A downward approach filling mining method with reserved interval pillars

Abstract

The present invention discloses a downward approach filling mining method with reserved interval pillars. The stope is divided and the mining and cutting engineering is arranged in the manner of the downward approach filling mining method. Mining is carried out in layers from top to bottom in the middle section. The ore body in the layers is divided into approaches and mined from the center to the two wings. During approach mining, the first mining approach is constructed from the vein lane perpendicular to the direction of the ore body to the boundary of the upper wall of the ore body. Then, interval-type spalling mining is carried out on the side of the approach to form blasting compensation space for subsequent approach mining. Pillars are left at intervals between the spalling mining areas from the boundary of the vein lane. The approach is then filled and topped. During approach filling, a filling retaining wall is constructed at the outer boundary of the spalling mining area to reserve blasting compensation space for the next approach mining. The present invention has the advantages of safe operation, large stope production capacity, high efficiency, and low cost.

Description

Technical Field

[0001] The invention belongs to the technical field of mine mining, and in particular relates to a downward approach filling mining method with reserved interval ore pillars. Background Art

[0002] Backfill mining involves filling the goaf with filler material while ore is being dropped, transported, and processed. The purpose of backfilling is to support the rock on either side of the goaf and create a foundation for continued stratified mining above. It is suitable for deposits where the ore and surrounding rock are unstable and large exposed areas are not permitted; where the surface requires protection; where rare and precious metal or high-grade ores are present; where sulfide deposits are prone to spontaneous combustion; and where the mineral deposits have complex geological conditions.

[0003] Because backfill mining maximizes mineral resource recovery and protects the underground and surface environments, it has been widely used in nonferrous and precious metal mines, particularly in recent years, driven by advancements in backfill materials, processes, pipeline transportation equipment, and technology. With the continuous reduction of backfill costs and the continued rise in mineral product prices, backfill mining, due to its irreplaceable advantages, is increasingly being used in mines such as coal and iron ore, where backfilling is traditionally unsuitable.

[0004] Among the many filling mining methods, the downward approach filling mining method is currently the most widely used mining method in my country's metal and non-metal mines. This method is a mining method that sequentially mines and fills layers from top to bottom, and operates under the protection of artificial false roofs in layers in the form of tunnel approaches. The downward approach filling mining method is mainly suitable for ore bodies with very unstable ore rocks, high ore grades and good economic value. The advantage of this method is that the roof of the workplace is artificially assumed, which is safer and more reliable, and the ore loss rate and ore depletion rate are low. However, the existing downward approach filling mining method also has the following main shortcomings:

[0005] (1) Low mining efficiency and high mining costs. Currently, all access mining is carried out by blasting the ore through tunnel excavation. The blasting is difficult and the advance per excavation is low, so the mining efficiency is low, which restricts the mining production capacity. At the same time, tunnel blasting requires the construction of a large number of blastholes, which consumes a lot of manpower and pyrotechnic materials, and the mining cost is relatively high.

[0006] (2) The quality of the filling body in the mining area is difficult to guarantee. The slow water filtration rate directly affects the filling strength and the roof connection rate. Since the approach mining method only has one filling wall at the entrance to the approach for water filtration, the water filtration capacity is limited, resulting in a long solidification time of the filling body and low filling strength. At the same time, the water in the filling body is not discharged in time, which also leads to poor filling and roof connection effect, affecting the safety of the lower layer mining operation.

[0007] (3) The access road specifications are narrow and the production capacity is limited. Due to the low strength of the roof filling body, at the same time, the parallel advancement of each access road in the upper layer and the difference in filling time lead to the formation of weak surfaces in the filling body between each access road. The steel bar welding points are between the weak surfaces, which increases the probability of the filling body collapsing. Therefore, the access road specifications should not be too large when mining in the lower stope, which will result in limited stope production capacity and increased filling times. Summary of the Invention

[0008] In response to the problems existing in the above-mentioned existing downward approach filling mining method, the present invention discloses a downward approach filling mining method with reserved interval pillars, which includes the following steps:

[0009] Step 1: Divide the stope and arrange the mining and cutting works according to the downward approach and filling mining method. Mining is carried out in layers from top to bottom in the middle section. Within the layers, a stope connecting road is constructed from the outside of the vein in a segmented level road to the boundary of the ore body footwall. Then, a vein road is constructed from the stope connecting road in the footwall of the ore body to the boundaries of both sides of the stope. The ore body within the layers is divided into approaches for mining.

