Electrical Components

When Kings Preferred Aluminum To Gold

30 November 2017

Today we tend to take aluminum for granted because of its ubiquity. It’s hard to really appreciate the value of a metal we use every day for so many disposable applications. This has led to misconceptions, such as that titanium is lighter than aluminum, or that aluminum has a rather dull grayish appearance when in fact it has a shiny silver luster when polished. When asked, many people will say we recycle aluminum cans to protect the environment when in fact we do it to greatly reduce the cost of aluminum production. Aluminum is not often thought of as a modern material though it wasn’t discovered until the 19th century and wasn’t mass produced until the 20th century using a process requiring electricity. In a way, aluminum’s reputation has become a victim of its enormous success and versatility.

After silicon and oxygen, aluminum is the third most abundant element found in the Earth’s crust. It is perhaps surprising then that pure aluminum was a relatively rare and valuable metal until the 20th century. In the mid-1800s aluminum was a precious metal on par with silver and gold. Proof of this can be found at the apex of the Washington monument, the capstone, which is made of aluminum and was cast in Philadelphia and displayed at Tiffany’s in New York before being installed on the monument in 1884. Aluminum was exhibited at the Exposition Universelle of 1855 in France and aluminum utensils were used by Napolean III for favored guests and gold for everyone else.

Aluminum cans being cleaned and prepared at a recycling facility.Aluminum cans being cleaned and prepared at a recycling facility.Aluminum salts had been used in ancient Egypt, Greece and Rome for a variety of purposes such as reducing the turbidity of water, helping dyes adhere to clothing and helping bandages stop bleeding, etc. One common class of these salts was referred to as alum, from which our modern name for the metal derives. Although these salts were well known, it wasn’t until 1825 that Hans Christian Oersted from Denmark succeeded in producing the first aluminum alloy containing pure aluminum. Friedrich Woehler, a German chemist who built upon Oersted’s work, was able to create small balls of solidified molten aluminum in 1845, a process that was later industrialized in 1856 by Henri-Etienne Sainte-Claire Deville.

Aluminum at this time was expensive to produce and was treated like a precious metal, used in jewelry and other adornments. However the lightweight, malleable metal was already recognized for its potential applications. In 1865, Jules Verne described an aluminum space rocket in his novel, Journey to the Moon. More practical applications included lighter ships and trains that would allow for faster, more fuel-efficient transport. The only barrier to the widespread use of Aluminum was the cost of production.

In 1886, Charles Hall and Paul Heroult independently developed an inexpensive electrolysis process by which aluminum could be extracted from alumina. Austrian engineer Karl Josef Bayer developed a chemical process by which alumina can be extracted from bauxite, a widespread and naturally occurring aluminum ore in 1889. The combination of the two processes made it possible for the first time to mass produce pure aluminum at a fraction of the cost. Both the Bayer and Hall-Heroult processes are still used today to produce nearly all the world’s aluminum.

The Hall-Heroult process required a large amount of electricity to power the electrolytic process. Charles Hall established the Pittsburgh Reduction Company in 1888 and soon built smelters in New York near the new Niagara hydroelectric power station. In 1907 the company was reorganized and renamed the Aluminum Company of America, or more commonly known as Alcoa. This time period, the late 1800s to the early 1900s marked aluminum’s transition from a precious metal to an industrial raw material. Alcoa went from producing 25 kilograms of aluminum a day in 1888 to 41,000 kilograms of aluminum a day in 1909.

Demand for aluminum grew as manufacturers learned how the material could improve their products performance and the cost of production came down. In addition, new industries emerged that couldn’t have existed without the material. In 1903, the Wright brothers used aluminum to make the engine crankcase for their first wood-frame biplane. The airframe of a typical modern commercial transport aircraft is 80 percent aluminum by weight. Aluminum alloys are the overwhelming choice for the fuselage, wing and supporting structures of commercial airliners and military cargo/transport aircraft.

In 1910 aluminum foil entered the food packaging market. As aluminum alloys were developed, the metal's properties improved and soon it was being used for everything from conducting wires to pots and pans to skyscrapers. All metal airplanes were developed in 1915 using aluminum alloys and it wasn’t long before the demands of mechanized warfare in World War I had greatly increased aluminum production. By World War II aluminum production was so essential it was a strategic priority. It was during WWII that aluminum recycling gained traction as it reduced the cost of production.

After the war aluminum production was through the roof and companies were ready to exploit the excess demand. Aluminum cans became widespread for storing food and beverages, preferred because they didn’t impart any flavor like tin cans did. Bicycles, house siding, wires, recreational boats, just about everything integrated aluminum. Recycling became essential for the economics of production. Today Americans throw away one billion dollars of aluminum every year. The aluminum industry pays 800 million dollars a year for recycled cans.

Today, through improved production and recycling efforts, aluminum is relatively cheap and widely used. This is remarkable considering how difficult it is to produce. The ubiquity of aluminum is a direct result of its useful properties, from its electrical conductivity which makes it useful to electronics, to its thermal conductivity which makes it ideal for fast cooling pots and pans, to its light weight which makes it ideal for fuel economy in trains, planes and automobiles. In our modern times we all get excited about the possibilities of carbon nanotubes and titanium, and these materials do hold tremendous promise, but we should occasionally stop to appreciate the wonder material that makes every aspect of our lives better: aluminum.

To contact the author of this article, email roger.pink@ieeeglobalspec.com

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