Key data
| Stowage factor | 0.30–0.45 m³/t (typical 0.38)10.6–15.9 ft³/t (typical 13.4) |
|---|---|
| Form | Bulk |
| IMSBC group | A Cargoes that may liquefy if shipped above their moisture limit. |
| BCSN | IRON ORE FINES |
ft³/t values are per metric tonne (1 m³/t ≈ 35.31 ft³/t). Stowage factors are indicative — see note below.
Description
Iron ore fines are the fine-grained product of ore processing and one of the largest dry bulk trades by volume. Because the cargo is extremely dense, a bulk carrier loads down to her marks while the holds are still far from full, making this a classic deadweight cargo where intake is set by available deadweight rather than cubic capacity. The defining commercial and safety feature, however, is how it behaves when wet.
Stowage & loading
Loading is rapid, by conveyor or grab from stockpiles, and the dense cargo concentrates low in the hold, which keeps the centre of gravity low but produces high local loads on the tank top. The pour is trimmed reasonably level. The critical control is not the geometry of the stow but the moisture condition of the cargo presented for loading, which must be established before any tonnes are taken on board.
Hazards & handling
The dominant hazard is liquefaction. When fine ore carries more moisture than it can safely hold under the vibration and motion of a voyage, the packed cargo can lose its structure and behave as a near-liquid slurry, shifting to one side and creating a free surface that destroys stability. Many bulk carriers and their crews have been lost this way. The danger is hidden, because a parcel can look dry at the surface while being saturated within.
Carriage & discharge
A cargo accepted within safe moisture limits is monitored through the voyage for any sign of shifting or free water, with the master alert to changes in the ship's behaviour. Discharge is by grab or, increasingly, continuous unloaders, and residues are washed down on completion. Where there is any doubt about moisture at the load port, the safe course is to stop and resolve it before sailing rather than to sail and manage it at sea.
Key hazards
- Liquefaction when moisture exceeds the transportable moisture limit, causing a sudden cargo shift and loss of stability
- A free surface of liquefied cargo that can capsize the ship with little warning
- High point loading on the tank top from a dense, concentrated stow
Loading precautions
- Obtain a valid certificate of moisture content and transportable moisture limit before loading, and stop if moisture approaches the limit
- Treat a dry-looking surface with suspicion; saturation can sit below an apparently dry top layer
- Confirm the cargo's flow characteristics where rain, stockpile drainage or handling may have raised moisture
Stowage factors are indicative and vary with grade, origin, moisture and packing. Always verify against the shipper's cargo declaration and the applicable IMSBC Code schedule before fixing or loading. This is general information, not professional or safety advice.