A distinguishing feature of steel as a material is the extraordinarily high degree to which it can be recycled. Additionally, the byproducts of steel manufacture, such as slag, also have a variety of different uses.
Slag, a byproduct of pig iron production, is an industrially produced artificial aggregate. A total of 80 percent of the blast furnace slag is processed in a granulating facility to produce ground granulated blast furnace slag. This slag is used in cement production and eliminates one of the baking processes, so reducing CO2 emissions. Other steel mill slag is used in road construction and as fertilizer. The lime extracted when softening drinking water to create process water can be used as agricultural fertilizer.