Metals have always played a crucial role in human life. These materials are of such importance that the stone age saw a sharp rise in metallic elements to make weapons, utensils, statues, jewellery, etc. Even though iron, copper, bronze and brass were the most common metallic compounds in early civilization, later on, aluminium gained more importance. Its physical and chemical properties make it ideal for heat applications, lightweight construction, higher durability and strength requirements and more. The most striking fact about aluminium is that it can be used as a standalone metal or in the form of alloys. This is why it has been able to replace several other elements in various industries.

Occurrence of aluminium

Since aluminium is highly reactive, it is not present in a free state. Instead, it occurs in a compounded form where the atoms also stay in combination with other elements. For example, bauxite is the aluminium ore where metal combines with oxygen. Therefore, no physical stress of the metal will be available in nature, no matter where the source is.

Following are the major countries where aluminium is produced in bulk:

1. China: 3.7 million
2. Russia: 3.6 million
3. India: 3.6 million
4. Australia: 1.6 million
5. Norway: 1.4 million

Metallurgic extraction of aluminium

Since bauxite has the maximum aluminium concentration, it is considered to be metallic ore. The following steps are followed for the extraction of metals:

1. First, bauxite is subjected to a series of hydrating reactions, forming aluminium oxide. Here, the aluminium density is low, so this silvery-white powder is sometimes separated for several purposes.
2. As aluminium has a high melting point, it is not molten for electrolysis. Instead, cryolite is used (an aluminium compound with a lower melting point and will allow the ions to move freely within the electrolytic cell).

iii. The cathode and anodes are made with graphite since they can transfer heat faster.

1. With the electrolytic reactions, crude aluminium will be deposited on the anode (negative terminal of the cell) while the cathode needs to be replaced gradually.

Physical properties of aluminium

The aluminium formula as per the periodic table is ‘Al’. In the free state, it appears to be silvery-white in colour, which sets it apart from steel (alloys of iron). Following are some of the physical properties of this metallic component:

2. Density: 2.6989 g/cm3 (might differ by +/-2% based on the alloys)
3. Tensile strength: 45 Nm-2 (pure aluminium) and 90 Nm-2 (commercial aluminium)

iii. Melting temperature: 660.2 ℃

1. Boiling point: 2470 ℃
2. Thermal conductivity: 235 W/Km

Owing to the low aluminium density, it is very light and has applications in several aspects. Besides, it is temperature tolerant and won’t melt quickly. Owing to its high tensile strength, it can be made into sheets and thin ropes.

Top compounds of aluminium

The major compounds that can be made with aluminium are:

1. Aluminium oxide: This is one of the most abundantly available molecules having the aluminium metal. Even though oxygen can react with the metal, the aluminium oxide layer will form on the surface as a hard crust. Therefore, further reactions will be stopped.
2. Aluminium sulphate: This compound is used in the paper industry to bind the dye molecules on the paper surfaces and fill up the surface pores.
3. Alum is a conjugated compound where aluminium sulphate is combined with water molecules and potassium sulphate. This has several medicinal properties and also stops bleeding.
4. Aluminium chloride is used as a catalyst in the Friedel Crafts reaction, where organic compounds are formed.

Alloys made with aluminium and their application

Many alloys can be formed with the help of aluminium. We have discussed some of the essential compounds in the following section.

 Advantages of using aluminium

• Aluminium is used to construct lightweight products because it has less density and is much lighter than other elements.
• It is cheaper and therefore has replaced copper in electrical wires.
• Aluminium has tensile strength, so it can be used to make tough ropes like the ones used for hanging elevators.
• Another significant advantage of using aluminium is its resistance to oxidation reactions.

Conclusion

Aluminium is one of the highly demanded elements, thanks to its physical and chemical properties and the availability of alloys. These alloys are used extensively in almost all industries, like making aircraft and ships, thin aluminium coils for rockets or launchers, etc. Therefore, with the growing demand for the metal, countries face intense pressure to extract pure metal for ores, refine them, and then transform them into the desired shape. The main problem is in the metallic extraction because, unlike other metals that can be separated from their ore through oxidation reactions, aluminium has to be extracted through electrolysis. Thus, scientists continue their studies to find a more feasible solution so that the demand and supply chain can be met easily.