Processing method of micro production wastes of constant magnets

IPC classes for russian patent Processing method of micro production wastes of constant magnets (RU 2469116):

C22B7 - Working-up raw materials other than ores, e.g. scrap, to produce non-ferrous metals or compounds thereof

C22B59 - Obtaining rare earth metals

C22B5/04 - by aluminium, other metals, or silicon

C22B3/06 - in inorganic acid solutions

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FIELD: metallurgy.

SUBSTANCE: method involves oxidation of micro production wastes at temperature of 550-650°C in air atmosphere for destruction of crystal latitude Nd₂Fe₁₄B so that Fe₂O₃, Nd₂O₃, Fe₂B is formed and moisture and oil is removed. Then, anhydrous fluorides of rare-earth metals are obtained and their metallothermic reduction is performed for production of constant magnets. After oxidation from oxidated microwastes is completed, rare-earth metals are leached with nitric acid with concentration of 1-2 mol/l at temperature of 20-80°C. Obtained nitrate solutions containing rare-earth metals and impurity elements are processed with solution of formic acid with extraction of formiates of rare-earth metals in the form of the deposit cleaned from impurity elements, which includes iron, aluminium, nickel, cobalt, copper and other transition metals.

EFFECT: regeneration of rare-earth metals from production wastes of magnets and obtaining raw material containing rare-earth metals for reutilisation in production of rare-earth constant magnets.

2 cl, 2 tbl, 7 ex

The technical field to which the invention relates.

The invention relates to the field of metallurgy, in particular to methods of producing alloys of rare earth and transition metal doped from waste magnetic production caused by grinding magnets (I) and contaminated mostly lubricant-coolant (coolant), native oxides, materials selfinsurance (SiC, Al₂O₃with the aim of re-use in the production of magnets based on rare-Fe-B. Main REE upon receipt of the magnets are neodymium Nd, and alloying of REM enhancing the basic magnetic characteristics of the magnets, praseodymium Pr, dysprosium Dy, terbium Tb.

The level of technology.

The production of permanent magnets based on rare-Fe-B is to receive the first stage of REM alloys-Fe-B-alloying additives. Further, the alloy is crushed to the size of the domain (3-5 microns), the powder is pressed in a magnetic field, pressing is sintered in a vacuum furnace, sintered billet polished in size selfinstruction of corundum, CBN, diamond and part is subjected to application. To prevent overheating and oxidation of the workpieces, the grinding is carried out with the use of coolant, which use emulsions of different oils with water. Slipperoo collected on magnetic separators, grinders and send the Deposit. I chemical composition close to the composition of the permanent magnets and contain: 22-26 wt.%. REE, 50-55 wt.%. Fe and alloying metals (Co, Ti, Al), 10-30% wt. moisture, up to 5% wt. oxygen, up to 5-7% wt. carbon (in the form of oils), less the amount of other impurities: SiC, Al₂O₃etc. During storage I oxidized and the oxygen content increases to 10-15% wt.

The number of the resulting I is 15-40 wt.%. from the mass of the magnets and depends on many factors, so they recycled for re-use expensive neodymium and expensive alloying additives (Dy, Tb) is an important task, both from an economic and environmental sides. The number of known methods of processing waste magnetic production, is presented below.

In particular, the proposed chloride method for the extraction of neodymium from scrap metal [1], based on the dissolution of the scrap material Nd-Fe in hydrochloric acid followed by filtration. From the filtrate by addition of HF precipitated fluoride neodymium.

A known method for the recovery of neodymium from grinding swarf containing iron [2], based on the dissolution of metallic iron and neodymium in acetic acid with the formation of acetates: [Fe₃(CH₃Soo)₆](CH₃Soo)₆and Nd(CH₃Soo)₃. Neodymium is recovered from the resulting solution by precipitation in the form of fluoride. Oxide jelly is a (III) in acetic acid is not soluble, therefore, it is filtered at the stage of obtaining acetates of neodymium and iron.

