The production of rare earth fluoride is mainly through the following methods:
Hydrofluoric acid fluorination. In this method, dry hydrogen fluoride gas is reacted with rare earth oxides at 650 to 700 °C to obtain high-purity anhydrous rare earth fluoride. This process involves the use of a horizontal stationary fluorinating furnace in which the calcined rare earth oxides are packed in a platinum boat or nickel container, placed in the furnace, heated to 650°C or 700°C and kept warm for 4 to 5 hours after the furnace is sealed, then cooled to 300°C and then stopped for HF gas and continued to cool to below 100°C for discharge.
Ammonium bifluoride fluorination. This method uses solid ammonium bifluoride as a fluorinating agent under heating conditions to directly fluoride rare earth oxides into anhydrous rare earth fluoride. Rare earth fluoride and an excess of 30% NH4F· After mixing, the HF is packed in a platinum boat, heated to 300 °C in a heating furnace and kept incubated for 12 hours to make it fully react.
Wet process. This method involves adding fluoride (such as hydrofluoric acid, ammonium bifluoride, etc.) to the solution of rare earth compounds, washing and drying the resulting precipitate to prepare rare earth fluoride. The process involves the slow addition of hydrofluoric acid to a rare earth solution and an excess of 5% to 10% to allow the rare earth fluoride to precipitate completely under agitation. The resulting hydrated fluoride is filtered, washed with pure water at 70 °C and pH = 5 to 6, then dried, crushed and vacuum dehydrated at 450 to 700 °C and 1332.66x10-4Pa.