A strip-column filling green coal mining method

Abstract

The present invention discloses a strip - pillar filling green coal mining method, belonging to the technical field of coal mine mining; the mining steps include pouring a number of artificial pillars in the goaf, and at the same time pouring a strip beside the roadway in the goaf along the auxiliary haulage gateway; effectively supporting the roof through the strip beside the roadway and the artificial pillars; the mining of the first sectional working face is carried out synchronously with the pouring of the strip beside the roadway and the artificial pillars; after the mining of the first sectional working face is completed and the paste of the strip beside the roadway and the paste of the artificial pillars are poured, a closed strip paste pouring mold is built for paste pouring; the goaf formed by the first sectional working face is sealed by the closed strip; the sealed goaf is densely filled; the present invention solves the problems of poor safety, low recovery rate and low filling rate in the mining of coal seams under shallow - buried non - fully caving areas by the existing filling mining methods.

Description

Technical Field

[0001] The present invention belongs to the technical field of coal mining and relates to a strip-pillar filling green coal mining method. Background Art

[0002] In western China, the coal resource reserves are extremely rich, mostly shallow-buried coal seams, with multiple coal seams and small coal seam spacing, all of which are nearly horizontal coal seams. In recent years, affected by factors such as the pull of coal market demand, high-intensity development in mining areas, and a substantial increase in coal production, the upper coal seams in the shallow-buried coal seam groups have been basically mined out, and the mining has gradually shifted to the lower coal seams.

[0003] Due to the diverse mining technologies and long mining time of the upper coal seams, different forms of goafs have been formed in the mining areas. Among them, the shallow-buried non-fully caving area and the remaining coal pillars in the area bring many adverse conditions to the mining of the lower coal seams: the stress distribution of the roof of the lower coal seams is uneven, the area under the coal pillars is a stress concentration area, and the area under the goaf is a stress release area; when mining the lower coal seams, if the roof cannot be effectively supported in a timely manner, it is easy to cause large-area caving of the goaf, and the surface settlement will damage the upper water system, thus triggering serious ecological environment damage and geological disasters.

[0004] In addition, a large amount of industrial solid waste of coal gangue is associated with coal production and washing processes. According to statistics, the stockpile of coal gangue in China has exceeded 7 billion tons, which is one of the industrial solid wastes with the largest stockpile, seriously affecting the surrounding ecological environment and the health of residents. How to handle and utilize coal gangue well has become an urgent problem to be solved for the clean and efficient utilization of coal.

[0005] Traditional filling mining methods have problems such as poor safety, low recovery rate, low filling rate, discontinuous mining and filling processes, and slow mining speed, and are not suitable for the mining of coal seams under shallow-buried non-fully caving areas. Therefore, it is of great significance and broad application prospects to invent a strip-pillar filling green coal mining method with high safety and efficiency, high recovery rate, high filling rate, continuous mining and filling, effective roof support, application of gob-side entry retaining technology, and large-scale utilization of coal gangue. Summary of the Invention

[0006] The present invention overcomes the deficiencies of the prior art and provides a strip-pillar filling green coal mining method, solving the technical problems of poor safety, low recovery rate, low filling rate, discontinuous mining and filling processes, and slow mining speed that occur when the existing filling mining method is used for mining coal seams under shallow-buried non-fully caving areas.

[0007] To achieve the above object, the present invention is realized by the following technical solutions:

[0008] A strip-pillar filling green coal mining method includes the following steps:

[0009] S1. Divide the fully mechanized mining face into several sectional working faces with a preset length according to the length of the fully mechanized mining face and the periodic weighting interval of the main roof.

[0010] S2. Drive three roadways along the fully mechanized mining face: the main haulage gateway, the auxiliary haulage gateway, and the cutting roadway.

[0011] S3. As the mining progresses, a goaf gradually forms in the first sectional working face; pour several artificial pillar pastes in the goaf, and at the same time pour strip paste beside the roadway in the goaf along the auxiliary haulage gateway; effectively support the roof through the strip beside the roadway and the artificial pillars; the mining of the first sectional working face is carried out simultaneously with the pouring of the strip paste beside the roadway and the artificial pillar paste.

