Safe mining method for water-rich gently-inclined coal seam

Abstract

The invention discloses a safe mining method for a water-rich gently-inclined coal seam. The safe mining method comprises the steps of open-off cut strip preparation, local drainage system construction, open-off cut strip mining, raw coal transverse mining, continuous drainage system construction, earth retaining dam construction, inner drainage follow-up, mining circulation and the like. The coal bodies and the rolling earth retaining dams are adopted to alternately support the inner refuse dump, and the stability of the slope of the inner refuse dump is guaranteed; long-term three-side precipitation of the coal body, especially bedding precipitation in the advancing direction, is beneficial to precipitation and quality improvement of raw coal; the coal seam is mined from the middle to the two sides in the variable propelling direction in a concentrated mode, the inner discharge distance of stripped objects along the end slopes on the two sides is shortened, and meanwhile the inner discharge distance of stripped objects in the middle is shortened through the soil discharging bridge extending rapidly; the overall advancing direction and step division of the strip mine are not changed, the construction technology is simple, used equipment is original mine equipment, and the cost is controllable.

Description

Technical Field

[0001] The invention relates to a coal seam mining method, in particular to a safe mining method for a water-rich gently inclined coal seam. Background Art

[0002] ‌When open-pit mining is adopted, the gently inclined coal seam refers to the coal seam with a floor inclination angle of 5°~15°. The following problems are faced during the mining process. First, the inclination angle is large. Although certain internal drainage conditions are met, the dump still has a tendency to slide down along the floor, which seriously affects the safety and effective capacity of the internal dump slope. Second, water from the end wall and the internal dump will gather in the mining face and soak the coal mining face for a long time. For open-pit mines with large water inflow, it will not only affect the safe operation of equipment in the mining process, but also increase the moisture content of the mined raw coal, affecting the calorific value of the raw coal. Summary of the invention

[0003] In view of the problems existing in the above-mentioned prior art, the present invention provides a method for safe mining of water-rich gently inclined coal seams, which ensures the safety of the slope of the inner dump and reduces the moisture content of the raw coal.

[0004] To achieve the above object, the present invention provides the following technical solution: a method for safe mining of water-rich gently inclined coal seams, comprising the following steps: Preparation of eye-cutting strips: On the working coal seam, at the positions on both sides of the central axis of the coal seam, eye-cutting strips are divided along the direction of open-pit mine advancement. The width of the eye-cutting strips in the direction of open-pit mine advancement is less than the annual advancement rate. The stripping steps above the roof of the eye-cutting strip coal seam are advanced in advance to completely expose the coal seam in the eye-cutting strips. Construct a local drainage system: At the junction of the coal seam in the cut-eye strip and the upper stripping step, dig a trench on the floor of the ultra-deep coal seam as a drainage ditch; the drainage ditch is arranged with the central axis of the coal seam as the midpoint, and is arranged along the floor of the coal seam to the two side walls in a pseudo-inclined manner, forming a water flow slope of 0.5%~1%. The position close to the two side walls is the low point, and water collection pits connected to the drainage ditch are dug at the low point; at the central axis of the coal seam, dig a trench on the floor of the ultra-deep coal seam along the advancement direction of the open-pit mine as a water diversion ditch, and the water diversion ditch is connected with the drainage ditch to form a "T"-shaped drainage structure; Cut-eye strip mining: The coal seams in the cut-eye strips are divided into small steps for mining along the direction of the open-pit mine advancement; after the coal seam is mined, the floor is exposed, and the width of the exposed range along the coal seam strike is more than four times the thickness of the coal seam. Then, rough stones are laid in the area of ​​the super-deep coal seam floor of the drainage ditch and the water diversion ditch, and covered with straw mats or gauze to form a drainage blind ditch and a water diversion blind ditch; Horizontal mining of raw coal: After the cutting strip is completed, the steps on both sides of the cutting strip are widened to form two horizontal mining working faces. The horizontal mining working faces are advanced towards the end wall direction to mine the working wall coal seam. The stripping steps on the upper part of the coal seam are advanced ahead of the horizontal mining working face. Build a continuous drainage system: As the horizontal mining work surface continues to advance towards the two sides of the end wall, the coal seam floor is constantly exposed, the precipitation blind ditch also extends to both sides synchronously, and the water collection pit also changes its construction position synchronously, but it is always located at the end point of the precipitation blind ditch close to the end wall; on the coal seam floor, a phased water diversion blind ditch parallel to the water diversion blind ditch is built every 100~200m, and connected with the precipitation blind ditch; Construction of retaining dam: During the horizontal mining of raw coal, in the goaf after the mining of the cut-eye strip coal seam, the stripped materials from the open-pit mine are discarded and crushed in layers along the edge of the drainage ditch close to the inner dumping area to form a retaining dam; at the same time, permeable materials are backfilled between the working coal seam and the retaining dam as a permeable layer; Internal dumping follow-up: After the retaining dam reaches the designed height and the retaining dam extends to the side walls on both sides beyond the width of two open-pit mine lanes, a dumping bridge connecting the internal dumping yard and the working side coal seam is built above the retaining dam with the coal seam centerline as the starting point. Starting from the dumping bridge, the internal dumping yard follows up the dumping of soil in the direction of the side walls and the open-pit mine respectively; Mining cycle: When the raw coal reaches the end walls on both sides and the inner spoil dump follows up to the end walls simultaneously, this round of mining ends. At this time, the permeable layer is recovered, and then the next round of cutting strips are delineated, and the next round of mining is carried out according to the above steps, and so on, in a cycle.

