Method for recovering rare-earth elements from a solid mixture containing a halophosphate and a compound of one or more rare-earth elements
AssigneeRhodia Operations
InventorsJean-Jacques Braconnier, Alain Rollat
Life of this patent
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Abstract
A method is described for recovering rare earth elements from a solid mixture including a halophosphate and at least one compound of one or more rare earth elements. The method includes: (a) acid etching the mixture; (b) adding a base to bring the pH back up to a value of at least 1.5; (c) etching the solid from step (b) with a solution of soda or potash; (d) acid etching the solid from step (c) until a pH of less than 7 is obtained, resulting in a solid phase and a liquid phase including at least one rare earth salt, and separating the solid phase from the liquid phase.
Claims11
A method of recovering rare-earth elements from a solid mixture comprising at least one halophosphate and at least one compound of one or more rare-earth elements, wherein the method comprises the following steps:
- (a) carrying out acid attack on said mixture in a liquid medium;
- (b) adding a base to the medium obtained at the end of step (a) so as to raise the pH of said medium to a value of at least 1.5, whereby a first solid phase is obtained comprising one or more rare-earth elements at least partly in the form of phosphate and a first liquid phase comprising at least one alkaline-earth element of halophosphate and separating a first solid phase from the first liquid phase;
- (c) attacking the first solid phase resulting from step (b) with a strong base, whereby a second solid phase is obtained comprising one or more rare-earth elements at least in the form of hydroxide and a second liquid phase comprising a phosphate of a cation of the strong base and separating the second solid phase from a second liquid phase;
- (d) carrying out acid attack on the second solid phase resulting from step (c) in conditions such that the pH of the reaction mixture is below 7, whereby a third solid phase is obtained and a third liquid phase comprising at least one rare-earth salt and separating the third solid phase from the third liquid phase.
Dependencies are inferred from the claim text.