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Web alert: Bauxite liquefaction

12 January 2015

There are many detailed guides on the subject including The Standard Club’s cargo publication on liquefaction that is free to download on the right.

Whilst most mineral concentrates are covered under the International Maritime Solid Bulk Cargoes (IMSBC) code as group A (cargoes which may liquefy if shipped at a moisture content in excess of their transportable moisture limit), Bauxite is listed as a separate entry and as a group C cargo.  The club has experienced a number of cargoes (including Bauxite) that, though listed as a Group C cargo, are exhibiting the liquefaction characteristics of group A cargoes.  Typically, these cargoes have a high proportion of fine-particles. 
 
A growing number of shippers routinely categorise Bauxite as group C, neither prone to liquefaction (group A) nor possessing a chemical hazard (group B), without acknowledging that, in order to be classified as group C, Bauxite must have properties within the following parameters: 

  • Moisture content 0% to 10%
  • 70% to 90% lumps;  varying between 2.5 mm and 500 mm 
  • 10% to 30% powder 

If the Bauxite cargo proposed for loading does not meet the properties listed in the IMSBC Code, or if a ‘can test’ or ‘splatter test’  raises any doubts about the fluidity of the cargo, the requirements of section 1.3 of the IMSBC Code, “Cargoes not listed in this Code“, should be followed.
 
Members should be aware that Bauxite is not always group C and there are many conditions that may take the cargo outside this specification, such as high moisture content due to heavy rainfall, high proportion of fines, or some mines (particularly in Malaysia and Indonesia) using water cannons to wash Bauxite fines and lumps through sieves. This action is designed to reduce lumps to below 100mm but significantly increases the moisture content of the cargo, sometimes by as much as 15% by the time the Bauxite reaches the storage area. This changes the properties of the cargo from one with a low moisture content that is not ordinarily prone to liquefaction, to a cargo which may liquefy during a voyage (i.e. from group C to group A)

Appendix 3 paragraph 2.1 of the IMSBC Code, states:
“Many fine-particled cargoes, if possessing sufficiently high moisture content, are liable to flow. Thus any damp or wet cargo containing a proportion of fine particles should be tested for flow characteristics prior to loading”.
 
Section 4 4.2.1 of the IMSBC Code specifically states:
 “The shipper shall provide the master or his representative with appropriate information on the cargo sufficiently in advance of loading to enable the precautions which may be necessary for proper stowage and safe carriage of the cargo to be put into effect”
 
The club recommends ships loading Bauxite to:

  • clarify the method used to determine the moisture content; 
  • carefully check the shipper’s cargo declaration and stated moisture content as described in the certificate provided;
  • check cargo to be loaded in each barge or stockpile for excessive water content;
  • if high rainfall occurred in the days prior to loading, request new moisture content tests to be carried out. This is especially important during monsoon seasons;
  • ensure that a valid moisture content certificate is issued before loading, in accordance with IMSBC sections 4.3 & 4.5,  and that its validity can be confirmed;
  • consider clausing their charter party to include that all statutory provisions of the IMSBC are to be followed and stipulate that it is owner's right to have an independent surveyor in attendance.

If there any concerns or doubts of the validity of the moisture content, the ship’s master should ensure that:

  • further advice and assistance is obtained from independent reputable cargo expert and the owner and P&I club are informed;
  • cargo is not loaded until the correct information about the cargo has been received.