A multi-machine combined mining method for a gently inclined ore body with an interlayer

Abstract

The application discloses a kind of slow incline broken non-coal ore body multi-mechanical combined mining method containing interlayer;It relates to the technical field of ore mining, comprising the following steps: S1, according to the ore Proctor coefficient, the mechanical mining equipment of upper and lower layers of ore body is selected, the corresponding mechanized non-blasting mining method used in upper and lower layers of ore body is determined;S2, the upper and lower layers of ore body are divided into multiple panels along the strike, and the corresponding mining preparation cutting engineering is arranged according to the mechanical mining method determined by the upper and lower layers of ore body;S3, the corresponding stoping and ore drawing engineering is carried out according to the mechanical mining method determined by the upper and lower layers of ore body;S4, the corresponding filling engineering is carried out according to the mechanical mining method determined by the upper and lower layers of ore body.The present application is based on the optimization and improvement of the single mining machine fully mechanized mining and the excavation anchor integrated mining method of prior art, and the two kinds of mechanical equipment can be used simultaneously to stop the slow incline parallel multilayer ore vein containing interlayer, realize separate mining and separate transportation, have the characteristics of large production capacity, high safety, small dilution loss, etc., and are especially suitable for the stoping of parallel ore body group with large production scale and the need for separate mining and separate transportation.

Description

Technical Field

[0001] This invention relates to the field of ore mining technology, and in particular to a multi-mechanical combined mining method for gently inclined fractured ore bodies containing interlayers. Background Technology

[0002] Currently, traditional drill-and-blast methods are often used to mine gently dipping, fractured ore bodies containing interlayers. Whether using single-stage or layered blasting, the difficulty in precisely controlling the blasting boundaries easily leads to the mixing of waste rock interlayers into the ore, causing dilution, and also results in incomplete ore recovery and losses. In recent years, mechanical mining methods have been widely used in non-coal mining, but most currently employ a single mechanical mining method. This method still has limitations in identifying ore bodies and interlayers, inevitably resulting in the mixing of large amounts of interlayers into the ore or the discarding of ore along with waste rock, causing significant dilution. Furthermore, single mechanical mining methods are poorly adaptable to changes in ore body morphology. When encountering multiple layers and complex, variable ore bodies, the cutting trajectory of mechanical mining equipment cannot be flexibly adjusted to adapt to changes in ore body boundaries. Therefore, whether using traditional drill-and-blast methods or single mechanical mining methods, the presence of waste rock interlayers often leads to significant losses and dilution, resulting in resource waste.

[0003] Meanwhile, because the types of ore on both sides of the interlayer are different, mixed mining often increases the difficulty of subsequent ore beneficiation. Therefore, existing mining methods cannot meet the requirements of multi-layer simultaneous mining and separate mining and transportation of multiple types of ore bodies containing interlayers. Summary of the Invention

[0004] To address the need for large-scale parallel orebody mining that requires separate extraction and transportation, this application provides a multi-mechanical combined mining method for gently dipping fractured orebody containing interlayers.

[0005] This application provides a multi-mechanical combined mining method for gently dipping fractured ore bodies containing interlayers, employing the following technical solution:

[0006] A multi-mechanical combined mining method for gently dipping fractured ore bodies containing interlayers, characterized by comprising the following steps:

[0007] S1. Select mechanical mining equipment for the upper and lower layers of the ore body based on the Protodyakonov coefficient of the ore.

[0008] S2. Divide the upper and lower ore bodies into multiple panels along the strike, and arrange the corresponding mining preparation and cutting works according to different mechanical mining methods;

[0009] S3. Conduct corresponding mining and ore extraction projects according to different mechanical mining methods;

[0010] S4. Conduct the corresponding backfilling work according to different mechanical mining methods.

[0011] Optionally, in step S1, when the Protodyakonov coefficient f ≤ 4, a fully mechanized mining machine is used; when the Protodyakonov coefficient f > 4, a roadheader-anchor integrated mining machine is used.

[0012] Optionally, in step S2, when using a fully mechanized mining machine, a trackless transport roadway is arranged along the strike at the bottom of each section of the ore body in the panel. An uphill crossroads is arranged perpendicular to the strike of the ore body in the trackless transport roadway, and a conveyor belt uphill is arranged pseudo-inclined along the dip direction of the ore body. At the same time, a flat slope section is added to the conveyor belt uphill, and a chute is arranged to connect with the ore body belt transport roadway. A return air roadway and a transport roadway are arranged along the dip at the top of the ore body, and a ore body belt transport roadway is arranged horizontally along the sections at the bottom of the ore body.

