Emei mountain basalt group coal series interlayer mining gas treatment method

Abstract

The invention discloses a Emei mountain basalt group coal series interlayer mining gas treatment method. The method comprises the following steps that bedding drilling is constructed in a mining face transportation roadway and an air return roadway to control a stoping area to serve as a main area outburst prevention measure; constructing a crossing drill hole in a mining face transportation drainage roadway as an auxiliary measure to control an interlayer of a blank zone existing in a bedding drill hole; upward stepping type mechanical caving and drilling are constructed on the mining face transportation roadway to serve as an anti-reflection strengthening measure; and the local measure holes are constructed in each cycle in the mining face stoping process to serve as the final supplementary measure. According to the method, a stoping area is controlled by adopting a four-in-one all-dimensional gridding outburst prevention measure which takes bedding drilling as a main area outburst prevention measure, takes crossing drilling as an auxiliary measure, takes mechanical hole-making drilling as an anti-reflection strengthening measure and takes local advanced drilling as a supplementary measure, so that the aim of safe stoping is fulfilled.

Description

Technical Field

[0001] The invention belongs to the technical field of gas control in coal mining, and in particular relates to a method for gas control in coal-bearing interlayer mining of basalt group in Mount Emei. Background Art

[0002] The continental coal-bearing rock system within the coal mine field is mainly composed of basaltic volcanic rocks and volcanic clastic rocks intercalated with coal systems, which are called the coal-bearing interlayer of the Emeishan basalt group. The coal seam structure of this coal-bearing rock system is complex. The 113203 working face is located in the west wing of the first mining area of ​​Guizhou Songhe Coal Industry Development Co., Ltd. The 32# coal seam mined by the mining face is a special coal-bearing interlayer of the Emeishan basalt group. The working face is 79m away from the overlying 29-3# coal seam, which is an unminable coal seam and does not have the conditions for mining protective layers. The mining face has a mining strike length of 790m, an average mining dip length of 170m, and a mining reserve of 560,000t. There is no underlying coal seam. The basic top of the 32# coal seam is 34.4m, and the basalt capping index SI is 95%; the average thickness of the 32# coal seam is 2.8m; the average inclination is 28°; the original gas pressure of the coal seam is 2.84MPa; the original gas content of the coal seam is 12.28m 3 / t; coal seam permeability coefficient 0.07066m 2 / MPa2.d; the coal seam solidity coefficient is 0.52; the pseudo-top of the coal seam is a layer of 200-300mm thick kaolinite mudstone, which is softened by water; the direct bottom is bauxite.

[0003] According to the actual situation on site every day during excavation, the coal seam often contains 1-3 layers of coal, which gradually merge from west to east. The first layer is 0.85m-2.2m thick, with an average thickness of 1.5m; the second layer is 0.4m-0.75m thick, with an average thickness of 0.57m; the third layer is 0m-0.4m thick, with a smaller thickness, often a coal line, with unstable stratigraphic positions, and most of them are merged or pinched out.

[0004] The 32# coal seam mined by the 113203 working face has the characteristics of high gas, high pressure, high sealing index, high ground stress, low permeability and strong adsorption. It is difficult to meet the current situation of gas control work by adopting a single regional burst prevention measure. Summary of the invention

[0005] The purpose of the present invention is to provide a method for controlling gas in interlayer mining of coal measures in basalt group of Mount Emei, so as to solve the problem of safe mining of mining face.

[0006] The technical solution adopted by the present invention is a method for controlling gas in coal-bearing interlayer mining of basalt group in Mount Emei, comprising the following steps:

[0007] Step 1: Drill holes along the layers in the transportation tunnel and return air tunnel of the mining face to control the mining area as the main area anti-burst measures;

[0008] Step 2: Drill holes through the layers in the mining face transportation and drainage tunnel as an auxiliary measure to control the interlayer with blank zones in the layer drilling;

[0009] Step 3: Use walking-type mechanical hole drilling as a permeability enhancement measure in the construction of the mining face transportation tunnel;

[0010] Step 4: During the mining process, local measure holes are constructed in each cycle as the final supplementary measure.

[0011] Furthermore, in the above step 1, the drilling holes for the anti-blowout measures in the layer area are designed to be 130 holes in total, with a depth of 70m and a diameter of 120mm, and 130 holes in total, with a depth of 110m and a diameter of 120mm, in the return air lane, and 160m in depth and 120mm in diameter, in the transport lane.

