JPS62222094A - Method and apparatus for producing yttrium alloy - Google Patents

Abstract

PURPOSE:To efficiently produce an yttrium alloy by electrolytically reducing yttrium fluoride in a molten salt electrolytic bath with a cathode of a metal capable of being alloyed with yttrium and a carbon anode and by depositing the resulting yttrium on the cathode. CONSTITUTION:Yttrium fluoride is electrolytically reduced in a molten salt electrolytic bath with a cathode of a metal capable of being alloyed with yttrium and a carbon anode. The resulting yttrium is deposited on the cathode and alloyed with the metal forming the cathode to produce a prescribed yttrium alloy. The molten salt electrlytic bath is composed of, by weight, 20-93% yttrium fluoride, 7-80% lithium fluoride, <40% barium fluoride and <20% potassium fluoride.

Description

Detailed Description of the Invention (Technical Field) The present invention relates to a method for manufacturing yttrium alloys such as yttrium-nickel alloys and yttrium-iron alloys, and a manufacturing apparatus therefor, and particularly to a method for continuously manufacturing a master alloy for rare earth-added alloys. The present invention relates to a method and an apparatus for doing so.

(Background of the Invention) Yttrium metal is used as an additive to steel and other metals, and is attracting attention as an additive for metal materials for special purposes, such as improving oxidation resistance, and the demand for yttrium is expected to increase in the future. This is expected to increase. However, when adding this yttrium metal, the melting point of the yttrium metal is 1.
Since the temperature is as high as 5°C, it is thought that a master alloy with nickel or iron is more advantageous in terms of handling.

By the way, the following four methods are generally known as methods for producing alloys of rare earth metals and high melting point metals.

First, rare earth metals are produced by molten salt electrolysis or reduction with active metals (removed as rare earth metals or alloys thereof), mixed with other metals, and dissolved.
This is a method of alloying. However, among these methods, when chloride is used as the raw material for electrolysis, handling of the raw material is difficult, and the operation is batch-type. There is a problem with that. Furthermore, when oxides of rare earth metals are electrolyzed using a fluoride electrolytic bath, the solubility of such oxide raw materials in the electrolytic bath is low, which makes continuous operation difficult, and sludge is formed at the bottom of the electrolytic bath. There is an inherent problem. In particular, in order to achieve mass production and continuous operation, it is preferable that the produced metal be in a liquid state, but in the case of high-melting-point rare earth metals, it is necessary to raise the electrolysis temperature to achieve this. Impurities tend to mix into the produced metal, making it impractical.

On the other hand, the above method, which includes the step of reducing rare earth metal raw materials using active metals, has problems in that the operation is batch-type and is not suitable for continuous large-scale production. use, requires expensive materials for reduction equipment,
Further, there are inherent problems in that the process is complicated, such as the need for a process to remove residual reducing agent components.

The second method is to mix a rare earth metal compound and a metal compound to be alloyed and reduce the mixture with an appropriate compound (for example, calcium hydride in the case of producing an Sm-Co alloy); , using expensive reducing agents;
There are problems such as the fact that the operation is batch-type and is not suitable for continuous large-scale production.

Furthermore, thirdly, a method in which a compound of a rare earth metal and a compound of a metal to be alloyed are melted in an electrolytic bath by molten salt electrolysis, and both compounds are electrolytically reduced and deposited as an alloy on a cathode (for example, Japanese Patent No. 3298935), but this method also has the following problems. In other words, it is difficult to stabilize the composition of the alloy deposited on the cathode over a long period of time during the electrolytic process, and when oxides are used as raw materials, the solubility of the raw materials in the electrolytic bath is low, making continuous operation difficult. There are inherent problems such as difficulty in

The fourth method is the so-called consumable electrode method, in which the metal to be alloyed is used as a solid cathode, while the rare earth metal compound is dissolved in an electrolytic bath of a suitable molten salt. A method (U, S,
See Bureau of Mines, Report Op Investigations, Yang 7146 (1968), Patent No. 837401, Patent No. 967389, etc.]
It is.

However, even this method has the following drawbacks. In other words, when an oxide raw material is used as a rare earth metal compound to be electrolytically reduced, as mentioned above, there are problems such as low solubility of the oxide in the electrolytic bath and the formation of sludge. There is a problem, and high temperature operation is required to avoid this problem. However, when this high-temperature operation is performed, a new problem arises in that impurities from the furnace materials and the like increase, degrading the quality of the produced alloy.

Moreover, in this consumable electrode method, the produced alloy is collected in a batch manner, etc., and is not continuous, and only the part where the cathode is immersed in the electrolytic bath needs to be divided into multiple parts ( Japanese Patent No. 967389) also has inherent problems such as the impossibility of continuous use of the cathode, making it unsuitable for mass production.

Under such circumstances, yttrium metal has had almost no use so far, and the reduction method in the first method mentioned above may be considered as a method for producing it in small quantities, but no industrial method for continuously producing it is sufficient. has not been established.

