Process for the recovery of rare earth elements from a solid mixture containing a halophosphate and a compound of one or more rare earth elements

摘要

Process of recovery of rare earth elements from a solid mixture comprising at least one halophosphate and at least one compound of one or more rare earth elements, characterized in that the process comprises the following steps: - (a) an acid attack of said mixture is carried out in liquid medium; - (b) a base is added to the medium obtained at the end of step (a) to raise the pH of said medium to a value of at least 1.5 whereby a first solid phase comprising one or more elements is obtained from the rare earths at least partially in the form of phosphate and a first liquid phase comprising at least one alkaline earth element of halophosphate and the first solid phase is separated from the first liquid phase; - (c) the solid resulting from step (b) is subjected to an attack with a strong base, which results in a second solid phase comprising one or more rare earth elements at least in the form of hydroxide and a second liquid phase comprising a strong base cation phosphate and the second solid phase is separated from the second liquid phase; - (d) an acid attack of the solid resulting from step (c) is carried out under conditions such that the pH of the reaction medium is less than 7, whereby a third solid phase and a third liquid phase comprising the minus a salt of rare earth elements and the third solid phase is separated from the third liquid phase.