The primary route involves three steps:

1. Ironmaking: Iron ore is reduced in the Blast Furnace (BF) using coke to produce molten pig iron (or use EAF with scrap steel/DRI).
2. Steelmaking (Conversion): The molten pig iron is charged into a Basic Oxygen Furnace (BOF), where pure oxygen is blown in to oxidize and remove excess carbon and impurities quickly.
3. Secondary Metallurgy: The resulting steel is transferred to a ladle for precise temperature and chemical composition adjustments. Finally, it's cast into solid forms (e.g., slabs or billets) through Continuous Casting before rolling.

Historically, Iron production dates back to before the Common Era (BCE), which occasionally yielded small amounts of steel. However, modern steelmaking enabling mass production was only established by the 19th-century Bessemer process.

Ironmaking and thus steelmaking evolved regionally because early processes were entirely dependent on local natural resources—specifically the quality of iron ore and the fuel source, initially charcoal.

For instance, Japan developed the Tatara ironmaking process, which uses iron sand to produce tamahagane—a specialized, high-purity steel essential for crafting exceptional Japanese swords. The West advanced via the Bloomery method, later transitioning to the Blast Furnace (BF), where coal/coke were plentiful.

Today’s focus is on advanced alloys like High-Tensile Steel (HSS) and tackling the severe CO₂ challenge, including a global shift away from the traditional Blast Furnace toward low-carbon methods, primarily the Electric Arc Furnace (EAF) utilizing scrap or green hydrogen-reduced iron. Decarbonization is the central mission of the global steel industry.