WO2009107339A1

WO2009107339A1 - Manufacturing method for a reducing metal and an electrolytic apparatus to be used in the same

Info

Publication number: WO2009107339A1
Application number: PCT/JP2009/000614
Authority: WO
Inventors: 山口雅憲; 小野有一; 山中理
Original assignee: 東邦チタニウム株式会社
Priority date: 2008-02-27
Filing date: 2009-02-17
Publication date: 2009-09-03
Also published as: JPWO2009107339A1

Abstract

Disclosed are a method to efficiently manufacture, through molten salt electrolysis, a reducing metal suitable for the reduction reaction of titanium tetrachloride or titanium, and a molten salt electrolytic apparatus to be used in the same. The disclosed method of manufacturing a reducing metal involves filling a molten salt electrolytic cell with an electrolytic bath comprising a chloride of a reducing metal, immersing the anode and the cathode, and performing molten salt electrolysis; wherein: the electrolytic cell is divided into an anode chamber and a cathode chamber using a partition, and an extraction pipe for the produced metal is immersed in the cathode chamber. The metal produced in the electrolytic bath within the cathode chamber rises and forms a layer of reducing metal, which is kept at a constant thickness, while the reducing metal within the reducing metal layer is continuously extracted through the extraction pipe. Also disclosed is a molten salt electrolytic apparatus to be used in the manufacturing method of this reducing metal.

Description

Method for producing reducing metal and molten salt electrolysis apparatus used therefor

The present invention relates to a method for producing a reducing metal from a metal chloride by molten salt electrolysis and an apparatus therefor.

Demand for titanium sponge is expected to increase in the future, supported by the recent strong demand. In addition, titanium users continue to receive cost reduction requests, and efforts to improve operations have been made. As a result, the cost of titanium sponge production in recent years has been reduced by Kaya compared to the conventional cost.

However, since commercial sponge titanium is manufactured based on a crawl method based on a batch process that repeats discontinuous processes, it is difficult to further reduce costs by increasing the efficiency of the process. .

Under such circumstances, the FFC method (for example, refer to Patent Document 1) in which titanium oxide is directly reduced as a raw material with metal calcium to directly produce titanium metal, or titanium tetrachloride as a raw material is used as a metal calcium. A JTS method in which metal titanium ingot is continuously produced by reducing the plasma to produce metal titanium ingot has been conceived and studied (for example, see Patent Document 2).

In the above-described novel method for producing titanium metal, metallic calcium is used as a reducing agent for obtaining titanium. Therefore, metallic titanium is generated along with the reduction reaction, and calcium chloride is also produced as a by-product. The calcium chloride can be regenerated into metallic calcium and chlorine gas by molten salt electrolysis.

In addition, although calcium metal produced by molten salt electrolysis has solubility in calcium chloride, even if calcium chloride is contained in metal calcium as a reducing agent in the above-described novel method for producing metal titanium, The reaction is not significantly inhibited by the calcium chloride, and it is considered that the operation is possible.

However, from the viewpoint of reduction reaction rate and handling, it is considered preferable that the concentration of metallic calcium produced by molten salt electrolysis of calcium chloride is as high as possible.

For such a viewpoint, in molten salt electrolysis of calcium chloride, a method of depositing and forming solid metallic calcium on the cathode surface immersed in an electrolytic cell (see, for example, Patent Document 3) or adjusting the electrolytic bath composition A method for efficiently recovering metallic calcium by reducing the solubility of metallic calcium in calcium chloride has also been studied (see, for example, Patent Document 4).

However, even with the above method, the metal calcium is partially dissipated in the electrolytic bath, and a certain amount of calcium chloride is mixed in the recovered metal calcium, so that it is recovered. There is still room for improvement in terms of recovery yield and purity of metallic calcium.

On the other hand, there is also known a technique capable of effectively suppressing dissolution of metallic calcium in the electrolytic bath by adding calcium carbide to the electrolytic bath (see, for example, Patent Document 5). However, it is considered unfavorable because the carbide is mixed in the calcium metal and finally moves to the metal titanium to reduce the purity of the metal titanium.

