A method for designing process parameters for top coal caving in coal pillars at large inclination angles and extremely close distances

Abstract

The application discloses a large-dip-angle extremely close section coal pillar top coal drawing process parameter design method, which comprises the following steps: arranging the fully-mechanized hydraulic support in the lower working face to draw out the overlying section coal pillar; then, a large-dip-angle extremely close section coal pillar top coal drawing numerical model is established; firstly, the drawing rate alpha1 and the gangue content beta1 of the section coal pillar are simulated and calculated when the drawing step phi is different, the relationship between the drawing step phi and the drawing rate alpha1 and the gangue content beta1 is obtained, and the optimal drawing step phi' is determined; then, the drawing rate alpha2 and the gangue content beta2 of the section coal pillar are researched based on the optimal drawing step phi', the relationship between the drawing mode and the drawing rate alpha2 and the gangue content beta2 is obtained, and the optimal drawing mode is determined. The method can provide a reference for the large-dip-angle extremely close section coal pillar top coal drawing process parameter design, realizes the full mining of the coal resources without the coal pillar, improves the top coal drawing rate, has high economy and practicability, and has a wide application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of top coal caving, and in particular relates to a method for designing process parameters for top coal caving in a coal pillar in a large-angle and extremely close-distance section. Background Art

[0002] For a long time, coal has accounted for approximately 70% of disposable energy production and consumption. Despite efforts in recent years to promote the diversification of the energy structure, coal's dominant position in primary energy production and consumption will not change for a long time. However, most mines currently still use the method of retaining segmented coal pillars for working face coal mining operations. The width of the segmented coal pillars often reaches 30 to 40 meters or more, resulting in a large waste of coal resources. At the same time, in recent years, the focus of coal resource development has gradually shifted from the east to the west. The coal seams in the western region are mostly distributed in the form of steeply inclined, thick and extra-thick coal seams, which are difficult to mine. Therefore, the rational selection of top coal caving process parameters has become a top priority. In the existing technology, there are still major problems in recovering segmented coal pillars at steep angles and implementing top coal caving processes. Summary of the Invention

[0003] Purpose of the invention: The purpose of the present invention is to provide a method for designing process parameters for top coal caving in coal pillars in sections with large inclination angles and extremely close distances. This design method is simple and easy to implement, with high accuracy, and can provide a reference for the design of process parameters for top coal caving, thereby optimizing the coal caving process in coal pillars in sections with large inclination angles and extremely close distances.

[0004] Technical Solution: The present invention provides a method for designing process parameters for top coal caving in a high-angle, extremely close-distance coal pillar. After driving a transport tunnel, a return air tunnel, and a cut in the close-distance coal seam below the target section coal pillar, a fully-mechanized caving hydraulic support is arranged in the lower working face to caving out the overlying section coal pillar. A numerical model for top coal caving in a high-angle, extremely close-distance coal pillar section is established using simulation software, and the optimal caving method is determined based on the model. Finally, the top coal caving process parameters are designed in combination with actual engineering geological parameters. The method specifically includes the following steps:

[0005] Step 1: According to the layout of fully mechanized caving mining tunnels, transport tunnels, return air tunnels and cut holes are excavated in the working face below the overlying coal pillar. Fully mechanized caving supports are arranged in the working face, and the top coal caving technology is used to caving out the overlying coal pillar together.

[0006] Step 2: Collect data on the working face and roof and floor strata to determine the section coal pillar width L, height H1, gangue height H2, underlying coal seam height H3, and the distance between the coal transport roadway and the return air roadway and the section coal pillar. Based on the physical and mechanical parameters of the coal and rock in the working face area, a numerical model for top coal caving in the section coal pillar with a large dip angle and extremely close distance is established using simulation software.

[0007] Step 3: Based on the numerical model of top coal caving in the high-inclination and extremely close-distance section coal pillar, calculate the section coal pillar caving rate α1 and gangue content β1 at different caving step distances φ. According to the numerical simulation results, the relationship between caving step distance φ and caving rate α1 and gangue content β1 is obtained, and the optimal caving step distance φ' is determined;

[0008] Step 4: Study different coal caving methods based on the optimal coal caving step distance φ' The coal pillar discharge rate α2 and gangue content β2 in the time zone are calculated based on the numerical simulation results to obtain the coal discharge method. Determine the optimal coal discharge method based on the relationship between discharge rate α2 and gangue content β2

[0009] Step 5: Optimal coal placement The top coal caving process parameters are designed in combination with actual engineering geological parameters.

[0010] Furthermore, in step 2, the gangue height H2 is 0m-1.0m to reduce the gangue content and improve the coal caving effect of the overlying section coal pillar.

[0011] Furthermore, in step 2, the simulation software is PFC discrete element numerical simulation software.

[0012] Furthermore, in step 3, the range of the release rates α1 and α2 is 80%-100% to improve the release rate of the coal pillar in the section.

[0013] Furthermore, in step 3, the range of the gangue content β1 and β2 is 0%-5% to reduce the cost and difficulty of gangue separation.

