A few elements like carbon, sulphur, gold and noble gases, occur in free state while others are found in combined forms in the earth’s crust. Elements vary in abundance. Among metals, aluminium is the most abundant. In fact, it is the third most abundant element in earth’s crust (8.3% approx. by weight). It is a major component of many igneous minerals including mica and clays. Many gemstones are impure forms of Al₂O₃. For example, gems ‘ruby’ and ‘sapphire’ have Cr and Co respectively as impurity. Iron is the second most abundant metal in the earth’s crust. It forms a variety of compounds and their various uses make it a very important element. It is one of the essential elements in biological systems as well.

For obtaining a particular metal, first we look for minerals which are naturally occurring chemical substances in the earth’s crust and are obtained through mining. Out of many minerals in which a metal may be found, only a few are viable to be used as source of that metal. Such minerals are known as ores.

Which of the following is a ore of tin?

Cassiterite

The correct answer is option 2. Cassiterite.

Certainly! Cassiterite \((SnO_2)\) is the primary ore of tin. Here's a detailed explanation of cassiterite and its significance in tin extraction:

Composition and Properties:

Cassiterite is a tin oxide mineral composed of tin (Sn) and oxygen (O). Its chemical formula is \(SnO_2\). It typically appears as brown or black crystals or granular masses. The color may vary depending on impurities present in the mineral. Cassiterite has a high specific gravity, making it relatively heavy compared to many other minerals. This property is often exploited in its separation from lighter gangue minerals during ore processing.

Occurrence:

Cassiterite is commonly found in association with granite, pegmatite, and other igneous rocks. It forms as a result of hydrothermal or magmatic processes. Significant cassiterite deposits are found in countries like China, Indonesia, Bolivia, Myanmar, and Brazil, among others.

Extraction of Tin:

Tin is extracted from cassiterite through a series of processes, which may vary depending on the ore grade and the presence of impurities. However, the general steps involved in tin extraction from cassiterite include:

Mining: Cassiterite-bearing ores are mined from underground or open-pit mines.

Concentration: The mined ore is crushed and ground to liberate the cassiterite particles from the gangue minerals. Gravity separation techniques, such as jigging or shaking tables, are commonly used to concentrate cassiterite due to its high specific gravity.

Flotation: In some cases, flotation may be employed to further concentrate the cassiterite concentrate and remove impurities.

Smelting: The concentrated cassiterite is then smelted in a furnace with carbon (usually in the form of coal or coke) to reduce the tin oxide to metallic tin. This process typically occurs at high temperatures in the presence of a flux to facilitate the removal of impurities.

Refining: The crude tin obtained from smelting may undergo further refining processes, such as electrolytic refining or fractional distillation, to obtain high-purity tin suitable for various industrial applications.

In summary, cassiterite is the primary ore of tin and is crucial for the production of tin metal. Tin extraction from cassiterite involves mining, concentration, smelting, and refining processes to obtain pure tin metal for use in various industries, including electronics, soldering, and coating applications.