[0012] S4. After the mining of the first sectional working face is completed and the pouring of the strip paste beside the roadway and the artificial pillar paste is completed, build a closed strip paste pouring mold and carry out paste pouring; seal the goaf formed by the mining of the first sectional working face through the closed strip.

[0013] S5. Densely fill the sealed goaf.

[0014] S6. Repeat steps S3 - S5 to sequentially carry out filling mining for the remaining sectional working faces.

[0015] Preferably, the fully mechanized mining face is composed of several continuous working faces. Divide each working face into several sectional working faces with a preset length; take the first working face as the first mining working face, and drive three roadways: the main haulage gateway of the first working face, the auxiliary haulage gateway of the first working face, and the cutting roadway of the first working face; drive two roadways for the remaining working faces: the auxiliary haulage gateway of the working face and the cutting roadway of the working face.

[0016] More preferably, the closed strip poured in the previous working face extends from the main haulage gateway of this working face to the connection point between the auxiliary haulage gateway of this working face and the adjacent next working face.

[0017] Preferably, the top of the closed strip is connected to the roof; a grouting port is provided on one side of the top of the closed strip, and an air return port is provided on the other side.

[0018] Preferably, yellow mud slurry is used for dense filling in step S5; the raw material ratio of the yellow mud slurry is coal gangue fine aggregate: loess: water = 1:0.2:1.1.

[0019] Preferably, the strip paste beside the roadway, the artificial pillar paste, and the closed strip paste have the same composition, and are all raw materials with the following ratio:

[0020] Coal gangue coarse aggregate: coal gangue fine aggregate: fly ash: cement: water: water reducing agent = 1:9:3:2:2:0.05; the particle size of the coal gangue coarse aggregate is 5 - 15 mm, and the particle size of the coal gangue fine aggregate is 0 - 5 mm.

[0021] Preferably, the thickness of the roadside strip and the outer diameter of the artificial pillar are calculated based on the load estimation method. Since the mining of the next adjacent working face will cause changes in the load characteristics of the previous roadside strip and artificial pillar, a dynamic load coefficient is introduced in the calculation. The calculation content is as follows:

[0022] Thickness of the roadside strip d The calculation formula is:

[0023]

[0024] The number of artificial pillars arranged in the goaf is N , and the sum of the support loads of all artificial pillars in the sectional working face is: , then the support load of a single artificial pillar is: ; According to the compressive strength P of the paste for the artificial pillar, the cross-sectional area of the artificial pillar is calculated as: , and then the outer diameter of the artificial pillar is calculated as: ;

[0025] In the formula: K - Dynamic load coefficient; d - Thickness of the roadside strip; b 1 - Width of the previous working face; b 2 - Width of the next adjacent working face; a - Length of the sectional working face; c - Width of the auxiliary haulage gateway of the previous working face; h is the average burial depth of the coal seam; δ is the caving angle of the overlying strata in the goaf; γ is the average unit weight of the overlying strata; P is the compressive strength of the paste for the strip.

[0026] Preferably, when the paste for the roadside strip, the paste for the artificial pillar, and the paste for the airtight strip are poured to reach the reserved empty roof height position, the pouring is stopped, and the remaining space is roofed by spraying concrete to increase the support strength.

[0027] Preferably, the preset length of the sectional working face is less than the periodic weighting interval of the main roof to prevent roof collapse during the mining process; the number of divisions of the sectional working face is determined according to the length of the fully mechanized working face and the preset length of the sectional working face.

[0028] Preferably, the pouring thickness of the paste for the airtight strip is not less than 1.5 m.

[0029] The beneficial effects of the present invention compared with the prior art are:

[0030] 1. The integrated mechanized coal mining without coal pillars and the strip-pillar paste filling are carried out simultaneously, which can improve the safety and recovery efficiency of coal mining operations, greatly increase the coal recovery rate of coal mines, extend the mine service life, and achieve the maximum utilization of coal resources.

