Pig iron is a major dry bulk cargo, with global seaborne trade of approximately 10 to 15 million tonnes per year, principally moving from Brazilian, Russian, and Ukrainian producing regions to electric arc furnace and basic oxygen furnace steelmakers in the United States, the European Union, India, and Asia. Pig iron is the intermediate product of the iron blast furnace: molten iron that has been cast into ingots (historically into “pigs” — channels in a sand bed, hence the name) for transport and re-melting at downstream steel mills. The IMSBC Code regulates pig iron under a Group C schedule with no major chemical hazards.
Schedule structure
The IMSBC Code includes the following pig iron schedule entries:
- Pig iron: cast iron ingots, basic grade and special grades, in lump form. Group C (not liquefiable, no chemical hazard).
- Nodular pig iron: a specialty grade with magnesium content for ductile iron production. Group C.
- Granulated slag (related, but not pig iron): a different cargo handled separately.
Most marine pig iron trade is the basic grade used as feedstock for steelmaking, classified Group C and handled under standard bulk cargo procedures.
Cargo properties
Pig iron typically contains 92 to 96 per cent iron with 3 to 5 per cent carbon, 1 to 3 per cent silicon, and small percentages of manganese, phosphorus, and sulphur. The cargo is supplied as cast ingots of approximately 6 to 25 kilograms each, with dimensions of approximately 100 by 200 by 600 millimetres. Bulk density is approximately 4.0 to 5.0 tonnes per cubic metre, making pig iron one of the densest commercial bulk cargoes.
Stowage factor is approximately 0.20 to 0.25 cubic metres per tonne, which means a pig iron cargo occupies a small fraction of the vessel’s hold volume. Bulk carriers carrying pig iron are typically loaded to deadweight rather than to volumetric capacity, with the cargo concentrated near the tank top and significant void space remaining above. This loading pattern produces a low metacentric height and, if poorly distributed, can lead to dynamic stability issues that must be managed through cargo planning.
Cargo handling concerns
Pig iron is non-toxic, non-flammable, and presents no chemical hazards. The principal handling concerns are:
- Hold structural loading: the high cargo density concentrates load on the tank top and bilge structure. Hold structural strength must be verified before loading, and the cargo should be distributed evenly to avoid local overstress.
- Stability: the low stowage factor concentrates mass low in the hold, which produces favourable initial stability but can produce stiff roll behaviour in heavy weather. Bulk carriers carrying pig iron typically have good initial stability but rapid roll periods.
- Dust generation: pig iron generates moderate dust during loading, principally from broken corners and surface scale. Dust suppression is required at loading and discharge.
- Sharp edges: pig iron ingots have sharp cast edges that can damage hold paint coatings during loading. Pre-loading hold inspection should confirm paint integrity.
- Compatibility with steel: pig iron is benign to steel structure other than the mechanical wear from loading impacts.
Major exporters
Pig iron seaborne trade flows include:
- Brazil: the dominant exporter, with shipments through the ports of Vitória and Praia Mole. Brazilian pig iron is principally produced from charcoal-based mini blast furnaces in Minas Gerais and Maranhão.
- Russia: significant exports through Saint Petersburg, Murmansk, and Black Sea ports.
- Ukraine: until 2022 a major exporter through Mariupol, Yuzhny, and Odesa; volumes have collapsed since the Russian invasion.
- India: emerging exporter with shipments from Visakhapatnam.
- South Africa: exports through Durban and Richards Bay.
Major importers
Pig iron imports go principally to:
- United States (Gulf and East Coast steelmakers, particularly the EAF mini-mill sector that uses pig iron to balance scrap chemistry).
- European Union (Mediterranean and Baltic ports for southern and northern European steelmakers).
- Türkiye (Iskenderun, Aliağa).
- South Korea, Japan, and Taiwan (for specialised steel grades).
- India (despite being an exporter, some grades are imported for specific applications).
Loading and discharge
Loading is by grab-fitted shore cranes loading ingots in bulk into bulk carrier holds. Loading rates are slower than for fine bulk cargoes, typically 1,500 to 3,500 tonnes per hour per grab. The cargo does not self-trim and may require some bulldozer trimming for hatch closure, though the irregular shape of cast ingots provides natural angle of repose stability.
Discharge is similarly by grab and shore crane at receiving ports. The high density and irregular shape limit the throughput of pneumatic and continuous-unloader systems, which are not generally used for pig iron.