Thus, there is a demand for a technique for producing high-purity metallic calcium with a high yield by molten salt electrolysis of calcium chloride.

WO2003-048399 JP 2005-133195 A WO 2006-003864 WO2006-040978 JP-A-49-070808

The present invention relates to a preferred method for producing a reducing metal suitable for a reduction reaction of titanium tetrachloride and titanium oxide, and a molten salt electrolysis apparatus used therefor, and in particular, reduction of a molten state efficiently by molten salt electrolysis. An object of the present invention is to provide a method for producing a porous metal and a molten salt electrolysis apparatus for producing a metal using the same.

As a result of extensive studies in view of such circumstances, a method for producing a reducing metal using a molten salt electrolysis apparatus, which is formed by being floated after being produced in an electrolytic bath in a cathode chamber constituting the electrolysis apparatus. A high concentration of the reducing metal can be produced by continuously extracting the reducing metal from the system while keeping the thickness of the reduced metal layer constant. It has been found that by using a reducing metal, the reduction reaction of titanium tetrachloride or titanium oxide can be advanced efficiently, and the present invention has been completed.

That is, the present invention is a method for producing a reducing metal in which a molten salt electrolytic cell is filled with an electrolytic bath made of a reducing metal chloride, and an anode and a cathode are immersed and arranged to perform molten salt electrolysis. The partition wall is divided into an anode chamber and a cathode chamber by partition walls, and a formed metal extraction tube is immersed on the cathode chamber side, and after forming in an electrolytic bath in the cathode chamber, the thickness of the reducible metal layer formed by floating is set. It is characterized in that the reducing metal in the reducing metal layer is continuously extracted out of the system by a generated metal extraction pipe while being kept constant.

In the above, it is preferable that the anode chamber and the cathode chamber are an anode partition and a cathode partition surrounding the anode and the cathode.

The present invention has a preferred aspect of performing molten salt electrolysis while controlling the lower end surface of the reducing metal layer in a range deeper than the lower end surface of the generated metal extraction tube and shallower than the lower end surface of the cathode, Also, from the start of molten salt electrolysis until the thickness of the reducible metal layer in a steady state is reached, the reducible metal produced in the cathode chamber diffuses into the electrolytic bath outside the cathode chamber without extracting the reducible metal. It is a preferable aspect to perform molten salt electrolysis at a speed larger than the speed of the heat treatment.

In the present invention, the cathode chamber means an electrolytic bath existing inside a cathode partition including a cathode and an upper space thereof. Similarly, the anode chamber means an electrolytic bath existing inside an anode partition including an anode and a space above the electrolytic bath.

The thickness of the reducing metal layer in the electrolytic bath can be detected by measuring the electrical resistance in the electrolytic bath held in the cathode chamber.

Furthermore, it is a preferable aspect that the electrolytic bath of the raw material is uniformly supplied from above with respect to the electrolytic bath surface held in the anode chamber.

In the present invention, metallic calcium containing the electrolytic bath produced by the above method can be used as a reducing agent for titanium tetrachloride.

A molten salt electrolyzer for producing a reducing metal according to the present invention includes an electrolytic cell, an electrolytic bath that fills the electrolytic cell, an anode and a cathode that are immersed in the electrolytic bath, and surrounds the anode and defines an anode chamber. An anode partition and a cathode partition surrounding the cathode and partitioning the cathode chamber are provided.

In the cathode chamber, it is preferable that a sensor for measuring electrical conductivity is immersed in an electrolytic bath.

The preferred embodiment is that the cathode is inserted and arranged in the electrolytic bath from the bottom of the cathode chamber.

In a preferred embodiment, a raw material electrolytic bath supply nozzle is disposed in the space above the bath surface of the anode chamber.

Furthermore, it is preferable that the anode partition is made of porous alumina and the cathode partition is made of dense silicon nitride.

By using the reducing metal production method and the molten salt electrolysis apparatus according to the present invention, the reducing metal can be produced with high yield. As a result, when the reducing metal is used as a reducing agent for titanium tetrachloride or titanium oxide, the reduction reaction can be carried out stably.