[0012] Furthermore, in the above step 2, the holes for preventing burst in the interlayer area are designed in a group every 5 m in the transport and drainage tunnel, with 9 holes in each group, and a total of 158 groups with 1422 holes are designed.

[0013] Furthermore, in the above step three, mechanical hole-making and permeability-enhancing drilling is constructed in the area where the gangue is present in the transport tunnel of the mining face, and the drilling hole is located in the middle of the gangue.

[0014] Furthermore, the hole diameter of the above-mentioned mechanical hole drilling is 500mm, the hole step spacing is 10m, the hole length is 2m, and the hole drilling spacing is 10m.

[0015] Furthermore, in the above step 4, a local advance drilling hole with a depth of 12-20m is constructed every 3m in the mining face in each cycle to supplement the control and retain a 5m advance distance for mining in front, so as to verify the coal body in front of the mining face and further release the coal seam gas.

[0016] Compared with the prior art, the invention has the beneficial effect that the invention adopts the four-in-one all-round grid-based anti-burst measures, which are the main regional anti-burst measures, the interlayer drilling as the auxiliary measure, the mechanical hole-making drilling as the permeability enhancement measure, and the local advance drilling as the supplementary measure, to control the mining area, thereby achieving the purpose of safe mining. After the implementation of this technology, the extraction volume of hole-making drilling in the transportation lane of the coal-bearing interlayer mining face of the Emeishan basalt group increased by 87%; during the mining period, K 1 Maximum value 0.28mL / g·min 1 / 2 , effectively reduced by 66.7%; the average monthly mining was 70m, and the mining efficiency was increased by 65.74%; the maximum gas concentration in the working face during mining was 0.42%, and the goal of "zero over-limit, zero warning" was achieved during mining to ensure safe mining. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a three-dimensional schematic diagram of the implementation of gas control methods for coal-bearing interlayer mining in the basalt group of Mount Emei;

[0018] Figure 2 It is a realistic column chart of the local gangue on the working face;

[0019] Figure 3 Schematic diagram of the plan for drilling design of anti-burst measures in the layer-by-layer area of ​​the mining face;

[0020] Figure 4 Design profile of drilling holes for anti-burst measures in the interlayer area of ​​the mining face;

[0021] Figure 5 Schematic diagram of drilling and opening holes for mechanical cavitation and permeability enhancement measures;

[0022] Figure 6 Schematic diagram of drilling design for mechanical cavitation and permeability enhancement measures;

[0023] Figure 7 It is a dual-axis graph showing the comparison of the total extraction volume of common boreholes and cave-making borehole main pipes - the change of gas extraction volume;

[0024] Figure 8 Comparison of total extraction volume of common boreholes and cave-making borehole main pipes - filling diagram of changes in gas extraction volume;

[0025] Fig. 9 It is a comparison of the total extraction volume of common drilling and cave drilling main pipes - the curve of gas extraction volume change;

[0026] Fig.10 Comparison of total gas extraction volume between common borehole and cave-making borehole - 3D graph of gas extraction volume change;

[0027] Fig.11 It is a dual-axis graph of gas concentration comparison between common drilling and cave drilling - concentration change;

[0028] Fig.12 It is the comparison of gas concentration in the main pipe of common drilling and cavitation drilling - concentration change filling diagram;

[0029] Fig.13 It is the comparison of gas concentration in the main pipe of common drilling and hole-making drilling - 3D graph of concentration change;

[0030] Fig.14 It is the comparison of gas concentration in the main pipe of common drilling and hole-making drilling - 3D graph of concentration change;

[0031] Fig.15 It is the gas concentration variation curve during the mining face recovery period;

[0032] Fig.16 Verify the change curve of the area during the excavation and mining of the working face - the verification of the transport lane area;

[0033] Fig.17Verification curve of the area during the excavation and mining of the working face - verification of the return airway area;

[0034] Fig.18 Verify the change curve of the area during the excavation and mining of the working face - the verification of the cutting area;

[0035] Fig.19 It is the area verification change curve during working face excavation and mining - mining face area verification situation. DETAILED DESCRIPTION

[0036] The present invention will be further explained below in conjunction with the accompanying drawings to facilitate better understanding by those skilled in the art.

