aluminum
Aluminum is the third most abundant element in the Earth's crust and was probably formed during the birth of our solar system through collisions of hydrogen atoms under intense heat and pressure. Aluminum never occurs as a metal in nature and is only found in the form of its compounds, such as alumina, because of its strong affinity with oxygen. It is this special bond for oxygen that explains why it withstood all attempts to prepare it in its elemental form until well into the nineteenth century.The aluminum industry was founded in 1854, but it was not until the late 1880's that a method was found to bring down the prices and permit aluminum to be used in a wide variety of ways. Most of the aluminum in the w
Agitation causes the crystal to cling to each other as they slowly begin to fall to the bottom of the vat. The final step is to drive off the remaining moisture by passing the alumina, which now looks like white mud, through kilns that heat it to more than 1000 deg C (1830 deg F). When it is dry, and about 99 percent pure, it is stored in silos, ready for the next process that turns the alumina into aluminum. This next step is called the Hall-Heroult process. Most of these large Bauxite deposits are found in the tropical and the subtropical climates, where heavy rainfall, warm temperatures, and good drainage combine to encourage the weathering process. It is here that the alumina crystals begin to form. In these tanks, which are injected with steam, the alumina is turned into a creamy slurry and poured into a settling tank. It was formed by the weathering of aluminous rocks such as feldspar, nepheline, and clays. After the extraction of the Bauxite, it must be converted to Alumina by the Bayer Process, a process patented in 1888 and is still used today. This process begins when bauxite is smashed by being mixed with soda ash and lime in a ball mill. They are then subject to cleansing by the same ash and lime solution that was added at the beginning of the process. In these tanks, the heavier metals and sand sink to the bottom, while the alumina remains on top. During the weathering, these rocks are decomposed and leached out, leaving behind a residue of ore rich in alumina, iron oxide, and silica. Because Bauxite is usually found near the surface, it is mined by open-pit methods.
Common topics in this essay:
Bayer Process,
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Baux France,
ash lime,
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