The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 30, 1997
Filed:
Dec. 14, 1995
David M Kundrat, Cincinnati, OH (US);
Allan M Smillie, Middletown, OH (US);
Richard C Sussman, West Chester, OH (US);
Armco Inc., Middletown, OH (US);
Abstract
A three-stage process for obtaining metallic Cr units insitu during the production of stainless steel. Raw chromite ore or a concentrate produced from chromite ore is mixed with a carbonaceous reductant and slagging agents are added to an iron bath (24) for smelting and refining in a refining reactor (10). During the first stage, partially metallized chromite is smelted by carbon in the reactor that is top-and bottom-blown with oxygen and oxygen-containing gases respectively to produce a chromium alloy bath having a carbon content well below saturation. In the second stage, the alloy bath is decarburized by being bottom stirred with the oxygen-containing gas to the final bath carbon specification. In the third stage, the alloy bath is reduced by a metalloid reductant such as silicon or aluminum and again bottom stirred but with a non-oxidizing gas to achieve a high chromium yield. The reactor includes a top lance (18) extending through a throat (14) with a lower portion (20) of the lance extending to a point just above the bath and means (22) such as a tuyere or porous plug mounted at or near a bottom (16) and extending through a refractory lining (12) for stirring the iron bath containing dissolved carbon. Lance (18) includes a central passage (34) for injecting a compact, focused jet oxygen gas (30) that can penetrate through a slag layer (26) for decarburization of the iron bath and an outer passage (32) for discharging an oxygen gas (28) above the bath for post-combustion of CO to CO.sub.2. Passage (32) includes a plurality of evenly spaced annular diverging nozzles (33). The lance also includes a pair of concentric conduits (36) and (38) for conducting a coolant.