JP2009041089A - Electrolytic cell and production method of metal using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrolytic cell capable of suppressing back reaction by preventing a metal (e.g. Ca) produced on a cathode side from invading into an anode side and maintaining a high current efficiency, and a production method of an alkali metal, an alkaline earth metal or a rare earth metal using the electrolytic cell. <P>SOLUTION: The electrolytic cell is a flow-through electrolytic cell, in which the anode 1 chamber side is kept at a pressurized state relative to the cathode 2 chamber side during electrolysis. A pressurized state is such a state that a head difference exists between the anode chamber side and the cathode chamber side and can be achieved by the methods of bringing the liquid level of an electrolytic bath at the anode side higher than that at the cathode side, setting a higher pressure in a gaseous phase in the anode chamber relative to that in the cathode chamber (see figure (b)), applying a pumping pressure to the electrolytic bath at the anode side (see figure (a)), etc. The electrolytic cell can be used to continuously produce metals such as Na, Ca, Mg and La which are produced by the electrolysis method. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electrolytic cell capable of forming a one-way bath flow from an anode chamber to a cathode chamber and preventing an electrolytic product from entering the anode chamber at the cathode, and a metal manufacturing method using the electrolytic cell.

As an industrial method for producing metal Ti, a crawl method in which TiCl ₄ is reduced with Mg is generally used. However, since this method is a batch type, there is a problem that the product price becomes very high. On the other hand, a technique for producing Ti by reducing TiCl ₄ with Ca has been proposed.

This method, for example, as described in Patent Document 1, a step of separating the Ti particles Ca is reacted with TiCl ₄ to Ca in the molten CaCl ₂ was dissolved to produce a Ti grains reduction step and generates includes electrolytic process to increase the Ca concentration in the molten CaCl ₂ by the Ca concentration electrolytic molten CaCl ₂ was decreased with the generation of the Ti particles, reduction of TiCl ₄ with Ca generated by the electrolysis step in the reduction step This is a Ti production method used in the above, and has an advantage that the operation can be continuously performed by reusing Ca as a reducing agent.

Furthermore, the present inventors have studied the electrolytic process of molten CaCl ₂ , and as described in Patent Document 2, the electrolytic cell container that is long in one direction holding the molten salt, and the longitudinal direction of the electrolytic cell container The molten salt supply port is provided at one end in the longitudinal direction of the electrolytic cell container, and the Ca concentration generated by electrolysis of the molten salt is at the other end. An electrolytic cell provided with a molten salt outlet for extracting the molten salt out of the electrolytic cell was proposed.

Using this electrolytic cell, for example, Ca generated on the cathode side reacts with chlorine (Cl ₂₎ to produce the anode side to suppress the back reaction back to CaCl ₂ and while maintaining high current efficiency, Ca, etc. Effective metal fog forming metal (for example, a metal that is dissolved in a metal chloride like a mist like metal such as Ca, Li, Na, Al, etc.) In addition, a large amount of molten CaCl ₂ can be continuously electrolyzed.

  However, even with this electrolytic cell, the back reaction cannot be completely suppressed, and the current efficiency is reduced accordingly. This improvement in current efficiency is also an important issue in increasing the efficiency of the entire electrolysis process in the production of metallic Ti by Ca reduction.

In addition, the main purpose of this electrolytic cell is to continuously and stably obtain a Ca-concentrated molten salt that can be used in the method of producing Ti by reducing TiCl ₄ with Ca. If the metal Ca can be continuously produced by the electrolytic method, it will lead to further improvement of the method of supplying Ca to the reduction step in the production of metal Ti by Ca reduction. Furthermore, there is a possibility that the use for production of alkali metals and alkaline earth metals such as Na, Li, Be, and Mg currently produced by an electrolytic method may be opened.

JP 2005-133195 A JP 2007-63585 A

  The present invention was made in view of such a situation, an electrolytic cell capable of preventing Ca generated on the cathode side from entering the anode side, suppressing back reaction, and preventing a decrease in current efficiency, Another object of the present invention is to provide a method for producing a metal by an electrolysis method using alkali metal, alkaline earth metal or rare earth metal (particularly, metal Ca) currently produced by an electrolysis method using this electrolytic cell.

