METHOD FOR SELECTIVELY RECOVERING THE RARE EARTHS FROM AN AQUEOUS ACID SULFATE SOLUTION RICH IN ALUMINUM AND PHOSPHATES

摘要

The present invention relates to a process for the selective recovery of the rare earth metals from an acidic aqueous sulfate solution comprising phosphates, aluminum and heavy rare earth metals, and possibly medium rare earth metals, iron(II) and titanium, characterized in that it comprises the following successive stages: a) neutralization at a pH of between 3 and 4 of an acidic aqueous sulfate solution comprising phosphates, aluminum and heavy rare earth metals, and possibly medium rare earth metals, iron(II) and titanium, the solution having a molar ratio Al/P>1 and a concentration of sulfates>100 g/l, by addition of a base, so as to precipitate the phosphate and the aluminum and the possible titanium, b) liquid/solid separation between the precipitate formed by the phosphate and the aluminum and the possible titanium and the aqueous sulfate solution, c) recovery of the aqueous sulfate solution, d) addition of phosphates to the aqueous sulfate solution obtained in stage c) such that the molar ratio of the solution obtained PO4/REs>4, so as to precipitate the heavy rare earth metal phosphates and the possible medium rare earth metal phosphates, e) liquid/solid separation between the precipitate formed by the heavy rare earth metal phosphates and the possible medium rare earth metal phosphates and the aqueous sulfate solution, f) recovery of the precipitate formed by the heavy rare earth metal phosphates and the possible medium rare earth metal phosphates.

主权项

1. A process for the selective recovery of the rare earth metals from an acidic aqueous sulfate solution comprising phosphates, aluminum and heavy rare earth metals, and possibly medium rare earth metals, iron(II) and titanium, wherein it comprises the following successive stages:
a) neutralization at a pH of between 3 and 4 of an acidic aqueous sulfate solution comprising phosphates, aluminum and heavy rare earth metals, and possibly medium rare earth metals, iron(II) and titanium, the solution having a molar ratio Al/P>1 and a concentration of sulfates>100 g/l, by addition of a base, so as to precipitate the phosphate and the aluminum and the possible titanium, b) liquid/solid separation between the precipitate formed by the phosphate and the aluminum and the possible titanium and the aqueous sulfate solution, c) recovery of the aqueous sulfate solution, d) addition of phosphates to the aqueous sulfate solution obtained in stage c) such that the molar ratio of the solution obtained PO4/REs>4, so as to precipitate the heavy rare earth metal phosphates and the possible medium rare earth metal phosphates, e) liquid/solid separation between the precipitate formed by the heavy rare earth metal phosphates and the possible medium rare earth metal phosphates and the aqueous sulfate solution, f) recovery of the precipitate formed by the heavy rare earth metal phosphates and the possible medium rare earth metal phosphates.