Discuss the extraction of copper from copper pyrites.

Explanation

Extraction of copper fromcopper pyrites :
Copper pyrite is the main source of copper metal . Various steps involved in the extraction of copper discussed below.
Step-I
Concentration of ore by froth floatation process :
The ore is first crushed in boll mills . The finely divided ore is suspended in water. A little pine oil is added and the mixture is vigorously agitated by a current of air . The froth formed carries the ore particles almost completely. The gangue sinks to the bottom of the tank . The froth is froth is separated and about 95% Concentrated ore is obtained .
Step - II : Roasting :
To remove the volatile impurities like As (or) Sb, the roasted in a free supply of air . A mixture of sulphides of of copper and iron obtained and these are partially oxidised to respective oxides .
`Cu_(2)S.F_(2)S_(3)+O_(2)rarrCu_(2)S+2F_(e)S+SO_(2)`
`2Cu_(2)S+3O_(2)rarr2Cu_(2)O+2SO_(2)`
`2FeS+3O_(2)rarr2FeO+2SO_(2)`
Step - III
The roasted ore is mixed with a little coke and sand (Silica) and smelted in a blast furnace and fused . A blast of air , necessary for the combustion of coke, is blown through the tuyeres present at the base of the furnace. The oxidation of the sulphides of copper and iron will be complete further. A slag of iron silicate is forme according to the reactions given below :
`{:(2FeS+3O_(2)rarr2FeO+2SO_(2)),(FeO+SiO_(2)rarrFeSiO_(3)),("Ferrous Silicate (Slag)"),(Cu_(2)+FeSrarrCu_(2)S+FeO):}`
Step -IV :
After smelting the copper ore in blast furnace, the product of the blast furnace consisits mostly of `Cu_(2)S` and a little of ferrous sulphide. This product is known as "Matte." It is collected from the outlet at the bottom of the furnace. After then the following processes are carried out for getting the pure copper.
1 . Bessemerization : The matte is charged into a Bessemer converter. A bessemer converter is a pear -Shaped furnace. It is made of steel Plates. The furnace is given a basic lining with lime or magnesium oxide (obtained from dolomite or magnesite). The converter is held in position by trunnions and can be tilted in any position . A hot blast of air and sand is blown through the tuyeres present near the bottom. Molten metal, the product in the furnace, collects at the bottom of the converter.
Reactions that look place in blast furnace go to completion . Almost all of iron is eliminated as a slag. Cuprous oxide combines with cupous sulphide and Cu metal.
`2Cu_(2)O+Cu_(2)Srarr6Cu+SO_(2)`
The molten metal is cooled in sand moulds. `SO_(2)` escapes. The impure copper metal is known as "Blister Copper" and is about 98% pure .
Step -V
Refining : The Blister copper is purified by electroplysis. The impure copper metal is made intio plates. They are suspended into lead - lined tanks containing Copper (II) Suplended solution . Thin plates of pure copper serve as cathode. The cathode plates are coated with graphite . On electrolysis , pure copper is deposited at the cathode. The copper obtained is almost 100% pure Cu .
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