Challenges of Mineral Bulk Shipping
With the recent lifting of the moratorium on Iron ore exports from India and the loss of two bulk cargo ships last year, the timing for a presentation on the Challenges of Mineral Bulk Shipping seemed rather appropriate. For those of you unlucky few who missed the event on Wednesday 21st May, here is a quick overview of what our guest speaker, Andy Wells, talked us through.
For a room full of mining people, a talk on shipping could have almost been a foreign language. There were a few, including myself, who were close to falling at the first hurdle trying for example to work out who was responsible for what between the producer, shipper, vessel owner, charterer, receiver and insurer. Millions of tonnes of bulk mineral commodities are shipped around the world every year and normally these voyages progress without incident, thanks to constant improvements to the IMSBC Code. However, it is a lot more common than you might expect that valuable cargoes are damaged, written off or even lost at sea.
Essentially the easiest way to explain the challenges is by dividing the cargo up into the following three categories of bulk cargo classification:
- Group A is the risk of liquefaction if the product is shipped above its Transportable Moisture Limit (TML).
- Group B is a chemical hazard.
- Group C covers all other bulk cargos.
A typical Class A bulk cargo could be nickel laterites, fine coal, iron ore fines or even mineral concentrates (although not as prevelant in tonnage terms). The problems with liquefaction can occur prior to loading where the poor management of stockpiles allows cargo moisture content to build up. We were showed pictures of ‘poor husbandry’ where product was left uncovered next to pools of water, even with vegetation growing on it! Despite it still appearing dry, it may be above the TML. Ships’ Masters are routinely pressured into shipping potentially unsafe cargos for ”commercial” reasons. With the right conditions at sea (most often stormy) and a cargo above its TML it has spelt disaster on numerous occasions. This is a particular problem in certain locations such as, but not exclusive to; India, Indonesia, New Caledonia and the Philippines. With pictures telling a thousand words, the following diagram best describes what happens. Essentially the initial state of the cargo is ‘moist’ with pockets of air mixed in. Shear forces compress the particles, releasing the air out of the mixture and turning substance into a viscous liquid. The resonating slosh of the liquid from side to side inside the vessel, is enough to sink it.
We were told that there are no photographs of a fully liquefied cargo, for obvious reasons. However, the following images are courtesy of CWA of partially liquefied Iron Ore cargoes.
The latter part of the talk concentrated on Group B, Chemical Hazards. This is a smorgasbord of potential problems including corrosion, self-sustained decompisition, hydrogen explosions, self heating, poisonous gas release to name a few.
The following are examples of cargoes that can self heat.
- Sulphide concentrates (containing; Copper, lead, Zinc, Pyrite, Pyrrhotite)
- Iron products (DRI, HBI)
- Coal (containing pyrite)
The following photo courtesy of Agencia EFE is a self-sustaining decompositon that occurred out at sea. It was eventually brought under control by smothering the cargo with seawater, however writing off the cargo.
In summary, mineral bulk shipping is relatively safe provided the rules are followed. These rules are constantly changing in the light of experience gained from shipping accidents and disputes around the world. We all have a commercial interest in the safe and commercially viable carriage of bulk cargoes. Sometimes we forget just how important the route to market really is and its potential impact on a project’s cash flow and reputation.
The AMA would like the thank Andy and CWA for taking the time to speak and also for sponsoring the bar tab!