In order to achieve the above-mentioned object, the present inventors have repeatedly studied the generation of Ca by electrolysis of molten CaCl ₂ . As a result, in a fluidized electrolytic cell in which an electrolytic bath is supplied from one end of the electrolytic cell and electrolyzed while flowing in one direction near the cathode surface, the bath surface level of the cathode side electrolytic bath is higher than the bath surface level on the anode side. Or when the pressure in the portion above the bath surface of the electrolytic bath in the cathode chamber (hereinafter referred to as “gas phase portion”) is kept lower than the pressure in the gas phase portion of the anode chamber. In addition, it was confirmed that when the anode chamber side was pressurized with respect to the cathode chamber side, it was possible to effectively prevent Ca generated on the cathode side from entering the anode side.

  This invention was made | formed based on such knowledge, and the summary exists in the electrolytic cell of the following (1), and the manufacturing method of a metal (2) using this electrolytic cell.

  (1) An electrolytic bath having an anode and a cathode arranged in the vertical direction inside the electrolytic cell, an electrolytic bath supply port for supplying an electrolytic bath between the anode and the cathode, and a metal concentration generated by electrolysis of the electrolytic bath is A fluidized electrolytic cell provided with an electrolytic bath extraction port for extracting the enhanced electrolytic bath out of the electrolytic cell, and the cathode is disposed on the anode chamber side where the anode is disposed during electrolysis. An electrolytic cell comprising means capable of maintaining a pressurized state with respect to a cathode chamber side (hereinafter, simply referred to as “anode chamber side” and “cathode chamber side”).

  In this electrolytic cell, generally, an embodiment in which the cathode-side electrolytic bath and the anode-side electrolytic bath are separated by a partition wall, a diaphragm, a net, or the like is employed.

  The above-mentioned “the anode chamber side is pressurized with respect to the cathode chamber side” means that the liquid level of the electrolytic bath is higher on the anode side, or the pressure in the gas phase in the anode chamber is higher than the cathode chamber. A state where the pressure is relatively high with respect to the pressure in the gas phase portion, a state where pump pressure is applied to the anode-side electrolytic bath, and the like. In other words, using the concept of “head” used in the case of pump operation, it means that all the heads on the anode chamber side are larger than all the heads on the cathode chamber side. That is, there is a head difference between the anode chamber side and the cathode chamber side. Here, the head difference is a height (head) difference due to a difference in liquid level, a pressure head difference (a pressure difference between gas phase portions of the anode chamber and the cathode chamber, a pressure difference depending on the presence or absence of a pump pressure). .

In the electrolytic cell of the present invention, the following embodiments (1a) to (1c) can be adopted as the pressurized state. These embodiments may be implemented by combining two or more of them. For example, a mode may be adopted in which the electrolytic bath is further pumped into the anode-side electrolytic bath and the pump pressure is applied while the bath-surface level of the cathode-side electrolytic bath is maintained lower than the bath-surface level of the anode-side electrolytic bath.
(1a) The state in which the bath surface level of the cathode side electrolysis bath is maintained lower than the bath surface level of the anode side electrolysis bath. This state can be maintained by providing a weir in the cathode chamber or adjusting the amount of electrolytic bath supplied to the anode chamber.
(1b) A state in which the pressure in the gas phase portion in the anode chamber is maintained relatively higher than the pressure in the gas phase portion in the cathode chamber.
(1c) A state in which pump pressure is applied to the anode-side electrolytic bath.

  Further, in the electrolytic cell of the present invention, if a porous ceramic body is used as the diaphragm or partition wall of the electrolytic cell, the effect of preventing Ca generated on the cathode side from entering the anode side is further improved.

  (2) Using the electrolytic cell described in (1) above, using an alkali metal, alkaline earth metal or rare earth metal halide produced by an electrolysis method as an electrolytic bath, with the anode chamber side facing the cathode chamber side A method for producing a metal, characterized in that electrolysis is performed while maintaining a pressurized state.

  The term “alkali metal, alkaline earth metal, or rare earth metal” as used herein specifically refers to a metal that can be collected and produced by electrolyzing a molten salt containing a chloride or fluoride of each metal. And Na, Li, Be, Ca, Mg, La, Ce and the like.

