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प्रश्न
Name the sulphide ore of Copper. Describe how pure copper is extracted from this ore.
उत्तर
The sulphide ore of copper is copper pyrite (CuFeS2). The extraction of pine copper from copper pyrite ore involves the following steps.
1. Crushing and grinding
2. Concentration by the froth-floatation process to remove gangue particles.
3. Roasting in the presence of free supply of air or O2 during roasting the reactions taking place are
\[\ce{S + O2 ->[\Delta] SO2}\]
\[\ce{P4+5O2->[\Delta] P4O10}\]
\[\ce{4As +3O2 ->[\Delta]As4O6}\]
\[\ce{2CuFeS2 +O2 ->[\Delta] Cu2S +2FeS +SO2}\]
\[\ce{2feS + 3O2 ->[\Delta]2FeO + 2SO2}\]
The roasted ore mainly contains a number of Cu2S, FeS, and FeO.
4. Smelting: The roasted ore is mixed with powdered coke and sand and is heated strongly in a blast furnace.
\[\ce{2Fe + 3O2 ->[\Delta] 2FeO + SO2}\]
\[\ce{FeO +\underset{\text{(Flux)}}{SiO2}->\underset{\text{Ferrous silicate}(Slag)}{FeSiO3}}\]
The mixture thus obtained contains Cu2S and some FeS. It is called the molten matte.
5. Bessemerisation: In Bessemer converter, a hot blast of air mixed with sand is blown through molten matte. The reactions taking place are:
\[\ce{2FeS + 3O2->[\Delta] 2FeO + 2SO2}\]
\[\ce{FeO + Sio2->[\Delta]FeSiO3}\]
\[\ce{S + O2 ->[\Delta]SO2}\]
\[\ce{4As+3O2->[\Delta]As4O6}\]
\[\ce{2Cu2S + 3O2->[\Delta]2Cu2O + 2SO2}\]
\[\ce{2Cu2O+Cu2S->[\Delta]\underset{\text{Molten Copper}}{6Cu}+SO2}\]
On cooling molten copper, we get blister copper.
6. Refining of Copper: The copper obtained above is refined by poling and then by electrolyte refining containing acidified copper sulphate solution as an electrolyte.
