Mastering Chemistry Help: May 2012

Copper is extracted from its principal ore copper pyrites (CuFeS₂). The ore is concentrated by froth flotation process. The concentrated ore is roasted in a reverberatory furnace when the following reactions occur.
1. The volatiles like sulphur and arsenic escape as gases

S + O₂ --------------> SO₂ 4AS + 3O₂ --------------->2AS₂O₃

2. Copper pyrites is converted to a mixture of Cu₂S and FeS

2CuFeS₂ + O₂ ---------------> Cu₂S + 2FeS + SO₂

3. The sulphides of Cu and Fe are partially oxidized

2Cu₂S + 3O₂ <=======> 2Cu₂O + 2SO₂

2FeS + 3O₂ <========> 2FeO + 2SO₂

Smelting in extraction of copper

The roasted ore mixed with silica as flux is heated in a blast furnace by a blast of hot air. Most of the FeO is removed as a slag and a molten mixture of Cu₂S and FeS called matte, get collected in the hearth of the furnace.

FeO + SiO₂ -----------> FeSiO₃
gangue + flux ------------> Slag

Bessemerisation in extraction of copper

The molten matte (CU₂S + FeS) is transferred to a Bessemer converter, a pear shaped vessel lined with MgO or SiO₂ and heated by hot air blown through tuyers and mounted in such a way that it can be filled in any direction. It is mixed with some silica as flux and heated by passing hot air through tuyers.
The air oxidises FeS to FeO, which combine with silica forming a slag.

2FeS + 3O₂ --------------> 2FeO + 2SO₂

FeO + SiO₂ --------------> FeSiO₃

The blast of air is continued when excess silica is absorbed by the basic lining (MgO) of the converter. Cuprous sulphide is partially oxidised by air to cuprous oxide which then combine with the remaining cuprous sulphide to form copper.

2Cu₂S + 3O₂ -----------> 2Cu₂O + 2SO₂

Cu₂S + 2Cu₂O -----------> 6Cu + SO₂

The molten copper is poured out and allowed to cool. The sulphur dioxide escaping from the melt gets trapped in the cooler parts of the surface giving a blistery appearance for copper and hence it is called blister copper. Blister copper is further refined by poling and electrolytic method, as described in the refining of metals. The air oxidises FeS to FeO, which combine with silica forming a slag.

2FeS + 3O₂ --------------> 2FeO + 2SO₂

FeO + SiO₂ --------------> FeSiO₃

The blast of air is continued when excess silica is absorbed by the basic lining (MgO) of the converter. Cuprous sulphide is partially oxidised by air to cuprous oxide which then combine with the remaining cuprous sulphide to form copper.

2Cu₂S + 3O₂ -----------> 2Cu₂O + 2SO₂

Cu₂S + 2Cu₂O -----------> 6Cu + SO₂

The molten copper is poured out and allowed to cool. The sulphur dioxide escaping from the melt gets trapped in the cooler parts of the surface giving a blistery appearance for copper and hence it is called blister copper. Blister copper is further refined by poling and electrolytic method, as described in the refining of metals.

related articles extraction of aluminum
extraction of sulphur

The chemical properties of alcohols and phenols are mainly due to the presence of the hydroxyl functional group. The presence of the aromatic benzene ring provides some characteristic chemical reactions for phenols.
The reactions of -OH groups in alcohols and phenols may be divided into two classes.
1. Reaction involving cleavage of O-H bond
and
2. Reaction involving cleavage of carbon - oxygen (C-O) bond
The reaction involving cleavage of O-H bond consist of
1. Reaction with Metals
2. Reaction with alkali
3. Reaction with carboxylic acids (Esterification)

The reaction involving cleavage of carbon - oxygen (C-O) bond consist of
1. Reaction with hydrogen halides
2. Reaction with phosphorus halides and SOCl₂
3. Dehydration
4. Oxidation
5. Dehydrogenation