  In this metal production method, an embodiment in which metallic calcium is obtained by using a calcium salt or a molten salt containing a calcium salt as an electrolytic bath can be employed.

  The electrolytic cell of the present invention is a fluidized electrolytic cell, and can maintain the anode chamber side in a pressurized state with respect to the cathode chamber side during electrolysis. Accordingly, it is possible to extremely effectively prevent Ca generated on the cathode side from entering the anode side, suppress back reaction, and maintain high current efficiency.

  Further, if this electrolytic cell is used, it is possible to continuously produce an alkali metal, alkaline earth metal or rare earth metal produced by an electrolysis method while maintaining high current efficiency.

  The electrolytic cell of the present invention is a fluidized electrolytic cell, and is provided with means capable of maintaining the anode chamber side in a pressurized state with respect to the cathode chamber side during electrolysis. It is a tank.

  FIG. 1 is a longitudinal sectional view schematically showing an example of the configuration of the main part of the electrolytic cell of the present invention. Both (a) and (b) are cylindrical electrolytic cells (representing a surface including the central axis). .

  This electrolytic cell has an anode 1 and a cathode 2 arranged in the vertical direction inside the electrolytic cell, and an electrolytic bath supply port for supplying an electrolytic bath between the anode 1 and the cathode 2 (in FIG. "Bath" or "denoted by a symbol representing the pump 5" and an electrolytic bath outlet (see Fig. 1) for extracting the electrolytic bath having an increased metal concentration generated by electrolysis of the electrolytic bath out of the electrolytic cell. A fluidized electrolytic cell in which the extraction direction is indicated by a white arrow), and the anode chamber side can be maintained in a pressurized state with respect to the cathode chamber side during electrolysis. An electrolytic cell comprising means capable of being used (for example, the pump 5 in FIG. 1A).

  The “electrolytic bath with an increased metal concentration” extracted from the electrolytic bath outlet includes, for example, an electrolyte bath in which a metal having a saturated concentration or a predetermined concentration is dissolved, and a molten or precipitated metal. Including an electrolytic bath.

  In this electrolytic cell, generally, an embodiment in which the cathode-side electrolytic bath and the anode-side electrolytic bath are separated by a partition wall, a diaphragm, a net, or the like is employed. Depending on the shape of the electrolytic cell and the like, a partition wall or the like may not be necessary, but it is desirable to provide a partition wall or the like to suppress the migration of Ca generated by electrolysis to the anode side.

  Separation of the cathode side electrolytic bath and the anode side electrolytic bath includes, in addition to the partition wall, the diaphragm, and the net, for example, a partition in which wires are stretched vertically at a narrow interval (that is, in the same direction as the flow of the electrolytic bath). Similarly to the diaphragm and the diaphragm, it is possible to use a material that has the effect of suppressing the migration of the electrolytically generated Ca to the anode side while keeping the conductivity between the cathode side electrolytic bath and the anode side electrolytic bath while separating both electrolytic baths. Good.

The reason why the electrolytic cell of the present invention uses such a fluid electrolytic cell is that, for example, only an electrolytic bath with an increased Ca concentration can be effectively extracted from the electrolytic cell by electrolysis. It is. That is, since the electrolytic bath (for example, molten CaCl ₂ ) supplied between the anode and the cathode in the electrolytic cell is given a unidirectional flow velocity in the vicinity of the cathode surface, the concentration of Ca generated at the cathode by electrolysis is reduced. The increased molten CaCl ₂ flows toward the outlet of the electrolytic cell, and mixing with molten CaCl ₂ having a low Ca concentration near the inlet is avoided.

  The characteristics of the electrolytic cell of the present invention are that such a fluidized electrolytic cell is used and that the anode chamber side can be maintained in a pressurized state with respect to the cathode chamber side during electrolysis, that is, the anode chamber side Is larger than all the heads on the cathode chamber side, and a head difference can be given to the anode chamber side and the cathode chamber side.

