JP2012132033A - Melted salt electrolytic cell and refining method of low melting point metal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a melted salt electrolytic refining device by which operation is easy, feeding and pulling of an alloy containing a low melting point metal are easy, deterioration in a melted salt can be suppressed for a long time and purity of the useful low melting point metal can be heightened and to provide a refining method of the low melting point metal.SOLUTION: The melted salt electrolytic cell refining and recovering the low melting point metal includes at least an anode chamber 1, a space storing a liquid material of the alloy containing the low melting point metal, an inner cylinder 2 disposed so as to come in contact with a bottom part of the anode chamber, a cathode chamber 8 disposed in the inner part of the inner cylinder and a DC power source generator 13 externally attached to the anode chamber. The useful low melting point metal can be obtained by electrolytic refining using the melted salt electrolytic cell.

Description

  The present invention relates to a molten salt electrolytic cell for purifying and recovering a useful low melting point metal from an alloy containing indium, tin, gallium and the like, which are low melting point metals, and a method for purifying the low melting point metal.

  The molten salt electrolysis method has long been studied as a method for purifying base metals such as sodium, magnesium, and aluminum, which are difficult to be electrolytically deposited by ordinary aqueous electrolysis, and has many practical examples. Further, many studies have been made on the method of electrolytically depositing a refined molten metal on a cathode using an alloy containing a metal having a relatively low melting point, and the results have been disclosed. A problem common to these molten salt electrolysis methods is to provide an electrolytic cell structure capable of avoiding contact with the atmosphere during operation because the molten salt has a remarkable hygroscopic property.

  For example, metal indium, which is a kind of low melting point metal, can be recovered from an alloy containing metal indium by electrolytic purification using a molten salt as an electrolyte, and its electrolytic cell structure and purification method are disclosed (for example, Patent Documents). 1). The electrolytic cell has a structure in which a crucible which is an anode chamber is arranged in the center of the cathode chamber, an alloy containing metal indium is held in the crucible, and the purified metal indium is electrolytically deposited on the outer periphery of the crucible. It is. Certainly, metal indium can be recovered by this electrolytic cell. However, in the anode chamber disposed in the center, impurity components such as tin are concentrated as the electrolysis progresses, so that the operation of taking out the crucible is essential. This stopped the operation and worked in a high temperature state where the molten salt did not solidify, so that the molten salt contacted the atmosphere, absorbed moisture and deteriorated, and stable operation for a long period of time was not possible.

  As another electrolytic cell, an electrolytic cell is disclosed in which a cathode is disposed at the bottom, a layer of a molten salt bath is retained on the cathode, and an anode is retained in a porous container on the cathode (for example, , See Patent Document 2). Certainly, this electrolytic cell enables electrolytic deposition of useful components such as metal indium from the alloy. However, since a special porous body that is not used in an ordinary electrolytic cell is required, the equipment cost is high, and it was necessary to pay close attention so that the porous body was not damaged even during operation. In addition, the anode held in the container made of the porous body may leak from the pores of the porous body, the anode and the cathode may be short-circuited, and the operation may have to be stopped. Furthermore, although related to the strength of the porous body, there is a problem that it is difficult to scale up.

WO2006-046800 JP-A-57-207185

  An object of the present invention is to provide an effective and efficient molten salt electrolytic cell that can solve the problems of the conventional method, that is, an operation including supply and extraction of an alloy containing a low-melting-point metal is easy. By avoiding contact with the atmosphere, the molten salt electrolytic cell can suppress the deterioration of the molten salt over a long period of time and can increase the purity of useful low-melting point metals without using a special porous material. Another object of the present invention is to provide a method for purifying a low melting point metal.

  As a result of intensive studies on a technique for electrolytically depositing a useful low-melting-point metal on the cathode from an alloy containing a low-melting-point metal and purifying and recovering it, the electrolytic cell structure used for molten salt electrolytic purification is optimized. Thus, it is found that the operation is easy, the supply and extraction of the alloy containing the low melting point metal is easy, the purity of the useful low melting point metal is increased, and the deterioration of the molten salt can be suppressed over a long period of time, The present invention has been completed.