[0010] Step 2: Mining is carried out from the center to the two wings within the stope layer. At the center of the stope layer, the first mining approach is constructed from the vein lane perpendicular to the ore body strike direction to the boundary of the ore body hanging wall. Then, interval spalling is carried out on both sides of the first mining approach to form blasting compensation space for subsequent approach mining. Pillars are left at intervals between the spalling mining areas from the boundary of the vein lane. The roof of the approach and spalling mining area is supported by anchor cables + mesh. After the spalling mining is completed, a steel mesh is laid on the bottom plate of the approach. The steel mesh is hung on the anchor cables of the approach roof with hangers. Then, filling retaining walls are erected at the outer boundary of the spalling area and the approach entrance, and the approach is filled and connected to the roof.

[0011] Step 3: After the filling and maintenance of the first mining route is completed, the two adjacent routes are mined at the same time. First, the route is constructed from the vein lane perpendicular to the ore body strike direction to the boundary of the upper wall of the ore body, and then the interval-type spalling mining is carried out on the side of the route close to the original rock to form a blasting compensation space for the subsequent route mining. Pillars are left at intervals between the spalling mining areas from the boundary of the vein lane. The roof of the route and the spalling mining area is supported by anchor cables + mesh. After the spalling mining is completed, the pillars on the side of the filling body are successively recovered from the upper wall of the ore body to the lower wall. In order to ensure the stability of the intersection of the route opening and the vein lane, the pillars at the boundary of the vein lane are not recovered. Then, a steel mesh is laid on the bottom plate of the route, and the steel mesh is hung on the anchor cables of the route roof with hangers. Filling retaining walls are erected at the outer boundary of the spalling area and the route opening, and the route is filled and topped.

[0012] Step 4: After the filling and curing of the access road mined in step 3 is completed, the two access roads on one side of the filled access road are mined again. The mining and filling methods are the same as those in step 3. This cycle is repeated until the mining of the entire first layer is completed.

[0013] Step 5. After the first layer is mined, the next layer is mined. The layer mining and filling method is the same as steps 2 to 4. This cycle is repeated until the mining of the entire stope is completed. At this time, the steel mesh laid on the bottom plate of each layer access road is hung on the steel mesh of the previous layer through the hanger.

[0014] Furthermore, during the layered mining, the first mining routes of the two upper and lower adjacent layers are staggered by 1 / 2 of the route width.

[0015] Furthermore, the access road is an upslope of 0.3% from the lower wall to the upper wall, the length of the access road is the thickness of the ore body, and the cross-sectional specifications of the access road are determined according to the engineering geological conditions of the ore body rock and the magnitude of the ground stress.

[0016] Furthermore, when the steel mesh is laid, both ends of each steel bar in the width direction of the first layered approach are folded upward at the approach wall and a length of not less than 1.5m is reserved, and the reserved lengths of two adjacent steel bars are staggered, with a length difference of 0.5m; when laying steel mesh in other approaches within the layer, each steel bar in the width direction of the approach is folded upward at the approach wall on the side of the original rock and a length of not less than 1.5m is reserved, and the reserved lengths of two adjacent steel bars are staggered, with a length difference of 0.5m. At the same time, the steel bars reserved for laying the steel mesh in the previous approach close to the filling body are welded to the steel mesh laid this time, and the welding points are staggered so that the welding points of the steel bars are staggered with the weak surfaces between the filling bodies.

[0017] Furthermore, the width of the spall mining is 1 / 2 of the width of the approach, the height of the spall mining is the height of the approach, and the length of a single spall mining area is greater than or equal to 3 times the single-cycle footage of the approach; the width of the pillar is 1 / 2 of the width of the approach, the length is not greater than the single-cycle footage of the approach, and the height is equal to the height of the approach.

[0018] Furthermore, when mining in layers, the first mining approach adopts the tunneling method for mining, and the face is the only free face and compensation space for blasting; when mining with other approaches, when the side of the filling body is a pillar, mining is carried out by tunneling, and the face is the only free face and compensation space for blasting. When the side of the filling body is the spall area of ​​the previous approach mining, the spall area is used as the main free face and compensation space for lateral blasting and collapse of the mine. At this time, the filling retaining wall on the side of the filling body in the spall area is demolished and recovered before blasting.