[0031] 2. The high-strength filling of paste in the roadside strip and artificial mine pillars can effectively support the roof, prevent the overlying strata from caving, and protect the upper water system; the paste in the sealed strip seals the goaf, which can prevent the ventilation leakage from causing coal seam spontaneous combustion.

[0032] 3. The roadside strip paste for roof support can retain the auxiliary haulage gateway of the working face as the gob-side entry retaining for the main haulage gateway of the next working face.

[0033] 4. Using the method of shotcrete to achieve paste roof contact can increase the support strength.

[0034] 5. Using the gangue-based filling slurry as the paste filling material and using the yellow mud mainly composed of gangue to fill the goaf can scale and greenly process and utilize gangue, contributing to the green, low-carbon and high-quality development of coal; the filling rate of the goaf can reach more than 95%, solving the safety hazards of large-area goafs, controlling the ground pressure in the goaf to reduce ground subsidence, and effectively protecting the upper water system. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is the top view of the continuous working face in the embodiment;

[0036] Figure 2 is the schematic structural view of dividing the continuous working face into sectional working faces in the embodiment;

[0037] Figure 3 is the top view of the roadway driving of the continuous working face in the embodiment;

[0038] Figure 4 is the top view of the strip-pillar filling mining method of the working face in the embodiment;

[0039] Figure 5 is Figure 4 the schematic structural view of the sealed strip in

[0040] Figure 6 is the top view of the continuous working face after strip-pillar filling mining in the embodiment;

[0041] In the figure: 1. First working face; 2. Second working face; 3. Third working face; 11. Main haulage gateway of the first working face; 12. Auxiliary haulage gateway of the first working face; 13. Cutting roadway of the first working face; 22. Auxiliary haulage gateway of the second working face; 23. Cutting roadway of the second working face; 32. Auxiliary haulage gateway of the third working face; 33. Cutting roadway of the third working face; 4. Fully-mechanized mining equipment; 5. Goaf; 6. Rib strip; 7. Artificial pillar; 8. Sealing strip; 9. Roof; 10. Grouting port; 14. Return air inlet; 15. Yellow mud filling body. Specific implementation manner

[0042] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer and more understandable, the present invention will be further described in detail in combination with embodiments and drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. The technical solutions of the present invention will be described in detail below in combination with embodiments and drawings, but the protection scope is not limited hereby.

[0043] In this embodiment, the third mining area of a coal mine in Shanxi Province is used as the mining area for implementation. The structure of the third mining area is as Figure 1 shown, and three continuous working faces are arranged: the first working face 1, the second working face 2 and the third working face 3.

[0044] Refer to Figures 1 to 5 , and this embodiment proposes a strip-pillar filling green coal mining method, specifically the following steps:

[0045] Step 1, select the coal mining process: The continuous working face mining uses the pillarless fully-mechanized coal mining process, aiming to improve the safety, mining speed and recovery rate of coal mining operations, and realize the maximum utilization of coal resources.

[0046] Step 2, divide the sectional working face: According to the length of the fully-mechanized working face and the periodic weighting interval of the main roof, the fully-mechanized working face is divided into several sectional working faces with a preset length; as Figure 2 shown, in this embodiment, each of the three fully-mechanized working faces, namely the first working face 1, the second working face 2 and the third working face 3 in the third mining area, is divided into six sectional working faces (Ⅰ-Ⅵ).

[0047] Step 3, roadway driving of the working face for coal mining: As Figure 3 shown, in this embodiment, the first working face 1 is used as the first mining working face, and a total of three roadways are driven: the main haulage gateway 11 of the first working face, the auxiliary haulage gateway 12 of the first working face and the cutting roadway 13 of the first working face; two roadways are driven for the second working face 2: the auxiliary haulage gateway 22 of the second working face and the cutting roadway 23 of the second working face; two roadways are driven for the third working face 3: the auxiliary haulage gateway 32 of the third working face and the cutting roadway 33 of the third working face.

