4、,advanced andeconomicsystem.Theminewouldusethe methodofcentralcompond-likeventilation.Withtheincreaseofminingareas,themodalitywouldtransittothepartitiontypeventilationsystembydrainingoutmechanically.Firstofall,therequiredairvolumeofminewascalculated.Combiningthecalculationoftheresistancewhen the