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Explain extraction of : (i) Copper from Copper(I) Oxide (ii) Zinc from zinc oxide. |
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Answer» Solution :(i) Extraction of copper from Cu(I) oxide : In the Ellingham diagram, the `Cu_2O` line is almost at the top. Hence, it is QUITE easy to reduce oxide ores of copper directly to the metal by heating with coke. The lines `(C, CO) and (C, CO_2)` are at much lower positions in the GRAPH particularly after 500 - 600 K. However, many of the ores are sulphides and some may also contain iron. The sulphide ores are roasted/smelted to give oxides. `2Cu_2S + 3O_2 to 2Cu_2O + 2SO_2` The oxide can then be easily reduced to metallic copper using coke : `Cu_2O + C to 2Cu + CO` In ACTUAL process, the ore is heated in a reverberatory furnace after mixing with silica. In the furnace, iron oxide .slags of. asiron silicate is formed. Copper is produced in the form of copper matte. This contains `Cu_2S` and FeS `FeO + SiO_2 to underset(("Slag"))(FeSiO_3)` Copper matte is then charged into silica LINED convertor. Some silica is also added and hot air blast is blown to convert the remaining `Fes, FeO and Cu_2S//Cu_2O`to the metallic copper. `2FeS + 3O_2 to 2FeO = 2SO_2` `FeO + SiO_2 to FeSiO_3` `{:(2Cu_2S + 3O_2 , to , 2Cu_2O + 2SO_2),(2Cu_2O + Cu_2S , to , 6Cu + SO_2):}}` Auto reduction Process The solidified copper obtained has blistered appearance due to the evolution of `SO_2` and so it is called Blister Copper. (ii) Extraction of zinc from zinc oxide : The reduction of zinc oxide is done using coke. The temperature in this case is higher than that in the case of copper. For this purpose of heating, the oxide is made into brickettes with coke and clay. `ZnO + C underset("1673 K")overset("Coke")(rarr) Zn + CO` The metal is distilled off and collected by rapid chilling. |
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