Method for controlling thick and hard low-position rock stratum under high-strength mining

Abstract

The invention relates to the technical field of coal mining, in particular to a control method for a thick and hard low-position rock stratum under high-strength mining, which comprises the following steps of: arranging a working surface along the trend and reserving a section coal pillar; the coal seam is divided into a lower fully-mechanized coal mining layer and an upper caving layer in height, an air return gate road and a transportation gate road of the first working face are excavated in the lower fully-mechanized coal mining layer, and open-off cut communication is conducted; the cut is arranged on the inclined lower portion, and coal caving chambers are arranged on the inclined lower portion of the cut at intervals of cut coal pillars. Fully-mechanized coal mining layering is stoped by adopting a full caving method; a coal caving funnel is constructed in the open-off cut coal pillar, and upper caving ore is caved into a coal caving chamber; intervention roof caving is conducted on a thick and hard direct roof at the position where a goaf is formed through coal caving; in the trend, the top cutting position is inwards staggered by a certain distance from the stoping boundary of the first working face; and the top-cutting staggered layer space is filled with a filling material. A caving mine formed by caving of upper-layer coal plays a role of a caving zone to support a low-position roof rock stratum, and strong mine pressure is prevented from being formed to endanger safety; the method can greatly improve the recovery rate.

Description

Technical Field

[0001] The present invention relates to the technical field of coal mining, and in particular to a method for controlling thick, hard, and low-lying rock strata under high-intensity mining. Background Art

[0002] Thick and hard rock strata restrict the safe mining of coal mines. Due to their great thickness and strength, thick and hard rock strata will only break after being exposed in a large area after coal seam mining. That is, their pressure step distance is large and the pressure is strong, which seriously affects the safe mining of coal seams. When the thick and hard rock strata are located at a low position, that is, close to the coal seam, for example, when the direct roof is a thick and hard rock strata, the direct roof will not collapse after coal seam mining, and no falling rock blocks can be formed to fill the goaf, thereby failing to provide a buffer for the collapse of the roof rock strata and failing to reduce the collapse height of the roof rock strata, resulting in the low-lying thick and hard rock strata collapsing directly onto the bottom plate, causing a more intense impact and making coal seam mining more dangerous. If high-intensity mining is carried out under thick coal seams, the impact will be even stronger, and the risk of coal seam mining will be further increased. Therefore, how to safely mine thick coal seams under thick and hard low-lying rock strata has become a major technical challenge in this field. Summary of the Invention

[0003] The present invention proposes a method for controlling thick, hard, low-lying rock formations under high-intensity mining, which can partially solve the technical problems described in the background art above. For example, the method of the present invention is particularly suitable for situations where the immediate roof is a thick, hard, low-lying rock formation, the coal seam thickness is large but less than 20% of the thick, hard immediate roof, and the coal seam is a medium-sloping coal seam, comprising the following steps:

[0004] S1: Arrange several working faces along the coal seam, leaving segmented coal pillars between adjacent working faces; divide the coal seam into a lower fully-mechanized mining layer and an upper collapsed layer in terms of height; excavate a return air chute and a transport chute from the first working face in the lower fully-mechanized mining layer and open a cut to connect them; the cut is arranged at the lower part of the first working face, and coal chambers are arranged at intervals between the cut coal pillars in the lower part of the cut;

[0005] S2: Use the full caving method to mine the lower fully mechanized mining layer of the first working face;

[0006] S3: Construct a coal caving funnel in the cut coal pillar and discharge the upper caving ore into the coal caving chamber; in the process of discharging the upper caving ore, intervene with the thick and hard low-lying rock layer in the void area; in the strike direction, the top cutting position is staggered inward a certain distance from the mining boundary of the first working face; in the dip direction, the top cutting is carried out at a set interval starting from the withdrawal line;

[0007] S4: Filling the top-cut staggered space adjacent to the second working surface with filling materials;

[0008] S5: Mining the second working face with reference to steps S1-S4.

[0009] Preferably, in step S1, the heights of the lower fully-mechanized mining layer and the upper collapsed layer should satisfy the following requirements: after the lower fully-mechanized mining layer is mined, the upper collapsed layer collapses into block coal, and the increased volume of the upper collapsed layer is equal to or slightly smaller than the volume of the lower fully-mechanized mining layer.