[0019] Furthermore, when the access road is filled, a filling pipe and an exhaust pipe are respectively set up on the top plate of the access road, and the height of the exhaust pipe is higher than the filling pipe; the filling is carried out in batches, and the filling height of each time does not exceed 1 / 3 to 1 / 4 of the access road height, and the upper layer is filled after the lower layer filling body solidifies.

[0020] Furthermore, when filling the access road, a cemented filling body is used for filling, and the 28-day uniaxial compressive strength of the cemented filling body is greater than or equal to 3~5MPa.

[0021] Furthermore, the filling retaining wall is composed of wooden columns, steel grids, geotextiles and diagonal braces. The wooden columns are erected at the designed positions of the filling retaining wall and tied to the anchor rods of the top and bottom plates. A layer of steel grid is laid and fixed between the wooden columns, and 1 to 2 layers of geotextiles are laid on the steel grids. The wooden columns, steel grids and geotextiles constitute the filling retaining wall body. The filling retaining wall body is supported and fixed by diagonal braces, and a drainage pipe is also provided at the lower part of the filling retaining wall.

[0022] Beneficial effects

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) The mining efficiency of the stope is high and the production capacity is large. After the road construction is completed, the free surface and compensation space for the side road mining blasting are reserved near the side of the original rock ore body. This allows the mining of the adjacent road to be carried out by the side caving method, which effectively reduces the difficulty of the mining blasting, shortens the number of drilling holes and the drilling time, greatly improves the mining efficiency, and increases the mining production capacity.

[0025] (2) It can effectively reduce the cost of mining. On the one hand, by improving the efficiency and production capacity of mining, the cost per ton of ore can be effectively reduced. On the other hand, the approach mining is optimized from tunneling blasting to lateral blasting, which reduces the blasting difficulty and the unit consumption of pyrotechnics, and can also reduce mining costs.

[0026] (3) By pre-setting pillars, the stability of the filling wall is improved, the exposed area of ​​the roof is reduced, and the stability of the approach roof is ensured while expanding the mining width. This increases the single filling area, reduces the number of fillings, and improves the filling efficiency. Since it is difficult to connect the roof during approach filling, several interval pillars are set on one side of the vein outside the tunnel to ensure the stability of the roof of the vein outside the tunnel.

[0027] (4) The present invention can improve the strength of the filling body. By reserving the pillars and installing a number of filling plate walls and drainage pipes between the pillars, water can be filtered simultaneously on multiple plate walls on both sides of the access road, achieving rapid and uniform water filtration of the filling slurry, accelerating the solidification time of the filling body, and ensuring the filling and top connection effect. The installation of the pillars changes the connection method of the steel bars between the two access roads, reduces the weak surface structure between the access filling bodies, and improves the overall strength of the filling body.

[0028] The technical solution of the present invention is further described in detail below through the accompanying drawings and specific implementation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1This is a schematic diagram of the first-layer mining route for the downward approach filling mining method with reserved interval pillars in an embodiment.

[0030] Figure 2 It is a schematic diagram of the slab mining of the first-layer mining approach of the downward approach filling mining method with reserved interval pillars in an embodiment.

[0031] Figure 3 This is a schematic diagram of the installation of filling retaining walls and filling pipes for the first-layer mining approach of a downward approach filling mining method with reserved interval pillars in an embodiment.

[0032] Figure 4 for Figure 3 A is an enlarged schematic diagram.

[0033] Figure 5 This is a schematic diagram of a filling retaining wall structure of a downward approach filling mining method with reserved interval pillars in an embodiment.

[0034] Figure 6 This is a schematic diagram of the mining on both sides of the first mining route of the layered approach in a downward approach filling mining method with reserved interval pillars in an embodiment.

[0035] Figure 7 This is a schematic diagram of sidewall mining and pillar recovery on both sides of a pre-spaced pillar downward approach filling mining method in an embodiment.

[0036] Numbers in the figure: 1—vein tunnel, 2—ore body, 3—first mining approach, 4—mine pillar, 5—slab mining area, 6—cemented backfill, 7—wooden column, 8—diagonal brace, 9—steel grid, 10—geotextile, 11—drainage pipe, 12—rebar, 13—rebar welding point, 14—filling pipe, 15—exhaust pipe, 16—approach. DETAILED DESCRIPTION

[0037] The following will clearly and completely describe the technical solutions of various embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0038] See also Figures 1-7 The figure shows a reserved interval pillar downward approach filling mining method which is a preferred solution of the present invention. The technical solution provided by the present invention includes the following steps:

[0039] Step 1: Divide the stope and arrange the mining and cutting engineering according to the method of downward approach filling mining. Mining is carried out in layers from top to bottom in the middle section. In the layer, the stope connecting road is constructed from the outside of the vein in a segmented level tunnel to the boundary of the ore body footwall. Then, from the stope connecting road, a vein tunnel 1 is constructed along the footwall of the ore body to the boundaries of both sides of the stope. The ore body in the layer is divided into approaches for mining. When mining in layers, the first mining approaches of the two adjacent layers are staggered by 1 / 2 of the approach width. The approach is 0.3% uphill from the footwall to the upper wall. The approach length is the thickness of the ore body. The cross-sectional specifications of the approach are determined according to the engineering geological conditions of the ore body rock and the magnitude of the ground stress.

[0040] Step 2: Mining is carried out from the center to the two wings within the mining area. At the center of the mining area, the first mining approach is constructed from the vein tunnel 1 perpendicular to the direction of the ore body to the upper wall boundary of the ore body. The first mining approach 3 is mined by excavation, and blasting is carried out with the face as the only free face and compensation space; then, interval spalling mining is carried out on both sides of the first mining approach 3 to form a blasting compensation space for subsequent approach mining. The width of the spalling mining is 1 / 2 of the approach width, the height of the spalling mining is the approach height, and the length of a single spalling mining area 5 is greater than or equal to 3 times the single-cycle advance of the approach; pillars 4 are left at intervals between the spalling mining areas 5 from the boundary of the vein tunnel 1. The width of the pillars 4 is 1 / 2 of the approach width, the length is not greater than the single-cycle advance of the approach, and the height is equal to the approach height. The top plates of the access road and the spall mining area 5 are supported by anchor cables + mesh. After the spall mining is completed, a steel bar 12 mesh is laid on the bottom plate of the access road. Both ends of each steel bar 12 in the width direction of the access road are folded upward at the access road wall and a length of not less than 1.5m is reserved. The reserved lengths of two adjacent steel bars 12 are staggered, with a length difference of 0.5m. The steel mesh is suspended from the anchor cables of the access roof using hanging rods. A backfill retaining wall is then erected at the outer boundary of the spalling area and at the access entrance. The backfill retaining wall consists of wooden columns 7, steel grid 9, geotextile 10, and diagonal braces 8. The wooden columns 7 are erected at the designed location of the backfill retaining wall and tied to the anchor rods of the top and bottom plates. A layer of steel grid 9 is laid and fixed between the wooden columns 7. One to two layers of geotextile 10 are laid on the steel grid 9. The wooden columns 7, steel grid 9, and geotextile 10 form the backfill retaining wall body, which is supported and fixed by diagonal braces 8. A drainage pipe 11 is also installed at the bottom of the backfill retaining wall. The access road is then filled and the roof is connected. When filling the access road, a filling pipe 14 and an exhaust pipe 15 are installed on the access road roof. The exhaust pipe 15 is higher than the filling pipe 14. Filling is carried out in stages, with each filling height not exceeding 1 / 3 to 1 / 4 of the access road height. The upper layer of filling is carried out after the lower layer of filling solidifies. The access road is filled with a cemented filling material 6, and the 28-day uniaxial compressive strength of the cemented filling material 6 is greater than or equal to 3 to 5 MPa.

