Deterrents to the Recycling of Ferrous Scrap from Urban Refuse
SourceAlthough predictions indicate that the demand for ferrous scrap will shortly exceed supplies, resistance exits to the use of the ferrous fraction of urban refuse. Reasons for this resistance include lack of reliable supplies and the deleterious effects of contaminants, such as aluminum, copper, and tin. Aluminum can cause slag foaming in the BOF and pinholes in cast iron, while copper and tin promote a pearlitic structure thereby increasing ferrous alloy strength while decreasing ductility. With proper processing these problems can be overcome. Detinning of unburned cans removes the tin and aluminum (because they have not been incinerated they do not contain copper). Densification of the detinned steel produces a premium furnace feed. Alternatively, the unprocessed scrap can be used in amounts ranging up to 10 percent of the cast iron or steel produced.