Select the proper size and number of cyclones for a rod/ball mill circuit given the following conditions:

o New feed to the rod mill = 250 tph

o Discharge from both mills join together at cyclone feed sump and is pumped to cyclones.

o Cyclone overflow is at 60% minus 74 microns @ 40% solids by wt.

o Cyclone underflow @75% solids by weight is ball mill feed

o Specific gravity od solids is 2.9

o Estimated circulating load is 225%

o Assume pressure drop @50kPa