A method of grid duct ventilation suitable for use in a stope being mined by means of a downward drift

Abstract

The application provides a grid type pipeline ventilation method suitable for downward drift filling stope, which comprises the following steps: carrying out grid type pipeline ventilation scheme design of the downward drift filling stope, constructing a one-layer one-step drift stope X, Y and Z three-way pipeline ventilation system, constructing a one-layer two-step drift stope X, Y and Z three-way pipeline ventilation system, and constructing a one-layer below drift stope Y and Z way pipeline ventilation system to form an overall grid type pipeline ventilation system. The application can effectively solve the problem that the downward drift stope has no independent return air channel and is difficult to form through air flow, guarantee the safety of stope operation, save engineering quantity and reduce cost; the local ventilator does not need to be moved multiple times, and the air flow can be prevented from reversing at the same time; the grid type pipeline ventilation system can return air in multiple ways, and the air resistance is small, the air speed is high, and the efficiency is high.

Description

Technical Field

[0001] This invention relates to the field of ventilation technology for underground metal and non-metal mines, and specifically to a grid-type duct ventilation method suitable for down-entry filling stopes. Background Technology

[0002] As metallic and non-metallic minerals are increasingly being mined at greater depths, the downward-entry backfilling method is required for mining soft and fractured ore bodies at depth. Downward-entry backfilling stopes use stratified exit tunnels as entrances and exits, and the stopes are single-ended. Due to the small cross-section and long distance of the access tunnels, and the lack of independent return air ducts within the stope, only small-diameter ventilation ducts combined with local ventilators can be used for long-distance forced-in, extracted, or mixed local ventilation. This results in low air velocity and high resistance, making it difficult to quickly remove toxic and harmful gases and the heat of hydration from the backfill material generated after blasting, seriously threatening the safety of stope workers. Therefore, how to construct return air channels in downward-entry backfilling stopes to quickly remove heat and smoke has become a key focus and challenge in ventilation work for downward-entry backfilling stopes.

[0003] Chinese invention patent application CN116677444A discloses a ventilation structure and method for down-entry backfilling mining. The method involves constructing an artificial false roof after the current layer of the approach is mined out. According to the layout of the next layer of the approach, ventilation channels are reserved along the strike at the bottom of the approach stope to form the return air channel for the next layer of the approach. During the mining process of the next layer of the approach, as the mining progresses, the ventilation openings are gradually exposed to form a return air channel with through airflow in the stope, which can greatly improve the ventilation efficiency and effect of the approach stope. However, in this structure, since the reserved ventilation duct erected at the bottom of the access stope is connected to the ventilation connecting duct and return air filling well erected at the end of the stope, when the first access duct of the lower layer of the top layer is filled, the ventilation connecting duct at the end of the stope and the return air filling well at the bottom of the lower layer will also be filled. Therefore, this invention can only form a return air channel with through airflow in the stope when the first access duct of the lower layer of the top layer is mined. For other access ducts, because the ventilation connecting duct and return air filling well at the end of the stope are filled tightly, even if a reserved ventilation duct is erected at the bottom of the stope of other access ducts, a return air channel with through airflow cannot be formed. Summary of the Invention

[0004] To address the technical problems existing in the prior art, the present invention provides a grid-type duct ventilation method suitable for down-entry filling stopes, which can quickly and effectively construct a through-flow return air channel in the top two-step and the lower down-entry filling stopes.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] A grid-type duct ventilation method suitable for down-entry backfilling stopes includes the following steps:

[0007] S1. Design of a grid-type duct ventilation scheme for the downward-entry filling stope.

[0008] The down-entry filling stope is divided into 1 to N layers from top to bottom, where N≥2. The height of each layer is h=3~5m. Each layer is equipped with an ore outlet. One end of the ore outlet connects to the middle section or segment roadway, and the other end connects to the down-entry stope. Each layer of the down-entry stope is mined every other layer, and the mining is carried out in two steps.

[0009] The design uses the completed 1st layer ore outlet as the main return airway of the downward access filling stope.

[0010] The designed grid-type duct ventilation system for the mining area includes: a single-layer access ventilation duct, an internal check valve, a local ventilator at the duct opening, a transverse ventilation duct perpendicular to the side wall of the access duct and connecting all access ducts in the same layer, a longitudinal ventilation duct perpendicular to the bottom plate of the access duct and connecting all access ducts in the vertical direction, a three-dimensional tee or three-dimensional cross-junction pre-embedded in the center of each access duct in the single-layer layer, and a planar tee or planar cross-junction pre-embedded in the center of each access duct in layers below the single-layer layer;

[0011] S2. Construct a three-way duct ventilation system (X, Y, Z) for the single-layer, one-step approach mining area.

[0012] After the first-stage, one-step backfilling is completed, during the construction of the false bottom, a three-dimensional tee or four-way connector is pre-embedded in the center of the false bottom. The Z-port of the three-dimensional tee or four-way connector passes through the pre-reserved circular hole in the false bottom and faces downwards. The pipe opening is sealed with a plug. The X-port and Y-port are both higher than the upper surface of the false bottom. The X-port faces the entrance of the entrance along the direction of the entrance, and the Y-port faces the side wall of the entrance perpendicularly. The X-port connects to the ventilation pipe of the first-stage entrance and is laid to the outside of the backfilling retaining wall. A check valve is installed inside the pipe, and the pipe opening is connected to a local ventilation fan. The Y-port connects to the transverse ventilation pipe and extends vertically to the side wall of the entrance. The pipe opening is sealed with a plug.

[0013] S3. Construct a three-way duct ventilation system (X, Y, Z) for a 1-layer, two-step approach mining area.

[0014] When the strength of the backfill body of the first-step approach in the first layer meets the standard, the transverse ventilation pipe pre-embedded in the first-step approach is exposed from the side wall during the mining of the second-step approach in the first layer. The pipe plug is opened and the local ventilation fan at the pipe opening of the first-step approach ventilation pipe is turned on, so that the sewage air in the second-step mining area can return through the transverse ventilation pipe and the first-step approach ventilation pipe in the first layer. After the mining of the second-step approach in the first layer is completed, a three-dimensional tee or three-dimensional cross is pre-embedded in the false bottom in the center of the approach. The Z port of the three-dimensional tee or three-dimensional cross passes through the pre-reserved circular hole in the false bottom and faces downward vertically. The pipe opening is sealed with a plug. The X port and Y port are both higher than the upper surface of the false bottom. The Y port faces the side wall of the approach vertically. The transverse ventilation pipe is connected to the exposed transverse ventilation pipe of the first step and is tightly connected. The X port is connected to the approach ventilation pipe and laid to the outside of the backfill retaining wall. A check valve is installed in the pipe and the pipe opening is connected to the local ventilation fan.

[0015] S4. Construct a Y and Z direction duct ventilation system for the access mining area below level 1, forming an integrated grid-type duct ventilation system.

[0016] When mining the first step of the access road below the first layer, the Z-port of the three-dimensional tee or four-dimensional cross passage pre-embedded in the upper layer is exposed by the roof of the access road. The pipe plug is opened so that the sewage air in the access road can return to the ore exit road of the first layer through the longitudinal ventilation pipe and the ventilation pipe of the first layer access road. After the access road is mined out, a plane tee or plane four passage is pre-embedded in the false bottom in the center of the access road. One end of the plane tee or plane four passage has a Z-port that passes through the pre-reserved circular hole in the false bottom and faces downwards. The pipe opening is sealed with a plug. The other end of the Z-port is connected to the longitudinal ventilation pipe and is tightly connected to the Z-port exposed in the roof. The Y-port is connected to the transverse ventilation pipe and extends vertically to the side wall of the access road. The pipe opening is sealed with a plug.