The reason why the anode chamber side can be maintained in a pressurized state with respect to the cathode chamber side is to form a one-way bath flow from the anode chamber to the cathode chamber, and the Ca generated by electrolysis to the anode chamber side. This is to prevent back reaction that migrates and reacts with Cl ₂ produced at the anode to return to CaCl ₂ . The specific aspect of this pressurization state is the state (1a), (1b) or (1c). Hereinafter, description will be given with reference to the drawings.

  The electrolytic cell shown in FIG. 1A employs a configuration in which a cylindrical anode 1 is disposed at the center and the entire inner surface of the outer peripheral portion functions as the cathode 2. Between the anode 1 and the cathode 2, a partition wall 3 provided with a large number of small holes (not shown) through which the electrolytic bath can pass is disposed.

In this FIG. 1 (a), for example, the molten CaCl ₂ was supplied from below the cathode compartment between the cathode 2 and the partition wall 3, electrolysis also similarly supplied from below to the anode chamber between the anode 1 and the partition wall 3 As a result, chlorine 4 is generated on the anode 1 side of the electrolytic cell, and Ca is generated on the cathode 2 side. Since the molten CaCl ₂ is given a flow rate in one direction, the Ca generated by the electrolysis is concentrated toward the upper side of the cathode chamber, and is indicated by a white arrow as molten CaCl ₂ containing Ca at a high concentration. Extracted in the direction. By adjusting the supply rate of molten CaCl ₂ to the cathode chamber, electrolysis conditions, bath temperature, etc., Ca can be generated to a state exceeding the saturation concentration, and Ca can be obtained as a melt or solid.

In the example shown in FIG. 1 (a), by feeding molten CaCl ₂ in the pump 5 into the anode compartment. The pump pressure is applied to the anode 1 side electrolytic bath, whereby the anode chamber side is maintained in a pressurized state with respect to the cathode chamber side. That is, this is an example in which the pressurized state by (1c) is maintained, and a pump is used as the means.

If a centrifugal pump made of a material resistant to high-temperature molten CaCl ₂ or other molten salt to be handled is used as the pump, the pump pressure can be applied to the electrolytic bath simultaneously with the supply of the electrolytic bath. .

In this case, the bath surface level of the anode 1 side electrolytic bath is maintained higher than the bath surface level of the cathode 2 side electrolytic bath by feeding molten CaCl ₂ into the anode chamber with the pump 5. That is, the pressurized state is maintained by (1a), which will be described later.

  In this way, by maintaining the anode chamber side in a pressurized state, a one-way bath flow from the anode chamber to the cathode chamber is formed, and the transition of Ca generated in the cathode 2 to the anode chamber side is hindered. , No back reaction occurs.

  The electrolytic cell shown in FIG. 1 (b) is the same as the electrolytic cell shown in (a) with respect to the arrangement of the anode 1, the cathode 2 and the partition wall 3, but the anode chamber side is changed to the cathode chamber side. On the other hand, the means for maintaining the pressurized state is different.

  That is, in the example shown in FIG. 1 (b), the bath surface level of the cathode 2 side electrolytic bath is maintained lower than the bath surface level of the anode 1 side electrolytic bath. ”, The pressure in the gas phase above the bath surface of the electrolytic bath in the anode chamber is relatively higher than the pressure in the gas phase in the cathode chamber, as indicated by“ −pressure ”on the cathode side. Maintained. It is an example where the pressurized state by said (1b) is maintained. For example, the gas phase portion on the cathode chamber side may be in an atmospheric pressure state and the gas phase portion on the anode chamber side may be pressurized, or the gas phase portion on the anode chamber side may be in an atmospheric pressure state and the gas phase portion on the cathode chamber side may be in an atmospheric pressure state. The phase part may be in a reduced pressure state.

  Thus, in order to maintain the pressure in the gas phase portion in the anode chamber relatively higher than the pressure in the gas phase portion in the cathode chamber, for example, the anode chamber and the cathode chamber including the gas phase portion are When the cathode chamber side is set to atmospheric pressure, the gas phase part on the anode chamber side is pressurized by mechanical means such as a compressor, and the anode chamber side is set to atmospheric pressure. What is necessary is just to take measures, such as making the gaseous-phase part by the side of a cathode chamber into a pressure reduction state using a vacuum pump.

