Abstract: Disclosed is a method and a device for retrieving, from an object A, elements G present in a matrix M, the method including at least the following steps: bringing said abject A into contact with a dense fluid Fd with a molar mass greater than 2 g mol?1 under temperature T1 and pressure P1 conditions suitable for transforming the intergranular phase and for releasing the elements G, modifying the temperature T2 and/or pressure P2 values to stop the reaction transforming the intergranular phase, and recovering the elements G separated front the matrix M.

Abstract: Disclosed is a method and system for recovering at least rare earth elements from within an object A consisting of at least one first rare earth portion or a mixture of rare earth elements and a second metal portion. The method includes a solvothermal treatment step that places the object in contact with a fluid for causing at least one rare earth portion and/or mixture of rare earth elements and the metal portion to oxidize in order to separate same, the value of the reaction temperature Tr is selected according to the nature of the object, the reaction following a R-M?R(X)x+M(X)y scheme, where R is the rare earth element or a mixture of rare earth elements, M is the transition metal, and (X) is a group which depends on the fluid used.

Abstract: Disclosed is a method and a device for retrieving, from an object A, elements G present in a matrix M, the method including at least the following steps: bringing said abject A into contact with a dense fluid Fd with a molar mass greater than 2 g mol?1 under temperature T1 and pressure P1 conditions suitable for transforming the intergranular phase and for releasing the elements G,, modifying the temperature T2 and/or pressure P2 values to stop the reaction transforming the intergranular phase,, and recovering the elements G separated front the matrix M.