It is a schematic diagram which shows one Embodiment of the molten salt electrolysis apparatus of this invention. It is a schematic diagram which shows other embodiment of the molten salt electrolysis apparatus of this invention. It is a schematic diagram which shows the conventional molten salt electrolysis apparatus in the comparative example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electrolytic cell, 11 ... Electrolytic bath, 12 ... Anode chamber, 13 ... Cathode chamber, 2 ... Anode, 21 ... Anode, 3 ... Cathode, 31 ... Cathode, 32 ... Cathode insulator, 33 ... Cathode, 4 ... Partition DESCRIPTION OF SYMBOLS 41 ... Anode partition, 42 ... Cathode partition, 5 ... Electrolytic bath supply pipe, 6 ... Reducing metal discharge pipe, 7 ... Reducing metal layer, 71 ... Chlorine gas, 8 ... Electric resistance measuring sensor, 9 ... Fan.

The best embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 shows an apparatus configuration example according to a preferred molten salt electrolysis apparatus for carrying out the production of the reducing metal of the present invention. In the molten salt electrolysis apparatus according to the present invention, an electrolytic bath 1 is filled with a molten electrolytic bath 11, an anode 2 and a cathode 3 are immersed, and an anode partition wall 41 so as to surround the anode 2 and the cathode 3. And a cathode barrier 42 is provided. The electrolytic bath 11 and its upper space surrounded by the anode partition 41 and the cathode partition 42 are defined as an anode chamber 12 and a cathode chamber 13, respectively.

In this molten salt electrolysis apparatus, when a voltage is applied between the anode 2 and the cathode 3 to start electrolysis, a reducing metal is generated in the cathode chamber 13 and chlorine gas 71 is generated in the anode chamber 12. In the present invention, by arranging the anode partition 41 and the cathode partition 42 as described above, the contact between the molten reducing metal generated on the surface of the cathode 3 and the chlorine gas 71 generated on the anode 2 can be effectively performed. Can be suppressed. When the generated reducible metal is concentrated to form the reducible metal layer 7, it is extracted by the generated metal extraction pipe 6 and used in the next step. The electrolytic bath 11 consumed by the molten salt electrolysis is replenished to the anode chamber 12 from the electrolytic bath supply pipe 5.

The present invention is a method for producing a reducing metal by using a molten salt electrolysis apparatus as described above and subjecting the electrolytic bath 11 held in the electrolytic cell 1 to molten salt electrolysis, and is configured in the electrolytic cell 1. By adjusting the generation amount and extraction amount of the reducing metal generated in the cathode chamber 13, the layer thickness of the reducing metal layer 7 on the surface of the electrolytic bath suspended in the cathode chamber 13 is kept constant, The metal is continuously extracted from the system.

As described above, by performing the operation while keeping the thickness of the reducing metal layer 7 constant, the lower end surface of the generated metal extraction pipe 6 immersed and held in the reducing metal layer 7 is reduced to the reducing metal layer 7. It can always be held in the reducing metal layer 7 so as not to protrude from the inside, and as a result, it is possible to effectively suppress the entrainment of the electrolytic bath 11 in contact with the lower end surface of the reducing metal layer 7. It plays. As a result, there is an effect that the concentration of the reducing metal extracted from the generated metal extraction pipe 6 to the outside of the system can be maintained almost constant.

This has the effect that when the reducing metal is metallic calcium, the reduction reaction in the case of producing titanium titanium by reducing titanium tetrachloride with the metallic calcium can be stably advanced.

In the present invention, the thickness of the reducing metal layer 7 is preferably maintained at 5% or more with respect to the entire depth of the electrolytic bath held in the cathode partition wall 42. By maintaining in such a range, the concentration of metal calcium in the electrolytic bath held in the cathode partition wall 42 can be maintained in a saturated state, and as a result, the metal calcium generated in the cathode 3 can be kept in the reducing metal layer 7. The effect is that it can be efficiently combined.

If the thickness of the reducible metal layer 7 is less than 5%, the inside of the cathode chamber 13 does not reach the metal calcium saturation concentration, and the generated metal calcium diffuses. Moreover, there exists a possibility that the production | generation metal extraction pipe | tube 6 may involve an electrolytic bath.