In [3] proposed a method for allocation of REM from I the production of permanent magnets, based on receiving from I carbides of rare-earth metals and iron by leaching them with sulfuric acid to obtain neodymium sulfate, further presidenial sulfate neodymium and its dissolution, precipitation of oxalates neodymium, their calcination to the oxide of neodymium and fluoridation.

There is also a sulfate method of extraction of neodymium from the I production of magnets Nd-Fe-B [4]. To highlight neodymium I dissolve in sulfuric acid. The mass ratio of H₂SO₄to the mass of waste 2:1 is sufficient for complete dissolution as rare-earth metals, and iron and prevent oxidation of Fe to Fe³⁺. Neodymium precipitated from the solution with an aqueous solution of ammonia in a well-filtered double sulfates - Nd₂(NH₄)₂(SO₄)₄·8H₂O or (NH₄)Nd(SO₄)₂·4H₂O. While the iron remains in solution. The precipitate of sulphate of neodymium translate into fluoride by treating it with a solution of HF. Conversion occurs most fully when the ratio of HF:dual salt=1:1. The amount of water used should be 10 to 20 times the amount of salt and the precipitate fluoride NdF₃easily filtered if the salt we use the ü water containing HF. The precipitate fluoride REM has the following chemical composition: 23,82% Nd, 0,353% Fe, 4.7% of SO₄^2-, 0.4% of NH₄⁺. The total degree of extraction of rare-earth metals by this method is about 80%.

Royal solutions, saturated with sulphate of iron and other impurities, is treated with 30% solution of H₂O₂for precipitation of iron as jarosite composition (NH₄)Fe₃(SO₄)₂(OH)₆. The temperature of deposition of 90°C, the deposition time is 6 hours. The almost complete precipitation of Fe occurs after 3 hours of treatment. The extraction of Fe in the jarosite is not less than 90%.

The disadvantages of the method are: selective extraction of neodymium, which leads to a high consumption of reagents, going to the dissolution not only of neodymium and iron, the use of expensive H₂O₂for precipitation of iron as jarosite from sulfuric acid aqueous solution, and hence a large number of acidic liquid waste requiring further neutralization. In addition, accumulated waste, stored for several years, oxidized, and iron (III) under this scheme will be to follow along with neodymium.

The closest in technical essence is anhydrous fluoride method of recycling magnetic production [5]. The method includes the operation of drying I, oxidation at 550-650°C, magnetic separation of a mixture of the oxide is in and subsequent fluorination of elemental fluorine at temperatures of 200-300°C. The mixture of fluorides metallothermic restore secondary way of obtaining ligatures REE-Fe and magnetic alloys based on NdFeB.

Drying of I is carried out in vacuum at a residual pressure of about 1 mm Hg to a residual moisture content of not more than 0.5%. During vacuum drying I at a temperature of 70-90°C removes only the moisture and oil in these conditions does not evaporate. The decrease in the concentration of moisture in I leads to a decrease in temperature subsequent oxidation of I. Oxidation of the dried waste conduct secondary way by local initiation of the reaction using electric blasting in the flowing air. When this is heated throughout and partially oxidized mass to a temperature of 550-650°C. during the reaction, which lasts for 150-240 seconds, is the sublimation and oxidation of oils to carbon oxides and water. Non-magnetic component of the I - particles selfinsurance, such as corundum (aluminium oxide), Elbor, organic adhesive, partially removed from the waste by using magnetic separation. The obtained magnetic fraction of the mixture of oxides is directed to the fluorination of elemental fluorine at a temperature of 200-300°C. this ensures the conversion of the oxides in the fluoride is not less than 95%. In the process of fluorination is fine purification of the mixture of oxides is tons of carbon, boron and silicon due to the formation of volatile fluorocarbons, TRIFLUORIDE boron and silicon tetrafluoride. The mixture of fluorides metallothermic restore secondary way of obtaining ligatures REE-Fe(Co) or magnetic-based alloys, Nd-Fe-B.

Disadvantages of the method: the use of elemental fluorine, and therefore, special requirements for equipment recycling magnetic production, high adiabatic process temperature metallotrejderskogo recovery of a mixture of fluorides - 3000°C or more - leads to the release of the reaction products from the crucible and the lower output of the alloys or alloys in ingot, and to decrease it in the mixture of fluorides add fluoride, neodymium and calcium powder metal iron, ferroboron and alloying components.

The objective of the invention is the regeneration of REE (Nd, Dy, Tb and others) from the I production of magnets based on NdFeB order to obtain REE-containing raw materials for reuse in the production of rare earth permanent magnets.

The essence of the invention.

This object is achieved in that the method of processing the I production of permanent magnets based on Nd-Fe-B containing alloying elements Dy, Tb, and also accompanying the neodymium praseodymium Pr, includes the following stages:

- oxidation of waste;

- leaching of neodymium, etc the other rare-earth metals from oxidized I nitric acid;

- separation of insoluble Fe₂O₃, oxides of the alloying components of the transition metals (Ti, Co, Zr, Hf), SiC, Al₂O₃filtering;

- precipitation from nitrate solutions of sparingly soluble formate neodymium and other rare-earth metals;

- washing the precipitate with a solution of formic acid to remove residual amounts of dissolved iron formate, aluminum, cobalt, titanium, and others;

- calcination formate neodymium and other rare-earth metals to oxides at a temperature of 700-800°C in air, the fluoridation of REE oxides and further metallothermic recovery with getting ligatures REE-Fe or alloys based on NdFeB, a manufacturer of permanent magnets according to known methods.

Since the content of Nd with respect to the total content of all REM usually exceeds 80%, and the properties of the main alloying REM (Dy, Tb, Pr) is close to the properties of Nd in the future under Nd understood the contents of all REE.

The inventive method is as follows.

Oxidation of I is conducted in air at a temperature of 550-650°C [5]. The oxidation process required for the destruction of the crystal lattice, remove the oil. As a result of oxidation are formed such compounds: Nd₂O₃(REM₂About₃), Fe₂O₃and Fe₂B. At the same time achieve maximum transfer of iron in insoluble form oxide Fe 2O₃that when leaching with nitric acid remains in the insoluble residue, and Fe (III), in contrast to Fe (II), is a convenient form in further stages of processing.

Oxides of neodymium (REM) from oxidized I leached with dilute nitric acid solution with a concentration of 2-3 mol/l and an excess of up to 30% at a temperature of 30-40°C. under these conditions, the degree of extraction of rare earth metals is 94-96%. In the solution passes partially and iron from ferroboron (Fe ferroboron is 16% of the total), whereas almost all of the iron, in the I in the form of iron oxide (III)remains in the sediment and can be re-used to produce magnetic alloys:

Nd[REM]₂O₃+6HNO₃=2Nd[REM](NO₃)₃+3H₂O,

3Fe₂B+16HNO₃=6Fe(NO₃)₃+8H₂O+4NO↑+3V↓.

The of neodymium nitrate solution precipitated with formic acid in the form of sparingly soluble formate neodymium Nd(HCOO)₃, while the resulting formate iron Fe(NCOA)₃is a soluble compound remains in solution. The precipitate is washed with a solution of formic acid to remove residual Fe(NCOA)₃:

Nd[REM](NO₃)₃+SOON=Nd[REM](HCOO)₃↓+3HNO₃,

Fe(NO₃)₃+SOON=Fe(NCOA)₃+3HNO₃.

Formate is not the Dima calcined to Nd ₂O₃at temperatures of 700 to 750°C in air to the oxide of neodymium Nd₂O₃or are hydroperiodide with obtaining neodymium TRIFLUORIDE NdF₃·nH₂O, dried and calcined at a temperature of 400-450°C To produce anhydrous NdF₃. Hydroperiodide can be done and anhydrous HF at a temperature of 300-400°C To produce NdF₃. Further magnetic alloys based on Nd-Fe-B or ligatures type REE-Fe(Co) is carried out by secondary calcium thermal recovery by a known method [5].

The invention is illustrated by the following examples.

Example 1. The effect of the concentration of nitric acid on the degree of dissolution of the oxidized components of I at a temperature of 25°C.

Dissolved individually the main components of oxidized I - Fe, Fe₃O₄, Fe₂O₃, Fe₂B, and are themselves oxidized I - 100 ml of nitric acid of different concentrations (0.5-5 mol/l). This amount of acid in each case was taken to preserve the acidity of the solution before and after the experiment. The process was carried out at a temperature of 25°C for 1 hour. The mass of a sample in each experiment was 1 year After leaching solutions were filtered on a paper filter (blue ribbon), the precipitate was washed with a solution of 0.1 mol/l HNO₃and the combined filtrate analysis is Aravali on the contents of Fe and Nd.

The results of experiments on the solubility of Fe₂O₃, Fe₂B, oxidized I in solutions of HNO₃different concentrations are presented in table 1.

93,0

Table 1
The degree of dissolution of the oxidized components of I in solutions of nitric acid of different concentrations at 25°C, % wt.
Component	The acid concentration, mol/l
0,5	1,0	1,5	2,0	2,5	3,0	4,0	5,0
neodymium	to 70.2	85,1	91,2	94,1	a 94.2	95,5	95,6	95,6
α-Fe	79,5	82	85,4	86,1	91,0	93,0	93,0
α-Fe₃O₄	83,3	83,0	89,6	90,2	br93.1	95,7	95,6	a 94.2
α-Fe₂O₃	0,15	0,20	0,24	0,28	0,31	0,35	0,37	0,4
Fe₂B	70,0	73,0	77,5	81,7	82,6	of 83.4	85,6	86,7
ΣFe	11,2	12,4	12,9	13,9	14,1	14,2	15,0	16,7

The experimental results show that the degree of dissolution of metallic iron and oxide of Fe₃O₄nitric acid is quite high.

When dissolved and iron oxide (III) at a temperature of 25°With the degree of dissolution of iron insignificant in the whole range of investigated concentrations and with increasing concentration of nitric acid of from 0.5 to 5 mol/l increases slightly. When the concentration of HNO₃1 mol/l dilution of the Fe₂O₃is 0.2%and at a concentration of 5 mol/l to 0.4%.

When dissolved ferroboron, the degree of dissolution of iron varies depending on the concentration of HNO₃slightly. Increasing the concentration of HNO₃in the solution to 1 mol/l leads to a sharp increase in the rate of dissolution of iron to 73%. With further increase in acid concentration to 5 mol/l, the degree of dissolution of iron increases to 87%.

When dissolved oxidized I in nitric acid with a concentration of 1 mol/l dilution of the neodymium is 85%, and iron and 12.4%. With further increase in the concentration of HNO₃to 3 mol/l dilution of the neodymium smoothly increases from 85% to 95%, and iron slightly to 14.2% at 25°C.

Supplier of iron in the solution is ferroboron, the solubility of which according to table 1 high in the studied range of concentrations of nitric acid and varies from 73% to 86.7%.

Example 2. The effect of the concentration of nitric acid on the degree of dissolution of the oxidized components of I at a temperature of 80°C.

In this series of experiments investigated the process of dissolution of the individual major components of oxidized I - Fe, Fe₃O₄, Fe₂O₃Fe₂B - and themselves oxidized I in nitric acid is different concentrations (0.5-5 mol /l) of the same volume of 100 ml as in example 1. The process was carried out at a temperature of 80°C for 1 hour. Its weight was about 1 year After leaching solutions were filtered on a paper filter (blue ribbon), the precipitate was washed with a solution of 0.1 mol/l HNO₃and the combined filtrate was analyzed for Fe and Nd.

The results of experiments on the dissolution of Fe, Fe₃O₄, Fe₂O₃Fe₂B, oxidized I in solutions of HNO₃different concentrations are presented in table 2.

