JP2003113429A - Method for remelting scrap and/or sludge of rare earth magnet, alloy for magnet and rare earth sintered magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable all the components contained in scrap and/or sludge of a rare earth magnet to be simultaneously recycled, to improve separatability the slag occuring in from the molten metal, and to obtain a molten metal ingot at a high yield. SOLUTION: This method for remelting the scrap and/or the sludge of a R-Fe-B-based (R is a rare earth element including Y) rare earth magnet, includes charging a raw metal for magnet containing no rare earth element into a melting furnace crucible, heating and melting it, adding the scrap and/or the sludge of the R-Fe-B-based rare earth magnet to the melt together with a raw metal containing a rare earth element, of 0.1-50 wt.% with respect to the total raw metals, and furtheremore adding a flux with a mean diameter of 1-50 μm containing halides of a metal selected among an alkali metal, an alkaline earth metal, or a rare earth metal, of 0.01-30 wt.% with respect to the total raw metals, and melting them.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for remelting rare earth magnet scrap and / or sludge, and a rare earth alloy and a rare earth sintered magnet obtained by the method.

[0002]

2. Description of the Related Art Rare earth magnets are used in a wide range of fields from general home appliances to peripheral terminals for large computers and medical equipment, and are extremely important electronic devices that hold the key to advanced technology. It is one of the materials. In recent years, along with the reduction in size and weight of computers and communication devices, the demand for the rare earth magnets may rapidly increase due to the miniaturization and higher precision of the rare earth magnets and the future expansion of the usage.

Rare earth magnets are generally formed into a certain size, sintered, and then machined or ground to a predetermined size and shape, and then surface-treated such as plating or painting to obtain a product. Scraps such as molding leak powder, sintering / characteristic defective products, defective processing products, defective plating products, etc. generated in this process account for more than 10% of the original raw material weight, and sludge generated in the processing / grinding process ( Processing and grinding dust) can reach up to tens of percent of the raw material of the product. Therefore, recovery and reuse of rare earth elements from these rare earth magnet scraps and sludges save resources, reduce industrial waste,
Furthermore, it is an extremely important process for reducing the price of rare earth magnets.

In the manufacturing process of rare earth magnets, it is almost unavoidable to mix gas type impurities such as oxygen and carbon. Further, sludge consists of fine powder of magnet composition and rare earth oxides, but it is very active and easily oxidized, and since organic solvent mixed in the coolant used in the processing step adheres to the sludge surface, carbon, nitrogen,
The hydrogen concentration is hundreds to thousands times higher than that of normal alloy powder.

Generally, rare earth elements have an extremely high affinity with gas components such as oxygen and carbon, and it is difficult to remove these gas components. Therefore, it is very difficult to recover and reuse rare earth elements from rare earth magnet scrap and sludge.

Various methods have been proposed so far for regenerating rare earth magnet scrap or sludge.
Depending on the form of the rare earth element to be recovered or reused, it is classified into (1) rare earth recovery method, (2) alloy regeneration method, and (3) magnet regeneration method.

The rare earth recovery method is a method in which only rare earth elements are recovered from magnet scrap or sludge as a rare earth compound and recycled to a raw material step. After scrap is dissolved with an acid, the rare earth is fluoride or oxidized by a chemical treatment. It is a method of collecting rare earth metals by Ca reduction or electrolysis of molten salts. For example, a method of dissolving rare earth magnet scrap in a nitric acid-sulfuric acid aqueous solution, adding alcohol to the obtained solution to selectively crystallize the rare earth sulfate, and separating and recovering the rare earth element (Japanese Patent No. 2765470). A method of adding nitric acid to a slurry of a rare earth-iron alloy containing cobalt or cobalt, adding oxalic acid or a fluorine compound to the obtained solution containing cobalt and a rare earth, and separating and recovering the rare earth compound and cobalt (JP-A-9- No. 217132) and the like have been proposed. These methods have the advantage that a large amount of scrap or sludge can be treated at one time, and high-purity rare earth compounds can be recovered, but problems such as the use of a large amount of acid and the treatment of waste acid are difficult and the treatment process is complicated. There is.

