JPH02228433A - Production of rare earth metal or rare earth metal-transmission metal alloy - Google Patents

Abstract

PURPOSE:To satisfactorily separate a formed metal from slag by carrying out slag melting by the use of a water-cooled metallic vessel and also using a flux with low melting point other than a Ca-type reducing agent at the time of melting and reducing a raw material for rare earth metal in the slag. CONSTITUTION:A raw material for rare earth metal or a raw material prepared by further adding a raw material for transition metal to the above raw material is melted and reduced together with a Ca-type reducing agent in slag by means of the resistance heat generation of the slag, by which a rare earth metal or a rare earth element - transition metal alloy is produced. At this time, a water- cooled metallic vessel is used for the melting of the slag, and a low-m.p. flux selected from the halides (MgF2, BaF2, etc.) of alkali metals or alkaline-earth metals is used other than the Ca-type reducing agent, and slag bath temp. is regulated to 1000-1500 deg.C, and then, reducing reaction is, carried out at a temp. at which a formed Ca-type product can be melted. By this method, the metal formed by reduction can be satisfactorily separated from the slag, and the formed metal or alloy can be continuously obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing rare earth metals and rare earth metal-transition metal alloys.

(Prior Art) There are two methods for producing rare earth metals: an electrolytic process and a metal thermal reduction process.

The electrolytic process involves the decomposition of anhydrous rare earth chlorides dissolved in molten alkali or alkaline earth chloride salts or ? There is decomposition of rare earth oxides dissolved in 8-fused fluoride salts.

Disadvantages of the electrolytic process include the use of anhydrous chlorides or fluorides to prevent the formation of undesirable rare earth oxysalts, low metal recovery from salts (less than 40% metal recovery), and the use of chlorine during rare earth chloride electrolysis. Gas may be generated.

On the other hand, metal thermal reduction processes include reduction of rare earth fluorides with calcium metal and reduction and diffusion of rare earth oxides with calcium hydride or calcium metal.

However, since both methods are batch-type, only a small amount of metal can be obtained at a time, and in the metal thermal reduction process, T
It is necessary to use an expensive crucible such as A or A, and there are also problems such as contamination of crucible materials, which makes it difficult to implement as an industrial method.

Therefore, in the production method of this type of rare earth, there was an urgent need to establish an inexpensive and continuous production method that uses conventional expensive crucibles and replaces the batch method. Separation of reduced metal and slag is one of the important issues.

As an improvement of this separation method,
No. 32 is proposed.

(Problems to be Solved by the Invention) This conventional method proposes a method of keeping the slag in a molten state at a high temperature of 1500'C or more and carrying out a reduction reaction as a method for separating the reduced metal and slag. There is. However, this method requires the reduction reaction to take place at high temperatures;
The evaporation and scattering of metal Ca, which is a reducing agent, becomes large, which is not only uneconomical but also causes poor reduction.

On the other hand, in order to prevent this, if the reduction reaction temperature is lowered and the reduction reaction is carried out in semi-molten slag, the reduced metal and slag are remelted at a high temperature and the produced metal and slag are separated. In addition, when creating an alloy of rare earth metals and transition metals, new remelting is required, which is also an obstacle to continuous reduction reactions. There's a problem.

Furthermore, if a large amount of inexpensive rare earth oxide is used as the rare earth metal raw material, the amount of oxide in the slag will increase and the melting point of the slag will increase. For this reason, a problem arises in that the amount of use thereof is also limited.

(Means for Solving the Problems) The present invention provides rare earth metals or rare earth metals as described above.
As far as the problem of the production method of transition metal alloys is concerned, in order to facilitate the separation of the reduction product metal and slag, the relationship between the slag components and the melting point was studied in detail, and the ratio was regulated. This invention was completed based on the knowledge that the reduction reaction can be carried out at a temperature of 1500°C or less and that the metal produced by the reduction and the slag can be easily separated.The first invention is as follows:
To obtain a rare earth metal or a rare earth metal-transition metal alloy by melting and reducing a rare earth metal raw material or a transition metal raw material added thereto together with a Ca-based reducing agent in a slag due to resistance heat generation of the slag, melting of the slag is performed. was carried out using a water-cooled metal container, and in addition to a Ca-based reducing agent, a low melting point flux selected from alkali metal or alkaline earth metal halides was used, and the slag bath temperature was increased to 10°C.
This is a method for producing rare earth metals or rare earth metal transition metal alloys, in which the reduction reaction is carried out at a temperature selected from the temperature range of 00 to 1500''C and at which the Ca-based compound produced as a result of the reduction reaction in the slag melts.

A second invention is the manufacturing method according to claim (1), wherein as the electrodes used for resistance heating, a non-consumable electrode is used when producing a rare earth metal, and a consumable electrode made of a transition metal is used when producing a rare earth metal transition metal alloy.

The third invention uses a rare earth oxide as a rare earth metal raw material.
Claims using rare earth halides containing 0-L% or less (
This is the manufacturing method of 1) or (2).

A fourth invention is the manufacturing method according to claim (1), (2) or (3), wherein the rare earth metal raw material, reducing agent and flux are continuously supplied into a slag bath to advance the reduction reaction.

A fifth invention is a claim (1) in which the rare earth metal or rare earth metal-transition metal alloy produced by reduction is continuously pulled out from the bottom of the water-cooled container.
), (2), (3) or (4).

(effect) Hereinafter, the effects of the present invention will be explained in detail.

First, the gist of the present invention will be explained.

The point of this case is the following reduction reaction NdzO3+3Ca →3CaO+2Nd2NdF3+ that progresses in the slag.
3Ca-3CaFzMo2Nd is produced in a state where CaO and CaFz having a high melting point are in a liquid state.

That is, if the slag is solid, CaO, CaFz and Nd
This results in a semi-molten state in which the rare earth metal is mixed with the liquid, and although it is possible to reduce the rare earth metal, it becomes difficult to separate the rare earth metal from CaO, CaFz, and re-melting at a high temperature is required as a post-process.

However, in order to avoid this, if the reduction reaction temperature is raised, the evaporation and scattering of metal Ca, which is the reducing agent, will increase.
This is not only uneconomical but also causes poor returns.

In order to prevent these, the main idea is to lower the melting point of the slag and to cause the reduction reaction to occur in the completely molten slag, by adding a flux that produces slag with a low melting point to the slag. It is.

Next, each prescribed condition of the present invention will be described in detail.

Conventionally, crucibles made of high melting point metals such as Ta, -, etc., which are expensive and can only yield small products, have been used.
Therefore, in the present invention,
A water-cooled metal container is used as an alternative to a crucible.

The water-cooled metal container is, for example, a water-cooled copper container, and the bottom of the container can be separated from the side wall of the container and pulled out downwards, so that the reduced metal solidified at the bottom of the water-cooled copper container can be continuously drawn out. .

The present inventors have proposed that by adding an alkali metal or alkaline earth metal halide, such as hgpz, BaFz, to the slag, Ca generated by reduction of the oxide can be reduced.
It has been found that the melting temperature of slag containing O can be lowered, and in the present invention, the slag bath temperature is 1000
The temperature was set at ~1500°C.

The slag bath temperature needs to be higher than the melting point of the metal or alloy produced by the reduction and the melting point of the slag, but it is preferably as low as possible in terms of energy consumption and fume suppression. However, below 1000'C, the viscosity of the slag becomes low, making it difficult to separate the slag and the produced metal. Moreover, when the temperature exceeds 1500° C., fumes are generated violently, metal Ca, which is a reducing agent, evaporates and scatters to a large extent, and reduction of rare earth oxides with metal Ca becomes thermodynamically difficult.

In addition, among the rare earth compounds used as raw materials for rare earth metals, oxides are cheaper than fluorides and chlorides, so
It is desirable to use as many oxides as possible in the rare earth metal raw material. However, as the oxide content in the raw material increases, the reducing agent oxide CaO produced by the reduction reaction increases.
increases in the slag, and the melting point and viscosity of the slag increase accordingly. However, in order to keep the slag in a molten state and maintain good separation between the produced metal and the slag, it is necessary to keep the content of oxides in the slag at 25 wt% or less. Therefore, the rare earth oxide in the rare earth metal raw material was specified to be 80 wt% or less.

Regarding electrodes, when manufacturing rare earth metals, W
, Mo, Ta, etc., non-consumable t made of a metal or alloy that has a high melting point and does not form a low melting point alloy with rare earth metals.
Use i. On the other hand, when producing a rare earth metal-transition metal alloy, depending on the desired transition metal, for example,
A consumable electrode made of a transition metal such as Fe, Go, or Ni is used. The consumable electrode dissolves into the rare earth metal during the reduction reaction and forms a rare earth metal-transition metal alloy.Instead of using the consumable electrode, the transition metal or its compound may be supplied to the slag bath as a raw material. You can.

As described above, in the present invention, since the melting point of the slag is suppressed to a low level, the reduction product metal and the slag can be separated well, so that the reduction reaction can proceed continuously.

Therefore, in the present invention, the rare earth metal raw material, the reducing agent, and the flux are continuously supplied into the slag bath according to the capacity of the water-cooled metal container to allow the reduction reaction to proceed, thereby obtaining the reduction product metal.

Furthermore, since the water-cooled metal container according to the present invention has a structure in which the bottom part can be separated from the side wall of the container and pulled out downward, the reduction reaction can proceed continuously and the metal produced by the reduction can be continuously drawn out from the bottom of the water-cooled metal container. .

Incidentally, rare earth metals and alkali metals and alkaline earth metals which are reducing agents are very active, so they react with oxygen in the II concavity, causing re-oxidation of the reduction product metal and oxidation loss of the reducing agent. For this reason, the inside of the manufacturing equipment must be isolated from the atmosphere and the reduction reaction must be carried out in a non-oxidizing atmosphere.
It is preferable to carry out this process in a reducing atmosphere containing gas.

In addition, from the perspective of suppressing the evaporation and scattering of the reducing agent,
It is desirable to increase the atmospheric pressure within the manufacturing equipment, but the atmospheric pressure within the manufacturing equipment is substantially 1 to 3 kgf.
/cmz is sufficient.

The manufacturing equipment will be explained below.

FIG. 1(a) is a cross-sectional view of a manufacturing apparatus in which the bottom of a water-cooled copper container is fixed, where 1 is a water-cooled copper container, 2 is an electrode, 3 is a container, and 4
is the power supply, 5 is the vacuum pump, 6 is the atmospheric gas inlet, 7 is the atmospheric gas outlet, and 8 is the ? ? I molten slug slag indicates the produced molten metal, 10 indicates the produced metal, and 14 indicates the raw material supply port.

FIG. 1(b) is a schematic diagram of a manufacturing apparatus in which the bottom of a water-cooled copper container is fixed, where ■ is a water-cooled copper container, 2 is an electrode, 3 is a container, and 4 is a water-cooled copper container.
1 is a power source, 6 is an atmospheric gas inlet, 11 is a raw material supply screw, 12 is a motor, and 13 is a raw material hopper.

Fig. 2 is a cross-sectional view of a manufacturing device in which the bottom of a water-cooled copper container is movable, where 1 is a water-cooled steel container, 2 is an electrode, 3 is a container, 4 is a power source, 6 is an atmospheric gas inlet, and 7 is a water-cooled steel container. Reference numeral 8 indicates a molten slag, 9 indicates a produced molten metal, 10 indicates a produced metal, 14 indicates a raw material supply port, 15 indicates a movable bottom of the water-cooled copper container, and 16 indicates a guide.

As shown in FIG. 1, the inside of the manufacturing equipment is isolated from the atmosphere by a water-cooled copper container 1 and a container 3. Prior to manufacturing, the atmospheric gas inside the equipment is exhausted by a vacuum pump 5, and then the atmospheric gas is Non-oxidizing gas is introduced from the inlet 6. Excess gas is also exhausted from the atmospheric gas exhaust lobe.

The electrode 2 can be used as either a non-consumable electrode or a consumable electrode depending on the type of metal produced.

After the raw material and reducing agent are well mixed, the raw material hopper 13
The molten slag 8 is sequentially moved to the raw material supply port 14 via the raw material supply screw 11 by the rotation of the motor 12, and is charged into the molten slag 8 from the raw material supply port 14.

The molten slag 8 is heated by the electrode 2 by electricity supplied from the power supply 4, and the input raw materials and reducing agent cause a reduction reaction in the molten slag 8, and the metal produced by reduction is separated from the molten slag 8, and the produced molten metal is separated from the molten slag 8. [9], and then, as the reduction reaction progresses, it solidifies to become the generated metal IO.

The manufacturing apparatus shown in FIG. 2 is a water-cooled copper container 1 with a movable bottom, allowing the reduction reaction to proceed continuously.
The produced metal 10 can be pulled out downward along a guide 16 together with a movable bottom 15 of the water-cooled copper container.

(Example) Although the configuration of the present invention is as described above, an example will be described below.

