Write down the reactions taking place in different zones in the blast furnace during the extraction of iron.

Write down the reactions taking place in different zones in the blast

1.	Write down the reactions taking place in different zones in the blast furnace during the extraction of iron.
Answer» Solution :The reactions taking place in different zones of BLAST furnace are : (i) Zone of combustion : Coke burns near the tuyeres to form carbon dioxide. `C+O_(2) to CO_(2), triangleH = -393.3kJ` Temperature in this zone is around 2170K. (ii) Zone of heat absorption : Coke present in the charge reduces `CO_(2)" to "CO`. `CO_(2) +C to 2CO, triangleH = +163.2 kJ` Since this REACTION is endothermic, the temperature gradually falls to 1423K. (III) Zone of slag formation : In region, limestone decomposes to form CaO and `CO_(2.CaO` formed acts as flux and combines with SILICA to form slag. `{:(CaCO_(3) to CaO(s)+CO_(2)(g)),(CaO+SiO_(2)to CaSiO_(3)),("Calcium silicate "),("(slag) "):}` The temperature here is around 1123 K. (iv) Zone of reduction : The following reactions take place in this zone : `{:(Fe_(2)O_(3)+CO overset(823K)(to)2FeO+CO_(2)),(Fe_(3)O_(4)+CO overset(823K)(to)3FeO+CO_(2)):}` Further, reduction of `FeO" to "Fe` by CO occurs at 1123 K `FeO+CO overset(1123K)(to)Fe+CO_(2)` (v) Zone of fusion : Temperature here is in between 1423K - 1623K. Spongy iron melts and dissolves some C, S, P, Si, Mn, etc. `CaSiO_(3)` slag also metls in the region. Both the molten slag and molten iron trickle down into hearth where they form two layers. Molten slag `CaSiO_(3)` being lighter forms the upper layer while molten iron being heavioer forms the lower layer.