The alloy recycling method is a method of recovering magnet scrap or sludge as an alloy having the same composition, and the scrap is melted by high frequency melting, arc melting, plasma melting or the like to obtain a magnet alloy. For example, a method of melting rare earth magnet scrap with a magnet raw material by high-frequency melting and regenerating as a magnet alloy (JP-A-8-31624) or a method of separating an alloy and slag by a zone melting method (JP-A-6-1).
Japanese Patent No. 36461) has been proposed. These methods can shorten the smelting process for obtaining alloys containing rare earths, the melting process for obtaining magnet alloys by recycling scraps as magnet alloys, and the expensive transitions other than rare earths contained in magnet scraps. Although it has a feature that metal can be reused, it has a problem that the recovery rate of rare earth elements is low, the crucible material is melted, and is mixed as a foreign matter into the ingot.

On the other hand, the magnet regeneration method is a method of regenerating scrap or sludge as a magnet. For example, magnet scrap is crushed, alloy powder rich in rare earths is mixed at a predetermined ratio, molded and sintered, Method for obtaining magnet (Patent No. 27)
No. 46818) has been proposed. This conventional method is a method of charging solid scrap and a rare earth alloy together in a crucible before heating and melting, and regenerating as a magnet alloy by melting in a high-frequency melting furnace. Since a magnet manufacturing apparatus can be used and expensive transition metals other than rare earths can be reused, there is a great economical advantage. Further, in order to prevent melting loss of the crucible material, about 10% by weight of the melting raw material is melted together, and flux is added to further reduce the amount of slag generated which causes melting loss of the crucible material. It is characterized by doing.

However, in this method, 90% of the melted raw material is used.
Since the scrap is scrap, the yield is very poor when flux is not added, the amount of flux added reaches 40% of the melting raw material, the melting loss of the crucible due to the flux, the magnetic characteristics due to mixing into the ingot, and the surface There arise problems such as deterioration of treatment characteristics, reduction of rare earth recovery rate, and increase of treatment cost.

Further, since 0.05 to 0.8% by weight of oxygen is inevitably mixed in the solid scrap in the magnet manufacturing process, when only the solid scrap is remelted in the high frequency melting furnace, the rare earth element is immediately added. It produces oxides and reduces the recovery rate of rare earths from solid scrap. Further, the generated rare earth oxide is widely dispersed in the molten metal and bonded in a network form, so that the molten metal stays between the oxide networks and deteriorates the separation between the molten metal and the slag.
Decrease ingot recovery yield.

[0012] Generally, when a low-quality melting raw material such as scrap is melted, a large amount of slag is generated. Further, the separability between the generated slag and the molten metal is very poor, and sound molten metal is caught in the slag and remains in the crucible, and the recovery yield of the obtained molten ingot is low. Therefore, some methods have been proposed to solve the above problems.

For example, as a method for producing a high-purity rare earth metal, the rare earth metal and its fluoride are heated and melted together,
A method of defluorinating by removing oxygen and then remelting in high vacuum has been proposed.However, since a large amount of rare earth fluoride is added, crucibles such as tantalum are used to prevent melting damage of the crucible. Must be used. In addition, it is necessary to perform a re-dissolution process in order to remove fluorine mixed as impurities.

Further, in the method of preparing the magnet alloy by previously charging the magnet scrap and the rare earth alloy together in a crucible in advance, melting them by heating, and then adding the flux and the scrap, the amount of flux to be added is melted. Since it reaches as much as 40% of the raw material, undissolved flux may remain and be caught in the ingot. Further, there is a problem in that the magnetic flux and surface treatment properties of the obtained magnet are adversely affected by the fact that the flux scatters during vacuum evacuation and flux addition and mixes into the ingot.

Therefore, the present invention uses the rare earth magnet scrap and / or sludge as a melting raw material to remelt the rare earth magnet scrap and / or sludge capable of recovering the rare earth element with high efficiency and with an improved melting yield. It is an object of the present invention to provide a method, a rare earth alloy obtained by this method, and a rare earth sintered magnet.

Further, the present invention is a rare earth magnet scrap capable of obtaining a high-purity magnet alloy using rare earth magnet scrap and / or sludge as a melting raw material by suppressing the scattering of flux and suppressing the pollution in the melting furnace. Another object is to provide a method of remelting sludge and / or a rare earth alloy and a rare earth sintered magnet obtained by this method.

[0017]

Means for Solving the Problems and Embodiments of the Invention As a result of intensive studies to achieve the above object, the present inventors have found that R-Fe-B rare earth magnet scrap and / or sludge (R: Rare earth elements including Y, preferably Pr, N
When redissolving one or more kinds of rare earth elements selected from d, Tb and Dy, R-F containing no rare earth element in advance
A raw material metal used for an e-B magnet is charged into a crucible, heated and melted, and a raw material metal containing a rare earth element, an R-Fe-B rare earth magnet scrap and / or sludge, and an alkali metal, an alkaline earth metal, or a rare earth metal. It has been found that by adding an appropriate amount of a flux containing a halide of one kind or two or more kinds of metals selected from metals, it is possible to recover rare earth elements with high efficiency and also improve the melting yield.

Further, the present inventors, when remelting rare earth magnet scrap and / or sludge, include a halide of one or more metals selected from alkali metals, alkaline earth metals and rare earth metals. Average particle size is 1
A flux of 50 μm is wrapped with a metal composed of a rare earth magnet constituent element, and this is added to the molten metal containing the rare earth magnet scrap and / or sludge, thereby suppressing the scattering of the flux and suppressing the contamination in the melting furnace, The inventors have found that a high-purity alloy for magnet materials can be produced, and have completed the present invention.

That is, according to the present invention, (1) R-Fe-B system (R is a rare earth element containing Y, preferably Pr, Nd, T).
b, showing one or more rare earth elements selected from Dy) Re-melting method for reusing scrap and / or sludge of a rare earth magnet as a melting raw material,
First, a magnet raw material metal containing no rare earth is charged into a melting furnace crucible, heated and melted, and then the raw material metal containing rare earth is added to the melt together with the R-Fe-B rare earth magnet scrap and / or
Alternatively, 0.1 to 50% by weight of the raw metal is added to the sludge,
Further, 0.01 to 30% by weight of the raw material metal is added with a flux containing a halide of one or more metals selected from alkali metals, alkaline earth metals and rare earth metals, and the flux is dissolved. -Fe-B rare earth magnet scrap and / or sludge remelting method, and (2)
In a remelting method for reusing scrap and / or sludge of R-Fe-B system (R represents a rare earth element containing Y) as a melting raw material, alkali metal, alkaline earth metal or rare earth metal is used. Average particle size of 1 to 2 selected from halides of metals
R-F, characterized in that a flux of 50 μm is wrapped with a metal composed of a rare earth magnet constituent element and added to a molten metal containing the rare earth magnet scrap and / or sludge.
Re-melting method for e-B rare earth magnet scrap and / or sludge, (3) charging magnet raw metal not containing rare earth into a melting furnace crucible, heating and melting, and then melting the raw metal together with raw metal containing rare earth R-Fe-B rare earth magnet scrap and / or sludge is added in an amount of 0.1 to 50% by weight of the raw material, and halogen of one or more metals selected from alkali metals, alkaline earth metals and rare earth metals is further added. 0.01 to 30 of the raw material metal by wrapping a flux containing an oxide with an average particle diameter of 1 to 50 μm with a metal composed of a rare earth magnet constituent element.
(2) The method of re-dissolving R-Fe-B rare earth magnet scrap and / or sludge, wherein the metal is Al, Cu, Fe.
A method for remelting R-Fe-B rare earth magnet scrap and / or sludge according to (2) or (3), which is at least one metal selected from the group consisting of:
A rare earth alloy characterized by being obtained by the above method,
(6) A rare earth sintered magnet using the above rare earth alloy is provided.

The present invention will be described in more detail below.
In the rare earth magnet scrap and / or sludge remelting method of the present invention, R-Fe-B rare earth magnets are used as the rare earth magnets, and these scraps and sludges (hereinafter, these are referred to as solid scraps) include: Scraps such as molding leakage powder, sintering / defective product, defective product, defective plating product, etc. generated in the rare earth sintered magnet manufacturing process, and sludge (processing / grinding dust) generated in the processing / grinding process are used. , Mainly R-T-B composition (R is a rare earth element containing Y, preferably at least one rare earth element selected from Pr, Nd, Tb and Dy, and T is Fe.
Alternatively, it contains Fe and at least one other transition metal phase. The composition of the scrap is close to that of the molten ingot, but oxygen, carbon, and nitrogen, which are inevitably mixed in the magnet manufacturing process, are usually 0.05 to 0.8% by weight, 0.03 to 0.1% by weight, and 0, respectively. 0.002 to 0.02% by weight.

In the first aspect of the present invention, when the solid scrap is remelted to obtain an R-Fe-B based magnet alloy, a magnet raw material containing no rare earth so that the magnet alloy has a desired composition. A metal, a raw material metal containing a rare earth, and the above solid scrap are prepared. First, a metal not containing a rare earth is melted in advance in a melting furnace crucible, and a metal containing a rare earth and a solid scrap are further added to and melted in the melt. In addition, as the metal containing no rare earth, electrolytic iron, ferroboron, Co, Al and the like can be mentioned, and the composition may be adjusted so as to obtain a desired alloy. Examples of the metal containing a rare earth include Nd, Dy, Nd-Fe, Dy-Fe and the like.

