Removing impurities from steel scrap using air and chlorine mixtures

The presence of zinc in steel scrap causes difficulties in the production of steel and leads to environmental problems. This article describes a separation route using air and chlorine mixtures to remove zinc from steel scrap prior to melting in an electric arc furnace. Thermodynamics shows that zinc chloride is more stable than its oxide, while the reverse is true for iron. Through the use of an air and chlorine mixture (10:1), zinc is selectively removed from steel at 800°C in the laboratory. The reaction products characterized by various analytical techniques confirm the thermodynamic analysis. This process offers an attractive solution to obtain clean steel scrap and useful chemicals. Editor’s Note: A hypertext-enhanced version of this article appears on the JOM web site at www.tms.org/pubs/journals/JOM/9908/Tee-9908.html. For more information, contact J.K.S. Tee, University of Cambridge, Department of Materials Science and Metallurgy, Pembroke Street, Cambridge CB2 3QZ, United Kingdom; telephone 44 (0)1223 334360; fax 44 (0)1223 334567; e-mail ksjt2@hermes.cam.ac.uk.