[0017] When mining in two steps below level 1, the transverse ventilation pipe pre-embedded in level 1 is exposed from the side wall, and the Z-port of the three-dimensional tee or four-dimensional cross pre-embedded in level 1 is exposed from the roof. The pipe plug is opened, so that the sewage air in the mining area of ​​this approach can return through the transverse ventilation pipe, the longitudinal ventilation pipe, and the ventilation pipe of level 1 approach. After the approach is completed, a plane tee or plane cross is pre-embedded in the false bottom in the center of the approach. One end of the plane tee or plane cross passes through the pre-reserved circular hole in the false bottom and faces downward vertically. The pipe opening is sealed with a plug. One end of the Z-port is connected to the longitudinal ventilation pipe and is tightly connected to the Z-port exposed in the roof. The Y-port is connected to the transverse ventilation pipe and is tightly connected to the exposed transverse ventilation pipe of level 1.

[0018] When mining each lower-level access road, repeat steps S3 to S4 to eventually form a grid-type pipeline ventilation system for the mining area.

[0019] Compared with existing technologies, the grid-type duct ventilation method for down-entry filling stopes provided by this invention has the following advantages: 1) After the ventilation duct, local ventilator, and check valve in the top-level down-entry stope are installed, they can serve as the main return air channel for the lower-level down-entry stopes, eliminating the need for multiple relocations of the local ventilator and preventing airflow reversal. 2) For one-step or two-step down-entry mining in the layers below the top level, multiple parallel return air channels can be connected through the grid-type duct ventilation system, resulting in low wind resistance, high wind speed, and high efficiency. 3) It can effectively solve the problem of down-entry stopes lacking independent return air channels and difficulty in forming through-flow, ensuring the safety of stope operations, and reducing engineering workload and cost.

[0020] Furthermore, the net diameters of the ventilation pipes, three-dimensional tees, three-dimensional crosses, planar tees, planar crosses, and pipe plugs are the same, with a net diameter of 0.8~1.2mm.

[0021] Furthermore, the ventilation pipes, three-dimensional tees, three-dimensional crosses, planar tees, planar crosses, and pipe plugs are all made of flame-retardant PVC, PP, or PPH materials, and the pressure that the pipe wall thickness can withstand should be greater than P=ρgh, where ρ is the bulk density of the filling slurry, g is the gravitational acceleration, and h is the height of the filling body in a single inlet.

[0022] Furthermore, the check valve installed inside the 1-layer inlet ventilation duct is a butterfly check valve, and the nominal diameter of the check valve is consistent with the inner diameter of the ventilation duct.

[0023] Furthermore, the local ventilation fan installed at the inlet of the ventilation duct in the first layer of the access road is a high-efficiency, low-energy, low-noise mine local ventilation fan of the same model with a mine safety mark. The fan power is 11kW, 15kW or 22kW, and the outer diameter of the fan inlet is consistent with the inner diameter of the ventilation duct. Attached Figure Description

[0024] Figure 1 This is a schematic diagram illustrating the implementation of step S2 of the method provided by the present invention.

[0025] Figure 2 This is a schematic diagram illustrating the implementation of step S3 of the method provided by the present invention.

[0026] Figures 3-7 This is a schematic diagram illustrating the implementation of step S4 of the method provided by the present invention.

[0027] Figure 8 This is a schematic diagram illustrating the installation of a local ventilation fan and a check valve at the inlet of a ventilation duct, as established in an embodiment of the present invention.

[0028] In the diagram: 1. 1-layer ore outlet tunnel; 2. 1-layer first-step approach; 3. 1-layer second-step approach; 4. 1-layer approach ventilation pipe; 5. Horizontal ventilation pipe; 6. Longitudinal ventilation pipe; 7. Local ventilation fan; 8. 2-layer ore outlet tunnel; 9. 2-layer first-step approach; 10. 2-layer second-step approach; 11. 3-layer ore outlet tunnel; 12. 3-layer first-step approach; 13. 3-layer second-step approach; 14. 4-layer ore outlet tunnel; 15. 4-layer first-step approach; 16. 4-layer second-step approach; 17. Check valve. Detailed Implementation

[0029] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below with reference to specific illustrations.

[0030] In the description of this invention, it should be understood that the terms "longitudinal," "radial," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0031] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0032] In one implementation, the construction of a grid-type pipeline ventilation system in the down-entry filling mining area of ​​a lead-zinc mine in Yunnan Province is taken as an example.

