Alumina Carrier: The Dedicated Powder Bulk Ship
The dedicated alumina carrier: aerated hold bottoms, shipboard pneumatic discharge, hold coating for a white cargo, and the trade economics that justify the specialisation.
A dedicated alumina carrier is a bulk carrier arranged to load and discharge fine alumina without shore unloading equipment, using aerated sloping hold bottoms that fluidise the cargo and feed it to a central suction point, with shipboard pneumatic or mechanical systems delivering it ashore. The type exists because smelters want continuous delivery into an enclosed feed system rather than into an open hopper.
The full article will cover the hold arrangement and the aeration system, the discharge machinery including vacuum and pressure re-loader tanks working in tandem for near-continuous flow, and the rates such systems achieve against conventional grab discharge.
It will also cover the reasons the specialisation pays and the reasons it is limited. Dedicated tonnage holds hold coatings in the condition a white cargo demands, which conventional tonnage on spot fixtures generally cannot. Against that, the ships are constrained in what else they can carry, and the trade is a minor bulk, so the fleet is small and the economics depend on long-term contracts of affreightment rather than the spot market.