Also in the second aspect of the present invention, the order of melting these melting raw materials is appropriately selected, but it is preferable to use 15 magnet raw metal containing no rare earth.
It is melted at a temperature of 00 ° C. or higher, and a raw material metal containing rare earth and solid scrap are added and melted in this melt.

In this case, in the present invention, the above solid
Add flux to the scrap-added melt.
As a flux, a halide consisting of magnet constituent elements
Is preferred, but alkali metal, alkaline earth metal, rare earth
One or more halides of group metals may be used. Ha
Examples of the rogen include chlorine, fluorine, bromine and iodine.
Among them, it is preferable to use fluoride. For example, Nd
F₃, PrF₃, DyF ₃, TbF₃, MgF₂, CaF₂,
BaF₂, LiF, NaF, KF, NdCl₃, PrCl
₃, DyCl₃, TbCl₃, MgCl₂, CaCl₂, B
aCl₂, LiCl, NaCl, KCl, NdBr₃, P
rBr₃, DyBr₃, TbBr₃, NdI ₃, PrI₃,
DyI₃, TbI₃Such as halides and the above
Two or more mixed halides are used.

The amount of the above-mentioned flux added is 0.01 to 30% by weight of the total raw material metal (that is, the sum of the raw material metal containing no rare earth and the raw material metal containing rare earth), and particularly 0.05 to 10% by weight. Weight percent is preferred. Addition amount is 0.0
When it is less than 1% by weight, no remarkable effect is observed.
When the added amount exceeds 30% by weight, the added flux reacts with the crucible material and melts the inner wall of the crucible. Further, if the added flux is mixed in the ingot, it adversely affects the magnetic characteristics and surface treatment characteristics of the sintered magnet.

Here, in order to suppress the evaporation loss due to the transfer of the rare earth element to the slag phase and the dissolution by heating,
The solid scrap is a magnet raw material metal containing no rare earth in an inert gas at 1500 ° C. or higher, preferably 1500 to 180.
It is preferable that after heating and melting at 0 ° C., it is added together with the raw material metal containing the rare earth and the flux, and further melted at 1500 ° C. or higher, preferably 1500 to 1800 ° C. Especially, dysprosium, which is a scarce resource among rare earth elements and is expensive, forms a stable oxide and is easily transferred to the slag phase, and further has a high vapor pressure, so that loss during heating and melting is large. Therefore, it is possible to suppress the loss of rare earth elements in the scrap by adding the solid scrap together with the rare earth-containing raw material metal later.

The solid scrap is preferably added in an amount of 0.1 to 50% by weight, and more preferably 0.5 to 30% by weight, of the total raw material metal together with the rare earth-containing raw material metal and the flux. If the scrap input exceeds 50% by weight, the yield of the obtained ingot deteriorates, which is not preferable.

In this case, the present invention adds the flux to the molten metal containing solid scrap, but the second invention of the present invention is characterized by the method of adding the flux,
The flux is to be added to the molten metal by wrapping it with a metal composed of a magnet-constituting element such as Al, Fe and Cu, preferably a metal foil. If metal is not used, powdery flux may scatter and contaminate the furnace and the ingot. When wrapped with a metal other than the magnet constituent elements, it is mixed as an impurity in the alloy and the alloy composition is not stable. Furthermore, it is not preferable because it adversely affects the magnetic properties of the magnet obtained from the alloy. The thickness of the metal foil is not particularly limited, but a metal foil having a thickness of 0.1 to 100 μm can be used.

The flux to be added is, as described above,
Using a halide of one or more metals selected from alkali metals, alkaline earth metals and rare earth metals,
This is preferably added in an amount of 0.01 to 30% by weight, more preferably 0.05 to 10% by weight, based on the total amount of the dissolved material. Particularly, rare earth halides and further fluorides are preferable.

The average particle size of the added flux is 1 to 5
The particle size is 0 μm, preferably 5 to 20 μm, and the shape is preferably powder. Average particle size of flux is 1 μm
If it is less than the above range, it scatters during the vacuum evacuation of the furnace and the addition of the flux, and the inside of the furnace and the ingot are contaminated. If the average particle size of the flux is larger than 50 μm,
It is not preferable because the added flux does not completely melt and the molten metal entrains the unmelted flux adhered to the inner wall of the crucible. The flux mixed in the ingot as an impurity is not preferable because it adversely affects the magnetic characteristics and the surface treatment characteristics.

