A mine consists of a single stoping section located at a depth of 2200 m accessed by a shaft. If a total of 8 rock drills each consuming 0.06 kg/s of air are used in the stoping section that is located a total distance of 2000m from the shaft bottom.
Determine the pressure and quantity requirements required of a compressor at surface to service the requirements of these rock drills.
It can be assumed that the active drilling section of the stope is located 450 m from the intake airway in which the compressed air main is located.
The maximum length of hose connected to the rock drills is 100m. It may also be assumed that the average atmospheric pressure at the surface is 100 kPa, underground the atmospheric pressure is 105 kPa and that steel pipe is used to convey the compressed air. There is no receiver in the system, thus assume the drills are working continuously.
The hoses used to supply the compressed air are 25 mm diameter and all other pipes in the system are of 152mm diameter.
The resistance factor for a 25 mm hose is and for a 152mm pipe are 3,000,000 m-5 and 200 m-5 respectively.