[0041] Step 3: After the filling and maintenance of the first mining route 3 is completed, the two adjacent routes 16 are mined at the same time. First, the route is constructed from the vein tunnel 1 perpendicular to the direction of the ore body to the upper wall boundary of the ore body. When the route is mined, if there is a ore pillar 4 on the side of the filling body, mining is carried out by excavation. The face is the only free surface and compensation space for blasting. When the side of the filling body is the spall area of ​​the previous route, the spall area is used as the main free surface and compensation space for lateral blasting and mine collapse. At this time, the filling retaining wall on the side of the spall area on the side of the filling body is demolished and recovered before blasting. Then, intermittent spalling is carried out on the side of the approach close to the original rock to form a blasting compensation space for subsequent approach mining. The width of the spalling is 1 / 2 of the approach width, the height of the spalling is the approach height, and the length of a single spalling area 5 is greater than or equal to 3 times the single-cycle footage of the approach; pillars 4 are left at intervals between the spalling areas 5 from the boundary of the vein tunnel 1, and the width of the pillars 4 is 1 / 2 of the approach width, the length is not greater than the single-cycle footage of the approach, and the height is equal to the approach height. The top plate of the access road and the spalling mining area 5 is supported by anchor cables + mesh. After the spalling mining is completed, the ore pillars 4 on the side of the filling body are recovered in sequence from the upper wall to the lower wall of the ore body. In order to ensure the stability of the intersection of the access road and the vein tunnel 1, the ore pillars 4 at the boundary of the vein tunnel 1 are not recovered. Then a steel bar 12 mesh is laid on the bottom plate of the access road. Each steel bar 12 in the width direction of the access road is folded upward at the access road wall on the side close to the original rock and a length of not less than 1.5m is reserved. The reserved lengths of two adjacent steel bars 12 are staggered, with a length difference of 0.5m. At the same time, the steel bars 12 reserved for the steel mesh laid on the previous access road close to the filling body are welded to the steel mesh laid this time, and the steel bar welding points 13 are staggered. The steel mesh is hung on the anchor cable of the access roof by using hanging rods, and a filling retaining wall is erected at the outer boundary of the slab area and the access entrance. The filling retaining wall is composed of wooden columns 7, steel grids 9, geotextiles 10 and diagonal braces 8. The wooden columns 7 are erected at the designed position of the filling retaining wall and tied to the anchor rods of the top and bottom plates. A layer of steel grids 9 is laid and fixed between the wooden columns 7, and 1 to 2 layers of geotextiles 10 are laid on the steel grids 9. The wooden columns 7, steel grids 9 and geotextiles 10 constitute the filling retaining wall body, and the filling retaining wall body is supported and fixed by diagonal braces 8. A drainage pipe 11 is also provided at the lower part of the filling retaining wall. The access road is then filled and topped off. During the filling process, a filling pipe 14 and an exhaust pipe 15 are installed on the access road roof. The exhaust pipe 15 is higher than the filling pipe 14. Filling is done in stages, with each filling height not exceeding 1 / 3 to 1 / 4 of the access road height. The upper layer is filled only after the lower layer of filling solidifies. The access road is filled with a cemented filler 6, which has a 28-day uniaxial compressive strength of greater than or equal to 3 to 5 MPa.

[0042] Step 4: After the filling and curing of the access road mined in step 3 is completed, the two access roads on one side of the filled access road are mined again. The mining and filling methods are the same as those in step 3. This cycle is repeated until the mining of the entire first layer is completed.

[0043] Step 5. After the first layer is mined, the next layer is mined. The layer mining and filling method is the same as steps 2 to 4. This cycle is repeated until the mining of the entire stope is completed. At this time, the steel mesh laid on the bottom plate of each layer access road is hung on the steel mesh of the previous layer through the hanger.

[0044] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A method of filling mining with a downward approach using reserved interval pillars, characterized in that: The following steps are involved: Step 1: Divide the stope and arrange the mining and cutting works according to the downward approach and filling mining method. Mining is carried out in layers from top to bottom in the middle section. Within the layers, a stope connecting road is constructed from the outside of the vein in a segmented level road to the boundary of the ore body footwall. Then, a vein road is constructed from the stope connecting road in the footwall of the ore body to the boundaries of both sides of the stope. The ore body within the layers is divided into approaches for mining. Step 2: Mining is carried out from the center to the two wings within the stope layer. At the center of the stope layer, the first mining approach is constructed from the vein lane perpendicular to the ore body strike direction to the boundary of the ore body hanging wall. Then, interval spalling is carried out on both sides of the first mining approach to form blasting compensation space for subsequent approach mining. Pillars are left at intervals between the spalling mining areas from the boundary of the vein lane. The roof of the approach and spalling mining area is supported by anchor cables + mesh. After the spalling mining is completed, a steel mesh is laid on the bottom plate of the approach. The steel mesh is hung on the anchor cables of the approach roof with hangers. Then, filling retaining walls are erected at the outer boundary of the spalling area and the approach entrance, and the approach is filled and connected to the roof. Step 3: After the filling and maintenance of the first mining route is completed, the two adjacent routes are mined at the same time. First, the route is constructed from the vein lane perpendicular to the ore body strike direction to the boundary of the upper wall of the ore body, and then the interval-type spalling mining is carried out on the side of the route close to the original rock to form a blasting compensation space for the subsequent route mining. Pillars are left at intervals between the spalling mining areas from the boundary of the vein lane. The roof of the route and the spalling mining area is supported by anchor cables + mesh. After the spalling mining is completed, the pillars on the side of the filling body are successively recovered from the upper wall of the ore body to the lower wall. In order to ensure the stability of the intersection of the route opening and the vein lane, the pillars at the boundary of the vein lane are not recovered. Then, a steel mesh is laid on the bottom plate of the route, and the steel mesh is hung on the anchor cables of the route roof with hangers. Filling retaining walls are erected at the outer boundary of the spalling area and the route opening, and the route is filled and topped. Step 4: After the filling and curing of the access road mined in step 3 is completed, the two access roads on one side of the filled access road are mined again. The mining and filling methods are the same as those in step 3. This cycle is repeated until the mining of the entire first layer is completed. Step 5: After the first layer is mined, the next layer is mined. The layer mining and filling methods are the same as steps 2 to 4. This cycle is repeated until the entire stope is mined. At this time, the steel mesh laid on the bottom plate of each layer access road is hung on the steel mesh of the previous layer through the hanger rod; When laying the steel mesh, both ends of each steel bar in the width direction of the first approach in the layer are folded upwards at the approach wall and a length of not less than 1.5m is reserved, and the reserved lengths of two adjacent steel bars are staggered, with a length difference of 0.5m; when laying steel mesh in other approaches within the layer, each steel bar in the width direction of the approach is folded upwards at the approach wall on the side of the original rock and a length of not less than 1.5m is reserved, and the reserved lengths of two adjacent steel bars are staggered, with a length difference of 0.5m. At the same time, the reserved steel bars of the steel mesh laid in the previous approach close to the filling body are welded to the steel mesh laid this time, and the welding points are staggered.

