National Minerals Information Center

Iron and Steel Slag Statistics and Information

Slags are nonmetallic byproducts of many metallurgical operations and consist primarily of calcium, magnesium, and aluminum silicates in various combinations.   Iron and steel slags are coproducts of iron and steel manufacturing.    In the production of iron, the blast furnace is charged with iron ore, fluxing agents, usually limestone and dolomite, and coke as fuel and the reducing agent.   The iron ore is a mixture of iron oxides, silica, and alumina.   From this and the added fluxing agents molten slag and iron are formed.  The physical characteristics such as density, porosity, and particle size, are affected by the cooling rates and chemical composition.   Depending on the cooling method, three types of iron slag are produced— air cooled, expanded, and granulated— that have different types of applications.


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Cris Candice Tuck

Mineral Commodity Specialist, Physical Scientist
National Minerals Information Center
Phone: 703-648-4912