On the other hand, the upper limit of the thickness of the reducing metal layer 7 is preferably controlled so that the bottom surface of the reducing metal layer 7 does not exceed the lower end of the cathode 3. When the bottom surface of the reducing metal layer 7 grows below the lower end surface of the cathode 3, the bottom surface of the reducing metal layer 7 itself forms a cathode, and metallic calcium is generated on the surface. As a result, the metallic calcium tends to flow out of the bath from the bottom of the cathode partition wall 42, which is not preferable.

In the present invention, the reducing metal produced in the cathode chamber 13 diffuses into the electrolytic bath outside the cathode chamber until the layer thickness of the reducing metal layer 7 maintained in a steady state is reached after the start of molten salt electrolysis. It is preferable that the molten salt electrolysis is performed at a speed higher than the speed of the heating.

When the reducing metal according to the present invention is metallic calcium, it has a certain solubility in the electrolytic bath, and as a result, part of the metallic calcium produced at the cathode may flow out of the cathode chamber. is there. For this reason, molten salt electrolysis is started while maintaining the generation rate of the reducing metal at the cathode to be higher than the flow rate of the reducing metal from the cathode chamber to the outside. Until the calcium concentration falls within the above-described range, it is preferable to operate so as not to extract the reducing metal bath and to supply the raw electrolytic bath.

As a result, the thickness of the reducing metal layer 7 in the electrolytic bath held in the cathode chamber can be stably maintained at a predetermined thickness, and as a result, the dissolution loss of metallic calcium generated in the cathode is effectively reduced. There is an effect that it can be suppressed.

In the present invention, it is preferable to immerse the electric resistance measurement sensor 8 in the reducing metal layer 7 surrounded by the cathode partition wall 42 and the electrolytic bath below the reducing metal layer 7. When the reducing metal is metallic calcium and the electrolytic bath is calcium chloride, the metallic calcium has solubility with respect to calcium chloride, so that the calcium chloride in which metallic calcium is dissolved flows out from the cathode chamber 13 to the outside. As a result, the case where the metal calcium concentration which exists in the electrolytic bath in the cathode chamber 13 falls is assumed. The sensor 8 described above has an effect that such a state can be accurately detected from the outside.

The sensor 8 can be composed of, for example, two conductive wires in which only the tip of the insulator is opened. By applying a constant voltage between the tips of the wires, it is possible to detect the change in the electrical resistance of the electrolytic bath in contact with the tips from the outside.

The electrolytic bath supply pipe 5 disposed in the present invention is preferably disposed in the upper space in the anode chamber 12, and a plurality of electrolytic baths are uniformly supplied to the entire surface of the electrolytic bath 11. More preferably, it is configured as a pipe.

As described above, the raw material electrolytic bath is uniformly supplied from the upper space of the electrolytic bath 11 existing in the anode chamber 12 toward the electrolytic bath surface, thereby generating bubbles of chlorine gas generated on the surface of the anode 2. The accompanying upward flow of the electrolytic bath 11 can be effectively suppressed. As a result, it is possible to effectively avoid the invasion of metallic calcium flowing out from the cathode chamber 13 to the outside.

In the present invention, the anode 2 is preferably composed of graphite. By configuring the anode 2 with graphite, corrosion from chlorine gas generated at the anode 2 can be effectively suppressed.

The material of the anode partition wall 41 is preferably a material that can withstand chlorine gas, and specifically, it is preferably composed of ceramics such as alumina or magnesia. Further, the anode partition wall 41 preferably has pores such that the electrolytic bath 11 can flow and chlorine gas cannot pass through, and specifically has a porosity of about 10 to 30%. Preferably it is.

On the other hand, the cathode 3 is preferably composed of a metal that is not easily corroded by the metal in order to generate the reducing metal layer 7 in a molten state. In this invention, it is preferable to comprise with carbon steel or stainless steel. Furthermore, other high melting point metals such as titanium, tantalum or tungsten can be used.

The cathode partition 42 provided around the cathode 3 is preferably made of a material that can withstand the reducing metal produced by the cathode 3, and is preferably made of a dense material that does not penetrate the reducing metal. Silicon nitride is preferred as such a material. This is because the silicon nitride has a low reactivity with the reducing metal produced at the cathode 3 and is suitable as a constituent material of the cathode partition wall 42, and a dense grade of silicon nitride can be obtained relatively easily.