Table 2
The degree of dissolution of the oxidized components of I in solutions of nitric acid of different concentrations at 80°C, % wt.
Component	The acid concentration, mol/l
0,5	1,0	1,5	2,0	2,5	3,0	4,0	5,0
neodymium	78,5	88,0	91,5	to 97.1	97,9	99,0	99,0	99,0
α-Fe	80,4	is 83.8	86,4	87,2	92,6	94,0	95,4	96,0
α-Fe₃O₄	84,3	84,6	90,2	92,0	94,5	96,4	96,6	95,8
α-Fe₂O₃	0,55	0,65	0,70	1,50	1,75	2,7	4,8	6,9
Fe₂B	71,6	78,5	82,4	85,1	86,2	88,2	90,5	91,8
ΣFe	40,6	52,0	55,8	58,0	59,0	62,0	68,6	71,4

From the data presented in table 2, it follows that the temperature increase of the process of dissolution of iron oxide (III), Fe₂O₃80°C leads to an increase in the degree of dissolution of iron varies. In the region of low concentrations of HNO₃0.5 to 2 mol/l, the degree of dissolution of iron is low at 0.3 and 0.7%, respectively. With further increase in the concentration of HNO₃to 5 mol/l, the degree of dissolution of iron is increased to 7%.

The temperature increase of the dissolution process ferroboron up to 80°C does not change the nature of the dependence of the degree of dissolution of iron, but the total degree of dissolution of iron is significantly increased. When the concentration of HNO₃1 mol/l, it is 77%, and with 5 mol/l - 86%.

When the temperature of the process of dissolution of the oxidized I-80°C degree of dissolution of neodymium reaches 96% at a concentration of HNO₃2 mol/l, and the degree of dissolution of iron is increased to 14.4% at a concentration of HNO₃1 mol/l and up to 15-16% at 5 mol/L.

Conclusion: Thus, the concentration of HNO₃in solution 2-3 mol/l and a temperature of 25-35°C are optimal for the dissolution of I, since under these conditions the solubility of iron oxide (III) is still small (<1%), and neodymium is on is at least 95-96% at 25°C.

Example 3. The effect of temperature and pH on the speed and completeness of the deposition Nd(HCOO)₃.

The deposition process formate of neodymium nitrate solutions can be expressed by the following stoichiometric equations:

Nd[REM](NO₃)₃+SOON - Nd[REM](NCOA)₃↓+3HNO₃,

2HNO₃+SOON=NO↑+NO₂↑+2CO₂↑+3H₂O.

The deposition was carried out at 60 to 90°C. the Volume of each of the samples of the original nitrate solution was 55 ml, the concentration of Nd[REM](NO₃)₃76 g/l, residual concentration of nitric acid in the solution is 1.3 - 1.5 mol/l For nitrate solution was added formic acid brand "reagent grade", in excess of 75%, 85% and 100%.

In the investigated temperature range of 60-80°C, the deposition process was absent, because the nitric acid and formic not yet begin to interact with each other.

In the range of 85-90°C redox reaction between the acid proceeds rapidly, and with an excess of 70-100% formic acid thermal effect of redox reaction initiates the transition of neodymium nitrate in formate.

With fewer formic acid the formation of Nd(HCOO)₃does not leak - neodymium remains in solution in the nitrate form Nd(NO₃)₃.

In the study according to the degree of extraction of neodymium in the formate of the solution from isbidirectional acid were obtained the following results:

- with an excess of formic acid 70%, the degree of extraction of neodymium in formate was 72% wt.;

- with an excess of formic acid 85%, the degree of extraction of neodymium in formate was 85% wt;

- with an excess of formic acid 100% degree of extraction of neodymium in formate 96% wt.

With further increase of the excess formic acid the recovery of neodymium from solution in the form of insoluble salts of formate neodymium remained at 96%.