(Summary of the Invention) The present invention has been made against the background of the above, and its purpose is to produce yttrium alloys such as yttrium-nickel alloys and yttrium-iron alloys on a large scale. Another object of the present invention is to provide a method and apparatus for continuously producing yttrium alloys with a high yttrium content and a low content of impurities and inclusions. The object of the present invention is to provide a reliable and economical industrial manufacturing method and apparatus.

That is, in order to achieve the above object, the present invention electrolytically reduces a yttrium compound in a molten salt electrolytic bath using a solid cathode made of a metal that can be alloyed with yttrium and a carbon anode, and reduces the produced yttrium. When depositing on the cathode and alloying with the metal constituting the cathode to form a predetermined yttrium alloy, yttrium fluoride is used as the yttrium compound, and the molten salt electrolytic bath contains the yttrium compound. is substantially 20-93% by weight of yttrium fluoride, 7-80% by weight of lithium fluoride,
while being adjusted to consist of up to 40% by weight barium fluoride and up to 20% by weight calcium fluoride;
The yttrium alloy is formed in a liquid state on the cathode, and the yttrium alloy in the liquid state is dropped as droplets into a receiver having an opening in an electrolytic bath below the cathode, and is collected as a liquid layer. Furthermore, the target yttrium alloy was taken out in a liquid state from the liquid layer in the receiver.

Thus, according to the present invention, yttrium alloys such as yttrium-nickel alloys, yttrium-iron alloys, etc. can be produced in a single step of the electrolytic reduction operation, and such alloys can be used to improve the material properties of the metal materials to which they are added. Yttrium alloys with a low content of impurities and inclusions that have adverse effects and a high yttrium content can now be produced economically, on a large scale, and continuously in one step. More specifically, since a solid cathode is used, the cathode is not only easy to handle, but also the produced alloy can be taken out as a liquid alloy during electrolysis, so electrolysis can be carried out without interrupting the electrolysis. Continuous operation is possible, and low-temperature operation, which is an advantage of the consumable cathode method, can be carried out continuously.
The electrolytic performance and the quality of the produced alloy are effectively improved.

Furthermore, according to the present invention, it is possible to achieve large-scale and continuous operation, which is difficult to achieve with the above-mentioned reduction method using active metals such as calcium, and to suppress the contamination of impurities such as active metals. It has become possible to avoid all difficulties in continuous operation in the electrolytic production method of the fluoride-oxide mixed molten salt used as the raw material.

Furthermore, according to the present invention, it is possible to operate at a lower temperature than electrolysis using yttrium dioxide as a raw material, thereby effectively suppressing the contamination of impurities and inclusions from furnace materials etc. into the produced alloy. In addition, since the anode current density can be increased at the same temperature, when using an anode of the same size, the current can be increased compared to the electrolytic method using the oxide as a raw material. This has the advantage of improving productivity.

In the present invention, the cathode may be a metal constituting the target ia)ium alloy, such as nickel,
A metal that can be easily alloyed such as iron, copper, cobalt, manganese, chromium, titanium, etc. will be used.

In addition, in such a method of the present invention, the molten salt electrolytic bath is, for example,
It is desirable that the electrolytic reduction operation be carried out at a temperature of 10° C. to 1000° C., or 910° C. to 1000° C. in the case of yttrium-iron alloy electrolysis, and in the electrolytic reduction operation. is anode current density: 0.05-4. OA/cj, cathode current density: Conditions of 0.50 to 80 A/ad are preferably employed.

Furthermore, if the molten salt electrolytic bath containing the fluoride raw material in which the electrolytic reduction operation is carried out is substantially composed of a binary system of yttrium fluoride and lithium fluoride, At least 25% by weight of yttrium fluoride and at least 15% by weight of lithium fluoride
It is desirable to adjust the amount so that it is present in the electrolytic bath in the above proportion.

In carrying out the present invention, (a) a molten salt electrolytic bath consisting essentially of yttrium fluoride and lithium fluoride, and barium fluoride and calcium fluoride added as necessary; , an electrolytic cell made of a refractory material, (b) a lining applied to the inner surface of the electrolytic cell in contact with the bath, and (c) inserted and immersed in the molten salt electrolytic bath of the electrolytic cell. (d) a longitudinal carbon anode with substantially no change in shape in the longitudinal direction; (e) an elongated cathode made of a metal capable of alloying with yttrium; (e) disposed in the molten salt electrolytic bath of the electrolytic cell, with an opening located below the cathode, and with the carbon anode; droplets of yttrium alloy produced on the cathode by electrolytic reduction of yttrium fluoride by a direct current applied between the cathode and the cathode;
an alloy receiver for collecting the generated alloy droplets; (f) a liquid alloy take-out means for taking out the liquid yttrium alloy in the alloy receiver to the outside of the electrolytic cell; According to its consumption as the alloy is formed,
A device including a cathode insertion means for inserting the cathode into the molten salt electrolytic bath of the electrolytic cell so as to obtain a predetermined current density is preferably used.

However, such an apparatus for producing yttrium alloy further includes an anode insertion means for inserting the carbon anode into the molten salt electrolytic bath of the electrolytic tank so as to obtain a predetermined current density, and fluorine as a raw material. It is desirable to have a raw material supply means for supplying yttrium chloride into the electrolytic cell, and as the lining applied to the inner surface of the electrolytic cell, instead of a refractory metal material such as molybdenum or tungsten, A material made of an inexpensive cathode metal is preferably used.

Further, in the present invention, in order to effectively take out the liquid yttrium alloy collected in the alloy receiver disposed in the electrolytic cell out of the electrolytic cell while keeping the liquid state, the liquid alloy The extraction means is configured to have a pipe-shaped nozzle inserted into the liquid produced alloy in the alloy receiver, and through the nozzle, sucks up the produced alloy by vacuum suction and takes it out of the electrolytic cell. What you can do is
It will be advantageously adopted from the viewpoint of industrial implementation.

(Specific explanation of the configuration) First, FIG. 1 shows a schematic diagram of an electrolytic system for carrying out the present invention. is adapted to be charged with a solvent 4 constituting a molten salt electrolytic bath.

The solvent 4 is yttrium fluoride (Y
F3> and lithium fluoride (L i F) are used, but in addition to these, barium fluoride (BaFz) and calcium fluoride (CaFz) can be used alone or in combination. On the other hand, the electrolytic raw material is supplied from the raw material supply device 6 into the electrolytic bath in the electrolytic cell 2, but in the present invention, this raw material is not yttrium oxide (Yto), but is used in the composition of the electrolytic bath. Yttrium fluoride, which is one of the ingredients, is used.

Further, a carbon anode 8 and a cathode 10 made of an alloyed metal such as nickel or iron are respectively immersed in the electrolytic bath in the electrolytic bath 2, and between the anode 8 and the cathode 10, a DC power 12 is provided. By applying , electrolytic reduction of yttrium fluoride in the electrolytic bath is performed. The metallic yttrium deposited on the cathode 10 by this electrolytic reduction immediately forms a liquid alloy with metals such as nickel or iron constituting the cathode 10, drips from the surface of the cathode 10, and enters the electrolytic cell 2. It will accumulate in a receiver placed in the electrolytic bath. Note that at the temperature at which the above-mentioned predetermined solvent composition melts, the alloy formed on the cathode 10 is in a liquid state, and the specific gravity of the electrolytic bath made of such a molten salt is lower than that of the formed alloy. Since the liquid alloy is also made smaller, as the liquid alloy is formed on the cathode 10, it falls below the surface of the cathode 10.

Therefore, the liquid alloy collected in a receiver having an opening located below the cathode 10, which receives the liquid alloy falling from the cathode 10, is further taken out to the outside of the electrolytic cell 2 by a suitable alloy removal means 14. , and will be collected.

In addition, the electrolytic bath, the produced alloy, and the electrode (anode 8
A protective gas 16 is introduced in order to prevent deterioration of the cathode 10), the constituent materials of the electrolytic cell, etc., and to avoid the mixing of harmful impurities and inclusions into the produced alloy. Further, the gas generated in the electrolytic cell 2 during the electrolytic reduction operation is led to the waste gas treatment device 18 together with the introduced protective gas, and is subjected to a predetermined treatment.

By the way, in the electrolysis system according to the present invention, as described above, yttrium fluoride is used as the electrolytic raw material, unlike yttrium oxide. When using yttrium fluoride as a raw material, since yttrium fluoride itself is the main component of the electrolytic bath, it is easy to supplement the amount consumed by electrolysis by supplying it, and oxide electrolysis Electrolysis can be continued in a warmer electrolytic bath over a wider range of raw material concentrations than in the case of . As for the supply method of this raw material yttrium fluoride, it is common to add it to the surface of the electrolytic bath in the form of a powder, which is preferable because it dissolves quickly in the electrolytic bath. or a method of immersing a powder compact in an electrolytic bath.
It is possible to do so. Furthermore, compared to the case of electrolysis of yttrium oxide6, in the electrolysis operation of yttrium fluoride, the permissible range of the concentration of the electrolytic raw material in the electrolytic region between the electrodes is warmly large, and therefore the movement of the supplied raw material to this region is Even if there is a slight delay in the process, it will not interfere with the continuation of electrolysis, and therefore, regarding the supply position of the raw material yttrium fluoride and the supply amount of electrolytic electricity,
It has the advantage that it can be selected more freely without being subject to detailed restrictions as in the case of using yttrium oxide as a raw material.

In addition, in the present invention, in order to produce a yttrium alloy with few impurities, it is necessary to lower the electrolysis temperature,
For this purpose, substantially 20 to 93% (by weight, the same applies hereinafter) of indium fluoride, 7 to 80% of lithium fluoride, up to 40% of barium fluoride, and up to 20% of calcium fluoride. A mixed molten salt composed of substantially only fluoride is selected as the electrolytic bath, and even if the above-mentioned raw material yttrium fluoride is added to such an electrolytic bath, the is always adjusted so that the electrolytic bath has such a composition range.

In addition, if the concentration of yttrium fluoride in the electrolytic bath composition according to the present invention is less than the lower limit, that is, less than 20%, the electrolytic performance will deteriorate, and the upper limit concentration (93%)
If it exceeds this, problems such as the melting point of the electrolytic bath becoming too high will occur.

In addition, if the concentration of lithium fluoride is too low, the melting point of the electrolytic bath will rise too much, while if the concentration is too high, the reaction with the formed alloy will be intense.
Since it causes problems such as deterioration of electrolytic performance, its concentration needs to be adjusted to 7 to 80%.

Furthermore, barium fluoride and calcium fluoride are added for the purpose of reducing the amount of expensive lithium fluoride used and adjusting the melting temperature of the mixed molten salt that is formed. If there is too much fluoride, the melting point of the electrolytic bath will rise too much, so the former barium fluoride should be used at a proportion of up to 40%, and the latter calcium fluoride at a proportion of up to 20%, each alone or together. It will be used. The total amount of these four components, namely yttrium fluoride, lithium fluoride, barium fluoride and calcium fluoride, is substantially 100%.
%, an electrolytic bath is formed.

However, regarding such an electrolytic bath composition, if the electrolytic bath is a binary system consisting of only two components, yttrium fluoride and lithium fluoride, yttrium fluoride should account for at least 25% of the electrolytic bath. As mentioned above, it is desirable to adjust the amount of lithium fluoride so that it exists in a small amount (at least 15%). Each fluoride used as a component of this electrolytic bath is important for the electrolytic operation and the product properties of the final use of the produced alloy. It does not necessarily have to be of high purity as long as it does not contain impurities that have an adverse effect on the electrolytic bath.Usually, impurities that are unavoidable in industrial raw materials are included in the electrolytic bath as long as they are tolerable. The composition of the electrolytic bath is selected so that the electrolytic bath has a specific gravity smaller than the specific gravity of the yttrium-nickel alloy, yttrium-iron alloy, etc. to be produced. Sometimes, the produced yttrium-nickel alloy, yttrium-iron alloy, etc. may fall from the cathode into the electrolytic bath due to the difference in specific gravity, and easily reach a receiver for the produced alloy, which has an opening located below the cathode. It is.

In the present invention, the temperature during electrolysis of the electrolytic bath having such a composition is appropriately selected depending on the type of yttrium alloy to be produced. For example, in the case of yttrium-iron alloy electrolysis, the temperature is
In the case of yttrium-nickel alloy electrolysis, the temperature is suitably adjusted to a range of 0 to 1000°C, and 810 to 1000°C. As mentioned above, if the electrolytic bath temperature becomes too high, impurities and inclusions will be mixed into the produced alloy, and if the electrolytic bath temperature is too low,
For example, in yttrium-iron alloy electrolysis, since the eutectic temperature of the yttrium-iron binary alloy is approximately 900°C,
The precipitated metallic ythtrium and the iron of the cathode are not sufficiently alloyed, and due to the precipitation of solid metallic ytrium with a high melting point,
A short circuit phenomenon occurs between the cathode and the anode, making it difficult to continue electrolysis. Furthermore, in yttrium-nickel alloy electrolysis, it is difficult to form a homogeneous molten salt electrolytic bath, the properties of the electrolytic bath deteriorate, and it becomes difficult to continue electrolysis. It goes without saying that within such a temperature range, it is possible to produce a yttrium master alloy with less contamination of impurities from furnace materials etc. at the lowest possible temperature.

In this temperature range, yttrium alloys such as yttrium-nickel alloys and yttrium-iron alloys containing 50% by weight or more of yttrium and having a high yttrium concentration can be advantageously produced, and the produced alloys can be produced at this temperature. It forms a liquid layer in the receiver within the range, making it suitable for extraction in a liquid state. The liquid alloy in this receiver can be effectively taken out from the upper part of the electrolytic cell by a vacuum suction method, and can also be taken out from below by a pouring method. Moreover,
When taking this out, there is no need to specially heat the alloy in the receiver (it can be taken out of the electrolytic cell very easily as a liquid alloy).

In addition, in the present invention, as the electrode for electrolysis, the cathode is a metal that can be easily alloyed such as nickel or iron, the anode is carbon,
Graphite is particularly preferably used. If metals such as nickel and iron for the cathode contain impurities, they will be directly introduced into the formed alloy, so it is preferable to use a metal material with low impurities as necessary as the metal material for the cathode. . Further, according to the present invention, as the electrolytic operation progresses, the alloyed metal such as nickel and iron constituting the cathode produces the desired yttrium alloy such as yttrium-nickel alloy, yttrium-iron alloy, etc. However, if the metals such as nickel and iron that are consumed by such electrolysis are replenished and the cathode is sequentially immersed in the electrolytic bath, the intended purpose can be achieved without interrupting the electrolytic operation. This makes it possible to continuously produce yttrium alloys. At this time, it is of course possible to thread the ends of the metal members of the cathode and connect the metal members constituting the cathode one after another by threaded connections or the like to compensate for the consumed cathode portion.

Thus, the ability to use solid alloyed metals as cathodes, compared to the use of molten metals as cathodes,
Since it is easy to handle and the electrolytic furnace can be simplified in terms of equipment, it has a great advantage in industrialization in that it is easy to increase the size of the electrolytic furnace.

Furthermore, in the electrolysis of yttrium fluoride using the carbon anode according to the present invention, the current density over the entire surface of the anode is constantly maintained within the range of 0.05 to 4° OA/ad during the electrolysis operation. It is desirable to be present. However, if this current density is too low, the anode surface area will be too large or the current per unit surface area of the anode will be too small, resulting in poor productivity and no industrial advantage. Furthermore, if the current density becomes too high, an anode effect or similar abnormal phenomena when yttrium oxide is used as a raw material tend to occur.

Therefore, in the present invention, it is recommended that the anode current density, which is one of the electrolytic conditions, be maintained within the above range to effectively avoid the occurrence of such abnormal phenomena. Note that, taking into account local variations on the anode surface, the current density over the entire anode surface is between 0.1 and 3.0 A/cn! It is more preferable to hold it between. Furthermore, when using yttrium fluoride as a raw material, compared to when using yttrium oxide as a raw material,
At the same temperature, the anode current density can be increased, which is preferable from the point of view of actual operation.

On the other hand, the current density of the cathode is allowed over a wide range of 0.50 to 80 A/cal as the current density over the entire surface of the cathode. However, if the cathode current density is too low, the current per unit surface area of the cathode is too small.
Productivity deteriorates and it becomes unindustrial. Furthermore, if this cathode current density becomes too high, the electrolytic voltage will increase significantly and the electrolytic results will deteriorate. In addition, when continuing the actual electrolytic operation, it is recommended to keep the cathode current density within a narrower range of 1.0 to 30 A/cJ in order to maintain a narrow fluctuation range of the electrolytic voltage and facilitate the electrolytic operation. , can be said to be more preferable.

Furthermore, according to the present invention, carbon, which is different from the bath-resistant material of the electrolytic bath, is used as the anode, unlike the case where the bath-resistant container (bath-resistant material) of the electrolytic bath also serves as the anode. ,
There is no need to terminate the electrolysis due to consumption of the anode; it is only necessary to compensate for the consumption and further immerse the anode in the electrolytic bath, or, since a plurality of anodes are used, to replace them with new anodes one by one. Similarly, the cathode only needs to be immersed in an electrolytic bath to compensate for its consumption, or replaced with a new cathode. In the present invention, due to the large difference in the surface current density ratio between the anode and cathode, it is preferable to use an electrode arrangement in which a plurality of anodes are arranged around each cathode so that the anode faces the cathode. In such cases, if the anodes are replaced sequentially, it is possible to continuously produce the desired yttrium alloy without interrupting the electrolytic operation. Therefore, the advantages of electrolytic method can be fully utilized. Moreover, since both the anode shape and the cathode shape can be used with an external shape that does not substantially change in the length direction, there will be no inconvenience caused in their continuous use. be.

A preferred example of the structure of an electrolytic cell implementing the present invention is schematically shown in FIG.

In FIG. 2, the electrolytic cell 20 is composed of a lower tank 22 and a lid 24 that covers the opening thereof. The outer sides of the lower tank 22 and the lid body 24 are usually constructed of tank outer frames 26 and 28 made of metal such as steel.

Further, the lower tank 22 and the lid body 24 each have fire-resistant insulation layers 30 and 32 made of brick, castable alumina, etc. on the outside, and bath-resistant material layers 34 and 36 made of graphite, carbonaceous stamp material, etc. on the inside. Arranged and configured.

A lining material 38 is provided on the inner bath-contact surface of the inner bath-resistant material layer 34 of the lower tank 22 to cover the bath-contact surface. This lining material 38 is a bath-resistant material layer 34.
In addition to preventing the contamination of impurities from metals such as tungsten and molybdenum, if the metal is made of refractory metals such as tungsten and molybdenum, it also serves as a receiver for the liquid yttrium alloys such as yttrium-nickel alloys and yttrium-iron alloys. You can also do that. However, in the present invention, such lining material 3
8, it is recommended to use metal materials compatible with the produced alloys, such as iron and nickel, which are cheaper than refractory metals. Furthermore, the bath-resistant material layer 34 is not necessarily necessary (although there is no problem in applying the lining material 38 directly on the fire-resistant heat insulating material layer 30).

Further, one or more nickel, iron, copper, cobalt, manganese, chromium,
A cathode 40 made of a metal that can be easily alloyed such as titanium, and a plurality of carbon anodes 42 arranged opposite to this cathode 40 are provided. The electrode is immersed in an electrolytic bath 44 containing the predetermined molten salt over a length that provides a predetermined current density. Here, two carbon anodes 42, 42 are shown among the anodes disposed facing the cathode 40, and graphite is suitably used as the material for them.

Further, these carbon anodes 42, 42 are used in the form of rods, plates, tubes, etc., and in order to increase the anode surface area of the part immersed in the electrolytic bath 44 and lower the anode current density, grooves are formed as known in the art. It can also be attached. In addition, in FIG. 2, the carbon anode 42 has a slight slope at the anode immersion part, showing traces of anode wear due to electrolysis. There is no problem even if an electric lead made of a suitable conductor such as metal is attached to the anode 42 for power supply. Also,
The anode 42 can be moved up and down by an anode lifting mechanism 46 serving as an anode insertion means, and can be moved intermittently or continuously to ensure an appropriate anode current density for continuing electrolysis. Moreover, the surface area of the immersion part can be adjusted by adjusting the immersion depth. Note that the anode lifting/lowering mechanism 46° 46 can also have the function of electrically connecting to the anode.

On the other hand, the cathode 40 is made of a metal such as nickel or iron to be alloyed with metallic yttrium deposited by electrolytic reduction, one of which is shown here. Further, in FIG. 2, the cathode immersion portion is shown in a conical shape to show traces of cathode consumption due to the formation of droplets of yttrium alloy. Since the electrolysis temperature is selected to be below the melting point of the metal material of the cathode 40, the cathode 40 is solid and is used in the form of a wire, rod, plate, tube, or the like. The cathode 40 is also continuously or intermittently fed into the electrolytic bath 44 by a cathode lifting mechanism 48 serving as a cathode insertion means to compensate for bone loss due to alloy formation. This cathode lifting mechanism 48 is
It can also serve as an electrical connection to the cathode. Furthermore, there is no problem if the surface of the cathode 40 other than the immersed part is protected with a suitable protective sleeve or the like for corrosion prevention.

Further, a produced alloy receiver 50 is placed on the bottom of the lower tank 22 in the electrolytic bath 44 so that the receiver opening is located below the cathode 40, and the produced alloy receiver 50 is placed above the cathode 40 by electrolytic reduction operation. Liquid yttrium produced in
Yttrium alloy 52, such as a nickel alloy or indium-iron alloy, drips from the cathode surface and is collected in a produced alloy receiver 50 that opens just below. The produced alloy receiver 50 is formed using a refractory metal that has low reactivity with the produced alloy 52, such as tungsten, tantalum, molybdenum, niobium, or an alloy thereof, or a boron such as boron nitride. Ceramics such as compounds and oxides,
Alternatively, it can also be formed using a material such as cermet, or iron or nickel.

The electrolytic bath 44 is made of a fluoride mixed molten salt containing yttrium fluoride, whose composition is adjusted to the composition according to the present invention, and whose specific gravity is equal to or lower than the specific gravity of the yttrium alloy to be produced. chosen to be. The electrolytic raw material consumed by electrolysis is supplied from a raw material supply device 54 through a raw material supply hole 56 provided in the lid 24, so that the electrolytic bath 44 of a predetermined composition is maintained.

Furthermore, when a predetermined amount of generated alloy 52 drips from the cathode 40 and accumulates in the receiver 50, it is taken out of the electrolytic cell 20 in a liquid state by a predetermined alloy recovery mechanism (retrieval means). However, in the present invention, as shown in FIG.
8 is inserted into the electrolytic bath 44 through the produced alloy suction hole 60 provided in the lid body 24, and the tip of the nozzle 58 is immersed in the produced alloy 52 in the produced alloy receiver 50. Advantageously, a means for sucking up the generated alloy 52 and taking it out of the electrolytic cell 20 by suction using the vacuum suction effect of the electrolytic cell 20 is advantageously employed.

However, instead of using such a vacuum suction method to take out the produced alloy 52, an extraction pipe is provided that penetrates the lower part of the electrolytic cell 20 (lower tank 22), and the tip of this extraction pipe is further connected to the produced alloy receiver 50. It is also possible to adopt an alloy recovery mechanism in which the formed alloy 52 is flowed out of the furnace and downward through the take-out pipe by penetrating the pipe and opening into the receiver 50.

Although not shown, a protective gas is supplied into the electrolytic furnace 20, and the gas generated by the electrolytic operation is discharged to the outside through the waste gas outlet 62 together with the protective gas. It is designed to be ejected. Further, although such an electrolytic cell 20 is not provided with a special heating device for maintaining the electrolysis temperature described above, in order to maintain the electrolysis temperature at a predetermined temperature, the inside of this electrolytic cell 20 may be heated as necessary. It goes without saying that a suitable heating device may be provided inside or outside the heating device.

