Bauxite

Content maintained by Paul Kay

• Bauxite
• Resources
• Accessible EDR
• JORC Reserves
• Exploration
• Production
• World Ranking
• Industry Developments

Bauxite is a heterogeneous naturally occurring material from which alumina (Al₂O₃) and aluminium metal are produced. The principal minerals in bauxite are gibbsite (Al₂O₃.3H₂O), boehmite (Al₂O₃.H₂O) and diaspore, which has the same composition as boehmite, but is denser and harder.

Australia is the world's largest producer of bauxite, with 31% of global production in 2008. The bauxite resources at Weipa in Queensland (Qld) and Gove in the Northern Territory (NT) have almost 50% available alumina and are amongst the world's highest grade deposits. Other deposits located in Western Australia's (WA) Darling Range, Mitchell Plateau and Cape Bougainville, the latter two of which have not been developed, are relatively low grade at around 30% available alumina.

More than 85% of the bauxite mined globally is converted to alumina for the production of aluminium metal. An additional 10% goes to non-metal uses in various forms of specialty alumina while the remainder is used for non-metallurgical bauxite applications. In most commercial operations, alumina is extracted (refined) from bauxite by a wet chemical caustic leach process known as the Bayer process. Alumina is smelted using the Hall-Heroult process to produce aluminium metal by electrolytic reduction in a molten bath of natural or synthetic cryolite (NaAlF₆).

Australia's aluminium industry is a highly integrated sector of mining, refining, smelting and semi-fabrication centres and is of major economic importance nationally and globally. The industry consists of five bauxite mines, seven alumina refineries, six primary aluminium smelters, 12 extrusion mills and two rolled product (sheet, plate and foil) mills. The industry in Australia is geared to serve world demand for alumina and aluminium with more than 80% of production exported. Figures on the value of industry exports are collated half-yearly by the Australian Bureau of Statistics (ABS) and the Australian Bureau of Agricultural and Resource Economics (ABARE) publishes quarterly production and export data on bauxite, alumina and aluminium.

The long-term future of Australia's aluminium industry is underpinned by vast resources of bauxite located in the Weipa and Gove regions adjacent to the Gulf of Carpentaria in the NT, and the Darling Range south of Perth, WA. Deposits in these regions rank among the world's largest identified resources in terms of extractable alumina content. The undeveloped bauxite deposits at Mitchell Plateau and Cape Bougainville in northern WA are not currently economic to develop, but are a significant potential future resource.

Economic Demonstrated Resources (EDR) of 6.2 gigatonnes (Gt) in 2008 remained consistent with the previous year. The nett change in overall demonstrated resources was minor with additions resulting from exploration drilling being offset by depletions created through mine production.

About 95% of bauxite EDR is accessible for mining. Some areas within mining leases in the Darling Range in WA in particular are not available for extraction for environmental reasons. The ratio of Accessible Economic Demonstrated Resources to current mine production shows the resource life of existing bauxite operations is around 70 years. Significant potential exists for further mineral exploration and reserve delineation to extend the current resource life estimate.

Approximately 30% of AEDR comprises JORC Code ore reserves as reported by industry. The remaining represents resources assessed by Geoscience Australia as being economically recoverable from measured and indicated categories of mineral resources, as defined under the JORC Code and other classification systems used by companies not listed on the Australian Stock Exchange. The surface expression of bauxite and confidence in lateral continuity of thickness and grade make it possible in certain terrains to classify some inferred resources as EDR.

Data on exploration for bauxite specifically are not available nationally.

Australia was the leading producer of bauxite and alumina globally in 2008, and the fifth largest aluminium producer. Based on International Aluminium Institute data, production totalled 63 million tonnes (Mt) of bauxite (31% of world production), 19.7 Mt of alumina (33%) and 2 Mt of aluminium (8%). However, significant declines in the prices obtained for bauxite, alumina and aluminium since mid-2008 are not yet fully reflected in the Institute data. Expansion of the Weipa (Qld) bauxite production operations south of the Embley River is under consideration, including the potential for construction of a new deepwater port. Other bauxite extraction projects are under consideration on Cape York Peninsula (Qld) and the Darling Range area (WA).

Based on United States Geological Survey (USGS) data for other countries, Australia's demonstrated bauxite resources of 7.9 Gt rank second in the world after the Republic of Guinea and ahead of Vietnam, Brazil, Jamaica and China.

Aluminium is a product of increasing importance for manufacturing because of its light weight, strength and durability as well as its capacity to be recycled. On a life cycle assessment basis, the high strength to weight ratio of aluminium results in significant fuel savings, particularly where substitution can be made for heavier construction materials.

The expansion of Australian bauxite, alumina and aluminium production in the past few years reflects high demand for the commodities and all three maintained high levels of production during 2008, with significant investments being undertaken in prospective projects. Along with the well developed production areas around Weipa (Qld), Gove (NT) and the Darling Range (WA), bauxite occurrences on the Mitchell Plateau and Cape Bougainville (WA), Cape York (Qld) and central New South Wales (NSW) maintained sector interest.