[0010] Preferably, in step S2, the coal mining machine is used in conjunction with the hydraulic support to adopt the full caving method to mine the lower fully mechanized mining layer, and the hydraulic support adopts the hydraulic support used for mining the full height at one time.

[0011] Preferably, in step S5, while mining is being carried out on the first working face, excavation work is simultaneously carried out on the transport chute and the cut eye of the second working face. After mining is completed on the first working face, excavation work is carried out on the return air chute of the second working face and connected to the cut eye.

[0012] Invention points and beneficial effects: 1. Aiming at the high-intensity mining conditions of low-lying thick hard roof and thick coal seams, the present invention improves the non-coal ore mining process and applies it to coal seam mining. It proposes a stratified mining method of first mining the lower layer by the full caving method and then mining the upper layer. By utilizing the inclination of the coal seam and the stability of the low-lying thick hard roof, a coal caving chamber is established to completely separate caving from mining. Compared with traditional top coal caving mining, it can adapt to high-intensity mining needs and greatly improve the recovery rate (the coal recovery rate of top coal caving mining is only about 50%).

[0013] The coal mining efficiency can be greatly improved by using a coal mining machine to mine the lower layer and allowing the upper layer to collapse and break the coal by itself.

[0014] 2. This invention addresses the problem of no rock collapse to form a collapsed zone to support the roof during coal mining under low-lying, thick, and hard roof conditions. It proposes dividing the coal seam into two layers, the upper layer of coal collapse, which acts as a collapsed zone to support the lower roof rock layer, preventing it from collapsing and causing high pressure and endangering safety. Later, the upper collapsed coal seam is released all at once, and combined with pre-cracking of the lower roof rock layer, this can prevent it from collapsing and causing high pressure and endangering safety.

[0015] 3. The present invention staggers inwards by a certain distance when cutting the roof upwards. On the one hand, it facilitates the low-lying thick and hard roof to fall into the goaf. On the other hand, it can form a staggered space in the cut roof as a working space and pedestrian space for workers when placing coal. In addition, after the staggered space in the cut roof is filled with a filling body, the width of the section coal pillar can be reduced, which can further improve the overall coal seam recovery rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] When considered in conjunction with the accompanying drawings, the present invention can be more completely and better understood and many of the accompanying beneficial effects can be easily known by referring to the following detailed description. However, the drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. Among them:

[0017] Figure 1 —Three views of the construction status of step S1 of the present invention;

[0018] Figure 2 - Three views of the construction status of step S2 of the present invention;

[0019] Figure 3 - Three views of the construction status in step S3 of the present invention;

[0020] Figure 4 —Three views of the construction status of steps S4-S5 of the present invention;

[0021] Explanation of the accompanying numbers: 10-coal seam, 11-first working face, 12-second working face, 13-cutting eye, 14-cutting eye coal pillar, 15-coal discharge chamber, 16-coal discharge funnel, 17-return air chute, 18-transport chute, 19-section coal pillar, 101-lower comprehensive mining layer, 102-upper collapsed layer, 103-upper collapsed ore, collection line 104; 20-thick and hard low-lying rock layer / thick and hard direct roof, 21-inclined cutting top line (the dotted line represents the expected cutting top position, and the solid line represents the cutting top), 22-strike cutting top line, 23-cutting top collapsed block, 24-cutting top staggered layer space, 25-filling body; 31-overlying rock stratum collapsed body. DETAILED DESCRIPTION

[0022] The specific embodiments of the present invention are described below with reference to the accompanying drawings.

