A mining method for recovering coal to a stop-mining line without setting a safety coal pillar

Abstract

The present invention discloses a mining method for recovering coal to a stop-mining line without setting up a safety coal pillar, which belongs to the technical field of coal mining. The mining method first expands the wall on one side of a transport tunnel in a mining area to form an expanded wall area; then casts a concrete retaining wall in the expanded wall area; opens a top-cutting pressure relief hole on one side of the concrete retaining wall and on the roof above the safety coal pillar; after the concrete retaining wall reaches a set strength, the safety coal pillar is started to be recovered; the top of the coal seam is cut and pressure relieved by blasting the top-cutting pressure relief hole; when the recovery work advances to the concrete retaining wall, the mining equipment and the support are withdrawn; and the roof on the support is collapsed; the present invention can realize the reasonable optimization combination of the movement and deformation of the overlying strata on the roadway roof and the coal seam roof and the surrounding mining layout, so as to achieve the goal of not leaving a safety coal pillar when mining a coal seam group or a combined coal seam group, and realize the stability of the overlying strata on the roadway roof and the coal seam roof.

Description

Technical Field

[0001] The invention belongs to the technical field of coal mining, and in particular relates to a mining method for recovering coal to a stop mining line without setting a safety coal pillar. Background Art

[0002] Coal resources are an important fossil energy source and a non-renewable energy source. They occupy a dominant position in my country's energy structure. The mining and use of coal have a significant impact on my country's economic development and the improvement of people's living standards.

[0003] The protection of coal resources also helps improve the economic and social benefits of coal enterprises. Rational mining and utilization of coal resources can increase coal utilization, reduce waste and losses, and improve the economic benefits of enterprises. It can also enhance the social image of coal enterprises and strengthen their competitiveness.

[0004] With the continuous advancement of coal mining technology, people have placed higher demands on the efficient utilization of coal resources. The development of pillarless mining technology can be traced back to the 1990s, when the coal industry began exploring ways to reduce the environmental impact of coal mining and improve the utilization of coal resources. The development of pillarless mining technology can be roughly divided into three stages: the initial exploration stage, the gradual promotion and application stage, and the intelligent technology development stage. During the initial exploration stage, coal companies began to attempt to reduce coal pillar loss during the coal mining process and improve the recovery rate of coal resources. During the gradual promotion and application stage, pillarless mining technology was widely used and achieved good economic and social benefits. During the intelligent technology development stage, with the continuous advancement of intelligent technology, the intelligence level of pillarless mining technology has continued to increase, enabling more precise mining and management.

[0005] However, when applying the existing pillar-free mining technology, it is still necessary to set up safety coal pillars when mining to the stop-mining line. When mining reaches the stop-mining line, the coal side of the stop-mining line is reinforced by grouting, and the size of the safety coal pillar is reduced, so as to achieve mining with a small coal pillar. In addition, traditional metal pillars and top beams can also be used to improve the support effect and mining efficiency. These technical means can effectively reduce the loss of coal pillars during coal mining and improve the recovery rate of coal resources. However, it can only achieve small coal pillar mining and cannot achieve complete pillar-free mining for the safety coal pillar. After leaving a small coal pillar, there is still the problem of high maintenance cost, and it is easy to cause safety accidents such as spalling and roof collapse under the damage of mining. Summary of the Invention

[0006] The present invention overcomes the shortcomings of the existing technology and proposes a mining method that does not set up safety coal pillars when mining to the stop line; so as to achieve coal pillar-free mining without setting up safety coal pillars when the coal mining working face is mined to the stop line.

[0007] In order to achieve the above object, the present invention is achieved through the following technical solutions:

[0008] A mining method for recovering coal to a stop-mining line without setting a safety coal pillar, wherein a mining area transport tunnel is arranged on one side of the recovery working face; a stop-mining line is arranged on the side of the recovery working face adjacent to the mining area transport tunnel; a safety coal pillar is left at the stop-mining line; mining equipment and supports are arranged on the recovery working face, and recovery is carried out on the recovery working face, comprising the following steps:

[0009] Step 1: Expand the side of the transport tunnel in the mining area close to the mining working face to form an expanded area;

[0010] Step 2: Concrete is poured in the expanded area to form a concrete retaining wall; a row of top-cutting pressure relief holes is opened on the roof between the concrete retaining wall and the safety coal pillar; a row of top-cutting pressure relief holes is also opened on the roof of the safety coal pillar adjacent to the support; multiple rows of top-cutting pressure relief holes are opened between the two rows of top-cutting pressure relief holes and on the roof of the safety coal pillar;

[0011] Step 3: After the concrete retaining wall reaches the set strength, start mining the safety coal pillar; cut the top of the coal seam and relieve pressure by blasting the top pressure relief holes;

[0012] Step 4: When the mining work reaches the concrete retaining wall, start withdrawing the mining equipment and supports; and cause the top plate on the supports to collapse; forming a mining void area behind the concrete retaining wall.

[0013] Furthermore, the expansion is carried out when the mining face is mined to the stop mining line, or before or during the mining process of the mining face.

[0014] Furthermore, the spacing and depth of the top-cut pressure relief holes, as well as the charge amount of each top-cut pressure relief hole are determined according to the lithology of the coal seam roof.

[0015] Furthermore, in step four, when the top plate on the support does not collapse in time, a new top-cutting pressure relief hole is drilled and blasted on the top plate above the concrete retaining wall on the side of the mining area transport tunnel close to the concrete retaining wall, facing the goaf and falling area, to cut the top plate above the concrete retaining wall and relieve the pressure.

[0016] Furthermore, the angle of the new top-cut pressure relief hole is 10° to 20° away from the vertical direction.

[0017] Furthermore, the depth of the new top-cutting pressure relief hole is greater than 3 times the width of the mining area transport tunnel; the top plate outside the range of 5 meters above the concrete retaining wall is blasted and cut through the new top-cutting pressure relief hole.

[0018] Furthermore, in step four, the goaf and collapse area formed behind the concrete retaining wall is formed by the collapse of the roof, and the height of the collapsed roof is greater than 3 times the width of the mining area transport tunnel.

[0019] Furthermore, after step four, grouting holes are drilled toward the goaf and caving area on one side of the mining area transport tunnel close to the concrete retaining wall, and then the goaf and caving area is filled with grouting.

[0020] Furthermore, the elevation angle of the grouting hole is 40°~50°.

[0021] Furthermore, the mass percentages of materials used for grouting filling are: cement 0-20%, fly ash 30-60%, coal gangue or construction waste 30-60%; the particle size of the coal gangue and construction waste is less than 3mm.

[0022] The beneficial effects of the present invention compared to the prior art are:

[0023] The present invention can achieve a rational and optimized combination of the movement and deformation of the overlying strata on the roadway roof and coal seam roof, and the surrounding mining layout, so that no safety coal pillars are left when mining a coal seam group or a combination of coal seams, and the overlying strata on the roadway roof and coal seam roof are stabilized. By controlling the collapse position of the roadway roof and overlying strata in the goaf, the purpose of safe mining is achieved.

[0024] Behind the established concrete retaining wall, the overburden in the goaf is reinforced by grouting to enhance the stability of the roadway roof and the overburden in the goaf, thereby achieving the goal of safe mining. At the same time, the coal recovery rate and work efficiency are improved, the difficulty of work is reduced, and production costs and safety risks are reduced.

[0025] In summary, the pillarless mining construction technology that does not set up safety coal pillars when the coal mining face is mined to the stop line can create huge economic benefits and contribute to social benefits for protecting non-renewable resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is the location plan of the stop mining line and safety coal pillar;

[0027] Figure 2 This is a structural elevation diagram of the first mining face after setting up the support and starting mining in step 1 of the embodiment;

[0028] Figure 3 This is a structural elevation diagram of the goaf and caving area formed in step 1 of the embodiment;

[0029] Figure 4 This is a structural elevation diagram after expansion in step 1 of the embodiment;

[0030] Figure 5 This is a structural elevation diagram after the top-cutting pressure relief hole is opened in step 2 of the embodiment;

[0031] Figure 6 This is a structural elevation diagram after the safety coal pillar is mined in step three of the embodiment;

[0032] Figure 7 This is a structural elevation diagram of a new top-cut pressure relief hole in step 4 of the embodiment;

[0033] Figure 8 This is a structural elevation diagram after the top plate above the concrete retaining wall is blasted in step five of the embodiment;

[0034] Figure 9 This is a structural elevation diagram of the grouting filling in the goaf and caving area in step six of the embodiment;

[0035] In the figure: 1. Mining working face; 2. Auxiliary transport tunnel in mining area; 3. Return air tunnel in mining area; 4. Transport tunnel in mining area; 5. Stop mining line; 6. Safety coal pillar; 7. Support; 8. Goaf and caving area; 9. Expanded wall area; 10. Concrete retaining wall; 11. Top cut pressure relief hole; 12. Grouting hole; 13. Grouting filling body. DETAILED DESCRIPTION

[0036] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail with reference to the embodiments and the accompanying drawings. It should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention. The technical solutions of the present invention will be described in detail below with reference to the embodiments and the accompanying drawings, but the scope of protection is not limited thereto.

