WO2003076691A1

WO2003076691A1 - Process for producing r-iron alloy

Info

Publication number: WO2003076691A1
Application number: PCT/JP2003/002906
Authority: WO
Inventors: Yasuhiro Yamamoto; Yukihiro Yokoyama; Akihito Kaneko
Original assignee: Santoku Corporation
Priority date: 2002-03-13
Filing date: 2003-03-12
Publication date: 2003-09-18
Also published as: CN1643184A; AU2003221351A1; JP4284191B2; CN100402706C; JPWO2003076691A1

Abstract

A process for continuously producing a high-grade R-Fe alloy stably for a prolonged period of time while, at charging level, suppressing the variation of composition of obtained alloy and suppressing the content of impurities. The process comprises step (A) of providing an electrolytic apparatus including an electrolytic furnace equipped with a direct current electrode and heating means for heating a furnace bottom surface; step (B) of introducing a direct current electrode and a specified fluoride melt electrolytic bath in the electrolytic furnace; step (C) of performing electrolytic reduction of DyF3 and/or TeF3 as a raw material in order to form an R-Fe alloy and deposit the alloy on a bottom portion of the electrolytic furnace; and step (D) of recovering the alloy deposited in the step (C). The electrolytic reduction of the step (C) is performed while effecting heat control by the heating means so as to maintain the temperature of the deposited alloy at 850-1000ºC under such conditions that the temperature of electrolytic bath between the direct current electrodes is maintained at 900-970ºC.

Description

Specification

R—Method of manufacturing iron alloy

Technical field

The present invention uses an electrolysis apparatus including an iron cathode, a graphite anode, and an electrolysis furnace to electrolytically reduce a disposable compound and a Z or terbium compound in a fluoride molten electrolytic bath. Regarding the production of R-iron alloys such as Dysprosium-iron alloys, terbium-iron alloys, and Dysprosium-terbium-iron alloys, high-quality R-iron, which is particularly suitable as an additive to rare-earth iron-based alloys for magnet applications The present invention relates to a method for producing an alloy.

Background art

In recent years, demand for dysprosium and terbium has been increasing as an additive material for enhancing the coercive force of rare-earth iron-based magnets. Dysprosium is usually produced as a simple metal or an alloy with iron by reducing disodium fluoride with calcium metal. However, the production by the calcium reduction method is expensive because it is performed by a patch treatment, and the obtained metal or alloy contains many impurities such as calcium and oxygen, so that a complicated purification step is required.

On the other hand, Japanese Patent Publication No. 5-61357 discloses a method of electrolytically manufacturing a ferrous alloy that can be continuously manufactured, using a consumable electrode type electrolytic furnace using an iron cathode and a graphite anode, and using a fluoride fluoride system. , A mixed electrolytic bath of lithium, barium fluoride, calcium fluoride, etc. is maintained in a temperature range of 870 to L000 ° C, and the anode current density is 0.05 to 4 A / cm ² _N cathode current density A method for producing a disposable ferrous alloy having a disposable content of 80% or more by setting the temperature to 0.5 to 80 AZcm ² is disclosed.

However, with this method, it is possible to continuously produce the iron alloy of Dysprosium for a certain period of time, but it is not possible to stably and efficiently produce the alloy composition over a long period of time. By the way, at the conventional actual operation level in which an electrolytic device having a DC electrode composed of an iron cathode and a black bell anode is used to electrolytically reduce a dysprosium compound in a molten fluoride electrolytic bath, the generation occurs between the electrodes. It is recognized that the temperature of the electrolytic bath itself can be kept substantially constant by Joule heat. For this reason, the temperature control of the electrolytic bath is usually mainly performed by the above-mentioned Joule heat, and the control of the temperature of the obtained alloy other than the temperature of the electrolytic bath is generally not performed. Not considered.

In addition, terbium iron alloy disposable terbium iron alloy, terbium fluoride There is no known method for producing a raw material using a rubber.

Disclosure of the invention

An object of the present invention is to provide a high-quality disposable iron-iron alloy, a terbium-iron alloy, and a disposable iron-terbium-iron alloy in which the composition variation of the obtained alloy is suppressed at the mounting level and the content of impurities such as carbon is suppressed. The aim is to develop a method for producing an R-iron alloy that can be obtained continuously for a long period of time.

The present inventors have conducted intensive studies to solve the above problems. First, in order to find out why it is not possible to obtain a disposable iron-iron alloy with a stable composition for a long time at the conventional mounting level, the electrolytic raw material, the raw material supply method, the electrode configuration, the electrolytic The relationship between the bath composition, electrode potential, operating temperature, etc., and the operating stability and composition of the formed alloy was studied diligently. As a result, in general, dino ^, which heats the electrolytic bath with heat, is generated between the electrodes.In the method where the anode and cathode are inserted from above the electrolytic furnace, the heat generation site is biased toward the electrolytic bath. It was found that the temperature was high near the electrode where Joule heat was applied, and the temperature of the electrolytic bath below the electrolytic furnace where the deposited alloy was stored was lower than that near the electrode. This tendency was the same even when the operation of keeping the temperature of the electrolytic bath uniform was performed, except that the temperature difference was different.

Normally, in the production of R-iron alloys composed of ferrous iron, terbium iron alloy, and disproportionate iron alloy by electrolysis using an iron cathode as a consumable electrode, the melting point of the dysprosium is 1407. ° C, terbium has a melting point of 1356 ° C, which is higher than the normal operating temperature, so that dysprosium and terbium reduced on the iron cathode surface immediately form an alloy with iron. The alloy formed in the early stage of electrolysis exists in a solid state on the cathode surface because of its low melting point and high content of dysprosium and terbium. As the reduction reaction proceeds, the dysprosium / terbium content of the resulting alloy increases, and the melting point of the resulting R-iron alloy also decreases. When the temperature of the electrode and the melting point of R-gold become equal, the R-iron alloy melts and settles to the bottom of the furnace due to the difference in specific gravity with the electrolytic bath. As described above, since the electrode temperature determines the composition of the R-iron alloy, it is important to maintain a constant ^^ of the electrolytic bath between the electrodes in order to produce a stable composition of the R-iron alloy.

On the other hand, the R-iron alloy that melts and settles to the bottom of the electrolytic furnace is at a temperature just above the melting point. If the temperature of the bottom of the electrolytic furnace is lower than the temperature near the electrode, in extreme cases, the solidification point may occur during the settling. And solidifies in a form involving the electrolytic bath, forming a gel-like precipitate. Such precipitates accumulate at the interface between the precipitated alloy and the electrolytic bath. Therefore, the Joule heat generated in the upper part of the electrolytic bath is blocked by the deposited sediment, and the temperature difference between the precipitated alloy and the electrolytic bath is further increased, thereby increasing the amount of the sediment. In addition, since the specific gravity of the precipitate is very close to that of the alloy, when the alloy is taken out, the separability from the alloy is poor, and the yield of the alloy is poor.

Furthermore, when no precipitate is generated, that is, when the temperature of the entire electrolytic bath is kept as uniform as possible by ordinary temperature control of the electrolytic bath to make the alloy that precipitates at the bottom of the electrolytic furnace liquid. However, it was found that a large amount of impurity components were contained in the alloy, and a phenomenon that hindered long-term operation occurred.

The reason why this phenomenon occurs is not clear, but even at the age of performing an operation to keep the temperature of the electrolytic bath as uniform as possible, the temperature of the alloy that precipitates at the bottom of the electrolytic furnace is lower than that of the electrolytic bath. It was found that the temperature was often lower, and in long-term operation, it could be 100 ° C or more lower than the electrolytic bath. Then, it was found that even when the alloy was in a liquid state, the probability of occurrence of the above-described phenomenon was high even when the temperature of the agitated alloy was lowered to some extent. Assuming the reason, when the alloy formed by electrolytic reduction at the cathode is precipitated at the bottom of the electrolytic furnace, the alloy always falls while winding the electrolytic bath. At this time, if the temperature of the liquid alloy that has already been precipitated is somewhat high, the wound electrolytic bath is separated at the interface between the electrolytic bath and the alloy. It is considered that the probability that a strong separation does not occur increases. Such a tendency is particularly likely to occur in long-term continuous operation.

Therefore, based on the above assumption, an attempt was made in a specific range to control the temperature of the precipitated alloy, which has not been conventionally performed. As a result, it was found that long-term stabilization of electrolytic operation can be achieved by controlling the temperature of the precipitated alloy. Furthermore, by controlling both the temperature of the electrolytic bath between the DC electrodes during electrolytic reduction and the temperature of the precipitated alloy so as to control the difference between these temperatures to be within a specific temperature range, the electrolytic operation can be further improved. It was found that long-term stability could be achieved.

That is, according to the present invention, there is provided an electrolysis apparatus including a direct current electrode including a cathode made of iron and an anode made of black bell, and an electrolysis furnace having at least heating means for heating the bottom of the furnace. Step (A), the electrolytic furnace is provided with the DC electrode, at least one rare earth fluoride of disperse fluoride and terbium fluoride, lithium fluoride and lithium fluoride. (B) introducing a fluoride molten electrolytic bath, and forming an R-iron alloy (R indicates disprosium, terbium or dysprosium terbium), and depositing the alloy at the bottom of the electrolytic furnace (C) electrolytically reducing at least one of dispersium fluoride and terbium fluoride as raw materials, and (D) recovering the R-iron alloy precipitated by step (C), The electrolytic reduction in the step (C) is performed under the condition that the temperature of the electrolytic bath between the DC electrodes is maintained at 900 to 970 ° C, and the temperature of the precipitated alloy is adjusted to 850 to 850 by the heating means provided in the electrolytic furnace. ; Heating is controlled within the range of 1000 ° C.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic diagram showing an electrolysis apparatus used in Examples and Comparative Examples.

Preferred embodiments of the invention

Hereinafter, the present invention will be described in more detail.

The present invention uses an electrolytic apparatus equipped with a specific electrolytic furnace, and uses at least one of a fluoride dysprosium and terbium fluoride as a raw material in a fluoride molten electrolytic bath, and determines the temperature of the electrolytic bath and the temperature of the alloy to be formed and precipitated. Is controlled in a specific range to produce an R-iron alloy made of a dysprosium-iron alloy, a terbium-iron alloy, or a dysprosium-terbium-iron alloy.

In the present invention, the temperature of the alloy that forms and precipitates is controlled to a specific range by using an electrolytic furnace provided with a heating means for heating at least the bottom surface of the electrolytic furnace by controlling the temperature of the electrolytic bath. Therefore, for example, R-^ gold with a suitable carbon content of 500 ppm or less as a magnet material can be manufactured more stably compared to the conventional method even if it is continuously operated for a long period of time, while suppressing composition fluctuations. can do.

In the present invention, first, an electrolysis apparatus including a DC electrode composed of an iron cathode and a graphite anode, and an electrolysis furnace having at least a heating means for heating the furnace bottom surface is described. Perform (A).

As the DC electrode composed of the cathode and the graphite anode, known DC electrodes and the like can be used.

The electrolytic furnace is provided with a heating means for heating an alloy to be precipitated at the bottom of the electrolytic furnace, which will be described later. Such a heating means may be any as long as it can heat at least the furnace bottom, and includes various heaters, various ¾fi bodies, etc. provided on the inner surface of the furnace bottom and on the outer surface of the furnace bottom. You. The heating means may be provided other than the furnace bottom in order to make the temperature of the entire electrolytic bath as uniform as possible. In addition, the electrolytic furnace is preferably covered with a thermal insulation layer in order to keep the temperature of the entire electrolytic bath as uniform as possible.

Since a general electrolytic furnace is constructed in such a manner that the bottom of the furnace is in contact with the base, the entire electrolytic furnace is kept at a constant level of heat, and more heat is radiated from the bottom of the electrolytic furnace than from the side of the electrolytic furnace. The temperature at the bottom of the electrolytic furnace is easily lowered. Therefore, in order to reduce the temperature difference between the upper part and the lower part of the electrolysis furnace, the heat insulation coefficient of the heat insulating layer must be kept constant at a low level. It is preferable to make the heat transmittance of the layer lower than that provided on the side surface.

The heat transfer coefficient (over-all heat transfer coefficient) is, according to “How to Learn Heat Transfer Engineering” published by Ohmsha (author Naokata Kitayama), the heat transfer when both heat conduction and heat transfer occur. It is defined as a coefficient indicating the ease of transmission, and is expressed by the following equation.

k = l / (l / hl + ∑ (δ / λ) + l / h2) Unit: W / (m ² K)

Here, hi is the thermal conductivity of the inner wall, δ is the thickness of the heat insulator, λ is the thermal conductivity of the heat insulator, and h2 is the heat conductivity of the outer wall.

Heat transfer coefficient of the heat-insulating insulation layer is preferably 0.5~3.0WZ (m ² K), more preferably 0.5 ~2.0WZ (m ² K), more preferably 0.5: a L0WZ (m ² K). The heat transfer coefficient is less than 0.5WZ (m ² K), Heat Insulation layer is thick, the electrolytic furnaces must be used small expensive material thermal transmittance in order to reduce the size of the force \ device upsizing However, it is not preferable because the equipment cost is high.

Examples of the material forming the heat insulating and heat insulating layer include irregular shaped refractory materials, refractory bricks, refractory heat insulating bricks, and ceramic firers.

The electrolytic furnace includes at least a metal layer in contact with an electrolytic bath, and the heat insulating layer provided outside the metal layer, and the heating means is provided on a bottom surface of the metal layer between the metal layer and the metal layer. Preferably.

The electrolytic furnace may be provided with an AC electrode for heating an electrolytic bath described later. By providing such an AC electrode, it is possible to perform a step of preheating the molten fluoride electrolytic bath to 900 to 970 ° C after the step (B) described later and before the step (C). become. In the present invention, in the electrolytic furnace, the direct current electrode, at least one rare earth fluoride of dysprosium fluoride and terbium fluoride, lithium fluoride and lithium fluoride can be used. Step (B) of introducing a fluoride molten electrolytic bath made of lithium is performed.

The fluoride molten electrolytic bath used in the step (B) is composed of electrolytic bath components and alloys such as dispersium fluoride and Z or terbium fluoride, and a solvent for the electrolyte, and as a heating medium for generating the zeolite. And lithium fluoride and barrier fluoride. With such an electrolytic bath, the melting point of the electrolytic bath can be kept within an appropriate range, and the generation of Joule heat during electrolysis can be easily controlled.

The composition of the electrolytic bath is preferably at least one rare earth fluoride of dysprosium fluoride and terbium fluoride, preferably 65 to 85%, and more preferably 10 to 20%, more preferably 10 to 20% by weight of lithium fluoride. 13-17%, preferably 5-15% barium fluoride, more preferably 8-15%.

If the content of lithium fluoride exceeds 20%, the electric resistance of the electrolytic bath decreases, and the Joule heat required for maintaining the electrolytic operating temperature may not be obtained, which is not preferable. On the other hand, when the content of lithium fluoride is less than 10%, the melting point of the electrolytic bath itself increases, which is not preferable.

Barium fluoride is added for the purpose of making the electrolytic bath itself difficult to coagulate. The electrolytic bath is very easy to coagulate without the addition of parium fluoride, and solidifies immediately when the temperature drops below the melting point. The coagulation rate can be reduced by adding a suitable amount of parium fluoride. If the content of barium fluoride is less than 5%, the effect of the above addition is small, and if it exceeds 15%, the melting point of the electrolytic bath increases, which is not preferable.

When using both dysprosium fluoride and terbium fluoride as the rare earth fluoride, the content ratio of these in the rare earth fluoride is not particularly limited, but the weight ratio of dysprosium fluoride: terbium fluoride is usually 1 to 1. 99: 99-; 1, particularly preferably 30-70: 70-30.

In the present invention, next, in order to generate an R-iron alloy and precipitate the alloy at the furnace bottom of the electrolytic furnace, electrolytic reduction using a raw material of disposable fluoride and Z or terbium fluoride as a raw material ( Perform C).

In order to perform the electrolytic reduction in the step (C), it is necessary to maintain the temperature of the electrolytic bath between the DC electrodes at 900 to 970 ° C, preferably 920 to 950 ° C. This range is a range in which a suitable alloy composition can be obtained as a magnet alloy raw material, and also a temperature range in which the electrolytic operation can be stably continued. If this temperature is lower than 900 ° C, the amount of crystallization increases, When collecting the alloy, it causes a trap such as solidification and inability to recover.If the temperature exceeds 970 ° C, the anodic effect tends to occur, making it difficult to continue the electrolytic reaction and increasing the amount of carbon contained in the alloy. There is fear.

Here, the temperature of the electrolytic bath means a temperature measured at a specific portion of the electrolytic bath between the DC electrodes. The specific portion is not particularly limited as long as it is between the electrodes, but is usually a central portion between the electrodes.

In the step (C), the temperature of the alloy to be formed and precipitated is maintained at 850 to 1000 ° C., preferably 870 to 960 ° C. by maintaining the temperature of the electrolytic bath and by the heating means provided in the electrolytic furnace. Perform heating control within the range. Here, the temperature of the alloy means the value of the temperature of the alloy that has settled 2 to 4 cm from the furnace bottom in the center of the electrolytic furnace, measured using a sheath-type K thermocouple.

Further, in step (C), the temperature of the precipitated alloy is 850-: 1000. The electrolytic reduction is preferably performed by controlling the heating means so that the temperature is in the range of C and the temperature of the electrolytic bath between the DC electrodes is within a range of ± 50 ° C., particularly ± 30 ° C. By controlling the temperature of the electrolytic bath between the DC electrodes and the ^^ of the precipitated alloy in this way, more stable long-term operation becomes possible. Such control can be performed by controlling the potential between the electrodes and the temperature by a heating means while measuring each temperature at predetermined intervals.

In the electrolytic reduction in the step (C), the potential between the direct-current electrodes is preferably controlled, for example, by providing a reference electrode in an electrolytic furnace and controlling the anode potential to the Fuchich electrolytic potential. It is desirable to be in the range of 4.0 to 7.0V. By controlling the anodic potential to the fluoride electrolytic potential, the occurrence of the anodic effect is suppressed, and a long-term continuous operation can be more reliably achieved.

In the electrolytic reduction in the step (C), dispersium fluoride and terbium fluoride as alloy raw materials in the electrolytic bath are reduced, so that the reduction reaction proceeds. When the concentration of the dysprosium fluoride and / or terbium fluoride decreases, the electric resistance of the electrolytic bath decreases, the streak generated between the electrodes also decreases, and it becomes difficult to maintain the operating temperature, and the anode effect occurs. And it becomes difficult to maintain operations. Therefore, they need to be combined. The additional disposable fluoride and / or terbium fluoride can usually be used in the form of powder or pellets. Although the amount of raw material input is large, the bath temperature may be partially lowered and the electrolysis operation may be hindered.Therefore, an appropriate amount of raw material should be considered in consideration of the amount of electricity supplied and the electrolytic efficiency. It is preferable to continuously feed the pulp. Also, it is preferable to feed the raw material into the electrolytic bath between the electrodes, which generates the necessary time for maintaining the operation and destruction, has the highest temperature of the electrolytic bath, and is most suitable for dissolving the raw material. If the amount of the raw material is adjusted, the raw material can be charged in a place other than between the electrodes, but it is not preferable because the temperature segregation in the electrolytic bath increases.

