Portland aluminium smelter

The Portland aluminium smelter, located south of the regional centre of Portland in western Victoria, is owned by a joint venture partnership comprising Alcoa with a 55 percent share and CITEC and Marubeni with 22.5 percent each. The smelter that began smelting alumina in 1986, now produces around 358,000 tonnes of aluminium a year. It is Victoria's largest exporter with its product exported exclusively to the Asian market.

The Portland Aluminium Smelter is Known as the Smelter in the Park

The Portland aluminium smelter is known as being the 'smelter in the park' because of it being sited on 500 hectares of land, 400 of which having been transformed into parklands and wetlands. This has set a worldwide benchmark for environmental and industrial harmony and has become a model for other Alcoa operations in other countries. The Portland aluminium smelter provides work for around 600 people directly employed at the refinery and around 150 contractors.

Aluminium is not a naturally occurring metal. It is mined from the ground as bauxite and refined into a white powder known as alumina. Alumina is smelted into aluminium. It takes two tonnes of alumina to create one tonne of aluminium.

Portland Aluminium Smelter Smelts Alumina Powder Into Aluminium

Alcoa mines its own bauxite in Western Australia where it also refines it into alumina before shipping it to the Portland aluminium smelter for further processing. The alumina produced from the refining process contains aluminium and oxygen. These elements have to be separated through smelting to produce aluminium as a product. It takes between seven and 10 days from when the alumina arrives at Portland before an aluminium ingot is produced.

The Production of Aluminium Requires Many Stages

The first stage in the smelting of aluminium is the manufacturing of anodes to be used during the smelting process.

Anodes are large blocks of carbon that behave as electrical conductors to assist the smelting process. †The Portland aluminium smelter makes around 15,000 anodes each month that weigh about one tonne each. The anodes that are made in the smelters Green Mill are manufactured from recycled anode butts that are returned from previous smeltings, petroleum coke and pitch. They are mixed in heated containers and poured into moulds. Once they are formed they are able to be transferred to the carbon bake.

The carbon bake takes place when the anodes are placed into a furnace and baked to a temperature of 1120 degrees Celsius for two weeks. †This process bakes the pitch in the mixture resulting in a solid block of carbon able to withstand extreme temperatures in the smelting pots.

When ready the anodes are moved to a rodding room where they are mated to a copper rod using molten cast iron. †These rodded anodes are then taken to the potrooms where they are placed into the smelting pots. The Portland aluminium smelter has four 750 metre potrooms that house 103 smelting pots each. It is here where the aluminium is produced.

Alumina is fed into the pot, a graphite lined steel furnace, where it dissolves into molten cryolite, or bath, which is also called aluminium fluoride.† A high electric current, at low voltage, is passed through the pot by means of the anode. This causes the alumina solution to separate its aluminium element from the oxygen. The oxygen immediately reacts with†the carbon anode and becomes carbon dioxide and eventually bubbles away. The separated aluminiun collects at the bottom of the pot. Electricity maintains the pot temperature at 960 degrees Celsius.

The aluminium is then siphoned from the pot and taken to the ingot mill where it is casted.