METHOD OF PRODUCING VANADIUM SLAG AND NATURALLY VANADIUM-ALLOYED STEEL Russian patent published in 1998 - IPC

FIELD: ferrous metallurgy. SUBSTANCE: invention deals with conversion of vanadium cast iron into vanadium slag and semiproduct in oxygen converter followed by converting semiproduct into steel in another converter. As cooling agents in vanadium cast iron conversion process, 10-120-mm fractions of dross and metal waste are used, which are added into converter after cast iron is charged and/or during blowing, metal waste intake being 30-80 kg and dross 15-40 kg per 1 t of cast iron. In the semiproduct conversion stage, cooling agents are metal scrap, metal waste, and/or dross. Slag-forming materials are added in the course of blowing after ignition of fusion in portions ensuring optimum rate of slag formation and metal heating. Metal is blown until carbon content at least 0.07 wt % is reached. Carbonization, vanadium alloying, and partial deoxidation of metal are accomplished by liquid vanadium cast iron, whose amount is determined from content of carbon in final steel using proposed formula. In order to optimize heat balance, metal scrap is additionally heated. Heating may be performed by feeding carbon- containing fuel together with scrap or onto scrap to be burnt with oxygen. As carbon-containing fuel, coke and/or undersized coke, coals, carbon lining and electrode fragments, crude oil, mazut, and natural gas can be used. To prevent slopping of metal from ladle, vanadium cast iron designed for metal carbonization, deoxidation, and alloying may be supplemented with 20-50% of deoxidizing agents required for smelting. Final melting of metal is accomplished on "furnace-ladle" installation. Using proposed technology enables processing vanadium cast irons in oxygen converters via duplex process utilizing metal scrap and/or metal waste up to 20%. Naturally alloyed steel thus produced contains 0.05-0.15& vanadium. EFFECT: reduced smelting time, extended product mix, reduced flux and ferroalloy intake, and increased installation productivity on the whole. 9 cl, 1 tbl