Extractive metallurgy is the practice of separating out metals from ore during mineral processing. Metals naturally occur usually as oxide or sulfide minerals (e.g., CuO or CuS, where Cu has a positive valence charge such as +2 or +1), which must be first separated from the gangue minerals (e.g., SiO2). Once the metal-bearing minerals are concentrated together, they must be reduced to produce the actual metal (e.g., Cu metal, where Cu has a 0 valence).

Common separation and reduction methods include:

• Hydrometallurgy:
  • Leaching - chemical agent dissolves metal-minerals from the ore
  • Electrowinning - dissolved metal-bearing minerals are reduced to form metal
• Pyrometallurgy:
  • Comminution and concentration - metal-bearing minerals are liberated from the gangue by crushing and grinding, and then concentrated together using froth flotation or other means
  • Smelting - the concentrated metal-bearing minerals are heated with a reducing agent to form metal