The Iron Blast Furnace

Iron is extracted from an ore that contains iron (III) oxide called haematite.

Coke is impure carbon. It burns to form carbon dioxide. This is a strongly exothermic reaction.

C + O₂ -> CO₂

At high temperatures, the carbon dioxide is reduced by more carbon to give carbon monoxide.

C + CO₂ -> 2CO

Carbon monoxide is the main reducing agent:

Fe₂O₃ + 3CO -> 2Fe + 3CO₂

Carbon may also reduce the iron (III) oxide:

Fe₂O₃ + 3C -> 2Fe + 3CO

The heat of the furnace causes the limestone to thermally decompose to form calcium oxide and carbon dioxide:

CaCO₃ -> CaO + CO₂

The calcium oxide reacts with silicon dioxide (one of the impurities found in haematite) to form calcium silicate, which melts and trickles to the bottom of the furnace as molten slag:

SiO₂ + CaO -> CaSiO₃

Uses of Iron (you don’t really need to learn this)
Types of Iron	Iron Mixed With	Some Uses
Wrought Iron	Pure Iron	Decorative work such as gates and railings
Mild Steel	0.25% Carbon	Nails, car bodies, ship building
High – Carbon Steel	0.25 – 1.5% Carbon	Cutting tools
Cast Iron	About 4% Carbon	Manhole covers, guttering, engine blocks
Stainless Steel	Chromium and Nickel	Cutlery, cooking utensils

Preventing the Rusting of Iron (in which iron oxidises into iron oxide Fe₂O₃)
Using Barriers	Keep water/oxygen away from the iron by painting, coating with oil…etc.
Alloying the Iron	Such as allowing it with chromium and nickel to produce stainless steel
Using Sacrificial Anodes	Galvanising iron by coating it with a layer of zinc. Zinc is more reactive than iron and will corrode instead. During the process it loses electrons to form ions. These electrons flow into the iron so any iron atom which has lost electrons immediately regains them. These means even if the zinc is scratched, the iron won’t rust.