Electrochemical extraction (electrolysis of molten NaCl, Al₂O₃) (Al₂O₃ dissolved in cryolite electrolyzed with carbon anodes → 2Al(l) at cathode + CO/CO₂)
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Al₂O₃ dissolved in cryolite electrolyzed with carbon anodes → 2Al(l) at cathode + CO/CO₂ at anode
What each symbol means
| Symbol | What it stands for |
|---|---|
| CaF₂ | Fluorspar — added to further lower melting point and increase fluidity |
| Al₂O₃ | Alumina (purified by Bayer's process from bauxite ore) |
| C (anode) | Carbon anodes — consumed during electrolysis, producing CO₂ |
| Na₃AlF₆ | Cryolite — lowers melting point from 2345 K to ~1250 K |
When to use this
Used for highly electropositive metals (Na, K, Mg, Ca, Al) that cannot be reduced by carbon or CO. Cryolite lowers melting point of Al₂O₃ and increases conductivity. Downs cell uses molten NaCl + CaCl₂ for Na extraction.