A compartment is provided within the kiln for selectively introducing {HEAD ~ a reducing agent} into {TAIL ~ the chamber} 
into
A compartment is provided within the kiln for selectively introducing { HEAD ~ a reducing agent } into { TAIL ~ the chamber }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL