Patent ID: 9102998
Filing Date: 2015-08-11
Classification: C01F,C09K,C22B,H01J,Y02W

Abstract:
1. A method of recovering rare earths from a solid mixture containing at least one halophosphate and at least one compound of one or more rare earths, the method comprising the following steps: (a) carrying out acid treatment of said mixture in a liquid medium having a pH; (b) adding a base to the liquid medium so as to raise the pH of said liquid medium to a value of at least 1.5, thus obtaining a first solid phase comprising one or more rare earths at least partly as a phosphate and a first liquid phase comprising at least one alkaline-earth element of halophosphate and separating the first solid phase from the first liquid phase; (c) mixing the first solid phase with an alkaline solid compound to form a resultant mixture and calcining the resultant mixture to form a calcined product; (d) redispersing the calcined product in water to form a first resultant suspension; (e) separating a second solid phase comprising one or more rare earths at least partially as a hydroxide and a second liquid phase comprising at least one alkaline element from the first resultant suspension; (f) dispersing the second solid phase in water to form a second resultant suspension and acidifying the second resultant suspension; and (g) separating a third solid phase and a third liquid phase comprising at least one rare earth salt from the second resultant suspension.