General Principles and Process of Isolation of Elements – Notes
Occurrence of Metals
Most metals are found in nature in a combined state owing to their high reactivity.
The only metals found in free state are Gold and Platinum.
Aluminium constitutes about 8% and Iron 5.8% by weight of the earth’s crust.
Aluminium is the 3rd most abundant element and Iron the 4th most abundant element by weight of the earth’s crust.
Naturally occurring aluminium is a major component of silicates.
Aluminium is extracted mainly from its principal ore – Bauxite.
Iron is principally extracted from its oxide ores.
Concentration of Ores
The branch of science and technology that deals with the isolation of metals from their ores is known as metallurgy.
Metals found in nature in a combined state are known as minerals.
An ore contains metal and other unwanted substances known as gangue or matrix.
The process of removing gangue from an ore is known as concentration of the ore.
Hydraulic washing is a technique used to concentrate the ore by forcing water or another liquid onto it.