[0014] Furthermore, step 3 is specifically as follows:

[0015] α1=M1 / M0

[0016] β1=M2 / (M1+M2)

[0017] Where: M0 - total mass of coal in one coal placement step, kg;

[0018] M1——total mass of coal in the discharge body, kg;

[0019] M2——Total mass of gangue in the discharge body, kg;

[0020] The optimal coal discharge step is to select the maximum discharge rate within 5% of the gangue content.

[0021] Furthermore, step 4 is specifically as follows:

[0022] α2=M1 / M0

[0023] β2=M2 / (M1+M2)

[0024] Where: M0 - total mass of coal in one coal placement step, kg;

[0025] M1——total mass of coal in the discharge body, kg;

[0026] M2——Total mass of gangue in the discharge body, kg;

[0027] The optimal coal discharge method is to select the maximum discharge rate within 5% of the gangue content.

[0028] Beneficial effects: Compared with the existing technology, the present invention has the following significant advantages: the method for designing process parameters for caving top coal in large-angle and extremely close-distance sections of coal pillars of the present invention can not only recover the section coal pillars when mining large-angle and extremely close-distance thick and extra-thick coal seams, but also, in actual application, only needs to determine the actual engineering conditions of the working face mining and the lithology of the top and bottom plate rock layers, and can then obtain the optimal coal caving step distance and coal caving method based on numerical simulation research, thereby optimizing the coal caving process. This method provides a reference for the recovery of large-angle and extremely close-distance sections of coal pillars, and provides a theoretical reference for the design method for process parameters for caving top coal in large-angle and extremely close-distance sections of coal pillars. This design method is simple and easy to implement, with high accuracy, and can provide a reference for the design of top coal caving process parameters, realizing the optimization of the coal caving process of large-angle and extremely close-distance sections of coal pillars. It has strong technical innovation, is easy to operate, has high economy and practicality, and has a very broad application prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is the layout of the coal pillar top coal caving working face in the large-angle and extremely close-distance section of the present invention.

[0030] Figure 2 This is the numerical calculation model for top coal caving in coal pillars in large-angle and extremely close-distance sections of the present invention.

[0031] Figure 3 This is the relationship curve between the coal caving step distance φ and the section coal pillar caving rate α1 and the gangue content β1 of the present invention.

[0032] Figure 4 The coal placing method of the present invention Relationship curve between coal pillar discharge rate α2 and gangue content α2 in time section.

[0033] In the figure, 1-segmental coal pillar; 2-return air lane; 3-fully-mechanized caving working face; 4-fully-mechanized caving support; 5-gangue. DETAILED DESCRIPTION

[0034] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0035] Example 1, taking a mine as an example, the specific implementation steps are as follows:

[0036] A mine in a certain mining area has a designed production capacity of 6.00 Mt / a. The main mining seams are 1# and 2# coal seams. 1# coal is coking coal and has a high mining value. The coal seam thickness is 3 to 4 meters, with an average thickness of 3.5 meters. However, in the early stages of the mine, considering the impact of strong mining stress and the soft rock support conditions in the roof and floor, a section of coal pillars approximately 40 meters long was left during the working face, resulting in a significant waste of coal resources. 2# coal seam thickness is 2.6 to 4.2 meters, with an average thickness of 3.0 meters. The coal seam dips at 30°, making it a steeply inclined, thick coal seam with an average burial depth of 300 meters. There is 1 meter of gangue between 1# and 2# coal seams. The fully mechanized caving working face has an inclination length of 200 meters and an advance length of 800 meters.

[0037] (1) According to the layout of the fully mechanized caving mining roadway, the cutting eye, coal transportation roadway and return air roadway are excavated in the working face below the overlying section coal pillar, and the fully mechanized caving support is arranged in the working face to release the overlying section coal pillar together;

[0038] (2) Collect the rock data of the working face and the roof and floor, determine the width of the coal pillar L = 40m, height H1 = 3.5m, gangue height H2 = 1m, the height of the underlying coal seam H3 = 3m, and the distance between the coal transport roadway and the return air roadway and the section coal pillar is 20m, test the physical and mechanical properties of the coal rock samples in the fully mechanized caving working face area, and obtain the physical and mechanical parameters of the coal rock mass (see Table 1). Use the PFC discrete element numerical simulation software to establish a numerical model of the coal pillar in the large-angle and extremely close-distance section, as shown in the following example: Figure 2 As shown;

[0039] Table 1 Physical and mechanical parameters of coal rock mass

[0040]

[0041] (3) The coal pillar discharge rate α1 and gangue content β1 of the section with different coal caving step distances φ are studied, as shown in the following formula. Five schemes are designed, with coal caving step distances of 0.8m, 1.6m, 2.4m, 3.2m and 4m respectively. The results of top coal discharge rate and gangue content are shown in Table 2. The relationship curve is shown in Figure 3 shown.

[0042] α1=M1 / M0

[0043] β1=M2 / (M1+M2)

[0044] Where: M0 - total mass of coal in one coal placement step, kg;

[0045] M1——total mass of coal in the discharge body, kg;

[0046] M2——Total mass of gangue in the discharge body, kg;

[0047] Table 2 Statistics of top coal discharge rate and gangue content

[0048]

[0049] According to Table 2 and Figure 3 The coal discharge rate α1 is greater than 80% and the gangue content β1 is less than 5%, so the coal discharge step distance φ'=1.6m is selected as the optimal coal discharge step distance.

