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Explain smelting process . |
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Answer» Solution :Smelting ( in a Blast Furnance ) : (i) The charge consisting of roasted ore, cok and limestone in the ratio 8:1 . (ii) Smelted in a blast furnanceby introducingit through the CUP and cone arrangement at the top. Thereare three important regions in the furnance.  (a) The Lower Region (Combustion Zone ) : (i) The temperatureis at `1500^(@)C`. Coke burnswith oxygento form `CO_2` whenthe chargecomesin contact with a hot blastof air . `C+O_2 underset(Delta)overset(1500^(@)C) to CO_2 +"Heat"` It is an exothermic reaction since heat is liberated . (b) The MiddleRegion ( Fusion Zone ) : (iii) The temperatureprevailsat ` 1000^(@)C`. (iv) `CO_2` is reduced to ` CO` `CO_2+C underset(Delta)overset(1000^(@)C)to2CO+"Heat"` Limestone decomposes to calcium oxide and `CO_2`. `CaCO_3underset(Delta)toCO_2+"Heat"` (V) These TWO reactions are endothermicdue to absorption of heat . (vi) Calcium oxide combineswith silicato form calciumsilicate slag. `CaO+SiO_2 to CaSiO_2` (c) The Upper Region ( Reduction Zone ) : (i) The temperatureprevailsat ` 400^(@)` C . (ii) Carbonmonoxide reduces ferric oxide to form a fairly PURE spongy IRON. `Fe_2O_3+3CO overset(400^(@)C) to 2Fe+3CO_2` The molten iron is collectedat the bottom of the furnanceafter removingthe slag . (iii) The iron thus formed is called pig iron. (iv) It'sremelted and cast into different moulds. This iron is called cast iron. |
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