Continuous oxygen steelmaking with copper-, tin-, and zinc-contaminated scrap

ISSN： 1543-1916

Source： Metallurgical and Materials Transactions B, Vol.35, Iss.4, 2004-08, pp. : 663-674

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Abstract

In the context of a new zero-gas-emission process for continuous oxygen steelmaking, desorption of copper, tin, and zinc from liquid scrap are modeled. Additive diffusional-resistance concepts show that zinc elimination at atmospheric pressure is entirely straightforward. For copper and tin, a reduced pressure (2.5 mbar) and a relatively high temperature (1780 °C) are preferred. Sulfur must be added above the stoichiometric requirements to volatilize tin sulfide. Copper elimination by physical desorption is completely predictable, but with tin, interfacial chemical kinetics may possibly exert an influence. Based on exclusive transport control and the currently available pumping capacity for vacuum degassing steel, the engineering feasibility of refining continuously melted steel scrap is established. Dimensions are estimated for producing 2 Mtpa of steel with a scrap-to-virgin iron ratio of 3 to 1. Electrical conductive heating is required to raise the liquid-scrap temperature toward the limits imposed by current refractories. With the proposed new technology, copper, tin, and zinc are all recovered as by-product metals. Pretreatment of steel scrap is not advocated, other than simple physical segregation at the source.