The steelmaking process starts with the processing of iron ore. The rock containing iron ore is ground and the ore is extracted using magnetic rollers. Fine-grained iron ore is processed into coarse-grained clumps for use in the blast furnace. Coal is cleaned of impurities in a coke furnace, yielding an almost pure form of carbon. A mixture of iron ore and coal is then heated in a blast furnace to produce molten iron, or pig iron, from which steel is made.

Molten steel from the furnaces passes through continuous casters and is formed into slabs, blooms and billets. These primary steel products are transformed into a wide range of finished steel products through hot and cold rolling processes. Slabs are rolled into flat products; blooms are shaped into girders, beams and other structural shapes; and billets are formed into bars and rods.

Smelting is a form of extractive metallurgy; its main use is to produce a base metal from its ore. This includes production of silver, iron,copper and other base metals from their ores. Smelting makes use of heat and a chemical reducing agent to decompose the ore, driving off other elements as gases or slag and leaving just the metal base behind. The reducing agent is commonly a source of carbon such ascoke, or in earlier times charcoal. The carbon (or carbon monoxide derived from it) removes oxygen from the ore, leaving behind the elemental metal. The carbon is thus oxidized in two stages, producing first carbon monoxide and then carbon dioxide. As most ores are impure, it is often necessary to use flux, such as limestone, to remove the accompanying rock gangue as slag.

 Pig iron has a very high carbon content, typically 3.5–4.5%,[1] along with silica and other constituents of dross, which makes it very brittle and not useful directly as a material except for limited applications.