Backfilling mining method for steeply inclined coal seam ascending units

Abstract

This invention discloses a method for backfilling and mining steeply inclined coal seams in upward units. The method includes: arranging intake and return airways along the dip of the coal seam, dividing the coal seam into multiple mining stages; connecting a stage-level centralized haulage roadway at the lower construction level of each stage to the main hoisting shaft via a stage haulage gate; dividing the coal body within each stage into multiple near-horizontal mining units, and starting coal cutting operations from the lowest unit; transporting the mined coal through conveying equipment within the unit, a closed inclined chute in the intake airway, the stage-level centralized haulage roadway, and the conveying system within the stage haulage gate; after the unit mining is completed, only 70%-90% of its goaf cross-section is backfilled, reserving a ventilation section; after the backfill solidifies, the upper units are mined sequentially from bottom to top using this as a base, and utilizing the reserved ventilation section to form a full-pressure ventilation system penetrating the working face. This invention achieves safe, efficient, and high-recovery-rate mechanized mining of steeply inclined coal seams.

Description

Technical Field

[0001] This invention relates to the field of coal mining technology, and in particular to a method for backfilling mining of steeply inclined coal seams in ascending units. Background Technology

[0002] Steeply inclined coal seams (usually referring to coal seams with a dip angle greater than 45°) present numerous technical challenges during mining due to their unique geological conditions. The steep, even near-vertical, nature of the coal seam makes conventional mechanized longwall mining techniques, suitable for gently inclined coal seams, extremely unsuitable for these conditions. This results in significant problems such as difficulties in preventing equipment collapse and slippage, complex roof management, and high safety risks for personnel and equipment. Consequently, mining efficiency is low, and the risk of safety accidents is far higher than in ordinary coal seams.

[0003] Among related technologies, there are two main traditional processes for mining steeply inclined coal seams. The first is the flexible shield support mining process for steeply inclined coal seams. This method is essentially a semi-mechanized blasting coal extraction process, which uses a flexible metal support system to isolate the working face from the surrounding rock. However, this process has revealed serious defects in practical applications: the supports are at risk of being crushed (crushed by falling gangue and unable to move down) and jammed, which are difficult to handle and can easily lead to working face shutdowns; it has stringent requirements for coal seam thickness (usually 8-20 meters) and stability, and poor adaptability to changes in geological conditions; the coal recovery rate is limited (usually only 75%-85%), and the working space is narrow, the slope is steep, personnel movement and operation are difficult, and there are high safety risks such as flying gangue and gas accumulation.

[0004] The second method is the horizontal segmented top coal caving process for steeply inclined extra-thick coal seams. This method divides the extra-thick coal seam (usually thicker than 20 meters) into multiple horizontal segments along the vertical direction for mining. However, its disadvantages are also significant: the process has a narrow scope of application, only applicable to extra-thick coal seams; the coal recovery rate is low and unstable (often below 70% in practice), forming a large amount of unrecoverable triangular coal at the segment boundaries; roof gangue is easily mixed in during coal caving, resulting in a high gangue content in the coal (up to 15%-30%), making coal quality difficult to control; continuous mining in multiple segments causes stress superposition, resulting in severe mine pressure and extremely difficult support; at the same time, the roadway system is complex, ventilation and gas control are difficult, and the risk of spontaneous combustion is high. Summary of the Invention

[0005] The present invention aims to at least partially solve one of the technical problems in the related art.

[0006] Therefore, embodiments of the present invention propose a method for backfilling mining of steeply inclined coal seams in ascending units, which can safely, efficiently, and with high recovery rates mine steeply inclined coal seams.

[0007] The method for backfilling and mining steeply inclined coal seam ascending units according to embodiments of the present invention includes:

[0008] S1, an intake airway and a return airway are arranged at intervals along the dip of the coal seam. The coal seam is divided into multiple mining stages. At the lower part of each mining stage, a stage centralized transport roadway is constructed along the strike of the coal seam at a horizontal level. The stage centralized transport roadway is connected to the main hoisting shaft through a horizontal stage transport gate. S2, during the mining stage, the coal body is divided into multiple continuous mining units above the reserved roof protection layer in the centralized transport roadway of the stage. Each mining unit is arranged nearly horizontally, and mining equipment is used to advance from the air intake side to the air return side of the first mining unit at the bottom of each mining stage to carry out coal cutting operations. S3, the coal mined by the first mining unit is transferred to the closed inclined chute set in the intake airway through the first conveying equipment therein. The coal is then discharged by its own weight through the closed inclined chute to the second conveying equipment in the stage centralized transportation roadway, and then transported to the main hoisting shaft through the third conveying equipment in the stage transportation gate. S4. After the first mining unit is completed, filling material is injected into its goaf for filling, and only 70%-90% of the cross section of the goaf is filled, leaving unfilled ventilation sections. S5. After the filling material in the first mining unit solidifies to form a stable bottom plate, the mining unit immediately above it is mined in a bottom-up order based on the bottom plate of the filling body, and the steps of coal cutting, coal transportation and subsequent filling and reserved ventilation section are repeated. S6. Starting from the second mining unit, the ventilation section reserved in the mining unit below it is used to allow fresh air to enter from the intake roadway, flow through the mining unit in operation and the ventilation section, and finally be discharged from the return roadway, so as to form a full-pressure ventilation system in the mining unit.

[0009] In some embodiments, the closed inclined chute is a segmented fiberglass pipe, with each pipe section being detachably connected. The fiberglass pipe is laid along the inclined bottom plate of the intake roadway. The inlet end of the fiberglass pipe is connected to the first conveying equipment in the mining unit, and the outlet end of the fiberglass pipe is connected to the second conveying equipment in the stage centralized transportation roadway.