  Furthermore, in the example shown in FIG. 1B, the bath surface level of the anode 1 side electrolysis bath is higher than the bath surface level of the cathode 2 side electrolysis bath by adjusting the supply amount of the electrolysis bath to the anode chamber. Maintained. It is an example where the pressurized state by said (1a) is maintained.

  As a means for that, although not shown, a metering pump or a normal centrifugal pump (however, a liquid level meter is used in combination) can be cited as an example. In other words, there are a method of feeding the electrolyte at a required flow rate using a metering pump, a method of feeding a liquid level meter to the electrolytic bath and feeding the electrolyte using the pump while controlling the bath surface level, etc. Can be used. In the latter case, the pump for applying the pump pressure can be shared as a pump for simultaneously feeding the electrolyte into the anode chamber. An example is the pump 5 in FIG.

  Also in the electrolytic cell shown in FIG. 1 (b), since a one-way bath flow from the anode chamber to the cathode chamber is formed, the transition of Ca generated in the cathode 2 to the anode chamber side is hindered, and the back reaction occurs. Is prevented.

  FIG. 2 is a longitudinal sectional view schematically showing another configuration example of the electrolytic cell of the present invention. Both (a) and (b) are cylindrical electrolytic cells (representing a surface including the central axis).

  The electrolytic cell shown in FIG. 2A is similar to the electrolytic cell shown in FIG. 1B, in which a cylindrical anode 1 is arranged at the center, and the entire inner surface of the outer peripheral part constitutes the cathode 2. . A partition wall 3 is provided between the anode 1 and the cathode 2. The difference from the electrolytic cell shown in FIG. 1 (a) or (b) is that the electrolytic bath is supplied to the anode chamber from above.

In the example shown in FIG. 2A, since the molten CaCl ₂ is fed into the anode chamber by the pump 5, the pump pressure is applied to the anode-side electrolytic bath. Thereby, the bath surface level of the anode 1 side electrolytic bath is maintained higher than the bath surface level of the cathode 2 side electrolytic bath. Therefore, the migration of Ca generated at the cathode 2 to the anode chamber side is hindered, and back reaction does not occur.

  The electrolytic cell shown in FIG. 2 (b) has the same configuration as the electrolytic cell shown in FIG. 2 (a), but instead of applying pump pressure to the anode-side electrolytic bath, The pressure is maintained relatively higher than the pressure in the gas phase portion of the cathode chamber, and at the same time, by adjusting the supply amount of the electrolytic bath to the anode chamber, the bath surface level of the cathode 2 side electrolytic bath is adjusted to the anode 1 side electrolysis. Maintained below the bath level of the bath.

  Therefore, also in this electrolytic cell, a one-way bath flow from the anode chamber to the cathode chamber is formed, and the transition of Ca generated at the cathode 2 to the anode chamber side is prevented, so that back reaction is prevented.

  FIG. 3 is a longitudinal sectional view schematically showing still another structural example of the electrolytic cell of the present invention, and both (a) and (b) are fluidized electrolytic cells having flat-plate electrodes.

  In the electrolytic cell shown in FIGS. 3A and 3B, a flat plate-like anode 6a and cathode 7 which are long in the vertical direction are arranged in parallel with a partition wall 8a interposed therebetween. There is an opening below the partition wall 8a, and conductivity between both electrodes is ensured.

In (a) of FIG. 3, an electrolytic bath (for example, molten CaCl ₂ ) is supplied from below the electrolytic cell, while in (b), it is supplied from the upper side of the electrolytic cell and electrolyzed. Chlorine 4 is generated on the anode 6a side of the electrolytic cell, and Ca is generated on the cathode 7 side. The produced Ca moves upward in the cathode chamber together with the bath flow, and is extracted in the direction indicated by the white arrow as molten CaCl ₂ containing Ca at a high concentration. Also in flow electrolytic cell having an electrode of the flat plate type, the supply rate of the molten CaCl ₂ to the cathode chamber, electrolysis conditions, by adjusting the bath temperature and the like, can be obtained Ca as a melt or solid It is.

