Reducing the Zinc Emissions by Upgrading of Steel Scraps Quality

Résumé

The steel production is one of the major sources of heavy metals emissions to the environment. There are several possibilities for prevention and minimization of these pollutants. Emission reduction measures focus on add-on technologies and process modifications (including operating control). The prevention of the raw materials use that may have an unacceptable environmental impact in steel manufacture is important in achieving good environmental performance. A preventive measure specified by steel making BAT is the lowering the zinc-content of scraps. A way to make this possible is to treat these scraps before their charging in the furnace (BOF or EAF). In this paper a method for removing zinc surface layers of galvanized steel scraps is studied. The principle of separation is based on the difference in vapor pressures and stabilities with the formation of zinc and iron chlorides. A series of thermal experiments was carried out in an atmosphere of gaseous HCl. As result of the treatment applied on galvanized steel samples, zinc surface layers were removed and steel scraps remain unattacked.