[0033] A lead-zinc mine in Yunnan Province uses the downward-entry backfilling method. Its panel is divided into four layers from top to bottom, each 3 meters high. Each layer has an exit tunnel, one end of which connects to the access stope, and the other end connects to the section roadways. Each section roadway connects to the panel's inclined ramp, and a return air shaft is located at the end of each section roadway. Because the downward-entry stope uses the layered exit tunnels as its entrance and exit, and the access stope is a single-ended mining operation, it lacks independent return air ducts. Local ventilation is used. Fresh air is forced into the access stope through an 11kW local ventilation fan installed in the exit tunnel, connected to a 500mm diameter flexible ventilation duct. Stale air is drawn to the return air shaft at the end of the section roadway through a 15kW local ventilation fan installed in the exit tunnel, connected to a 500mm diameter long-distance ventilation duct. Due to the small diameter and long distance of the available ventilation ducts, the air velocity in the access stope is low, and heat and smoke removal are difficult. Therefore, the mine optimized the ventilation of the downward-entry backfilling stope by adopting a grid-type duct ventilation method. Please refer to Figure 1-8 As shown, the specific steps for implementation are as follows:

[0034] S1. Design of a grid-type duct ventilation scheme for the downward-entry filling stope.

[0035] The down-entry filling stope is divided into 4 layers from top to bottom, each layer with a height of h=3m. Each layer is equipped with an ore outlet, one end of which connects to the section roadway and the other end connects to the down-entry stope. Each layer of the down-entry stope is mined every other layer, with a two-step recovery process.

[0036] The design uses the completed 1st layer ore outlet channel as the main return airway of the downward access filling stope.

[0037] The designed grid-type duct ventilation system for the mining area includes: 1. Layered access ventilation pipe 4. In-pipe check valve 17. Pipe inlet local ventilator 7. Horizontal ventilation pipe 5 perpendicular to the access side wall and connecting all accesses in the same layer. 6. Longitudinal ventilation pipe 6 perpendicular to the access bottom plate and connecting all vertical accesses. 7. Three-dimensional tees or three-dimensional crosses pre-embedded in the center of each access in the first layer. 8. Planar tees or planar crosses pre-embedded in the center of each access in layers below the first layer.

[0038] S2. Construct a three-way duct ventilation system (X, Y, Z) for the single-layer, one-step approach mining area.

[0039] After the first-stage, one-step approach and the second-stage mining are completed, when constructing the false bottom, a three-dimensional tee or four-way connector is pre-embedded in the center of the false bottom. The Z-port of the three-dimensional tee or four-way connector passes through the pre-reserved circular hole in the false bottom and faces downwards. The pipe opening is sealed with a plug. The X-port and Y-port are both higher than the upper surface of the false bottom. The X-port faces the approach entrance along the approach direction, and the Y-port faces the approach side wall vertically. The X-port connects to the ventilation pipe 4 of the first-stage approach and is laid to the outside of the filling retaining wall. A check valve 17 is installed inside the pipe, and the pipe opening is connected to a local ventilation fan 7. The Y-port connects to the transverse ventilation pipe 5 and extends vertically to the approach side wall. The pipe opening is sealed with a plug.

[0040] S3. Construct a three-way duct ventilation system (X, Y, Z) for a 1-layer, two-step approach mining area.

[0041] 1. When mining the first-step approach of the layered roadway 2, the strength of the backfill body meets the standard. When mining the second-step approach of the layered roadway 3, the transverse ventilation pipe 5 pre-embedded in the first-step approach is exposed from the side wall. The pipe plug is opened and the local ventilation fan 7 at the pipe opening of the first-step approach ventilation pipe is turned on, so that the sewage air in the second-step mining area can return through the transverse ventilation pipe 5 and the first-step approach ventilation pipe 4 of the layered roadway 1. After the second-step approach of the layered roadway 3 is mined, a three-dimensional tee or three-dimensional cross is pre-embedded in the false bottom in the center of the approach. The Z port of the three-dimensional tee or three-dimensional cross passes through the pre-reserved circular hole in the false bottom and faces downwards. The pipe opening is sealed with a plug. The X port and Y port are both higher than the upper surface of the false bottom. The Y port faces the side wall of the approach vertically. The transverse ventilation pipe 5 is connected to the exposed transverse ventilation pipe of the first step and is tightly connected. The X port is connected to the first-step approach ventilation pipe 4 and laid to the outside of the backfill retaining wall. A check valve is installed in the pipe and the pipe opening is connected to the local ventilation fan.

