News

16/05

2020

HOW ALUMINIUM IS MADE?

General news

Aluminium is at the heart of modern life, from the smartphone in your hand, to the plane you fly in, to the buildings where you live and work. As economies grow and living standards rise, industry experts expect that demand for aluminium will increase. But have you ever wondered how aluminium is made?

Some facts:

• Aluminium was first produced in 1850 by a French alchemist and technologist called Henri-Etienne Sainte-Claire Deville. 

• After iron, aluminium is the second most-used metal in the world.

• After oxygen and silicon, aluminium is the third most abundant element in the earth’s crust.

• In Europe, after transport (39%), construction at 24% is the second largest application. 

• In 2012, on average, each European citizen used 22kg of aluminium 

• China is the largest producer of aluminium

• 90% of all aluminium recovered from demolition/end-of-life is recycled. 

 

Aluminium production process starting from Bauxite

Step 1: Bauxite Mining
The production process for aluminium starts with the mining of bauxite ore. Layers of bauxite are generally found near the surface so it is extracted through open cast mining. Around 90% of the world’s resources are in tropical & sub-tropical regions. Bauxite is a mixture of aluminium hydroxide, iron oxide, titanium dioxide and kaolinite. Large deposits of bauxite occur in Australia, Brazil, Guinea and Jamaica and the primary mining areas for the ore are in China (top producer), Australia, Brazil, India, Guinea, Indonesia, Jamaica, Russia and Suriname.

Step 2: Alumina Refining
Bauxite is refined into alumina using the Bayer process. Two or three tonnes of bauxite are required to produce one tonne of alumina. In the digestion stage, hot caustic acid is added to the bauxite to dissolve the aluminium bearing minerals in the bauxite. Clarification separates bauxite solids from the pregnant liquor via sedimentation. In the precipitation stage, alumina crystals are recovered from the liquor via crystallization. Calcination is a roasting process to remove the remaining water.

Step 3: Aluminium Smelting
Alumina is smelted into aluminum using the Hall-Heroult process. It takes two tonnes of alumina to produce one tonne of aluminium. Alumina is poured into special reduction cells called pots with an electrolytic bath of molten salt called cryolite at temperatures around 960 degrees Celsius. An electrical current is then projected into the mixture at 400KA or above. This current then breaks the bonds between aluminium and oxygen atoms in alumina, resulting in liquid aluminum settling at the bottom of the reduction cell.

Step 4: Casting
Aluminium is then transferred to the cast house, where it is made into products using several different methods. Alloys are added into many of products, according to customer specifications, before the solidification stage. In re-melt casting aluminum, at a temperature of 700 degree Celsius, is poured into moulds. The moulds are cooled and the aluminium solidified before being packed and shipped to the customer. 

 

Video clip below from EGA explaining the process of producing Aluminium from Bauxite!

 

Source: greenspec.co.uk ; Emirates Global Aluminium