Method for reducing to metallic chromium the chromium oxide in slag from stainless steel processing

Abstract

The present invention relates to a method for reducing to metallic chromium the chromium oxide material found in slag formed in an electric arc furnace during the process of making stainless steel in that furnace. The chromium oxide content of the slag can be effectively reduced to a relatively low concentration by maintaining the slag in a liquid phase while at the same time blowing into the furnace via a carrier gas certain amounts of powdered aluminum dross. In particular, powdered aluminum dross can be blown into the furnace in amounts ranging from about 10 to 20 kg of dross per ton of molten steel in the furnace. Alternatively, powdered aluminum dross can be blown into the furnace in a thrown-in amount which satisfies the equation: 0.5≦[Thrown-In Al dross (ton)×100]/[Slag in Furnace (ton)×Cr2O3 (wt %)]≦1.0. Via such a method used during the stainless steel making process, the recovery of valuable chromium and the rate of chromium oxide reduction can be increased. Further, the cost of the stainless steel making process can be reduced by using relatively inexpensive powdered aluminum dross as the chromium oxide reducing agent instead of more expensive conventional reducing agents.

Dependencies are inferred from the claim text.