In the second invention, a rare earth element as an alloy raw material,
Electrolytic iron, Co, each element, etc. 1500 in inert atmosphere
High-frequency melting at ℃ or more, preferably 1500 to 1800 ℃, while adding the desired amount of rare earth magnet scrap and / or sludge while maintaining the molten state, at the same time, a metal-encapsulated flux having an average particle size of 1 to 50 μm Is further added to the molten metal at 1500 ° C. or higher, preferably 15
It is preferable to adopt a method of producing an alloy by heating and melting at 00 to 1800 ° C. and casting in a mold or the like. By this method, it is possible to prevent the flux from being scattered during melting and prevent fluorine from being mixed into the alloy.

The alloy composition obtained in the present invention is an alloy for rare earth magnets, and in particular, an R ₂ Fe ₁₄ B based magnet alloy is preferable, in which R is a rare earth element containing Y,
Preferably, the alloy contains 27 to 33 wt% as one or more rare earth elements selected from Pr, Nd, Tb, and Dy, and the balance is Fe or Fe and a transition metal other than Fe (Co, Cu, Al). , Ti, Si, V, Mn, Ni, N
b, Zr, Ta, Cr, Mo, Hf), and an R ₂ Fe ₁₄ B-based alloy composition containing 6% by weight or less of B is preferable. Therefore, when obtaining such an alloy composition, the metal that wraps the flux may be any metal selected from the above alloy compositions, and the form is preferably a metal foil. Specifically, it is preferable to use one or more metals selected from Al, Fe, Cu or alloys thereof.

The alloy obtained in the present invention is mechanically pulverized by a usual method such as a brown mill, and finely pulverized by an inert gas such as nitrogen or argon gas so that the average particle diameter becomes 3 to 10 μm (especially jet mill etc.). Then, a rare earth sintered magnet can be obtained by magnetic field forming, sintering at 1000 to 1200 ° C. in a vacuum or an inert atmosphere, and optionally aging at 400 to 600 ° C. in a vacuum or an inert atmosphere.

[0033]

EXAMPLES The present invention will be specifically described below by showing Examples and Comparative Examples, but the present invention is not limited to the following Examples. In the following examples,% means% by weight unless otherwise specified.

[Example 1] Nd and D were used as starting materials.
y, electrolytic iron, Co, ferroboron, Al and rare earth magnet scrap (30Nd-3Dy-BAL.Fe-3.5
Co-1.1B-0.2Al) was used. The weight ratio (%) of these raw materials was 26Nd-1.5Dy-BAL.
The raw materials were adjusted so that the composition was Fe-1Co-1.1B-0.2Al.

First, electrolytic iron, Co, ferroboron,
Charge Al raw material into the crucible of the high frequency melting furnace and put it in Ar atmosphere.
It was melted in by high frequency induction heating. Then melt meta
After confirming that the temperature of the battery has reached 1500 ° C or higher,
5% rare earth magnet scrap with d, Dy raw metal
Was added. At the same time, 10% NdF as flux ₃
(Average particle size 5 μm) was added. Leave for a few minutes after addition
Then, it was confirmed that the temperature of the molten metal became 1500 ° C or higher.
After that, the molten metal was cast into a copper mold to obtain a magnet alloy.
Table 1 shows the results of dissolution. The dissolution yield was 99.1%
It was The composition of the obtained ingot is almost the same as the raw material composition.
However, the fluorine concentration was 100 ppm or less.
It was

[0036]

[Table 1]

The ingot was roughly pulverized and then finely pulverized with a jet mill in a nitrogen stream to obtain fine powder having an average particle size of about 3 μm. Then, these fine powders were filled in a mold of a molding apparatus, oriented in a magnetic field of 12 kOe, and press-molded in a direction perpendicular to the magnetic field at a pressure of 1 ton / cm ² . The obtained molded body was sintered at 1100 ° C. for 2 hours in an Ar atmosphere, cooled, and then heat-treated at 500 ° C. for 1 hour in an Ar atmosphere to produce a permanent magnet material. When the magnetic properties of the obtained sintered magnet were measured, it showed properties equivalent to those of a sintered magnet of the same composition to which rare earth magnet scrap was not added (Table 2). Further, when the obtained sintered magnet was formed into a desired shape and cut, and then plated with Ni and subjected to a corrosion resistance test, there was no significant influence on its characteristics.

[0038]

[Table 2]

[Comparative Example 1] Nd and D were used as starting materials.
y, electrolytic iron, Co, ferroboron, Al and rare earth magnet scrap (30Nd-3Dy-BAL.Fe-3.5
Co-1.1B-0.2Al) was used. The weight ratio (%) of these raw materials was 26Nd-1.5Dy-BAL.
The raw materials were adjusted so that the composition was Fe-1Co-1.1B-0.2Al.

First, electrolytic iron, Co, ferroboron,
The Al raw material was placed in a high-frequency melting furnace crucible and melted by high-frequency induction heating in an Ar atmosphere. After confirming that the temperature of the molten metal has reached 1500 ° C or higher, N
25% rare earth magnet scrap was added together with d and Dy raw material metals. After the addition, let stand for a few minutes until the temperature of the melt is 15
After confirming that the temperature became 00 ° C. or higher, the molten metal was cast into a copper mold to obtain a magnet alloy. The ingot recovery yield was 86.5%.

Comparative Example 2 Nd and D were used as starting materials.
y, electrolytic iron, Co, ferroboron, Al and rare earth magnet scrap (30Nd-3Dy-BAL.Fe-3.5
Co-1.1B-0.2Al) was used. The weight ratio (%) of these raw materials was 26Nd-1.5Dy-BAL.
The raw materials were adjusted so that the composition was Fe-1Co-1.1B-0.2Al.

First, electrolytic iron, Co, ferroboron,
An Al raw material and 5% rare earth magnet scrap were placed in a high-frequency melting furnace crucible and were melted by high-frequency induction heating in an Ar atmosphere. After that, the temperature of the molten metal is 1500 ° C
After confirming the above, Nd and Dy raw material metals were added. At the same time, 10% NdF as flux
₃ (average particle size 5 μm) was added. After the addition, the mixture was allowed to stand for several minutes, and after confirming that the temperature of the molten metal reached 1500 ° C. or higher, the molten metal was cast into a copper mold to obtain a magnet alloy.
The dissolution results are shown in Table 3. The dissolution yield was 98.5%. The composition of the ingot obtained is Dy
The concentration was about 0.2% lower. Fluorine concentration is 10
It was 0 ppm or less.

[0043]

[Table 3]

Comparative Example 3 Nd and D were used as starting materials.
y, electrolytic iron, Co, ferroboron, Al and rare earth magnet scrap (30Nd-3Dy-BAL.Fe-3.5
Co-1.1B-0.2Al) was used. The weight ratio (%) of these raw materials was 26Nd-1.5Dy-BAL.
The raw materials were adjusted so that the composition was Fe-1Co-1.1B-0.2Al.

First, electrolytic iron, Co, ferroboron,
Charge Al raw material into the crucible of the high frequency melting furnace and put it in Ar atmosphere.
It was melted in by high frequency induction heating. Then melt meta
After confirming that the temperature of the battery has reached 1500 ° C or higher,
5% rare earth magnet scrap with d, Dy raw metal
Was added. At the same time, 40% NdF as flux ₃
(Average particle size 5 μm) was added. Leave for a few minutes after addition
Then, it was confirmed that the temperature of the molten metal became 1500 ° C or higher.
After that, the molten metal was cast into a copper mold to obtain a magnet alloy.
The dissolution results are shown in Table 4. The dissolution yield was 99.0%.
It was The composition of the obtained ingot is almost the same as the raw material composition.
However, the fluorine concentration was 5320 ppm.
It was

[0046]

[Table 4]

The ingot was roughly pulverized and then finely pulverized by a jet mill in a nitrogen stream to obtain fine powder having an average particle size of about 3 μm. Then, these fine powders were filled in a mold of a molding apparatus, oriented in a magnetic field of 12 kOe, and press-molded in a direction perpendicular to the magnetic field at a pressure of 1 ton / cm ² . The obtained molded body was sintered at 1100 ° C. for 2 hours in an Ar atmosphere, cooled, and then heat-treated at 500 ° C. for 1 hour in an Ar atmosphere to produce a permanent magnet material. When the magnetic properties of the obtained sintered magnet were measured, both the residual magnetic flux density and the coercive force were lower than those of the sintered magnet of the same composition to which rare earth magnet scrap was not added (Table 5). Furthermore, after shaping and cutting the obtained sintered magnet into the desired shape, Ni plating was performed and a corrosion resistance test was performed, and it was found that there was more rust than in the sintered magnet of the same composition to which rare earth magnet scrap was not added. Occurred.

[0048]

[Table 5]

[Example 2] Nd and D were used as starting materials.
y, electrolytic iron, Co, ferroboron, Al and rare earth magnet scrap (30Nd-3Dy-BAL.Fe-3.5
Co-1.1B-0.2Al) was used. The weight ratio (%) of these raw materials was 26Nd-1.5Dy-BAL.
The raw materials were adjusted so that the composition was Fe-1Co-1.1B-0.2Al.

First, electrolytic iron, Co and ferroboron were placed in a high frequency melting furnace crucible (made of alumina) and melted by high frequency induction heating in an Ar atmosphere. After confirming that the temperature of the molten metal reached 1500 ° C. or higher, 5% rare earth magnet scrap was added together with the Nd and Dy raw material metals. At the same time, 10% of NdF ₃ powder having an average particle size of 5 μm was wrapped as an flux in an Al foil (thickness 15 μm) and added. After the addition, the mixture was allowed to stand for several minutes, and after confirming that the temperature of the molten metal reached 1500 ° C. or higher, the molten metal was cast into a copper mold to obtain a magnet alloy. Table 6 shows the dissolution results. The composition of the obtained ingot was almost the same as the composition of raw materials, and the inclusion of flux as an impurity was not confirmed. Further, melting damage on the inner wall of the crucible was not confirmed.

[0051]

[Table 6]

The ingot was roughly pulverized and then finely pulverized with a jet mill in a nitrogen stream to obtain fine powder having an average particle size of about 3 μm. Then, these fine powders were filled in a mold of a molding apparatus, oriented in a magnetic field of 12 kOe, and press-molded in a direction perpendicular to the magnetic field at a pressure of 1 ton / cm ² . The obtained molded body was sintered at 1100 ° C. for 2 hours in an Ar atmosphere, cooled, and then heat-treated at 500 ° C. for 1 hour in an Ar atmosphere to produce a permanent magnet material. As a result, good magnetic properties were obtained (Table 7). Further, when the obtained sintered magnet was shaped and cut into a desired shape, Ni plating was performed, and a corrosion resistance test was performed, the characteristics were not significantly affected.

[0053]

[Table 7]

[Comparative Example 4] Nd and D were used as starting materials.
y, electrolytic iron, Co, ferroboron, Al and rare earth magnet scrap (30Nd-3Dy-BAL.Fe-3.5
Co-1.1B-0.2Al) was used. The weight ratio (%) of these raw materials was 26Nd-1.5Dy-BAL.
The raw materials were adjusted so that the composition was Fe-1Co-1.1B-0.2Al.

First, electrolytic iron, Co, and ferroboron were placed in a high-frequency melting furnace crucible (made of alumina) and melted by high-frequency induction heating in an Ar atmosphere. After confirming that the temperature of the molten metal reached 1500 ° C. or higher, 5% rare earth magnet scrap was added together with the Nd and Dy raw material metals. At the same time, 10% of NdF ₃ powder having an average particle size of 0.5 μm was wrapped as Al flux and added as a flux. After the addition, the mixture was allowed to stand for several minutes, and after confirming that the temperature of the molten metal reached 1500 ° C. or higher, the molten metal was cast into a copper mold to obtain a magnet alloy. Table 8 shows the dissolution record. The dissolution yield was 95.2%. There was no significant change in the impurity fluorine concentration. Further, NdF ₃ powder was scattered in the furnace after melting and adhered to the furnace wall.

[0056]

[Table 8]

[Comparative Example 5] Nd and D were used as starting materials.
y, electrolytic iron, Co, ferroboron, Al and rare earth magnet scrap (30Nd-3Dy-BAL.Fe-3.5
Co-1.1B-0.2Al) was used. The weight ratio (%) of these raw materials was 26Nd-1.5Dy-BAL.
The raw materials were adjusted so that the composition was Fe-1Co-1.1B-0.2Al.

