Saturday, 14 February 2015

Raw Materials for Steel - Part 2

Coal and coke

Coke is a fuel with few impurities and a high carbon content, usually made from coal. It is the solid carbonaceous material derived from destructive distillation of low-ash, low-sulfur bituminous coal. Cokes made from coal are grey, hard, and porous. While coke can be formed naturally, the commonly used form is man-made. The form known as petroleum coke, or pet coke, is derived from oil refinery coker units or other cracking processes.


As iron occurs only as iron oxides in the earth’s crust, the ores must be converted, or ‘reduced’, using carbon. The primary source of this carbon is coking coal. Coal is a key raw material in steel production.

Coal is primarily used as a solid fuel to produce electricity and heat through combustion. Coke, made by carburising coal (i.e. heating in the absence of oxygen at high temperatures), is the primary reducing agent of iron ore. Coke reduces iron ore to molten iron saturated with carbon, called hot metal.