[0042] S4. Construct a Y and Z direction duct ventilation system for the access mining area below level 1, forming an integrated grid-type duct ventilation system.

[0043] When mining the 2-layer, one-step approach 9, the Z-port of the three-dimensional tee or four-way pre-embedded in the upper layer is exposed from the top plate of the approach. The pipe plug is opened so that the sewage air of the mining area of ​​the approach can return to the 1-layer mine exit 1 through the longitudinal ventilation pipe 6 and the 1-layer approach ventilation pipe 4. After the approach mining is completed, a plane tee or four-way is pre-embedded in the false bottom in the center of the approach. One end of the plane tee or four-way has a Z-port that passes through the pre-reserved circular hole in the false bottom and faces downward vertically. The pipe opening is sealed with a plug. The other end of the Z-port is connected to the longitudinal ventilation pipe 6 and is tightly connected to the Z-port exposed in the top plate. The Y-port is connected to the transverse ventilation pipe 5 and extends vertically to the side wall of the approach. The pipe opening is sealed with a plug.

[0044] During the 10-step mining of the two-layer, two-stage approach, the transverse ventilation pipe 5 pre-embedded in the first step is exposed from the side wall, and the Z-port of the three-dimensional tee or four-way pre-embedded in the upper layer is exposed from the top plate. The pipe plug is opened, so that the sewage air of the mining area of ​​this approach passes through the transverse ventilation pipe 5, the longitudinal ventilation pipe 6, and the ventilation pipe 4 of the first-layer approach. After the mining of the approach is completed, a plane tee or plane four-way is pre-embedded in the false bottom in the center of the approach. One end of the plane tee or plane four-way passes through the pre-reserved circular hole in the false bottom and faces downward vertically. The pipe opening is sealed with a plug. One end of the Z-port continues to the longitudinal ventilation pipe 6 and is tightly connected to the Z-port exposed in the top plate. The Y-port continues to the transverse ventilation pipe 5 and is tightly connected to the exposed transverse ventilation pipe of the first step.

[0045] When mining each lower-level access road, repeat steps S3 to S4 to eventually form a grid-type pipeline ventilation system for the mining area.

[0046] Compared with existing technologies, the grid-type duct ventilation method for down-entry filling stopes provided by this invention has the following advantages: 1) After the ventilation duct, local ventilator, and check valve in the top-level down-entry stope are installed, they can serve as the main return air channel for the lower-level down-entry stopes, eliminating the need for multiple relocations of the local ventilator and preventing airflow reversal. 2) For one-step or two-step down-entry mining in the layers below the top level, multiple parallel return air channels can be connected through the grid-type duct ventilation system, resulting in low wind resistance, high wind speed, and high efficiency. 3) It can effectively solve the problem of down-entry stopes lacking independent return air channels and difficulty in forming through-flow, ensuring the safety of stope operations, and reducing engineering workload and cost.

[0047] In a specific embodiment, the ventilation pipe, three-dimensional tee, three-dimensional cross, planar tee, planar cross, and pipe plug have the same net diameter to eliminate the local resistance caused by the sudden change in net diameter of the airflow in the pipe; the net diameter is 0.8~1.2mm to meet the safety clearance requirements of the trackless equipment in the access mining area, and at the same time reduce the frictional resistance of the airflow in the pipe.

