Magnet Recycling

Abstract

Methods, systems, and apparatus, including computer programs encoded on computer storage media, for recycling magnetic material to restore or improve the magnetic performance One of the methods includes fragmenting magnetic material to form a powder, mixing the powder with a) a rare earth material R and b) an elemental additive A to produce a homogeneous powder, wherein the rare earth material comprises at least one of: i) Nd, ii) Pr, and iii) Dy, and the elemental additive A comprises at least one of: i) Co, ii) Cu, and iii) Fe, and sintering and magnetizing the homogenous powder to form a Nd—Fe—B magnetic product.

What is claimed is:  
     
         1 . A method for manufacturing an Nd—Fe—B permanent magnet comprising:
 fragmenting magnetic material to form a powder; 
 removing particles with a particle fraction size bigger than an average size of particles in the magnetic material from the magnetic material to obtain 1.98 at. % oxygen or less in the magnetic material; 
 mixing the powder with a) a rare earth material R and b) an elemental additive A to produce a homogeneous powder, wherein the rare earth material R comprises at least one of: i) Nd, ii) Pr, and iii) Dy, and the elemental additive A comprises at least one of: i) Co, ii) Cu, and iii) Fe; and 
 sintering and magnetizing the homogenous powder to form a Nd—Fe—B magnetic product. 
 
     
     
         2 . The method of  claim 1  wherein removing, from the magnetic material, particles with the particle fraction size bigger than the average size of particles in the magnetic material to obtain 1.98 at. % oxygen or less in the magnetic material comprises sieving. 
     
     
         3 . The method of  claim 1  wherein removing, from the magnetic material, particles with the particle fraction size bigger than the average size of particles in the magnetic material to obtain 1.98 at. % oxygen or less in the magnetic material comprises removing particles in an inert atmosphere. 
     
     
         4 . The method of  claim 3  wherein removing particles in an inert atmosphere comprises removing particles in argon. 
     
     
         5 . The method of  claim 1  comprising:
 mixing the homogenous powder with another element selected from the elemental additive A. 
 
     
     
         6 . The method of  claim 1  wherein:
 mixing the powder with a) the rare earth material R and b) the elemental additive A to produce the homogeneous powder comprises homogeneously distributing the rare earth material R and the elemental additive A within the magnetic material; and 
 sintering and magnetizing the homogenous powder to form the Nd—Fe—B magnetic product comprises forming the Nd—Fe—B magnetic product with a concentration of the rare earth material R and a concentration of the elemental additive A that increases, on average, surrounding a primary Nd 2 Fe 14 B phase within the Nd—Fe—B magnetic product. 
 
     
     
         7 . The method of  claim 6  wherein forming the Nd—Fe—B magnetic product comprises modifying an elemental concentration and an elemental composition of a grain boundary phase, on average, at a plurality of grain boundary regions that extend throughout the Nd—Fe—B magnetic product by:
 forming NdPrH 3  from H 2  processing gas and the rare earth material R; and 
 during sintering, transforming the NdPrH 3  to oxygen free NdPr. 
 
     
     
         8 . The method of  claim 1 , wherein mixing the powder with a) the rare earth material R and b) the elemental additive A to produce a homogeneous powder, wherein the rare earth material R comprises at least one of: i) Nd, ii) Pr, and iii) Dy, and the elemental additive A comprises at least one of: i) Co, ii) Cu, and iii) Fe comprising mixing the powder with a) the rare earth material R that comprises between 0.1 to 1 at. % of the total mixture and b) the elemental additive A to produce the homogeneous powder. 
     
     
         9 . The method of  claim 1 , wherein mixing the powder with a) the rare earth material R and b) the elemental additive A to produce the homogeneous powder, wherein the rare earth material R comprises at least one of: i) Nd, ii) Pr, and iii) Dy, and the elemental additive A comprises at least one of: i) Co, ii) Cu, and iii) Fe comprising mixing the powder with a) a rare earth material R and b) an elemental additive A to produce the homogeneous powder, wherein the rare earth material R comprises Nd and Pr with a ratio of 25 wt. % Nd to 75 wt. % Pr. 
     
     
         10 . The method of  claim 1 , wherein mixing the powder with a) the rare earth material R and b) the elemental additive A to produce the homogeneous powder, wherein the rare earth material R comprises at least one of: i) Nd, ii) Pr, and iii) Dy, and the elemental additive A comprises at least one of: i) Co, ii) Cu, and iii) Fe comprising mixing the powder with a) a rare earth material R and b) an elemental additive A to produce the homogeneous powder, wherein the rare earth material R comprises Nd and Pr with a ratio of 75 wt. % Nd to 25 wt. % Pr. 
     
     
         11 . The method of  claim 1  comprising performing the fragmenting, removing, and the mixing concurrently. 
     
     
         12 . The method of  claim 1  wherein fragmenting the magnetic material comprises fragmenting the magnetic material to an average particle size between 1 to 4 microns. 
     
     
         13 . The method of  claim 1  wherein fragmenting the magnetic material to form the powder comprises fragmenting the magnetic material to form the powder with an average particle size between about 1 micron to about 2 millimeters, the method comprising:
 further fragmenting the powder to an average particle size between about 1 to about 4 microns; and 
 homogenizing the powder. 
 
     
     
         14 . The method of  claim 13  wherein:
 homogenizing the powder comprises homogenizing the powder that comprises an average particle size between about 1 micro to about 2 millimeters; and 
 mixing the powder with a) the rare earth material R and b) the elemental additive A to produce the homogeneous powder comprises mixing the powder with an average particle size between about 1 to about 4 micros with a) the rare earth material R and b) the elemental additive A to produce the homogenous powder. 
 
     
     
         15 . The method of  claim 13  wherein:
 mixing the powder with a) the rare earth material R and b) the elemental additive A to produce the homogeneous powder comprises mixing the powder with an average particle size between about 1 micron to about 2 millimeters with a) the rare earth material R and b) the elemental additive A to produce the homogenous powder; and 
 homogenizing the powder comprises homogenizing the powder that comprises an average particle size between about 1 to about 4 microns. 
 
     
     
         16 . The method of  claim 1  comprising:
 fragmenting the rare earth material R and the elemental additive A separately from fragmenting the magnetic material to form the powder, wherein mixing the powder with a) the rare earth material R and b) the elemental additive A to produce the homogeneous powder comprises mixing the powder with a) the fragmented rare earth material R and b) the fragmented elemental additive A to produce the homogeneous powder. 
 
     
     
         17 . The method of  claim 1  where sintering and magnetizing the homogenous powder to form a recycled Nd—Fe—B magnetic product comprises:
 adding a lubricant to the homogenous powder; 
 compacting the homogenous powder to form a green compact; 
 sintering the green compact between about 1000° C. to about 1100° C.; 
 heat treating the sintered green compact between about 490° C. to about 950° C.; and 
 magnetizing the heat treated green compact to an inert atmosphere below 15° C. to form the recycled Nd—Fe—B magnetic product. 
 
     
     
         18 . The method of  claim 1  wherein sintering and magnetizing the homogenous powder to form the Nd—Fe—B magnetic product that comprises 1.98 at. % oxygen or less comprises sintering and magnetizing the homogenous powder to form the Nd—Fe—B magnetic product that comprises between 1.32 to 1.98 at. % oxygen. 
     
     
         19 . The method of  claim 1 , wherein sintering and magnetizing the homogenous powder to form the Nd—Fe—B magnetic product that comprises 1.98 at. % oxygen or less comprises sintering and magnetizing the homogenous powder to form the Nd—Fe—B magnetic product that has a remanence and a coercivity at least the same as the magnetic material. 
     
     
         20 . The method of  claim 19 , wherein the coercivity of the Nd—Fe—B magnetic product is between about 0 to about 20% greater than the coercivity of the magnetic material. 
     
     
         21 . The method of  claim 1  comprising:
 sintering and magnetizing the homogenous powder to form the Nd—Fe—B magnetic product with a final remanence and a final coercivity, wherein the final remanence is about  97 % of another remanence of the magnetic material and the final coercivity is at least  30 % greater than another coercivity of the magnetic material. 
 
     
     
         22 . The method of  claim 1  comprising:
 sintering and magnetizing the homogenous powder to form the Nd—Fe—B magnetic product with a final remanence and a final coercivity, wherein the final remanence is about 95% of another remanence of the magnetic material and the final coercivity is at least 80% greater than another coercivity of the magnetic material. 
 
     
     
         23 . The method of  claim 1  comprising:
 sintering and magnetizing the homogenous powder to form the Nd—Fe—B magnetic product with a final remanence and a final coercivity, wherein the final remanence is about  5 % greater than another remanence of the magnetic material and the final coercivity is at least the same as another coercivity of the magnetic material. 
 
     
     
         24 . The method of  claim 1  wherein an atomic percentage of Co in the Nd—Fe—B magnetic product is less than or equal to 3 at. %. 
     
     
         25 . The method of  claim 1  wherein an atomic percentage of Cu in the Nd—Fe—B magnetic product is less than or equal to 0.3 at. %. 
     
     
         26 . The method of  claim 1  wherein a combined atomic percentage of Fe and Co in the Nd—Fe—B magnetic product is less than or equal to 77 at. %. 
     
     
         27 . The method of  claim 1  wherein a combined atomic percentage of Nd, Dy, and Pr in the Nd—Fe—B magnetic product is less than or equal to 18 at. %. 
     
     
         28 . The method of  claim 1  wherein:
 sintering and magnetizing the homogenous powder to form the Nd—Fe—B magnetic product comprises sintering and magnetizing the homogenous powder to form the Nd—Fe—B magnetic product having a composition substantially of W a R b A c , where W comprises Nd—Fe—B material from the magnetic material; 
 indices a, b, and c comprise atomic percentages of the corresponding compositions or elements; 
 a(t) is the atomic percent of element t in the magnetic material W relative to the composition of the Nd—Fe—B magnetic product; 
 b(t) is the atomic percent of element t in the rare earth containing material R relative to the composition of the Nd—Fe—B magnetic product; 
 c(t) is the atomic percent of element t in the elemental additives A relative to the composition of the Nd—Fe—B magnetic product; and 
 a, b, c, a(t), b(t), and c(t) have values satisfying:
 81 at. %≦a≦99.9 at. %, 
 0.1 at. %≦b≦1 at. %, 
 3 at. %—99.9% * a(Co)≦c(Co)≦3 at. %—81% *a(Co), 
 0.3 at. %—99.9% * a(Cu)≦c(Cu)≦0.3 at. %—81% *a(Cu), 
 77 at. %—99.9% *(a(Fe)+a(Co))≦c(Fe)≦77 at. %—81%*(a(Fe)+a(Co)), 
 a(Nd)+b(Nd)+a(Pr)+b(Pr)>0 at. %, 
 a(Nd)+b(Nd)+a(Pr)+b(Pr)+a(Dy)+b(Dy)+c(Dy)≦18 at. %, 
 a(Co)+b(Co)+c(Co)≦3 at. %, 
 a(Cu)+b(Cu)+c(Cu)≦0.3 at. %, 
 a(Fe)+b(Fe)+c(Fe)+a(Co)+b(Co) +c(Co) <77 at. %, and 
 b(Nd)+b(Pr)+b(Dy)+c(Dy)≧0 at. %. 
 
 
     
     
         29 . The method of  claim 1  wherein sintering and magnetizing the homogenous powder to form the Nd—Fe—B magnetic product comprises sintering and magnetizing the homogenous powder to form the Nd—Fe—B magnetic product having a composition substantially of W a R b A c , where W comprises Nd—Fe—B material from the magnetic material and indices a, b, and c comprise atomic percentages of the corresponding compositions or elements and the rare earth material R and the elemental additive A satisfy:
 Nd[0.1-19%*s(Nd), x], 
 Pr[0.1-19%*s(Pr), y], 
 Dy[0.1-19%*s(Dy), z], 
 Co[0 at. %, d], 
 Cu[0 at. %, e], 
 Fe[0 at. %, f], 
 wherein:
 [m, n] means a range from a first value in a minimum interval m and a second value in a maximum interval n; 
 s(t) is the atomic percent of element t in starting composition; 
 x=18 at. %—[81, 99.9]% * (s(Nd)+s(Pr)+s(Dy)), wherein (s(Nd)+s(Pr)+s(Dy))≦18.01801802 at. %; 
 y=18 at. %—[81, 99.9] % * (s(Nd)+s(Pr)+s(Dy)); 
 z=18 at. %—[81, 99.9] % * (s(Nd)+s(Pr)+s(Dy)); 
 d=3 at. %—[81, 99.9] % * s(Co), wherein s(Co)≦3.003003003 at. %; 
 e=0.3 at. %—[81, 99.9] % * s(Cu), wherein s(Cu)≦0.3003003 at. %; and 
 f=77 at. %—[81, 99.9] % * (s(Fe)+s(Co)), wherein (s(Fe)+s(Co))≦77.07707708 at. %. 
 
 
     
     
         30 . The method of  claim 1  comprising:
 harvesting the magnetic material from one or more magnet assemblies by:
 separating a waste magnet part from a non-magnet part included in the magnet assemblies; and 
 extracting the waste magnet part from the non-magnet part, wherein the magnetic material comprises the waste magnet part. 
 
 
     
     
         31 . The method of  claim 1  comprising:
 demagnetizing magnetic material from a waste magnet assembly by cyclic heating and cooling of the magnetic material, fragmenting adhesives attached to the magnetic material, cracking coating layers of the magnetic material, and subjecting the magnetic material to at least one of: a) a mechanical treatment or b) a chemical treatment, to remove the coating layers and prepare the magnetic material. 
 
     
     
         32 . The method of  claim 31  wherein demagnetizing the magnetic material from the waste magnet assembly by cyclic heating and cooling of the magnetic material comprises demagnetizing a waste magnet part, that comprises the magnetic material, from the waste magnet assembly to fragment the adhesives that bond the waste magnet part to a non-magnet part and to crack at least one coating layer selected from: an electrolytic black Epoxy, a Ni, a Ni—Cu, a Ni—Ni, a Ni—Cu—Ni, or a Zn coating layer of the waste magnet part. 
     
     
         33 . The method of  claim 31  wherein the cyclic heating and cooling comprises:
 heating the magnetic material to a Curie temperature of the rare earth material R; and 
 cooling, after heating to the Curie temperature of the rare earth material R, the magnetic material at a rate of at least 100° C./sec. 
 
     
     
         34 . The method of  claim 31  wherein a combined atomic percentage of Nd, Pr, and Dy in the Nd—Fe—B magnetic product is greater than or equal to a combined atomic percentage of Nd, Pr, and Dy in a waste magnet part from the waste magnet assembly.