2. The method of mining with a downward approach and filling with reserved interval pillars according to claim 1 is characterized in that: During the layered mining, the first mining routes of the two upper and lower adjacent layers are staggered by 1 / 2 of the route width.

3. The method of mining with a downward approach and filling with reserved interval pillars according to claim 1 is characterized in that: The access road slopes up 0.3% from the lower wall to the upper wall, the length of the access road is the thickness of the ore body, and the cross-sectional specifications of the access road are determined according to the engineering geological conditions of the ore body rock and the magnitude of the ground stress.

4. The method of mining with a downward approach and filling with reserved interval pillars according to claim 1 is characterized in that: The width of the spall mining is 1 / 2 of the width of the approach, the height of the spall mining is the height of the approach, and the length of a single spall mining area is greater than or equal to 3 times the single-cycle footage of the approach; the width of the pillar is 1 / 2 of the width of the approach, the length is not greater than the single-cycle footage of the approach, and the height is equal to the height of the approach.

5. The method of mining with downward filling of reserved interval pillars according to claim 1 is characterized in that: During stratified mining, the first mining approach adopts the tunneling method for mining, and the face is the only free face and compensation space for blasting; when the other approaches are mining, when the side of the filling body is the pillar, the tunneling method is adopted for mining, and the face is the only free face and compensation space for blasting. When the side of the filling body is the spall area of ​​the previous approach mining, the spall area is used as the main free face and compensation space for lateral blasting and collapse of the mine. At this time, the filling retaining wall on the side of the filling body in the spall area is demolished and recovered before blasting.

6. The method of mining with downward filling of reserved interval pillars according to claim 1 is characterized in that: When the access road is filled, a filling pipe and an exhaust pipe are respectively set up on the access road top plate, and the height of the exhaust pipe is higher than the filling pipe; the filling is carried out in batches, and the filling height of each time does not exceed 1 / 3 to 1 / 4 of the access road height. The upper layer filling is carried out after the lower layer filling body solidifies.

7. The method of mining with downward filling of reserved interval pillars according to claim 1 is characterized in that: When the access road is filled, a cemented filling body is used for filling, and the 28-day uniaxial compressive strength of the cemented filling body is greater than or equal to 3 to 5 MPa.

8. The method of mining with downward entry and filling with reserved interval pillars according to claim 1 is characterized in that: The filling retaining wall is composed of wooden columns, steel grids, geotextiles and diagonal braces. The wooden columns are erected at the designed positions of the filling retaining wall and tied to the anchor rods of the top and bottom plates. A layer of steel grid is laid and fixed between the wooden columns, and 1 to 2 layers of geotextiles are laid on the steel grids. The wooden columns, steel grids and geotextiles constitute the filling retaining wall body. The filling retaining wall body is supported and fixed by diagonal braces. A drainage pipe is also provided at the lower part of the filling retaining wall.

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