In 1889, recent college grad Charles Martin Hall devised a way to isolate metallic aluminum. __1889: __ Charles Martin Hall patents his process for using electrical current to extract metallic aluminum from its raw ore.
Aluminum is the most abundant metallic element in the Earth's crust,1 but not as a pure metal. Bauxite -- a mixture of hydrated aluminum oxides -- accounts for 99 percent of it. Aluminum metal wasn't known until work by Humphry Davy in Britain, Hans Ørsted in Denmark and Friedrich Wöhler in Germany successfully isolated it the 19th century.
As a metal, aluminum is strong, lightweight, ductile, malleable, shiny and resistant to corrosion. It's also easy to combine with other metals in ways that increase its desirable properties.
Wöhler's process passed an electrical current through a water solution of aluminum salt, but it yielded aluminum hydroxide that required further refinement into metal. That made the exotic "new" metal very costly, used only for jewelry and special, ceremonial applications like capping the Washington Monument.
Hall, fresh out of Oberlin College in 1886, tried dissolving the aluminum salt in a fused-cryolite (sodium aluminum fluoride) bath instead of water. Voilà: metallic aluminum. Hall needed money to scale up the process, and he eventually got it from the Pittsburgh's Mellon Bank, founding a company that would become the Aluminum Company of America, now Alcoa.
The fame of Hall may be more than his due alone. Charles Hall's sister Julia Brainerd Hall also was a major contributor on both the scientific and business fronts. What's more, Paul Héroult independently developed the same refinement process in France the same year as Hall.
The Hall process (sometimes called the Hall-Héroult process) has made aluminum available for widespread use in aviation, construction, kitchenware, beer kegs, cooking foil and myriad other uses. The price of aluminum metal dropped from $32 a pound in the 1850s ($730 in today's money) to $15 a pound before the Hall process ($340 today) to 18 cents a pound in 1914 (about $3.75). The aluminum market is subject to market fluctuations, but it's increased from 50 cents a pound to more than a dollar in the last 15 years.
Variants of the Hall process are still in use today, and require between 6.5 and 9.0 kilowatt-hours of electrical energy to produce a pound of aluminum. That's why recycling aluminum uses 95 percent less energy than making it from ore. A recycled can saves enough electricity to light a 100-watt bulb for up to 3½ hours.
(Source: Various)
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