Wrought iron is the purest form of iron. Write a reation 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

(a) `underset("lining")underset("Haematite")(Fe_(2)O_(3))+underset("(present in cast iron)")underset("Impurities")(3C) to underset("iron") underset("Wrought")(2Fe)+3CO`
This reaction takes place in reverberatory furnance lined with haematite.
(b) 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 oxidised and pass into slag. The metal is removed and freed from slag by passing through rollers.