Device for recovering magnetic grains from sintered magnets or plastic magnets

Abstract

The invention concerns a method and a device for retrieving, from an object A, elements G present in a matrix M, characterized in that it comprises 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, (302), modifying the temperature T2 and/or pressure P2 values to stop the reaction transforming the intergranular phase, (303), and recovering the elements G separated front the matrix M (304).

1 . Device for recovering elements G from an object A, the object A comprising said elements G and a matrix M between the elements G, comprising at least the following elements:
 A first chamber ( 1 ) containing the object A and comprising an first introduction duct ( 5 ) for a dense fluid Fd of molar mass greater than 2 g·mol-1, a temperature setting module ( 20 ) and temperature control CT 1 , CT 2  and pressure CP 1 , CP 2 , to perform a transformation of the matrix M and a release of elements G,   A module ( 14 ,  26 ) to recover released elements G separated from the matrix M.   
     
     
         2 . Device according to  claim 1  further comprising sealing means ( 3 ,  4 ), a discharge duct ( 8 ) for a mixture containing the dense fluid Fd having served for the transformation of the matrix M and the release of elements G, wherein the discharge duct ( 8 ) is in contact with a second chamber ( 10 ) further comprising a discharge duct ( 11 ) provided with a grid or sieve ( 12 ) to prevent the passage of the released elements G and to recover the dense fluid Fd used for the reaction, a recycling circuit ( 11 ,  13 ) for the dense fluid Fd to the first chamber ( 1 ), wherein the second chamber ( 10 ) is equipped with control means that are designed to stop the transformation of the matrix M and to preserve the physicochemical properties of the released elements G. 
     
     
         3 . Device according to  claim 1  further comprising sealing means ( 3 ,  4 ), a discharge duct ( 8 ) for a mixture containing the dense fluid Fd used for the transformation of the matrix M and the release of the elements G, wherein the mixture is introduced into a cyclone-type device ( 24 ) equipped with temperature control means ( 21 ) that are designed to stop the transformation of the matrix M and to preserve the physicochemical properties of the released elements G. 
     
     
         4 . Device according to  claim 1 , wherein the chamber ( 1 ) comprises an opening ( 2 ) for the introduction of the object A to be treated. 
     
     
         5 . Device according to  claim 1 , wherein the chamber ( 1 ) comprises a cover ( 3 ) equipped with a seal ( 4 ) to ensure a tight seal. 
     
     
         6 . Device according to  claim 1 , wherein the first introduction duct ( 5 ) is equipped with a valve ( 6 ) making it possible to inject the dense fluid Fd such as a solvent stored in a reservoir ( 7 ). 
     
     
         7 . Device according to  claim 1 , wherein the chamber ( 1 ) further comprises a continuous introduction duct ( 15 ) for the object A, said object A being stored in a container ( 16 ). 
     
     
         8 . Device according to  claim 2 , wherein the mixture is discharged through the discharge duct ( 8 ) equipped with a valve ( 9 ) which opens into the second chamber ( 10 ). 
     
     
         9 . Device according to  claim 2 , wherein the recycling circuit comprises a pump ( 13 ) aiding the recycling of the dense fluid Fd in the introduction duct ( 5 ) of the main chamber ( 1 ) through the discharge duct ( 11 ). 
     
     
         10 . Device according to  claim 2 , wherein the second chamber ( 10 ) further comprises a hatch ( 14 ) located at the bottom of the second chamber ( 10 ), for evacuating the released elements G. 
     
     
         11 . Device according to  claim 3 , wherein the mixture is introduced in the cyclone-type device ( 24 ) by means of a duct ( 25 ). 
     
     
         12 . Device according to  claim 3 , wherein the cyclone-type device ( 24 ) is composed of a body and a conical section. 
     
     
         13 . Device according to  claim 3 , wherein the temperature control means ( 21 ) of the cyclone-type device ( 24 ) are cooling means ( 21 ). 
     
     
         14 . Device according to  claim 3 , wherein the cyclone-type device ( 24 ) further comprises temperature and pressure sensors CT 2 , CP 2 . 
     
     
         15 . Device according to  claim 3 , wherein the cyclone-type device ( 24 ) further comprises a discharge duct ( 26 ) for recovering the released elements G separated from the dense fluid Fd, and a duct ( 27 ) comprising a pump ( 13 ) aiding the recycling of the dense fluid Fd in the introduction duct ( 5 ) of the main chamber ( 1 ). 
     
     
         16 . Device according to  claim 1 , wherein the temperature setting module ( 20 ) of the first chamber ( 1 ) is a heating means, for examples a heating resistor. 
     
     
         17 . Device according to  claim 2 , wherein the first chamber ( 1 ) is equipped with a temperature sensor CT 1  and a pressure sensor CP 1  to monitor the temperature and the pressure in the first chamber ( 1 ) in which the transformation of the matrix M takes place, and the second chamber ( 10 ) is equipped with temperature sensor CT 2  and pressure sensor CP 2  and cooling means ( 12 ) to stop the transformation. 
     
     
         18 . Device according to  claim 17 , wherein the temperature sensor CT 1  in the first chamber ( 1 ) controls the temperature between 100° C. and 400° C., and the temperature sensor CT 2  of the second chamber ( 10 ) controls the temperature to be below 100° C. and higher than the solidification temperature of the dense fluid Fd, and the pressure sensor CP 2  of the second chamber ( 10 ) controls the pressure to be lower than 25 MPa and greater than 0.1 MPa. 
     
     
         19 . Device according to  claim 1 , wherein the object A is a sintered magnet, the elements G are magnetic grains and the matrix M is an intergranular phase between the magnetic grains of the sintered magnet. 
     
     
         20 . Device according to  claim 1 , wherein the object A is a Nd—Fe—B magnet, the elements G are Nd2Fe14B grains and the matrix M is the intergranular phase of the Nd—Fe—B magnet.