[0013] Optionally, in step S2, when using a tunneling and anchoring machine for mining, the panel is divided into multiple sections from top to bottom, and each section is further divided into strips.

[0014] The trackless transport roadway, belt conveyor roadway, and ramp for personnel and materials are excavated near the bottom of the ore layer. Multiple transfer belts are excavated through the mining preparation to the boundary of the ore body in the ore panel. Then, the panel connecting roadway is excavated. On the panel connecting roadway, the layered return air is excavated along the working face towards the middle of the panel, and the backfill is carried out uphill to the top elevation. After that, the panel connecting roadways of each section are excavated from bottom to top. Finally, the strip mining is carried out using a tunneling and anchoring machine.

[0015] Optionally, if the dip angle of the ore body is ≤9°, the strips are arranged along the dip direction of the ore body; if the dip angle of the ore body is >9°, in order to meet the requirements for equipment movement, the strips are arranged in a pseudo-dipping manner along the dip direction of the ore body.

[0016] Optionally, in step S3, when using a fully mechanized mining machine, the ore layer is mined from bottom to top by opening a cut in the fully mechanized mining face along the dip direction using a mining machine and hydraulic supports; the mining machine operates continuously from bottom to top along the dip direction; a scraper conveyor equipped with the working face transports the cut ore to the conveyor belt in the transport roadway for transfer, and then the ore is transferred to the conveyor belt uphill via the conveyor belt level roadway, and then transferred to the panel centralized conveyor belt transport roadway via the conveyor belt uphill and chute, and finally transported to the main shaft yard; after the hydraulic supports move up the working face, the goaf is supported by single hydraulic props, and the single hydraulic props in the goaf are not recycled.

[0017] Optionally, in step S3, when the Protodyakonov coefficient f > 4, a roadheader-anchor integrated machine is used for strip mining, and ore is fed onto a bridge-type belt conveyor, with a retractable belt conveyor installed behind it for ore extraction; each layer first mines the central strip from the bottom plate to the top plate of the panel and provides permanent support, which serves as the panel's layered return air and backfilling uphill; after all strips in the panel's layer are backfilled, the next layer mining continues; the ore is transported by belt to the panel's central belt conveyor roadway.

[0018] Optionally, in step S4, when using a fully mechanized mining machine, the goaf can be filled after the working face has advanced an appropriate distance from the opening. The filling pipeline enters the goaf from the surface through filling boreholes, into the return air gate, return air roadway, and return air chute of the panel roof.

[0019] Optionally, in step S4, when using a tunneling and anchoring machine for strip mining, after the segmented strip mining is completed, a filling retaining wall is built at the end of the strip, and filling pipes are laid. The filling pipes are filled in sequence according to the trackless transport roadway, trackless transport through-passage, panel connecting roadway, and top of the strip mining area. After the strip mining area is filled once, the filling water precipitated at the top is extracted by a submersible pump and discharged into the roadway ditch through a water pipe.

[0020] In summary, this application includes the following beneficial technical effects:

[0021] This invention is an optimization and improvement of the existing mining method that uses a single mining machine for fully mechanized mining and a tunneling and anchoring integrated mining machine. It can simultaneously use two types of mechanical equipment to mine gently inclined parallel multi-layered ore veins with interlayers, realizing separate mining and transportation. It has the characteristics of large production capacity, high safety, and low dilution loss. It is particularly suitable for the mining of parallel ore body groups with large production scale and the need for separate mining and transportation. Attached Figure Description

[0022] Figure 1 This is a cross-sectional view of the fully mechanized mining of ore layer b in the embodiment;

[0023] Figure 2 yes Figure 1 Enlarged view of section A;

[0024] Figure 3 This is a cross-sectional view of the fully mechanized mining of ore layer a in the embodiment;

[0025] Figure 4 yes Figure 3 Section III-III;

[0026] Figure 5 yes Figure 1 Section IV-IV.