[0048] As a specific embodiment, the ventilation pipes, three-dimensional tees, three-dimensional crosses, planar tees, planar crosses, and pipe plugs are all made of flame-retardant PVC, PP, or PPH material, thus possessing the characteristics of being lightweight, flame-retardant, pressure-resistant, and corrosion-resistant. They are particularly suitable for pre-embedding in the backfill of the mining area as reconstruction ventilation ducts; and the pressure that the pipe wall thickness can withstand should be greater than P=ρgh, where ρ is the bulk density of the filling slurry, in kg / m³. 3 g is the acceleration due to gravity, 9.8 m / s². 2 h represents the height of the filling material in a single inlet, in meters (m). Specifically, in the above implementation, calculations show that the pressure the ventilation duct wall thickness can withstand should be greater than P = ρgh = 1.87 × 10⁻⁶. 3 ×9.8×3=0.05MPa. The actual ventilation pipe wall thickness is 10mm, and the pressure resistance is 0.6MPa>0.05MPa, which meets the pressure requirements.

[0049] As a specific embodiment, the check valve 17 installed in the 1-layer inlet ventilation duct 4 is a butterfly check valve, and the nominal diameter of the check valve is consistent with the inner diameter of the ventilation duct, so as to facilitate installation. It opens quickly with the airflow when the local ventilation fan 7 at the ventilation duct opening is turned on, and closes quickly when the local ventilation fan 7 at the ventilation duct opening is turned off, to prevent the airflow in the duct from reversing.

[0050] As a specific embodiment, the local ventilation fan 7 installed at the inlet of the ventilation pipe 4 of the layered approach is a high-efficiency, low-energy, low-noise mine local ventilation fan of the same model with a mine safety mark. The fan power is 11kW, 15kW or 22kW, and the outer diameter of the fan inlet is consistent with the inner diameter of the ventilation pipe, so as to facilitate quick installation and meet the air volume requirements of the mining area.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A grid-type duct ventilation method suitable for down-entry filling stopes, characterized in that, Includes the following steps: S1. Design of a grid-type duct ventilation scheme for the downward-entry filling stope. The down-entry filling stope is divided into 1 to N layers from top to bottom, where N≥2. The height of each layer is h=3~5m. Each layer is equipped with an ore outlet. One end of the ore outlet connects to the middle section or segment roadway, and the other end connects to the down-entry stope. Each layer of the down-entry stope is mined every other layer, and the mining is carried out in two steps. The design uses the completed 1st layer ore outlet as the main return airway of the downward access filling stope. The designed grid-type duct ventilation system for the mining area includes: a single-layer access ventilation duct, an internal check valve, a local ventilator at the duct opening, a transverse ventilation duct perpendicular to the side wall of the access duct and connecting all access ducts in the same layer, a longitudinal ventilation duct perpendicular to the bottom plate of the access duct and connecting all access ducts in the vertical direction, a three-dimensional tee or three-dimensional cross-junction pre-embedded in the center of each access duct in the single-layer layer, and a planar tee or planar cross-junction pre-embedded in the center of each access duct in layers below the single-layer layer; S2. Construct a three-way duct ventilation system (X, Y, Z) for the single-layer, one-step approach mining area. After the first-stage, one-step backfilling is completed, during the construction of the false bottom, a three-dimensional tee or four-way connector is pre-embedded in the center of the false bottom. The Z-port of the three-dimensional tee or four-way connector passes through the pre-reserved circular hole in the false bottom and faces downwards. The pipe opening is sealed with a plug. The X-port and Y-port are both higher than the upper surface of the false bottom. The X-port faces the entrance of the entrance along the direction of the entrance, and the Y-port faces the side wall of the entrance perpendicularly. The X-port connects to the ventilation pipe of the first-stage entrance and is laid to the outside of the backfilling retaining wall. A check valve is installed inside the pipe, and the pipe opening is connected to a local ventilation fan. The Y-port connects to the transverse ventilation pipe and extends vertically to the side wall of the entrance. The pipe opening is sealed with a plug. S3. Construct a three-way duct ventilation system (X, Y, Z) for a 1-layer, two-step approach mining area. When the strength of the backfill body of the first-step approach in the first layer meets the standard, the transverse ventilation pipe pre-embedded in the first-step approach is exposed from the side wall during the mining of the second-step approach in the first layer. The pipe plug is opened and the local ventilation fan at the pipe opening of the first-step approach ventilation pipe is turned on, so that the sewage air in the second-step mining area can return through the transverse ventilation pipe and the first-step approach ventilation pipe in the first layer. After the mining of the second-step approach in the first layer is completed, a three-dimensional tee or three-dimensional cross is pre-embedded in the false bottom in the center of the approach. The Z port of the three-dimensional tee or three-dimensional cross passes through the pre-reserved circular hole in the false bottom and faces downward vertically. The pipe opening is sealed with a plug. The X port and Y port are both higher than the upper surface of the false bottom. The Y port faces the side wall of the approach vertically. The transverse ventilation pipe is connected to the exposed transverse ventilation pipe of the first step and is tightly connected. The X port is connected to the approach ventilation pipe and laid to the outside of the backfill retaining wall. A check valve is installed in the pipe and the pipe opening is connected to the local ventilation fan. S4. Construct a Y and Z direction duct ventilation system for the access mining area below level 1, forming an integrated grid-type duct ventilation system. When mining the first step of the access road below the first layer, the Z-port of the three-dimensional tee or four-dimensional cross passage pre-embedded in the upper layer is exposed by the roof of the access road. The pipe plug is opened so that the sewage air in the access road can return to the ore exit road of the first layer through the longitudinal ventilation pipe and the ventilation pipe of the first layer access road. After the access road is mined out, a plane tee or plane four passage is pre-embedded in the false bottom in the center of the access road. One end of the plane tee or plane four passage has a Z-port that passes through the pre-reserved circular hole in the false bottom and faces downwards. The pipe opening is sealed with a plug. The other end of the Z-port is connected to the longitudinal ventilation pipe and is tightly connected to the Z-port exposed in the roof. The Y-port is connected to the transverse ventilation pipe and extends vertically to the side wall of the access road. The pipe opening is sealed with a plug. When mining in two steps below the first layer, the transverse ventilation pipe pre-embedded in the first step is exposed from the side wall, and the Z-port of the three-dimensional tee or three-dimensional quadrilateral pre-embedded in the upper layer is exposed from the top plate. The pipe plug is opened so that the sewage air in the mining area of ​​the first layer can return through the transverse ventilation pipe, the longitudinal ventilation pipe, and the ventilation pipe of the first layer approach. After the access route is completed, a plane tee or plane cross is pre-embedded in the false bottom in the center of the access route. One end of the plane tee or plane cross passes through the pre-reserved circular hole in the false bottom and faces downwards. The pipe opening is sealed with a plug. One end of the plane tee or plane cross is connected to the longitudinal ventilation pipe and is tightly connected to the exposed Z-port in the roof. The Y-port is connected to the transverse ventilation pipe and is tightly connected to the exposed transverse ventilation pipe in the first step. When mining each lower-level access road, repeat steps S3 to S4 to eventually form a grid-type pipeline ventilation system for the mining area.

