Bauxite and Aluminium

At a Glance

• Ore Bauxite, a laterite rock
• Process Bayer process then Hall–Héroult electrolysis
• Ratio About 4 to 6 tonnes of bauxite per tonne of aluminium
• India’s lead state Odisha
• Smelter location Near cheap power
• Exam link UPSC Prelims, Geography: Mineral and Energy Resources

Where Does It Fit?

This is the sixth topic of the macro on mineral and energy resources and the first of the non-ferrous metals. The previous topic covered unconventional gas, and this one covers aluminium’s ore. The next topic covers lead, zinc and pyrites. Previous topic: Unconventional Gas – Coalbed Methane, Shale Gas and Tight Gas. Next topic: Lead, Zinc and Pyrites.

What Is Bauxite, and How Is Aluminium Made?

In short: bauxite is refined to alumina, and alumina is smelted into aluminium with very large amounts of electricity.

1. Formation: bauxite forms in tropical regions with heavy rain, where weathering removes silica and leaves aluminium oxides near the surface, so it is mined in open pits and is often found on plateau tops and with laterite, as in Major Soil Groups of India.
2. Refining: in the Bayer process the crushed bauxite is dissolved in hot caustic soda to give alumina, aluminium oxide, leaving a red mud residue. About two tonnes of alumina come from four tonnes of bauxite.
3. Smelting: in the Hall–Héroult process alumina dissolved in molten cryolite is split by an electric current into aluminium metal. About two tonnes of alumina give one tonne of aluminium, and the smelting uses about 13,000 to 15,000 kilowatt-hours of electricity per tonne.

Because the power cost is the largest cost, smelters are located near cheap electricity, such as coal-based power plants, hydroelectric dams or captive power, and not always near the bauxite, as in Factors Influencing Industrial Location. Aluminium is light, strong when alloyed, a good conductor and can be recycled repeatedly with only about five per cent of the energy of primary production. Its main uses are in transport, including aircraft, railway coaches and cars, in building frames, in electric power cables, in packaging such as cans and foil, and in cookware. The red mud left over from refining is a strongly alkaline waste that must be stored in lined ponds, and its disposal is a major environmental issue around refineries such as Lanjigarh and Damanjodi.

Where Is Bauxite Found?

India has bauxite reserves of about 3.9 billion tonnes and annual production of the order of 20 to 25 million tonnes in recent years, mostly mined in Odisha, with Gujarat and Jharkhand next. Most of the output is used in the country for alumina and aluminium, with small amounts exported, as in Mining and Quarrying.

Where Are the Alumina Refineries and Smelters of India?

India is among the largest producers of aluminium in the world, with output of about four million tonnes of primary aluminium a year, but China produces more than half of the world’s total. As an analytical point, aluminium is a case of an industry where power, not the ore, decides the site, so India’s smelters have been built on the coalfields of the eastern plateau and use captive coal power. Future competitiveness depends on cheaper renewable power, low-carbon aluminium for export markets with carbon border rules, and recycling.

Why Is This Topic Important?

• Process Bayer and Hall–Héroult asked
• Location Power-based smelters
• Map Smelters and mines

What Came Next?

The next topic describes lead, zinc and pyrites. Next topic: Lead, Zinc and Pyrites.

Key People and Terms

• Bauxite Aluminium ore
• Alumina Aluminium oxide
• Bayer process Refining bauxite to alumina
• Hall–Héroult process Electrolytic smelting
• Red mud Refining waste
• Cryolite Flux in smelting

Exam Corner

Mains Angle

Questions ask why aluminium plants are where they are. These points add depth.

• Ore Tropical weathering
• Power Dominant cost
• Future Low-carbon supply