[0010] In some embodiments, the mining equipment is a continuous miner, a tunneling machine, or a roadheader. During the coal cutting operation, the mining equipment retreats 3-5 meters in the backward direction to provide temporary support for the roof of the mining unit. The temporary support is made of glass fiber reinforced plastic anchor bolts. The glass fiber reinforced plastic anchor bolts have tensile strength higher than a preset threshold and shear strength lower than a preset threshold, so that they can provide anchoring support and can be directly cut by the mining equipment of the mining unit above.

[0011] In some embodiments, an air volume regulating device is provided in the stage centralized transport roadway. The airflow path of the full-pressure ventilation system includes a first branch and a second branch connected in parallel. The first branch includes an intake airway, a stage centralized transport roadway, and a return airway connected in sequence. The second branch includes an intake airway, a mining unit under mining, a ventilation section reserved in the filled unit below it, and a return airway. The air volume entering the first branch and the second branch is dynamically distributed by adjusting the air volume regulating device.

[0012] In some embodiments, the filling step includes: first, crushing gangue into granules on the ground, then mixing it with water, cement and additives to form a paste, and then sending it into the coal mine through pipelines to directly fill the goaf.

[0013] In some embodiments, the filling step includes: firstly, solid filling of the goaf with gangue particles generated during underground rock tunnel excavation, and then spraying or pumping cement-based slurry onto the surface of the filled gangue layer to form a covering layer and allowing it to penetrate into the gangue gaps for consolidation.

[0014] In some embodiments, during the filling step, the filling material is transported by gravity through a filling pipeline laid underground.

[0015] In some embodiments, the coal seam is further divided into multiple parallel mining stages along the horizontal direction. Mining operations are carried out on the mining units of the parallel mining stages, while filling operations are carried out on another mining unit that has been mined and is located in a different stage or a different position in the same stage.

[0016] The steeply inclined coal seam uphill unit backfilling mining method of this invention divides the steeply inclined coal seam into multiple mining stages and divides the stages into near-horizontal mining units, transforming the complex and steep mining environment into a series of near-horizontal, standardized operation units, thereby overcoming the problem of equipment anti-tipping and anti-slipping and ensuring the safety of personnel operation.

[0017] By adopting an upward mining sequence from bottom to top and combining it with 70%-90% cross-sectional backfilling of the goaf after mining to reserve ventilation channels, a stable bottom plate with solidified backfill body as the upper mining layer is achieved. At the same time, a continuous ventilation channel is constructed to effectively control the stress of the surrounding rock, achieve full-pressure ventilation, and meet the mandatory requirements of safety regulations.

[0018] By setting up a phased centralized transport roadway and adopting a coal transport path consisting of conveying equipment within the mining unit, inclined roadway closed chutes, phased centralized transport roadways, and main hoisting shaft, efficient, closed, and gravity-assisted coal transport from the near-horizontal working face to the surface is achieved, which improves transport efficiency and eliminates the risk of coal rolling and injuring people. Attached Figure Description

[0019] Figure 1 This is a first schematic diagram of single-row coal seam mining according to an embodiment of the present invention.

[0020] Figure 2 yes Figure 1 A partial cross-sectional schematic diagram of AA.

[0021] Figure 3 This is a second schematic diagram of single-row coal seam mining according to an embodiment of the present invention.

[0022] Figure 4 This is a schematic diagram of parallel coal seam mining according to an embodiment of the present invention.

[0023] Figure 5 This is a schematic diagram of the filling cross-section according to an embodiment of the present invention.

[0024] Figure label: 1-Air intake alley; 2- Huifeng Lane; 3-stage centralized transportation lane; 4-Stage transportation to Shimen; 5-Main hoisting shaft; 6-Mining unit; 60-Backfilling unit; 61-Mining equipment; 7-Airflow regulating device; 8-Backfill material; 81-Gange; 82-Backfill slurry; 9-Roof support coal seam; 10 - Coal seam roof; 11- Reserved air duct; 12-Filling pipeline; 13-Anchor bolt. Detailed Implementation

[0025] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0026] The following describes, with reference to the accompanying drawings, a method for backfilling and mining steeply inclined coal seams in an upward unit according to an embodiment of the present invention.

[0027] like Figures 1 to 5 As shown, the method for backfilling and mining steeply inclined coal seam ascending units according to an embodiment of the present invention includes: S1, Roadway System Layout. First, two main roadways are constructed parallel to each other along the dip direction of the coal seam, i.e., at a certain distance L. The two roadways serve as intake airway 1 and return airway 2, respectively. Intake airway 1 and return airway 2 constitute the basic framework for ventilation and auxiliary transportation in the entire mining area.

[0028] Subsequently, along the vertical extension direction of the coal seam, it is divided into several mining stages, M1, M2, etc., each with a reasonable vertical elevation, for example, 100-150 meters. At the lower part of each mining stage, a stage-level centralized haulage roadway 3 (D1, D2, etc.) is constructed along the strike of the coal seam, i.e., in an approximately horizontal direction. Stage-level centralized haulage roadway 3 is a horizontal roadway located at the bottom of the coal seam in this stage, used to collect and transfer the coal produced by all mining units 6 in this stage. Figure 2 As shown, the mining stage is located inside the top plate 10 of the coal seam.

