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Revision: Class 12 >> General Principles and Processes of Isolation of Elements NEET (UG) General Principles and Processes of Isolation of Elements

Definitions [13]

Definition: Ores

At some places, minerals contain a very high percentage of a particular metal, and the metal can be profitably extracted from it. These minerals are called ores.

Ores are those minerals from which metals are extracted commercially at a comparatively lower cost and with minimum effort.

Definition: Minerals

The elements or compounds, which occur naturally in the earth’s crust, are known as minerals.

Minerals are the naturally occuring compounds of metals which are generally mixed with other substances such as soil, mud, sand, silica (Si02) limestone, rocks, etc. These earthly impurities are called gangue or matrix.

Definition: Metallurgy

The science and technology regarding the extraction of metals from ores and their purification for the use is called metallurgy.

Define the term : Ore

Ore: Those minerals from which a metal can be extracted profitably are called ores.

Define the term : Charge

Charge: The mixture of materials fed into a furnace to extract a metal is called charge.

Define the term : Mineral

Mineral: The naturally occurring compounds of metals which are generally mixed with earthy such as soil, sand, limestone and rocks are known as minerals.

Define the following term.

Gangue

The impurities (sand, silt, soil, gravel, etc.) present in the ore are called gangue.

Define roasting.

Roasting is the process of heating concentrated ore to a high temperature in the presence of air. The process is usually carried out for sulphide ores.

Define the term:

Slag

The product obtained by the combination of gangue with flux is called slag.

Define the term:

Flux

The substance added to get rid of gangue in the extraction of metal is called flux.

Define calcination.

If an ore is a carbonate or a hydrated oxide, it is heated in the absence of air to a temperature that is high but insufficient to melt the ore. The process is known as calcination.

Define the Ore.

Minerals from which metals can be extracted profitably are known as ores.

If minerals contain a very high percentage of a particular metal and the metal can be profitably extracted from it. These minerals are called ores.

Define the following term.

Mineral

Most of the elements occur in nature as in combined state as minerals. The chemical composition of minerals is fixed.

Key Points

Key Points: Occurrence of Metals

Metals occur in either the free or combined state, depending on their reactivity.
Metals are grouped as low, medium, or highly reactive, and each group has a different extraction method.
Ores have impurities called gangue, which are removed before extraction.
Low-reactive metals are extracted by heating alone; medium-reactive metals require roasting or calcination, followed by reduction.
Highly reactive metals (such as Na, Mg, and Al) are extracted by electrolysis.
Metals are purified by electrolytic refining, where pure metal deposits at the cathode and impurities form anode mud.

Key Points: Metallurgy

Reactive metals occur in combined form (as oxides, sulphides, etc.), while unreactive metals like gold and silver occur in the free state.
Minerals are natural metal compounds; those from which metals can be extracted economically are called ores, and impurities present in ores are called gangue.
The complete process of extracting and purifying metals from ores is called metallurgy.

Key Points: Extraction of Metals

Highly reactive metals like Na, K, and Al are extracted by electrolysis of their molten salts.
Aluminium is extracted from bauxite using leaching and electrolysis.
Cryolite and fluorspar help lower the melting point of alumina during extraction.
Moderately reactive metals like Zn and Fe are extracted by roasting or calcination, then reduced with carbon or aluminium.
Less reactive metals like gold and silver are found in the free state and extracted by heating.

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