Lurgi process: In the Lurgi process aluminum hydroxide is first calcined a300 to 400°C and then reacted with hydrogen fluoride in fluidized bed reactor at 400 to 600°C (dry process):



This process places high demands on the plant materials, alloys such as Inconel or Monel being used.

PCUK process: In the PCUK process calcined hydrated aluminum oxide is reacted with a mixture of hydrogen tluoride and furnace gas. The hydrogen fluoride is produced in situ from fluorspar and sulfuric acid in a directly ed rotary tube furnace. The resulting mixture of hydrogen fluoride and furnace gases is reacted with calcined aluminum hydroxide to aluminum fluoride in a fluidiLed bed reactor.

Wet process：Hydrofluoric acid (15-60% by weight) is reacted in a further process (wet process) with aluminum hydroxide to aluminum fluoride trihydrate (AlF₃^.3H₂O), which is, e.g., calcined in a rotary tube furnace.

Chemie Linz AG Process: In this process a hexafluorosilicic acid solution is reacted with aluminum hydroxide at 100°C. After separating off the silica which precipitates, the aluminum fluoride crystallizes as its trihydrate. Heating above 500°C provides anhydrous aluminum fluoride.

The dehydration of aluminum fluoride trihydrate (AlF₃^.3H₂O) above 300°C results in partial pyrolysis and the formation of aluminum oxide (Al₂O₃) and hydrogen fluoride. This is prevented by first removing 2.5 molecules of water at 200°C and then completing the drying with a short heating at 700°C.



This process is operated in Sweden, Rumania, Tunisia and Japan.

UKF Process: In the UKF process hexafluorosilicic acid is reacted with ammonia to ammonium fluoride and silica. After silica removal, the ammonium fluoride solution is reacted with double its molar quantity of aluminum oxide hydrate to a mixture of ammonium aluminum hexafluoride (ammonium cryolite) and aluminum oxide hydrate. After separation, this is converted at 500°C into aluminum fluoride, ammonia and water: