What measures should be taken to prevent and control gas in coal mining face?

In order to further improve the ability of coal mine gas prevention and control, and prevent gas accidents, combined with the methods, measures and management means of gas control in daily work, the "eight tricks" of gas control are summarized (one mine, one policy and one side, gas parameter determination, protective layer mining, fine drilling and drainage, evaluation of drainage standards, daily analysis of ventilation gas, outburst prevention forecast map and management of outburst prevention personnel). The specific interpretation is as follows:

The first measure: one mine, one policy and one side

(1) Purpose

"One mine, one policy and one side, one policy" means that Jinggong Coal Mine formulates the comprehensive gas control scheme of the level, mining area and mining face in advance according to the long-term plan of the mine and the annual mining succession plan, and coordinates the gas control methods, time and schedule in all regions throughout the year, so as to provide for gas control and mining succession.

(II) Implementation mode

1. In the fourth quarter of each year, the chief engineer of the mine takes the lead in formulating the gas control plan for each region in the next year's mining operation plan.

2. Coordinate the methods, time and schedule of gas control in each region, determine the "five indicators" of mine gas control (mining area of protective layer, engineering quantity of drilling, engineering quantity of gas control roadway, gas drainage amount and gas drainage rate), form "one mine, one policy, one side and one policy", and report it to the superior company for approval.

3. The technical director of the superior company of the coal mine organizes a special person to examine and approve the "one mine, one policy, one side, one policy" compiled by the coal mine, and the mine manager is responsible for its implementation.

(3) Requirements

1. The gas control schemes of each level, mining area and mining face include the selected outburst elimination measures, methods and time, measurement methods, effect inspection methods, gas control methods and daily advancement during mining of the working face.

2. the key to the compilation of "one mine, one policy, one side, one policy" lies in reasonable arrangement, orderly connection and strong operability.

3. the superior company should examine and approve the "one mine, one policy, one side, one policy" compiled by each mine.

4. the key to "one mine, one policy, one side, one policy" lies in its implementation, which is the responsibility of the mine manager, and the deputy mine managers of all disciplines implement it according to their division of labor. Sort out the implementation situation every month to see if the relevant tasks are completed as planned; Analyze and assess the implementation of "one side, one policy" every six months, and make appropriate adjustments according to the completion; Summarize once a year, sort out the existing problems, analyze the influencing factors in the implementation process, and put forward improvement measures to provide a basis for compiling the "one-sided policy" for next year.

the second measure: determination of gas parameters

(1) purpose

"determination of gas parameters" means that the chief engineer of the mine is responsible for organizing personnel or entrusting an intermediary agency to inspect and determine the evaluation indexes stipulated by the state, gas parameters of coal seams at various levels, mining areas and mining faces, so as to provide a basis for mine area prediction, selection of gas control methods, and evaluation of drainage standards.

(II) Implementation mode

1. According to national laws, regulations and standards, predict the critical value of the mine area, the prediction method, indicators and critical value of the working face; Technical parameters such as protective effect and scope of protective layer mining, drilling drainage radius, etc. The investigation and determination of gas parameters at various levels, mining areas and coal seams, such as original gas content, pressure, firmness coefficient, permeability coefficient, and attenuation coefficient of borehole 1 meters, shall be investigated regularly, and a determination plan shall be made, which shall be organized and implemented after being approved by the chief engineer of the mine.

2. Make a parameter determination scheme. Including the parameters to be measured, measurement position, target coal seam, drilling construction design, hole sealing method, parameter measurement method, observation requirements, etc.

3. according to the measured parameters, form a parameter measurement report, and fill the parameters in the gas geological map and outburst prevention prediction map.

(3) Requirements

1. Coal mines with ability can be determined by themselves, and coal mines without ability can be determined by intermediaries or superior companies.

2. The gas parameters must be determined for non-outburst coal seams mined in outburst mines and coal seams mined in high gas mines when the extension depth reaches or exceeds 5m or when new mining areas are developed. When measuring parameters, arrange as many measuring points as possible in the same unit.

3. Before uncovering coal in crosscut and eliminating outburst with strips, it shall be determined according to the detailed rules for prevention and control of coal and gas outburst.

The third measure: mining protective layer

(1) Purpose

"Mining protective layer" refers to selecting a layer of coal seam with no outburst danger or relatively weak outburst danger in the adjacent layer of outburst coal seam for priority mining. By mining protective layer, the gas occurrence mode in the protected layer is destroyed, the coal seam permeability is increased, and at the same time, the gas from the protected layer is pumped out to eliminate the outburst danger of the protected layer.

