SAFETY 55
INGLORIOUS MUD BULK • JOHN SOUTHAM, LOSS PREVENSION DIRECTOR AT NORTH P&I CLUB, INTRODUCES THE RISKS OF A BAUXITE BYPRODUCT NOW EMERGING AS A CARGO FOR BULK CARRIERS AS CARGOES SHIPPED by sea in bulk, bauxite and bauxite fines are commonly carried and their characteristics are generally well known and understood by bulk carrier operators. However, a by-product of the bauxite refining process is now emerging as a cargo. This product is generally referred to as ‘red mud’. Red mud can be declared under a number of different names, including alumina refinery residues (ARR), bauxite refinery residue (BRR), Bauxsol, neutralised red mud (NRM),
JOHN SOUTHAM: SHIPOWNERS SHOULD BE HIGHLY CAUTIOUS OF ACCEPTING A SHIPMENT OF RED MUD
neutralised alumina refinery residues (NARR), un-neutralised red mud (UNRM) or CO²neutralised red mud (CNRM). But, regardless of the label, the risks remain the same. Red mud is highly alkaline and difficult to deal with, and is considered a low-quality product. However, notable demand for it is now being reported from the Middle East and China, where a number of processes to extract components such as iron are undergoing laboratory or field trials. It is understood that none of these has progressed to full industrial scale as yet, though the work is more advanced in China, where the cost of iron ore and new environmental constraints mean there is a drive for recovery.
At present, its significant environmental hazard means that red mud is generally stored in large and highly toxic tailing dams, due to its limited uses and concerns over its safe shipment. TAKING A RISK? The carriage of red mud in bulk is a high-risk operation. It is known to be a highly variable cargo and often 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 1 mm 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 higher concentration of super-fine particles known 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. Furthermore, 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 International Maritime Solid Bulk Cargoes (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. www.nepia.com
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