Name: Metal Displacement Reactions
Uploaded: 2019-07-19
Duration: 9 min 12 s
Description: This video describes the displacement reactions based on the reactivity series in which a more reactive element displaces a less reactive one from its aqueou...

Question

Explain the smelting process.

Accepted Answer

Smelting (in a Blast Furnace): The charge consisting of roasted ore, coke and limestone in the ratio $8 : 4 : 1$ is smelted in a blast furnace by introducing it through the cup and cone arrangement at the top. There are three important regions in the furnace.

(a) The Lower Region (Combustion Zone): The temperature is at $1500 ° C$ . In this region, coke bums with oxygen to form ${CO}_{2}$ when the charge comes in contact with a hot blast of air.

$C + O_{2} \to_{∆}^{1500 ° C} {CO}_{2} + Heat$
It is an exothermic reaction since heat is liberated.

(b) The Middle Region (Fusion Zone): The temperature prevails at $1000 ° C$ . In this region, ${CO}_{2}$ is reduced to $CO$ .

${CO}_{2} + C \to_{∆}^{1000 ° C} 2 CO - Heat$

Limestone decomposes to calcium oxide and ${CO}_{2}$

_{${CaCO}_{3} \underset{\nabla}{\to} CaO + {CO}_{2} - Heat$}

These two reactions are endothermic due to absorption of heat. Calcium oxide combines with silica to form calcium silicate slag.

$CaO + {SiO}_{2} \to {CaSiO}_{3}$

(c) The Upper Region (Reduction Zone): The temperature prevails at $400 ° C$ . In this region, carbon monoxide reduces ferric oxide to form a fairly pure spongy iron.

${Fe}_{2} O_{3} + 3 CO \overset{400 ° C}{\to} 2 Fe + 3 {CO}_{2}$

The molten iron is collected at the bottom of the furnace after removing the slag.
The iron thus formed is called pig iron. It is remelted and cast into different moulds. This iron is called cast iron.

Explain the smelting process.

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