Wrought iron is the purest form of iron. Write a reaction used for the preparation of wrought iron from cast iron. How can the impurities of sulphur, silicon and phosphorus be removed from cast iron?

Explanation

(i) `underset("Haematite lining")(Fe_(2)O_(3)) + underset(("present in cast iron"))underset("Impurities")(3C) rarr underset("Wrought iron")(2Fe) + 3CO`
This reaction takes place in reverberatory furnace lined with haematite.
(ii) The haematite oxidises S to `SO_(2)`, Si to `SiO_(2)` and P to `P_(4)O_(10)`. Sometimes limestone is added as flux. Impurities of S, Si and P oxidise and pass into slag. The metal is removed and freed from slag by passing through rollers.