To extract pure alumina, during the alumina recovery process, the bauxite is first crushed and finely ground, and then mixed with sodium hydroxide and heated under pressure. During this process, water-soluble sodium aluminate and insoluble sodium aluminate will be generated of iron, and wafer residues · Add freshly prepared aluminum hydroxide seed crystals to produce a pure alumina Al(OH)3) deposit · By calcining at 1200C, the water is removed, leaving pure alumina-free.

Converting alumina to aluminum (Holglauert method) Extracting aluminum from alumina requires an electrochemical method to chemically react pure alumina. Since alumina has a high melting point (2050C), cryolite is added for mixing to lower the melting point.
Electrolysis is carried out in a large or Ishiguro steel container, which contains a gauge for conducting electricity and a block that acts as an anode. During the electrolysis process, the anode reacts with the oxygen in the oxidation process, and in the side reaction generates Venusian silver and generates dioxide, 2A10. +304Al+3C02 This process can obtain aluminum with a purity of 99-99.9%. Most of them are used in aluminum alloys.