In the present invention, by performing the step (D) of recovering the H-iron alloy precipitated in the step (C), an R-iron comprising a desired iron-dispersion alloy, a terbium iron alloy or an iron dysprosium-terbium alloy is obtained. An alloy can be obtained.

The alloy can be recovered even in the middle of the step (C), and can be recovered from the upper or lower part of the electrolytic furnace by a conventional method.

In the present invention, since the above-described steps (A) to (D) are performed, a high-grade R-iron alloy having a small composition variation and a small content of impurities such as carbon at the mounting level can be obtained more stably than before. It can be obtained continuously for a long time. Further, in order to obtain a range that does not impair the effects of the present invention or other desired effects, the manufacturing method of the present invention may include other steps other than the above steps.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

Example 1

Using the electrolysis apparatus 10 shown in FIG. 1, electrolytic reduction was performed by the following method. As shown in the figure, the electrolysis device 10 includes an iron cathode 11, a graphite anode 12, and an iron AC electrode 13.A heat insulation layer 16 is provided around the iron electrolysis furnace 1 via a magnesia backup 15. I can. In FIG. 1, reference numeral 7 denotes a furnace lid, reference numeral 18 denotes an electrolytic bath, and reference numeral 19 denotes a formed alloy. The electrolyzer 10 is provided with a heater for heating the metal at the bottom of the metal layer between the electrolysis 14 of m as a metal layer and the magnesia backup 15 provided inside the break 16, that is, at the bottom of the electrolytic furnace. Not shown).

«Heat transfer rate made of firebrick (Nitsukatone: fc, firebrick) and ceramic fiber (Nichias, Fineflex hardboard) as heat insulation layer 16 First, as the electrolytic bath 18, 12 kg of an electrolytic bath having a weight ratio of DyF ₃ : LiF: BaF _{2 of} 75:15:10 was charged into the electrolytic furnace 14 using a heat insulating layer of 0.55 W / (m ² K). Then, the AC electrode 13 was energized to heat and dissolve the electrolytic bath 18.After the temperature of the electrolytic bath 18 was stabilized at 930 ° C, the AC electrode was de-energized, and the DC electrode (graphite anode 12 and iron AC electrode 13 ), The electrode potential was 7.9 V (the anode potential was 6.3 V (measured using a reference electrode (not shown)), and a current of 160 A was applied to perform the electrolytic reduction. (The temperature between the graphite anode 12 and the iron AC pole 13) and the temperature of the formed alloy 19 at the bottom of the electrolytic furnace are measured at predetermined intervals, and one hour after two hours from the energization when the alloy can be collected Every other alloy was sampled and analyzed for composition to evaluate the presence or absence of intermediate products and the stability of the alloy composition, and also observed the presence or absence of the anodic effect during operation. It is shown in Fig. 1. In addition, as the DyF ₃ of the electrolytic bath decreased during operation, the electrolytic bath between the electrodes was appropriately changed. P DyF ₃ was introduced.

The “alloy composition stability” shown in Table 1 is defined as “stable” when the iron component in the alloy produced through the electrolytic operation is within ± 3% of the target composition, and “unstable” when the change is greater than that. Stable. " The average temperature of the electrolytic bath in Table 1 indicates the average value of the electrolytic bath temperature between the electrodes measured at 10-minute intervals during the 10-day electrolytic operation, and the average alloy temperature indicates the 10-day electrolytic operation. The average value of the temperature of the alloy precipitated at about 3 cm from the furnace bottom in the central part of the electrolytic furnace through a 10-minute interval using a sheath-type K thermocouple is shown. Further, the maximum temperature difference is a value of the largest difference between the electrolytic bath temperature between the electrodes measured at 10-minute intervals throughout the electrolytic operation for 10 days and the actual alloy temperature at the average alloy temperature.

