ALUMINA REFINING
The aluminium industry relies on the Bayer process (Link: http://www.world-aluminium.org/) to produce alumina from bauxite. It remains the most economic means of obtaining alumina, which in turn is used for the production of aluminium metal – around two tonnes of alumina are required to produce one tonne of aluminium.
Related Link: www.world-aluminium.org/
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SMELTING
The production process known as electrolytic reduction, enabling aluminium to become one of the world’s most widely-used metals. The electrolysis takes place in a steel vessel called a cell. The cell, maintained at a temperature of about 965°C, is lined with carbon and contains a melt or electrolyte of molten cryolite. Carbon blocks are suspended above the cell and partially immersed in the electrolyte to act as anodes while the carbon lining of the cell acts as a cathode.
Alumina is fed into the electrolyte and separates into positively charged ions of aluminium and negatively charged ions of oxygen. Direct current applied across each cell moves the ions in opposite directions. The oxygen rises to the anode where it burns the carbon to form carbon dioxide. The molten aluminium settles at the bottom of the cell where, at regular intervals, it is extracted – or tapped – using a vacuum crucible.
To sustain the electrolytic process, alumina is fed into the cells continuously. The raw materials required to produce 1 tonne of aluminium are 1.9 tonnes of alumina; 418kg of carbon (a blend of petroleum coke and pitch) and 17.5kg of aluminium fluoride.
Related Link: www.world-aluminium.org
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PROCESSES
Aluminium is such a versatile metal, it can be processed in many different ways depending on the application required. Aluminium can be alloyed with other materials to make an array of metals with different properties. The main alloying ingredients are iron, silicon, zinc, copper, magnesium and manganese.
Related Link: www.world-aluminium.org
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Extruding
Aluminium can be extruded to form intricate shapes and sections. It is heated to around 500°C and pushed through a die at great pressure.
Aluminium extrusions are used in commercial and domestic buildings for window and door frame systems, prefabricated houses/building structures, roofing and exterior cladding, curtain walling, shop fronts, etc. Furthermore, extrusions are also used in mass transportation for airframes, road and rail vehicles and in marine applications.
Related Link: http://eaa.net/en/
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Forged
Aluminium can be forged by hammering to make stress-bearing parts for aircraft and internal combustion engines.
Related Link: www.aluminium.org/
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Cast
Aluminium can be cast into and infinite variety of shapes.
Related Link: www.aluminium.org/
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Rolled
Aluminium can be rolled into plate, sheets, or wafer thin foils the thickness of human hair. The rolling process changes the characteristics of the metal, making it less brittle and more ductile.
Rolled products are used in home appliances, packaging and transportation, building & construction and many other applications.
Related Link: http://eaa.net/en/
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Fine Aluminium products
Aluminium powder, flake and paste can be formed by lowing gas under pressure at molten aluminium. This process forms droplets of different sizes. These aluminium products are used in explosives, rocket fuel, metallurgy, chemicals, inks and decorative materials.
Related Link: www.aluminium.org/
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Cables
Aluminium has high electrical conductors, and its light weight and good resistance to corrosion make it ideal for overhead electrical transmissions and distribution cable as well as for power systems and substations.
Related Link: www.aluminium.org/
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