To make aluminum, you first have to dissolve your bauxite in a vat of molten
cryolite (1,012 °C/1,854 °F, which is less than aluminum's 2000C melting
temp.) Then, you have to use electrolysis at only 3V, but using a tremendous
220 kA to 340 kA. Then, the aluminum precipitate that gathers on the cathode
must be continuously siphoned to draw the aluminum (in a liquid state) out
of the mixture and through a series of high temperature valves and pumps to
a location where it can be cast into ingots.
The technology to do each step requires a highly industrialized economy,
which is why it was so rare in historical times, even though Aluminum makes
up 8% of the earth, by weight.
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