[0037] Example 1

[0038] The method for controlling gas in coal-bearing interlayer mining of basalt group in Mount Emei includes the following steps:

[0039] Step 1: Drill holes along the layers in the transportation tunnel and return air tunnel of the mining face to control the mining area as the main area anti-burst measures;

[0040] Step 2: Drill holes through the layers in the mining face transportation and drainage tunnel as an auxiliary measure to control the interlayer with blank zones in the layer drilling;

[0041] Step 3: Use walking-type mechanical hole drilling as a permeability enhancement measure in the construction of the mining face transportation tunnel;

[0042] Step 4: During the mining process, local measure holes are constructed in each cycle as the final supplementary measure.

[0043] The lithology of the top and bottom plates of the coal-bearing interlayers in the Emeishan basalt group is shown in Table 1.

[0044] Table 1 Lithology of the top and bottom plates of the coal-bearing interlayers in the Emeishan basalt group

[0045]

[0046]

[0047] The three-dimensional schematic diagram of the key technologies for gas control in coal-bearing interlayer mining in the basalt group of Mount Emei is shown in Figure 1 , the specific situation of local gangue in the working face is shown in Figure 2 .

[0048] For the 32# coal seam, under the conditions that the borehole diameter is not less than φ94mm and the extraction negative pressure is 14.2-18.8kPa, the extraction rate η is 45%, and the effective extraction radius for extraction times of 20, 30, 60, 90 and 120d are 2.49, 2.75, 3.04, 3.08 and 3.11m respectively. The drilling distance along the layer of the present invention is 6m, and the drilling distance through the layer is 5m, which at least meets the extraction radius requirement of 3.04m for 3 months.

[0049] According to the above requirements, the anti-burst measures drilling holes in the 113203 mining face along the layer area are designed every 6m from the return air lane, a total of 130 holes are designed, with a hole depth of 70m and a hole diameter of 120mm; the transportation lane is designed every 6m, a total of 130 holes are designed, with a hole depth of 110m and a hole diameter of 120mm; the anti-burst measures drilling holes in the 113203 mining face through the layer area are designed every 5m in the transportation and extraction lane, with 9 holes in each group, a total of 158 groups of 1422 holes are designed. See the schematic diagram of the drilling design. Figure 3-4 .

[0050] Since there are 1-2 layers of interlayered gangue in the 32# coal seam and a layer of 200-300mm kaolinite mudstone on the roof, the kaolinite mudstone will soften when it encounters water after the through-layer drilling hole passes through the coal seam, which will cause the borehole and screen pipe to be blocked, affecting the extraction effect. Therefore, after the anti-burst measures drilling construction in the layer and through-layer area is completed, in order to ensure that each layer of coal can be accurately controlled, according to the realistic sketch during excavation, mechanical cavitation and permeability enhancement drilling holes are constructed in the area with interlayered gangue in the 113203 transport lane. The drilling hole opening position is in the middle part of the interlayered gangue. The schematic diagram of the drilling hole opening for mechanical cavitation and permeability enhancement measures is shown in Figure 5 .

[0051] When the mechanical hole drilling radius is 500mm and the extraction negative pressure is 14.5Kpa, the extraction is carried out for 15 days, the effective extraction radius is 5m, and the extraction effective influence radius is 9m. The hole diameter of the present invention is 500mm, the hole step spacing is 10m, the hole length is 2m, and the hole drilling spacing is 10m, which meets the extraction radius of half a month 5m. In the K0+120m-79m section of the 113203 transport lane, a mechanical hole drilling hole is constructed every 10m. The drilling design of mechanical hole permeability enhancement measures is shown in Figure 6 , hole making parameters are shown in Table 2.

[0052] Table 2 Drilling design parameters for mechanical cavitation and permeability enhancement measures

[0053]

[0054] In order to prevent the gas in the hole created during the cutting process from suddenly rushing into the working face and causing gas exceeding the limit, a local advance drilling measure with a hole depth of 12-20m is constructed every 3m in the mining face in each cycle to supplement the control and retain a 5m advance distance in front for mining, to verify the coal body in front of the coal mining working face and further release the coal seam gas.

[0055] Comparison of extraction volume between common drilling and hole drilling

[0056] 245 common boreholes were constructed in the 113203 transport lane, and 67 mechanical hole-making holes were constructed. Under the same geological environment, the extraction volume of common boreholes was compared with that of hole-making boreholes. The total extraction volume of hole-making boreholes was 470,000 m3, which was calculated by automatic metering device. 3 , the total extraction volume of ordinary drilling is 60,000m 3 The total extraction volume of the hole-forming borehole is 87% higher than that of the ordinary borehole. The statistical table of the gas extraction volume of the ordinary borehole and the hole-forming borehole main pipe is shown in Table 3, and the comparison chart of the total extraction volume of the ordinary borehole and the hole-forming borehole main pipe is shown in Figure 7-10 .

