Name: Reduction of Metal Oxides
Uploaded: 2019-07-19
Duration: 4 min 4 s
Description: Copper is the third most industrially consumed metal in the world. Its unique properties make it very special. But how do you extract pure copper from its or...

Question

Explain the reactions occurring in the blast furnace during the extraction of iron.

Accepted Answer

Iron is extracted from iron oxide in a blast furnace. That is, oxide ores of iron, after concentration through calcination/roasting are mixed with limestone and coke and fed into a blast furnace from its top. In the blast furnace, reduction of iron oxides takes place in different temperature ranges. Hot air is blown from the bottom of the furnace and coke is burnt to give temperature up to about $2200 K$ in the lower portion itself. The burning of coke therefore supplies most of the heat required in the process. The $CO$ and heat moves to upper part of the furnace. In upper part, the temperature is lower and the iron oxides ( ${Fe}_{2} O_{3}$ and ${Fe}_{3} O_{4}$ ) coming from the top are reduced in steps to $FeO$ .

These reactions can be given as,

At $500 - 800 K$ (lower temperature range in the blast furnace):

$3 {Fe}_{2} O_{3} + CO \to 2 {Fe}_{3} O_{4} + {CO}_{2}$

${Fe}_{3} O_{4} + 4 CO \to 3 Fe + 4 {CO}_{2}$

${Fe}_{2} O_{3} + CO \to 2 FeO + {CO}_{2}$

At $900 - 1500 K$ (higher temperature range in the blast furnace):

$C + {CO}_{2} \to 2 CO$

$FeO + CO \to Fe + {CO}_{2}$

Limestone is also decomposed to $CaO$ which removes silicate impurity of the ore as slag. The slag is in molten state and separates out from iron.

${CaCO}_{3} \to CaO + {CO}_{2}$

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

The iron obtained from blast furnace contains about $4 %$ carbon and many impurities in smaller amount.

Explain the reactions occurring in the blast furnace during the extraction of iron.

Important Questions on General Principles of Metallurgy

Learn and Prepare for any exam you want !