Iron and steel scrap have been reused to produce new steel and cast iron in the steelmaking and foundry industry for more than 150 years, but the accumulation of tramp elements contained in steel scrap such as copper, tin, antimony, and arsenic is a major concern. This is primarily because these tramp elements are difficult to remove in conventional steelmaking processes. In particular, the presence of copper during the recycling of steel scrap can cause severe surface cracking during hot rolling (hot shortness), inhibit recrystallization during hot forming, and reduce ductility in deep drawing. For these reasons, considerable efforts have been made in recent decades to develop a technology that can remove copper from ferrous scraps[1-3].