[0029] The stage haulage roadway 3 is connected to the main hoisting shaft 5 via a horizontal stage haulage gate 4. Understandably, to hoist coal to the surface, a stage haulage gate, S1, S2, etc., also a horizontal roadway, is needed to connect the stage haulage roadway to the mine's main hoisting shaft system. This breaks down the complex, steeply inclined coal seam mining space into multiple independent units connected by horizontal or near-horizontal roadways, simplifying the complexity of the transportation, ventilation, and personnel systems.

[0030] S2, Division of mining units and mining of the first unit. After the roadway system layout is completed, further division is carried out within each mining stage. From the roof of the stage centralized transport roadway 3 upwards, a certain thickness of protective coal body 9 is reserved, for example, about 10 meters, and reinforced with anchor mesh to ensure the long-term stability of the key transport roadway.

[0031] Above the roof support coal seam 9, the coal seam in this stage is divided into multiple continuous mining units c1, c2, c3, etc., with basically uniform thickness, along the horizontal direction, i.e., perpendicular to the dip direction of the coal seam. The height of each mining unit 6 is determined according to the capacity of the selected mining equipment, usually 3 to 5 meters. Since the coal seam is steeply inclined and the mining units 6 are divided along the horizontal direction, the mining face of each unit is actually arranged nearly horizontally.

[0032] Mining operations begin at the bottom of the first mining unit 6 in each mining stage. Mining equipment 61, such as a continuous coal mining machine or a roadheader, is used to advance from the intake side (near the intake roadway 1) to the return air side (near the return air roadway 2) of the unit to complete coal breaking and loading operations.

[0033] This transforms operations that were originally performed at steep inclines into operations performed under near-horizontal conditions, thereby eliminating the direct risks associated with inclines, such as equipment slippage and difficulty for personnel to walk.

[0034] S3, Coal Transportation System. After coal is mined, it is transported out via the first conveying equipment, such as a retractable belt conveyor or transfer conveyor, located within the mining unit 6. The coal is then transferred to a closed inclined chute located within the intake airway 1. Since the intake airway 1 is arranged along the dip of the coal seam, its slope is consistent with the dip angle of the coal seam, typically greater than 45°. Under the action of gravity, the coal flows down at high speed through this closed chute. The chute adopts a closed structure, effectively preventing coal from splashing and injuring people during high-speed descent, and reducing dust dispersion. After the coal is chuteed to the stage centralized transportation roadway 3 of this stage, it is received by the second conveying equipment, such as a belt conveyor, within this roadway, and then transferred by the third conveying equipment within the stage transportation gate 4, finally entering the coal bunker of the main hoisting shaft 5 and being hoisted to the surface. This achieves multi-level connection of horizontal transportation within the unit, closed inclined roadway self-flowing, centralized horizontal transportation within the stage, and vertical shaft hoisting, resulting in a smooth system with low energy consumption and high safety.

[0035] S4, partial cross-section filling and ventilation cross-section reservation. After all the coal in the first mining unit 6 is mined out, forming a goaf, it is not allowed to collapse or be completely filled. Instead, filling material is immediately injected into it to form filling unit 60. The filling material can be paste, paste-like material, or gangue mixed with slurry, etc.

[0036] During backfilling, only 70%-90% of the cross-section of the goaf is filled. That is, an unfilled reserved ventilation duct 11 is left on the top or side of the backfill body 8. The reserved ventilation duct 11 is a continuous spatial channel running the entire length of the mining unit 6, enabling full-pressure ventilation. This changes the situation in traditional backfilling or caving mining where the goaf is completely sealed or blocked, requiring reliance on local ventilation fans for long-distance ventilation. It should be noted that the arrows shown in the diagram indicate the direction of airflow.

[0037] S5, Upward Sequential Mining and Cycle. After the backfill material in the first mining unit 6 solidifies and hardens, forming a stable base plate (backfill body 8) with sufficient load-bearing strength, this backfill body 8 serves as the foundation for mining operations. Subsequently, the second mining unit 6 immediately above it is mined in a bottom-up sequence. During the mining of the second unit, personnel and equipment operate on the base plate of the backfill body 8 formed by the first unit, and the working conditions remain near-horizontal. The mining process, namely coal cutting and transportation, is the same as the first unit. After the second unit is mined, it is also partially backfilled (70%-90%), and a reserved ventilation duct 11 is provided. This process is repeated, cycling through mining, partial backfilling, and then mining the previous unit, until the entire stage of mining is completed.

[0038] The strategy of combining the upward mining sequence with the replacement of the backfill body ensures that the mining of each upper unit is carried out under a stable and reliable artificial false roof, i.e., the lower backfill body. This effectively controls the activity of the overlying strata, mitigates the mining pressure, and solves the safety problem of potential instability caused by upward mining of steeply inclined coal seams.

[0039] S6, Formation of the Full-Pressure Ventilation System. Starting from the mining of the second longwall unit 6, fresh air enters from the intake airway 1. A portion of the airflow directly enters the working face of the ongoing longwall unit 6, washing the working face and carrying dust and gas. It then descends through the reserved air duct 11 between this unit and the lower filled unit 60 (the unfilled space reserved in step S4), entering the lower filled longwall unit 6 and finally converging into the return airway 2 for discharge. Using the reserved air duct 11, the intake airway 1, multiple series-connected longwall units 6 (including those under mining and those already filled), and the return airway 2 are connected to form a complete, full-pressure ventilation system that does not rely on local ventilators. This system provides stable airflow and a large effective air volume, effectively diluting and discharging gas and dust generated at the working face, meeting the ventilation safety requirements of the "Coal Mine Safety Regulations." Specifically, it fulfills the mandatory requirement for full-pressure ventilation at longwall faces, improving the safety of the working environment.

