Chemistry Minerals and Ores
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### Topics Covered :

● Introduction
● Minerals and Ores
● Occurrence of Ores

### Introduction :

=> A few elements like carbon, sulphur, gold and noble gases occur in free state while others in combined forms in the earth’s crust.

=> The extraction and isolation of an element from its combined form involves various principles of chemistry.

=> A particular element may occur in a variety of compounds.

=> The process of metallurgy and isolation should be such that it is chemically feasible and commercially viable.

=> Some general principles are common to all the extraction processes of metals.

text(Minerals :) These are naturally occurring chemical substances in the earth’s crust obtainable by mining.

text(Ores :) Minerals in which a metal may be found, only a few are viable to be used as sources of that metal. Such minerals are known as ores.

=> Rarely, an ore contains only a desired substance. It is usually contaminated with earthly or undesired materials known as text(gangue).

=> The extraction and isolation of metals from ores involve the following major steps :

• Concentration of the ore

• Isolation of the metal from its concentrated ore and

• Purification of the metal.

text(Metallurgy :) The entire scientific and technological process used for isolation of the metal from its ores is known as metallurgy.

### Occurrence of Metals :

=> Elements vary in abundance.

text(Aluminium :)

●Among metals, aluminium is the most abundant.

● 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 Al_2O_3 and the impurities range from Cr (in ‘ruby’) to Co (in ‘sapphire’).

text(Iron :)

● 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.

=> The principal ores of aluminium, iron, copper and zinc have been given in Table1.

=> For the purpose of extraction, bauxite is chosen for aluminium.

=> For iron, usually the oxide ores which are abundant and do not produce polluting gases (like SO_2 that is produced in case of iron pyrites) are taken.

=> For copper and zinc, any of the listed ores (Table1) may be used depending upon availability and other relevant factors.

=> Before proceeding for concentration, ores are graded and crushed to reasonable size.