Chemical dismantling of permanent magnet material and battery material

Abstract

Certain method embodiments are described and useful for recycling permanent magnet materials (e.g. permanent magnet alloys) and battery materials (e.g. battery electrode materials) to extract critical and/or valuable elements including REEs, Co and Ni. Method embodiments involve reacting such material with at least one of an ammonium salt and an iron (III) salt to achieve at least one of a liquid phase chemical reaction and a mechanochemical reaction.

Claims

1. A method for use in recycling of a material that includes a metal content to be recovered comprising at least one of a rare earth metal, cobalt, and nickel, wherein the rare earth metal includes at least one of Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, comprising the step of contacting the material and a chemical reagent that includes at least one of an ammonium salt and iron (lll) salt without added oxygen reagent at a temperature up to about 100° C. to carry out at least one of a liquid phase chemical reaction and a mechanochemical reaction with the metal content to form a non-oxide and water soluble derivative of the at least one rare earth metal, cobalt and nickel.

2. The method of claim 1 wherein the contacting is carried out at a temperature from room temperature to about 100° C.

3. The method of claim 1 where the contacting is carried out by mechanical milling of the material in the presence of at least one of the ammonium salt and iron (lll) salt in the absence of water or another solvent to achieve a mechanochemical solid state reaction.

4. The method of claim 1 where the contacting is carried out by mechanical milling of the material in the presence of water and of at least one of the ammonium salt and iron (lll) salt at room temperature.

5. The method of claim 1 where the contacting is carried out in an aqueous environment or in a solution containing water as one component.

6. The method of claim 5 where the contacting is carried out in a first step by means of the mechanochemical reaction and then in a second step by means of the liquid phase chemical reaction in aqueous environment at a temperature from room temperature to about 100° C.

7. The method of claim 1 wherein the material comprises at least one of a permanent magnet alloy and a battery alloy containing at least one of the rare earth metal, cobalt and nickel.

8. The method of claim 1 that produces a water-soluble derivative of Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ni or Co.

9. The method of claim 8 comprising precipitating the water soluble derivative of at least one rare earth metal in the form of a rare earth metal compound.

10. The method of claim 8 comprising precipitating the water soluble derivative of least one of cobalt and nickel in the form of at least one of a cobalt compound and nickel compound.

11. The method of claim 9 including the further step of calcining the rare earth metal compound to produce a rare earth metal oxide.

12. The method of claim 1, wherein the ammonium salt contains at least one anion comprising a Cl.sup.−, Br.sup.−, I.sup.−, NO.sub.3.sup.−, HSO.sub.4.sup.−, and SO.sub.4.sup.2−.

13. The method of claim 1, wherein the iron (lll) salt contains at least one anion comprising a Cl.sup.−, Br.sup.−, I.sup.−, NO.sub.3.sup.−, HSO.sub.4.sup.−, and SO.sub.4.sup.2.

14. The method of claim 1, wherein the contacting includes contacting the ammonium salt and a samarium-cobalt permanent magnet or magnetic alloy.

15. The method of claim 1, wherein the contacting includes contacting the ammonium salt and a rare earth-iron-boron permanent magnet or magnetic alloy.

16. The method of claim 1, wherein the contacting includes contacting the ammonium salt and a rare earth-containing magnet material or alloy and/or nickel-based battery material or alloy.

17. The method of claim 1, wherein the contacting includes contacting the iron (lll) salt and a samarium-cobalt permanent magnet or magnetic alloy.

18. The method of claim 1, wherein the contacting includes contacting the iron (lll) salt and a rare earth-iron-boron permanent magnet or magnetic alloy.

19. The method of claim 1, wherein the contacting includes contacting the iron (lll) salt and a rare earth-containing magnet material and/or a nickel-based battery material or alloy.

20. The method of claim 1, wherein the chemical reaction or mechanochemical reaction is carried out in an aqueous environment.

21. The method of claim 20, wherein the aqueous environment is maintained at a temperature between 0° C. and about 100° C.

22. The method of claim 1 wherein the mechanochemical reaction is conducted by at least one of mechanical milling and grinding of the material.

23. The method of claim 22, wherein at least one of the mechanical milling and grinding is carried out in a ball mill, a planetary mill, a shaker mill, a crusher and a grinder for time period of at least 5 minutes to 24 hours.

24. The method of claim 1, wherein the contacting of the material dissolves rare earth metal content to form the water soluble derivative and then the water soluble derivative is precipitated as a rare earth metal oxalate, rare earth metal sulfate, rare earth metal-sodium sulfate, rare earth metal phosphate, or rare earth metal fluoride.

25. The method of claim 1 wherein the material comprises magnet scrap or battery scrap.

26. The method of claim 25 wherein the magnet scrap includes shredded non-magnet components.

27. The method of claim 1 wherein the material comprises at least one of grinding swarf, magnet scrap cuttings, polishing byproducts, magnet powders, and magnets derived from manufacturing processes including magnet manufacturing and additive manufacturing processes.

28. A method for use in recycling of a material that includes a metal content to be recovered comprising at least one of a rare earth metal, cobalt, and nickel, wherein the rare earth metal includes at least one of Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, comprising the step of contacting the material and a chemical reagent that includes at least one of an ammonium salt and iron (lll) salt to carry out a mechanochemical reaction in the absence of water or solvent to form a derivative of the at least one rare earth metal, cobalt and nickel.

29. The method of claim 28 wherein the mechanochemical reaction is conducted by at least one of mechanical milling and grinding of the material.

30. The method of claim 29 wherein at least one of the mechanical milling and grinding is carried out in a ball mill, a planetary mill, a shaker mill, a crusher and a grinder for time period of at least 5 minutes to 24 hours.

31. A method for use in recycling of a material that includes a metal content to be recovered, comprising at least one of a rare earth metal, cobalt, and nickel, wherein the rare earth metal includes at least one of Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, comprising the step of contacting the material and an iron (lll) salt reagent to carry out at least one of a liquid phase chemical reaction and a mechanochemical reaction to form a water soluble derivative of the at least one of the rare earth metal, cobalt and nickel.

32. The method of claim 31, wherein the iron (lll) salt contains at least one anion comprising a Cl.sup.−, Br.sup.−, I.sup.−, NO.sub.3.sup.−, HSO.sub.4.sup.−, and SO.sub.4.sup.2−.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1. Powder X-ray diffraction (XRD) pattern of NaNd(SO.sub.4).sub.2.Math.H.sub.2O obtained in Example 1. Vertical bars at the bottom of the plot correspond to calculated Bragg peak positions of NaNd(SO.sub.4).sub.2.Math.H.sub.2O.

(2) FIG. 2. Powder XRD patterns of NaNd(SO.sub.4).sub.2.Math.H.sub.2O obtained in Examples 2a and 2b. Vertical bars at the bottom of the plot correspond to calculated Bragg peak positions of NaNd(SO.sub.4).sub.2.Math.H.sub.2O.

(3) FIG. 3. Powder XRD pattern of NaNd(SO.sub.4).sub.2.Math.H.sub.2O obtained in Example 3. Vertical bars at the bottom of the plot correspond to calculated Bragg peak positions of NaNd(SO.sub.4).sub.2.Math.H.sub.2O.

(4) FIG. 4. Powder XRD pattern of NaSm(SO.sub.4).sub.2.Math.H.sub.2O obtained in Example 4. Vertical bars at the bottom of the plot correspond to calculated Bragg peak positions of the NaSm(SO.sub.4).sub.2.Math.H.sub.2O.

(5) FIG. 5. Powder XRD patterns of Co oxalate obtained in Examples 5a and 5b. Vertical bars at the bottom of the plot correspond to calculated Bragg peak positions of [C.sub.2O.sub.4]Co.Math.2H.sub.2O.

(6) FIG. 6. X-ray fluorescence (XRF) spectrum of Co oxalate obtained in Example 5a. Vertical bars at the bottom of the plot correspond to energies characteristic of cobalt.

(7) FIG. 7. Powder XRD pattern of the magnetic phase (metallic nickel) obtained in Example 6. Vertical bars at the bottom of the plot correspond to calculated Bragg peak positions of Ni.

(8) FIG. 8. Powder XRD pattern of nickel oxalate obtained in Example 6. Vertical bars at the bottom of the plot correspond to calculated Bragg peak positions of [C.sub.2O.sub.4]Ni.Math.2H.sub.2O.

(9) FIG. 9. Powder XRD powder pattern of NaLa(SO.sub.4).sub.2.Math.H.sub.2O obtained in Example 6. Vertical bars at the bottom of the plot correspond to calculated Bragg peak positions of NaLa(SO.sub.4).sub.2.Math.H.sub.2O.

(10) FIG. 10. The magnet scrap material (MSM) obtained by mechanical crushing of used computer hard drives and removing large structural fragments that do not include a magnet as component.

(11) FIG. 11. XRF spectrum of NaNd.sub.0.85Pr.sub.0.15(SO.sub.4).sub.2.Math.H.sub.2O obtained in Example 7. Vertical bars at the bottom of the plot correspond to characteristic energies of Neodymium, Praseodymium and Sulphur.

(12) FIG. 12. Powder XRDr patterns of NaNd.sub.0.85Pr.sub.0.15(SO.sub.4).sub.2.Math.H.sub.2O (b) obtained in Example 7 and NaNd(SO.sub.4).sub.2.Math.H.sub.2O (a) obtained in Example 2. Vertical bars at the bottom of the plot correspond to calculated Bragg peak positions of NaNd(SO.sub.4).sub.2.Math.H.sub.2O.

DETAILED DESCRIPTION OF THE INVENTION

(13) Certain embodiments of the present invention are useful for recycling spent REE-containing magnetic alloys or battery materials to extract critical and/or valuable elements including rare earths, Co or Ni. Illustrative embodiments of the present invention employ liquid phase chemical reactions and/or mechanochemical reactions, which can be performed in the temperature range between 0° C. and 100° C. The mechanochemical processing can include, but is not limited to, ball-milling, shredding, grinding, and/or extruding and combinations thereof. The mechanochemical processing is conducted in the presence of one or more chemical agents selected to convert the recycled material into water soluble intermediates. This processing may be carried out in the absence of, or optionally in the presence of minor amounts, e.g. less than 10 wt. %, of water, or other liquid solvent.

(14) In some embodiments, the mechanochemical step, such as ball milling, is performed first followed by a liquid phase chemical processing step of the solid product obtained from the first step using appropriate liquid phase chemical reactions.

(15) In one illustrative embodiment, iron (III) salt, containing anions such as Cl.sup.−, Br.sup.−, I.sup.−, NO.sub.3.sup.−, HSO.sub.4.sup.− or SO.sub.4.sup.2− is employed as reagent dismantling REE-based alloy to form a mixture of water soluble metal salts, which can be treated with an appropriate reagent such as sodium sulfate or oxalic acid to precipitate sodium (Na)-REE sulfate or REE oxalate, suitable for further conversion into useful products using conventional protocols..sup.25 For example, Sm- or Nd-containing magnetic alloy is converted into water-soluble Sm or Nd salts that can be further transformed into insoluble NaREE(SO.sub.4).sub.2.Math.H.sub.2O compound by the reaction with Na.sub.2SO.sub.4 in aqueous solution, whereby all chemical reactions are carried out in an aqueous solution at the temperature below 100° C. with no addition of further oxidizers as illustrated below.
SmCo.sub.5+13FeX.sub.3=SmX.sub.3+5CoX.sub.2+13FeX.sub.2
SmX.sub.3+2Na.sub.2SO.sub.4+H.sub.2O=NaSm(SO.sub.4).sub.2.Math.H.sub.2O↓+3NaX
Nd.sub.15Fe.sub.77B.sub.8+199FeX.sub.3=15NdX.sub.3+276FeX.sub.2+8{B}
NdX.sub.3+2Na.sub.2SO.sub.4+H.sub.2O=NaNd(SO.sub.4).sub.2.Math.H.sub.2O↓+3NaX
Nd.sub.15Fe.sub.77B.sub.8+45FeX.sub.3+{solid-state milling}=[NdX.sub.3].sub.15[FeB.sub.8][FeX.sub.2].sub.45
[NdX.sub.3].sub.15[Fe.sub.77B.sub.8][FeX.sub.2].sub.45+xH.sub.2O=15NdX.sub.3+45FeX.sub.2+{Fe.sub.77B.sub.8(OH.sub.2).sub.x}↓
NdX.sub.3+2Na.sub.2SO.sub.4+H.sub.2O=NaNd(SO.sub.4).sub.2.Math.H.sub.2O↓+3NaX

(16) In another illustrative embodiment, ammonium salt containing such anions as Cl.sup.−, Br.sup.−, I.sup.−, NO.sub.3.sup.−, HSO.sub.4.sup.− or SO.sub.4.sup.2− is employed as a reagent for dismantling of REE-containing alloy to form a reaction mixture containing a water soluble REE salt, which can be treated with an appropriate reagent, including sodium sulfate or oxalic acid, precipitating NaREE(SO.sub.4).sub.2.Math.H.sub.2O or REE oxalate, suitable for conversion into corresponding metal oxides using conventional protocols reference 27).
Nd.sub.15Fe.sub.77B.sub.8+199NH.sub.4X=15NdX.sub.3+77FeX.sub.2+8{B}+199NH.sub.3+99.5H.sub.2
NdX.sub.3+2Na.sub.2SO.sub.4+H.sub.2O=NaNd(SO.sub.4).sub.2.Math.H.sub.2O↓+3NaX

(17) In another illustrative embodiment, an ammonium salt containing such anions as Cl.sup.−, Br.sup.−, I.sup.−, NO.sub.3.sup.−, HSO.sub.4.sup.− or SO.sub.4.sup.2− is employed as reagent for dismantling of a solid Co-containing magnetic alloy to produce a reaction mixture containing water-soluble Co salt, which after filtration or centrifugation, is treated with an appropriate reagent, including oxalic acid to precipitate Co oxalate suitable for conversion into Co oxide or another valuable compound. Mechanochemical processing (ball-milling) of the Co-containing magnetic alloy-ammonium salt mixture, mentioned above, substantially increases the yield of the final product. The REE content of the starting magnetic material is recovered by treating the insoluble fraction of the reaction mixture with Fe (III) salt in aqueous solution.
3SmCo.sub.5+30NH.sub.4X+30H.sub.2O=15-xCoX.sub.2+[Sm.sub.3Co.sub.xX.sub.2x]↓+30NH.sub.4OH+15H.sub.2
CoX.sub.2+HO(O)C—C(O)OH+2NH.sub.4OH=Co{O(O)C—C(O)O}↓+2NH.sub.4X+2H.sub.2O

(18) Subsequently, after the filtration or centrifugation, the solution formed is treated with an appropriate reagent such as Na.sub.2SO.sub.4 or oxalic acid.
[Sm.sub.3Co.sub.xCl.sub.2x]+9FeX.sub.3=3SmX.sub.3+xCoCl.sub.2+9FeX.sub.2
SmX.sub.3+2Na.sub.2SO.sub.4+H.sub.2O=NaSm(SO.sub.4).sub.2+H.sub.2O↓+3NaX

(19) The precipitated NaREE(SO.sub.4).sub.2.Math.H.sub.2O or REE oxalate can be further converted into corresponding metal oxides using conventional chemical protocols (reference 27).

(20) In another illustrative embodiment, ammonium salt containing such anions as Cl.sup.−, Br.sup.−, I.sup.−, NO.sub.3.sup.−, HSO.sub.4.sup.− or SO.sub.4.sup.2− is employed as reagent for dismantling a solid REE-based battery material to form a reaction mixture containing a water soluble REE salt, which can be treated with an appropriate reagent, including Na.sub.2SO.sub.4 or oxalic acid, precipitating NaREE(SO.sub.4).sub.2.Math.H.sub.2O or REE oxalate, suitable for conversion into corresponding metal oxide using conventional protocols (reference 27). The transition metal component of the battery material remains undissolved and is isolated in the metallic form.
LaNi.sub.5+3NH.sub.4X+3H.sub.2O=LaX.sub.3+5Ni↓+3NH.sub.4OH+1.5H.sub.2
LaX.sub.3+2Na.sub.2SO.sub.4+H.sub.2O=NaLa(SO.sub.4).sub.2.Math.H.sub.2O↓+3NaX

(21) In another illustrative embodiment, magnetic scrap material, which is obtained by mechanical crushing of used computer hard drives, has been treated with iron (III) salt, containing anions such as Cl.sup.−, Br.sup.−, I.sup.−, NO.sub.3.sup.−, HSO.sub.4.sup.− or SO.sub.4.sup.2− to form a mixture of water soluble metal salts, which can be treated with an appropriate reagent such Na.sub.2SO.sub.4 or oxalic acid, precipitating NaREE(SO.sub.4).sub.2.Math.H.sub.2O or REE oxalate, suitable for further conversion into useful products using conventional protocols (reference 27).

(22) The characterization of the reaction products by powder X-ray diffraction (XRD) analysis was carried at room temperature using a PANalytical powder diffractometer utilizing Cu-Kα.sub.1 radiation with a 0.02° 2θ step in the range of Bragg angles 2θ from 10° to 80°. The X-ray fluorescence (XRF) analysis was carried out in a Brooker M4 Tornado spectrometer with 50 microA/200V X-ray beam and the spot size of 25 microns. XRF spectra evaluation performed using the Mineral Standard Database, incorporated into spectrometer software. The yields of products were calculated based on actual amounts of the isolated materials.

(23) The ball milling of materials was performed in a SPEX 8000M shaker mill in air using 50 ml hardened-steel vial with 20 g (g=grams) of steel balls (two large balls weighing 8 g each and four small balls weighing 1 g each).

(24) The practical applications of the invention was demonstrated using commercial materials: Nd.sub.15Fe.sub.77B.sub.8 (lumps), SmCO.sub.5 (powder) and LaNi.sub.5 (powder), which were purchased from Alfa Aesar and used as received.

(25) The magnet scrap material (MSM, FIG. 10), obtained by mechanical crashing of used computer hard drives and removing large structural fragments, which do not include magnets as component, has been utilized for testing the developed recycling protocols on a real-life object. The recoverable REE content in this MSM was determined by its complete dissolution in the concentrated hydrochloric acid and subsequent precipitation of NaREE(SO.sub.4).sub.2.Math.H.sub.2O from the solution formed using an excess of Na.sub.2SO.sub.4.

(26) The following examples are offered to further illustrate the invention in more detail without limiting the scope of the invention.

Example 1

(27) 1.0 g of Nd.sub.15Fe.sub.77B.sub.8 (0.15 mmol) permanent magnet alloy and 4.9 g (30.10 mmol) of anhydrous FeCl.sub.3 were combined with 150 ml of water and the slurry formed was brought to a boil (about 100° C.) while stirred with a magnetic stirrer. The starting alloy dissolved within 60 min. The heating continued for additional 30 min. The solution was left stirring at room temperature overnight, then it was filtered through a glass-frit. Subsequently, water was partially evaporated to obtain 50 ml of the clear solution. 1.2 g of anhydrous Na.sub.2SO.sub.4 was added to the latter at 100° C. Na.sub.2SO.sub.4 quickly dissolved and an off-white precipitate started to form within a few minutes. 0.78 g of the water-insoluble product was filtered off and dried in air. The material was identified as NaNd(SO.sub.4).sub.2.Math.H.sub.2O using XRD (FIG. 1). The isolated yield of NaNd(SO.sub.4).sub.2.Math.H.sub.2O was 90% of the theoretically expected amount. Note: Nd.sub.15Fe.sub.77B.sub.8 does not react with pure water even upon boiling.

Example 2

(28) (a) 0.66 g of Nd.sub.15Fe.sub.77B.sub.8 (0.10 mmol) and 0.74 g (6.8 mmol) of anhydrous FeCl.sub.3 were ball-milled in a Spex 8000M shaker mill for 24 hours. Distinct formation of metallic iron has been observed in the milled sample using XRD. Subsequently, the obtained powder was combined with 100 ml of water and the slurry formed was brought to a boil (100° C.) and stirred at that temperature for one hour. The reaction mixture turned blue first, then it became light brown. Stirring continued at room temperature overnight, then the solution was filtered through a glass frit. The obtained liquid was heated up to 80° C. and combined with 1 g of anhydrous Na.sub.2SO.sub.4. Na.sub.2SO.sub.4 quickly dissolved and an off-white precipitate started to form within a few minutes. 0.5 g of the solid product was filtered off and dried in air. The material was identified as NaNd(SO.sub.4).sub.2.Math.H.sub.2O using XRD analysis (FIG. 2). The isolated yield of NaNd(SO.sub.4).sub.2.Math.H.sub.2O was 87% of the theoretically expected amount.

(29) (b) A similar experiment was performed with 1.0 g of Nd.sub.15Fe.sub.77B.sub.8 (0.15 mmol) and 1.1 g (6.8 mmol) of anhydrous FeCl.sub.3 in aqueous solution without a preceding milling step. Also in this case, NaNd(SO.sub.4).sub.2.Math.H.sub.2O formed. However, its yield was only 0.43 g, i.e. 49% of the theoretically expected amount.

Example 3

(30) 1.0 g of Nd.sub.15Fe.sub.77B.sub.8 (0.15 mmol) and 1.6 g (30 mmol) of anhydrous NH.sub.4Cl were combined with 100 ml of water and the slurry formed was brought to a boil (about 100° C.) while stirred with a magnetic stirrer. The stirring at about 100° C. continued for 4 hours, then at room temperature overnight. After the filtration through a glass frit, water was partially evaporated to obtain 50 ml of a clear solution. 1.2 g of anhydrous Na.sub.2SO.sub.4 was added to the latter at about 100° C. The sulfate quickly dissolved and off-white precipitate started to form within a few minutes. The slurry formed was kept at about 80° C. for 1.5 hours. 0.70 g of a solid product was filtered off and dried in air. The product was identified as NaNd(SO.sub.4).sub.2.Math.H.sub.2O using XRD analysis (FIG. 3). The isolated yield of NaNd(SO.sub.4).sub.2.Math.H.sub.2O was 81% of the theoretically expected amount.

Example 4

(31) 1.0 g of SmCo.sub.5 (2.20 mmol) and 4.9 g (29.0 mmol) of anhydrous FeCl.sub.3 were combined with 100 ml of water and the slurry formed was stirred using a magnetic stirrer at room temperature for one hour. SmCo.sub.5 dissolved within 60 min. Water was evaporated and 5.42 g of the remaining solid material was re-dissolved in hot water and filtered through a paper filter to obtain a clear pink solution. The residue on the filter was washed with 50 ml of water. Subsequently, the pink solution was heated up to 80° C. and 1.25 g of anhydrous Na.sub.2SO.sub.4 was added. The solution had been stirred at 80-100° C. until precipitation started.

(32) The solid formed was filtered off using a glass frit. After drying in air it was identified as NaSm(SO.sub.4).sub.2.Math.H.sub.2O using XRD analysis (FIG. 4). The isolated yield of NaSm(SO.sub.4).sub.2.Math.H.sub.2O was 0.63 g, i.e. 80% of the theoretically expected amount.

Example 5

(33) 1.0 g of SmCo.sub.5 (2.20 mmol) and 1.68 g (31.4 mmol) of anhydrous NH.sub.4Cl were ball-milled for 6 hours in Spex 8000M shaker mill as described above. Prior to ball milling, the sample was loaded in the vial in air or under argon. After ball milling, the 2 g of the powder formed by the mechanochemical solid state reaction of milling were combined with 100 ml of water and heated at about 100° C. for 4 hours. Next, the magnetic material still present in the reaction mixture was separated from the solution formed using a strong permanent magnet. It was identified as SmCo.sub.5, thus 65% (0.65 g) of SmCo.sub.5 has reacted with NH.sub.4Cl. The solution was filtered and water-soluble Co content was precipitated using oxalic acid. The yield of Co-oxalate (FIGS. 5 and 6) was 77% calculated using the reacted SmCo.sub.5 material as base.

(34) A similar reaction that did not include the ball-milling step produced Co-oxalate in only 27% yield, based on the reacted material. Also in this case, the full dissolution of the magnetic phase was not achieved.

Example 6

(35) 1.0 g of LaNi.sub.5 (2.3 mmol) and 1.7 g (31.77 mmol) of anhydrous NH.sub.4Cl were combined with 50 ml of water. The slurry formed was brought to a boil (about 100° C.) while stirred with a magnetic stirrer. The heating continued for 6 hours, then the reaction mixture was left at room temperature overnight. A black magnetic phase (0.6 g) was removed using a strong permanent magnet. Subsequently, the liquid phase was filtered and brought to a boil (about 100° C.). The hot solution was combined with 1.3 g of anhydrous Na.sub.2SO.sub.4, which quickly dissolved. A precipitate started to form within a few min. It was filtered off and dried in air. An additional amount of a solid material was precipitated from the remaining filtrate using 1.6 g of oxalic acid. According to the XRD analysis the magnetic material was Ni-metal (FIG. 7) and the oxalate was Ni oxalate (FIG. 8). 0.83 g of NaLa(SO.sub.4).sub.2.Math.H.sub.2O, 96% of the theoretically expected amount, was isolated and characterized using XRD (FIG. 9).

Example 7

(36) 3.7 g of magnetic scrap material (MSM, FIG. 10) were dissolved in 35 ml of concentrated HCl upon heating. The reaction mixture formed was diluted with 115 ml of water, filtered to remove a minor amount of insoluble materials and neutralized using aqueous NaOH to obtain solution with acidic pH between 1 and 2. Subsequently, this solution was brought to a boil and combined with 5.1 g of anhydrous Na.sub.2SO.sub.4 dissolved in 20 ml of water. Off-white precipitate started to form within a few minutes. The slurry formed was kept at about 80° C. for 1.5 hours, then 2.05 g of a solid product was filtered off and dried in air. The product composition of NaNd.sub.0.85Pr.sub.0.15(SO.sub.4).sub.2.Math.H.sub.2O, was identified by combination of XRF (FIG. 11) and XRD analyses.

(37) XRD data confirmed the structure of the obtained triple salt similar to NaNd(SO.sub.4).sub.2.Math.H.sub.2O, obtained in examples 1, 2, and 3 described above. Partial substitution of Nd atoms with larger size Pr in its structure leads to increase of lattice parameters, and therefore, shifts Bragg reflections toward lower 2θ (FIG. 12). The isolated yield of NaNd.sub.0.85Pr.sub.0.15(SO.sub.4).sub.2.Math.H.sub.2O was used as reference (taken as 100%) for example 8.

Example 8

(38) 1.0 g of MSM (FIG. 10) and 4.9 g (30.10 mmol) of anhydrous FeCl.sub.3 were combined with 100 ml of water and the slurry formed was brought to a boil (about 100° C.) while stirred with a magnetic stirrer. The heating continued for additional 60 min. The reaction mixture was cooled down and left stirring at room temperature overnight. Then, it was filtered through a glass frit. Subsequently, water was partially evaporated to obtain 50 ml of the solution. 1.5 g of anhydrous Na.sub.2SO.sub.4 was added to the latter at about 100° C. The added sulfate quickly dissolved and an off-white precipitate started to form within a few minutes. The solid product was filtered off and dried in air. Using XRD, the material was identified as NaNd.sub.0.85Pr.sub.0.15(SO.sub.4).sub.2.Math.H.sub.2O that was identical to that formed in Example 7. The isolated yield of NaNd.sub.0.85Pr.sub.0.15(SO.sub.4).sub.2.Math.H.sub.2O was 0.41 g, i.e. 77% of the amount collected in Example 7.

(39) Although the present invention has been described with respect to certain particular illustrative embodiments, those skilled in the art will appreciate that modifications and changes can be made thereto without departing from the spirit an scope of the invention as set forth in the appended claims.

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