Electrolysis of magnesium
• Dolomite and seawater is precipitated
as insoluble magnesium hydroxide
Mg(OH)2 which is subsequently treated
with HCl to give MgCl2.
• MgCl2 is fed into electrolysis cell to
produce Mg metal at cathode and Cl2
Conversion of the aluminium oxide into aluminium by electrolysis
The aluminium oxide is electrolysed in solution in molten cryolite, Na3AlF6. Cryolite is another aluminium ore, but is rare and expensive, and most is now made chemically.