United States Steel Corporation

Skf Steel Engineering Ab

Skf Plasma Technologies Ab

Jerome Feinman

Sven O Santen

Joseph E McGreal

Sune Eriksson

John L Howell

Stephen Waslo

Edward J Nemeth

A method for melting iron and steel scrap wherein scrap is fed through a shaft furnace countercurrent to a reducing gas. The reducing gas is formed by passing air through a plasma generator and injecting coal and/or hydrocarbon into the hot air so that the ratio (CO.sub.2 +H.sub.2 O)/(CO.sub.2 +H.sub.2 O+CO+H.sub.2) of the resulting gas becomes less than 0.2. The energy needed for melting is supplied as sensible heat of the reducing gas. The energy for preheating the scrap is supplied by introducing oxygen containing gas into the preheating zone at a plurality of positions along the flow path of the reducing gas to provide stepwise combustion of the reducing gas. The introduction of the oxygen containing gas at said plurality of positions is balanced to keep the gas reducing to the metal scrap at scrap temperatures above 1000.degree. C., and preferably even above 800.degree. C. The invention also comprises an apparatus for carrying the method into effect, and the apparatus comprises means corresponding to the various method features above.

Method and apparatus for melting iron and steel scrap

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

Finely powdered oxidde ore is introduced (at 17) in a reactor (11), possibly together with slag-formers, and treated in three zones in the reactor. The material is preheated and possibly melted in an upper, oxidizing zone by the combustion of carbon monoxide and hydrogen gas from the middle zone below with a gas containing oxygen. In a middle zone consisting of a slag bath, the preheated and possibly melted oxide material at least partially reduced by the simultaneous injection of carbonaceous material and/or material containing hydrocarbon (15, 16) and thermal energy supplied primarily by means of gas heated in a plasma generator (14). Finally, the material is caused to sink into a lower zone at the bottom of the reactor, from where it is tapped intermittently, together with the slag, through a tapping aperture (19).

Method of manufacturing metals and/or generating slag

A process and apparatus for producing a low sulfur content, hot reducing gas by desulfurizing hot reducing gas by contacting the sulfur-bearing hot reducing gas with a bed of a particulate calcium oxide desulfurizing agent to thereby produce a product gas stream and a byproduct calcium sulfide composition, and then recovering sulfur from the calcium sulfide composition by contacting the calcium sulfide composition with hot liquid water at a temperature and corresponding pressure sufficient to maintain steam in the system and to thereby convert the sulfide to calcium hydroxide and hydrogen sulfide and to produce a liquid water stream containing sulfur, and then combining the sulfur-containing water stream with a fresh water stream and recycling this water stream for contacting the calcium sulfide composition. Preferably water vapor produced in the contacting step is condensed and returned to the system in the final stage of contacting the calcium sulfide composition with hot liquid water.

Growing community of inventors

Grand Junction, CO, United States of America

Jerome Feinman