Smelting = heating ore with coke (carbon) and flux in a furnace. (1) ZnO + C → Zn + CO (~1673 K). Zinc vapour condensed. (2) SnO2 + 2C → Sn + 2CO. (3) PbO + C → Pb + CO. (4) Fe2O3 — complex blast furnace process (Note 8). Carbon works as a reducing agent for moderately electropositive metals (Zn, Fe, Sn, Pb, Cu from oxide). It CANNOT reduce Al2O3, MgO, CaO, Na2O (these metals are extracted electrolytically). The flux removes gangue: CaO (basic flux) + SiO2 (acidic gangue) → CaSiO3 (slag, fusible). SiO2 (acidic flux) + FeO (basic gangue) → FeSiO3 (slag).