Occurrence of Aluminum

Aluminium is present in igneous rocks as aluminosilicates in feldspars, feldspathoids, and micas; as clay in the soil formed from these rocks; and as bauxite and iron-rich laterite following further weathering. The primary source of aluminium is bauxite, which is a mixture of hydrated aluminium oxides. Emery (corundum) is a crystalline aluminium oxide that occurs naturally in a few igneous rocks and is mined for its abrasive properties or in finer forms as rubies and sapphires. Topaz, garnet, and chrysoberyl are gemstones that contain aluminium. Alunite and cryolite are two other aluminium minerals with economic use.

Before 5000 BCE, people in Mesopotamia were producing exquisite pottery from an aluminium compound clay, while Egyptians and Babylonians employed aluminium compounds in different chemicals and medicines around 4,000 years ago. Pliny is referring to alumen, which today is known as alum, an aluminium compound that was frequently employed in the ancient world to set colours in garments. In the second part of the 18th century, chemists such as Antoine Lavoisier recognised alumina as a viable metal source. When electricity became more accessible and affordable, Charles Martin Hall in the United States and Paul-Louis-Toussaint Héroult in France discovered almost simultaneously (1886) the modern method of commercially producing aluminium: electrolysis of purified alumina (Al2O3) dissolved in molten cryolite (Na3AlF6). Aluminium surpassed copper as the world’s top producer of nonferrous metals in the 1960s.

Occurrence

Aluminium is the third most prevalent element in the earth’s crust, making it the most abundant metal, accounting for 7.57 per cent of the oxygen and silicon in the earth’s crust by weight. Due to the nature of its foundation, it appears virtually exclusively in bound form. The majority is chemically bonded in the form of aluminosilicates, where it takes the position of silicon in oxygen tetrahedra. These silicates are found in clay, gneiss, and granite, among other places.

Alumina is very seldom found in the mineral corundum or its variants ruby (red) and sapphire (colourless, of different colours). The hues of these crystals are due to the presence of various metal oxides in their composition. Corundum contains the largest amount of aluminium of any compound at over 53%. Aluminium is also found in large concentrations in the even rarer minerals Akdalait (about 51%) and Diaoyudaoit (approximately 51%). (about 50 per cent). There are now 1156 aluminium-containing minerals identified.

Bauxite is the sole commercially significant raw material for aluminium manufacture. South France (Les Baux), Guinea, Bosnia and Herzegovina, Hungary, Russia, India, Jamaica, Australia, Brazil, and the United States all have deposits. Bauxite is composed of around 60% aluminium hydroxide (Al (OH)3 and AlO (OH)), as well as 30% iron oxide (Fe2O3) and silica (SiO2).

In manufacturing, primary aluminium, also known as metallurgical aluminium, is obtained from bauxite, whereas secondary aluminium is obtained from aluminium scrap. Recycling consumes around 5% of the energy used in initial manufacturing.

Aluminium Ores

Aluminium is a highly reactive metal that is part of the periodic table’s IIIA group. Aluminium is present in nature in the form of its oxide in its ores. The primary aluminium ores are as follows:

• Bauxite – Al2O3.2H2O

• Corundum – Al2O3

• Cryolite – Na3AlF6

Compounds

Generally, aluminium is trivalent. At elevated temperatures, however, a few gaseous monovalent and bivalent molecules have been synthesised (AlCl, Al2O, AlO). Aluminium’s three outer electrons are configured in such a way that the bare ion, Al3+, created by their loss is known to occur in a few compounds (e.g., crystalline aluminium fluoride [AlF3] and aluminium chloride [AlCl3]).

Due to the high energy required to generate the Al3+ ion, it is typically more energy efficient for the aluminium atom to form covalent compounds via sp2 hybridization, as boron does. Hydration has the ability to stabilise the Al3+ ion, and the octahedral ion [Al(H2O)6]3+ is found in an aqueous solution and a variety of salts.

Numerous aluminium compounds are employed in a variety of different sectors. Alumina, which occurs naturally as corundum, is also bulk manufactured in massive quantities for use in aluminium metal, insulators, and spark plugs, among other goods. When heated, alumina forms a porous aluminium structure that allows it to absorb water vapour. This form of aluminium oxide, referred to in the industry as activated alumina, is used to dry gases and liquids. Additionally, it serves as a carrier for a variety of chemical reaction catalysts.

Aluminium’s Applications

The following is a list of aluminium’s applications.

1. Aluminium is utilised in a broad variety of applications in the transportation and construction industries.

2. Aluminium foil is used to wrap food in the food industry.

3. This metal dust is used in paints.

4. It is used to separate manganese and chromium oxides.

5. Because it is a malleable metal that can be shaped into any shape, it is used to manufacture storage cans.

6. Aluminium is the second most often used metal, behind iron.

7. It is most frequently used in combination with another metal in an alloy, which means that it is combined with another metal to make another compound with desired properties, such as stainless steel.

Feldspathoids

The feldspathoids are a type of tectosilicate minerals that are structurally similar to feldspars but contain significantly less silica. They are found in uncommon and peculiar forms of igneous rocks and are seldom found in primary quartz-containing rocks. The Red Hill Syenite is a remarkable outlier since it contains both feldspathoids and quartz-bearing rocks. Foid, a contraction of feldspathoid, is a word that refers to any igneous rock that contains up to 60% modal feldspathoid minerals. For instance, a syenite containing a considerable amount of nepheline might be referred to as a nepheline-bearing syenite or nepheline syenite, with the name nepheline being interchangeable with any other foid mineral. The Streckeisen (QAPF) classification of igneous rocks uses this nomenclature.

Feldspathoid minerals

• Afghanite – Mineral composed of tectosilicates

• Analcime – Mineral composed of tectosilicates

• Cancrinite – A mineral composed of feldspathoids

• Kalsilite – A vitreous feldspathoid mineral ranging in colour from white to grey

• Leucite – Mineral composed of potassium and aluminium tectosilicates

• Nepheline — Aluminosilicate mineral composed mostly of silica.

• Petalite – A silicate mineral that is utilised in the glazing of ceramics.

• Sodalite Group 

• Hauyne

• Lazurite – Mineral composed of tectosilicates and a member of the sodalite group

• Nosean

• Sodalite – A tectosilicate mineral that is blue in colour.

• Tugtupite

Conclusion

Aluminium occurs mostly as aluminosilicates in feldspars, feldspathoids, and micas; as clay in the soil formed from them; and as bauxite and iron-rich laterite with further weathering. The primary source of aluminium is bauxite, a combination of hydrated aluminium oxides.