[0023] like Figure 1-4 As shown, the present invention proposes a method for controlling thick and hard low-level rock formations under high-intensity mining, which is particularly suitable for the case where the immediate roof is a thick and hard low-level rock formation (thick and hard immediate roof 20), the thickness of the coal seam 10 is large but less than the thickness of the thick and hard immediate roof 20, and the coal seam 10 is a medium-sloping coal seam, including the following steps:

[0024] S1: If Figure 1 As shown, several working faces are arranged in sequence along the direction of the coal seam, and segmented coal pillars 19 are left between adjacent working faces. Figure 1Two working faces are schematically shown, including a first working face 11 and a second working face 12. The coal seam 10 is mined in two layers in height, including a lower fully-mechanized mining layer 101 and an upper collapsed layer 102. A return air chute 17 and a transport chute 18 of the first working face 11 are excavated in the lower fully-mechanized mining layer 101, and a cut 13 is opened to connect the return air chute 17 and the transport chute 18. The cut 13 is arranged at the lower portion of the first working face 11, and a coal chamber 15 is arranged at the lower portion of the cut 13, separated by a cut coal pillar 14.

[0025] The heights of the lower fully-mechanized mining layer 101 and the upper collapsed layer 102 should satisfy the following requirements: after the lower fully-mechanized mining layer 101 is mined, the remaining upper collapsed layer 102 collapses into block coal (upper collapsed ore 103) with crushing and expansion properties, and the volume increased by the crushing and expansion of the upper collapsed layer 102 is substantially equal to or slightly smaller than the volume of the lower fully-mechanized mining layer 101, so that the block coal collapsed by the upper collapsed layer 102 can support the thick hard direct roof 20 and prevent the thick hard direct roof 20 from breaking;

[0026] One end of the caving chamber 15 is connected to the transport tunnel for air intake and transporting the discharged coal to the transport tunnel. The other end of the caving chamber 15 is connected to the return air tunnel for returning air. The transport chute 18 is connected to the transport tunnel, and the return air chute 17 is connected to the return air tunnel. The transport tunnel and the return air tunnel are not shown in the figure. The transport tunnel and the return air tunnel are well known in the art for coal mining and will not be described in detail here.

[0027] S2: If Figure 2 As shown, starting from the cut hole 13, the lower fully-mechanized mining layer 101 of the first working face is mined, and the lower fully-mechanized mining layer 101 is mined by using a coal mining machine in conjunction with a hydraulic support using the full caving method. The hydraulic support can be the hydraulic support used in the traditional one-time full-height mining, and there is no need to use the special hydraulic support for top coal caving mining technology of thick coal seams; after the lower fully-mechanized mining layer 101 is mined, the remaining upper caving layer 102 collapses into block coal (upper caving ore 103), and the volume increased by the crushing and expansion of the upper caving layer 102 is basically equal to or slightly smaller than the volume of the lower fully-mechanized mining layer 101, so that the block coal collapsed by the upper caving layer 102 can support the thick hard direct roof 20, thereby preventing the thick hard direct roof 20 from breaking;

[0028] S3: If Figure 3 As shown, a coal hopper 16 is constructed in the cut coal pillar 14 to discharge the upper caving ore 103 formed by the collapse of the upper caving layer 102. The upper caving ore 103 is discharged from the coal hopper 16 to the coal caving chamber 16 under the action of its own weight due to the inclination of the coal seam, and then transported out. A screw conveyor can also be used to assist in spirally conveying the upper caving ore 103 to the coal caving chamber 15.

[0029] In the process of releasing the upper collapsed ore 103, the upper collapsed ore 103 on the side of the withdrawal line 104 (the side away from the cutting eye 13) gradually decreases, forming a void area. Where the void area is formed, the thick hard direct roof 20 is intervened and the top is released; in the strike direction, the top cutting position is staggered inward by a certain distance from the mining boundary of the first working face, and the inner stagger distance is generally selected to be 5-15m ( Figure 2-3 In the inclination cutting top line 21); in the inclination, the cutting top is set at a set distance from the collection line 104, and the set distance can be about 20m ( Figure 2-3 The top cutting distance set on the trend of the top cutting line 22 in the direction should be much smaller than the fracture step distance of the thick hard direct roof 20 in the non-intervention situation. For example, the fracture step distance of the thick hard direct roof 20 is about 60m, and the top cutting distance on the trend after intervention is within 20m. After the top cutting, the top cutting block 23 formed by the thick hard direct roof 20 falls into the empty area formed by the mining of the coal seam 10. Since the top cutting width is smaller than the working face width and the thickness of the thick hard direct roof 20 is greater than the thickness of the coal seam 10, the thick hard direct roof 20 that falls into the empty area will form a top cutting staggered space 24 with the adjacent non-collapsed thick hard direct roof 20 and the section coal pillar 19. The top cutting staggered space 24 is mainly used as a pedestrian space. It can be used as a space for workers to perform top cutting operations when mining the upper collapsed ore 103, and it can also be used to assist in releasing the upper collapsed ore 103.

[0030] like Figure 4 As shown, the coal placing and top cutting operations are repeated until all the upper collapsed ores 103 are released and the thick hard direct tops in all the empty areas are cut off.

[0031] S4: As Figure 4 As shown, the top-cut staggered space 24 adjacent to the segmented coal pillar 19 of the second working face 12 is filled with filling material. The filling body 25 formed by the filling can play the role of the segmented coal pillar 19, thereby improving the stability of the existing segmented coal pillar 19, reducing the remaining width of the segmented coal pillar 19, and thus reducing coal loss.

[0032] S5: If Figure 4 As shown, the second working face 12 is mined with reference to steps S1-S4. Preferably, while the first working face 11 is being mined, the transport chute 18 and the cut hole 13 of the second working face are excavated simultaneously. After the first working face 11 is mined, the return air chute 17 of the second working face 12 is excavated and connected to the cut hole 13.

[0033] Of course, the above description is only a preferred embodiment of the present invention, and the present invention is not limited to the above-mentioned embodiments. It should be noted that all equivalent substitutions and obvious deformation forms made by any technician familiar with this field under the guidance of this specification fall within the substantive scope of this specification and should be protected by the present invention.

Claims

1. A method for controlling thick, hard, low-lying rock formations under high-intensity mining, characterized in that: The steps include: S1: Arrange several working faces along the coal seam, leaving segmented coal pillars between adjacent working faces; divide the coal seam into a lower fully-mechanized mining layer and an upper collapsed layer in terms of height; excavate a return air chute and a transport chute from the first working face in the lower fully-mechanized mining layer and open a cut to connect them; the cut is arranged at the lower part of the first working face, and coal chambers are arranged at intervals between the cut coal pillars in the lower part of the cut; S2: Use the full caving method to mine the lower fully mechanized mining layer of the first working face; S3: Construct a coal caving funnel in the cut coal pillar and discharge the upper caving ore into the coal caving chamber; in the process of discharging the upper caving ore, intervene with the thick and hard low-lying rock layer in the void area; in the strike direction, the top cutting position is staggered inward a certain distance from the mining boundary of the first working face; in the dip direction, the top cutting is carried out at a set interval starting from the withdrawal line; S4: Filling the top-cut staggered space adjacent to the second working surface with filling materials; S5: Mining the second working face with reference to steps S1-S4.

2. The method for controlling thick, hard, low-lying rock formations under high-intensity mining according to claim 1, characterized in that: It is applicable to the working conditions where the immediate roof is a thick, hard, low-lying rock formation, the coal seam thickness is large but smaller than the thickness of the thick, hard immediate roof, and the coal seam is a medium-inclined coal seam.

3. The method for controlling thick, hard, low-lying rock formations under high-intensity mining according to claim 1, characterized in that: In step S1, the heights of the lower fully-mechanized mining layer and the upper collapsed layer should satisfy the following requirements: after the lower fully-mechanized mining layer is mined, the upper collapsed layer collapses into block coal, and the increased volume of the upper collapsed layer is equal to or slightly smaller than the volume of the lower fully-mechanized mining layer.

4. The method for controlling thick, hard, low-lying rock formations under high-intensity mining according to claim 1, characterized in that: In step S2, the coal mining machine is used in conjunction with the hydraulic support to adopt the full caving method to mine the lower fully mechanized mining layer, and the hydraulic support adopts the hydraulic support used for mining the full height at one time.

5. The method for controlling thick, hard, low-lying rock formations under high-intensity mining according to claim 1, characterized in that: In step S5, while mining is being carried out on the first working face, excavation work is simultaneously carried out on the transport chute and cut eye of the second working face. After mining is completed on the first working face, excavation work is carried out on the return air chute of the second working face and connected to the cut eye.

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