That is, the present invention is a molten salt electrolytic cell for purifying and recovering a low melting point metal,
An anode chamber containing an alloy liquid containing the low-melting-point metal and having an opening into which an anode conductor can be inserted;
An inner cylinder for holding the molten salt layer of the low-melting-point metal halide on the contained liquid material, and allowing the liquid material to communicate in the anode chamber without causing the molten salt layer to flow outside;
It has an inlet and an outlet for the low-melting-point metal after purification, and is arranged so that the inlet is located in the molten salt layer. A cathode conductor can be inserted, and the inside is the low-melting-point metal. A molten salt electrolysis cell comprising a filled cathode chamber, and a method for purifying a low melting point metal using the molten salt electrolysis cell.

  Hereinafter, an example of the molten salt electrolytic cell of the present invention will be described with reference to FIGS. 1 and 2, but the molten salt electrolytic cell described below is only one aspect of the present invention. It is not limited to the contents of.

  As shown in FIG. 1, a molten salt electrolytic cell 100 according to the present invention includes an anode chamber 1, an inner cylinder 2, and a cathode chamber 8. The anode chamber 1 is an open container for containing a liquid material (anolyte 9) of an alloy containing a low melting point metal. The inner cylinder 2 is disposed in the container so that an end surface having an opening faces the bottom surface inside the anode chamber 1. The wall surface of the inner cylinder 2 and the surface opposite to the end surface having the opening cover part of the liquid alloy material (anolyte 9) containing the low melting point metal housed in the anode chamber 1. The cathode chamber 8 has an inlet 3 for introducing a low-melting point metal and an outlet 7 for leading out the low-melting point metal. The inlet 3 is arranged inside the inner cylinder 2 and leads out the low-melting point metal. The outlet 7 is disposed outside the inner cylinder 2. The interior of the cathode chamber 8 is filled with a low melting point metal (catholyte 11). The molten salt electrolyzer may be disposed on the heater 12 and may be electrolyzed while being heated by the heater 12 from the lower part of the anode chamber 1.

  The anode chamber 1 is a container for holding a liquid material (anolyte 9) of an alloy containing a low-melting-point metal. In the space formed by the anode chamber 1 and the inner cylinder 2, the anolyte 9 is charged and used for the anode. The conducting wire 14 can be inserted. If the electrolysis operation is continued for a long time, the unelectrolyzed components constituting the alloy are concentrated in the anode chamber 1, so that the alloy after purification from the opening is kept in order to keep the composition of the anolyte 9 constant. That is, the used anolyte 9 can be derived. In order to derive the refined alloy, the anode chamber 1 may be provided with a separate outlet. The lead-out port may be disposed in a gap between the anode chamber 1 and the inner cylinder 2. An extraction nozzle 4 may be formed at the outlet, and it is more preferable to extract the refined alloy intermittently or continuously. When the extraction nozzle 4 is opened when the content of the low melting point metal contained in the anolyte 9 is 30% by weight or less, and preferably 50% by weight or less, the purity of the low melting point metal is obtained. Can do. The supply of the anolyte 9 may be continuous or intermittent, and the supply location of the alloy may be from the gap between the anode chamber 1 and the inner cylinder 2 or a separate supply unit may be provided.

  The material of the anode chamber 1 is not particularly limited as long as it does not react with the held alloy. Preferable are graphite and metal materials that are hardly damaged, and specifically, stainless steel, nickel-base alloy, iron, iron-base alloy, titanium, and titanium-base alloy. Especially, the material comprised from 1 or more types chosen from stainless steel, iron, titanium, and graphite is preferable, and stainless steel is more preferable from the surface of corrosion resistance and economical efficiency.

  The shape of the anode chamber 1 is not particularly limited, such as a cylindrical shape, a square shape, or a polygonal shape. Preferably, it is a cylindrical type or a square type that is easy to manufacture and has high mechanical strength.

  The inner cylinder 2 is open at the bottom, and has, for example, an inert gas inlet 5 and an exhaust gas outlet 6 that can be opened and closed at the top. Since the upper part of the inner cylinder 2 is closed, the contact between the surface of the molten salt 10 and the outside air can be cut off, so that the mixing of moisture in the atmosphere, which is a cause of deterioration of the molten salt 10, can be prevented, and stable operation for a long time Is possible. Examples of the inert gas introduced into the gas phase portion in contact with the molten salt 10 include nitrogen gas and argon gas.

