Image taken from http://www.azom.com/work/C58Z456fioS0Fovf1py0_files/image003.jpg
Image taken from http://www.azom.com/work/C58Z456fioS0Fovf1py0_files/image003.jpg

THE ALUMINIUM FOILS

The aluminium foils used in the packaging of the Lagundi tablets are taken from the earth's crust and follow the processes shown above. Generally the technologies are described below:

  1. Bauxite mining - Bauxite ore is mined from different areas of the world. Among the areas where bauxite is extracted are Australia, Central and South America (Jamaica, Brazil, Surinam, Venezuela and Guyana), Africa (Guinea), Asia (India, China), CIS and parts of Europe (Greece and Hungary).
  2. Alumina Production - the raw material for primary aluminium production is alumina (aluminium oxide) which is extracted from bauxite. The website www.azom.com described the extraction process as follows: "Bauxite has to be processed into pure aluminium oxide (alumina) before it can be converted to aluminium by electrolysis. This is achieved through the use of the Bayer chemical process in alumina refineries. The aluminium oxide is released from the other substances in bauxite in a caustic soda solution, which is filtered to remove all insoluble particles. The aluminium hydroxide is then precipitated from the soda solution, washed and dried while the soda solution is recycled. After calcination, the end-product, aluminium oxide (Al2O3), is a fine grained white powder."
  3. Primary Aluminium Production through electrolysis, - This process is again described by the website www.azom.com as follows: "Primary aluminium is produced in reduction plants (or "smelters"), where pure aluminium is extracted from alumina. The reduction of alumina into liquid aluminium is operated at around 950 degrees Celsius in a fluorinated bath under high intensity electrical current. This process takes place in electrolytic cells (or “pots”), where carbon cathodes form the bottom of the pot and act as the negative electrode. Anodes (positive electrodes) are held at the top of the pot and are consumed during the process when they react with the oxygen coming from the alumina. At regular intervals, molten aluminium tapped from the pots is transported to the cast house where it is alloyed in holding furnaces by the addition of other metals (according to the user’s needs), cleaned of oxides and gases, and then cast into ingots."
  4. Semi-Fabrication - This encompasses several industrial processes: rolling, casting and extrusion . Azom describes the whole process:
  • Rolled products, i.e. sheet, plate and foil constitute almost 50 % of all aluminium alloys used. In North America and Western Europe, the packaging industry consumes the majority of the sheet and foil for making beverage cans, foil containers and foil wrapping. Sheet is also used extensively in building for roofing and siding, in mass transport for airframes, road and rail vehicles, in marine applications, including offshore platforms, and superstructures and hulls of boats. Plate is used for airframes, military vehicles and bridges, ship superstructures, cryogenic and chemical vessels and as tooling plate for the production of plastic products. Foil applications outside packaging include electrical equipment, insulation for buildings, lithographic plate and foil for heat exchangers.
  • Aluminium casting processes are classified as ingot casting or mould casting. During the first process, primary or aluminium is cast into rolling ingot (slab), extrusion ingot (billet) and wire bar ingot which are subsequently transformed in semi- and finished products. The second process is used in the foundries for producing cast products. This is the oldest and simplest mean of manufacturing shaped components. Aluminium castings are very powerful and versatile techniques for manufacturing semi- or finished products with intricate shapes. Those techniques are continuously improved and developed to satisfy the user needs and to penetrate new markets.
  • The term extrusion is usually applied to both the process, and the product obtained, when a hot cylindrical billet of aluminium is pushed through a shaped die. The resulting section can be used in long lengths or cut into short parts for use in structures, vehicles or components. Also, extrusions are used for the starting stock for drawn rod, cold extruded and forged products.

  • Product Manufacture - Aluminium is then formed into products. The aluminium unique combination of properties has enabled designers and manufacturers to develop products that enhance the quality of life. Many applications in transportation, medicine, food preservation and electricity distribution would not have been possible if a material with aluminium’s high strength-to-weight characteristic, outstanding barrier properties, good conductivity and corrosion resistance had not been available.


References:

Aluminium and Aluminium Alloys - Life Cycle of Aluminium - http://www.azom.com/Details.asp?ArticleID=3529