Analysis on problems and countermeasures of tunneling ventilation during mine construction
During the construction of the new mine, full air pressure ventilation and ejector ventilation are unusable and can only be used for local fan ventilation. There are three types of local fan ventilation: push-in type, draw-out type and mixed type. Press the "Coal Mine Safety Regulations" provides that coal roadway, gas emission and coal roadway half of the rock heading should be forced ventilation, exhaust ventilation should not be used.
After the construction of the Changling Mine deputy flat road to the 1560 main road, the 101 mining area was opened and the wind returned to the mountain, the track up the mountain and the main level. Due to the long supply distance, the maximum length is 1500 meters, and the excavation work surface is arranged too much, up to four working faces. It is more and more difficult for the local fan to be ventilated from the auxiliary Pingshuo well through the air duct, and the gas flow overrun is more frequent and serious. Under the premise of technical and economic effects, the project department conducted some explorations under the guidance of the company under the premise of unsatisfactory technical and economic effects, and conducted a shallow analysis.
First, the problem analysis
The Changling Mine of Yunnan Dongyuan Zhenxiong Coal Industry Co., Ltd. started construction in October 2003 and has been in operation for three years. In the first two years of construction, there was only one team construction, single heading, and the tunneling distance was within 1000 meters. The tunneling problem was not revealed. After September 2005, the original two excavation teams of the project department concentrated on Changling for mine construction. In March 2006, the heading face was changed from single heading to two or three, and up to four working faces were simultaneously excavated. The longest wind supply distance is 1600 meters, and the longest design wind supply distance is nearly 2800 meters. Therefore, the ventilation problem of the mining construction of Changling Mine has become more and more prominent, which has brought serious impacts and safety threats to the construction of the mine. Comprehensive analysis, the main problems are as follows:
1. The ventilation distance increases with the acceleration of the construction schedule, the ventilation resistance increases, the ventilation effect gradually decreases, and the wind pressure is insufficient.
2. The amount of gas emission after the cannon is larger, and the time required to blow out the gas is longer. In the coal seam fissure development area or the coal seam displacement surface, near the fault, the gas concentration behind the gun is more than 4%.
3. Due to the long supply distance, there are many excavation working faces. The gas emission is large, which causes the gas accumulation in the range of 0.5-0.1m below the roof to exceed the limit of up to 4%.
4. The gas concentration of the wind in the total return air of the deputy Pingyi exceeded the limit, reaching a maximum of 1.4%.
5. Contact the lane, the roadway is at the intersection, the return air flow is in the roof of the downwind road section and the top of the roadway, and the roof gas accumulation on the roof of the roof is over 4%.
6, due to power supply is not normal, single-loop power supply, frequent power outages on the network caused underground gas accumulation, after the restoration of power supply, the discharge of gas for a long time.
Second, the cause analysis
There are many reasons for the above problems in the tunneling of Changling Mine Mine Construction. The main reasons are:
1. The construction lag of Changling Mine wind shaft is one of the main reasons.
After the establishment of the company in August 2004, according to the bidding form, the Changling Mine wind shaft construction was won by the company of the 14th Metallurgical Company. Due to various reasons, the winning bidder did not enter the site on time to carry out the construction of the wind shaft. It was not until August 2005 that the post-coal mine construction project of Housuo Coal Mine started construction of wind shafts after the concentration of Changling, at least half a year after the formation of the return air system, causing ventilation for the construction of Changling Mine. The problem that cannot be solved fundamentally has finally formed that the heading air supply distance and the return air distance are continuously extended, the ventilation resistance is increased, and the head wind volume is sufficient, and the wind pressure of the fan cannot overcome the return air resistance.
2. According to the geological data, the Changling mining area is located between the geological exploration line 13#-14#, belonging to the gas area, and the total amount of coal per ton is 0.11-19.7m3/t. That is to say, a single excavation heads for the head, and the gas can be pumped up to 230-240m3. The excavation working face does not work. According to the gas flow concentration and total air volume, the normal gas emission is above 4m3/min.
3. Before the formation of the return air system of the mine, the excavation head is arranged too much. First, the amount of gas emission from the underground is increased. Second, the local fan is installed on the ground, and the air duct enters from the sub-flat, and at most enters the four-inch air duct. The secondary flat return section has increased the return air resistance.
4, the fan capacity is small, the wind tunnel section is small, the air cylinder maintenance quality is poor, can not meet the long-distance long-distance air supply needs.
5, frequent online power outages, but also a single-loop power supply, can not achieve planned power outages and winds.
Third, the countermeasure analysis
The ventilation problem of Changling Mine construction excavation has become more and more prominent with the acceleration of the excavation progress and the increase of the excavation head. The safety threat of gas overrun is becoming more and more serious, and the production impact is getting bigger and bigger. In response to this situation, the company's leaders and the project department jointly studied and adopted the following countermeasures:
1. To fundamentally solve the problems of tunneling and ventilation in Changling Mine, it is necessary to speed up the construction progress of Changling Mine No. 1 wind shaft and 101 mining area return wind uphill, and form a return air system as soon as possible. To this end, on December 28, 2005, the company's relevant leadership and project department meeting decided to take eight measures to speed up the construction progress of Changling No. 1 wind shaft and 101 mining area returning to the wind.
First, the project department strengthened its strength and organized it to speed up the construction of the 1706-meter roadway of No. 1 wind shaft and 101 wind-up mountain. From January 1, 2006, it strived to penetrate on August 31, 2006.
Article 2: If the geological conditions change during the excavation process, the rock tunneling exceeds 500 meters, and the penetration time is postponed until September 30, 2006.
Article 3: In order to speed up the progress, small section excavation is adopted, the net height is guaranteed to be 2.5 meters, the net width is guaranteed to be 2.9 meters, and the ch5 coal seam is drilled according to the mid-line. After the penetration, the brushing, undercover and Chengxiang are carried out.
Article 4: During the construction process, the bolts are guaranteed to be laid according to the design requirements, and the anchors are filled and the leaks are checked and accepted.
Article 5: During the construction process, the fault section and the roof broken section shall be temporarily supported by wooden brackets, and then the concrete support shall be carried out after the penetration.
Article 6: The company pre-allocates 65% of the project funds to the project department on a monthly basis according to the budget.
Article VII, the through-construction will be completed on time, and the company will increase the unit price by 28.5 yuan per meter roadway as an incentive for continuous construction.
Article 8: After the project is completed, the secondary lanes and supports shall be carried out after the monthly acceptance. The remaining construction cost is paid per meter in the settlement unit price.
Through the above measures, the construction progress of the No. 1 wind shaft and the 101 mining area returning to the wind is greatly accelerated, but due to the geological conditions and design, the No. 1 wind shaft is nearly 180 meters away from the Fengshimen, and is still in the loose landslide of the ancient landslide. Protection; 101 mining area returning to the wind before and after the mountain again and again large faults, three local roof treatment, as of the end of July, No. 1 wind well and 101 mining area back wind up the mountain is still about 580 meters through, is expected to be formed at the end of November 2006 Return air system.
2. Replace the high power fan and the Φ800mm air cylinder. In March, for the wind pressure is insufficient, the gas flow exceeds the limit, and the gas accumulation in the range of 0.5-0.1m under the roof of the return flow roadway has been replaced by a 2×22KW bureau fan, 2×15KW bureau fan, and Φ500mm air duct. Replace it with a total of 2300 meters of Φ800mm air duct, increase the total wind pressure of the mine supply, total air volume, and overcome the resistance of the return airway. The gas flow back to the wind and the over-limitation of the gas have been alleviated, so that the production of the heading face can be carried out normally.
3. For the depression at the top of the roadway, the local gas accumulation at the top of the frame support section is over-limit, strengthen the detection, and periodically insert the air duct and the air duct to wash, effectively controlling the gas concentration below 1%.
4. Increase the maintenance cost of the air duct to ensure the effective air volume at the head. In April, in the case of insufficient ventilation personnel, the project department assigned some air duct maintenance to the management of the tunnel. The monthly ventilation cost was increased by 1,500 yuan, and the three teams increased the company's ventilation cost by 4,500 yuan per month.
5. Before the wind shaft No. 1 and the 101 mining area return to the wind, the local ventilation system is modified to form a local area ventilation system, shortening the local fan pressure into the supply air distance, shortening the return air passage length and reducing the return air resistance. It is necessary to completely solve the problem of gas accumulation overruns such as the deputy main Pingyi, the 101 mining area returning to the upper reaches of the mountain, the 101 mining area track up the mountain 1560 main road and the connecting lane. There are two before and after the local ventilation system renovation plan.
Solution 1, the first consideration is the hybrid ventilation. That is, a set of dampers are set in the 1560 main road between the returning wind uphill in the 101 mining area and the uphill mountain in the 101 mining area. The local fan presses the fresh air into the driving face through the ground, and returns to the 1560 main damper through the working face. The installed negative pressure air duct is extracted by the ground air blower.
This program has the following shortcomings after actual implementation, and is finally denied. First, the negative pressure air cylinder is Φ1000mm, the inner lining steel ring, the steel ring spacing is 500mm, the third Φ800mm air cylinder has been installed in the sub-flat, and the Φ500mm air cylinder is no longer able to install a Φ1000mm negative. Pressure. Even if a negative pressure air duct is installed, the transport and effective return air section cannot be guaranteed in the sub-flat. Second, due to the narrow industrial plaza, there is no suitable place to install the exhaust fan.
Scheme 2: The main flat design of Changling Mine is 670 meters long, and it is divided into two sections, east and west. By the middle of July, the east and west sections of the main flat are only 65 meters away. After the company's leadership and the project department jointly researched, after the main section of the main section of the Pingyi was used, the deputy Pingyi was used to enter the wind, and the main Pingyi returned to the wind, and the “Renovation Plan for the Local and Subtropical Local Ventilation System of Changling Mine†was formulated. The ventilation scheme of 1 is modified to the ventilation mode of Figure 2 (see attached figure). The original fan will be installed in the position of the sub-level Pingjing wellhead. The fresh wind will be moved from the four hurricane cylinders to the digging planes. The wind will be moved back to the ground by the heads of the heads. In the mining area, the position of the windward gate and the track are on the mountain. The fresh air is headed by the deputy Pingyi→1560 alley.
The wind is from the head to the contact lane → the upper section of the 101 mining area → the main level → the ground.
5.1, related parameters and fan selection results
1. The length of the inlet tunnel is 1,140 meters, including: 500 meters for the deputy plane, 100 meters for the 1560 lane, 500 meters for the track, and 40 meters for the corridor.
2. The length of the return airway is 1,100 meters, including: 500 meters for the main level, 100 meters for the small contact road, and 500 meters for the lower part of the 101.
3, through the wind speed, air volume gas abnormal flooding and ordinary gushing amount to calculate the four working faces need 1000m3 / min wind.
4. The total height difference between the main and auxiliary Pingshuo wellheads is 4 meters.
5, the deputy Pingyi S net = 11.3m2, the main flat ç¡S net = 7.9m2, 1:60 alley S net = 11.3m2, the track uphill S net = 8m2, the return wind up the mountain S net = 10m2.
6. Calculate the ventilation resistance: maximum resistance 383Pa, minimum resistance 318Pa.
7. The calculated air volume of the exhaust fan is 1102m3/min.
8. According to the above parameters, the draft fan is selected as:
Model BK60-NO10
Motor power 30KW
Air volume Q=1100-760m3/min
Wind pressure P=1200-290Pa static pressure efficiency is 80%
5.2 Relevant requirements and safeguards
1. The exhaust fan is installed in the main flat sluice, the sealed wall is built, and the second damper is installed.
2. The exhaust fan is separated from the outside by a wall to ensure the safe diffusion of the exhausted air.
3. In case of power failure, the main flat damper door is opened, so that the main and auxiliary flat rafts form natural ventilation and reduce the range of gas accumulation.
4. Strengthen the use management of the damper seal to ensure the stability of the system.
After the renovation of the main and sub-flat ventilation systems, the system was basically stable from May to July, and the ventilation capacity satisfies the needs of current safe production. The problem of the over-limit of the gas flow back to the working face of each excavation face has been fundamentally reversed. After the local ventilation system was rebuilt, the 101 wind recovery section of the mining area shortened the supply wind distance by 600 meters. The belt conveyor conveyor in the mining area shortened the supply wind distance by 600 meters. The 101 mining area track uphill shortened the supply wind distance by 1000 meters.
6. The online power supply is coordinated by the company and the local area. Now the local network and the provincial network are connected to the network, and the power supply has improved.
Fourth, a little experience in the construction of new mines
1. New mines in high gas mines, especially in Changling Mine, the design length of the wind shaft to the sub-level raft is about 280 meters. In order to solve the problem of long-distance tunneling ventilation, the wind shaft and the main shaft should be arranged at the same time. After the formation of the ventilation system in the mining area, other tunnel construction will be arranged.
2. During the construction of high gas mines, in order to reduce the problem of gas overrun caused by insufficient ventilation capacity, at most three tunneling faces can be arranged at the same time.
3. During the construction of the mine, the main and auxiliary wells shall be constructed at the same time. When the local fan-inlet ventilation cannot meet the requirements of safe production, refer to the “Reconstruction Plan for the Main Ventilation System of the Main and Sub-levels of Changling Mine†to implement partial negative pressure ventilation. .
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