Importance

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Abstract

In a process for hardening oxidizable green iron ore pellets in a vertical shaft furnace, said process comprising passing the pellets through the furnace wherein said pellets are heated by contact with hot combustion gases and air, the furnace having a zone which is downstream of the introduction of the combustion gases, said zone having an average temperature in the range of about 1100.degree. F. to about 2200.degree. F., the improvement comprising directing a plurality of oxygen streams at the pellets passing through the periphery of said zone in such a manner that (a) each stream penetrates into the furnace about one to about six inches measured from the inside surface of the furnace wall along a line perpendicular to the theoretical vertical axis of the furnace; (b) the velocity of each stream is sufficient to substantially prevent the stream from flowing up the furnace wall; (c) the points of introduction of the streams are on the inside surface of the furnace wall located in the zone; and (d) any theoretical vertical line, which is parallel to the theoretical vertical axis of the furnace and along which line any point of introduction is located, is no more than about 12 inches from any other such theoretical line along which any other point of introduction is located.

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First Claim