[0048] Step 4, strip-pillar filling mining of the first mining working face, asFigure 4 and Figure 5 As shown in and

[0049] , the mining steps are as follows:

[0049] a. First, mine the first working face 1. As the fully mechanized mining equipment 4 retreats for mining, the sectional working face Ⅰ in the first working face 1 gradually forms a gob 5. Build the paste casting molds for the artificial ore pillars 7 in the gob 5 and build the paste casting molds for the rib strips 6 along the auxiliary haulage gateway 12 of the first working face. Then, carry out paste casting, and the working face mining and paste casting are carried out simultaneously.

[0050] b. After the sectional working face Ⅰ in the first working face 1 is mined out and the paste casting of the rib strips 6 paste and the artificial ore pillars 7 paste is completed, build the paste casting molds for the airtight strip 8 and carry out paste casting. The airtight strip 8 extends from the main haulage gateway 11 of the first working face to the connection between the auxiliary haulage gateway 12 of the first working face and the second working face 2.

[0051] c. After the paste casting of the airtight strip 8 is completed, the gob 5 is sealed. Then, fill the gob 5. Use a shotcrete machine to inject the filling material into the gob 5 through the grouting port 10 reserved at the top of the airtight strip 8. The maximum spraying distance of the shotcrete machine is 200 m. After the gob 5 is filled, seal the grouting port 10 and the air return port 14 at the top of the airtight strip 8. The strip-pillar filling mining of the sectional working face Ⅰ in the first working face 1 is completed. The yellow mud filling body 15 is densely filled in the first working face 1.

[0052] d. Repeat steps a to c to carry out the strip-pillar filling mining of the sectional working faces Ⅱ - Ⅵ in the first working face 1.

[0053] Step 5. After the filling mining of the first working face 1 is completed, open a part of the airtight strip 8 cast for wind prevention in the auxiliary haulage gateway 12 of the first working face, use the auxiliary haulage gateway 12 of the first working face as the main haulage gateway of the second working face 2, and repeat step 4 to carry out the strip-pillar filling mining of the second working face 2. Similarly, use the auxiliary haulage gateway 22 of the second working face as the main haulage gateway of the third working face 3. Since the third working face 3 is the last working face, when repeating step 4 for strip-pillar filling mining, there is no need to fill the rib strips 6.

[0054] The strip-pillar filling layout after the full mining of the first working face 1, the second working face 2, and the third working face 3 is as shown in Figure 6 Figure 6 and

[0055] In step 2, the preset length of the sectional working face should be less than the periodic weighting interval of the main roof to prevent roof caving during the mining process. The number of divided sectional working faces should be determined according to the length of the fully mechanized mining face and the preset length of the sectional working face.

[0056] In step 4, the high-strength filling of the paste in the roadside strip 6 and the paste in the artificial pillar 7 can effectively support the roof, prevent the overlying strata from caving, and protect the upper water system. At the same time, the paste in the roadside strip 6 supporting the roof can retain the auxiliary haulage gateway 12 of the first working face as a gob-side entry retaining, which is used as the main haulage gateway of the second working face 2.

[0057] The paste in the sealed strip 8 can seal the gob 5, prevent the ventilation leakage from causing the spontaneous combustion of the coal seam, and has a certain bearing capacity. The pouring thickness of the paste in the sealed strip 8 is not less than 1.5 m.

[0058] In step 4, the paste filling material is selected as the coal gangue-based filling slurry, and its composition is: coal gangue, fly ash, cement, water and water reducer. The slurry ratio is coal gangue coarse aggregate: coal gangue fine aggregate: fly ash: cement: water: water reducer = 1:9:3:2:2:0.05. The particle size of the coal gangue coarse aggregate is 5 - 15 mm, and the particle size of the fine aggregate is 0 - 5 mm. The compressive strength of the paste P can reach 5 MPa.

[0059] In step 4, a filling station is built on the ground, and filling pipelines are arranged along the main haulage gateway 11 and the auxiliary haulage gateway 12 of the first working face. The coal gangue-based filling slurry is pumped through the filling pipelines to the gob 5 by using a filling pump.