[0027] Explanation of reference numerals in the attached figures:

[0028] 1. Belt conveyor cross-section of ore seam; 2. Connecting roadway in ore seam A panel; 3. Convex / retractable belt conveyor; 5. Layered return air filling uphill section in ore seam A panel; 7. Trackless haulage cross-section of ore seam; 9. Cross-sections of ore seams A and B; 10. Trackless haulage roadway; 11. Belt conveyor roadway in ore seam A; 12. Belt conveyor roadway in ore seam B; 15. Inclined ramp; 19. Opening cut of fully mechanized mining face in ore seam B; 20. Cross-section of ore seam B; 21. 22. Transition support; 23. Hydraulic support; 24. B-seam return airway; 25. B-seam transport roadway; 26. Scraper conveyor; 27. Transfer conveyor; 28. Mining machine; 29. ​​B-seam conveyor belt uphill; 30. B-seam ore pass; 31. Transfer crusher; 32. B-seam belt conveyor level roadway; 33. B-seam transfer belt level roadway; 34. Safety pillar; 35. Return airway; 36. Return air gate. Detailed Implementation

[0029] The following is in conjunction with the appendix Figure 1-5 This application will be described in further detail.

[0030] This application discloses a multi-mechanical joint mining method for gently inclined fractured ore bodies with interlayers. First, the upper and lower ore bodies are divided into multiple panels along the strike. Then, two mining methods are adopted according to the different Protodyakonov coefficients of the ore.

[0031] When the Protodextrin coefficient f ≤ 4, the fully mechanized mining method using mining machines is adopted;

[0032] The layout of the preparatory works is as follows: trackless transport roadways are arranged along the strike at the bottom of each section of the ore seam in the panel area; return air roadways and transport roadways are arranged along the dip at the top of the ore seam; and belt conveyor roadways are arranged horizontally along each section at the bottom of the ore seam. The cross-section of the return air roadway, transport roadway, and cut-off is 6.0m × 4.0m, with a rectangular cross-section.

[0033] Mining operations: The ore seam is mined from bottom to top by cutting an opening in the fully mechanized mining face along the dip direction using mining machines and hydraulic supports; the mining machines operate continuously from bottom to top along the dip direction; the scraper conveyor at the working face transports the cut ore to the conveyor belt in the transport roadway for transfer, and then the ore is transferred to the conveyor belt uphill via the conveyor belt level roadway, and then to the panel's centralized conveyor belt transport roadway via the conveyor belt uphill and ore pass, and finally to the main shaft yard; after the hydraulic supports move up the working face, the goaf is supported by individual hydraulic props, and the individual hydraulic props in the goaf are not retrieved.

[0034] Backfilling construction: A 71% concentration slurry with a ratio of phosphogypsum to tailings of 3:1 to 3:2 is used for cementing backfilling. Backfilling can begin after the working face has advanced an appropriate distance from the initial cut. Backfilling pipelines enter the goaf from the surface through backfilling boreholes, then through the return air gate, return air roadway, and return air chute in the roof of the working face.

[0035] When the Protodextrin coefficient f of the ore is greater than 4, strip mining with an integrated tunneling and anchoring machine is adopted.

[0036] The layout of the preparatory work: The panel is divided into multiple sections from top to bottom, and each section is further divided into strips. If the dip angle of the ore body is ≤9°, the strips are arranged along the dip direction of the ore body. If the dip angle of the ore body is >9°, the strips are arranged in a pseudo-dipping manner along the dip direction of the ore body to meet the requirements for equipment movement. As a preferred option, the strike length of the panel is 150~200m, the height of the panel is 200m, the vertical height of the section is 50m, and the width of the strip is 6m.

[0037] Excavate trackless transport roadways, belt conveyor roadways, and ramps for personnel and materials to enter and exit near the bottom of the ore layer; excavate multiple transfer belts through the ore body to the boundary of the ore panel, then excavate the panel connecting roadway, and excavate the layered return air and backfill uphill to the top elevation along the working face on the panel connecting roadway; after completion, excavate the panel connecting roadway of each section from bottom to top;

[0038] Mining operations: When the Protodyakonov coefficient f > 4, a roadheader-anchor integrated machine is used for strip mining, with ore being fed onto a bridge-type belt conveyor and then discharged via a retractable belt conveyor. Each layer is first mined from the bottom to the top of the panel, with the central strip being permanently supported and used as the panel's stratified return air and backfilling uphill. After all strips in the panel's strata are backfilled, the next layer of mining continues. The ore is transported by belt conveyor to the panel's central belt conveyor roadway.

