Bauxite

Content maintained by Paul Kay

• Bauxite
• Resources
• Accessible Economic Demonstrated Resources
• Joint Ore Reserve Committee Reserves
• Exploration
• Production
• World Resources
• 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 33 per cent of global production in 2007. The bauxite resources at Weipa (QLD) and Gove (NT) have nearly 50 per cent available alumina and are amongst the world's highest grade deposits. In Western Australia, deposits in the Darling Range and the undeveloped Mitchell Plateau are relatively low grade with around 30 per cent available alumina.

More than 85 per cent of the bauxite mined globally is converted to alumina for the production of aluminium metal. An additional 10 per cent goes to non-metal uses in various forms of specialty alumina and the remainder is 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 is geared to serve world demand for alumina and aluminium with more than 80 per cent of production exported. Figures on the value of industry exports are collated half-yearly by the ABS. The Australian Aluminium Council also compiles data on bauxite, alumina and aluminium exports, which it updates on a monthly basis.

The long-term future of Australia's aluminium industry is underpinned by vast resources of bauxite located in the Weipa (QLD) and Gove (NT) regions adjacent to the Gulf of Carpentaria 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 the north of WA currently are uneconomic to develop, but are a significant potential future resource.

In 2007 there was a slight increase in EDR to 6.2 Gt on the previous year, with some para-marginal resources being assessed as economic due largely to continued high prices. The nett change in overall Demonstrated Resources was minor because exploration drilling added to mineral resources and offset the depletion through mine production.

About 95 per cent of bauxite EDR is accessible for mining. Some areas within mining leases in the Darling Range of Western Australia in particular are not available for extraction for environmental reasons. The ratio of AEDR to current mine production shows the resource life for 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 per cent of AEDR is JORC Code ore reserves as reported by industry. The remaining AEDR represents resources assessed by Geoscience Australia as being economically recoverable from measured and indicated categories of mineral resources, as defined under the Code and other classification systems used by companies not listed on the Australian Stock Exchange. In certain terrains, the surface expression of bauxite and confidence in lateral continuity of thickness and grade make it possible to classify some inferred resources as EDR.

Data relating to exploration for bauxite specifically are not available nationally.

Australia was the leading producer of bauxite and alumina globally in 2007, and the fifth largest aluminium producer, behind China, Russia, Canada and the United States. Production totalled 62.7 Mt of bauxite (33 per cent of world production), 18.5 Mt of alumina (23 per cent of world production) and 1.954 Mt of aluminium (5 per cent of world production). Production of bauxite at Weipa in QLD during 2007 was a record 17 Mt, 5 per cent higher than in 2006, mainly due to increased production from the Andoom mine north of Weipa. Further expansion of Weipa operations south of the Embley River are under consideration, including the potential construction of a new deepwater port. Bauxite production in WA also increased 5 per cent, from 39.3 Mt in 2006 to 41.4 Mt in 2007. Production of alumina in Australia also rose by 4 per cent during 2007. The increase from 17.8 Mt to 18.5 Mt reflected capacity expansion at the Rio Tinto Alcan Gove refinery in the NT, as well as increases at the Worsley refinery in WA.

Based on USGS data for other countries, Australia's demonstrated bauxite resources of 7.9 Gt rank second in the world after Guinea and ahead of Brazil, Jamaica and China.

The 2007 Sustainability Report on Australia's bauxite, alumina and aluminium industrieswas released by Australian Aluminium Council in mid-2008. The report, which was the fourth in a series, documents how the industry is using physical resources, the impacts of that use, how industry is managing outputs and how it is working to reduce the impact of production processes.

Companies engaged in Australia's bauxite-alumina-aluminium industry continued to respond to the needs of increased trade during 2007, with further expansion proposals under consideration. The trend of aluminium industry consolidation continued in 2007 with Rio Tinto finalising its merger with Canadian aluminium producer Alcan in October. This part of the organisation is now known as Rio Tinto Alcan. Efforts by BHP Billiton since early 2007 to takeover Rio Tinto continue.

Looking to the future, alumina production levels in 2008 are not clear due to issues with WA's gas supply. A fire at the Varanus Island gas plant and consequent supply disruption led Alcoa to declare force majeure on its alumina contracts on 11 June 2008. An announcement is yet to be made on the impact to production.