(II) Implementation mode

1. According to the scope of protection, determine the design of protective layer working face combined with the design of protected layer working face, formulate regional comprehensive outburst prevention measures, and implement them after being approved by the technical director of coal mining enterprises. Including roadway layout in protective layer working face, layout mode of pressure relief drainage drilling holes, selection of drainage system, control method of return air gas in protective layer working face, etc.

2. During mining, the pressure relief drilling hole shall be constructed according to the design, and the gas in the protected layer shall be drained.

3. after the mining of the protective layer working face, arrange the mining operation of the protected layer working face according to the stable time in the investigation report.

(3) Requirements

1. "Mining protective layer" is the most effective measure to eliminate outburst in the region, and it is also the only way out for outburst mines in the future. All outburst mines should be "guaranteed to the best, and guaranteed to be reported". When mining the protective layer, it is necessary to extract the pressure relief gas from the protected layer, otherwise it will be considered that the regional outburst prevention measures are not in place.

2. When mining protective layer, you can't leave coal pillars at will, and try your best to mine without coal pillars.

3. When the protective layer is mined for the first time in outburst mines, the protection effect and scope should be investigated.

4. if the maximum expansion deformation of the protected layer is more than 3‰, the inspection and investigation results can be applied to other areas with the same relationship between the protected layer and the protected layer.

5. when the interval between protective layer and protected layer, lithology and mining thickness of protective layer have changed greatly, the protection effect and effective protection range of protected layer should be investigated again.

6. in any of the following circumstances, the protection effect of each protected working face must be tested: (1) the protection effect and scope have not been actually investigated; (2) The maximum expansion deformation does not exceed 3‰; (3) The mining thickness of the protective layer is less than or equal to .5m; (four) the distance between the upper protective layer and the protected outburst coal seam is more than 5m or the distance between the lower protective layer and the protected outburst coal seam is more than 8m.

the fourth measure: drilling and gas drainage refinement

(1) purpose

"drilling and gas drainage refinement" refers to the refined management of drilling construction and gas drainage, improving the drilling construction accuracy and gas drainage effect, and further ensuring the implementation of outburst prevention measures.

(II) Implementation mode

1. According to the requirements of laws and regulations and the standardization standards of safety production, and referring to the management regulations of other coal enterprises, formulate the detailed management regulations of drilling and drainage that meet the requirements of this mine, and clarify the requirements of technical data and on-site management.

2. drilling and drainage shall be constructed, managed and accepted according to the standard requirements from the design to the end of the project, so as to ensure that the construction is in place according to the design and improve the management level and drainage effect.

(3) Requirements

1. According to the approved regional outburst prevention measures, the coal mine formulates the special design for drilling construction and drainage. Including drilling site construction, drilling hole arrangement mode, hole opening position, hole diameter, drilling angle, expected coal point, final hole position, coal seam anti-permeability measures, construction rig model, slag discharge mode, blowout preventer installation, construction requirements, drilling trajectory determination, hole sealing requirements, data recording, video monitoring, drilling acceptance and other construction requirements, observation of parameters such as drilling pumping, negative pressure concentration, location of automatic metering device for pumping and orifice flowmeter.

2. Before drilling construction, if the geological conditions are unclear, first construct two positioning drilling holes to determine the coal seam conditions, and then modify the original design parameters.

3. after measuring the drilling trajectory, it is necessary to fill the hole in time when it is found that the drilling deviation is large.

4. The drilling construction and drainage shall be managed according to the requirements of safety standardization, including on-site civilized production and listing management.

the fifth measure: evaluation of drainage reaching the standard

(1) objective

"evaluation of drainage reaching the standard" refers to the evaluation of drainage effect. The standard of drainage is the license, and the evaluation is the most important part. It can be determined whether the mining operation can be carried out through the evaluation, which also provides the basis for gas control.

(II) Implementation mode

1. Led by the chief engineer of the mine, the regional outburst prevention and drainage effect is judged according to the Interim Provisions on Gas Drainage Standards in Coal Mines.

2. The evaluation of drainage standard is divided into basic condition evaluation and drainage effect evaluation. Before the evaluation, collect all the data of the construction of the drainage project and evaluate it item by item. Define the basic conditions and the effective control range of drainage drilling respectively (for bedding drilling, the effective control range of drilling is determined according to the control edge line in the length direction of drilling, the connecting line between the two outermost drilling holes and the position of drilling opening. The control edge line in the drilling length direction is the connecting line of the effective hole depth points of the drilling, and the final hole point of the shorter hole in the adjacent effective drilling is taken as the effective hole depth point of the adjacent drilling; For cross-layer drilling, the effective control range of drilling takes the range delineated by the connecting line between the coal-seeing points of adjacent effective edge holes), the evaluation of hole distribution uniformity of drainage holes (the difference coefficient of pre-drainage time is less than 3% as an evaluation unit), the determination of evaluation index of drainage gas effect (residual gas content, pressure and desorption amount) and the evaluation of drainage effect (the wind speed is not more than 4m/s and the gas concentration is not more than 1%).