[0005] Furthermore, the length of the cut-eye strip in the direction perpendicular to the open-pit mine advancement direction is not less than L , L =2 B min + H arctan β ,in: B min is the minimum pit bottom width, H is the coal seam height, β It is the slope angle of the coal seam, and the vertical depth is less than the height of one step.

[0006] Furthermore, the drainage ditch is more than 2m deep into the coal seam floor.

[0007] Furthermore, the water diversion ditch is more than 2m deep into the coal seam floor.

[0008] Furthermore, in the eye-cutting strip mining step, small steps are divided into horizontal layers from the working side to the inner spoil dump, and the height of each step does not exceed 3m.

[0009] Furthermore, the retaining dam takes the central axis of the coal seam as the starting point, maintains a minimum pit bottom width distance from the horizontal mining working face and follows the advancement. The total height of the retaining dam is equal to the depth reduction of the open-pit mine at one time, and the layer height is 1~2m.

[0010] Furthermore, in the inner dump follow-up step, as the inner dump advances toward the end walls on both sides, a second dump bridge connecting the inner dump and the upper steps of the working side coal seam is built near the central axis of the coal seam.

[0011] Compared with the prior art, the coal body and the rolled retaining dam in the present invention alternately support the inner dumping yard to ensure the stability of the slope of the inner dumping yard; the coal body is dewatered on three sides for a long time, especially the dewatering along the layer in the advancing direction, which is beneficial to the dewatering and quality improvement of the raw coal; the coal seam is concentratedly mined by changing the advancing direction from the middle to both sides, which shortens the transportation distance of the stripping materials along the inner discharge of the two side end walls, and the rapidly extending dumping bridge shortens the inner discharge distance of the stripping materials in the middle part; the present invention does not change the overall advancing direction of the open-pit mine, the construction process is simple, the equipment used are all the original equipment of the mine, and the cost is controllable. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 A schematic diagram of the eye-cutting strip preparation and local drainage system of the present invention; Figure 2 It is a schematic diagram of the local drainage system and the cutting strip mining of the present invention; Figure 3 This is a schematic diagram of the horizontal mining of raw coal and the construction of a continuous drainage system according to the present invention; Figure 4 It is a schematic diagram of the construction of the retaining dam of the present invention; Figure 5 It is a schematic diagram of the inner row follow-up of the present invention; In the figure: 1-working coal seam; 2-open pit mine advancement direction; 3-cutting strip; 4-coal seam centerline; 5-peeling step; 6-drainage ditch; 7-end wall; 8-collection pit; 9-water diversion ditch; 10-drainage blind ditch; 11-water diversion blind ditch; 12-horizontal mining working face; 13-stage water diversion blind ditch; 14-inner dump; 15-retaining dam; 16-permeable layer; 17-drainage bridge. DETAILED DESCRIPTION

[0013] The present invention will be further described below in conjunction with the accompanying drawings.