2. The grid-type duct ventilation method for down-entry filling stopes according to claim 1, characterized in that, The ventilation duct, three-dimensional tee, three-dimensional cross, planar tee, planar cross, and pipe plug all have the same net diameter, which is 0.8~1.2mm.

3. The grid-type duct ventilation method for down-entry filling stopes according to claim 1, characterized in that, The ventilation pipes, three-dimensional tees, three-dimensional crosses, planar tees, planar crosses, and pipe plugs are all made of flame-retardant PVC, PP, or PPH materials, and the pressure that the pipe wall thickness can withstand should be greater than P=ρgh, where ρ is the bulk density of the filling slurry, g is the gravitational acceleration, and h is the height of the filling body in a single inlet.

4. The grid-type duct ventilation method for down-entry filling stopes according to claim 1, characterized in that, The check valve installed inside the ventilation duct of the first-level approach is a butterfly check valve, and the nominal diameter of the check valve is consistent with the inner diameter of the ventilation duct.

5. The grid-type duct ventilation method for down-entry filling stopes according to claim 1, characterized in that, The local ventilation fan installed at the inlet of the ventilation duct in the first layer of the access road is a high-efficiency, low-energy, low-noise mine local ventilation fan of the same model with a mine safety mark. The fan power is 11kW, 15kW or 22kW, and the outer diameter of the fan inlet is consistent with the inner diameter of the ventilation duct.

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