[0037] like Figure 1 As shown, there are multiple mining faces 1 underground, and on one side of the multiple mining faces 1, there are arranged in sequence the mining area auxiliary transport tunnel 2; the mining area return air tunnel 3; the mining area transport tunnel 4; a stop mining line 5 is set on one side of the multiple mining faces 1 adjacent to the mining area transport tunnel 4; in the mining process, after mining using existing technology, the position of the stop mining line 5 is reached, and a safety coal pillar 6 needs to be set; the safety coal pillar 6 of a shallowly buried mine is generally left at more than 50 meters, and the safety coal pillar 6 of a deep mine is generally left at more than 100 meters.

[0038] This embodiment proposes a mining method for recovering coal to a stop-mining line without setting a safety coal pillar, comprising the following steps:

[0039] Step 1: Figure 2 As shown, the required mining equipment and support 7 are arranged on the mining face 1; the first mining face 1 is mined, and a goaf area 8 (such as Figure 3 As shown); When mining reaches the stop line 5, the side of the mining area transport tunnel 4 close to the mining working face 1 is expanded to form an expanded area 9 (as shown); Figure 4 shown).

[0040] It should be noted that the expansion can also be done in advance when mining the first mining face 1.

[0041] Step 2: Figure 5 As shown, after the wall of the mining area transport tunnel 4 is expanded, pouring is carried out in the expanded area 9 to form a concrete retaining wall 10; a row of top cutting pressure relief holes 11 are opened on the roof immediately behind the concrete retaining wall 10 (i.e., between the concrete retaining wall 10 and the safety coal pillar 6).

[0042] In order to better protect the concrete retaining wall 10, a row of top-cutting pressure relief holes 11 is also opened on the top plate of the safety coal pillar 6 adjacent to the support 7; multiple rows of top-cutting pressure relief holes 11 are opened between the two rows of top-cutting pressure relief holes 11 and on the top plate of the safety coal pillar 6; and explosives are installed in the top-cutting pressure relief holes 11.

[0043] The spacing and depth of the roof cut pressure relief holes 11 and the charge amount of each roof cut pressure relief hole 11 are determined according to the lithology of the coal seam roof.

[0044] In this embodiment, according to the lithology of the coal seam roof and the method of top cutting and pressure relief blasting, the spacing between the top cutting and pressure relief holes 11 is set to 1.5 meters and the row spacing is 2 meters. In this embodiment, the width of the mining area transportation tunnel 4 is 4 meters. Since the depth of the top cutting and pressure relief holes 11 must be more than 3 times that of the mining area transportation tunnel 4, the depth of the top cutting and pressure relief holes 11 is set to 15 meters based on the lithology calculation.

[0045] Step 3: Figure 6 As shown, after the concrete retaining wall 10 reaches the set strength, the safety coal pillar 6 is mined, and the mining work continues to advance to the concrete retaining wall 10. The blasting time of the top cutting pressure relief hole 11 must be synchronized with the advancement speed of the mining work, and the top of the coal seam is cut and pressure-relieved through the top cutting pressure relief hole 11; during the mining process, a goaf and caving area 8 is gradually formed behind the support 7.

[0046] Step 4: Figure 7 As shown, when the mining work advances to the concrete retaining wall 10, the working face equipment, support 7 and other facilities begin to be withdrawn. While withdrawing the support 7, the collapse of the roof on the support 7 should be observed. If the collapse is not timely, it is necessary to drill a new top-cutting pressure relief hole 11 on the top plate above the concrete retaining wall 10 in the mining area transport tunnel 4 near the concrete retaining wall 10, toward the goaf and fall area 8 and deviate from the vertical direction by 10°~20° (the angle can be adjusted) and blast it, or use other methods to cut the top plate above the concrete retaining wall 10 to relieve pressure.

[0047] The depth of the new top-cutting pressure relief hole 11 is set to more than 3 times the width of the mining area transport tunnel 4, and the top slab outside the range of 5 meters above the concrete retaining wall 10 shall not be blasted and cut; if the top slab within the range of 5 meters above the concrete retaining wall 10 is blasted and cut, the top slab of the mining area transport tunnel 4 may collapse after the support 7 is withdrawn.

[0048] Step 5: Figure 8As shown, after the top plate above the concrete retaining wall 10 is blasted or other methods are used to cut the top and release the pressure, the goaf and fall area 8 behind the concrete retaining wall 10 is formed by the collapse of the top plate, and the height of the collapsed top plate is greater than 3 times the width of the mining area transport tunnel 4.

[0049] Then, a grouting hole 12 is drilled on one side of the mining area transport tunnel 4 close to the concrete retaining wall 10 toward the goaf and caving area 8 at an elevation angle of 45° (the angle can be adjusted).

[0050] Step 6: Figure 9 As shown, after the grouting holes 12 are drilled in the goaf and caving area 8, the goaf and caving area 8 is filled with grouting.

