Extraction of Moderately Reactive Metals

Metals in the middle of the reactivity series (e.g., iron, zinc, lead, manganese) are moderately reactive and mostly found as sulphides or carbonates. Since it is easier to extract metals from their oxides, these ores are first converted to oxides before reduction.

Conversion to Metal Oxides:

Roasting (for Sulphide Ores) → Heated in excess air

2ZnS + 3O₂ → 2ZnO + 2SO₂↑​

Calcination (for Carbonate Ores) → Heated in limited air

ZnCO₃ → ZnO + CO₂↑

Reduction to Metal: The metal oxides are reduced using carbon (coke) or more reactive metals (e.g., Na, Ca, Al).

Zinc Extraction

• From Zinc Blende (ZnS) → Roasting → ZnO
• From Calamine (ZnCO₃) → Calcination → ZnO
• Reduction using Carbon: ZnO + C → Zn + CO↑

Manganese Extraction (Thermite Reaction): Carbon cannot reduce MnO₂, so Aluminium is used.

3MnO₂ + 4Al → 3Mn + 2Al₂O₃ + heat

Iron Extraction (Thermite Reaction): Haematite (Fe₂O₃) is reduced using carbon or aluminium.

Fe₂O₃ + 3C → 2Fe + 3CO↑ Or Fe₂O₃ + 2Al → 2Fe + Al₂O₃ + heat

Thermite Welding: The thermite reaction (Fe₂O₃ + Al) releases high heat, melting iron. It is used for welding railway tracks and machine parts.

Methods used for welding rails:

Thermit Welding