[0040] The steeply inclined coal seam uphill unit backfilling mining method of this invention divides the steeply inclined coal seam into multiple mining stages and divides the stages into near-horizontal mining units 6, transforming the complex and steep mining environment into a series of near-horizontal, standardized operation units, thereby overcoming the problem of equipment anti-tipping and anti-slipping and ensuring the safety of personnel operation.

[0041] By adopting an upward mining sequence from bottom to top and combining it with 70%-90% cross-sectional filling of the goaf after mining to reserve ventilation ducts 11, a stable bottom plate with solidified filling body 8 as the upper mining layer is achieved. At the same time, a continuous ventilation channel is constructed to effectively control the stress of the surrounding rock, achieve full-pressure ventilation, and meet the mandatory requirements of safety regulations.

[0042] By setting up a centralized transportation roadway 3 and adopting the conveying equipment in the mining unit 6, the inclined roadway closed chute, the centralized transportation roadway 3 and the main hoisting shaft 5 coal transportation path, efficient, closed, and gravity-assisted transportation of coal from the near-horizontal working face to the surface is achieved, which plays a role in improving transportation efficiency and eliminating the risk of coal rolling and injuring people.

[0043] In some embodiments, the closed inclined chute is a segmented fiberglass pipe, with each pipe section being detachably connected. The fiberglass pipe is laid along the inclined bottom plate of the intake airway 1. The inlet end of the fiberglass pipe is connected to the first conveying equipment in the mining unit 6, and the outlet end of the fiberglass pipe is connected to the second conveying equipment in the stage centralized transport airway 3.

[0044] The enclosed inclined chute is not a single, monolithic structure, but rather an assembly of multiple sections of interconnected fiberglass pipes. The pipe sections are connected in a detachable manner, using connectors such as flanges, quick couplings, or clamps to achieve both sealing and easy assembly / disassembly.

[0045] In terms of installation and layout, the fiberglass pipe is laid along the inclined bottom plate of the intake airway 1, with its laying slope consistent with the slope of the intake airway 1, i.e., the dip angle of the coal seam. At the connection point of the transportation system, the inlet end, i.e., the upper end, of the fiberglass pipe overlaps with the unloading port of the first conveying equipment, such as a transfer conveyor or the tail of a belt conveyor, located at the exit of the mining unit 6, to receive coal; its outlet end, i.e., the lower end, overlaps with the receiving point of the second conveying equipment, such as the head of a belt conveyor or the receiving hopper, arranged in the stage centralized transportation roadway 3, to smoothly transfer the coal to the next level of horizontal transportation system.

[0046] The segmented fiberglass reinforced plastic (FRP) pipeline serves as a transportation channel for coal in the inclined roadway, specifically the intake airway 1. Its working principle is primarily based on gravity-driven flow and closed-loop guidance. After coal is discharged from the first conveying equipment within the mining unit 6, it falls into the inlet end of the FRP pipeline. Because the pipeline is laid at a large angle, typically greater than 45°, the coal gains acceleration under its own gravity and slides down the inner wall of the pipeline. The smooth and wear-resistant inner wall of the pipeline effectively reduces the frictional resistance of the sliding coal, ensuring transportation efficiency.

[0047] The reliable connection between each pipe section ensures the overall sealing and continuity of the pipeline during the impact and abrasion of coal, preventing coal leakage or dust escape. After the coal is accelerated and stabilized within the pipeline, it is discharged centrally and controllably from its outlet end and falls into the second conveying equipment of stage centralized transportation roadway 3, thus realizing a safe and efficient transition of coal from the inclined roadway to the horizontal roadway transportation system.

[0048] In this embodiment, the fully enclosed structure of the pipeline completely confines the high-speed moving coal inside the pipeline, thus completely eliminating the safety threat posed by coal rolling and splashing in steep inclined roadways to equipment and personnel in the roadway, and solving a major safety hazard in the transportation of coal in steeply inclined coal seams.

[0049] This system utilizes the natural steep dip angle of the coal seam to achieve gravity-driven coal transport, eliminating the need for additional driving power, thus reducing transportation energy consumption. The system is simple and reliable. The low coefficient of friction of the fiberglass inner wall facilitates smooth and rapid coal descent, improving transportation efficiency.

[0050] The segmented, detachable design allows for flexible assembly of the pipeline according to the actual length of the tunnel, facilitating underground transport and on-site installation. When maintenance, replacement of locally worn pipe sections, or adjustment of the transport system is required, specific pipe sections can be quickly disassembled and replaced without moving or replacing the entire chute system, reducing maintenance workload and time costs.

[0051] Fiberglass reinforced plastic (FRP) materials possess excellent properties such as light weight, high strength, corrosion resistance, and wear resistance. Their lightweight nature reduces installation burden; high strength ensures the structural integrity of the pipeline under coal impact and certain formation pressures; and wear resistance extends service life, making them particularly suitable for coal transportation conditions with severe wear. Furthermore, this structure has a certain degree of adaptability to unevenness in the tunnel floor.

[0052] In some embodiments, the mining equipment 61 is a continuous miner, a tunneling machine, or a roadheader. During the coal cutting operation, the mining equipment 61 retreats 3-5 meters in the backward direction to provide temporary support for the roof of the mining unit 6. The temporary support is made of glass fiber reinforced plastic anchor rods 13. The glass fiber reinforced plastic anchor rods 13 have a tensile strength higher than a preset threshold and a shear strength lower than a preset threshold, so that they can provide anchor support and can be directly cut by the mining equipment 61 of the mining unit 6 above.

[0053] The mining equipment 61 includes continuous miners, roadheaders, or roadheader-anchors. All mining equipment 61 are mechanized mining equipment capable of continuous or semi-continuous coal breaking and loading, suitable for operation in relatively narrow roadways or mining units 6. During coal cutting operations, as the mining equipment 61 advances, timely support is required behind it for the newly exposed roof, i.e., the coal seam roof.

[0054] The support is implemented within a range of 3-5 meters behind the retreat direction of the mining equipment 61, i.e., the direction of the mined-out area. The material used for the support is anchor bolt 13 made of glass fiber reinforced plastic (GFRP). The tensile strength of anchor bolt 13 is higher than a preset threshold, for example, reaching or approaching the strength standard of steel anchor bolts of the same grade, to ensure its anchoring and suspension capabilities; at the same time, its shear strength is lower than a preset threshold, significantly lower than that of steel, giving it high tensile strength and low shear strength mechanical properties.

[0055] As the mining equipment 61 advances by cutting through the coal face, the roof coal seam within a 3-5 meter radius behind it is temporarily exposed without support. At this time, construction personnel or supporting equipment immediately install fiberglass reinforced plastic anchor bolts 13 on the roof in this area. Because these anchor bolts 13 have high tensile strength, they can effectively anchor into the stable rock strata above the roof coal seam, or form a firm bond with the surrounding coal seam through anchoring agents such as resin cartridges. This provides a suspension effect and combined beam effect to the lower, potentially delaminating or loosened roof coal seam, preventing immediate collapse and providing a safe temporary working space for personnel and equipment.

[0056] After this mining unit 6 is completed and filled, the next mining unit 6 above it will begin mining. At this time, the mining equipment 61 of the upper unit, such as the cutting drum of a continuous miner or tunneling machine, will inevitably cut into the anchor bolts 13 already installed in the roof of the lower unit during the coal breaking process. Due to the low shear strength of the glass fiber reinforced plastic anchor bolts 13, they can be cut relatively easily when subjected to the shearing action of the cutting drum of the mining equipment, without causing severe wear, impact, or even damage to the cutting tools as steel anchor bolts do. The cut anchor bolt fragments 13 can be transported out with the coal or partially recycled, ensuring that the mining operation of the upper unit can proceed smoothly without being hindered by the remaining support materials in the lower layer.

[0057] In this embodiment, by installing high-tensile-strength fiberglass anchor bolts 13 3-5 meters in a timely manner (with a delay), the stability of the roof of the mining unit 6 during the mining process was effectively controlled, preventing roof collapse accidents. High tensile strength ensures the effectiveness of the support, while low shear strength ensures its cutability, solving the problem that traditional steel anchor bolts, when used as temporary support, would cause serious obstacles to subsequent upward mining, requiring pre-removal or leading to equipment damage. The mining equipment 61 does not need to avoid or deal with robust residual steel support; the cutting process is smooth, reducing abnormal tool wear, broken teeth, and even mechanical failures caused by cutting metal, thus improving the reliability of continuous operation and overall mining efficiency. Fiberglass reinforced plastic material has a certain recycling value; some of the rods or materials that are not completely destroyed can be recycled.

[0058] In some embodiments, an air volume regulating device 7 is provided in the stage centralized transport roadway 3. The airflow path of the full-pressure ventilation system includes a first branch and a second branch connected in parallel. The first branch includes an intake airway 1, a stage centralized transport roadway 3 and a return airway 2 connected in sequence. The second branch includes an intake airway 1, a mining unit 6 under mining, a reserved air duct 11 reserved in the filled unit 60 below it and a return airway 2. The air volume entering the first branch and the second branch is dynamically distributed by adjusting the air volume regulating device 7.

[0059] An air volume regulating device 7 is installed in the centralized transport roadway 3. The air volume regulating device 7 can be a manually or automatically controlled air window, air door, or regulating damper, etc., used to change the ventilation resistance of the roadway, thereby regulating the amount of air passing through the roadway.

[0060] The first branch, also known as the auxiliary ventilation or regulating branch, allows airflow to pass sequentially through intake airway 1, stage centralized transport airway 3, and return airway 2. This path does not directly pass through the ongoing longwall face.

[0061] The second branch, namely the main ventilation or working face branch, flows sequentially through intake airway 1, the working face of the ongoing mining unit 6, the reserved ventilation duct 11 of the already filled unit 60 below it, and return airway 2. This path directly serves the working face and is the core channel for diluting gas, reducing dust, and supplying fresh air.

[0062] By operating the air volume regulating device 7, which is manually or automatically set in the stage centralized transport tunnel 3, the air volume ratio entering the first branch and the second branch can be dynamically allocated in real time. The first branch and the second branch of the stage centralized transport tunnel 3 are set to be connected in parallel.

[0063] In a ventilation network, the airflow distribution of parallel branches is naturally inversely proportional to their resistance. Airflow regulating device 7 is installed in the stage centralized transport roadway 3, i.e., the first branch. When it is necessary to increase the airflow into the working face, i.e., the second branch, the airflow regulating device 7 can be reduced or adjusted to increase the ventilation resistance of the first branch.

[0064] According to the natural distribution law of air volume in parallel airflow paths, more of the total intake air will flow to the second branch with relatively lower resistance, thereby increasing the effective air volume at the working face. Conversely, if excessive air volume at the working face may cause problems such as dust flying or if the first branch needs maintenance, the regulating device can be turned up to reduce the resistance of the first branch, allowing some airflow to short-circuit through the first branch, thereby reducing or precisely controlling the air volume at the working face.

[0065] During the mining process, parameters such as gas emission, dust generation, and temperature at the working face are dynamically changing. By monitoring these parameters, the air volume regulating device 7 can be dynamically adjusted to achieve on-demand and precise air supply to the working face, ensuring that ventilation is always in optimal condition.

