Our world class Yarwun alumina refinery is situated ten kilometres north-west of Gladstone in central Queensland. Construction began in 2002 and the first shipment of alumina was made in late 2004. The refinery was the first greenfield refinery to be built in the western world in 20 years.
An aluminium ore known as bauxite is transported from Rio Tinto Aluminium’s mining operations in Weipa on Western Cape York to be processed into alumina at the Yarwun refinery, which is 100 per cent owned and operated by Rio Tinto Aluminium.
Recent expansions have more than doubled production at the Yarwun refinery to 3.4 million tonnes of alumina per year, making Rio Tinto Aluminium one of the world's leading alumina producers.
Yarwun’s alumina is shipped to customers in Australia and overseas, including the Middle East.
Refining alumina (aluminium oxide) is the second step in the production of aluminium.
Alumina is refined from bauxite using a chemical process known as the Bayer Process. Invented in 1888 by German scientist Karl Bayer, this process has four stages.
Bauxite is finely ground in mills and then mixed with a hot, caustic soda solution which dissolves the alumina contained in the bauxite.
The solution of alumina and caustic soda passes into rows of thickener tanks, where the solid impurities sink to the bottom as a fine red mud. The red mud (or bauxite residue) is a by-product of the process. It is washed several times with water, neutralised, and then stored at the residue management area. The clear solution is sent to the precipitation stage for the alumina to be recovered.
Alumina trihydrate is added to the alumina solution in a line of precipitation tanks to seed the formation of additional alumina trihydrate crystals.
The alumina trihydrate crystals are washed, filtered and then heated in gas-fired kilns at temperatures greater than 1,100°C to remove water molecules, creating a fine white powder known as alumina.
Rio Tinto Aluminium Yarwun uses leading-edge technology and environmental design features, which are incorporated into the expanded refinery. A key element of the expansion is a 160 megawatt cogeneration facility, which allows us to reduce our greenhouse gas intensity, harness heat to create steam that would otherwise be wasted, and feed surplus, low emission electricity back into the Queensland electricity grid.