  The inner cylinder 2 accommodates a liquid material (anolyte 9) containing an alloy containing a low-melting point metal, and a molten salt layer 10 of a low-melting point metal halide is held on the liquid material. In order to form the molten salt layer 10 in a floating state on the top of the anolyte 9, specifically, the anolyte 9 is stored at the bottom of the inner cylinder 2, and the molten salt is supplied from the inert gas inlet 5 and the exhaust gas outlet 6. Or a powdered metal salt is put in the inner cylinder, the inner cylinder 2 is turned over on the anolyte 9, and the metal salt is melted by heating.

  Further, in order to allow the anolyte 9 to move between the inner and outer sides of the inner cylinder 2 without causing the molten salt layer 10 to flow outside, for example, a part of the lower side surface of the inner cylinder 2 has a slit shape. It is cut out. Thereby, the anolyte 9 can go back and forth between the inside and the outside of the inner cylinder 2, and the composition of the anolyte 9 can be made uniform.

  The material of the inner cylinder 2 is not particularly limited as long as it does not react with an alloy containing a molten salt and a low melting point metal held inside. From the viewpoint of price and ease of production, it is preferably composed of one or more selected from glass, ceramics and fluororesin, more preferably quartz glass and ceramics.

  The cathode chamber 8 is filled with a low melting point metal 11, and a cathode lead wire 15 can be inserted into a portion arranged outside the inner cylinder 2. The purity of the low melting point metal 11 preliminarily filled in the cathode chamber 8 before electrodeposition is preferably such that the content of the low melting point metal is 90% by weight or more.

  The inlet 3 in the cathode chamber 8 is composed of one or a plurality of containers depending on the size of the equipment. When the inlet 3 is composed of a plurality of containers, the purified low-melting-point metal liquid (catholyte 11) that is electrolytically deposited on the surface of the inlet 3 is gathered by the connected pipes, and from the outlet 7. Discharged and collected continuously or intermittently. Further, the arrangement of the introduction port 3 is not particularly limited, but as shown in FIG. 2, the oxidative dissolution of the low melting point metal from the anode alloy becomes more uniform as the introduction port 3 is uniformly dispersed in the molten salt layer 10, that is, This is preferable because the current density can be reduced. The larger the cross-sectional area of the inlet 3, that is, the area of the interface between the catholyte 11 and the molten salt 10, the larger the area that can be electrolytically deposited and the lower the electrical resistance. The cross-sectional area (the area of the molten salt 10 in FIG. 2) is reduced, so that the electrical resistance of the molten salt 10 is increased. Preferably, the cross-sectional area of the inlet 3 is 30 to 70%, more preferably 40 to 60% of the inner cylinder cross-sectional area.

  Further, it is essential that the cathode chamber 8 be formed of an insulator. Among insulators, glass, ceramics, and fluororesins that are highly corrosion resistant to molten salts and low-melting metals are preferable, and glass that is easy to manufacture, has high heat resistance, is inexpensive, and is also quartz. Glass is preferred.

  The shape of the cathode chamber 8 is not particularly limited as long as the low melting point metal can be electrolytically deposited. A cube, a rectangular parallelepiped, and a cylinder are preferable.

  Then, the purification method of the low melting metal which concerns on this embodiment is demonstrated. In the method for purifying a low melting point metal, in the molten salt electrolyzer 100, an anode chamber 1 contains an alloy containing one or more metals selected from indium, tin and gallium, and the alloy in the inner cylinder 2 A molten metal halide corresponding to the metal is held on the liquid. Then, by applying a voltage with the anode lead wire 14 and the cathode lead wire 15 inserted, molten salt electrolysis is performed, and one kind selected from purified indium, tin and gallium from the outlet 7 of the cathode chamber 8. The above metals are derived.