[0066] In this embodiment, the traditional extensive ventilation mode, which relies on the total air pressure of the main ventilator and the natural distribution of airflow in the roadway, is changed. By adjusting the resistance of the first branch road, namely the stage centralized transport roadway 3, the airflow entering the second branch road, namely the working face, can be precisely and flexibly adjusted, ensuring that the working face receives sufficient and suitable fresh airflow at any production stage, effectively coping with fluctuations in gas and dust. Even if the cross-section of the second branch road, namely the working face passage, is slightly reduced or the resistance is temporarily increased due to factors such as minor roof spalling, the airflow will automatically be adjusted to a certain extent through the first branch road, avoiding the risk of sudden windlessness or sharp reduction in airflow at the working face, and enhancing the system's anti-interference capability. Adjusting the airflow according to the actual needs of the working face avoids the energy waste caused by excessive airflow, realizing on-demand ventilation, which is conducive to energy conservation and emission reduction.

[0067] In some embodiments, the filling step includes: first, crushing gangue 81 into granules on the ground, then mixing it with water, cement and additives to form a filling slurry 82, which is a paste, and sending it into the coal mine through the filling pipeline 12 to directly fill the goaf.

[0068] First, on the ground, the gangue 81 generated by coal mining or similar inert materials purchased from outside are crushed into granules using crushing equipment to form aggregates that meet certain gradation requirements.

[0069] The crushed gangue 81 particles are added to a mixing device along with water, cement, and necessary additives such as water-reducing agents, early-strength agents, and suspending agents in a predetermined ratio. The mixture is thoroughly mixed to prepare a high-concentration, fluid-grade filling slurry 82, i.e., a paste-like slurry. This paste is stable when still, without bleeding or settling, and can regain its fluidity under external force, such as pump pressure or gravity.

[0070] The prepared paste is sent into the coal mine through the filling pipeline 12 system, which is usually a pipeline in a borehole or a dedicated filling well, by means of pump pressure or gravity, and is directly transported to the target goaf area, that is, the unit that has been mined out, for filling.

[0071] In this embodiment, the good rheological properties of the paste in the pipeline, such as a certain yield stress and viscosity, are utilized. Pressure is provided by the surface filling pump, or the gravitational potential energy formed by the elevation difference between the surface preparation station and the downhole filling point is used to drive the paste to achieve long-distance, stable plunger flow or structured flow transportation in the pipeline, effectively avoiding pipe blockage and segregation.

[0072] After the paste is transported to the goaf, due to its good fluidity and stability, it can self-level and self-compact within the goaf, effectively filling corners and contacting the roof, thus reducing voids. The cement in the paste undergoes a hydration reaction, and the slurry gradually solidifies and hardens, eventually forming an integral filling body with certain early and late strength.

[0073] By adjusting the cement content and mix ratio, the final strength of the backfill material 8 can be precisely controlled, ensuring it meets the mechanical requirements of serving as a stable foundation for the upper mining layers, i.e., an artificial false roof. The backfill material is prepared centrally on the surface, with only pipeline transportation and injection underground. This simplifies the operation, generates almost no dust, and significantly improves the underground backfilling working environment. It also effectively utilizes a large amount of surface-stocked gangue 81, achieving resource utilization without occupying land. Simultaneously, the high roof contact rate of the paste backfill effectively controls the movement of the overlying strata, significantly reducing surface subsidence and demonstrating outstanding environmental benefits.

[0074] In other embodiments, the filling step includes: firstly, solid filling of the goaf with gangue 81 particles generated during underground rock tunnel excavation; then, sprinkling or pumping cement-based slurry onto the surface of the already filled gangue 81 layer to form a covering layer that penetrates into the gangue fissures for consolidation. Combining slurry sprinkling and gangue 81 filling utilizes both the low cost of gangue 81 filling and the strength and stability of the paste-based solidified filling, while significantly reducing costs.

[0075] First, the gangue 81 directly generated during the excavation of underground rock tunnels in coal mines is simply crushed or gangue 81 of suitable size is directly used and transported to the vicinity of the goaf using transportation equipment such as mine cars or belt conveyors. Then, these gangue 81 particles are thrown into the goaf using gangue throwing machines, belt throwing machines or manual methods to carry out preliminary solid filling and occupy the lower space of the goaf.

[0076] After the gangue 81 layer is filled and reaches a certain stacking height and density, a cement-based slurry, typically a thin slurry composed of cement, fly ash, and water, is sprayed or pumped onto the surface of the filled gangue 81 layer through pipes. This slurry forms a covering layer on the surface of the gangue 81 layer and, by gravity, seeps downwards into the gaps between the gangue 81 particles.

[0077] In this embodiment, the dumped gangue 81 particles form a loose solid skeleton within the goaf, rapidly filling the space and providing initial support to the roof. Subsequently applied cement-based slurry penetrates the pores of the gangue 81 skeleton, encapsulating the gangue 81 particles. The cement in the slurry undergoes a hydration reaction, binding the loose gangue 81 particles into a cohesive whole, thereby significantly improving the overall strength and stability of the filling body 8. After the surface slurry cover hardens, it forms a relatively flat and robust crusted layer, serving as an ideal working base for upper-level mining.

[0078] By utilizing the primary backfill aggregate, virgin gangue 81 generated during underground tunneling, the on-site and real-time processing of gangue 81 is achieved, eliminating the need for hoisting to the surface and complex surface preparation systems, thus significantly reducing backfilling costs. The gradation requirements for gangue 81 are relatively lenient, and the process is relatively simple, making it particularly suitable for mines with small backfilling volumes or limited backfilling space, as well as for use as an initial or auxiliary backfilling method.

