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Composition of copper matte is.A. `Cu_(2) S + FeS` (small amount)B. `Cu_(2) S + FeS` (small amount)C. `Cu_(2)+ FeSO_(4)` (small amount)D. `Cu_(2)S + FeO` (small amount) |
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Answer» Correct Answer - A `underset((A)) (2CuFeS_(2) + O_(2)) overset ("Roasting") rarr Cu_(2)S + 2FeS + SO_(2)` `Cu_(2) S` and `FeS` are further partially oxidised. `2Cu_(2) S + 3O_(2) rarr 2Cu_(2) O + 2SO_(2)` `2FeS + 3O_(2) rarr 2FeO + 2SO_(2)` At iron is more reactive than copper, `FeS` is preferentially oxidised to `FeO` than `Cu_(2)S` to `Cu_(2)O`. If at all any `Cu_(2)O` is formed, it reacts with `FeS` to give `Cu_(2) S` again. `Cu_(2)O + FeS rarr Cu_(2) S + FeO` Hence, `(B)` and `( C)` are `FeO` and `Cu_(2)S`. On smelting `(B) + (C)`, i.e., heating with `SiO_(2)` (flux) and soem powdered coke, `FeO` combines with silica to form fusible ferrous silicate slag. `FeO +SiO_(2) rarr underset("Ferrous silicate (slag)")(FeSiO_(3))` Slag being lighter, floats on the lower layer which comprises of copper matte. Copper matte mainly consists of `Cu_(2) S` and some unchanged `FeS`. Copper matte is separated from slag, and on electrolysis gives pure `Cu` metal. Hence, Copper matte is `Cu_(2) S + FeS` (small amount) . |
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