Steel: Extraction

Two routes: the blast furnace or the scrap furnace

Steel is made, not mined. The integrated route smelts iron ore with coke in a blast furnace to make pig iron, then blows oxygen through it to cut its carbon. The scrap route melts old steel, sometimes with direct-reduced iron, in an electric arc furnace. Each tonne of steel recycled saves about 1.1 tonnes of iron ore, 0.6 tonne of coking coal and 0.05 tonne of limestone (USGS). Alloying metals such as manganese, chromium, nickel, molybdenum and niobium add strength or corrosion resistance. Nearly all US steel, 99.7%, is now continuously cast.

Steel is made by two main routes. The integrated route reduces iron ore with coke in a blast furnace to make molten pig iron, then blows oxygen through it in a basic oxygen furnace to burn off carbon. It is large, capital-heavy and coal-intensive, and dominates in China, Japan, Korea and India. The scrap route melts old steel, often with direct-reduced iron, in electric arc furnaces. It is smaller, cheaper to build and much lower in energy and carbon, and dominates in the US and Turkey. India adds a third: coal-based DRI kilns feeding induction and arc furnaces, which lets small producers make steel without coking coal. Hydrogen-based DRI is the main decarbonisation hope.

Methods compared

How each method works

Sinter, pellets and lump are charged with coke into a blast furnace that produces liquid iron at about 4% carbon. In the BOF, a supersonic oxygen jet cuts carbon to steel levels in under an hour, with up to about a fifth scrap as coolant. Steel is then cast and rolled on site.

Makes high-purity flat steel at huge scale from virgin ore; emits about 1.8-2.0 t CO2/t in the West and up to 3.5 t in India, and needs coking coal.

Shredded and heavy melting scrap, sometimes with pig iron or DRI, is melted by graphite electrodes, refined in the ladle and cast into billets or thin slabs. Mini-mills often roll rebar, merchant bars or coil next door.

Capital cost only 15-20% of a BF-BOF plant and 0.4-1.1 t CO2/t; limited by scrap quality and supply and power cost.

Pellets or lump are reduced in solid state by natural gas (shaft furnaces such as MIDREX) or by non-coking coal in rotary kilns, then melted with scrap. India runs many coal-based kilns feeding induction furnaces; the Middle East runs gas-based shafts.

Avoids coking coal and allows hydrogen in future; gas DRI emits 1.4-2.0 t CO2/t but Indian coal DRI up to 3.3 t.

Who does it: global

Who does it: India

India is the world's second-largest steel producer, at about 160 Mt of raw steel and 98 Mt of pig iron in 2025 (USGS), and the main growth market as Chinese demand falls. It leans on blast furnaces and coal-based DRI, so its CO2 per tonne is among the highest. Ministry of Steel data: crude steel 152.2 Mt in FY2025 from 200 Mt of capacity, made 41% in BOFs, 21% in EAFs and 38% in induction furnaces; sponge iron 55.8 Mt, 84% coal-based. National Steel Policy 2017 targets 300 Mt of capacity by 2030-31. Per capita use was only 64 kg in 2013 against 570 kg in China (Smil).