[0060] In step 4, the thickness of the roadside strip 6 and the outer diameter of the artificial pillar 7 are calculated based on the load estimation method. Since the mining of the second working face 2 will cause changes in the load characteristics of the roadside strip 6 and the artificial pillar 7, a dynamic load coefficient is introduced in the calculation. The calculation content is as follows:

[0061] a. According to Figure 4 the relevant parameters of the working face shown, the thickness d of the roadside strip 6 of the first working face 1

[0062]

[0063] In the formula: K - Dynamic load coefficient; d - Thickness of the roadside strip 6, unit: m; b 1 - Width of the first working face, unit: m; b 2 - Width of the second working face, unit: m; a - Length of the sectional working face, unit: m; c - Width of the auxiliary haulage gateway 12 of the first working face, unit: m; h is the average buried depth of the coal seam, unit: m; δ is the caving angle of the overlying strata of the gob, °; γ is the average unit weight of the overlying strata, 0.025 MN / m 3 ; PThe compressive strength of the strip paste is 5 MPa;

[0064] b. Taking 20 as an example for the number of artificial ore pillars 7 arranged in the first working face 1 (sectional working face I) of this embodiment, according to Figure 4 the relevant parameters of the working face shown, the sum of the support loads of all artificial ore pillars 7 in the sectional working face I of the first working face 1 is calculated as: , then the support load of a single artificial ore pillar 7 is: ; According to the compressive strength P = 5 MPa of the paste of the artificial ore pillar 7, the cross-sectional area of the artificial ore pillar 7 is calculated as: , and then the outer diameter of the artificial ore pillar 7 is calculated as: .

[0065] In step 4, when the paste pouring reaches the reserved empty roof height position, the pouring is stopped, and the remaining space is roofed by spraying concrete to increase the support strength.

[0066] In step 4, the structure of the airtight strip 8 is as shown in Figure 5 . The top of the airtight strip 8 is connected to the roof 9; a grouting port 10 is reserved on the left side of the top for filling the goaf 5, and an air return port 14 is reserved on the right side for discharging the air in the goaf 5.

[0067] In step 4, the filling material for the goaf 5 is yellow mud with gangue as the main component. In order to improve the filling rate, gangue fine aggregate with a particle size of 0 - 5 mm is selected; the mixing ratio of the yellow mud is gangue fine aggregate: loess: water = 1:0.2:1.1; the loess has strong viscosity, poor water permeability, and good adsorption and water retention properties.

[0068] In step 4, using gangue-based filling slurry as the paste filling material and using yellow mud with gangue as the main component to fill the goaf 8 can scale and greenly process and utilize gangue, contributing to the green, low-carbon and high-quality development of coal; at the same time, the goaf filling rate can reach more than 95%, solving the safety hazards of large-area goafs, controlling the ground pressure in the goaf to reduce ground subsidence, and effectively protecting the upper water system.

[0069] The above content is a further detailed description of the present invention in combination with specific preferred embodiments. It cannot be determined that the specific embodiments of the present invention are limited to this. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the premise of the present invention, several simple deductions or substitutions can still be made, which should all be regarded as belonging to the patent protection scope determined by the claims submitted for the present invention.

