Development of a new Dust and Slag Treatment Technology (Construction and Operation of DSM Process)

Recently it is very important to decrease the amount of steelmaking wastes such as slag, dust and used refractories. As for the slag and used refractories, several technologies have been developed to recycle them as road construction materials, refining flux, reformed brick materials and so on. On the other hand EAF dust is not used profitably because of its composition and properties. Since the disposal cost of EAF dust in presumed to be more expensive in the future, a new dust treatment technology is strongly desired. Daido Steel has developed a new dust and slag treatment process called "DSM" (DSM : Daido Special Method of Dust Slag Melting). DSM is a process in which EAF dust is melted together with reduced slag with a special burner to get oxidized slag and concentrate zinc in EAF dust into the secondary dust. The oxidized slag obtained in DSM process is used as road construction materials, and the secondary dust is utilized as raw materials of zinc smelting. In short, EAF dust is completely reused with DSM. Daido Steel constructed DSM furnace at Chita Plant and started its operation in 1996. In this paper, the outline of DSM process is described, and some operational results are also reported herein.