Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
  • C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
  • C25C3/02—Electrolytic production, recovery or refining of metals by electrolysis of melts of alkali or alkaline earth metals
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
  • C25C7/00—Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells
  • C25C7/005—Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells of cells for the electrolysis of melts
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
  • C25C7/00—Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells
  • C25C7/04—Diaphragms; Spacing elements

Definitions

• the present invention relates to an electrolytic device for obtaining a reducing metal from a metal chloride by molten salt electrolysis, and an electrolytic method thereof.
• Metallic titanium has been widely used in conventional aircraft materials and parts, and in recent years, development of applications has progressed, and it is widely used in construction materials, roads, sports goods and the like.
• elemental metallic titanium is manufactured by the Kroll method in which titanium tetrachloride is reduced with molten magnesium to obtain sponge titanium, and manufacturing costs have been reduced by stacking various improvements.
• the crawling method is a notching process that repeats a series of operations discontinuously, the efficiency is limited.
• titanium metal is recovered from the reaction system after the electrolytic reaction, and then calcium chloride by-produced in the electrolytic reaction is dissolved in calcium chloride to carry out molten salt electrolysis. Recover metallic calcium and reuse it in the production process of metallic titanium.
• Patent document l WO99Z064638
• Patent Document 2 Japanese Patent Application Laid-Open No. 2003-129268
• Patent Document 3 Japanese Patent Application Laid-Open No. 2003-306725
• Patent Document 4 US 3226311
• the present invention has been made in view of the above situation, and is an apparatus and method for producing a reducing metal used to reduce, for example, an acid oxide or chloride of metal titanium.
• the present invention provides a molten salt electrolytic apparatus for efficiently producing a reducing metal by molten salt electrolysis, a method of electrolysis of a reducing metal using the same, and a method of producing a high melting point metal using the reducing metal.
• the present inventors have intensively studied in view of the strong situation, it has been found that high current efficiency can be achieved by arranging partition walls which independently surround the periphery of the anode and the cathode that make up the molten metal electrolytic bath of reducing metals. It has been found that reducing metals can be produced while maintaining the above, and the present invention has been completed.
• the present invention relates to a molten metal salt electrolyzing apparatus for a reducible metal provided with an electrolytic cell filled with a molten metal salt containing a reducible metal chloride and in which the anode and the cathode are immersed. It is characterized in that the surrounding anode side partition wall and the cathode side partition wall surrounding the periphery of the cathode are disposed.
• the anode side partition and the cathode side partition have openings through which molten salt can flow. According to such a configuration, while the diffusion of chlorine gas and reducing metal is suppressed by the partition wall, the efficiency of the molten salt electrolytic reaction is lowered by the ability to circulate the molten salt through the opening. Can be suppressed.
• the anode-side partition extends to the bottom of the electrolytic cell, and the anode-side partition is preferably made of a porous body. According to such a configuration, since the chlorine gas generated becomes bubbles, it floats on the surface of the electrolytic bath without passing through the porous body, while the electrolytic bath can pass through the porous body, and therefore, chloride gas is generated. The reaction can be advanced by contact between the ion and the anode.
• the anode side partition be made of metal oxide, metal nitride or metal carbide
• the cathode side partition be made of metal, metal nitride or metal carbide.
• the method for producing a reducible metal according to the present invention is characterized by using the above-described molten salt electrolytic device.
• molten salt electrolyzer of the present invention By using the molten salt electrolyzer of the present invention, a high purity, reducible metal can be efficiently produced while maintaining high current efficiency.
• the present invention is characterized in that a salt of a refractory metal selected from titanium, zirconium, tantalum and niobium is reduced by the reducing metal produced by the above-mentioned method.
• FIG. 1 is a schematic cross-sectional view showing first and second embodiments of a molten salt electrolysis apparatus of the present invention.
• FIG. 2 is a schematic cross-sectional view showing a third embodiment of the molten salt electrolysis apparatus of the present invention.
• FIG. 3 is a schematic cross-sectional view showing a fourth embodiment of the molten salt electrolysis apparatus of the present invention.
• FIG. 4 is a schematic cross-sectional view showing a fifth embodiment of the molten salt electrolysis apparatus of the present invention.
• FIG. 1 shows a configuration example of a preferred molten salt electrolytic device for carrying out the present invention.
• any combination can be used as the combination of the electrolytic bath used in the present embodiment and the reducing metal to be produced, calcium chloride in the electrolytic bath and calcium metal to be produced are metallic calcium.
• the case where metallic calcium is recovered in a solid state by setting the temperature of the electrolytic bath to the melting point of metallic calcium or less (first embodiment) will be described as an example.