Example 1 A water-cooled metal container contains 41g90III+, length 19
A water-cooled copper container 1 with a height of 300 I and an oval-shaped bottom of 0 mm was used, and the initial slag contained 80 wt% of CaFz.
, CaO2Qwt% was used.

As the raw material, 8 kg of a mixture consisting of 75 wt% of NdFs with a purity of 95% or higher and 25 wt% of NdzOs with a purity of 95% or higher is used, and as a reducing agent, 3 kg of metallic Ca is used. I loaded it.

Next, the initial slag was charged into the water-cooled copper container 1, the non-consumable electrode 2 was inserted into the slag, and electricity was applied between the electrodes to melt the slag.

A voltage of 25 V and a current of 1200 A are passed between the electrodes, the slag bath temperature is maintained at 1400° C., and the raw material and the reducing side are thoroughly mixed from the raw material hopper 13 through the raw material supply screw 11 and from the raw material supply port 14. While feeding a total of 8 kg into the molten slag 8 at a rate of 30 g/min, about 4 kg
The original reaction was continued for 30 minutes.

Note that the atmosphere inside the manufacturing apparatus is Ar gas at 1 atm.

As a result, a 4.2 kg metal Nd lump was obtained. The analytical values are shown in Table 1. Table 1 also shows analytical values for commercially available Nd as a comparative example.

As shown in Table 1, the metal lid of Example 1 is no inferior to that of the comparative example, and the example shows lower values for impurity elements 0, Fe, and Si.

Table 2 shows the manufacturing conditions and manufacturing results of Examples 2 to 8, which were carried out using the same manufacturing equipment as Example 1.

(The following is a blank space) Table 2 shows the raw materials, reducing agents, fluxes, atmospheres in the apparatus, electrodes used, slag bath temperatures, currents, voltages, produced metals, and yields of Examples 2 to 8.

Example 2 Raw materials NdxOs 1.7kg, NdPs 5.3kg
, using 2.5 kg of reducing agent Ca in an atmosphere of 1 atm of Ar gas, and without using a consumable Fe electrode, the particle size of the raw material was 14.
Using 0.8 kg of iron powder of 9 μm or less, Nd-15%F
e-alloy was produced. The yield was 4.1 kg.

Example 3 Raw materials NdzO 32.5 kg, NdFs 2.5 kg,
Reducing agent Ca1.8kg, flux BaFz 1kg
, using 0.5 kg of CaFz, Ar-10% H2
Using a consumable Fe electric scraper in a gas atmosphere of 1 atm,
A Nd-18%Fe alloy was manufactured.

The total amount was 3.7 kg.

Example 4 A Nd-22% Fe alloy was produced using a consumable Kpe electrode in an atmosphere with a total gas pressure of 1.5 atmospheres using 1 kg of raw material Nd, Oz, 5 kg of NdFs, and 2.2 kg of reducing agent Ca. The yield was 5.6 kg.

Example 5 Using 1 kg of raw material PraO++, 5 kg of PrFi, and 2.2 kg of reducing agent Ca, pure Pr was produced using a non-consumable electrode in an Ar gas atmosphere of 1 atm.

The yield was 4.7 kg.

Example 6 Raw materials Pr60++ 3kg, Prh 1.8kg,
Reducing agent Cal.

7 kg, using 4 kg of flux CaCIt,
A Pr-18% Fe alloy was manufactured using a consumable Fe1i electrode in an Ar gas atmosphere of 1 atm. Its yield is 3
．． It weighed 8 kg.

Example 7 Raw material GdzOs 1.5kg5GdFs 5.5kg,
Pure Gd was produced using 2.5 kg of reducing agent Ca and a non-consumable electrode in an Ar gas atmosphere of 1.5 atm. The yield was 5.2 kg.

Example 8 Raw material Tbn0t 3kg, TbF32.5kg, reducing agent Ca 2kg, flux BaFz 2.5kg 5
A Tb-21% Fe alloy was produced using 1 kg of CaFx and a consumable Fe electrode in an Ar gas atmosphere of 1 atm. The yield was 4.9 kg.

Note that the slag bath temperatures in Examples 2 to 8 were all 1200°C ~
The temperature range is 1400°C, which satisfies the specified value of the present invention.

Example 9 The water-cooled metal container has a width of 801 WI11 and a length of 160 mm.
A water-cooled copper container 1 with a height of 350 mm and an oval-shaped movable bottom was used. The movable bottom portion 15 of this water-cooled copper container is structured so that it can be separated from the side wall of the container and pulled out downward along a guide 16.

