Handling bauxite & alumina - Port Technology International

ENGINEERING & EQUIPMENTAfter the alumina is ‘vacuumed’ from the ship hold, it isseparated from the conveying air thanks to a special large-sizeair filter before passing through a special designed valve (seepicture on pxx), down to a chain conveyor which transports thealumina to the top of the quay hopper, for instance. The end ofthis conveyor has one or two loading telescopic chute(s) with acover to provide a seal around thealumina’s entrance into the hopper(see picture above).When entering into thereceiving hopper, the alumina flowsdown gently in such a way that itwill be easily conveyed downwards.This means handling must becontrolled very carefully from thenegative to normal pressure area,in order to be continuouslyconveyed at a determined rate.VIGAN technology achievesthis control thanks to itsengineering and equipment designto precisely monitor the amountof alumina in the receiving tankand its flow down to the conveyorthrough a specially designed valve.This technology allows for theelimination of all the maintenancecosts of an airlock for instance,which often suffers significant weardue to the abrasive nature ofalumina.Special sealing features ensure that no dust will escape out ofthe mechanical conveyor and the dust at transfer points iscontinuously collected thanks to a suction fan with self-cleaningfilter.Moreover, as they are self-propelled on rails or tyres, theunloaders are able to move easily along the ship and noadditional equipment (such ashoppers) must be displaced toensure quick and reliable unloadingoperations and eventual packing(see picture, left). VIGAN is alsoable to design and manufacture theentire bagging system.In all equipment, a frequencyconverter — also called a speedvariator, or an inverter — allows forthe continuous and precise controlof the suction pattern, as well assignificant energy consumptionsavings.With equipment for aluminaunloading already commissioned inseveral countries such as Finland,France, Poland, China and Iran,VIGAN has gained a large amountof experience regarding this rawmaterial handling in bulk. This costeffectivetechnology for aluminaunloading is a most promisingalternative for many ports and thealumina processing industry.JULY 2012DCi31