Zinc concentrate is a major dry bulk cargo, with global seaborne trade of approximately 12 to 15 million tonnes per year of dry-tonne equivalent. The cargo is principally moved from major mining regions (Australia, Peru, Bolivia, Mexico, Canada, the United States, and Russia) to smelters in China, South Korea, Japan, Spain, Norway, and elsewhere. The IMSBC Code regulates zinc concentrate shipments under a Group A schedule.
Schedule structure
The IMSBC Code includes the following zinc-related schedule entries:
- Zinc concentrate (Group A): sphalerite-rich beneficiated zinc concentrate from flotation milling. Liquefiable, subject to TML and MC certification.
- Zinc and lead calcines (mixed): thermally treated mixed concentrates. Group A or B depending on composition.
- Zinc dross (UN 1435): a hazardous oxidising waste material from galvanising operations. Separate IMDG and IMSBC handling.
- Zinc ashes (UN 1435): similar by-product material from zinc processing. Group B.
This article focuses on zinc concentrate, the dominant zinc bulk cargo.
Cargo properties
Zinc concentrate is produced from sphalerite (ZnS) deposits, often in association with lead sulphide (galena, PbS) and minor copper sulphides. The flotation milling process produces a fine concentrate with zinc content typically 50 to 60 per cent by mass. Bulk density is approximately 2.4 to 2.8 tonnes per cubic metre, with stowage factor of approximately 0.36 to 0.42 cubic metres per tonne. Moisture content at loading is typically 7 to 10 per cent.
The cargo handling characteristics closely resemble copper concentrate: fine particle size, high density, moderate moisture, and significant liquefaction risk. The Group A IMSBC procedures (TML, MC certification, Proctor-Fagerberg testing) apply.
Major routes
Zinc concentrate seaborne trade flows include:
- Australia to Asia: Mount Isa, Cannington, Century, Dugald River mine production exported through northern Queensland ports.
- Peru to Asia and Europe: Antamina, Cerro de Pasco, and other Peruvian operations exporting through Callao.
- Bolivia to Asia and Europe: San Cristóbal mine production through Chilean and Peruvian Pacific ports.
- Mexico to Asia and Europe: Peñoles and Industrias Peñoles operations through Pacific and Atlantic ports.
- Canada to Europe and Asia: Trail BC and Manitoba operations.
- Russia to Europe: Norilsk Nickel polymetallic concentrates (subject to sanctions complications since 2022).
China is the dominant single importer, supplying the world’s largest zinc smelting industry.
Loading and discharge
Loading is by shore conveyor and shiploader at major export terminals. The cargo self-trims and standard Group A pre-loading testing applies. Discharge is by grab-fitted shore cranes at receiving smelter terminals.
Polymetallic concentrate variants
Many zinc deposits produce polymetallic concentrates containing significant copper and/or lead. Such concentrates are shipped under the “mineral concentrates” generic IMSBC entry with composition declared on the cargo documentation. Polymetallic concentrate handling is identical to single-metal concentrate handling for marine carriage purposes; the smelter selects the appropriate processing route based on the declared composition.