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In the extraction of pure aluminium from sandy bauxite ore (where SiO2 is the main impurity), which of the following processes is involved?

1. Fusion with coke in presence of N2
2. Self-reduction
3. Carbon reduction
4. Electrolytic refining

Correct answer: Electrolytic refining

Solution

Sandy bauxite is purified via Bayer's process, then Al2O3 is electrolyzed (Hall-Heroult). Very pure Al is finally obtained by electrolytic refining (Hoopes process). The other options do not apply to Al.

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