The Worsley Alumina Refinery is named after the historic timber settlement of Worsley, near Collie in the south west corner of Western Australia. The history of the project goes back to the early 1960s when a group of local entrepreneurs formed a firm to explore, develop and sell deposits of bauxite ore on the eastern side of the Darling Range, near Boddington.
Construction of a mine site and refinery began in 1980 and the first alumina was produced in April 1984. These days Worsley Alumina is a joint-venture partnership between BHP Billiton (86%), Japan Alumina Associates (Australia) (10%) and Sojitz Alumina (4%).
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In May 2000, Worsley completed a $1bn expansion increasing annual production to 3.1 million tons.
The Worsley Alumina Development Capital Project (DCP), which commenced in 2004, was completed in 2007 at a cost of US$ 235m (US$ 188m our share), resulting in a 0.25 mtpa increase in alumina production (0.215 mtpa our share) to 3.5 mtpa.
In 2008 the partners announced a US$ 2.21bn ‘Efficiency & Growth’ expansion project at Worsley Alumina. This includes approximately US$ 70m of sustaining capital.
BHP says that the expansion project will lift capacity of the Worsley refinery from 3.5 million tons per annum (Mtpa) of alumina to 4.6 Mtpa (100% capacity) through expanded mining operations, additional refinery capacity and upgraded port facilities. Production is expected to commence in the first half of calendar year 2011. Worsley is currently the world’s fifth biggest bauxite mine.
BHP Billiton Aluminium President Jon Dudas said, “Worsley is one of the largest, lowest cost and most efficient alumina refineries in the world. This decision to invest in further production capacity underlines our confidence in the future of the alumina market. It also reflects our confidence in Worsley Alumina’s ability to continue its excellent track record of production growth.”
Alumina is carted by rail and exported through the Port of Bunbury. More than 1200 people are employed at the mine site and refinery. Many more jobs have been created through the employment of sub-contractors and through the support of local businesses and suppliers.
Geology and reserves
The Bunbury basalt has been dated at 135 and 128 Ma and overlies an erosional surface, thus marking the breakup of unconformity and volcanism in South Western Australia. It has been traced in the subsurface southwards and also offshore to the North East. Seismic evidence under the continental shelf between Perth and Bunbury shows that the Basalt flowed down an odd valley incising the continental margin. The Worsley mine has estimated reserves of 400mt.
Mining
Bauxite is mined from reserves mainly within State forest on the eastern edge of the Darling Range, near Boddington. The bauxite is crushed and carried 51km by a two-flight cable belt conveyor system to the refinery site at Worsley. It is then processed, and the separated alumina is carted by rail and exported through the Port of Bunbury.
Ore processing
The Worsley alumina refinery uses the Bayer process to produce metallurgical grade alumina, which is used as feedstock for aluminium smelting. Power and steam needed for the refinery are provided by a joint venture-owned onsite coal power station and a non-joint venture-owned on-site gas fired steam power generation plant.
Production
The partners have stated that the US$ 2.21bn ‘Efficiency & Growth’ project at Worsley Alumina will lift capacity of the Worsley refinery from 3.5 million tons per annum (Mtpa) of alumina to 4.6 Mtpa (100% capacity) through expanded mining operations, additional refinery capacity and upgraded port facilities.
