Occurrence and extraction of copper form copper pyrites

Copper occurs both in combined state and free state. It also contains many ores. The important ores of copper are copper pyrites (CuFeS₂), cuprite and copper glance. The copper ores are mostly found in the north of India.

Extraction

The extraction of copper also involves many steps. The ore used for extraction is copper pyrites. This ore is crushed, concentrated and then heated in the presence of air. During heating the moisture gets expelled and the copper pyrites gets converted to ferrous sulphide and cuprous sulphide.

Blast furnace is used to heat the mixture of roasted ore, powdered coke and sand. In the blast furnace oxidation reactions takes place.

Ferrous sulphide forms ferrous oxide which combines with silica and forms the slag.

Cuprous sulphide forms cuprous oxide which is partially converted to cuprous sulphide.

This cuprous sulphide contains some amount of ferrous sulphide and this is called matte. Matte is removed from the base outlet of blast furnace. The removed matte is shifted into Bessemer converter which is lined inside with magnesium oxide. This converter has pipes through which hot air and SiO₂are sent in. In this converter Cu₂S converts to Cu₂O and FeS converts to FeO. The ferrous oxide forms slag with SiO₂. The cuprous oxide formed reacts with Cu₂S and forms copper.

The copper thus formed is to be purified by electrolysis.