In the electrolytic cell shown in FIGS. 3 (a) and 3 (b), a weir 9 is provided at the electrolyte outlet of the cathode chamber, and molten CaCl supplied from the lower side of the electrolytic cell or from the side of the upper part of the electrolytic cell. _By discharging ₂ from the weir 9, the bath surface level of the cathode 7 side electrolytic bath is maintained lower than the bath surface level of the anode 6a side electrolytic bath. This is a state in which there is a head difference of h between the anode 6a side electrolytic bath and the cathode 7 side electrolytic bath. It is an example where the pressurized state by said (1a) is maintained.

Therefore, a one-way bath flow from the anode chamber to the cathode chamber is formed, and the transition of Ca generated at the cathode 2 to the anode chamber side is prevented, so that no back reaction occurs. Incidentally, the chlorine produced at the anode 6a is so emerge as Cl _2, it is not able to penetrate into the cathode compartment.

  FIG. 4 is a longitudinal sectional view schematically showing another configuration example of the fluidized electrolytic cell. In each of the electrolytic cells (a) and (b), as in the electrolytic cell shown in FIG. 3, the flat plate-like anode 6a and the cathode 7 are arranged in parallel with the partition wall 8b interposed therebetween. 3 is different from the electrolytic cell shown in FIG. 3 in that a partition wall 8b provided with a large number of small holes (not shown) that can pass therethrough is used.

  In each of the electrolytic cells shown in FIGS. 4 (a) and 4 (b), a weir 9 is provided at the electrolyte outlet of the cathode chamber, and the bath level of the cathode 7 side electrolytic bath is the bath of the anode 6a side electrolytic bath. It is kept below the surface level. Furthermore, in the electrolytic cell of FIG. 4 (a), the pressure in the gas phase part of the anode chamber is maintained relatively higher than the pressure in the gas phase part of the cathode chamber, and in the electrolytic cell of FIG. The pump pressure is applied to the electrolytic bath. Therefore, in any of the electrolytic cells shown in FIGS. 4A and 4B, the migration of Ca produced at the cathode 7 to the anode chamber side is prevented, and no back reaction occurs.

  FIG. 5 is a longitudinal sectional view schematically showing still another configuration example of the fluidized electrolytic cell. In both electrolytic cells (a) and (b), a flat cathode 7 is arranged at the center, and flat anodes 6a and 6b are arranged on both sides in parallel with the cathode 7 with a partition wall 8b interposed therebetween. . Note that the anode chamber on the anode 6a side and the anode chamber on the anode 6b side are in communication with each other although not shown in FIG.

  Also in the electrolytic cell shown in FIGS. 5 (a) and 5 (b), a weir 9 is provided at the electrolyte outlet of the cathode chamber, and the bath surface level of the cathode 7 side electrolytic bath is higher than the bath surface level of the anode 6a side electrolytic bath. Is also kept low. Further, in the electrolytic cell of FIG. 5 (a), the pump pressure is applied to the electrolytic bath on the anode 6b side, and in the electrolytic cell of 5 (b), the gas phase part of the anode chamber on the anode 6a side. Is maintained relatively higher than the pressure in the gas phase portion of the cathode chamber. Therefore, in any of the electrolytic cells shown in FIGS. 5A and 5B, Ca generated at the cathode 7 does not shift to the anode chamber side.

  FIG. 6 is a longitudinal sectional view schematically showing still another configuration example of the fluidized electrolytic cell. Both the electrolytic cells (a) and (b) have a configuration similar to the electrolytic cell shown in FIG. 5, except that the electrolytic bath is supplied to the anode chamber only on the anode 6a side, It is different in that it is performed from above.

  Also in the electrolytic cell shown in FIGS. 6 (a) and 6 (b), a weir 9 is provided at the electrolyte outlet of the cathode chamber, and the bath surface level of the cathode 7 side electrolytic bath is higher than the bath surface level of the anode 6a side electrolytic bath. Is also kept low. Further, in the electrolytic cell of FIG. 5 (a), the pump pressure is applied to the electrolytic bath on the anode 6a side, and in the electrolytic cell of 5 (b), the gas phase part of the anode chamber on the anode 6a side. Is maintained relatively higher than the pressure in the gas phase portion of the cathode chamber. Therefore, in any of the electrolytic cells shown in FIGS. 6A and 6B, the migration of Ca produced at the cathode 7 to the anode chamber side is hindered.

