Explain the extraction of iron from haematite, with a labelled diagram of the blast furnace.

1. 1 · Name the ore. Iron is extracted from haematite, Fe₂O₃.
2. 2 · Concentration. Gravity separation: a stream of water washes away the lighter gangue.
3. 3 · Roasting and calcination. The ore is heated in air in a reverberatory furnace to remove moisture, sulphur and arsenic.
4. 4 · Smelting in the blast furnace.
   • Charge: roasted ore, coke and limestone (8 : 4 : 1); hot air is blown in from below.
   • Combustion zone, 1500 °C: C + O₂ → CO₂
   • Fusion zone, 1000 °C: CO₂ + C → 2CO; CaCO₃ → CaO + CO₂; CaO + SiO₂ → CaSiO₃
   • Reduction zone, 400 °C: Fe₂O₃ + 3CO → 2Fe + 3CO₂
5. 5 · Draw the blast furnace. [Tower with charge inlet at the top, waste gas outlet, three zones with temperatures, hot air inlets, slag and molten iron outlets, all labelled]
6. 6 · Collect the products. Molten iron sinks to the bottom and slag floats on it. Both are tapped off. The iron is called pig iron.
7. 7 · Real-life link. Pig iron is made into steel for buses, bridges and the almirahs in our homes.
8. 8 · Close in one line. Thus carbon monoxide made from coke reduces haematite to iron in the blast furnace.

Scoring tip: Write every zone with its temperature and balanced equation. The labelled blast furnace carries a big share of the marks.