Specific design of outburst prevention in the hott

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Coal seam outburst prevention specific design and fault crossing safety technical measures

the transportation downhill in the second mining area of our mine has been excavated for 62.4 meters. A strike normal fault (fault strike 46, drop 5m) is encountered 6m in front of the head-on, which is the same fault as the track downhill. It is expected that the M16 coal seam will be opened 37m in front. The roadway adopts rectangular cross-section and bolt shotcreting support. When the roadway meets the M16 coal seam or passes the broken zone, the bolting shotcreting or anchor cable support method is adopted, and the net width of the roadway is 4.2m, The clear height is 2.6m. According to the relevant provisions of Article 62 of the provisions on the prevention and control of coal and gas outburst, combined with the actual situation of the mine, this special outburst prevention design is specially prepared

II. The situation of M16 coal seam in the coal uncovering area:

, the top and floor of M16 coal seam

the direct top of M16 coal seam is 1.5 m thick dark gray mudstone, the basic top is 7.5m thick siltstone, and the floor is gray black mudstone, 2.4m thick

, spontaneous combustion tendency of M16 coal seam

spontaneous combustion tendency of M16 coal seam belongs to three categories, namely, coal seams that are not easy to spontaneous combustion

, coal dust explosive

coal dust is non explosive

according to the mining conditions of other mining areas, there is no abnormal ground temperature in this area. It is a normal ground temperature mine

, and the gas in M16 coal seam

is a high gassy mine. According to the conclusion of the evaluation report on outburst elimination of M16 coal seam in gouzhai coal mine, the non M16 coal seam mined in the mine is a coal seam without coal and gas outburst

, geological comprehensive histogram

(1) fbdn-6 type one 230kw local ventilator and one 230kw standby colloidal flame retardant air duct with a diameter of 600mm are used for air supply when transporting downhill in mining area 2

(2) wind power lockout and gas power lockout are sensitive and reliable, and unplanned power outage is strictly prohibited

(3) strengthen ventilation management. Before blasting, the construction unit must conduct a comprehensive inspection of all ventilation facilities within the scope of influence. If they are damaged, they must be repaired and reinforced immediately to ensure that they are in good condition

(4) all ventilation facilities must be firm and intact, the air duct hanging is straight, and the distance from the head-on air duct outlet to the working face is not more than 5m. The joint shall be tight without air leakage, and sufficient air volume shall be ensured. Operation without wind or breeze is strictly prohibited

(5) when the air supply of local ventilator is abnormal or the standby ventilator cannot work normally, blasting is strictly prohibited for deterioration of performance

kj90na coal mine monitoring system is installed in this mine to monitor the gas concentration in each heading face and its return air flow in real time

1) T1 gas sensor is installed at the place ≤ 5m away from the working face in the transportation downhill roadway of mining area 2 to monitor the gas concentration in the air flow of the working face. When T1 ≥ 0.8%, it will alarm and power off; When T1 ≥ 0.8%, cut off all non intrinsically safe electrical equipment in the second mining area for transportation down the mountain, and evacuate all personnel in the roadway; Power on when T1 < 0.8%

2) T2 gas sensor is installed in the transportation downhill of mining area 2, 10 ~ 15m away from the return air outlet to monitor the gas concentration in the return air flow of the working face. When T2 ≥ 0.8%, alarm and power off, cut off the power supply of all non intrinsically safe electrical equipment in the transportation downhill of mining area 2, and evacuate all personnel in the roadway; Power on when T2 < 0.8%

3) the monitoring personnel should closely observe the gas changes in the roadway and conduct continuous monitoring. In case of abnormal gas emission, such as the maximum gas concentration (wave peak) and over limit time after blasting, they must immediately report to the mine dispatching room, the Outburst Prevention Director and the chief engineer; The ventilation director or the technical director reviews the monitoring curve every day, timely analyzes the daily gas monitoring data, finds out the causes in time if the gas monitoring data is abnormal, and indicates that the medical device components have outburst hazards, so decisive measures must be taken and reported to the chief engineer of the mine. The outburst risk of the heading face can be predicted according to its gas emission. The basic conditions are: the excavation process remains unchanged, the regular circular operation is adhered to, the air volume and air flow are stable, the return air flow gas sensor shall prevail, and the position between the sensor and the return air outlet remains unchanged. It is found that the gas changes greatly after blasting. The abnormal curve of gas concentration shall be printed by the monitor and submitted to the outburst prevention technician for analysis every day. The shift leaders, shift (Group) leaders, blasters, explosion-proof electricians, drilling foremen, etc. entering the working face must be equipped with portable instruments

(III) drainage system:

