Gangue is the unwanted rocky impurities in ore; flux is a substance added to remove gangue by forming slag; and slag is the waste product formed when flux combines with gangue during smelting.
1. Gangue:
- Definition: Worthless earthy/rocky impurities naturally present in ores
- Examples: Silica (SiO₂), clay, limestone in metal ores
- Problem: Cannot be melted or extracted easily with metal
2. Flux:
- Definition: Substance intentionally added during smelting to remove gangue
- Function: Reacts with gangue to form easily removable slag
- Types:
- Acidic flux: Silica (SiO₂) - removes basic gangue
- Basic flux: Limestone (CaCO₃), lime (CaO) - removes acidic gangue
- Selection rule: Flux is opposite nature to gangue
3. Slag:
- Definition: Fusible waste product formed from flux + gangue reaction
- Properties: Lower melting point than metal, lighter density
- Removal: Floats on molten metal, easily skimmed off
- Uses: Road construction, cement manufacture
Chemical Example: CaCO₃ (flux) + SiO₂ (gangue) → CaSiO₃ (slag) + CO₂
Key Takeaways:
- Gangue: natural impurity in ore
- Flux: added chemical to remove gangue
- Slag: flux + gangue reaction product
- Process enables pure metal extraction