What is Aluminum?- Properties, Uses & How It’s Made

What is Aluminum?

Aluminum is a chemical element with the atomic number 13 and the symbol Al. In the boron group, it is a silvery-white, soft, nonmagnetic, and ductile metal. Aluminum is the most prevalent metal and the third most abundant element in the earth’s crust after oxygen and silicon. It accounts for 8.1 percent of the crust’s weight and 6.3 percent of its atoms.

Aluminum is only found in a wide variety of earthy and rocky minerals, including feldspar, mica, granite, and clay since it is a very active metal. Kaolin is a fine, white aluminum-containing clay used in porcelain production.

Aluminum oxide, often known as alumina, is used to lining furnaces and does not melt until temperatures reach 3632°F (2000°C). Corundum and emery are two more hard forms of alumina utilized as abrasives.

Several semiprecious gemstones, such as garnet (Fe3 Al2 Si3 O12), beryl (Be3 Al2 Si6 O18), ruby and sapphire, Al2 O3 having chromium and iron impurities, are among the many different mineral forms in which aluminum may be found. In lasers, manufactured rubies and sapphires are employed.

Aluminum is a chemical element with the atomic number 13 and the symbol Al. In the boron group, it is a silvery-white, soft, nonmagnetic, and ductile metal.
Courtesy: earth.com

History of Aluminum:

Aluminum is the third most plentiful element in the earth’s crust, accounting for more than 7% of its mass. It only exists in nature in very stable compounds with other materials, and its existence was not discovered until 1808. It took years of research to separate the metal from its ore and develop a commercially feasible production technique.

Sir Humphrey Davy was the first to discover and name aluminum, which he did in 1808. Near the village of Les Baux in southern France, P. Berthier discovered a hard, reddish, clay-like soil containing almost 50% aluminum oxide in 1821. It’s called bauxite, and it’s the most common aluminum resource.

Hans Oersted of Denmark created modest quantities of aluminum metal in 1825 by reacting dilute potassium amalgam with aluminum chloride and distilling the resultant mercury away to leave a slightly impure aluminum deposit.

Aluminum metal was still incredibly expensive to produce in any amount, and it remained a rare and valuable metal for a long time. Aluminum was selling for almost $545 per pound in 1852.

In 1886, Charles M. Hall and Paul L-T. Heroult independently created what is now known as the Hall or Hall-Heroult procedure. It involves dissolving alumina in melted cryolite, a common aluminum-containing mineral, and conducting an electric current through the heated liquid.

Electrolysis is a process that collects molten aluminum metal at the cathode (negative electrode). The price of aluminum metal fell to roughly 30 cents per pound not long after this technique was developed.

Ores of Aluminum:

Aluminum belongs to the IIIA group of the periodic table and is a highly reactive metal. Aluminum is found in the form of oxide in its ores in nature. The most important aluminum ores are:

  1. Bauxite – Al2O3.2H2O
  2. Corundum – Al2O3
  3. Cryolite – Na3AlF6

Manufacturing Process of Aluminum

1. The Bayer Process:

Bauxite, an ore containing aluminum oxide, iron, and other metals, is used to make aluminum. The Bayer process is used for bauxite after being mined, and it is named after the Austrian chemist who invented it in the late 1800s.

Aluminum oxide must be recovered from bauxite before it can be utilized for any industrial purpose because it must be isolated from any surrounding impurities before it can be processed. The bauxite is placed in a chemical solution and heated between 150 and 200 degrees Celsius to dissolve the aluminum oxide in the first stage of the Bayer process.

2. The Hall—Heroult Process:

The Hall—Heroult technique, named after the American and French chemists who invented it separately in 1886, was then used to manufacture aluminum. It is still widely used today, with very slight changes. Aluminum oxide must be processed into pure aluminum before being utilized in manufacturing since it contains oxygen atoms.

The refinement process begins with the heated aluminum oxide crystals being placed in a vat of molten cryolite, which quickly dissolves the crystals and forms an electrolyte solution. The vat is then filled with a direct current that enters through a carbon lining and exits through a pair of carbon rods.

The aluminum complex, in liquid form, passes through a series of filters before settling in a precipitation tank, where it begins to crystallize. The crystals are then fired in a kiln at around 1,100° C, yielding pure aluminum oxide. The electric current starts a chemical process that separates the aluminum from the oxygen atoms and causes it to collect at the bottom of the vat.

After going through this procedure, aluminum becomes molten metal with a purity of 99.8%. After that, the molten metal can be cast into a mold, cooled with water, and finished to the desired shape. As a result, industrial-grade aluminum is produced.