First, electrolytic iron, Co, ferroboron,
The Al raw material was charged into a high-frequency melting furnace crucible (made of alumina) and melted by high-frequency induction heating in an Ar atmosphere. After confirming that the temperature of the molten metal reached 1500 ° C. or higher, 5% rare earth magnet scrap was added together with the Nd and Dy raw material metals. At the same time, 10% of NdF ₃ powder having an average particle diameter of 500 μm was wrapped as Al flux and added as a flux. After the addition, let stand for a few minutes until the temperature of the melt is 15
After confirming that the temperature became 00 ° C. or higher, the molten metal was cast into a copper mold to obtain a magnet alloy. Table 9 shows the dissolution results. The dissolution yield was 98.5%. The impurity fluorine concentration was 350 ppm. Further, after melting, undissolved NdF ₃ was segregated on the inner wall of the crucible. In addition, the inner wall of the crucible after dissolution was damaged by the reaction with the fluoride.

Using the ingot, a permanent magnet material was produced in the same manner as in Example 2. When the magnetic characteristics of the obtained magnet were measured, the coercive force was reduced by 500 Oe. Further, after shaping and cutting the sintered magnet into a desired shape, Ni plating was applied thereto, and a corrosion resistance test was conducted. As a result, a large amount of red rust was generated from pinholes.

[0060]

[Table 9]

[0061]

According to the first aspect of the present invention, all the elements contained in the rare earth magnet scrap and / or sludge can be recycled at the same time, and further, the separability between the slag and the molten metal generated during melting can be improved. It makes it possible to improve and obtain a molten ingot with a high yield. Further, the process is simple as compared with the conventional treatment method, and the treatment is economically possible, so that its utility value is extremely high in industry.
According to the second aspect of the present invention, in remelting rare earth magnet scrap and / or sludge, when adding a flux essential for improving the recovery yield thereof,
Reduces contamination of the furnace and ingots with flux,
High quality alloys for magnetic materials can be manufactured.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01F 41/00 H01F 41/02 G 41/02 1/04 HF term (reference) 4K001 AA10 AA39 AA42 BA14 BA15 BA22 FA14 GA17 KA08 KA09 KA13 5E040 AA04 CA01 HB11 NN17 5E062 CD04 CE01 CG01

Claims (9)

[Claims] 1. A remelting method for reusing scrap and / or sludge of an R—Fe—B system (R represents a rare earth element containing Y) rare earth magnet as a melting raw material. The raw material metal is charged into a melting furnace crucible, heated and melted, and then the R-Fe-B rare earth magnet scrap and / or sludge together with the raw material metal containing rare earth in the melt is added in an amount of 0.1 to 50 weight of the raw material metal %, And a flux having an average particle size of 1 to 50 μm containing a halide of one or more metals selected from alkali metals, alkaline earth metals and rare earth metals is added in an amount of 0.01 to 30% by weight of the raw material metal. A method for remelting R-Fe-B rare earth magnet scrap and / or sludge, which comprises adding and melting. 2. The R-Fe-B rare earth magnet scrap and / or sludge according to claim 1, wherein R is at least one rare earth element selected from Pr, Nd, Tb and Dy. Redissolution method. 3. An R—Fe—B based rare earth alloy obtained by the method according to claim 1. 4. An R—Fe—B based rare earth sintered magnet using the rare earth alloy according to claim 3. 5. A remelting method for reusing scrap and / or sludge of an R—Fe—B system (R represents a rare earth element containing Y) rare earth magnet as a melting raw material, wherein an alkali metal or alkaline earth metal is used. A flux having an average particle size of 1 to 50 μm containing a halide of one or more metals selected from metals and rare earth metals is wrapped with a metal composed of a rare earth magnet constituent element, and melting containing the rare earth magnet scrap and / or sludge. A method for remelting R-Fe-B rare earth magnet scrap and / or sludge, which is characterized by being added to a metal. 6. A magnet raw material metal containing no rare earth is charged into a melting furnace crucible and heated and melted, and then R—Fe—B rare earth magnet scrap and / or sludge is added to the melt together with the raw material metal containing rare earth. The rare earth magnet is added with 0.1 to 50% by weight of the raw material, and a flux having an average particle diameter of 1 to 50 μm containing a halide of one or more metals selected from alkali metals, alkaline earth metals and rare earth metals. 0.01 to 30 of the raw material metal wrapped with a metal composed of constituent elements
The method for re-dissolving R-Fe-B rare earth magnet scrap and / or sludge according to claim 5, characterized in that it is added by weight% and dissolved. 7. The R-Fe-B rare earth magnet scrap and / or sludge according to claim 5, wherein the metal is at least one metal selected from Al, Cu and Fe. Redissolution method. 8. An R—Fe—B-based rare earth alloy obtained by the method according to claim 5, 6, or 7. 9. An R—Fe—B based rare earth sintered magnet using the rare earth alloy according to claim 8.