Aluminium block

Aluminium, more valuable than gold!


Well, to be exact, it was once more valuable that gold. It’s the third most common element in the Earth’s crust and the most abundantly available metal on Earth. It makes it hard to imagine that in the 1850s, aluminium was more valuable than gold – aluminium was priced at $1,200 per kg and gold at about half of that, $664 per kg!

So why was Aluminium so costly only about 150 years ago when there is apparently so much of the stuff? 

While about 8.8% of the Earth’s land mass is made up of the shiny silver like material,  it’s almost never found in its pure form. This has to do with aluminiums high likelihood of binding with oxygen. In nature, it is most commonly found as bauxite. Extracting aluminium from bauxite is pretty complicated (animation). And prior to the invention of the Bayer process and the Hall–Héroult process, it used to consume materials which were themselves expensive at that time.

In 1884 the Washington Monument was finalised, then the tallest structure in the world and still the world’s tallest stone structure and the world’s tallest obelisk. The very top of this tribute to America’s first president is actually n 2,8 kg. aluminium pyramidion. The largest single piece of aluminium cast at the time.

Washington Monument

Washington Monument

washington_monument_aluminum_pyramidion_lightning_rods

The aluminium pyramidion –  on the right with lightning rods installed (1934). (Photos by Theodor Horydczak)

Another great example of how the light weight metal was classified as precious during the mid- 19th century, Napoleon III gave his most distinguished guests aluminium cutlery, all other guests had to use gold or silver cutlery.

These days, aluminium has lost it’s ‘precious metal’ classification. It’s the world most recycled material and one of the few which retains all of it’s properties. Recycled it’s just a good as when it’s brand new.

This super stuff is actually not supposed to be that big of a deal at all. The metal actually oxidizes very easily, the same type of reaction that causes iron to rust and lose its properties. However, unlike flakey iron oxide, the product of this reaction, aluminium oxide, sticks to the original metal shielding it from further decay. This very thin layer (2-3 nm.) is formed when exposed to air at room temperature. Through a process called anodizing, this layer can be thickened, providing even more protection. Afterwords the anodised product or part can be dyed to give it virtually any colour. 

B-Line™ 2 poster display

B-Line™ 2 poster display – example of an anodised product

 

Interesting Aluminium facts

History

  • Ancient Greeks and Romans used aluminium compounds as an astringent, for medicinal purposes, and to dye clothes.
  • A bar of aluminium was even exhibited at the Paris Exhibition in 1855 as “the new precious metal”.
  • Sci-fi writer Jules Verne wrote about an aluminium space rocket in his novel “Journey to the Moon”.

Usage

  • Aluminium foil usually has a thickness of less than 0.2 millimetres.
  • Aluminium is almost always used as an alloy, even if the aluminium content is as high as 99%.
  • The most commonly used elements to combine with aluminium to create an alloy are zinc, copper, silicon, magnesium, and manganese.

  • Aluminium salts do not serve any known purpose in plant or animal life. 
  • It is however, not highly toxic to living organisms in small amounts.

Recycling

  • Aluminium takes only 5 percent of the energy needed to extract new aluminium from ore.
  • As of 2012, about 55 percent of aluminium drink cans made it into the recycling bin.
  • About 75 percent of all aluminium ever made is still in use, thanks to recycling, according to the Aluminium Association.

Future

 

Thanks to: Chemicool, Sam Davyson, SAPA, Softschools, Livescience, Aluminium Trade Centre.

Featured photo by Materialscientist


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