Properties of Aluminum:

Physical Properties of Aluminum:

  • Aluminum is a silvery-white metal with no odor or taste. With the addition of silicon, the material becomes more malleable and soft. The cubic structure of the aluminum crystal is face-centered.
  • Aluminum has a lower density than any other commercial metal except for magnesium. When it has the correct surface type, aluminum is an excellent reflector, especially for UV light.
  • The creation of impurity segregations causes the lattice to concentrate in the less pure metal. Most other physical attributes are influenced by purity.
  • Aluminum can also be used as a cold or hot selective wall or as a body that simulates the impression of a black body. Aluminum’s reflectance in the infrared range is slightly higher than gold and silver.
  • Except for magnesium, Aluminium has a lower density than any other commercial metal.

Chemical Properties of Aluminum:

  • Because the surface of aluminum metal is covered with an oxide layer that shields the coating from air attack, it does not react with it. When the oxide layer is destroyed, the aluminum metal is exposed, which combines with oxygen and aids in developing amphoteric oxide (Aluminium (III) Oxide), Al2O3.

4Al(s) + 3O2 (l) → 2Al2O3 (s)

  • Mineral acids react with Aluminium to produce solutions containing the liquid AI (III) ion and hydrogen gas, H2. Aluminum reacts with HCl to produce hydrogen gas.

2Al(s) + 6HCl (aq) → 2Al3+ (aq) + 6Cl– (aq) + 3H(g)

  • This reaction results in the release of hydrogen gas (H2). When Aluminium combines with a heated sodium hydroxide solution to form a colorless sodium tetra hydroxoaluminate solution with the release of hydrogen gas, the Aluminium can form covalent bonds with oxygen.

2Al (s) + 2NaOH (aq) + 6H2O → 2Na(aq) + 2[Al (OH)4] + 3H(g)

Mechanical Properties of Aluminum:

  • Aluminum can withstand significant deformation without breaking. Rolling, extruding, drawing, machining, and other mechanical operations can now be used to shape Aluminium. It can also be cast with a high degree of precision.
  • Aluminum characteristics can be tailored by alloying, cold working, and heat treatment.
  • The tensile strength of pure Aluminium is roughly 90 MPa, while some heat-treatable alloys can reach over 690 MPa.

Uses of Aluminum:

  • Aluminum and its alloys have a variety of applications, including the following:
  • Aluminum is utilized in electrical transmission lines because it is a good conductor of electricity.
  • Poles, tubes, pipes, plates, wires, and foils are all shaped with aluminum
  • Because of its sturdiness and lightweight, it was utilized to create kitchenware in factories, planes, and other autos.
  • Air conditioners and solar conductors both use it.
  • It’s also widely utilized in bridges, ladders, wires, and doors, among other things.
  • Silver foil is used for packaging chocolates and other items.

Advantages of Aluminum:

  • Aluminum has a specific weight of 2.7 g/cm3, about one-third that of steel. Aluminum production expenses are reduced. Its application in cars saves dead weight and energy while boosting load capacity. It also lowers noise levels and increases comfort.
  • Aluminum naturally produces a thin oxide covering that protects the metal from further interaction with the environment. Aluminum alloys are less corrosion resistant than pure Aluminium except for marine magnesium-aluminum alloys.
  • Aluminum is a good conductor of heat and electricity. As a result, aluminum has become the preferred material for major power transmission lines.
  • Aluminum is a good heat and visible light reflector, which, along with its lightweight, makes it a suitable material for reflectors in,
  • Aluminum has a low melting point and density and is ductile. In a molten state, it can be treated in various ways.
  • Aluminum is completely recyclable, and recycled aluminum has the same properties as new aluminum. As a result, it’s a considerably more cost-effective source material for large-scale production runs.

Disadvantages of Aluminum:

  •  Compared to other materials, such as steel, aluminum is more expensive.
  • Welding aluminum involves special procedures, which might be costly and take longer than other methods.
  • While aluminum is malleable, this feature can also be a negative. In comparison to steel, it is more easily dented and scratched.

Conclusion:

Aluminum is the most common metal on Earth, accounting for more than 8% of the planet’s core mass. After oxygen and silicon, it’s the third most common chemical element on the earth. Alumina is found in various products, including cans, foils, cooking utensils, window frames, beer kegs, and aircraft parts.

Despite its disadvantages, there is no doubt that aluminum will become even more commonly employed in the construction sector as the need for structures that are flexible, easy to maintain, and inexpensive in cost-of-use develops.

References:

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  • What Is Aluminum? • Earth.com. (2020, September 29). Earth.Com; www.earth.com. https://www.earth.com/earthpedia-articles/aluminum/
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