(3) Requirements

1. The residual gas content of coal seam should be calculated first before the effect inspection of regional outburst prevention measures, and the actual inspection can only be carried out when the calculated value is lower than the critical value.

2. when dynamic phenomena such as blowhole occur during inspection, it is deemed that the drainage is not up to standard.

3. When the gas mainly comes from this coal seam, the desorption amount should be judged, and when the gas comes from the adjacent layer, the drainage rate should be judged, and the mine drainage rate should also meet the requirements.

4. Check that the drilling layout meets the following requirements. (1) When using the outburst prevention measures of coal seam gas in the pre-pumping section and the outburst prevention measures of coal seam gas in the pre-pumping mining area, if the width of the section (the distance between the two sides of the mining roadway plus the control range of the outer side of the mining roadway) or the width of the mining area does not exceed 12m, at least two inspection and testing points are arranged at intervals of 3 ~ 5 m along the advancing direction of the coal mining face; Otherwise, at least three inspection and testing points shall be arranged at intervals of 3 ~ 5m along the advancing direction of the coal mining face, and the distance between the inspection and testing points and the two sides of the mining roadway shall be more than 2m；; (2) When pre-pumping coal seam gas in coal roadway strips by drilling holes through layers, at least one inspection and testing point shall be arranged at intervals of 3-5m along the coal roadway strips; (3) When pre-pumping the coal seam gas in the exposed area of the roadway with cross-layer drilling, at least four inspection and test points shall be arranged, which are located in the middle of the roadway and on the upper and both sides outside the contour line of the roadway, and at least one inspection and test point located in the lower part of the contour line of the roadway shall be added when uncovering the coal from the roof of the coal seam to test the effect of the outburst prevention measures; (4) When pre-pumping coal seam gas in coal roadway strip with bedding borehole, at least one measuring point shall be arranged at intervals of 2 ~ 3m along the coal roadway strip, and each evaluation area shall not be less than five inspection and testing points; (5) Each inspection and testing point shall be arranged in the position where the borehole density is small, the hole spacing is large and the pre-drainage time is short, and it shall be as far away from the pre-drainage boreholes as possible or as equidistant as possible from the surrounding pre-drainage boreholes, so as to avoid the discharge range of the mining roadway and the pre-drainage lead distance of the working face. Appropriately increase inspection and testing points in areas with complex geological structures. The actual location of the inspection test point and the actual measured parameters shall be marked on the gas drainage borehole completion drawing.

the sixth measure: daily analysis of ventilation and gas

(1) objective

"daily analysis of ventilation and gas" refers to the daily analysis of ventilation system, gas emission, geology of mining face, implementation of outburst prevention indicators and measures, gas extraction system, fire prevention system, safety monitoring system and implementation of opinions of previous daily analysis meetings, so as to grasp the daily changes of mine gas control work through daily analysis.

(II) Implementation mode

1. At the beginning of each month, the chief engineer of the mine will convene relevant units (departments) to determine the key areas and analysis contents of ventilation and gas management in that month according to the continuous changes of mining and production. Low-gas mines should analyze the ventilation and gas daily in key areas, high-gas and outburst mines.

2. Organize a daily analysis meeting every day, and each member department will report their daily analysis contents according to the division of responsibilities, investigate the possible hidden dangers of ventilation and gas in the mine, analyze the reasons, formulate measures, and arrange the responsible units to rectify the problems identified.

3. Participants: chief engineer of mine, ventilation manager and deputy chief engineer of ventilation (of the above three, one must preside over the meeting), and there must be more than one technician and management personnel in gas control, technology, geological survey, safety management, ventilation, outburst prevention (extraction), safety monitoring, underground production operation and other auxiliary departments that need to attend.

4. The daily analysis meeting shall form meeting minutes and establish ledgers. The contents of the record shall include: time, place, participants, report content, cause analysis, measures taken and work arrangement, implementation of daily analysis opinions on ventilation and gas in the previous period and rectification.

(3) Requirements

1. When the methane concentration in any place fluctuates at or above .2% on duty or in the upper and lower shifts, it must be analyzed, the reasons must be found out, and measures must be taken, and it should be explained in the daily analysis record of ventilation and gas.

2. In case of gas overrun, the general prevention and safety management departments of the superior company should check the reasons on site, formulate preventive measures and supervise their implementation.