During latest IMO’s Sub-Committee on Carriage of Cargoes and Containers (CC4), IMO raised awareness on the hazards of bauxite cargo and updated a previous circular, noting that some bauxite cargoes (specifically those with a larger proportion of smaller particles) present a risk caused by moisture and should be treated as Group A cargoes.
Excess moisture in such cargoes can lead to a free surface slurry, IMO highlights. This can cause atypical motion of the ship (wobbling). The master should take appropriate action in the event of this possible sign of cargo instability.
The circular includes the draft Test Procedure for Determining the transportable moisture limit (TML) for bauxite; the draft individual schedule for bauxite of Group A (Bulk Cargo Shipping Name “BAUXITE FINES”); and draft amendments to the existing individual schedule for bauxite of Group C (bauxite with a lower proportion of smaller particles and with a degree of saturation by moisture not liable to reach 70%).
In particular, the circular refers that bauxite fines cargoes may be subject to quasi-liquefaction, technically known as “Dynamic Separation”, leading to potential capsize-hazards on ships transporting this cargo. Therefore, empirical research suggests that BAUXITE FINES, as determined by Particle Size Distribution factors and other characteristics together with a new IMSBC Test Procedure, can exhibit Group A characteristics . When a slurry is formed, other forces acting on the ship can lead to a free-surface effect and potential capsize issues.
Cargoes subject to potential liquefaction issues are referred to as Group A cargoes in the current International Maritime Solid Bulk Cargoes (IMSBC) Code. The IMSBC Code contains an individual schedule for BAUXITE, which is a Group C cargo defined as liable to neither liquefy (Group A), nor to possess chemical hazards (Group B).
In a safety advisory, the Marshall Islands would like to draw operators’ attention to the following important issues:
- A new draft individual IMSBC schedule for BAUXITE FINES contained in the IMO Circular CCC.1/Circ.2-Rev.1 referencing Bauxite-cargoes as either Group C (BAUXITE) or Group A (BAUXITE FINES); and
- Information suggesting that ships undergoing a quasi-liquefaction BAUXITE FINES cargo-related issue may experience an atypical motion (wobbling) as a precursor to capsize. Masters and others are invited to take note of this motion and act expeditiously should it be experienced.
Further details may be found by reading IMO’s circular herebelow:
