ホール・エルー法
Molten cryolite is used as a solvent for aluminium oxide (Al2O3) in the Hall–Héroult process, used in the refining of aluminium. It decreases the melting point of molten (liquid state) aluminium oxide from 2000 to 2500 °C to 900–1000 °C, thus making the extraction of aluminium more economical.