In the process of aluminum smelting, cryolite is used as the main raw material for aluminum smelting because:

1. Pure cryolite does not contain any metal impurities with precipitation potential higher than aluminum. Relatively pure aluminum can be obtained as long as no impurities are added from the outside during operation.

2. Cryolite can dissolve alumina well. When the electrolysis temperature is 950 ℃ - 970 ℃, the solubility of alumina in cryolite solution is about 10%.

3. At the electrolysis temperature, the density of cryolite alumina solution is lower than that of molten aluminum at the same temperature. It can float on the molten aluminum to prevent aluminum oxidation, and the electrolyte and aluminum can be better separated.

4. Cryolite has certain conductivity, so the voltage drop of electrolyte layer will not be too high.

5. Cryolite melt has certain fluidity at electrolytic temperature, and anode gas can be discharged from electrolyte, which is conducive to the cyclization of electrolyte.

6. In the molten state, cryolite basically does not absorb water and volatilize, which reduces material consumption and ensures the stability of electrolyte.

Cryolite, also known as sodium hexafluoroaluminate or sodium aluminum fluoride, with molecular formula of Na3AlF6, is a small white crystal, tasteless and more soluble than natural cryolite. Cryolite is mainly used as aluminum electrolytic flux, rubber and grinding wheel wear-resistant filler, enamel paste, glass sunscreen and metal flux, crop insecticide. Under normal circumstances, it does not decompose, volatilize or deliquescence. Its melting point is higher than aluminum, its conductivity is good, and it saves energy. It can be said that without cryolite, there may not be such a large-scale aluminum industry in the world.