A method and apparatus for reducing a feed material in a rotary hearth furnace

摘要

A rotary hearth furnace for reducing a feed material. The rotary hearth furnace (10) includes a rotating hearth (12) disposed in an enclosure and mounted for rotary movement. The enclosure includes an annular inner wall (14), an annular outer wall (16) and a roof (18). The enclosure is sealed to the hearth and divided into a plurality of zones including at least a loading zone (28), a process zone (24) and a discharge zone (22). The furnace further includes a plurality of burners (20) positioned in at least the outer wall of the enclosure to provide a controlled temperature within the rotary hearth furnace and a flue (30) positioned within the reduction zone of the furnace between the preheat zone (26) and the discharge zone (22) to exhaust combustion gases from the burners and gases resulting from the processing of the feed material. Said flue contains space for combustion and settling of the unburned particulates. A water spray quench reduces the temperature of the furnace off-gas so that subsequent combustion by the introduction of air or oxygen does not produce significant nitrogen oxides.