Lead concentrate is a moderate-volume dry bulk cargo, with global seaborne trade of approximately 4 to 6 million tonnes per year of dry-tonne equivalent. The cargo is principally moved from Australian, Peruvian, Mexican, and Russian mining regions to smelters in China, South Korea, Japan, India, and elsewhere. The IMSBC Code regulates lead concentrate shipments under a Group A schedule with additional handling provisions reflecting lead toxicity.
Schedule structure
The IMSBC Code includes the following lead-related schedule entries:
- Lead concentrate (Group A and B): galena-rich beneficiated lead concentrate from flotation milling. Liquefiable (Group A) and presents toxicity hazards (Group B). Subject to TML and MC certification plus toxicity-related handling.
- Lead and zinc calcines (mixed): thermally treated concentrates. Group A or B depending on composition.
- Lead nitrate (UN 1469): a strong oxidiser, separate hazard category.
- Lead silicate (UN 1828): a different lead compound, separate handling.
This article focuses on lead concentrate, the dominant lead bulk cargo.
Cargo properties
Lead concentrate is produced principally from galena (PbS) deposits, often with co-occurring sphalerite (zinc sulphide) and minor copper and silver sulphides. The flotation milling process produces a fine concentrate with lead content typically 60 to 75 per cent by mass. Bulk density is approximately 3.0 to 3.8 tonnes per cubic metre — exceptionally high, reflecting the high specific gravity of galena (7.6). Stowage factor is approximately 0.27 to 0.33 cubic metres per tonne.
Moisture content at loading is typically 7 to 10 per cent. The high cargo density makes lead concentrate one of the most heeling-prone cargoes if liquefaction occurs, and bulk carrier hold structural loading is a significant consideration.
Lead toxicity hazards
Lead concentrate presents two principal toxicity hazards:
- Inhalation of lead dust: airborne lead dust generated during loading, voyage motion, and discharge is acutely toxic via inhalation. Crew exposure must be controlled through enclosed loading and discharge systems, dust suppression, and personal protective equipment.
- Lead contamination of marine environment: any spillage or leakage during loading or discharge can contaminate port waters and sediments. Modern terminals operate under strict environmental controls.
The IMSBC Code requires:
- Personal protective equipment for crew handling lead concentrate.
- Restricted access to cargo holds and adjacent enclosed spaces.
- Dust suppression and enclosed handling at loading and discharge.
- Hold cleaning and decontamination after discharge with appropriate disposal of contaminated wash water.
Liquefaction risk
Lead concentrate is liquefaction-prone for the same reasons as copper and zinc concentrate: fine particle size, high density, moderate moisture content. The Proctor-Fagerberg test determines TML on lead concentrate cargoes. Pre-loading certification and the 90 per cent of TML loading limit apply.
Major routes
Lead concentrate seaborne trade flows include:
- Australia to Asia: Mount Isa, Cannington, McArthur River mine production through northern Queensland ports.
- Peru to Asia and Europe: Cerro de Pasco and Antamina exports through Callao.
- Mexico to Asia and Europe: Peñoles operations.
- Russia to Asia: Far Eastern operations (subject to sanctions complications since 2022).
Loading and discharge
Loading is by enclosed shore conveyor and shiploader with strict dust suppression. Discharge is by grab-fitted shore cranes with covered hopper discharge at receiving smelter terminals. Hold cleaning after discharge is performed under controlled conditions to manage lead-contaminated residues.