water absorbent gradually absorbs the water in the gangue slurry, and at the same time, the excess water is gradually discharged through the bottom drainage board and the pre-buried drainage board pipe in the middle. As the accumulation height increases, the deformation increases the load, which can accelerate the discharge of water in the gangue slurry. In addition, as the accumulation height increases, the distance between the gangue slurry drainage consolidation body and the uncollapsed top plate is reduced, reducing the impact force of the top plate.

[0060] The water discharged from the direction near the goaf flows directly to the goaf, passes through the goaf and is discharged into the drainage tunnel at the bottom of the working face. The water discharged from the direction near the comprehensive mining hydraulic support flows to the goaf through the preset drainage pipe 3 under the filling bag 1 and then continues to flow to the drainage tunnel.

[0061] In summary, by optimizing the grading of raw materials, adding desiccant and enhancing the drainage capacity of mixed gangue slurry, the rapid drainage and consolidation of gangue slurry was comprehensively achieved, thereby realizing the low-cost and safe utilization of the suspended roof space behind the coal mining frame.

[0062] Although the embodiments of the present invention have been shown and described, it is understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents. In short, if those skilled in the art are inspired by them and design structural modes and embodiments similar to the technical solution without creativity without departing from the purpose of the present invention, they shall all fall within the scope of protection of the present invention.

Claims

1. A method for draining and grouting waste rock in the lower space of the rear suspended roof of a coal mine, comprising the following steps: (1) After the raw coal is mined underground, it is transported to the underground screening-intelligent gangue selection-crushing-mixing-grouting comprehensive operation chamber through a transfer belt, and then the prepared gangue slurry is injected into the space formed by coal mining through an industrial filling pump; (2) The gangue slurry is transported to the vicinity of the fully mechanized hydraulic support and mixed with calcium chloride bead-shaped desiccant; (3) A geotechnical filling device is added in the suspended ceiling space behind the frame to limit the flow of the mixed gangue slurry, and the mixed gangue slurry is directly injected into the filling device.

2. The method for draining and grouting waste rock in the lower space of the rear suspended roof of a coal mine according to claim 1, characterized in that: In step 1, the gangue sorted by the intelligent gangue sorting machine is crushed by high-fine crushing equipment, and the ratio range of the gangue raw materials is as follows: the gangue mass concentration is above 75% (mass concentration = gangue solid mass / (total mass of gangue + water)), wherein the content of powder less than 0.075mm in the gangue grading is less than 5%, and the maximum particle size of the gangue grading should not be greater than 5mm.

3. The method for draining and grouting waste rock in the lower space of the rear suspended roof of a coal mine according to claim 2, characterized in that: In step 2, the gangue slurry and the calcium chloride bead-shaped desiccant are mixed using a pipeline solid-liquid mixer.

4. The method for draining and grouting waste rock in the lower space of the rear suspended roof of a coal mine according to claim 3, characterized in that: In step 3, the filling device includes a filling bag and a plastic drain board. The plastic drain board is laid on the bottom plate of the tunnel. The plastic drain board is provided with multiple groups, and the multiple groups of plastic drain boards are connected in sections. The filling bag is arranged on the plastic drain board. A drainage pipe is embedded in the plastic drain board. The plastic drain board and the embedded drainage pipe are connected in sections to adapt to the working condition of continuous movement of the comprehensive mining hydraulic support. Multiple groups of plastic drainage pipes for drainage are laid inside the filling bag.

5. The method for draining and grouting waste rock in the lower space of the rear suspended roof of a coal mine according to claim 4, characterized in that: The filling bag is provided with a fixing structure at the corners and the middle of the long side, and a supporting rod is installed in the fixing structure of the filling bag.

6. The method for draining and grouting waste rock in the lower space of the rear suspended roof of a coal mine according to claim 4, characterized in that: The filling bag adopts a nylon screen with a mesh size of 50 to 200.

7. The method for draining and grouting waste rock in the lower space of the rear suspended roof of a coal mine according to claim 4, characterized in that: The filling bag is provided with an opening structure matching the plastic drainage pipe.

8. The method for draining and grouting waste rock in the lower space of the rear suspended roof of a coal mine according to claim 4, characterized in that: The filling bag is provided with a grouting interface in the direction close to the comprehensive mining hydraulic support, and is subsequently connected to the rubber grouting pipe during construction.

9. The method for draining and grouting waste rock in the lower space of the rear suspended roof of a coal mine according to claim 4, characterized in that: The outer side of the plastic drainage pipe is wrapped with a geotextile filter cloth.

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