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

摘要

The present invention relates to a process for the selective recovery of rare earths from an aqueous acid sulphate solution comprising phosphates, aluminum and heavy rare earths, and optionally medium rare earths, iron II and titanium, characterized in what it comprises the following successive stages: a) neutralization at a pH of between 3 and 4 of an aqueous acid solution of sulphate comprising phosphates, aluminum and heavy rare earths, and optionally medium rare earths, iron II and titanium, the solution having an Al / P molar ratio 1 and a sulphate concentration 100 g / L by adding a base, so as to precipitate the phosphate and the aluminum and any titanium , b) liquid / solid separation between the precipitate formed by the phosphate and the aluminum and the possible titanium and the aqueous sulphate solution, c) recovery of the aqueous sulphate solution, d) addition of phosphates to the aqueous solution e of sulfate obtained in step c) such as the molar ratio of the solution obtained PO4 / TR 4, so as to precipitate the heavy rare earth phosphates and any medium rare earth phosphates, e) liquid / solid separation between the precipitate formed by the heavy rare earth phosphates and any medium rare earth phosphates and the aqueous sulfate solution, f) recovery of the precipitate formed by the heavy rare earth phosphates and any medium rare earth phosphates.