Petroleum coke (petcoke) is a major dry bulk cargo, with global seaborne trade of approximately 35 to 45 million tonnes per year. The cargo is the solid carbon residue from petroleum refining (specifically delayed coking) and serves two principal end-uses: as a high-energy fuel for cement kilns, power plants, and steel mill blast furnaces (fuel-grade petcoke) and as a feedstock for carbon anodes in aluminium smelting (calcined petroleum coke). The IMSBC Code regulates petcoke shipments under a Group B schedule reflecting self-heating and dust ignition hazards.
Schedule structure
The IMSBC Code includes the following petroleum coke schedule entries:
- Petroleum coke (calcined): heat-treated petcoke for aluminium anode use. Group B with self-heating and dust hazards but lower volatile content.
- Petroleum coke (uncalcined): green petcoke for fuel use. Group B with higher volatile content and elevated self-heating risk compared to calcined.
The shipper must declare the type and the relevant fuel-grade or anode-grade specification on the cargo declaration.
Cargo properties
Petroleum coke is supplied as black granular material with particle size typically 5 to 50 millimetres for fuel-grade and finer for calcined anode-grade. Bulk density is approximately 0.7 to 0.9 tonnes per cubic metre, with stowage factor of approximately 1.1 to 1.4 cubic metres per tonne. Calorific value is approximately 32 to 35 megajoules per kilogram, comparable to or higher than bituminous coal.
The product contains typically 0.5 to 7 per cent sulphur depending on the source crude oil; high-sulphur petcoke is generally restricted to industrial fuel use, while lower-sulphur grades supply aluminium anode markets and cleaner industrial fuels.
Hazards
Petcoke presents three principal marine carriage hazards:
- Self-heating: oxidation of the carbon and residual hydrocarbon content is exothermic. Heat accumulation in compacted petcoke cargoes can lead to spontaneous combustion. The IMSBC Code requires temperature and CO monitoring during voyage, similar to coal cargoes.
- Dust generation and ignition: petcoke dust is fine, abrasive, and combustible in air. Loading and discharge operations must control dust accumulation and ignition sources.
- Methane release: lower than bituminous coal but not negligible, particularly for fresh green petcoke that has been recently produced. Hold atmosphere monitoring for methane is required.
Calcined petcoke (heat-treated to 1,200 to 1,400 degrees Celsius) has lower volatile content and presents reduced self-heating and methane risks compared to uncalcined.
Major routes
Petcoke seaborne trade flows include:
- United States to Asia, Latin America, and Mediterranean: the largest export, with Gulf and West Coast refineries supplying global markets through Houston, Long Beach, and other terminals.
- Saudi Arabia, Kuwait, UAE to Asia: significant Middle Eastern petcoke export from major refineries.
- India and China: both export and import depending on grade and fuel-versus-anode use.
- Mexico and Venezuela: Latin American supply to North American and European markets.
China and India are the dominant importers, supplying cement and aluminium industries. India’s imports are particularly large for the cement sector, where petcoke is a competitive fuel against coal.
Loading and discharge
Loading is by shore conveyor and shiploader with dust suppression. Hold preparation requires standard cleanliness and bilge clearance. Hot work permits are suspended throughout loading, voyage, and discharge.
Voyage handling includes daily CO monitoring, methane monitoring particularly during the early voyage, and surface ventilation as required. Hold temperature monitoring is performed where instrumentation is available.
Discharge is by grab-fitted shore cranes at receiving cement plants, power plants, and aluminium smelter terminals.