The IMO Sub-Committee on Carriage of Cargoes and Containers issued a circular in October 2015 on the potential liquefaction of bauxite, which is currently categorised as a cargo not at risk of liquefaction. It stated that the risks of carrying bauxite are being investigated, which may lead to an amendment of its classification. In the meantime, caution both from the carrier and shipper’s perspective is required.
Following incidents in Brazil, Indonesia and Malaysia, in particular the BULK JUPITER tragedy in January 2015, in which 18 lives were lost – which some believe to be caused by bauxite liquefaction – the Sub-Committee has issued a circular on bauxite liquefaction that should be read attentively by all parties involved with bauxite.
Liquefaction occurs when a solid acts as a liquid – which can cause a cargo shift on board. It is most likely to occur in loose solids with a high moisture content. The finer the particles, the higher the risk. As pressure is applied – for example from the movement of a vessel due to swell – the water present in the cargo is forced into a lower pressure area. Where the cargo is made up of large particles, water will normally be able to escape to the gaps between the particles. This will not always be possible with fine particles with little or no space between them, however, and the pressure will build until it is released by the solid “flowing”. This potentially causes a cargo shift and can result in instability, listing or even the capsizing of a vessel.
The risk of liquefaction is normally reduced by the requirement that relevant cargoes be notified as belonging to within Group A (cargoes at risk of liquefaction) of the International Maritime Solid Bulk Cargoes (IMSBC) Code. Group A cargoes are subject to a rigorous testing and certifying regime to ensure they are safe to ship. Bauxite, however, is a Group C cargo (cargoes not at risk of liquefaction).
Bauxite under the Code
As listed in Group C of the Code, bauxite has the following properties:
- Moisture content of 0%–10%.
- 70%-90% lumps between 2.5 and 500mm.
- 10%-30% powder.
Heavy rain during open mining will inevitably lead to a higher moisture content, but as bauxite is in Group C it does not need to be tested for its moisture content or flow characteristics.
Recent Code updates
Amendments to the IMSBC Code made in 2013, resolution MSC.354(92) came into force on 1 January 2015. These amendments include among other things numerous new cargoes being classed in Group A. A further resolution (MSC.393(95)), which comes into force on 1 January 2017, will add iron ore fines as a Group A cargo.
There is arguably increasing evidence of bauxite liquefaction, but bauxite remains a Group C cargo under the Code. However, the Sub-Committee has now issued a circular which warns that bauxite may be prone to liquefaction and that its classification may be changed to that of Group A.
The Sub-Committee’s circular therefore advises that a master should not accept bauxite if:
- The moisture content is above 10% and/or particles of size 2.5mm to 500mm do not make up at least 70% of the cargo.
- The cargo is declared as Group A and the shipper has declared the transportable moisture limit1and the actual moisture content is higher than this.
If the competent authority of the loading port determines that the cargo does not present a Group A risk, the master can load.
While the flag state for BULK JUPITER has investigated the loss and concluded liquefaction was the likely cause of the tragedy, the IMO has been more cautious while further investigations are being undertaken. Until a definitive answer is reached concerning the risk of bauxite liquefaction, it would seem appropriate for shipowners and cargo interests alike to treat the carriage of bauxite with caution and to be acutely aware of the dangers inherent in a high moisture content in order to prevent what are avoidable risks.