  By the above purification method, an alloy containing one or more metals selected from indium, tin and gallium can be purified. Among them, an alloy containing indium is suitably purified by the purification method according to this embodiment because it has a relatively low melting point and high production efficiency in molten salt electrolytic purification. The alloy refers to a metal-like substance composed of a metal element and / or a non-metal element, and the bonding state thereof is not particularly limited. The content of the low melting point metal is not particularly limited. That is, even if the low melting point metal is a main component or a trace amount is contained, it can be suitably used. From the degree of purification, recovery rate, and productivity of the low melting point metal, the content of the low melting point metal in the alloy is preferably 100 wtppm to 99.999 wt%, more preferably 1 wt% to 99.99 wt%, and even more preferably 60 wt%. 99.9 wt%.

  The type of metal other than the low melting point metal in the alloy is not particularly limited. For example, Li, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni , Cu, Zn, Ge, As, Se, Sr, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Sb, Te, Cs, Ba, Ta, W, Re, Os, Ir, Pt , Au, Tl, Pb, Bi.

  Among these, metals having good separation and purification from low melting point metals in molten salt electrolysis are Li, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni. , Cu, Zn, Ge, Sr, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Cs, Ba, Ta, W, Re, Os, Ir, Pt, Au, Tl, Pb, Bi In particular, Cu, Fe, and Ni are preferable because separation and purification are easy.

  The molten salt 10 held in the inner cylinder 2 contains a metal halide corresponding to the metal to be refined, and has a specific gravity smaller than that of an alloy containing a low melting point metal held in the anode chamber 1. There is no particular limitation as long as it is a molten salt electrolyte that can be electrolyzed. For example, a mixed molten salt of a metal halide and a zinc halide corresponding to the metal to be purified, and a mixed molten salt of a metal halide and an aluminum halide corresponding to the metal to be purified can be mentioned. More specifically, when the object to be refined is an alloy containing indium, it is preferable to use a mixed molten salt of zinc chloride and indium monochloride, a mixed molten salt of aluminum bromide and indium monobromide, or the like. it can.

  In addition, from the viewpoint of the purity of the metal to be purified, the metal halide corresponding to the metal to be purified is preferably more than 50% by weight based on the total amount of the mixed molten salt, and more than 65% by weight. It is preferable that the content be 75% by weight or more. Further, the water content in the molten salt is preferably 0.7% by weight or less, more preferably 0.5% by weight or less, and further preferably 0.4% by weight or less.

By using the molten salt electrolyzer, electrolysis can be performed at a high current density in the purification method according to the present embodiment. Current density is preferably 1~200A / dm ^2. When operating at less than 1 A / dm ² , the production rate per unit electrode area may decrease. From the viewpoint of productivity, the higher the current density, the better. However, at a current density exceeding 200 A / dm ² , when a low melting point metal useful for the cathode is electrolytically deposited, impurities may be incorporated and the purity may be lowered. The current density is more preferably ^{2 to} 150 A / dm ² , and further 3 to 100 A / dm ² .

  The operating temperature of the molten salt electrolysis is not particularly limited as long as the electrolyte bath, the alloy containing the low melting point metal, and the low melting point metal are all in a molten state. The temperature of the molten salt is preferably 50 ° C. to 400 ° C., more preferably 90 ° C. to 350 ° C., from the viewpoint of corrosion of the apparatus material and operation of molten salt electrolysis.

  In the present invention, an alloy containing a low melting point metal is used for the anode. The low melting point metal in the present invention refers to one containing at least one of indium, tin, and gallium.

  By electrolysis under the proper operating conditions described above, a high-purity low-melting point metal can be electrolytically deposited on the cathode, but when the low-melting point metal has not achieved the target purity, The molten salt electrolysis may be further performed once or more by the same operation, and refined until the target purity is reached.

  According to the molten salt electrolytic cell of the present invention, useful low-melting-point metal electrolytically deposited in the cathode chamber can be continuously recovered, and the supply and extraction of the alloy to the anode chamber can be performed without stopping the electrolysis operation. Further, it is possible to prevent moisture and oxygen gas from being mixed, which is a cause of deterioration of the molten salt. Furthermore, since the uneven current density can be prevented, the purity of the refined metal can be increased.

It is a longitudinal section showing one embodiment of a molten salt electrolysis tank concerning the present invention. It is sectional drawing cut | disconnected along the II line | wire of FIG.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited only to these Examples.

