Gangue is the commercially worthless material (primarily rocky or earthy impurities) that surrounds or is mixed with valuable ore minerals in raw ore deposits.
Definition and Composition: Gangue consists of:
- Unwanted minerals (silicates, carbonates, oxides)
- Rock fragments
- Soil and clay materials
- Non-metallic impurities
Common Gangue Materials:
- Silica (SiO₂)
- Limestone (CaCO₃)
- Feldspar
- Quartz
- Clay minerals
Importance in Metallurgy: Gangue must be separated from ore because:
- Contains no extractable metal
- Increases processing costs
- Reduces ore concentration
- Must be removed before smelting
Separation Process:
- Physical methods: crushing, grinding, gravity separation, magnetic separation
- Removed before chemical processing
- Waste product after ore concentration
Key Takeaways:
- Gangue = unwanted rocky impurities in ore
- Must be removed during ore processing
- Common types: silica, carbonates, silicates
- Separation improves ore quality and reduces processing costs