Where does aluminum come from?

Aluminum is both lightweight and strong, so it's no wonder that space stations, airplanes and thousands of other products use this metal. But where does it come from, and what makes it so special? Tune in to learn more.

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Episode Transcript

Speaker 1 (00:00):
Welcome to Brainstuff from house Stuff Works dot com where
smart Happens. Hi Am Marshall Brain with today's question, where
does aluminium come from? Our modern world would not be
possible without aluminium. It's a metal that's both lightweight and strong.

(00:24):
Aluminum is the primary metal used in all modern passenger
jets in the air today. The same is true of
the Space Shuttle in the International Space Station. They wouldn't
be even possible without aluminum. Cars often contain aluminum in
the form of rims and engine blocks. We also find
aluminum around the house in the form of beer canned
aluminum foil, frying pans, bicycles, and folding lawn chairs. The

(00:49):
biggest advantage of aluminum is it's lightweight when compared to
something like steel. If you have a cube made of
steel that weighs three pounds, the same sized cube of
aluminum will weigh just over one pound. The aluminum will
not be as strong as steel, but when an aluminum
structure is engineered to have the same strength as a

(01:09):
steel structure, the aluminum structure might weigh one third less.
This explains why aluminum is so popular and things like
airplanes and spacecraft and even cars to a greater degree today.
Another advantage for aluminum is its natural corrosion resistance. When
it gets wet, steel rusts, especially if it's not painted.

(01:31):
Aluminum doesn't rust. An airplane can fly without any paint
if so desired, and that saves even more weight. However,
aluminum is more expensive than steel. Pound for pound, aluminum
can cost three or four times more than steel. It's
true that you don't need as much aluminum as you
do steel to reach the same strength, but aluminum still

(01:52):
costs more. That's why most cars today are made of steel.
A steel car body might cost half as much as
an aluminium car body. The reason why aluminum costs more
is because of the way it's made. An aluminum factory
starts the production process with a mind rock called box site.
Box site is crushed and treated with chemicals to remove

(02:15):
the impurities, and what's left after processing is alumina, also
known as aluminum oxide. To make aluminum, you have to
take the oxygen out of alumina, so the illumina is
put in a large graphite lined vessel with a chemical
called cryolite. Huge amounts of electricity, heat and separate the

(02:37):
aluminum atoms. This is why aluminum factories are often located
near hydroelectric power plants and other sources of cheap electricity,
and it also explains why aluminum is expensive. It takes
about six kilowatt hours of electricity to make one pound
of aluminum from box site. When you consider that a
homeowner typically pays ten cents per kilowatt hour for a electricity,

(03:01):
you can get a sense of the effect of that
electricity on the cost of aluminum. Just the electricity represents
a significant cost, not to mention the cost of the
box site itself, it's transportation, and the other chemicals and
equipment needed to make aluminium. For this a reason, aluminium
costs more than a dollar per pound in bulk right now. Historically, however,

(03:22):
aluminum is now quite inexpensive. Before the invention in eighteen
six of the process used today to make aluminum, it
was extremely difficult and time consuming to create aluminum from
or When they capped the Washington Monument in eighteen eighty four,
they used a small aluminum pyramid weighing about six pounds.

(03:46):
At the time, aluminum cost about one dollar per ounce
in today's dollars. That means that a pound of aluminum
in the eighteen eighty four cost about three dollars. The
cost of aluminum to day is an credible bargain compared
to that. Today, the stealing cars is in the process
of being replaced by aluminum. Lighter cars use less gasoline,

(04:09):
and as gas gets more expensive, aluminum makes more sense.
Aluminum hoods are not uncommon today. The Toyota Prius is
said to have one, and that one piece can shave
as much as twenty pounds off the weight of the car. Meanwhile,
aluminum airplanes are heading toward carbon fiber. This transition is
not happening quite as quickly because carbon fiber is so

(04:32):
new and and tested in large things like airplanes. Boeing
seven seven Dreamliner will be the first mostly carbon commercial
passenger jet to take to the skies. For more on
this and thousands of other topics, does that house stop
works dot com and don't forget to check out the
brainstuff blog on the house stop works dot com home page.

(04:52):
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