Aluminum is one of the poor metals that is a silver colored solid in its natural state. Aluminum has an atomic weight of 26.9815386, a melting point of 1220.58 °F, and a boiling point of 4566 °F. Aluminum is the most abundant metal in the Earth’s crust, and it is used for a variety of purposes. Some of the more common uses of aluminum include: as a powder in the composition of paints, pyrotechnics, and thermites, as a solid for construction of transportation vehicles, and in the manufacture of cooking utensils.
Aluminum is a highly reactive metal and so it is not found free in nature. While different isolation processes are possible, only a few are used due to energy costs.
The largest source for aluminum that is used for large scale commercial isolation is from bauxite. Bauxite is a type of ore that is striped mined because of its large aluminum content. The process which is used to isolate aluminum from bauxite is called the Bayer process. During this process, the bauxite ore is combined with sodium hydroxide and heated under pressure to approximately 392 °F. The result is a solution which contains sodium aluminate and sodium silicate. In the next step of the Bayer process, carbon dioxide is run through the solution resulting in a precipitate of aluminum hydroxide. The aluminum hydroxide is then filtered, washed, and heated to form alumina, (Al2O3). The final step used to separate pure aluminum from alumina is performed by using electrolysis. To minimize the energy that is needed for the electrolysis step, carbon lined steel cells are used as the cathodes and anodes for this reaction.
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