introducing alumina into the tank at {HEAD ~ a slow rate CL} which is from {TAIL ~ 15 to 50%} below the normal rate of alumina consumption CN 
is from
introducing alumina into the tank at { HEAD ~ a slow rate CL } which is from { TAIL ~ 15 to 50 % } below the normal rate of alumina consumption CN
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH