How is Aluminium extracted from earth and how Aluminium ingots are produced?

After oxygen and silicon, aluminium is the third's most abundant element. It forms approximately 8% of the earth's crust. Because it bonds easily with other elements so it is never found in its original form. It is generally present as oxides with bauxite being its most popular and viable resource.rnExtraction of aluminium from bauxite usually happens by a chemical process followed by electrolysis. The first step is called as Bayer's refining process. This process was discovered by Karl Bayer, an Austrian chemist, in 1888.Under this process bauxite is first crushed and grounded to powdered form. Then it is mixed with hot solution of caustic soda and pressure heated in a digester (steam-heated unit).Under pressure, caustic soda melts aluminum oxide to solution form called as sodium aluminate. Impurities like oxides of silicon, lead and iron remain in solid form and can easily be removed by filtration. Finally liquid sodium aluminate is added in precipitator with contains small amount of pure and fine alumina hydrate. As the solution cools the sodium aluminate precipitates around the fine alumina hydrate. Then by settling and vacuum filtering this solid is separated from caustic soda. This solid crystal is then washed, dried and heated at high temperature to remove any liquor. As a result of this process we now get white powdery aluminium oxide also known as alumina. The process of extracting aluminium from aluminium oxide is called as Hall-Heroult smelting. In this process aluminium is extracted from aluminia by electrolysis. In electrolysis, two metal electrodes are submerged in liquid containing positive and negative ions. One electrode is positively charged(called anode) while the other one is negatively charged(called cathode).Since like charges repel and opposite charges attract ,positive charged ions present in the liquid are attracted to cathode and negative charged ions are attracted to anode. In aluminum smelting process, the electrolyte is placed in an iron vat called as pot which is lined with graphite. This pot act as cathode. Carbon is immersed in electrolyte which acts as anode. Aluminia is dissolved in synthetic cryolite at a very high temperature of 1,000 degrees C to form a molten solution. Though the melting point of pure alumina is 2054 C but mixing it with cryolite allows the electrolysis to occur at lesser temperatures. Electricity is passed though this molten material which causes the oxygen from the aluminum oxide to combine with the carbon of the anode forming carbon dioxide gas. Aluminium attracts to cathode so it collects at bottom of the pot. This aluminium is collected periodically from the bottom through a plug. Aluminum manufacturers can use this molten aluminium to form fabricated or foundry ingots.rn1) Fabricated ingots -For this, molten aluminum is transferred to furnaces where it is mixed with other metals to form alloys. It is then cleaned using gases like nitrogen or argon to remove impurities. This process is called as fluxing .After this molten metal is poured into moulds and cooled to form fabricated ingots. 2. Foundry ingots-Some of the aluminium from the pots is directly poured into mounds .This molten aluminium solidifies on cooling to form foundry or remelt ingots. Aluminum suppliers can sell these remelt ingots to foundries where aluminium is again melted, alloyed and fluxed and made into various forms and shapes. For more information visit http://www.aluminiumglobalsuppliers.com