In this example and in Examples 2 to 8 described later, the measured electrolytic bath temperatures between the electrodes were all within the range of 900 to 970 ° C, and the measured alloy temperatures were all 850 to 1000 ° C. Was within the range. ,

Examples 2 to 8 and Comparative Examples 1 to 4

Each of the thermal insulation layer 16 and the electrolytic bath 18 was subjected to electrolytic reduction in the same manner as in Example 1 except that the bath shown in Table 1 was used and the electrolysis conditions and bath composition shown in Table 1 were used. Table 1 shows the results. Here, when TbF ₃ was contained as a bath composition, electrolytic reduction was performed by appropriately adding TbF _3, which was reduced with electrolytic reduction, in the same manner as in the case of adding DyF ₃ in Example 1. In Table 1, the material of the thermal layer is a castable refractory (hereinafter referred to as refractory) made of Harima ceramics: h¾ as an irregular refractory material, and a fire-resistant insulation brick (hereinafter referred to as a brick) converted from Nitsukato as a refractory brick. As a ceramic firer-Chiasune: Fine Flex Hard

Claims

The scope of the claims

Β step (A) of an electrolysis apparatus provided with a DC electrode comprising an iron cathode and a graphite anode, and an electrolysis furnace having at least a heating means for heating the furnace bottom;

Introducing, into the electrolytic furnace, the DC electrode and a fluoride molten electrolytic bath composed of at least one rare earth fluoride of dysprosium fluoride and terbium fluoride, lithium fluoride and parium fluoride. When,

In order to produce an R-iron alloy (R stands for disposable, terbium or disperse terbium) and precipitate the alloy at the bottom of the electrolytic furnace, at least one of a dysprosium fluoride and terbium fluoride is used as a raw material. Electrolytic reduction step (C),

Recovering the R-iron alloy precipitated in the step (C) (D),

The electrolytic reduction in the step (C) is performed by adjusting the temperature of the electrolytic bath between the DC electrodes to 900 to 970. A method for producing an R-iron alloy, wherein the method is carried out under the condition of maintaining the temperature at C and controlling the temperature of the precipitated alloy within the range of 850 to 1000 ° C by the heating means provided in the electrolytic furnace.

The electrolytic reduction in the step (C) is performed so that the temperature of the precipitated alloy is in the range of 850 to 1000 ° C and the temperature of the electrolytic bath between the DC electrodes is in the range of ± 50 ° C. The production method according to claim 1, wherein the production method is controlled by a heating means.

The electrolytic furnace in step (A) includes at least a metal layer in contact with the electrolytic bath and a heat insulating layer provided outside the metal layer, and the metal layer and a metal layer bottom between the heat insulating layer. 2. The method according to claim 1, wherein said heating means is provided on a surface.

The electrolytic furnace to be glued in the step (Α) includes a metal layer in contact with the electrolytic bath and a heat insulating and heat insulating layer provided outside the metal layer, and the heat transfer rate of the insulating layer is 0.5 to 3.0 W /. (m ² K).

The electrolytic furnace in the step (A) is provided with an AC electrode for heating the electrolytic bath, and after the step (B) and before the step (C), the molten electrolytic bath of the fluoride by the AC electrode is 900 to The production method according to claim 1, wherein a step of heating to 970 ° C is performed.

In the step (B), the composition of the electrolytic bath introduced into the electrolytic furnace is 65 to 85% of rare earth fluoride composed of at least one of dysprosium fluoride and terbium fluoride, and 10 to 20% of lithium fluoride. And the barium fluoride is 5 to 15%.

The rare earth fluoride is dysprosium fluoride and terbium fluoride, and the content ratio of the rare earth fluorides in the rare earth fluoride is as follows: dysprosium fluoride: terbium fluoride = 1-99: 99-1 The method of claim 6.

2. The method according to claim 1, wherein the electrolytic reduction in the step (C) is performed by controlling the anode potential to a fluoride electrolytic potential using a reference electrode.

9. The method according to claim 8, wherein the fluoride electrolytic potential is 4.0 to 7.0 V.