  In the electrolytic cell of the present invention, if a porous ceramic body is used as the diaphragm or partition wall of the electrolytic cell, the effect of preventing Ca generated on the cathode side from entering the anode side is further improved.

As the diaphragm, for example, a porous ceramic body containing yttria (Y ₂ O ₃ ) can be used. A porous ceramic body obtained by firing yttria has a selective permeability that allows Ca and chlorine ions dissolved in an electrolytic bath (for example, molten CaCl ₂ ) to pass but does not allow metal Ca to pass therethrough. It has excellent calcium reduction resistance that is not reduced even by Ca having a reducing power, and is suitable as a diaphragm.

  If an electrolytic cell in which such a diaphragm is provided between the anode and the cathode is used, it effectively acts to suppress the inflow of Ca generated on the cathode chamber side to the anode chamber side. Since the pressure is maintained with respect to the side and Ca does not move to the anode chamber side, back reaction does not occur and electrolysis can be performed with high current efficiency.

As described above, a mesh can be used as the diaphragm, but for example, a metal mesh can also be used. The metal net is advantageous in that it is less expensive than a porous ceramic body and is not easily damaged. The metal mesh is coarser than the porous ceramic body, and the metal Ca easily passes through. However, in the electrolytic cell of the present invention, the anode chamber side is maintained in a pressurized state with respect to the cathode chamber side, and the Ca anode Since the transition to the chamber side is hindered, the metal net can be used as a diaphragm. As a material of the metal net, it is necessary not to be dissolved in a high-temperature electrolytic bath, and in the case of molten CaCl ₂ , iron, stainless steel, titanium, or the like can be used. Further, the above-described wire stretched vertically can be used in the same manner as the metal net.

  Instead of the diaphragm, a partition configured to allow the molten salt to flow may be used. The partition wall itself does not allow molten salts such as Ca and chlorine ions as well as metal Ca, but by providing slits or holes through which molten salt can pass in a part of the partition wall, electrolysis is possible, while metal Ca The back reaction can be suppressed by restricting the passage of the air to some extent.

  Each of the electrolytic cells of the present invention shown in FIGS. 1 to 6 has characteristics. Which one of them is used depends on the type of electrolytic bath, the fluidity and solubility of ions of the metal to be manufactured, the anode. It may be determined appropriately in consideration of the ease of gas generation on the surface, the performance of the partition walls, the layout of the entire apparatus, and the like.

  The metal production method of the present invention uses the above-described electrolytic cell, uses an alkali metal, alkaline earth metal or rare earth metal halide produced by an electrolysis method as an electrolytic bath, and sets the anode chamber side to the cathode chamber side. In this method, electrolysis is performed while maintaining a pressurized state.

  As described above, the metal to be manufactured is Na, Li, Be, Ca, Mg, La, Ce, and the like. Each metal can be produced by electrolyzing a molten salt containing a chloride or fluoride of these metals using the electrolytic cell of the present invention.

For example, in the case where metal calcium is produced by using a calcium salt or a molten salt containing calcium salt as an electrolytic bath, which is an embodiment of the metal production method of the present invention, the electrolytic cell of the present invention is taken as an example. Has a configuration as described above, a one-way flow rate is given to the molten CaCl ₂ supplied into the electrolytic cell. Molten CaCl ₂ is electrolyzed while passing upward in the cathode chamber, and Ca is generated, so that molten CaCl ₂ enriched in Ca can be extracted from above the electrolytic cell.

Furthermore, by adjusting the supply rate of the molten CaCl ₂ to the cathode chamber, the electrolysis conditions, etc., Ca is generated to an extent exceeding the saturation concentration, and the molten CaCl ₂ containing the metal Ca in a molten state or a precipitated state is electrolyzed. It is also possible to extract from the upper part of the tank, and Ca can be obtained as a melt or solid by appropriately setting the temperature of the electrolytic bath. Since the molten metal Ca has a specific gravity smaller than that of the molten CaCl _2, it can be easily recovered by specific gravity separation.

