RESEARCH ACTIVITIES ON REMOVAL OF RESIDUAL ELEMENTS FROM STEEL SCRAP IN JAPAN

This paper outlines the activities of 2 Japanese research groups (Comm ittee for Removing Residual Elements from Steel Scrap of the Iron and Steel Institute of Japan and Scrap Recycle Technology Project of the J apan Research and Development Center for Metals (JRCM)) on the removal of copper and tin from steel scrap. To use all of steel scrap generat ed as feed material for steel production in 2010, copper will have to be removed from steel scrap by about 55% on average. Of the methods fe asible in principle for removing copper from steel scrap, a combinatio n of conventional shredding followed by automatic sorting and treatmen t of the copper-rich fraction by cryogenic shredding and magnetic sepa ration, aluminum bath immersion or wet treatment with ammonia, are exp ected to find early commercial applications. The necessary average rem oval ratio of tin is about 30%. To accomplish this target without addi ng another process, 2 methods were found to be promising. One method i s to oxidize and remove tin when the steel scrap is preheated, and the other is to vaporize tin as stannous sulfur (SnS) when the steel scra p is melted by oxygen and coke or coal. A total scrap melting system w ith the addition of copper and tin removal from steel scrap or molten steel will be evaluated in the JRCM project. (C) Munksgaard, 1998.