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