  The method for measuring the water content in the molten salt according to the present invention is such that the molten salt is dissolved in a dehydrated methanol solvent, a part thereof is sampled, and the Karl Fischer reagent (trade name “Hydranal Composite 5” manufactured by Sigma-Aldrich) is used. The titration was performed with

Example 1
Using the molten salt electrolytic purification apparatus shown in FIG. 1, an alloy containing metal indium was supplied to the anode chamber with the following apparatus configuration and molten salt composition, and the purified metal indium was electrolytically deposited in the cathode chamber. .

1. Apparatus configuration 1) Anode chamber Size: 280 mm long x 350 mm wide x 140 mm deep, 5 mm thick
Material: Stainless steel (SUS304)
Shape: Square tank (with anolyte extraction nozzle)
2) Inner cylinder Size: Length 250mm x width 250mm x height 250mm, thickness 3mm
Material: Quartz glass Shape: Square tank (Bottom: Opening, Lower side: 30 mm x 30 mm slits on each side, 2 locations,
Upper part: with 2 nozzles)
3) Cathode chamber Size: Length 30 mm × Width 200 mm × Depth 30 mm, Thickness 3 mm, 5 Material: Quartz glass Shape: Square tank 5 Molten salt bath Composition: Indium monochloride: Zinc chloride = 78:22 (mol%)
Indium chloride 80% by weight Water content 0.4wt%
Electrolysis temperature: 300 ° C
The composition of the metal indium-containing alloy (anolyte 9) supplied to the anode chamber 1 was metal indium 90.3 wt% and metal tin 9.7 wt%, and 80.1 kg was charged at the start of the electrolysis operation. 100 A is energized with a DC power generator 13 (Kikusui Electronics Co., Ltd., trade name “PAS10-105”), the anode current density is 16 A / dm ² , and the cathode current density is 33 A / dm ² continuously. Driving was carried out. The metal indium electrolytically deposited in the cathode chamber 8 averaged 10.2 kg per day and could be continuously recovered from the outlet 7. The anode chamber 1 was supplied with 10.2 kg of the alloy having the above composition per day. On the 14th day from the start of operation, since the tin content of the indium-containing alloy held in the anode chamber 1 has become slightly higher, 40.2 kg of the anolyte 9 is extracted from the extraction nozzle 4 while the electrolytic operation is continued. 40.2 kg of the alloy having the above composition was supplied in a molten state, and electrolysis was continued. At the time of this anolyte exchange, the molten salt 10 can be operated without coming into contact with the atmosphere, and no deterioration such as discoloration or solidification of the molten salt 10 was observed.

  The tin content in the metal indium electrodeposited on the cathode by the 14-day molten salt electrolytic purification was 580 wtppm, and the tin content in the anolyte extracted from the extraction nozzle 4 was 25.6 wt%. The water content in the molten salt was 0.3 wt%.

Comparative Example 1
A molten salt electrolytic cell described in Patent Document 1 was manufactured, and electrolytic refining of metal indium was performed at the same production rate as in Example 1. The apparatus configuration and molten salt bath composition were as follows.

1. Device configuration 1) Main body (cathode chamber)
Size: Inner diameter 400mmφ x Depth 300mm, Internal volume 37.7L, Thickness 5mm
Material: Stainless steel (SUS316)
Shape: Cylindrical, with catholyte extraction nozzle, top with lid with raw material supply nozzle.