The initial slag contains CaF, 80 wt%, CaO20
500 g of slag consisting of wt% was used.

As a raw material, 12 kg of a mixture consisting of 75 wt% of NdFz with a purity of 95% or higher and 25 t% of NdzOs with a purity of 95% or higher was used, and as a reducing agent, 4.5 kg of metallic Ca was used.
These were thoroughly mixed using a , and charged into the raw material hopper 13 .

Next, the initial slag was charged into the water-cooled copper container 1, and the non-consumable W1 electrode 2 was inserted into the slag, and electricity was applied between the electrodes to melt the slag.

A voltage of 22 V and a current of 1000 A are passed between the electrodes, the slag bath temperature is maintained at 1400° C., and the mixture of raw material and reducing agent is thoroughly mixed from the raw material pumper 13 through the raw material supply screw 11 and from the raw material supply port 14. While a total of 12.5 kg was introduced into the molten slag 8 at a rate of 40 g/min, the rapid reaction was continued for about 5 hours and 30 minutes.

During this time, the movable bottom portion 15 of the water-cooled copper container was intermittently pulled downward by a total of 60 vo along the guide 16.

Note that the atmosphere inside the manufacturing apparatus is Ar gas at 1 atm.

As a result, a 6.6 kg metal Nd ingot with a height of 90+m+* and an oval shape with a width of 78I and a length of 1561III11 was obtained.

In this way, the reduction reaction can be continued and the reduction product metal can be continuously produced.

Further, as shown in Example 1, the impurities in the metal produced by the final method are very low.

(Effects of the Invention) As explained above, the method for producing rare earth metals or rare earth metal-transition metal alloys according to the present invention uses a water-cooled metal container instead of a crucible, so that the produced metals from metals such as Ta Also, since the contamination of the alloy is very low, and since the slag with a low melting point is used, the separation between the produced metal or alloy and the slag can be performed well, so the reduction reaction can proceed continuously. In addition to being able to produce metals or alloys, many rare earth oxides can be used as rare earth metal raw materials, and furthermore, rare earth metal-transition metal alloys can be easily produced by using electrodes made of transition metals. Can be done.

As described above, the method for producing a rare earth metal or rare earth metal-transition metal alloy according to the present invention has many excellent effects.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a manufacturing apparatus in which the bottom of a water-cooled copper container is fixed, in which (a) is a sectional view thereof, and (b) is a schematic diagram thereof. FIG. 2 is a sectional view of a manufacturing apparatus in which the bottom of a water-cooled copper container is movable. 1 - Water-cooled copper container 2 - Electrode 3 - Container 4 - Power supply 5 - Vacuum pump 6 Atmosphere gas inlet - Atmosphere gas outlet 8 - Molten slag 9 - Produced molten metal 10 - Produced metal 11 - Screenie for raw material supply 12 - Motor 13 - Raw material hotspot 14 - Raw material supply port I5 - Movable bottom of water-cooled copper container 16 - Guide Patent applicant Kobe Steel Co., Ltd. Representative Patent attorney Yomitsu Akira - Figure 2 Figure 1 (b )

Claims (5)

[Claims] (1) To obtain a rare earth metal or a rare earth metal-transition metal alloy by melting and reducing a rare earth metal raw material or a transition metal raw material added thereto together with a Ca-based reducing agent in a slag due to resistance heat generation of the slag, The slag is melted using a water-cooled metal container, and in addition to a Ca-based reducing agent, a low melting point flux selected from alkali metal or alkaline earth metal halides is used to maintain the slag bath temperature at 1000 to 1500°C. A method for producing a rare earth metal or a rare earth metal-transition metal alloy, which comprises carrying out the reduction reaction at a temperature selected from a temperature range and at which a Ca-based compound produced as a result of the reduction reaction in the slag melts. (2) As the electrode used for resistance heating, a non-consumable electrode is used when producing a rare earth metal, and a consumable electrode made of a transition metal is used when producing a rare earth metal-transition metal alloy.
1) Manufacturing method. (3) 80wt of rare earth oxide as rare earth metal raw material
% or less of a rare earth halide. (4) A claim in which the rare earth metal raw material, reducing agent, and flux are continuously supplied into the slag bath to advance the reduction reaction (
1), (2) or (3) manufacturing method. (5) The rare earth metal or rare earth metal-transition metal alloy produced by reduction is continuously drawn out from the bottom of the water-cooled container.
2), (3) or (4) manufacturing method.