Mud, Mud, Glorious mud… or is it?

With around 40% of North P&I Club’s 200 million gross tonnage in the bulk carrier sector, the organisation has a long history of safety expertise for ships and crew. John Southam, Loss Prevention Executive speaks about the risks of a bi-product now emerging as a cargo for shipment.

 

The bulk cargoes bauxite and bauxite fines are both commonly-carried cargoes and their characteristics are generally well-known - and understood - by bulk carrier operators. However, a bi-product from the bauxite refining process is now emerging as a cargo for shipment. This product is commonly referred to as red mud.

 

Red mud can be declared under numerous different names, including ARR (alumina refinery residues), BRR (bauxite refinery residue), Bauxsol, NRM (neutralised red mud), NARR (neutralised alumina refinery residues), UNRM (un-neutralised red mud), CNRM (CO₂ neutralised red mud).

 

Regardless of the label, the risks remain the same.

 

 

As a highly alkaline and difficult to deal with material, red mud is considered to be a low-quality product. However, notable demand is reported from regions such as the Middle East and China. There are a number of laboratory and field trials of processes to extract components such as iron from red mud although it is understood that none of these have progressed to full industrial scale as yet. This work is more advanced in China, where the cost of iron ore and new environmental constraints mean there is a drive for recovery.

 

As a significant environmental hazard red mud is generally stored in large and highly toxic tailings dams due to its limited uses and concerns over safe shipment.

 

 

The carriage of red mud cargo is a high-risk operation. It is known to be a highly variable cargo, and often very fine. Furthermore, as well as being a potentially usable product it can also be carried as a waste product.

 

Red mud commonly contains a large proportion of fine particles less than 1mm in size and generally has a very high relative moisture content. Once on board, even an apparently stable cargo has been known to break down very quickly once the cargo is repeatedly stressed by exposure to wave energy. This is of particular concern for smaller bulk carriers on longer voyages.

 

Some versions of the cargo can resemble slurry, which results from a high concentration of super fine particles know as ‘slimes’.

  

Experts have reported vessels being unable to leave the anchorage directly after loading red mud because of this cargo’s adverse effect on the vessel’s stability. Once on board, should a problem occur then de-watering operations may be the only action possible to stabilise the cargo, which can prove costly and result in significant delays.

 

The cargo is also highly caustic (high pH) making it corrosive to the vessel’s steel hull as well as being hazardous to human health through contact with the skin.

 

 

Shipowners should therefore be highly cautious of accepting a shipment of red mud – it should be considered a high-risk operation. Red mud does not have a schedule in the IMSBC code and North P&I is not aware of any plans for it to be included in the future, most likely due to the high variability of the cargo. Therefore, red mud falls under section 1.3 of the IMSBC Code and should be carried accordingly; ship operators should seek expert advice prior to accepting a cargo of red mud.