The method for producing a reducible metal using the molten salt electrolysis apparatus according to the present invention maintains a constant thickness of the reducible metal layer 7 suspended on the electrolytic bath surface in the cathode chamber constituting the molten salt electrolyzer. However, the reducing metal is continuously extracted from the system.

The above-described characteristics are that both the electrolytic bath 11 is continuously supplied into the anode chamber 12 and the reducing metal layer 7 retained and held in the cathode chamber 13 is extracted from the system by the generated metal extraction pipe 6. This can be achieved by adjusting the amount balance.

Further, at this time, it is preferable that the electrical resistance in the electrolytic bath 11 held in the cathode chamber 13 is withdrawn while being appropriately monitored by the sensor 8 immersed in the electrolytic bath. As a result, when a tendency that the concentration of metallic calcium in the electrolytic bath existing in the cathode chamber 13 is lowered is detected, the generated metal extraction tube immersed in the reducing metal layer 7 in the cathode chamber 13 is detected. By suppressing the extraction amount from 6, the effect that the layer thickness of the reducing metal layer 7 can be controlled within a certain range is achieved.

Further, it is preferable that the sensor 8 is separately provided in the vicinity of the lower end surface of the cathode 3. The sensor 8 detects the vertical position of the lower end surface of the reducible metal layer 7 at an early stage, and effectively avoids the state in which the reducible metal layer 7 is generated below the lower end of the cathode 3. It has the effect of being able to. As described above, when the reducing metal layer 7 grows downward beyond the lower end surface of the cathode 3, it is not preferable because it is electrically integrated with the cathode 3 to form a so-called molten cathode. Therefore, as described above, a sensor 8 is separately provided in the vicinity of the lower end surface of the cathode 3 to control the position of the lower end surface of the reducing metal layer 7 so as not to extend below the lower end surface of the cathode 3. Thus, there is an effect that the formation of the above-described molten cathode can be effectively suppressed.

In the present invention, the sensor 8 is preferably immersed not only in the electrolytic bath in the cathode chamber 13 but also outside the cathode chamber 13. If the molten salt electrolysis reaction is continued for a long time, the reducing metal concentration in the electrolytic bath 11 gradually increases, and as a result, the electrical resistance of the electrolytic bath 11 may decrease, and it may be difficult to continue the molten salt electrolysis. It is. By separately disposing the sensor 8 in the electrolytic bath 11, the above-described state can be detected from the outside at an early stage.

FIG. 2 shows another preferred embodiment according to the present invention. In this embodiment, the cathode 31 is disposed through the electrolytic bath 11 from the bottom surface of the cathode chamber through the insulator 32.

As a result, the reducing metal generated at the cathode 31 is separated from the cathode 31 and floats and accumulates on the bath surface, so that the above-described reducing metal layer 7 and the cathode 31 are integrated as a molten cathode. Can be effectively suppressed. By appropriately selecting the relationship between the height of the cathode 3 and the lower end position of the partition wall 4, the phenomenon that the reducing metal layer 7 flows out to the anode side via the lower end portion of the partition wall 4 is suppressed. The reducible metal layer 7 can be retained to the maximum extent in the cathode-side electrolytic bath partitioned by (1). By ensuring a sufficient amount of retention of the reducing metal layer 7, it is possible to stabilize the supply amount of metallic calcium supplied to the reduction process.

Further, by ensuring a sufficient separation distance between the calcium metal generated at the cathode 31 and the electrolytic bath 11, it is possible to generate the reducing metal layer 7 having a high metal calcium concentration.

Furthermore, by arranging the cathode 31 at the bottom of the electrolytic cell 1 as shown in FIG. 2, there is a space in the upper space of the electrolytic bath 11 compared to FIG. 1, for example, a sensor for measuring electrical resistance. As a result, the necessary number of 8 can be efficiently arranged.

In the present invention, the lower end surface of the reducible metal layer 7 is located deeper than the generated metal extraction pipe 6 immersed in the reducible metal layer 7 and is immersed in the electrolytic bath 11. It is preferable to arrange at a position shallower than the upper end of the cathode 31.

