United States Steel Corporation

Stephen Waslo

Jerome Feinman

John L Howell

Joseph E McGreal

Edward J Nemeth

A process for producing a low-sulfur content hot reducing gas stream comprising (a) contacting a sulfur bearing hot reducing gas stream with a desulfurizing agent comprising a desulfurizing fixed bed of solid particles comprising calcium oxide to thereby produce a low-sulfur content hot reducing gas stream and a calcium sulfide composition, then (b) contacting said calcium sulfide composition with an oxidizing gas composed of CO.sub.2, H.sub.2 O and O.sub.2 to thereby convert the sulfide of the composition to a regenerated calcium oxide, and sulfur dioxide and then (c) reusing the regenerated calcium oxide in step (a) to desulfurize a hot reducing gas, and further involving the improvement comprising avoiding the formation of calcium sulfate when regenerating said calcium sulfide composition by means of (a) a separate clean-up bed after the desulfurizing bed of step (a) to assure complete conversion of the calcium oxide to calcium sulfide in the desulfurizing bed, or (b) passing the oxidizing gas through the partially sulfided desulfurizing bed from a direction which minimizes the contact of any sulfur dioxide formed in the regeneration step with any unsulfided calcium oxide.

Desulfurizing of reducing gas stream using a recycle calcium oxide system

Passivation of sponge iron by a mild reoxidation thereof is effected by contact, at a temperature of 200.degree. to 600.degree. F, with a gaseous atmosphere consisting essentially of 25 to 80% H.sub.2, 15 to 70% CO and 0.5% to 4.0% O.sub.2 for a time in excess of about 1 hour. The passivation atmosphere may be produced by dilution of a free-oxygen-containing gas with conventional reducing gases. Therefore, the process is particularly amenable to the in-line passivation of hot reduced pellets i.e. wherein passivation may be effected directly within the lower portion of a shaft furnace.

Process for the passivation of sponge iron utilizing reducing gases

A method is disclosed for reducing iron ore wherein spent reducing gas may be used as fuel in a reformer, and a portion of the reformer product is used as cooling gas in the bottom portion of the shaft furnace to lower the temperature of the reduced product in a controlled manner whereby the product is rendered more stable and thereby more suitable for storage and shipment.

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Penn Hills Township, PA, United States of America

Stephen Waslo