It would be feasible to use {HEAD ~ almost any conventional classifying means} which permits {TAIL ~ material} of less than a certain size to pass through while blocking large material 
permits
It would be feasible to use { HEAD ~ almost any conventional classifying means } which permits { TAIL ~ material } of less than a certain size to pass through while blocking large material
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH