Process for directly reducing materials containing iron oxide in a rotary kiln in concurrent flow operation

Claim 2

IN A PROCESS FOR PRODUCING A SPONGE IRON PRODUCT WHEREIN THE FEED MATERIAL CONTAINING IRON OXIDE IS PREHEATED AND FED TO THE CHARGE END OF A ROTARY KILN WITH A SOLID CARBONACEOUS REDUCING AGENT TO CONSTITUTE THE KILN CHARGE THEREFOR, THE KILN CHARGE AND THE KILN ATMOSPHERE IS THEN REMOVED CONCURRENTLY IN THE KILN AT AN ELEVATED TEMPERATURE TO ACHIEVE A REDUCTION OF SAID FEED MATERIAL THEREIN, THE RESULTING REDUCED MATERIAL CONTAINING SPONGE IRON IS WITHDRAWN FROM THE DISCHARGE END OF THE ROTARY KILN, THE SPONGE IRON IS THEREAFTER COOLED AND SEPARATED THEREFROM AND THE EXHAUST GASES HAVING A TEMPERATURE ON THE ORDER OF ABOUT 1100*C ARE DISCHARGED FROM THE DISCHARGE END OF SAID KILN, THE IMPROVEMENT IN COMBINATION THEREWITH COMPRISING CONTACTING THE COOLED AND SEPARATED SPONGE IRON WITH AT LEAST A PORTION OF THE HOT EXHAUST GASES RECOVERED FROM THE DISCHARGE END OF SAID KILN UNDER NONOXIDIZING CONDITIONS ADJACENT THE DISCHARGE END OF AND OUTSIDE THE KILN TO PRODUCE A HEATED SPONGE IRON PRODUCT WHEREBY

Claim 3

In a process for producing a sponge iron product wherein the feed material containing iron oxide is preheated and fed to the charge end of a rotary kiln with a solid carbonaceous reducing agent to constitute the kiln charge therefor, the kiln charge and the kiln atmosphere is then moved concurrently in the kiln at an elevated temperature to achieve a reduction of said feed material therein, the resulting reduced material containing sponge iron is withdrawn from the discharge end of the rotary kiln, the sponge iron is thereafter cooled and separated therefrom and the exhaust gases having a temperature on the order of about 1100*C are discharged from the discharge end of said kiln, the improvement in combination therewith comprising contacting the cooled and separated sponge iron with at least a portion of the hot exhaust gases recovered from the discharge end of said kiln under non-oxidizing conditions adjacent the discharge end of and outside the kiln to produce a heated sponge iron product thereby cooling the exhaust gases to at least about 500*C, thereby permitting the ready transfer of said gases, transferring the cooled exhaust gases and using the transferred cooled exhaust gases to preheat said feed material containing iron oxide.

Claim 4

In a process for producing a sponge iron product wherein the feed material containing iron oxide is preheated and fed to the charge end of a rotary kiln with a solid carbonaceous reducing agent to constitute the kiln charge therefor, the kiln charge and the kiln atmosphere is then moved concurrently in the kiln at an elevated temperature to achieve a reduction of said feed material therein, the resulting reduced material containing sponge iron is withdrawn from the discharge end of the rotary kiln, the sponge iron is thereafter cooled and separated therefrom and the exhaust gases having a temperature on the order of about 1100*C are discharged from the discharge end of said kiln, the improvement in combination therewith comprising contacting the cooled and separated sponge iron with at least a portion of the hot exhaust gases recovered from the discharge end of said kiln under non-oxidizing conditions adjacent the discharge end of and outside the kiln to produce a heated sponge iron product thereby cooling the exhaust gases to at least about 500*C, thereby permitting the ready transfer of said gases, transferring the cooled exhaust gases and using the transferred cooled exhaust gases to preheat said feed material containing iron oxide.

Claim 5

A process in accordance with claim 1, which includes passing the cooled exhaust gases to an afterburning zone to be afterburned at the point where such gases are used to heat the kiln charge.

Claim 6

A process in accordance with claim 1, which includes feeding a kiln charge containing preheated feed material containing iron oxide to a first rotary kiln and feeding a kiln charge containing preheated feed material containing iron oxide to a second rotary kiln, the first and second rotary kilns being positioned such that the direction of flow of the kiln charge and the kiln atmoshphere in said first kiln is countercurrent to the direction of flow of the kiln charge and kiln atmosphere in said second kiln, and preheating the feed material of the kiln charge for the first kiln with the transferred cooled exhaust gases obtained from said second kiln after heating the cooled and separated sponge iron pellets from said second kiln and vice versa with respect to the feed material for the seCond kiln and the exhaust gases from the first kiln.

Claim 7

A process in accordance with claim 1 which includes contacting the reduced material obtained from the rotary kiln directly with water to cool same.

Claim 8

A process in accordance with claim 1, in which the reducing agent is a gas rich coal.

Claim 9

A process in accordance with claim 5, which includes blowing the gas rich coal into the charging end of the rotary kiln.