[0014] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0015] like Figures 1 to 5 As shown, the present invention provides a technical solution, including the steps of preparing the cut-eye strip, building a local drainage system, mining the cut-eye strip, horizontal mining of raw coal, building a continuous drainage system, building a retaining dam, following up the internal drainage, and mining cycle.

[0016] Cut Eye Strip Preparation: According to the height of the open-pit mine step and the horizontal advancement intensity, a cutting strip 3 is divided along the open-pit mine advancement direction 2 at the position symmetrically located on both sides of the coal seam center axis 4 on the working coal seam 1. The width of the cutting strip 3 in the open-pit mine advancement direction 2 is less than the annual advancement rate, and the length in the direction perpendicular to the open-pit mine advancement direction 2 is not less than L , L =2 B min + H arctan β ,in: B min The minimum pit bottom width is generally not less than 50m. H is the coal seam height, β is the slope angle of the coal seam; the vertical depth reduction is less than the height of a step, and the vertical depth reduction is the height difference between the starting and ending points of the cutting strip 3 corresponding to the coal seams.

[0017] The stripping step 5 above the roof of the coal seam in the cutting strip 3 is advanced in advance to completely expose the coal seam in the cutting strip 3; the steps above the roof of the coal seam adopt a combined step + steep working wall mining mode to reduce the amount of advanced stripping engineering.

[0018] Construction of local drainage system: At the junction of the coal seam in the cut-eye strip 3 and the upper stripping step 5, a trench more than 2m deep in the bottom plate of the ultra-deep coal seam is dug with a long-arm excavator as a drainage ditch 6; the drainage ditch 6 takes the central axis 4 of the coal seam as the midpoint, and is arranged pseudo-inclined along the bottom plate of the coal seam toward the end walls 7 on both sides, forming a water flow slope of 0.5% to 1%. The drainage ditch 6 as a whole has a high middle and low two end structures. The position of the drainage ditch 6 close to the end walls 7 on both sides is the low point, and a collection pit 8 connected to the drainage ditch 6 is dug at this low point.

[0019] At the center axis 4 of the coal seam, a trench more than 2m deep from the bottom of the ultra-deep coal seam is dug along the open-pit mine advancement direction 2 as a water diversion ditch 9. The water diversion ditch 9 is connected with the drainage ditch 6 to form a "T"-shaped drainage structure, which collects the pit bottom water into the sump 8 at both ends of the drainage ditch 6 for discharge.

[0020] Cut-eye strip mining: The coal seam in the cutting strip 3 is divided into small steps for mining along the open-pit mine advancement direction 2. A hydraulic backhoe is used for digging and loading. The principle of small step division is horizontal stratification from the working side to the inner spoil dump 14. The height of each step does not exceed 3m to adapt to the change of coal seam inclination to the greatest extent.

[0021] After coal seam mining, the bottom plate is exposed. When the width of the exposed range along the coal seam direction is more than four times the thickness of the coal seam, rubble is laid in the area of ​​the super-deep coal seam bottom plate of the drainage ditch 6 and the water diversion ditch 9, and covered with straw mats or gauze to form a drainage blind ditch 10 and a water diversion blind ditch 11, which can continuously play the role of coal seam drainage and precipitation.

[0022] Horizontal mining of raw coal: After the cutting strip 3 is completed, the steps on both sides of the cutting strip 3 in the advancing direction are widened to form two horizontal mining working faces 12. The horizontal mining working faces 12 are respectively advanced toward the end wall 7 to mine the working wall coal seam 1. The stripping step 5 on the upper part of the coal seam is advanced ahead of the horizontal mining working face 12 to accelerate the recovery of raw coal.

[0023] Building a continuous drainage system: As the horizontal mining face 12 is continuously advanced toward the end walls 7 on both sides, the coal seam floor is continuously exposed, the precipitation blind ditch 10 is also synchronously extended to both sides, and the sump 8 is also synchronously changed in construction position, but is always located at the end position of the precipitation blind ditch 10 close to the end wall 7; on the coal seam floor, a phased water diversion blind ditch 13 parallel to the water diversion blind ditch 10 is constructed at intervals of 100 to 200 meters, and is connected to the precipitation blind ditch 10, so as to divert the water from the inner spoil dump 14 to the precipitation blind ditch 10 and collect it in the sump 8.

[0024] Construction of retaining dams: During the horizontal mining of raw coal, in the goaf after the mining of the coal seam in the eye-cutting strip 3, the open-pit mine stripping materials are discharged in layers and crushed along the edge of the drainage ditch 6 close to the inner spoil dump 14 to form a retaining dam 15 supporting the inner spoil dump 14. The retaining dam 15 takes the central axis 4 of the coal seam as the starting point and follows the advancement while maintaining the minimum pit bottom width distance from the horizontal mining working face 12. The total height of the retaining dam 15 is equal to the depth reduction of the open-pit mine at one time, and the layer height is 1~2m. The specific height is determined according to the effective compaction depth of the rolling equipment.

[0025] At the same time, permeable materials such as gravel are backfilled between the working coal seam 1 and the retaining dam 15 as a permeable layer 16, which can not only support the retaining dam 15, but also ensure that the slope of the working coal seam 1 can seep normally to the precipitation blind ditch 10.

[0026] Internal follow-up: After the retaining dam 15 reaches the designed height and extends toward the two side end walls 7 to a width exceeding two open-pit mine driveways, a discharge bridge 17 connecting the inner discharge yard 14 and the working side coal seam 1 is built above the retaining dam 15 with the coal seam centerline 4 as the starting point. With the discharge bridge 17 as the starting point, the inner discharge yard 14 follows up with discharge in two directions, namely, toward the two side end walls 7 and the open-pit mine advancement direction 2.

[0027] In order to accelerate the internal dumping, as the internal dumping yard 14 advances toward the end walls 7 on both sides, a second dumping bridge 17 connecting the internal dumping yard 14 and the upper steps of the working side coal seam 1 is built near the central axis 4 of the coal seam.

[0028] Mining cycle: When the raw coal reaches the end walls 7 on both sides and the inner spoil dump 14 follows up to the end walls 7 synchronously, this round of mining is ended. At this time, the permeable layer 16 is recovered, and then the next round of cutting strips 3 are delineated, and the next round of mining is carried out according to the above steps, and so on, for cyclic mining.

[0029] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0030] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any slight modification, equivalent substitution and improvement made to the above embodiment based on the technical essence of the present invention should be included in the protection scope of the technical solution of the present invention.

Claims

1. A safe mining method for water-rich gently inclined coal seams, characterized in that: The following steps are involved: Cut Eye Strip Preparation: At positions on both sides of the coal seam center axis (4) on the working coal seam (1), cut-eye strips (3) are divided along the open-pit mine advancement direction (2), and the width of the cut-eye strips (3) in the open-pit mine advancement direction (2) is less than the annual advancement rate; the stripping step (5) above the coal seam roof of the cut-eye strips (3) is advanced ahead to completely expose the coal seam in the cut-eye strips (3); Construction of local drainage system: At the junction of the coal seam in the cut-eye strip (3) and the upper stripping step (5), a groove is dug in the floor of the ultra-deep coal seam as a drainage ditch (6); the drainage ditch (6) is arranged with the coal seam center axis (4) as the midpoint, and is arranged along the coal seam floor toward the two side end walls (7) respectively, forming a water flow slope of 0.5% to 1%, and the position close to the two side end walls (7) is the low point, and a water collection pit (8) connected to the drainage ditch (6) is dug at the low point; at the position of the coal seam center axis (4), a groove is dug in the floor of the ultra-deep coal seam along the open-pit mine advancement direction (2) as a water guide ditch (9), and the water guide ditch (9) is connected with the drainage ditch (6) to form a "T"-shaped drainage structure; Cut-eye strip mining: The coal seam in the cut-eye strip (3) is divided into small steps for mining along the open-pit mine advancement direction (2); after the coal seam is mined, the floor is exposed, and after the width of the exposed range along the coal seam strike is more than four times the thickness of the coal seam, rough stones are laid in the area of ​​the floor of the super-deep coal seam of the drainage ditch (6) and the water diversion ditch (9), and covered with straw mats or gauze to form a drainage blind ditch (10) and a water diversion blind ditch (11); Horizontal mining of raw coal: After the cutting strip (3) is completed, the steps on both sides of the cutting strip (3) are widened in the advancing direction to form two horizontal mining working faces (12). The horizontal mining working faces (12) are respectively advanced toward the end wall (7) to mine the working wall coal seam (1). The stripping step (5) on the upper part of the coal seam is advanced ahead of the horizontal mining working face (12); Building a continuous drainage system: As the horizontal mining working face (12) continues to advance toward the two side walls (7), the coal seam floor is continuously exposed, the drainage blind ditch (10) also extends to both sides synchronously, and the water collection pit (8) also changes its construction position synchronously, but is always located at the end point of the drainage blind ditch (10) close to the side wall (7); a staged water diversion blind ditch (13) parallel to the water diversion blind ditch (10) is constructed on the coal seam floor at intervals of 100 to 200 meters, and is connected to the drainage blind ditch (10); Construction of retaining dams: During the horizontal mining of raw coal, in the goaf after the mining of the coal seam in the cut-eye strip (3), the stripped materials of the open-pit mine are discharged and crushed in layers along the edge of the drainage ditch (6) close to the inner dump (14) to form a retaining dam (15); at the same time, permeable materials are backfilled between the working coal seam (1) and the retaining dam (15) as a permeable layer (16); Internal follow-up: After the retaining dam (15) reaches the designed height and the retaining dam (15) extends in the direction of the two side walls (7) beyond the width of two open pit mine tracks, a dumping bridge (17) is constructed above the retaining dam (15) with the coal seam centerline (4) as the starting point, connecting the inner dumping yard (14) and the working side coal seam (1). With the dumping bridge (17) as the starting point, the inner dumping yard (14) follows up with the dumping in the direction of the two side walls (7) and the open pit mine advancement direction (2); Mining cycle: When the raw coal reaches the two side end walls (7) and the internal spoil dump (14) follows up to the end walls (7) synchronously, this round of mining ends. At this time, the permeable layer (16) is recovered, and then the next round of cutting strips (3) are delineated, and the next round of mining is carried out according to the above steps, and so on, in a cycle of mining.

2. A method for safe mining of water-rich gently inclined coal seams according to claim 1, characterized in that: The length of the cut-eye strip (3) perpendicular to the open-pit mine advancement direction (2) is not less than L , L =2 B min + H arctan β ,in: B min is the minimum pit bottom width, H is the coal seam height, β It is the slope angle of the coal seam, and the vertical depth is less than the height of one step.

3. A method for safe mining of water-rich gently inclined coal seams according to claim 1, characterized in that: The drainage ditch (6) is more than 2 m deep in the coal seam floor.

4. A method for safe mining of water-rich gently inclined coal seams according to claim 1, characterized in that: The water guide ditch (9) is more than 2 m deep in the coal seam floor.

5. A safe mining method for water-rich gently inclined coal seams according to claim 1, characterized in that: In the eye-cutting strip mining step, small steps are divided into horizontal layers from the working side to the inner spoil dump (14), and the height of each step does not exceed 3m.

6. A method for safe mining of water-rich gently inclined coal seams according to claim 1, characterized in that: The retaining dam (15) starts from the coal seam centerline (4) and follows the horizontal mining working face (12) while maintaining a minimum pit bottom width distance. The total height of the retaining dam (15) is equal to the depth reduction of the open-pit mine, and the layer height is 1-2 m.

7. A method for safe mining of water-rich gently inclined coal seams according to claim 1, characterized in that: In the inner dump follow-up step, as the inner dump (14) advances toward the two side end walls (7), a second dump bridge (17) is constructed near the coal seam centerline (4) to connect the inner dump (14) and the upper steps of the working side coal seam (1).

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