[0039] Furthermore, if the ore body thickness is >5m, then layered mining should be considered, and the sequence of layered mining should be determined based on the stability of the surrounding rock of the roof.

[0040] Furthermore, when mining two ore layers simultaneously, the frequency and duration of mining equipment operation in the same vertical space should be reduced.

[0041] Preferably, the layer height is 4.5m, and the strip mining sequence is 2 mins every 1.

[0042] Backfilling construction: A 71% concentration slurry with a ratio of phosphogypsum to tailings of 3:1 to 3:2 is used for cementing and backfilling. After the segmented strip mining is completed, a backfilling retaining wall is built at the end of the strip, and backfilling pipes are laid. The backfilling pipes are filled in sequence according to the trackless transport roadway, trackless transport through vein, panel connecting roadway, and top of the strip stope. After the strip stope is filled in one go, the backfilling water that precipitates from the top is pumped out with a submersible pump and discharged into the roadway ditch through water pipes.

[0043] Take a phosphate mine in Guizhou as an example.

[0044] The phosphate ore body is a gently dipping, medium-thick ore body, mainly occurring at elevations from 0m to 800m. The ore body consists of two layers: the upper layer, layer B, dips at 15.2° with an average thickness of 9.13m, and is composed of calcareous phosphate rock; the lower layer, layer A, dips at 15.2° with an average thickness of 16.95m, and is composed of siliceous calcareous phosphate rock. Separate mining and transportation must be considered during extraction. An interlayer exists between layers A and B, with an average thickness of 3.99m. The roof, ore body, and interlayers are predominantly composed of fine-grained dolomite, which is hard, brittle, and fragmented, exhibiting poor stability; the floor is composed of clayey sandstone, which has better stability.

[0045] The specific implementation steps are as follows:

[0046] 1) Section division

[0047] The a and b ore layers are divided into a middle section with a height of 200m. The middle section is divided into panels along the strike. When mining the a ore layer, 6 panels are arranged in the mining area. Each panel is divided into 4 sections from top to bottom. Each section has a span of 168m, a diagonal length of 284m, and a vertical height of 50m. When mining the b ore layer, the strike length of the panel is about 150~200m, the height of the panel is 200m, and the dip length is about 760m.

[0048] 2) Ore body stratification

[0049] In the vertical plane, the A-seam is mined in one section (span of 168m, slope length of 284m, vertical height of 50m) from bottom to top. The ore body in the section is mined in layers along the dip. The A-seam (lower layer of the ore body) is divided into 4 layers with a layer height of 4m.

[0050] In the B ore layer, from left to right in the plane, one section is mined at a time (span of 162m, slope length of 762.8m, vertical height of 200m). The B ore layer (the upper layer of the ore body) is divided into two layers, with a layer height of 4.5m.

[0051] 3) Mining and Cutting Engineering

[0052] The main mining and cutting works are all located within the vein. The A-seam development system involves excavating 400m, 500m, and 600m trackless transport roadways (10), a 400m belt conveyor roadway (11), and a ramp (400m-600m elevation, used for personnel and material access) near the A-seam floor. Two ore transfer belt conveyors are excavated through vein 1 to the boundary of the A-seam panel. Then, a 400m panel connecting roadway (2) is excavated. Along the pseudo-sloping working face (9°) on the 400m panel connecting roadway 2, a stratified return airway and backfilling ramp is excavated towards the center of the panel, reaching an elevation of 5 to 600m. After completion, 450m, 500m, 550m, and 600m ore panel connecting roads (2) are excavated from bottom to top. Finally, a strip mining operation is carried out using the EJM600 / 4-2 roadheader / anchor machine.

[0053] The B-seam mining preparation and cutting project mainly includes the B-seam return airway 23, the B-seam transport roadway 24, and the B-seam fully mechanized mining face opening 19. The return airway 23, transport roadway 24, and opening all have a rectangular cross-section of 6.0m × 4.0m. Trackless transport roadways 10 are arranged along the strike at the bottom of the A-seam at 400m, 500m, and 600m respectively. The return airway 23 and transport roadway 24 are arranged along the dip at the top of the B-seam. A 500mb B-seam belt conveyor roadway 31 is arranged horizontally at 500m along the bottom of the B-seam. The B-seam ore is transferred to the B-seam conveyor belt incline 28 via the 500mb B-seam conveyor belt incline 34, and then transferred to the 400mb B-seam belt conveyor roadway 12 via the B-seam conveyor belt incline 28 and the B-seam ore pass 29, finally transporting the ore to the main shaft yard.