(1) the permanent gas drainage pump station on the ground of the mine has been installed and used. At present, there are two high and low negative pressure drainage pumps and auxiliary devices, water ring vacuum pump, model 2be (maximum drainage capacity 150m3/h), two high and low negative pressure main pipelines have been connected in place from the air shaft, and each branch pipeline is being installed to each working face under the mine. The diameter of the main pipeline is 400mm, and the diameter of the branch pipeline is 200mm. Now the gas pump has been in normal operation and put into use. In order to ensure underground gas drainage, it can be operated three shifts a day

(2) before the outburst prevention team constructs the pumping hole, install a pumping pipeline on the working face, and connect the pumping after the completion of the pumping hole construction

(IV) compressed air self rescue system:

the qualified compressed air self rescue system is installed for the transportation down the mountain in mining area 2 according to the regulations on outburst prevention. Each group can be used by more than 8 people, and the air supply volume of each breathing bag is not less than 0.1m3/min

IV. regional outburst prevention measures

1. Before the construction of pressure measuring (sampling) holes, the outburst prevention workers must prepare various sampling equipment and instruments in advance. After the drilling construction sees the coal, withdraw the drill and replace the core XC (6) xc (1) 0, take 10:1 lever drill pipe for sampling, and send the outburst prevention technician to the laboratory in time to test and determine the gas content of M16 coal seam in this area

2. During the construction of pressure measurement drilling, it must pass through the full thickness of M16 coal seam, and the drilling can be withdrawn only after 500mm into the roof of M16 coal seam

3. Pressure measurement can only be carried out after the hole is closed in time

4. After the pressure measuring borehole is sealed, a positive pressure gauge with a range of 1.5MPa must be installed within 16 ~ 24 hours

5. After installing the pressure gauge, the outburst prevention team will send special personnel to observe the gauge pressure once per shift and make records. The outburst prevention technician will collect data and draw the gas pressure curve in time

6. The time of pressure measurement at the pressure tap shall not be less than one week, and other gas drainage boreholes can be constructed after the completion of pressure measurement

sealing method of pressure tap:

1. Insert 4 points of iron pipe into the pressure tap, block the end of the iron pipe, weld a circular baffle plate (the diameter of the baffle plate is 70mm) at the end of 1.1m, drill a sieve hole within 1m, the diameter of the sieve hole is 4 ~ 6mm, and the total area of the sieve hole is greater than the sectional area of the iron pipe. Each 4-point iron pipe shall be made into 2 ~ 2.5m, and both ends of each pipe shall be processed with threads

2. Wrap cotton yarn on the baffle plate of the iron pipe, and then insert it into the pressure tap. The length of the inserted iron pipe is 1m longer than the drilling length of the opening section, and the exposed hole shall not be less than 200mm. When connecting the iron pipe to the pressure tap, wrap the tape around the screw thread to prevent air leakage at the iron pipe joint

3. First connect the iron pipe into the hole, put a wooden plug on the hole, then use a special cotton towel to stick the expansion agent into the pressure measuring hole, and then fill the remaining holes with cement slurry. After 16 ~ 24h, connect the pressure gauge

4. The pressure taps shall be sealed with yellow mud and cement mortar. Each pressure tap shall be sealed in time after construction. All pressure taps shall be sealed with metal pipes. The sealing length must not be less than 5m. The pressure measuring pipe shall not be blocked, and the hole shall be sealed tightly without gas leakage. After sealing the hole, wait 16 ~ 24 hours before connecting the pressure gauge, and then measure the gas pressure of M16 coal seam (the pressure gauge is installed by the communication and Prevention Department). The readings of the pressure gauge shall be observed and recorded by the tile inspector once a day, and the communication and prevention department shall be responsible for statistics and drawing the gas pressure curve

after pressure measurement: when the residual gas pressure is less than 0.74mpa, it indicates that there is no danger of outburst in the working face; When the gas pressure is ≥ 0.74mpa, it indicates that the working face has outburst risk. This design takes this as a method to predict the risk of regional coal and gas outburst

(II) regional outburst prevention measures

when the gas pressure of M16 coal seam is measured to be greater than 0.74mpa, there are incomparable characteristics of other materials in mining area 2. The gas drainage boreholes are constructed head-on in the working face of transportation downhill, and the pre drainage of M16 coal seam gas outburst prevention measures are taken. The diameter of the pre drainage M16 coal seam gas drainage hole is 75mm, the row spacing between the hole bottom is 2m, and the control range is: the roadway top, bottom and two sides are 12M, a total of 120 holes are constructed

attached figure 4: pre pumping drilling design drawing

pre pumping drilling parameter table

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