[0079] In some embodiments, during the filling step, the delivery of filling material is accomplished by gravity flow through the filling pipeline 12 laid underground.

[0080] The transportation of filling material is accomplished through filling pipelines 12 laid underground. The filling pipeline system 12 is a dedicated pipeline network connecting filling material sources, such as the borehole opening of the surface preparation station, the underground slurry mixing station, or the gangue delivery point, to the target goaf. The flow of filling material in the pipeline is accomplished by gravity, utilizing the natural elevation difference (potential energy) between the filling material delivery point (starting point) and the goaf filling point (ending point) as the driving force, eliminating the need for additional pumping equipment such as filling pumps or slurry pumps to provide transportation pressure.

[0081] The system, through tunnel layout or borehole design, ensures that the elevation of the filling material delivery point is significantly higher than the filling inlet elevation of the target goaf, thus creating a stable and sufficiently large vertical elevation difference between the two. This elevation difference is converted into gravitational potential energy, the driving force for the flow of the filling material, whether paste or cement slurry, in the pipeline. After the filling material enters the inclined or vertical filling pipeline 12 from the delivery point, it begins to flow downwards along the pipeline under its own gravity. By installing valves, regulators, or buffer devices at the beginning of the filling pipeline 12 or along its route, the delivery speed and flow rate of the filling material are controlled, achieving precise control of the filling process and preventing excessive pipeline wear or uneven filling due to excessive flow velocity.

[0082] In some embodiments, the coal seam is further divided into multiple parallel mining stages along the horizontal direction. Mining operations are carried out on the mining unit 6 of the parallel mining stages, while filling operations are carried out on another mining unit 6 that has been mined and is located in a different stage or a different position in the same stage. This can realize parallel operation of coal mining and filling in different zones, thereby maximizing efficiency and production capacity.

[0083] Along the strike direction of the coal seam, the mining is not divided into a single stage, but rather into multiple parallel stages. These stages may be the same or different in vertical height, but they are arranged side by side in horizontal projection, sharing the same main hoisting shaft 5 and part of the main roadway system.

[0084] The production operation plan allows for the simultaneous execution of two different types of core operations in different spatial locations of the mining unit 6: normal mining operations such as coal cutting and transportation are carried out in one or more mining phases within one or more mining units 6. Simultaneously, backfilling operations are performed in another mining unit 6 that has already been mined.

[0085] The backfilling unit 60 may be located in different mining stages, for example, while mining is underway in stage M1, backfilling may be carried out in stage M2. Alternatively, it may be located at different locations within the same mining stage, for example, while mining is underway in the east wing unit of stage M1, backfilling may be carried out in the west wing unit of stage M1 after mining has been completed.

[0086] Coal mining and backfilling, two processes that are traditionally sequential and mutually restrictive, are decoupled in time and space and designed to operate independently and synchronously as parallel production lines. This parallel operation of the two main processes breaks through the bottleneck of traditional sequential operations, effectively utilizes time and space resources, and maximizes the mine's overall production capacity (tons / day), making it particularly suitable for mining areas with high output requirements.

[0087] The mining and backfilling teams and equipment can operate continuously and at full capacity, reducing equipment downtime and personnel waiting time caused by alternating processes, improving the utilization rate of human and equipment resources, and thus reducing the production cost per unit output. For a new mining stage or mining area, since backfilling follows mining, the upper unit can be ready for mining earlier, accelerating the mining cycle speed of a single stage or even the entire mining area, which is conducive to shortening the mine's production time or increasing the resource recovery speed.

[0088] In summary, this invention provides a method for backfilling and mining steeply inclined coal seams in ascending units.

[0089] In single-line operation mode, the sequence is from bottom to top and alternating between mining and filling. First, the basic construction of the shaft system is completed: parallel intake airway 1 and return airway 2 are constructed along the dip of the coal seam, dividing the coal seam into several mining stages along the vertical depth. At the bottom of each stage, a horizontal stage central transport roadway 3 is excavated and connected to the main hoisting shaft 5 through a horizontal stage transport gate 4.

[0090] Subsequently, within the stage, the coal seam is divided into multiple continuous, near-horizontal mining units 6 above the roof protection layer of the stage centralized transport roadway 3. Mining operations begin from the lowest mining unit 6, using continuous miners and other equipment to advance from the intake air side to the return air side. The mined coal is transferred via the unit's conveying equipment to the closed inclined chute (preferably segmented fiberglass pipeline) laid in the intake air roadway 1, where it slides by gravity to the conveyor in the stage centralized transport roadway 3, and then through the stage transport gate 4 to the vertical shaft for hoisting.

[0091] After the unit is mined out, filling material is immediately injected into its goaf through the filling pipeline 12. The key is to fill only 70%-90% of the cross-section of the goaf, thus reserving continuous unfilled ventilation ducts 11. After the filling body 8 solidifies to form a stable floor, the adjacent upper mining unit 6 is mined based on this, and the steps of coal cutting, transportation, and partial filling are repeated.

[0092] Starting from the second mining unit, the reserved air duct 11 in the lower unit can be used to allow fresh air to enter from the intake airway 1, flow through the working face and the reserved air duct 11, and then exit from the return airway 2, thus constructing a full-pressure ventilation system. This model has a clear logic, simple procedures, and is easy to manage, making it particularly suitable for initial production or areas with complex geological conditions.

