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1 Mine return air network communicates with the surface, it is difficult to close the maintenance;
2 There are a large number of mines with thin ground and high permeability in the wells or caving areas of the ground mining area;
3 uranium- bearing mines with mineral rock fissures;
4 Mines in low pressure areas above 3000m above sea ​​level .
Withdraw ventilation is recommended in the following cases:
1 The mine return air network communicates with the surface less, and it is easy to maintain the airtightness;
2 The ore body is buried deep, and the empty area is easy to be sealed or collapsed, and the mine with weak gas permeability is weak;
3 Mines and surrounding rocks have mines that are at risk of spontaneous combustion.
Mixed ventilation should be used in the following cases:
1 need to communicate with the ground network of more than wind, and large air leakage into the return air Netease in a closed mine;
2 mines that are prone to spontaneous combustion due to air leakage in the caving area;
3 The ventilation line is long and the resistance is large. It is impossible or uneconomical to use the partition ventilation and multi-well parallel ventilation technology.
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