[0057] Table 3 Statistics of total gas extraction volume from common boreholes and hole-making boreholes

[0058]

[0059]

[0060]

[0061] Comparison of gas concentration between ordinary drilling and hole drilling

[0062] The average gas concentration of the mechanical hole drilling main pipe in the 113203 transport lane is 32.46%, and the average gas concentration of the ordinary borehole is 7.07%. The extraction concentration of the hole drilling main pipe is 4.59 times higher than that of the ordinary borehole main pipe. The maximum gas concentration of the hole drilling main pipe is 52% and the minimum is 22%. The maximum gas concentration of the hole drilling single hole is 86% and the minimum is 20%, which is 68% higher than that of the ordinary borehole single hole. The comparison of gas concentration between ordinary borehole and hole drilling main pipe is shown in Figure 11-14 .

[0063] Investigation and analysis of gas concentration during mining

[0064] According to the 113203 mining face gas inspection report and monitoring data, a statistical analysis of the working face gas and return air flow gas is conducted every 7 days, and the maximum gas concentration in 7 days is selected for analysis and investigation. The statistical table of gas concentration during mining is shown in Table 4. The gas concentration change curve during mining is shown in Fig.15 .

[0065] Table 4 Statistics of gas concentration during mining

[0066]

[0067] According to the above data, the maximum gas concentration of the return air flow during mining of the 113203 mining face is 0.48%; the average gas concentration of the return air flow during mining is 0.3%; the maximum gas concentration of the working face is 0.42%; and the average gas concentration of the working face during mining is 0.26%.

[0068] Comparative analysis of regional verification during excavation and mining

[0069] According to the record sheet of "Guizhou Songhe Coal Industry Development Co., Ltd. Excavation (Mining) Working Face Forecast Report", the verification K of the 20 circulation transport lanes in front of the 113203 working face is obtained. 1 The maximum value is 0.42mL / g·min 1 / 2 , the minimum value is 0.18mL / g·min 1 / 2 , the average value is 0.3mL / g·min 1 / 2 ; Return air lane area verification K 1 The maximum value is 0.36mL / g·min 1 / 2 , the minimum value is 0.18mL / g·min 1 / 2 , the average value is 0.26mL / g·min 1 / 2 ; Eye cutting area verification K 1 The maximum value is 0.35mL / g·min 1 / 2 , the minimum value is 0.19mL / g·min 1 / 2 , the average value is 0.27mL / g·min 1 / 2 ; The maximum K1 value of the mining area is 0.28mL / g·min 1 / 2 , the minimum value is 0.14mL / g·min 1 / 2 , the average value is 0.2mL / g·min 1 / 2 The area verification during mining is obviously smaller than that during excavation. 1 Maximum drop: 0.28 mL / g·min 1 / 2 The maximum effective reduction rate was 66.7%, and the overall average reduction was 0.1 mL / g·min 1 / 2 The average decline rate is 33.3%. The statistical table of regional verification during excavation and mining is shown in Table 5, and the regional verification change curve during excavation and mining of the working face is shown in Figure 16-19 .

[0070] Table 5 Statistics of regional verification during excavation and mining

[0071]

[0072] Mining efficiency analysis

[0073] The geological conditions of the 123201 working face are similar to those of the 113203 working face. Both are working faces arranged in the interlayer of the coal-bearing system of the Emeishan basalt group. The strike length of the 123201 working face is 400m, the mineable dip length is 110m, the coal volume mined is 180,000t, the recovery time is 368d, the average monthly recovery is 32.6m, and the average daily recovery is 489.14t; the mineable strike length of the 113203 working face is 790m, the average mineable dip length is 170m, and the recoverable reserves are 560,000 tons. At present, the key technical section of gas control for mining the interlayer of the coal-bearing system of the Emeishan basalt group has been adopted, and 420m has been mined, and the coal volume mined is 299,800t. The recovery time is 210d, the average monthly recovery is 70m, and the average daily recovery is 1,428t, which is 938.86t more than the 123201 working face per day, and the recovery efficiency is improved by 65.74%.

