Question

When the ore haematite is burnt in air with coke around `2000 K` along with lime, the process not only produces steel but also produces a silicate slag that is useful in making building materials such as cement. Discuss the same and show through balanced chemical equation.

Answer 1

Correct Answer - Heamatite `(Fe_(2)O_(3))` on burning with coke and lime at `2000K` in blast furnace results in the following.
(i) Upper zone
`(400^(@)C "to" 700^(@)C) Fe_(2)O_(3) +3CO rarr 2Fe +3CO_(2)`
`{:(3Fe_(2)O_(3)+CO rarr 2Fe_(3)O_(4)+CO_(2) ,),(Fe_(3)O_(4)+CO rarr 3FeO +CO_(2),),(underline(FeO+CO rarr Fe +CO_(2)),):}`
This reaction occurs in following steps:
(ii) Middle zone
`(800^(@)C "to" 1000^(@)C) C +CO_(2) rarr 2CO`
`FeO +CO rarr Fe(s) +CO_(2)`
(iii) Upper lower zone Impure iron metals
`(1200^(@)C "to" 1500^(@)C) CaO +SiO_(2) rarr CaSiO_(3)` (slag)
(iv) Lower zone Phosphates and silicates are reduced.
`(1500^(@)C "to" 1600^(@)C)P` and S pass into molten iron
`C + O_(2) rarr CO_(2)`