The blast furnace

Iron, a metal of the greatest importance in human life, sits towards the middle of the activity series. It is therefore extracted by reduction.

The raw material

Iron is extracted from iron ore obtained from the ground. The main iron-bearing constituent of that ore is haematite (Fe₂O₃).

Figure to be added

Figure 16.1 — the blast furnace; limestone, coke and haematite fed in at the top, the waste gas outlet, the firebrick walls, the hot air blasts, and the slag and molten iron outlets.

The furnace itself

It is a special furnace about 60 m tall.

Raw materials are fed in at the top, while blasts of air heated to about 650 °C are blown in at the bottom.

The temperature inside the furnace lies in the range 1000 °C – 1900 °C.

Three raw materials

Raw material	Formula	What it does
Haematite	Fe₂O₃	the main iron-bearing constituent
Limestone	CaCO₃	removes the impurities as slag
Coke	C	produces CO, the reducing agent

They are mixed in the required proportions, finely ground and fed in at the top of the furnace. The heat introduced this way drives several reactions inside the furnace, and molten iron is obtained.