Hall-Héroult process The Hall-Héroult process is the major industrial process for the production of aluminium. It involves dissolving alumina in molten cryolite, and electrolysing the solution to obtain pure aluminium metal. Alumina Al2O3 Cryolite Na3AlF6 Aluminum fluoride AlF3 110kV 340kA Aluminum Al liquid Hydrogen fluoride HF gas Carbon dioxide CO2 gas