2) Anode chamber Size: inner diameter 260 mmφ × depth 140 mm, internal volume 7.4 L, thickness 5 mm
Material: Alumina Shape: Cylindrical crucible 3) Insulation cover inside the body (upper part)
Size: Internal diameter 380mmφ x Depth 250mm, thickness 5mm
Material: Quartz glass Shape: Cylindrical Molten salt bath Composition: indium monochloride: zinc chloride = 78: 22 (mol%), water content 0.6 wt%
Electrolysis temperature: 300 ° C
First, 45.2 kg of the metal indium-containing alloy (metal indium 90.3 wt%, metal tin 9.7 wt%) used in Example 1 was placed in the anode chamber and placed in the center of the electrolytic cell. Subsequently, 40.3 kg of metal indium was charged between the insulating cover on the inside of the main body and the anode chamber, 32.9 kg of molten salt having the above composition was added, a current bar was set, and a DC power source generator 13 (manufactured by Kikusui Electronics Corporation) , 100A was energized under the trade name “PAS10-105”). The current density of the anode was 19 A / dm ² and the current density of the cathode was 18 A / dm ² , and continuous operation was performed. The metal indium electrolytically deposited in the cathode chamber averaged 10.2 kg per day and could be recovered continuously. In order to supply 10.2 kg of the alloy having the above composition to the anode chamber per day, the raw material supply nozzle installed on the lid on the upper part of the electrolytic cell was opened and poured in a molten state. Thus, although it was a short time, the water | moisture content in air | atmosphere mixed in the gaseous-phase part of an electrolytic cell. On the sixth day from the start of operation, since the tin content of the metal indium-containing alloy held in the anode chamber increased, the electrolysis operation was stopped, and the anode chamber (crucible) was taken out while the temperature was as high as 280 ° C. 34.8 kg of the anolyte was extracted, and instead 45.2 kg of the alloy having the above composition was charged in a molten state, returned to the center of the electrolytic cell, and electrolysis was resumed. At the time of this anolyte exchange, the molten salt was in contact with the atmosphere, so that the upper part of the molten salt was partially solidified, and deterioration of the molten salt was observed. This series of operations was continued for 14 days as in Example 1.

  The tin content in the metal indium electrodeposited on the cathode by this 14-day molten salt electrolytic refining averaged 1530 wtppm, and the tin content in the anolyte extracted from the anode chamber averaged 26.7 wt%. The content of tin in the metal indium electrolytically deposited was as high as about 3 times, and the quality was insufficient. Further, a pale yellow solid was floating on the upper layer of the molten salt after 14 days, and the deterioration was remarkable when the water content in the molten salt was 0.9 wt%.

Comparative Example 2
A molten salt electrolytic cell described in Patent Document 2 was manufactured and subjected to electrolytic purification. The apparatus configuration and molten salt bath composition were as follows.

1. Device configuration 1) Body Size: Inner diameter 300mmφ x Depth 300mm, thickness 5mm
Material: Stainless steel (SUS316)
Shape: Cylinder, with catholyte extraction nozzle 2) Cover inside the body Size: Inner diameter 280 mmφ x Depth 280 mm, Thickness 5 mm
Material: Quartz glass Shape: Cylinder 3) Anode chamber Size: Inner diameter 250 mmφ x Depth 180 mm, Internal volume 8.8 L, Thickness 10 mm
Material: Porous alumina Shape: Cylindrical crucible Molten salt bath Composition: Indium monochloride: Zinc chloride = 78:22 (mol%)
Electrolysis temperature: 300 ° C
50.9 kg of the metal indium-containing alloy (metal indium 90.3 wt%, metal tin 9.7 wt%) used in Example 1 was placed in the anode chamber and set in the main body of the electrolytic cell. Subsequently, 22.5 kg of metal indium was charged between the insulating cover inside the main body and the anode chamber, 16.6 kg of molten salt having the above composition was charged, and the temperature was 300 ° C. An energizing rod was set, and 100 A was energized with a DC power generator 13 (manufactured by Kikusui Electronics Co., Ltd., trade name “PAS10-105”). The operation was started with an anode current density of 20 A / dm ² and a cathode current density of 16 A / dm ² . Since the electrolytic cell voltage suddenly increased from about 8 hours after the start of operation, the electrolytic operation was stopped and the electrolytic cell was checked. As a result, the molten salt permeates the porous alumina side wall of the anode chamber, the amount of molten salt retained between the anode and the cathode is reduced, and a part of the bottom surface of the anode chamber is not in contact with the electrolyte. It became clear that the electrical resistance was increased.

Example 2
In the apparatus configuration shown in Example 1, an alloy containing metal tin (anolyte 9) was supplied to the anode chamber 1, and purified metal tin was electrolytically deposited in the cathode chamber 8. The composition of the molten salt 10 was a mixed molten salt of 76 wt% tin chloride and 24 wt% zinc chloride, and the electrolysis temperature was 350 ° C.

