Yarwun refinery

When the Rio Tinto expansion project was completed at its Yarwun, Queensland alumina refinery, in 2012, it doubled its previous alumina production to 3.4 million tonnes a year. This made Rio Tinto Alcan one of the world's foremost alumina and bauxite producers.

The Yarwun Refinery is a World Class Facility
The Yarwun alumina refinery is a world class alumina refinery located in Central Queensland, ten kilometres north west of Gladstone. The refinery began production of alumina in 2004, two years after construction commencing in 2002. It was the first new alumina refinery to be built in the western world for 20 years.

Bauxite Refined at the Yarwun Refinery is Mined at Weipa
The alumina produced at the Yarwun refinery is mined at Weipa on Cape York Peninsula. Both operations are fully owned by Rio Tinto Alcan. Once refined the alumina is sent to the company's domestic customers as well as being exported to customers in the Middle East and other overseas countries.

The Bayer Process of Refining Aluminum is Used at the Yarwun Refinery
The refining of alumina from bauxite is part of the process in the production of the end product, aluminium. To achieve this the bauxite is processed chemically by what is known as the 'Bayer Process.' This four stage process was developed by Karl Bayer, a German scientist, in 1888:

Stage One - this is known as the 'digestion stage. The bauxite is finely ground before being mixed with a solution of heated caustic soda that dissolves out the alumina that is present in the bauxite.

Stage Two ñ The resulting solution from stage one that is comprised of caustic soda and alumina is then passed through rows of thickener tanks that causes the solid impurities to sink to the bottom as a form of red mud. This red mud is bauxite residue, a by product of the Bayer Process. The residue is then washed many times with water, then neutralised, before being stored is a special residue management area. The remaining clear solution is then sent to the next stage, precipitation, to have the alumina recovered.

Stage Three ñ To begin precipitation, alumina trihydrate is added to the solution through a series of precipitation tanks. This seeds the formation of additional alumina trihydrate crystals.

Stage Four ñ The final stage of the Bayer Process involves the washing of the alumina trihydrate crystals before it is filtered and heated in gas fired kilns at temperatures exceeding 1,100 degrees Celsius. This removes the water molecules and creates a fine white powder which is alumina.

A major benefit from the expansion project in 2012 was the installation of a 160 megawatt cogeneration facility that allowed the Yarwun refinery to reduce greenhouse gas emissions, while at the same time harnessing the heat to create steam that was previously wasted. It was also designed to feed the surplus low emission power back into the Queensland state electricity grid.

The Yarwun alumina refinery is a complex system that incorporates a total of 230 kilometres of piping with thousands of interfaces and chemical processes. The expansion, that began in 2007, provides an additional 250 jobs for local residents of Gladstone.
†