Bauxite is refined to alumina (aluminum oxide) by heating whilemixed with sodium hydroxide, where the resultant soluble compoundsodium aluminate can be removed from the ore. The aluminumhydroxide can be removed by neutralization or by seeding withAl(OH)3 crystals.This is called the Bayer process.The aluminum metal is separately removed from the alumina byelectrolysis, where alumina is dissolved in molten cryolite andaluminum ions are removed at the cathode of a very large processingcell.This is called the Hall-Heroult process.