  The composition of the metal tin-containing alloy supplied to the anode chamber 1 was metal tin 95.3 wt% and metal lead 4.7 wt%, and 80.3 kg was charged at the start of the electrolysis operation. The DC power generator 13 (manufactured by Kikusui Electronics Co., Ltd., trade name “PAS10-105”) was energized with 100 A and continuously operated. Metal tin electrolytically deposited in the cathode chamber 8 averaged 5.3 kg per day and could be continuously recovered from the outlet 7. The anode chamber 1 was supplied with 5.3 kg of the alloy having the above composition per day. On the 14th day from the start of operation, since the lead content of the tin-containing alloy held in the anode chamber 1 increased, 41.2 kg of the anolyte 9 was extracted from the extraction nozzle 4 while the electrolysis operation was continued. 41.2 kg was supplied and electrolysis was continued.

  As a result of the 14-day molten salt electrorefining, the lead content in the metal tin electrodeposited on the cathode was 12 wtppm, and the lead content in the anolyte extracted from the extraction nozzle 4 was 8.7 wt%.

  An object of the present invention is to increase the purity of a useful low melting point metal, to suppress the deterioration of molten salt over a long period of time, and to easily supply and withdraw an alloy containing a low melting point metal. The present invention relates to a molten salt electrorefining apparatus and a method for purifying a low melting point metal that can suppress deterioration of the molten salt and increase the purity of a useful low melting point metal.

1: anode chamber 2: inner cylinder 3: inlet port 4: extraction nozzle 5: inert gas inlet port 6: exhaust gas outlet port 7: outlet port 8: cathode chamber 9: anolyte 10: molten salt 11: catholyte 12: Heater 13: DC power generator 14: Anode lead 15: Cathode lead

Claims (12)

A molten salt electrolytic cell for purifying a low melting point metal,
An anode chamber containing an alloy liquid containing the low-melting-point metal and having an opening into which an anode conductor can be inserted;
An inner cylinder for holding the molten salt layer of the low-melting-point metal halide on the contained liquid material, and allowing the liquid material to communicate in the anode chamber without causing the molten salt layer to flow outside;
It has an inlet and an outlet for the low-melting-point metal after purification, and is arranged so that the inlet is located in the molten salt layer. A cathode conductor can be inserted, and the inside is the low-melting-point metal. A molten salt electrolysis cell comprising a filled cathode chamber. The molten salt electrolyzer according to claim 1, wherein the inner cylinder is composed of one or more selected from glass, ceramics, and fluororesin. The molten salt electrolyzer according to claim 1 or 2, wherein the inner cylinder is provided with an inert gas inlet and an exhaust gas outlet. The molten salt electrolytic cell according to claim 1, wherein the cathode chamber is made of glass. The molten salt electrolyzer according to claim 1, wherein the cathode chamber has a plurality of the inlets. The molten salt electrolytic cell according to any one of claims 1 to 5, wherein the anode chamber is composed of one or more selected from stainless steel, iron, titanium, and graphite. The molten salt electrolyzer according to claim 1, wherein the anode chamber is made of stainless steel. The molten salt electrolyzer according to claim 1, wherein the anode chamber further has a lead-out port for leading out the refined alloy containing the low melting point metal. The molten salt electrolytic cell according to claim 8, wherein a nozzle is formed at the outlet in the anode chamber. In the molten salt electrolyzer according to any one of claims 1 to 9,
An alloy containing one or more metals selected from indium, tin and gallium is accommodated in the anode chamber, and a molten metal halide corresponding to the metal is held on the liquid material of the alloy in the inner cylinder. One or more metals selected from purified indium, tin, and gallium from the outlet of the cathode chamber by applying a voltage with the anode conductor and cathode conductor inserted, and performing molten salt electrolysis A method for purifying a low melting point metal, characterized in that The method for purifying a low-melting-point metal according to claim 10, wherein the operating temperature for molten salt electrolysis is 50 ° C. to 400 ° C. Method for purifying a low-melting metal according to claim 10 or 11 current density at the time of the molten salt electrolysis is characterized in that it is a 1~200A / dm ^2.

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