By disposing the reducing metal layer 7 in such a range, not only can the reducing metal layer 7 be extracted from the system more efficiently than the generated metal extraction tube 8, but also the contact with the cathode 31 is effective. As a result, it is possible to proceed with efficient electrolysis.

In the present invention, the temperature of the electrolytic bath 11 is preferably kept at a temperature higher than the melting point (845 ° C.) of metallic calcium. However, heating the temperature of the electrolytic bath too much is not preferable because it causes evaporation loss of the reductive metal produced electrolytically. Therefore, it is preferable to heat and hold the electrolytic bath up to 900 ° C.

The electrolytic bath used in the present invention is preferably constituted by adding calcium chloride alone or a second component such as potassium chloride or calcium fluoride. In the present invention, it is particularly preferable to add potassium chloride to calcium chloride. The addition amount is preferably in the range of 5 to 25 mol% with respect to the whole. As a result, there is an effect that the solubility of metallic calcium produced at the cathode can also be effectively suppressed.
Furthermore, although the melting point of calcium chloride alone is 780 ° C., the melting point of the electrolytic bath can be lowered to 756 ° C. to 640 ° C. by adding 5 to 25 mol% of potassium chloride as the second component. This has the effect that it can be easily extracted.

Further, in FIG. 1 of the present invention, an anode partition and a cathode partition are provided, and in FIG. 2, only one partition is provided. However, the present invention is not limited to these embodiments. In FIG. 2, an anode barrier and a cathode barrier can also be provided.

As described above, there is an effect that a reducing metal such as metallic calcium can be efficiently produced by the molten salt electrolysis apparatus according to the present invention and the method using the same.

[Example 1]
1) Device configuration Electrolytic cell 1: Titanium Anode 2: Graphite Cathode 3: Carbon steel Anode-side partition wall 41: Alumina tube (porosity; 20%)
Cathode side partition 42: Silicon nitride tube Sensor 10: Electrode material: Stainless steel 2) Electrolytic bath Bath composition: Calcium chloride (85 mol%) + Potassium chloride (15 mol%)
Bath temperature: 880 ° C
3) Results Under the above conditions, the sensor 8 detects the electrical conductivity in the reducing metal layer 7 shown in FIG. 1 while the lower end surface of the reducing metal layer 7 is moved from the lower end surface of the generated metal extraction pipe 6. The molten salt was electrolyzed with calcium chloride so as to have a constant layer thickness while maintaining the depth deeper and shallower than the lower end surface of the cathode 3. As a result, it was possible to stably extract a reducing metal containing metallic calcium having a concentration of 90 to 95 wt%. The current efficiency at this time was 85%.

[Example 2]
In Example 1, molten metal electrolysis of calcium chloride was performed under the same conditions except that FIG. 2 was used, and the reducing metal produced at the cathode 31 was detected while the electrical conductivity in the reducing metal layer 7 was detected by the sensor 8. The metal calcium which comprises the layer 7 was extracted out of the system. The metal calcium concentration in the extracted reducing metal layer 7 was in the range of 90 to 95 wt%. The current efficiency at this time was 85%.

[Comparative Example 1]
Molten salt electrolysis of calcium chloride under the same conditions except that the lower end surface of the reducing metal layer 7 was lower than the lower end surface of the cathode 3 and higher than the lower end surface of the cathode partition wall 42 in Example 1. As a result, during the electrolysis, the voltage between the electrodes decreased and the electrolysis reaction was interrupted. After the electrolytic cell 1 was cooled to room temperature, the electrolytic bath 11 was taken out, and small lumps of metallic calcium were found.

[Comparative Example 2]
Molten salt electrolysis was performed using a calcium chloride molten salt electrolysis apparatus as shown in the schematic cross-sectional view of FIG. Reference numeral 33 denotes a cylindrical cathode, which is provided with a flow hole for an electrolytic bath communicating with the outside and the inside. The electrolytic bath is supplied from the outside of the electrode by the supply of the electrolytic bath by the electrolytic bath supply pipe 5 and the rotation of the fan 9. It flows toward the inside. In Comparative Example 2, the metallic calcium produced in the cylindrical cathode 33 is retained inside the cylindrical cathode by the flow of the electrolytic bath from the outside to the inside of the electrode, and the retained molten metallic calcium is continuously formed. I pulled it out. The current efficiency achieved when the test was conducted remained at about 70-80%.

