Question

The smelting of iron in a blast furnace involves the following process

• A. Combustion
• B. Reduction
• C. Slag formation
• D. Sublimation

Answer 1

Answer: (A), (B), (C)

Slag formation

In this process concentrated ore is mixed with carbon and heated, followed by addition of flux to convert the non-fusible gangue to fusible slag.

In the reduction zone, Iron (III) oxide is reduced to sponge iron by carbon monoxide. Here the temperature is 250 - 700 degree celcius.

$F{e}_2{O}_3+3CO\to 2Fe+3C{O}_2$

Further, as the feed descends down the blast furnace, limestone decomposes as

$CaC{O}_3\to CaO+C{O}_2$

(Limestone)

In the zone of slag formation, the CaO from limestone combines with siliceous impurities to form fusible slag:

$CaO$ $+Si{O}_2$ $\to$ $CaSi{O}_3$

(Slag)