In the electrolytic cell of the present invention, during the electrolysis, the anode chamber side is maintained in a pressurized state with respect to the cathode chamber side, so that a unidirectional bath flow from the anode chamber to the cathode chamber is formed and generated at the cathode. Migration of Ca to the anode chamber side is hindered. Therefore, back reaction does not occur, and it is possible to obtain molten CaCl ₂ or metallic Ca enriched in Ca with high current efficiency.

  When the electrolytic cell of the present invention is used, the anode chamber side can be maintained in a pressurized state with respect to the cathode chamber side during the electrolysis, and Ca generated on the cathode side can be prevented from entering the anode side. This can prevent back reaction and maintain high current efficiency.

  In addition, if this electrolytic cell is used, alkali metal, alkaline earth metal or rare earth metal such as Na, Ca, Mg, La, etc. produced by the electrolysis method are continuously produced while maintaining high current efficiency. Is possible.

  Therefore, the electrolytic cell and metal production method of the present invention can be effectively used in the purification, production or related fields of these metals.

It is a longitudinal cross-sectional view which shows typically the structural example of the electrolytic cell (cylindrical shape) of this invention. It is a longitudinal cross-sectional view which shows typically the other structural example of the electrolytic vessel (cylindrical shape) of this invention. It is a longitudinal cross-sectional view which shows typically the structural example of the electrolytic cell (flat plate type) of this invention. It is a longitudinal cross-sectional view which shows typically the other structural example of the electrolytic vessel (flat plate type) of this invention. It is a longitudinal cross-sectional view which shows typically the further another structural example of the electrolytic cell (flat plate type) of this invention. It is a longitudinal cross-sectional view which shows typically the further another structural example of the electrolytic cell (flat plate type) of this invention.

Explanation of symbols

1: Anode
2: Cathode 3, 3a, 3b: Partition
4: Chlorine 5: Pump
6a, 6b: anode
7: Cathode 8a, 8b: Partition wall
9: Weir

Claims (10)

An electrolytic bath having an anode and a cathode arranged vertically in an electrolytic cell, an electrolytic bath supply port for supplying an electrolytic bath between the anode and the cathode, and a metal concentration generated by electrolysis of the electrolytic bath is increased. A fluidized electrolytic cell provided with an electrolytic bath outlet for extracting the electrolytic bath out of the electrolytic cell;
An electrolytic cell comprising means capable of maintaining the anode chamber side where the anode is disposed in a pressurized state relative to the cathode chamber side where the cathode is disposed during electrolysis.   2. The electrolytic cell according to claim 1, wherein the cathode-side electrolytic bath and the anode-side electrolytic bath are separated by a partition wall, a diaphragm, a net, and the like.   The electrolytic cell according to claim 1 or 2, wherein the pressurized state is a state in which the bath surface level of the cathode side electrolytic bath is maintained lower than the bath surface level of the anode side electrolytic bath.   4. The electrolytic cell according to claim 3, wherein the difference in bath level between the cathode side electrolytic bath and the anode side electrolytic bath is maintained by providing a weir in the cathode chamber.   The electrolytic cell according to claim 3, wherein the difference in bath level between the cathode side electrolytic bath and the anode side electrolytic bath is maintained by adjusting the supply amount of the electrolytic bath to the anode chamber.   3. The electrolytic cell according to claim 1, wherein the pressurized state is a state in which the pressure in the gas phase portion in the anode chamber is maintained relatively higher than the pressure in the gas phase portion in the cathode chamber. .   The electrolytic cell according to claim 1 or 2, wherein the pressurized state is a state in which a pump pressure is applied to the anode-side electrolytic bath.   The electrolytic cell according to claim 2, wherein a porous ceramic body is used as a diaphragm or partition wall of the electrolytic cell.   The electrolytic cell according to any one of claims 1 to 8, wherein the electrolytic bath is an alkali metal, alkaline earth metal or rare earth metal halide produced by an electrolysis method, and the anode chamber side is the cathode chamber side. A method for producing a metal, characterized in that electrolysis is performed while maintaining a pressurized state.   10. The method for producing a metal according to claim 9, wherein metallic calcium is obtained by using calcium salt or a molten salt containing calcium salt as an electrolytic bath.

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