Analysis on the problems and Countermeasures of tu

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Analysis on the problems and Countermeasures of tunneling ventilation during mine construction

tunneling ventilation is a ventilation safety measure and method taken to ensure that the operators of the tunneling face breathe fresh air and dilute the gas and harmful smoke and dust after blasting in the tunneling face. There are three types of tunneling ventilation in books: total air pressure ventilation, ejector ventilation and local fan ventilation

during the construction of new mines, full air pressure ventilation and ejector ventilation cannot be used, and local fan ventilation can only be used. There are three ways of local fan ventilation: Press in type, draw out type and mixed type. According to the provisions of the coal mine safety code, the driving of coal roadway, semi coal roadway and rock roadway with gas emission should adopt the pressure ventilation, and the extraction ventilation should not be used

after the construction of the auxiliary adit of Changling mine to the 1560 main roadway, the return air uphill, track uphill and main Adit in mining area 101 were excavated successively. Due to the long air supply distance, up to 1500 meters, there are too many excavation faces, up to four working faces. It is more and more difficult for the local fan to press into the ventilation through the air duct from the wellhead of the auxiliary adit, and the gas overrun of the return air flow is more and more frequent and serious. Try to use the conventional local fan centralized series ventilation to solve the ventilation problem of Changling mine excavation. Under the premise of unsatisfactory technical and economic effects, the project department has carried out some exploration under the guidance of the company, and the following is a shallow analysis

I. problem analysis

the construction of Changling coal mine of Yunnan Dongyuan Zhenxiong Coal Industry Co., Ltd. started in October 2003, and it has been three years so far. In the first two years of construction, due to only one team construction, single head tunneling, tunneling distance within 1000 meters, tunneling ventilation problems did not appear. After September, 2005, the original two tunneling teams of the project department concentrated on the mining construction in Changling. In March, 2006, the tunneling working faces changed from single head tunneling to two or three, with up to four working faces tunneling at the same time. The longest air supply distance of a single head reached 1600 meters, and the designed longest air supply distance was nearly 2800 meters. Therefore, the problem of tunneling ventilation in Changling mine construction is becoming more and more prominent, which has brought serious impact and safety threat to the mine construction. Through comprehensive analysis, there are the following problems:

1. With the acceleration of construction progress, the ventilation distance continues to increase, the ventilation resistance increases, the ventilation effect gradually decreases, and the wind pressure is insufficient

2. The gas emission after blasting in the heading face is large, and it takes a long time to blow out the gas. In the coal seam fracture is relatively developed, we should do a solid job in the energy efficiency improvement of Electromechanical, boiler, distribution transformer and other equipment, or the coal seam dislocation surface, near the fault, the gas concentration after blasting is above 4%

3. Due to the long air supply distance, there are many heading faces. The gas emission is large, resulting in the return air flow roadway under the roof 0 The UD zone of gas accumulation within 1m is characterized by over limit, up to 4%

4. The gas concentration in the total return air of the auxiliary adit exceeds the limit, up to 1.4%

5. The connecting roadway, roadway intersection, and return air flow are located in the depression of the roadway roof and the roadway top layer in the downwind section. The gas accumulation at the top of the roof crushing support exceeds the limit, up to more than 4% of the exchange of industry information

6. Due to abnormal power supply, single circuit power supply and frequent power failure, underground gas accumulation is caused. After the power supply is restored, the gas discharge time is long

II. Cause analysis

the excavation of Changling mine construction is the general name of aromatic heterocyclic polymers containing imide groups in the molecular main chain. The reasons for the above problems are various, and the main reasons are:

1. The lagging construction of Changling mine air shaft is one of the main reasons

after the establishment of the company in August 2004, according to the form of bidding, the air shaft construction of Changling mine was won the bid by the subordinate company of the 14th Metallurgical Corporation. Due to various reasons, the bid winner failed to enter the site for air shaft construction on schedule as required by the company. It was not until August, 2005 that the construction of the air shaft was started after the Zhenxiong mine construction project Department of Housuo coal mine concentrated on Changling, at least more than half a year later in the formation time of the return air system, which caused a problem that could not be fundamentally solved for the excavation ventilation of Changling mine construction. Finally, the head-on air supply distance and return air distance of each excavation were continuously extended, the ventilation resistance increased, and the head-on air volume was sufficient, The wind pressure of the fan cannot overcome the return air resistance

2. According to the geological data, Changling mining area is located between 13 and 14 geological exploration lines, belonging to the gas area, and the total amount of gas per ton of coal is 0 7m3/t。 That is to say, for a single heading, the maximum gas emission after blasting in the whole roadway can reach m3. However, the heading face is not operated, and the general gas emission is more than 4m3/min according to the gas concentration of the return air flow and the total air volume

3. Before the formation of the mine return air system, there were too many excavation heads. First, the underground gas emission increased; Second, the local fan is installed on the ground, and the air duct enters from the auxiliary adit for up to four times, reducing the return air section of the auxiliary adit and increasing the return air resistance

4. The fan capacity is small, the cross-section of the air duct is small, and the maintenance quality of the air duct is poor, which can not meet the needs of multi head long-distance air supply

5. Due to frequent power cuts and single circuit power supply, the planned power cuts and wind stops cannot be achieved

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