(Examples) In order to clarify the present invention more specifically, some examples according to the present invention will be shown below, but the present invention shall be interpreted in an equivalent and restrictive manner by the description of such examples. It goes without saying that this is not the case.

It should be noted that the present invention can be implemented in various embodiments in addition to the above-described detailed description of the present invention and the following examples, and as long as they do not depart from the spirit of the present invention,
It should be understood that any of the various embodiments that can be implemented based on the knowledge of those skilled in the art belong to the scope of the present invention.

Example 1 0.76 kg of a rare earth metal-iron (RE-Ni) alloy having an average composition of 75% rare earth metal (based on weight, the same applies hereinafter), mainly yttrium, and 25% nickel,
It was obtained as follows.

That is, in an apparatus having a configuration similar to the electrolytic cell shown in Fig. 2, a graphite crucible lined with nickel is used as the bath-resistant material of the electrolytic cell, and a molybdenum crucible is installed at the center of the bottom of the graphite crucible as a receptacle for the produced alloy. Using a container, an electrolytic bath consisting of a binary fluoride mixed molten salt consisting essentially of yttrium fluoride and lithium fluoride was electrolyzed in an inert gas atmosphere at an average electrolysis temperature of 840°C. As a cathode, a single 6-inch electrode was immersed in the electrolytic bath in the center of the graphite crucible.
A nickel wire of 40 mm diameter was used as an anode, and four graphite rods of 40 mm diameter were arranged concentrically around the cathode (in planar form) and immersed in the electrolytic bath.

Using yttrium fluoride as a raw material, electrolysis was carried out for 16 hours while continuously supplying the powder to the electrolytic bath while maintaining the electrolytic conditions within the range shown in Table 1 below.

During this period, electrolysis operations were able to continue extremely well.
A liquid rare earth metal (yttrium)-nickel alloy was dripped in sequence and collected in a molybdenum receiver placed in the electrolytic bath. This accumulated alloy is released every 8 hours.
The alloy was taken out of the electrolytic furnace using a vacuum suction type alloy recovery device equipped with a vacuum suction nozzle.

The electrolytic results obtained by such electrolytic operation and the analysis results of the produced alloy are shown in Tables 1 and 2 below. Note that the current efficiency was determined based on the weight of the rare earth metal recovered (all assumed to be yttrium).

Example 2 0.73 kg of a rare earth metal (yttrium)-iron alloy having an average composition of 73% rare earth metal and 27% iron consisting essentially of yttrium was obtained by the following electrolytic operation.

First, a graphite crucible lined with iron as a bath-resistant material was used as a container for the electrolytic bath, and a molybdenum container placed in the center of the bottom of the crucible was used as a receiver for the produced alloy. An electrolytic bath consisting of a binary fluoride mixed molten salt containing only yttrium and lithium fluoride was electrolyzed in an inert gas atmosphere at an average electrolysis temperature of 942°C. As the cathode, one iron rod with a diameter of 6 squares and arranged in the same manner as in Example 1 was used, and as the anode, four graphite rods with a diameter of 40 squares as in Example 1 were used as the anodes.

Then, when yttrium fluoride was used as a raw material and was continuously supplied to the electrolytic bath while maintaining the electrolytic conditions within the range shown in Table 1 below, over a period of 16 hours,
Good electrolysis operations continued.

In addition, a liquid rare earth metal (yttrium)-iron alloy was sequentially dropped and collected in a molybdenum receiver. Furthermore, the collected alloy produced in the receiver could be taken out in a liquid state as in Example 1.

The electrolytic results obtained by such electrolytic operation and the analysis results of the produced alloy are shown in Tables 1 and 2 below, respectively.

Table 1 Table 2 As is clear from the results in Tables 1 and 2, by electrolyzing yttrium fluoride according to the present invention, yttrium-nickel alloys or yttrium-iron alloys with high yttrium content can be produced at once. It is recognized that the resulting alloy is a yttrium-nickel alloy or a yttrium-iron alloy with a low content of impurities that degrade the alloy properties.

Note that the numerical values of the alloy-containing components in Table 2 are the average values of the analysis values of the alloy taken out every 8 hours.

In addition, in the above examples, it is easy to conduct electrolysis by mu for a longer period of time, and even in such a case, it has been confirmed that the same results as in each example can be obtained. .