[0074] In summary, we can know that:

[0075] 1) Under the same geological environment, the extraction volume of the hole-forming borehole and the ordinary borehole with the same extraction volume in the same extraction days were compared. The total extraction volume of the hole-forming borehole was 470,000 m 3 , the total extraction volume of ordinary drilling is 60,000m 3 The total extraction volume of the hole-making drilling is increased by 87% compared with the ordinary drilling.

[0076] 2) The average gas concentration of the mechanical hole drilling main pipe in the 113203 transport lane is 32.46%, and the average gas concentration of the ordinary borehole is 7.07%. The extraction concentration of the hole drilling main pipe is 4.59 times higher than that of the ordinary borehole main pipe.

[0077] 3) During the mining of the 113203 working face, the maximum gas concentration of the return air flow was 0.48%, and the maximum gas concentration of the working face was 0.42%, achieving the goal of zero gas exceeding the limit during mining, providing the necessary conditions for safe mining of the mining face.

[0078] 4) 113203 working face during mining period is K higher than during excavation period 1 Maximum drop: 0.28 mL / g·min 1 / 2 , effectively reduced by 66.7%, with an overall average decrease of 0.1 mL / g·min 1 / 2 , with an average decline rate of 33.3%.

[0079] 5) Under the same geological conditions, the 113203 working face recovered 633.44t more per day than the 123201 working face, and the recovery efficiency increased by 56.42%.

[0080] 6) Comparisons in mining efficiency, gas extraction concentration, gas extraction volume, return air flow gas concentration, etc., prove that the key technology for gas control in coal-bearing interlayer mining in the basalt group of Mount Emei is of great significance for gas control in basalt coal-bearing interlayers with high gas content, high pressure, high sealing index, high ground stress, low permeability, and strong adsorption. It makes up for the deficiencies in gas control in coal-bearing interlayer mining in the basalt group of Mount Emei and provides a theoretical basis for similar projects in the future.

[0081] The above-described embodiments are only for describing the preferred implementation of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit and principles of the present invention, various modifications and improvements made by those skilled in the art to the technical solution of the present invention should all fall within the scope of protection determined by the claims of the present invention.

Claims

1. A method for controlling gas in coal-bearing interlayer mining in the basalt group of Mount Emei, characterized in that: The following steps are involved: Step 1: Drill holes along the layers in the transportation tunnel and return air tunnel of the mining face to control the mining area as the main area anti-burst measures; Step 2: Drill holes through the layers in the mining face transportation and drainage tunnel as an auxiliary measure to control the interlayer with blank zones in the layer drilling; Step 3: Use walking-type mechanical hole drilling as a permeability enhancement measure in the construction of the mining face transportation tunnel; Step 4: During the mining process, local measure holes are constructed in each cycle as the final supplementary measure.

2. The method for gas control in coal-bearing interlayer mining of Emeishan basalt group according to claim 1 is characterized in that: In the step 1, one hole is designed every 6m in the return air lane for the anti-burst measures in the layer area, a total of 130 holes are designed, the hole depth is 70m, the hole diameter is 120mm, and one hole is designed every 6m in the transport lane, a total of 130 holes are designed, the hole depth is 110m, and the hole diameter is 120mm.

3. The method for gas control in coal-bearing interlayer mining of Emeishan basalt group according to claim 1, characterized in that: In the step 2, the holes for preventing burst in the interlayer area are designed in a group every 5 m in the transport and extraction tunnel, with 9 holes in each group, and a total of 158 groups with 1422 holes are designed.

4. The method for gas control in coal-bearing interlayer mining of Emeishan basalt group according to claim 1, characterized in that: The step three is to construct mechanical hole-making and permeability-enhancing drilling holes in the area where there is gangue in the mining face transport tunnel, and the drilling hole is located in the middle of the gangue.

5. The method for gas control in coal-bearing interlayer mining of Emeishan basalt group according to claim 4, characterized in that: The mechanical hole drilling diameter is 500mm, the hole step spacing is 10m, the hole length is 2m, and the hole drilling spacing is 10m.

6. The method for gas control in coal-bearing interlayer mining of Emeishan basalt group according to claim 1, characterized in that: In the step 4, a local advance drilling measure of 12-20m depth is constructed every 3m in the mining face in each cycle to supplement the control and retain 5m advance distance for mining in front, so as to verify the coal body in front of the coal mining working face and further release the coal seam gas.

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