The International Maritime Organization has issued a new warning that a newly-discovered phenomenon – different from cargo liquefaction – could cause bauxite cargoes to become unstable when carried in bulk on a ship, potentially causing the vessel to capsize and sink.
Bauxite, a type of rock, is one of the world’s major sources of aluminium with around 100 million tonnes transported annually by sea. Although extremely rare, bauxite cargoes have been known to liquify and shift during shipping, which can cause a vessel to capsize at a moments notice.
In 2015, the Bahamas-flagged MV Bulk Jupiter unexpectedly sank off the coast of Vietnam while transporting 46,000 metric tons of bauxite loaded in Malaysia. All but one of the ship’s 19 crew members were lost in the accident.
While bauxite has been classified under the International Maritime Solid Bulk Cargoes (IMSBC) Code as a low-risk Group C cargo, under certain circumstances, in rare cases it has been known to exhibit liquefaction characteristics similar to high-risk ‘Group A’ cargoes. The IMSBC Code is the industry rulebook on how to deal with bulk cargoes.
In response to the Bulk Jupiter accident, the IMO requested that the global bauxite industry undertake research into the behavior and characteristics of bauxite cargoes during ocean transportation, leading to the formation of the Global Bauxite Working Group (GBWG). The group presented its findings from its research to an IMO Sub-Committee this week.
According to their report, the group found that certain forms of bauxite with a large proportion of smaller particles could be subject to a newly-identified phenomenon of “dynamic separation” when there is excess moisture in the cargo.
In such conditions, a liquid slurry (water and fine solids) can form above the solid material, according to the report. The resulting free surface effect of liquid “sloshing about” could significantly affect the vessel’s stability, leading to the risk of the ship capsizing.
To raise awareness about the potential risks posed by moisture, IMO’s Sub-Committee on Carriage of Cargoes and Containers, which met this month at IMO Headquarters, issued new guidance on the carriage of bauxite in the form of a circular aimed at shippers, terminal operators, shipowners, ship operators, charterers, shipmasters and all other entities concerned.
The circular requests that extreme care and appropriate action be taken, taking into account the provisions of relevant IMO instruments, when handling and carrying bauxite in bulk.
The circular takes immediate effect, ahead of the next scheduled adoption (in 2019) of the new test methods and relevant schedules for bauxite cargoes during the routine scheduled updating of the International Maritime Solid Bulk Cargoes (IMSBC) Code.
The new circular updates a previous circular on the carriage of bauxite issued in 2015 following the Bulk Jupiter sinking, and invites Governments to note 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. 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 IMO circular says.
The circular also 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%).