[0054] 4) Retrieved

[0055] The A-seam is mined using an EJM600 / 4-2 roadheader-anchor integrated machine in a strip mining manner, with ore fed onto a bridge-type belt conveyor and then discharged via a retractable belt conveyor. The strips are arranged along a pseudo-dipping direction at a 9° angle, with a 2-strip interval between each strip. A total of 28 strips are arranged within the panel. Mining of each layer begins with the 16th strip in the center, from the 400m elevation to the 600m elevation, and permanent support is provided. This serves as the layered ventilation and backfilling for the A-seam panel. After all strips within a layer are backfilled, mining of the next layer begins.

[0056] Mining of the B ore layer proceeds upwards from the bottom of the fully mechanized mining face through cut hole 19. An MG900 / 2240-WD AC-powered traction mining machine with hydraulic supports (model ZC12000 / 30 / 52D, support center-to-center spacing 1750mm, working resistance 12000KN) is used for this process, with a cutting depth of approximately 0.8m. One cut (approximately 0.8m wide) along the strike constitutes one cycle, with two cuts per shift, completing two cycles. Mining machine 27 operates continuously upwards along the dip. An SGZ1000 / 1400 scraper conveyor 25 (length 150m~200m) transports the cut ore to the conveyor belt in the B ore layer transport roadway 24 for further transfer. As the working face moves upwards, hydraulic supports 22 are used to support the roof in the goaf using DW45-200 / 110(G) high-titanium alloy steel single hydraulic props, with a row spacing and interval of 6m. After the working face advances for 4 cycles (not exceeding 7 cycles) from the start of the cut, the goaf can be filled. Individual hydraulic props in the goaf are not recycled.

[0057] It is worth noting that when mining layers A and B simultaneously, from a management and design perspective, the frequency and duration of mining equipment operating in the same vertical space should be minimized to avoid mutual interference between equipment operations that could cause instability and damage to the ore and rock.

[0058] 5) Filling

[0059] The backfilling uses a 71% concentration slurry with a ratio of phosphogypsum to tailings of 3:1 to 3:2. After each strip of the A-seam is mined, a 1200mm thick backfill retaining wall is constructed at the end of each strip. The backfilling pipeline is laid as follows: 500m trackless haulage roadway 18 → 500m trackless haulage channel 7 → 500m connecting roadway 8 for the ore panel → top of the strip stope → backfilling. After the strip stope is fully filled, the backfill water precipitated from the top is pumped out using a submersible pump and discharged into the roadway drainage ditch through water pipes.

[0060] Starting from the opening of the B ore layer, after the working face has advanced a suitable distance, open-type backfilling can be carried out on the goaf. The backfilling pipeline enters the goaf from the surface through the backfilling borehole, through the 600m return air gate 36, the 600m return air roadway 35, and the return air roadway 23, filling the goaf (150~200m long and 3.2m wide) for 4 working cycles at a time.

[0061] The present invention has an overall panel production capacity of 18,000 t / d for the a and b ore layers, a loss rate of 8%, a dilution rate of 5%, and a 1,000-ton mining-to-cut ratio of 0.99 kt / m. Compared with other non-mechanical mining methods, the panel production capacity is greatly increased and the mining-to-cut ratio is greatly reduced without a significant increase in the dilution rate.