[0050] (4) Study different coal caving methods based on the optimal coal caving step distance φ' = 1.6m The coal pillar discharge rate α2 and the gangue content β2 in the time zone are shown in the following formula. Three schemes are designed. The coal discharge methods are one mining and one discharge, two mining and one discharge, and three mining and one discharge. The statistics of the top coal discharge rate and gangue content are shown in Table 3. The relationship curve is shown in Figure 4 shown.

[0051] α2=M1 / M0

[0052] β2=M2 / (M1+M2)

[0053] Where: M0 - total mass of coal in one coal placement step, kg;

[0054] M1——total mass of coal in the discharge body, kg;

[0055] M2——Total mass of gangue in the discharge body, kg;

[0056] Table 3 Statistics of top coal discharge rate and gangue content

[0057]

[0058] According to Table 3 and Figure 4 The discharge rate α2 is greater than 80% and the gangue content β2 is less than 5%, so the optimal coal discharge step is selected. One picking and one releasing.

[0059] (5) In summary, the coal caving step distance φ' = 1.6m and the coal caving step distance It is a one-time mining and one-time releasing process, with the final releasing rate and gangue content being 85% and 4.2% respectively.

Claims

1. A method for designing process parameters for top coal caving in a coal pillar at a large angle and very close distance, characterized in that: After driving a transport tunnel, a return air tunnel, and a cut in the close-range coal seam below the target section's coal pillar, a fully mechanized caving hydraulic support is deployed in the lower working face to caving out the overlying section's coal pillar. A numerical model for top coal caving in a high-angle, extremely close-range section of the coal pillar is established using simulation software. Based on this model, the optimal caving method is determined. Finally, the top coal caving process parameters are designed based on actual engineering geological parameters. This process specifically involves the following steps: Step 1: According to the layout of fully mechanized caving mining tunnels, transport tunnels, return air tunnels and cut holes are excavated in the working face below the overlying coal pillar. Fully mechanized caving supports are arranged in the working face, and the top coal caving technology is used to caving out the overlying coal pillar together. Step 2: Collect data on the working face and roof and floor strata to determine the section coal pillar width L, height H1, gangue height H2, underlying coal seam height H3, and the distance between the coal transport roadway and the return air roadway and the section coal pillar. Based on the physical and mechanical parameters of the coal and rock in the working face area, a numerical model for top coal caving in the section coal pillar with a large dip angle and extremely close distance is established using simulation software. Step 3: Based on the numerical model of top coal caving in the high-inclination and extremely close-distance section coal pillar, calculate the section coal pillar caving rate α1 and gangue content β1 at different caving step distances φ. According to the numerical simulation results, the relationship between caving step distance φ and caving rate α1 and gangue content β1 is obtained, and the optimal caving step distance φ' is determined; Step 4: Study different caving methods based on the optimal caving step distance φ' The coal pillar discharge rate α2 and gangue content β2 in the time zone are calculated based on the numerical simulation results to obtain the coal discharge method. Determine the optimal coal discharge method based on the relationship between discharge rate α2 and gangue content β2 Step 5: Optimal coal placement The top coal caving process parameters are designed in combination with actual engineering geological parameters.

2. The method for designing process parameters for top coal caving in a high-angle and extremely close-distance coal pillar according to claim 1 is characterized in that: In step 2, the gangue height H2 is 0 to 1.0 m.

3. The method for designing process parameters for top coal caving in a high-inclination and extremely close-distance coal pillar according to claim 1 is characterized in that: In step 2, the simulation software is PFC discrete element numerical simulation software.

4. The method for designing process parameters for top coal caving in a high-angle and extremely close-distance coal pillar according to claim 1 is characterized in that: In step 3, the release rates α1 and α2 are in the range of 80%-100%.

5. The method for designing process parameters for top coal caving in a high-inclination angle and extremely close-distance coal pillar according to claim 1 is characterized in that: In step 3, the range of the gangue content β1 and β2 is 0%-5%.

6. The method for designing process parameters for top coal caving in a high-angle and extremely close-distance coal pillar according to claim 1 is characterized in that: Step 3 is as follows: α1=M1 / M0 β1=M2 / (M1+M2) Where: M0 - total mass of coal in one coal placement step, kg; M1——total mass of coal in the discharge body, kg; M2——Total mass of gangue in the discharge body, kg; The optimal coal discharge step is to select the maximum discharge rate within 5% of the gangue content.

7. The method for designing process parameters for top coal caving in a high-inclination and extremely close-distance coal pillar according to claim 1 is characterized in that: Step 4 is as follows: α2=M1 / M0 β2=M2 / (M1+M2) Where: M0 - total mass of coal in one coal placement step, kg; M1——total mass of coal in the discharge body, kg; M2——Total mass of gangue in the discharge body, kg; The optimal coal discharge method is to select the maximum discharge rate within 5% of the gangue content.

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