From the above examples and comparative examples, it was confirmed that by using the method and apparatus disclosed in the present invention, high purity metal calcium can be produced and recovered in a molten state while maintaining high current efficiency. It was.

Contributes to the cost reduction of titanium metal by making the production of reducing metals more efficient.

Claims

A method for producing a reducing metal in which a molten salt electrolyzer is filled with an electrolytic bath made of a chloride of a reducing metal, and an anode and a cathode are immersed and arranged to perform molten salt electrolysis,
The electrolytic cell is partitioned into an anode chamber and a cathode chamber by partition walls,
The generated metal extraction tube is immersed in the cathode chamber side,
After generating in the electrolytic bath in the cathode chamber, the reducing metal in the reducing metal layer is held by the generated metal extraction pipe while maintaining a constant thickness of the reducing metal layer formed by floating. A method for producing a reducing metal, which is continuously extracted out of the system.
The method for producing a reducing metal according to claim 1, wherein the anode chamber and the cathode chamber are an anode partition and a cathode partition surrounding the anode and the cathode.
The molten salt electrolysis is performed while controlling a lower end surface of the reducing metal layer in a range deeper than a lower end surface of the generated metal extraction pipe and shallower than a lower end surface of the cathode. The manufacturing method of the reducible metal as described in any one of.
From the start of the molten salt electrolysis until the thickness of the reducing metal maintained in a steady state is reached, the reducing metal is not extracted out of the system, and the reducing metal generated in the cathode chamber is The method for producing a reducible metal according to claim 1, wherein the molten salt electrolysis is performed at a generation rate larger than the diffusion rate into the electrolytic bath outside the cathode chamber.
2. The production of the reducing metal according to claim 1, wherein the thickness of the reducing metal layer in the electrolytic bath suspended in the cathode chamber is detected by measuring an electric resistance in the electrolytic bath. Method.
2. The method for producing a reducing metal according to claim 1, wherein the raw electrolytic bath is uniformly supplied from above to the electrolytic bath surface held in the anode chamber.
The method for producing a reducing metal according to claim 1, wherein the reducing metal is metallic calcium, metallic sodium, or metallic magnesium.
The electrolytic bath is composed of calcium chloride, sodium chloride, magnesium chloride alone, a mixed salt of calcium chloride and potassium chloride, or a mixed salt of calcium chloride and calcium fluoride. 2. A method for producing a reducing metal according to 1.
9. The method for producing a reducing metal according to claim 1, wherein metallic calcium containing an electrolytic bath produced by molten salt electrolysis is used as a reducing agent for titanium tetrachloride.
A molten salt electrolysis apparatus for producing a reducible metal, comprising an electrolytic cell, an electrolytic bath filling the electrolytic cell, an anode and a cathode immersed in the electrolytic bath, an anode surrounding the anode and defining an anode chamber A molten salt electrolysis apparatus comprising: a partition wall; and a cathode partition wall surrounding the cathode and defining a cathode chamber.
The molten salt electrolysis apparatus according to claim 10, wherein the cathode is inserted into the electrolytic bath from the bottom of the cathode chamber.
11. The molten salt electrolysis apparatus according to claim 10, wherein a reducing metal to be generated and a sensor for measuring electric resistance of the electrolytic bath are immersed in the cathode bath in the electrolytic bath.
The molten salt electrolysis apparatus according to claim 10, wherein a plurality of electrolytic bath supply pipes are disposed in a space above the bath surface of the anode chamber.
The molten salt electrolysis apparatus according to claim 10, wherein the plurality of electrolytic bath supply pipes are arranged uniformly over the entire area of the electrolytic bath surface of the anode chamber.
The molten salt electrolysis apparatus according to claim 10, wherein the anode partition is made of alumina.
The molten salt electrolysis apparatus according to claim 10, wherein the cathode partition is made of silicon nitride.