[0062] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A multi-mechanical combined mining method for gently inclined fractured ore bodies with interlayers, characterised in that The method comprises the following steps: S1, selecting mechanical mining equipment of upper and lower layers of the ore body according to the Protsenko coefficient of the ore, and determining the corresponding mechanical non-blasting mining method of the upper and lower layers of the ore body; S2, dividing the upper and lower layers of the ore body into multiple panels along the strike, and arranging the corresponding mining and cutting engineering according to the determined mechanical mining method of the upper and lower layers of the ore body; S3, carrying out the corresponding stoping and ore drawing engineering according to the determined mechanical mining method of the upper and lower layers of the ore body; S4, carrying out the corresponding filling engineering according to the determined mechanical mining method of the upper and lower layers of the ore body; In step S1, when the Protsenko coefficient f of the ore is less than or equal to 4, the fully mechanized mining machine is used for mining, and when the Protsenko coefficient f is greater than 4, the excavating and anchoring integrated machine is used for mining; In step S2, when the fully mechanized mining machine is used for mining, a trackless transport roadway is arranged along the strike at each sublevel layer floor of the panel, an uphole is arranged vertically to the strike direction of the ore body in the trackless transport roadway, a false inclined belt uphole is arranged along the ore body dip direction, a section of flat slope section is additionally arranged in the belt uphole, and a chute is arranged to communicate with the belt transport roadway; a return air crossheading and a transport crossheading are arranged along the dip direction at the ore layer roof, and a belt transport roadway is arranged horizontally at the ore layer floor; In step S2, when the excavating and anchoring integrated machine is used for mining, multiple sections are divided from top to bottom in the panel, and strips are divided in the sections; A trackless transport roadway, a belt transport roadway and an inclined ramp for personnel and material access are excavated near the ore layer floor; a plurality of transfer belt passageways are excavated to the ore body boundary of the panel, then a panel connecting passage is excavated, and a panel layer return air and filling uphole is excavated to the roof elevation along the working face in the panel; after completion, the panel connecting passages of each section are excavated from bottom to top, and finally the strip type stoping is carried out by using the excavating and anchoring integrated machine.

2. A multi-machine combined mining method for a flat- dipping fractured ore body with an interlayer according to claim 1, characterized in that: If the ore body dip angle is less than or equal to 9°, the strips are arranged along the ore body dip direction, and if the ore body dip angle is greater than 9°, the strips are arranged in a false inclined manner along the ore body dip direction to meet the equipment walking requirements.

3. A multi-machine combined mining method for a flat- dipping fractured ore body with an interlayer according to claim 2, characterized in that: In step S3, when the Protsenko coefficient f of the ore is less than or equal to 4, the fully mechanized mining machine is used for mining, and the ore layer is cut along the dip direction from the fully mechanized mining working face to carry out stoping from bottom to top by using the mining machine and hydraulic support; the mining machine continuously works from bottom to top along the dip direction; the cut ore is transported to the belt in the transport crossheading by using the supporting scraper conveyor, and then is transferred to the belt uphole through the transfer belt roadway, and is transferred to the panel concentrated belt transport roadway through the belt uphole and the chute, and is transported to the main shaft yard; the single hydraulic support in the goaf supports the roof after the hydraulic support moves with the working face, and the single hydraulic support in the goaf is not recycled.

4. A multi-machine combined mining method for a flat-lying fractured ore body with an interlayer according to claim 3, characterized in that: In step S3, when the Protsenko coefficient f of the ore is greater than 4, the excavating and anchoring integrated machine is used for strip type mining, the ore is dropped to the bridge type belt conveyor, and the rear is provided with a telescopic belt ore drawing device; the central strip of each layer is first stoped from the panel floor to the roof, and is permanently supported, serving as the panel layer return air and filling uphole; after the filling of all strips in the panel layer is completed, the stoping of the next layer is started; The ore is transported to the panel concentrated belt transport roadway by the belt.

5. A multi-machine combined mining method for a flat- dipping fractured ore body with an interlayer as claimed in claim 4, characterized in that: In step S4, when using mining machine fully mechanized mining, after advancing a proper distance from the open-off cut, the goaf can be filled; the filling pipe enters the goaf through the filling borehole from the surface, the return air stone gate, the return air roadway and the return air crossheading of the roof of the panel.

6. A multi-machine combined mining method for a flat- dipping fractured ore body with an interlayer as claimed in claim 5, characterized in that: In step S4, when using the combined excavating and anchoring machine, after the sublevel strip mining is completed, the filling retaining wall is built at the end of the strip, and the filling pipe is laid; the filling pipe fills in turn according to the sequence of the trackless haulage roadway, the trackless haulage crossheading, the panel connecting passage and the top end of the strip mine; after filling the strip mine once, the filling water separated from the top is pumped out by a submersible pump and discharged into the water channel of the roadway through the water pipe.

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