Aluminium :: essays research papers

Aluminium The history of Aluminium use Aluminium is now one of the most widely used metals, but one of the hardest to refine due to it's reactivity with other elements. Even as late as the turn of the century, Aluminium was considered very valuable and in turn expensive, even more expensive than gold. In some cultures, when a function was held (for example, a party) by wealthy people, only the most honored guests would be given Aluminium cutlery, the others had to make do with gold or silver cutlery. A Description of the Aluminium ore, including a list of it's contents Pure Aluminium oxide is known as alumina (Al2O3). This is found as corundum, a crystalline. Aluminium can also occur as cryolite (Na3AlF6). Traces of other metal oxides in Aluminium oxide tint it to make it form stones (often precious) for example: chronium gives a red colour to rubies, and cobalt makes the blue in sapphires. How Aluminium deposits are formed Aluminium (like many other metals) is not found in it's pure form, but associated with other elements in rocks and minerals. An aluminosilicate such as felspar (KAlSi3O8) is the main constituent of many rocks such as granite, which is quartz and mica cemented together with felspar. These rocks are gradually weathered and broken down by the action of carbon-dioxide from the air dissolved in rainwater forming ‘kaolin'. This is further broken down to form other substances, ultimately resulting in the formation of Aluminium deposits. Where and how Aluminium is mined? Aluminium is never found in it's pure state until it has been refined. Aluminium is made when refining alumina, which is in turn found from the ore ‘bauxite'. Bauxite is often mined in the opencast method. Aluminium deposits are found in many countries, but the countries with significant deposits include: Guinea, Jamaica, Surinam, Australia and Russia. How is Aluminium refined? One method is the ‘electrolytic process'. This is performed when a low voltage current is passes through a bath containing alumina in the molten form. The alumina is broken down into Aluminium metal which collects at the bottom of the bath at one electrical pole, the cathode, and the oxygen which reacts at the other pole, the anode, to give carbon-dioxide and some carbon-monoxide. The uses and properties of Aluminium Aluminium is now the second most widely used metal, after iron.