The world of aluminium

BAUXITE MINING AND ALUMINA PRODUCTION

Bauxite mining

Aluminium production starts with the raw material bauxite. Bauxite is a mineral found mostly in a belt around the equator. Bauxite, containing 15% to 25% aluminium, is the only ore that is used for commercial extraction of aluminium today. Global bauxite resources are estimated to be 55 to 75 billion tons and at the current rate of extraction, these reserves will last 250 to 340 years. The majority of the global bauxite reserves can be found in Australia and Africa.

Alumina production

Aluminium oxide (alumina) is extracted from bauxite in a refinery. Alumina is then used to produce primary aluminium.

PRIMARY ALUMINIUM PRODUCTION

The production of primary aluminium takes place in large production lines. In the smelting process alumina is refined into aluminium. The aluminium atom in alumina is bonded to oxygen. These bonds have to be broken by electrolysis to produce aluminium metal. Alumina is transported in large containers called pots and is dissolved in an electrolytic bath. Liquid aluminium is drawn from the cells using specialised vehicles and is cast into ingots and billets for further processing.

Aluminium is a global commodity traded on the London Metal Exchange (LME). The price moves according to global supply and demand.

CASTING OF ALUMINIUM VALUE-ADDED PRODUCTS

Aluminium casting

Primary aluminium is alloyed with other elements such as copper, manganese and silicon for additional strength, corrosion resistance and other properties. These are then cast into billets, remelt ingots, slabs, and rods and other castings for further processing.

Billet

These log-shaped castings are produced in various diameters and lengths using a vertical direct chill process. They are used for producing extrusions, also known as profiles, that find major end use in construction, industrial and transportation purposes, as well as for forging purposes in automotive industries.

Slab

These cuboid shaped ingots are the input to the rolling process and are produced using a similar technique to billet. Slab is used to produce rolled aluminium products.

Extruding

Aluminium can be extruded and shaped into a variety of tubes and profiles. Aluminium billets are heated to
500 degrees Celsius and pressed through shaping tools, to make profiles and various products.

Rolling

Aluminium can be processed in a cold and hot condition. Aluminium is ductile. Final foil products can be as thin as 0,006 mm and still be completely impermeable to light, aroma or taste. The metal itself forms a protective oxide coating that is highly corrosion resistant. Various types of surface treatment can further improve these properties.

Foundry casting

The properties of aluminium change when small quantities of other metals are added to produce aluminium alloys. These can give greater strength, brilliance, corrosion resistance and ductility, making aluminium easier to form into an endless variety of products.

Aluminium fabricated products are used throughout the world and throughout many different sectors.

In developed countries, the demand for aluminium comes mostly from the rapidly growing transport industry, that is driven by an expanding auto market. Mature countries typically use more aluminium in light vehicle production. Due to this low weight, aluminium makes cars more energy efficient.

Developing countries are expanding their infrastructure and food production to satisfy the needs of a growing population that is migrating to large cities. Consequently, the packaging and construction sectors are one of the biggest consumers of aluminium within developing countries.

RECYCLING

• Aluminium is one of the most environmentally friendly metals in terms of how it is produced and applied. It can be easily recycled, whilst keeping its distinctive properties.
• Aluminium can be endlessly recycled without loss in quality (secondary aluminium production).
• Only 5% of the energy required to produce primary aluminium is needed to remelt aluminium for new uses (secondary aluminium production).
• The world’s stock of aluminium in use is like a resource bank. Around 75% of aluminium ever produced is still in use, and some of it has been through countless recycle loops.