Tuesday, June 14, 2011

Spiffy Material of the Indeterminate Time Period: Aluminum

Sadly, BNL never made a music video for this song, so here's their lead singer in a bathroom: http://youtu.be/9pVgj6bawus

Aluminum. It's everywhere, from around your burrito to the bodies of airplanes, but at one time, it was the most precious metal on earth. It's one of the lightest metallic elements, and one of the most abundant elements in the earth crust. So how was it so precious that Napoleon III, who used silver as his regular utensils,  gold for high ranking guests, saved his aluminum flatware for only the most honored guests? Processing.

While abundant, aluminum is almost never found in its elemental form. Aluminum almost instantly forms a thin protective oxide layer, which is what gives it such fantastic corrosion resistance. Unlike silver flatware, you don't have to regularly polish your aluminum, because the oxide layer is transparent, unlike black AgO. However, this makes extracting aluminum from its mineral forms difficult. In the early years of  aluminum processing, the Wöhler process, in which anhydrous aluminum chloride is reacted with potassium, was used. However, aluminum chloride is not the most abundant form of aluminum. 

Bauxite, made of several different forms of aluminum oxide, is the most common source of aluminum in the modern era. The Hall–Héroult process is used to extract pure aluminum, first dissolving the bauxite in molten sodium hexafluoroaluminate (also known as cryolite), and then electrolytically separating the pure aluminum from the molten salt bath. While natural cryolite was once used, reserves are largely depleted, and it is now instead synthesized from fluorite.  Fortunately, aluminum is entirely recyclable.

Take a minute to look around, and figure out everything around you that's made of aluminum, and think about how less than 200 years ago, it would have been worth more than it's weight in gold. Spiffy, huh?

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