Precipitation
The purified rare earth liquid from the SX plant is treated with a reagent (like oxalic acid or ammonium bicarbonate). This causes the rare earth to fall out of the solution as a solid crystal (a precipitate).
Calcination
This solid is filtered and then passed through a furnace (calciner) at high temperatures. The heat burns off the carbon and oxygen, leaving behind a pure **Rare Earth Oxide (REO)**. This powder is the standard form in which rare earths are traded globally.