[0051] Specifically, the mined-out area 8 within a range of 15 meters is reinforced by grouting to form a grouting filling body 13. The grouting filling material can be a cementitious or non-cementitious material, and the mass percentage of the material is: cement 0-20%, fly ash 30-60%, coal gangue or construction waste 30-60%; and the particle size of the coal gangue and construction waste is both <3mm.

[0052] If the coal seam roof and floor have a sufficiently strong supporting strength, or the concrete retaining wall 10 is strong enough, the steps of drilling the grouting holes 12 and grouting can be omitted.

[0053] Step 7: Loop through steps 1 to 6 to complete the mining of all mining faces 1 and the safety coal pillars 6.

[0054] The above content is a further detailed description of the present invention in combination with a specific preferred embodiment. It cannot be considered that the specific embodiments of the present invention are limited to this. For ordinary technicians in the technical field to which the present invention belongs, they can make several simple deductions or substitutions without departing from the present invention, which should be regarded as belonging to the scope of patent protection determined by the submitted claims of the present invention.

Claims

1. A mining method for recovering coal to a stop-mining line without setting a safety coal pillar, wherein a mining area transport tunnel (4) is arranged on one side of a recovery working face (1); a stop-mining line (5) is arranged on one side of the recovery working face (1) adjacent to the mining area transport tunnel (4); a safety coal pillar (6) is left at the stop-mining line (5); mining equipment and supports (7) are arranged on the recovery working face (1) and recovery is carried out on the recovery working face (1), characterized in that: The following steps are involved: Step 1: Expand the side of the mining area transport tunnel (4) close to the mining working face (1) to form an expanded area (9); Step 2: Concrete is poured in the expanded area (9) to form a concrete retaining wall (10); a row of top-cutting pressure relief holes (11) is opened on the top plate between the concrete retaining wall (10) and the safety coal pillar (6); a row of top-cutting pressure relief holes (11) is also opened on the top plate of the safety coal pillar (6) adjacent to the support (7); and multiple rows of top-cutting pressure relief holes (11) are opened between the two rows of top-cutting pressure relief holes (11) and on the top plate of the safety coal pillar (6); Step 3: After the concrete retaining wall (10) reaches the set strength, start mining the safety coal pillar (6); cut the top of the coal seam and release the pressure by blasting the top pressure relief hole (11); Step 4: When the mining work reaches the concrete retaining wall (10), the mining equipment and the support (7) are withdrawn; the top plate on the support (7) collapses; and a mining area (8) is formed behind the concrete retaining wall (10).

2. A mining method according to claim 1, wherein the mining method is characterized in that: The expansion is carried out when the mining face (1) is mined to the stop mining line (5), or before or during the mining of the mining face (1).

3. A mining method according to claim 1, wherein the mining method is characterized in that: The spacing and depth of the top-cut pressure relief holes (11) and the charge amount of each top-cut pressure relief hole (11) are determined according to the lithology of the coal seam roof.

4. The mining method according to claim 1, wherein the mining method is characterized in that: In step 4, when the top plate on the support (7) does not collapse in time, a new top-cutting pressure relief hole (11) is drilled on the top plate above the concrete retaining wall (10) on the side of the mining area transport tunnel (4) close to the concrete retaining wall (10) and blasted toward the goaf and fall area (8), thereby cutting and relieving the pressure on the top plate above the concrete retaining wall (10).

5. A mining method according to claim 4, wherein the mining method is characterized in that: The angle of the new cut-top pressure relief hole (11) is 10° to 20° away from the vertical direction.

6. A mining method according to claim 4, wherein the method is characterized in that: The depth of the new top-cutting pressure relief hole (11) is greater than three times the width of the mining area transport tunnel (4); the top plate outside the range of 5 meters above the concrete retaining wall (10) is blasted and cut through the new top-cutting pressure relief hole (11).

7. The mining method according to claim 1, wherein the mining method is characterized in that: In step 4, the goaf and fall area (8) formed behind the concrete retaining wall (10) is formed by the collapse of the roof, and the height of the collapsed roof is greater than 3 times the width of the mining area transport tunnel (4).

8. The mining method according to claim 1, wherein the mining method does not set up a safety coal pillar until the mining stop line is reached, After step 4, a grouting hole (12) is drilled toward the goaf and caving area (8) on one side of the mining area transport tunnel (4) close to the concrete retaining wall (10), and then the goaf and caving area (8) is filled with grouting.

9. A mining method according to claim 8, wherein the mining method is characterized in that: The elevation angle of the grouting hole (12) is 40°~50°.

10. A mining method for recovering coal to a stop-mining line without setting a safety coal pillar according to claim 8, characterized in that: The mass percentages of materials used for grouting filling are: cement 0-20%, fly ash 30-60%, coal gangue or construction waste 30-60%; the particle size of coal gangue and construction waste is less than 3mm.

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