Therefore, the most optimal for the extraction of neodymium in the form muraveinikakh salt is a 100%excess HCOOH.

To study the effect of pH solution on the deposition Nd(HCOO)₃from nitrate leaching solutions slag process was carried out at the pH of the solution from 1 to 5. The sediment moravcikova neodymium at pH 1-2. The sediment is well filtered. At pH 3-5 is a joint deposition of neodymium and iron. Iron precipitates as hydroxide by hydrolysis of the formate iron Fe(NCOA)₃:

Fe(NCOA)₃+H₂O↔Fe(OH)(NCOA)₃+HCOOH,

Fe(OH)(HCOO)₂+H₂O↔Fe(OH)₂(HCOO)+HCOOH,

Fe(OH)₂(HCOO)+H₂O=Fe(OH)₃↓+HCOOH.

The same pattern is observed when used as a precipitator ammonium formate NH₄HCOO. Sediment the red color.

Example 4. The research process hydroperiodide of Formia is and neodymium with obtaining neodymium fluoride.

The mass of the original hanging formate neodymium was 3, Volume hydrofluoric acid concentration of 2.55% took at the rate of 10%, 30% and 50% excess. The process was performed under continuous stirring for 1 hour at a temperature of about 80°C. these conditions are chosen after a study of the kinetics of the process hydroperiodide compounds of neodymium depending on temperature. Continuous stirring is necessary for the most complete conversion of formate neodymium in fluoride because the initial and final system heterophony, formate and neodymium fluoride are trudnorastvorimye connections. Hydrofluoric acid is stronger than formic, so there is a replacement of formate ion to fluoride ion in the sediment. The reaction is shown below:

Nd[REM](HCOO)₃↓+3HF=Nd[REM]F₃↓+SOON.

Drying the precipitate fluoride, neodymium Nd[REM]F₃was carried out at 110°C. the Mass of the samples was of 2.21 g, 2,19 g and 2.18 g, respectively, with increasing excess hydrofluoric acid. The samples were subjected rettino-fluorescent analysis. The results of the experiments are the following:

- with an excess of hydrofluoric acid 10% degree of fluorination Nd[REM](HCOO)₃96%;

- with an excess of hydrofluoric acid and 30% degree of fluorination Nd[REM](HCOO)₃98,5%;

- with an excess of hydrofluoric acid 50% degree of fluorination

Nd[REM](HCOO)₃amounted to 999%.

Based on the obtained data pereosazhdeniya of neodymium fluoride from formate neodymium recommended when 30-50%excess hydrofluoric acid.

The output of neodymium nitrate solution of example 3 in fluoride was 96%.

Example 5. The annealing formate neodymium obtaining neodymium oxide.

Drying sludge formate neodymium Nd[REM](HCOO)₃was carried out at 90-110°C. the mass of the precipitate amounted to 3.41, the course of Annealing was performed at 800°C in a current of air. In the absence of air flow over the oxidizable material temperature in the layer proklinaemogo formate neodymium reduced, which leads to incomplete removal of carbon from the system. The process temperature is selected based on derivatograph decomposition of formate neodymium to oxide. The stoichiometric reaction is as follows:

2Nd[REM](HCOO)₃→Nd[REM]₂O₃+3C+3CO₂↑+3H₂O.

The mass of the obtained oxide of neodymium was 1,95, the Output neodymium was from nitrate solutions of example 3 in the oxide was 96%.

Conclusion: Obtained according to examples 4 and 5, a fluoride or oxide of neodymium can be used as main components in producing the magnetic alloys, Nd-Fe-B alloys Nd-Fe with calcium thermal recovery [7].

Example 6. Obtaining magnetic alloy of neodymium fluoride.

To obtain alloy 30Nd-1B-69Fe (wt.%) [7] 1340 g of neodymium TRIFLUORIDE (neodymium - 960 g), 228 g of iron TRIFLUORIDE (iron - 1104 g), 32 g of boron and 1104 g of iron powder is mixed with 1733 calcium chips, placed in a crucible and sealed reactor. Excess calcium 10% of stoichiometry. The neodymium TRIFLUORIDE is obtained from I by examples 1-4, iron TRIFLUORIDE - fluoridation of iron oxides with gaseous fluorine.

The neodymium TRIFLUORIDE has the following particle size distribution: fraction (+2.0 mm) 24%, fraction (-2,0)-(+0,08) mm 44% and the fraction (-0,08) mm 32%. The restoration is carried out at the local initiation of reaction electric spiral. Chemical analysis of alloy shows the content of neodymium - 28%, boron - 1,03%, iron - rest. Access to the ingot was 98%, the mass of the ingot 3135,

Example 7. Obtaining magnetic alloy of neodymium oxide.

To obtain alloy 30Nd-1B-69Fe (wt.%) [8] 1120 g of oxide neodymium (neodymium - 960 g), 2228 g TRIFLUORIDE iron (iron - 1104 g), 32 g of boron and 1104 g of iron powder is mixed with 1890 calcium chips, placed in a crucible and sealed reactor. Excess calcium 20% of stoichiometry. The neodymium oxide is obtained from I by examples 1-5, iron TRIFLUORIDE - fluoridation of iron oxides with gaseous fluorine.

The neodymium oxide has the following particle size distribution: fraction (+2.0 mm) 34%, fraction (-2,0)-(+0,08) mm (36%) and fraction (-0,08) mm 30%. The restoration is carried out at the local initiation of reaction electric spiral. Chemical analysis of alloy indicates the content is the use of neodymium - 27,8%, boron - 1,0%, iron - rest. Access to the ingot was 96%, the mass of the ingot 3072,

Sources of information

1. Recovery of neodymium from scrap. Matsumoto, Yasuhide, Takahashi, Ichita (Scowa Denko K.K.) Jpn. KokaiTokkyoKoho JP 01 21,022 (C1. C22B 59/00), 24 Jan. 1989, Appl. 87/174,785, 15 Jul 1987; 3 pp.

2. U.S. patent No. 5362459. The recovery of neodymium iron containing grinding chips. - 1994.

3. Mol, Vshivkov, Vpositive and other Development of technology for recycling of permanent magnets based on Nd-Fe-B / XVI conference, Suzdal.

4. J.W.Liman, G.R.Palmer Neodimium and Iron Recovery from Nd-Fe-B Permanent Magnet Scrap // U.S.Department of the Interior Bureau of Mines // Salt Lake City Research Center: Utah. 1988 - 15 p.

5. RF patent №2111833. The method of processing of I from the production of permanent magnets. - 1998.

6. U.S. patent No. 6383400. Method For Reducing Nitrate And/or Nitric Acid Concentration In An Aqueous Solution. - 2002.

7. RF patent №2031464. The method of obtaining magnetic alloys based on rare-earth and transition metals. - 1995.

8. RF patent №2060290. The method of obtaining magnetic alloys. - 1996.

1. The method of processing of I from the production of permanent magnets Nd-Fe-B, including the oxidation of I at a temperature of 550-650°C in an atmosphere of air for the destruction of the crystal lattice of Nd₂Fe₁₄B with the formation of Fe₂O₃Nd₂O₃, Fe₂B and remove moisture and oil, anhydrous fluorides of rare-earth metals and metallothermic them restore the ie for the manufacture of permanent magnets, characterized in that after oxidation of I spend REE leaching of oxidized I nitric acid with a concentration of 1-2 mol/l at a temperature of 20-80°C., and the resulting nitrate solutions containing REE and impurity elements, is treated with a solution of formic acid with the release of formate REM in the form of sediment, cleansed from impurity elements, which include iron, aluminum, Nickel, cobalt, copper and other transition metals.

2. The method according to claim 1, characterized in that the anhydrous fluorides of rare-earth metals is carried out by oxidation of formate REM and solid state hydroperiodide at a temperature of 100°C, followed by drying and calcining to remove moisture.