[0093] In parallel operation mode, higher resource utilization and production capacity are achieved. Based on all the technical characteristics of single-line operation, it optimizes spatial and temporal allocation by dividing the coal seam into multiple parallel mining stages along the horizontal direction (i.e., strike direction) or by rationally planning the mining and backfilling progress of different areas within the same stage. Its core lies in separating the two key processes of coal mining and backfilling spatially while synchronizing them temporally. For example, while coal mining is being organized in a certain mining unit 6 of a mining stage such as M1, backfilling operations can be simultaneously carried out in another mining stage such as M2 or in another mined area of ​​the same stage, M1.

[0094] This is thanks to the independent unitized design, the non-interfering coal transportation and filling systems, and the independent ventilation capacity ensured by the reserved ventilation duct 11. The parallel operation mode allows the coal mining equipment and teams, as well as the filling equipment and teams, to work at near-continuous full capacity, significantly reducing the waiting time between processes and shortening the total cycle from the completion of mining to providing a stable floor for the upper layers. This significantly improves the continuous coal production capacity and overall economic benefits of the entire mine. This mode reflects the high flexibility and scalability of the system design of this invention, and is suitable for large-scale mining areas with high output requirements and stable production systems.

[0095] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0096] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0097] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0098] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0099] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0100] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for backfilling and mining steeply inclined coal seams in ascending units, characterized in that, include: S1, an intake airway and a return airway are arranged at intervals along the dip of the coal seam. The coal seam is divided into multiple mining stages. At the lower part of each mining stage, a stage centralized transport roadway is constructed along the strike of the coal seam at a horizontal level. The stage centralized transport roadway is connected to the main hoisting shaft through a horizontal stage transport gate. S2, during the mining stage, the coal body is divided into multiple continuous mining units above the reserved roof protection layer in the centralized transport roadway of the stage. Each mining unit is arranged nearly horizontally, and mining equipment is used to advance from the air intake side to the air return side of the first mining unit at the bottom of each mining stage to carry out coal cutting operations. S3, the coal mined by the first mining unit is transferred to the closed inclined chute set in the intake airway through the first conveying equipment therein. The coal is then discharged by its own weight through the closed inclined chute to the second conveying equipment in the stage centralized transportation roadway, and then transported to the main hoisting shaft through the third conveying equipment in the stage transportation gate. S4. After the first mining unit is completed, filling material is injected into its goaf for filling, and only 70%-90% of the cross section of the goaf is filled, leaving unfilled ventilation sections. S5. After the filling material in the first mining unit solidifies to form a stable bottom plate, the mining unit immediately above it is mined in a bottom-up order based on the bottom plate of the filling body, and the steps of coal cutting, coal transportation and subsequent filling and reserved ventilation section are repeated. S6. Starting from the second mining unit, the ventilation section reserved in the mining unit below it is used to allow fresh air to enter from the intake roadway, flow through the mining unit in operation and the ventilation section, and finally be discharged from the return roadway, so as to form a full-pressure ventilation system in the mining unit.

2. The method for backfilling and mining steeply inclined coal seams in ascending units according to claim 1, characterized in that, The closed inclined chute is a segmented fiberglass pipe, with each pipe section being detachably connected. The fiberglass pipe is laid along the inclined bottom plate of the intake roadway. The inlet end of the fiberglass pipe is connected to the first conveying equipment in the mining unit, and the outlet end of the fiberglass pipe is connected to the second conveying equipment in the stage centralized transportation roadway.

3. The method for backfilling and mining steeply inclined coal seams in ascending units according to claim 1 or 2, characterized in that, The mining equipment is a continuous miner, a tunneling machine, or a roadheader. During the coal cutting operation, the mining equipment retreats 3-5 meters in the backward direction to provide temporary support for the roof of the mining unit. The temporary support uses anchor bolts made of glass fiber reinforced plastic. The glass fiber reinforced plastic anchor bolts have tensile strength higher than a preset threshold and shear strength lower than a preset threshold, so that they can provide anchor support and can be directly cut by the mining equipment of the mining unit above.

4. The method for backfilling and mining steeply inclined coal seams in ascending units according to claim 1, characterized in that, The stage centralized transport roadway is equipped with an air volume regulating device. The airflow path of the full-pressure ventilation system includes a first branch and a second branch connected in parallel. The first branch includes an intake airway, a stage centralized transport roadway, and a return airway connected in sequence. The second branch includes an intake airway, a mining unit under operation, a ventilation section reserved in the filled unit below it, and a return airway. The air volume entering the first branch and the second branch is dynamically distributed by adjusting the air volume regulating device.

5. The method for backfilling and mining steeply inclined coal seams in ascending units according to claim 1, characterized in that, The filling process includes: first, crushing the gangue into granules on the ground, then mixing it with water, cement and additives to form a paste, which is then piped into the coal mine and directly filled into the goaf.

6. The method for backfilling and mining steeply inclined coal seams in ascending units according to claim 1, characterized in that, The filling steps include: first, solid filling of the goaf with gangue particles generated during underground rock tunnel excavation; then, sprinkling or pumping cement-based slurry onto the surface of the filled gangue layer to form a covering layer and allowing it to seep into the gangue gaps for consolidation.

7. The method for backfilling and mining steeply inclined coal seam ascending units according to claim 5 or 6, characterized in that, In the filling step, the filling material is transported by gravity through filling pipelines laid underground.

8. The method for backfilling and mining steeply inclined coal seams in ascending units according to claim 1, characterized in that, The coal seam is further divided into multiple parallel mining stages along the horizontal direction. Mining operations are carried out on the mining units of the parallel mining stages, while filling operations are carried out on another mining unit that has been mined and is located in a different stage or a different position in the same stage.

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