Claims

1. A strip-column filling green coal mining method, characterized in that, It includes the following steps: S1. Divide the fully-mechanized mining face according to the length of the fully-mechanized mining face and the periodic weighting interval of the main roof: The fully-mechanized mining face is composed of several continuous working faces, and each working face is divided into several segmented working faces with a preset length; The first working face is taken as the first-mining working face, and three roadways are driven: the main haulage gateway (11) of the first working face, the auxiliary haulage gateway (12) of the first working face, and the cutting roadway (13) of the first working face; For the remaining working faces, two roadways are driven: the auxiliary haulage gateway of the working face and the cutting roadway of the working face. S2. Drive three roadways, namely the main haulage gateway, the auxiliary haulage gateway, and the cutting roadway, along the fully-mechanized mining face. S3. As the mining progresses, a goaf (5) gradually forms in the first segmented working face; Pour several paste artificial pillars (7) into the goaf (5), and at the same time pour paste rib strips (6) into the goaf (5) along the auxiliary haulage gateway; Effectively support the roof through the paste rib strips (6) and the paste artificial pillars (7); The mining of the first segmented working face is carried out synchronously with the pouring of the paste rib strips (6) and the paste artificial pillars (7). S4. After the mining of the first segmented working face is completed and the pouring of the paste rib strips (6) and the paste artificial pillars (7) is completed, build a pouring mold for the paste airtight strip (8) and carry out paste pouring; Seal the goaf (5) formed by the first segmented working face through the airtight strip (8). S5. Carry out dense filling of the sealed goaf (5). S6. Repeat steps S3 to S5 to carry out filling mining on the remaining segmented working faces in sequence. The thickness of the rib strip (6) and the outer diameter of the artificial pillar (7) are calculated based on the load estimation method. Since the mining of the adjacent next working face will cause changes in the load characteristics of the previous rib strip (6) and artificial pillar (7), a dynamic load coefficient is introduced in the calculation. The calculation content is as follows: Thickness of the roadside strip (6) d The calculation formula is as follows: The number of artificial ore pillars (7) arranged in the goaf (5) is N , and the sum of the support loads of all artificial ore pillars (7) in the sublevel working face is: , then the support load of a single artificial ore pillar (7) is: ; According to the compressive strength of the paste of the artificial ore pillar (7) P , the cross-sectional area of the artificial ore pillar (7) is calculated as: , and then the outer diameter of the artificial ore pillar (7) is calculated as: ; In the formula: K - Dynamic load coefficient; d - Thickness of the roadside strip; b 1 - Width of the previous working face; b 2 - Width of the adjacent next working face; - Length of the sectional working face; c - Width of the auxiliary haulage gateway of the previous working face; h is the average buried depth of the coal seam; δ is the caving angle of the overlying strata in the goaf; γ is the average unit weight of the overlying strata; P is the compressive strength of the strip paste.

2. The strip-pillar filling green coal mining method according to claim 1, wherein The airtight strip (8) poured in the previous working face extends from the main haulage gateway of this working face to the connection with the auxiliary haulage gateway of the adjacent next working face.

3. A strip-pillar filling green coal mining method according to claim 1 or 2, characterized in that The top of the airtight strip (8) is connected to the roof (9); A grouting port (10) is provided on one side of the top of the airtight strip (8), and an air return port (14) is provided on the other side.

4. A strip-pillar filling green coal mining method according to claim 1, characterized in that, In step S5, yellow mud slurry is used for dense filling; The raw material ratio of the yellow mud slurry is coal gangue fine aggregate: loess: water = 1:0.2:1.

1.

5. The strip-pillar filling green coal mining method according to claim 1, wherein The paste rib strip (6), the paste artificial pillar (7), and the paste airtight strip (8) have the same composition and are all made of raw materials with the following ratio: Coal gangue coarse aggregate: coal gangue fine aggregate: fly ash: cement: water: water reducer = 1:9:3:2:2:0.05; The particle size of the coal gangue coarse aggregate is 5 - 15 mm, and the particle size of the coal gangue fine aggregate is 0 - 5 mm.

6. The strip-column filling green coal mining method according to claim 1, characterized in that, When the pouring of the paste rib strip (6), the paste artificial pillar (7), and the paste airtight strip (8) reaches the reserved empty roof height position, stop pouring, and the remaining space is connected to the roof by spraying concrete to increase the support strength.

7. The pillar-strip filling green coal mining method according to claim 1, characterized in that, The preset length of the sectional working face is less than the periodic weighting interval of the main roof to prevent the roof from caving during the mining process; the number of divided sectional working faces is determined according to the length of the fully mechanized mining face and the preset length of the sectional working face.

8. A strip-pillar filling green coal mining method according to claim 1, characterized in that, The casting thickness of the paste in the airtight strip (8) is not less than 1.5 m.

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