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a specific electrolytic system for implementing the present invention, and FIG. 2 is a sectional view showing an example of the structure of an electrolytic cell for implementing the present invention. 2: Electrolytic cell 4: Solvent 6: Raw material supply device 8: Carbon anode 10: Cathode 12: Electric power 14: Alloy extraction means 16: Protective gas 18: Waste gas treatment device 20: Electrolytic cell 22: Lower tank 24: Lid body 30 .32: Fireproof insulation layer 34. 36: Bath-resistant layer 38 lining material 40: Cathode 42: Carbon anode 44: Electrolytic bath 46: Anode lifting mechanism 48: Cathode lifting mechanism 50: Generated alloy receiver 52: Generated alloy 54: Raw material supply device 58: Vacuum suction nozzle 60: Produced alloy suction hole Applicant: Sumitomo Light Metal Industries, Ltd. Figure 1, Figure 2, et al. 8

Claims (16)

[Claims] (1) Using a solid cathode made of a metal that can be alloyed with yttrium and a carbon anode, a yttrium compound is electrolytically reduced in a molten salt electrolytic bath, and the produced yttrium is deposited on the cathode, and the cathode is A method of forming a predetermined yttrium alloy by alloying with constituent metals, wherein yttrium fluoride is used as the yttrium compound, and the molten salt electrolytic bath containing the yttrium compound has a weight of substantially 20 to 93%. % yttrium fluoride, 7-80% lithium fluoride, 40% by weight
The yttrium alloy is formed in a liquid state on the cathode, and the yttrium alloy in the liquid state is deposited in droplets. The yttrium alloy is dropped into a receiver having an opening in the electrolytic bath below the cathode and collected as a liquid layer, and the yttrium alloy is taken out in a liquid state from the liquid layer in the receiver. A method for producing yttrium alloy. (2) The manufacturing method according to claim 1, wherein the cathode is made of nickel and a yttrium-nickel alloy is manufactured. (3) The manufacturing method according to claim 1, wherein the cathode is made of iron and a yttrium-iron alloy is manufactured. (4) The manufacturing method according to claim 2, wherein the molten salt electrolytic bath is maintained at a temperature of 810 to 1000°C, and the electrolytic reduction operation is allowed to proceed at this temperature. (5) The manufacturing method according to claim 3, wherein the molten salt electrolytic bath is maintained at a temperature of 910 to 1000°C, and the electrolytic reduction operation is performed at this temperature. (6) The electrolytic reduction operation has an anode current density of 0.05 to
4.0A/cm^2, cathode current density: 0.50-80A
The manufacturing method according to any one of claims 1 to 5, which is carried out under conditions of /cm^2. (7) The manufacturing method according to any one of claims 1 to 6, wherein the carbon anode is a graphite electrode. (8) The molten salt electrolytic bath containing the yttrium compound is
Claims that are substantially composed of yttrium fluoride and lithium fluoride, and are adjusted so that the yttrium fluoride is present in an amount of at least 25% by weight, and the lithium fluoride is present in an amount of at least 15% by weight, respectively. The manufacturing method according to any one of items 1 to 7. (9) An electrolytic cell made of a refractory material and containing a molten salt electrolytic bath consisting essentially of yttrium fluoride and lithium fluoride, as well as barium fluoride and calcium fluoride added as necessary. , a lining provided on the inner surface of the electrolytic cell in contact with the bath; a longitudinal carbon anode that is inserted into and immersed in the molten salt electrolytic bath of the electrolytic cell and whose shape does not substantially change in the longitudinal direction; , an elongated cathode made of a metal capable of alloying with yttrium and having substantially no change in shape in the length direction and inserted into and immersed in the molten salt electrolytic bath of the electrolytic cell; yttrium produced on the cathode by electrolytic reduction of yttrium fluoride by a direct current applied between the carbon anode and the cathode; an alloy receiver for collecting the yttrium alloy droplets, into which the alloy droplets are dropped; a liquid alloy take-out means for taking out the liquid yttrium alloy in the alloy receiver to the outside of the electrolytic cell; and the cathode. and a cathode insertion means for inserting the yttrium alloy into the molten salt electrolytic bath of the electrolytic cell so as to obtain a predetermined current density according to its consumption as the yttrium alloy is produced. Yttrium alloy manufacturing equipment. (10) The manufacturing apparatus according to claim 9, wherein the cathode is made of nickel. (11) The manufacturing apparatus according to claim 9, wherein the cathode is made of iron. (12) Any one of claims 9 to 11, further comprising an anode insertion means for inserting the carbon anode into the molten salt electrolytic bath of the electrolyzer so as to obtain a predetermined current density. The manufacturing equipment described in . (13) Claim 9, comprising a raw material supply means for supplying yttrium fluoride as a raw material into the electrolytic cell.
13. The manufacturing apparatus according to any one of Items 1 to 12. (14) The liquid alloy extraction means has a pipe-shaped nozzle inserted into the liquid yttrium alloy in the alloy receiver, and sucks up the yttrium alloy by vacuum suction through the nozzle and takes it out of the electrolytic cell. A manufacturing apparatus according to any one of claims 9 to 13. (15) The manufacturing apparatus according to any one of claims 9 to 14, wherein the lining is made of a nickel material or an iron material. (16) The manufacturing apparatus according to any one of claims 9 to 15, wherein the carbon anode is a graphite electrode.