Direct reduced iron (DRI) is a major dry bulk cargo, with global seaborne trade of approximately 10 to 20 million tonnes per year, principally moving from Middle Eastern and South American producing regions to electric arc furnace steelmakers in southern Europe, Türkiye, and Asia. DRI is iron metal produced by reducing iron ore (typically pellets) with natural gas or hydrogen at temperatures below the melting point, yielding a porous metallic iron product with approximately 92 to 95 per cent metallic iron. The IMSBC Code regulates DRI shipments under three distinct schedule entries reflecting the different physical forms and corresponding hazard profiles.
Schedule structure
The IMSBC Code includes three DRI schedule entries:
- DRI (A) — Direct Reduced Iron (Briquettes, hot-moulded): hot-briquetted iron (HBI), pressed dense briquettes formed at temperatures above 650 degrees Celsius. Group B (chemical hazard, self-heating).
- DRI (B) — Direct Reduced Iron (Lumps, pellets, cold-moulded briquettes): cold DRI in lump or pellet form. Group B with significant self-heating risk.
- DRI (C) — Direct Reduced Iron (By-product fines): fine particulate by-product of DRI production. Group B with significant self-heating and dust hazards.
Each entry has distinct handling requirements. DRI (B) is the most hazardous due to large surface area, low compaction, and ready oxidation; DRI (A) (HBI) is the safest due to low surface area and dense compacted form.
Self-heating mechanism
Metallic iron oxidises spontaneously in the presence of oxygen and water:
3 Fe + 4 H2O -> Fe3O4 + 4 H2 (in elevated temperatures)
The reaction is exothermic. In compact DRI (HBI) the surface area is small and the heat is released slowly, allowing dissipation. In porous lump DRI (B) and especially in fine DRI (C), the surface area is much larger and oxidation is much faster, with potential for rapid temperature rise and hydrogen evolution. Hydrogen accumulation in the cargo hold atmosphere creates a flammable atmosphere and the elevated temperature accelerates further oxidation.
DRI (A) — Hot-briquetted iron (HBI)
HBI is the safest DRI form for marine carriage. The hot-pressing process produces dense briquettes with very low residual porosity, which limits oxidation rate. HBI typically does not require inert gas blanketing and is shipped in standard bulk carriers with normal ventilation provisions. The IMSBC schedule requires temperature monitoring and standard hold preparation.
Major HBI exporters include Venezuela (Comsigua, FMO), Trinidad and Tobago (Mittal Steel Point Lisas), and several Russian and Middle Eastern producers. HBI is the dominant marine-shipped DRI form and accounts for a majority of global seaborne DRI trade.
DRI (B) — Lump and pellet DRI
Cold lump and pellet DRI present substantially higher self-heating and hydrogen evolution risk and require strict handling:
- Inert gas blanketing: holds must be inerted before loading and maintained at oxygen concentration below approximately 5 per cent throughout the voyage. Inert gas (typically nitrogen) is supplied from shore systems at loading and maintained by shipboard generators or controlled venting.
- Dry conditions: cargo and holds must be dry. Water contact significantly accelerates the oxidation reaction.
- Temperature monitoring: continuous temperature measurement at multiple cargo points; temperature rises above 65 degrees Celsius warrant immediate response.
- Hydrogen monitoring: hold atmosphere monitored for hydrogen concentration; concentrations above 0.4 per cent (10 per cent of lower flammability limit) warrant ventilation and investigation.
- Avoidance of aluminium: aluminium components in the cargo space accelerate the reaction with water and are prohibited under IMSBC schedule provisions.
Several casualties involving cold DRI have occurred, including hold fires and hydrogen explosions, leading to progressive tightening of the IMSBC handling requirements.
DRI (C) — By-product fines
DRI by-product fines are the most hazardous DRI form. They are produced as a residual fraction of DRI production processes. The IMSBC Code restricts the carriage of DRI fines and requires inert gas blanketing, careful sampling, and explicit cargo declaration. Many shipowners and class societies decline to carry DRI fines due to the casualty risk; the volume of fines exported by sea is small.
Major routes
DRI seaborne trade flows include:
- Trinidad and Tobago (Point Lisas) export of HBI to Mexico, the United States, Türkiye, and Mediterranean steelmakers.
- Venezuela (Comsigua, formerly FMO) export of HBI to global markets.
- Russia (Lebedinsky GOK) export of HBI through Saint Petersburg.
- Saudi Arabia and UAE export of pelletised DRI to Türkiye, Egypt, and South Asia.
- Iran export of HBI under sanctions complications.
- Mexico (Ternium) coastal and short-sea HBI movements.
Loading and discharge
Loading is by shore conveyor and shiploader, with inert gas blanketing for DRI (B) and fines. Hold preparation requires comprehensive cleanliness, dryness, and pre-inerting where applicable. Discharge is by grab-fitted shore cranes, with attention to dust suppression and continued inert gas blanketing during discharge for DRI (B).