• the molten salt electrolyzer la is constructed by filling an electrolytic bath 12 with molten calcium and calcium in an electrolytic cell 11, and an anode 21 and a cathode 22 are disposed so as to be immersed in the electrolytic bath 12. .
• the anode side partition wall 31 is disposed so as to surround the periphery of the anode 21, and the cathode side partition wall 32 is disposed so as to surround the periphery of the cathode 22.
• the anode side partition 31 is made of a porous body, and the electrolytic bath 12 can move by permeation and diffusion on the side of the anode 21 surrounded by the anode side partition 31 and the outside.
• the cathode side partition 32 is made of a dense substance, and the electrolytic bath 12 can not permeate and diffuse, but the cathode side partition 32 surrounds the cathode 22 near the lower side of the cathode 22 Part 33 is provided.
• the molten salt electrolytic tank 1 is heated to a temperature above the melting point of calcium chloride by a heating means (not shown) to bring the electrolytic bath 12 into a molten state.
• a predetermined DC voltage is applied between the anode 21 and the cathode 22 to start the molten salt electrolysis of the electrolytic bath 12.
• the chloride ions contained in the electrolytic bath 12 pass through the anode side partition wall 31 and are attracted to the anode 21 to give electrons to the electrode to produce chlorine gas 41.
• the produced chlorine gas 41 is recovered and transferred to another process not shown, such as a chlorination process, for example, and reused separately.
• molten salt electrolyzer la having the above configuration, bubbles of chlorine gas 41 generated at anode 21 are prevented from being blocked by anode side partition wall 31 and diffused in the direction of cathode 22, and most of them are Floats in the electrolyte surface direction.
• a part of the solid metal calcium formed at the cathode 22 is dissolved in the electrolytic bath 12, it is suppressed by the cathode side partition wall 32 and diffusion in the direction of the anode 21 is suppressed.
• the partition walls surrounding the electrode diffuse the generated chlorine gas and metallic calcium and contact with each other to prevent the reverse reaction, thereby improving the efficiency of molten salt electrolysis.
• the metallic calcium produced by the electrolysis is immediately dissolved in the electrolytic bath present on the inner side of the cathode side partition wall 32 immediately after formation, and the metallic calcium concentrated layer 42 containing calcium chloride is obtained.
• the metal calcium enrichment layer 42 is appropriately extracted and transferred to a titanium reduction step (not shown) and used.
• molten salt electrolyzer 1 of the second embodiment of the above configuration bubbles of chlorine gas 41 generated at the anode 21 are blocked by the anode side partition wall 31 in the same manner as the first embodiment.
• the diffusion in the direction 22 is suppressed, and most of the surface floats in the electrolyte surface direction.
• metallic calcium produced at the cathode 22 is inhibited by the cathode side partition wall 32 and diffused in the direction of the anode 21. As a result, it is suppressed that chlorine gas and metallic calcium cause reverse reaction, so the efficiency of molten salt electrolysis is improved.
• the electrolytic cell 11 is preferably made of a material that can withstand the high temperature at the time of operation and is made of a material that does not easily react with molten salt calcium or molten metal calcium. Specifically, metal titanium or tantalum may be used. Is preferably composed of niobium.
• the temperature of the electrolytic bath 12 differs depending on whether the metallic calcium is recovered in the molten state or in the solid state.
• it is preferable to conduct molten salt electrolysis in a temperature range higher than the melting point of metallic calcium. Specifically, it is 5 ° C. to 50 ° C. higher than the melting point of metallic calcium. High temperature, preferably to select the temperature range. Since the melting point of metal calcium is 845 ° C, the temperature of the electrolytic bath is 850 ° C to 895 ° C. In addition, the range of 5 ° C. to 20 ° C. is considered to be more preferable in consideration of the cost required for heating and the evaporation of calcium chloride. Since the melting point of calcium chloride is 780 ° C., which is lower than the melting point of metallic calcium, so long as metallic calcium is held in the molten state, calcium chloride is also held in the molten state.
• the temperature of the electrolytic bath is It is preferable to keep the temperature range above the melting point of calcium metal and below the melting point of metallic calcium. Specifically, it is below 845.degree. C., which is the melting point of metallic calcium, and above the melting point of calcium chloride. It becomes a temperature range. However, it is preferable to electrolyze at a temperature just above the melting point of calcium chloride since metallic calcium produced at the cathode dissolves in calcium chloride and is easy to diffuse. It is preferable to electrolyze at 785 degreeC-800 degreeC specifically ,.
• the electrolytic bath can lower the melting point of the electrolytic bath by using not only a single bath of calcium chloride but also a mixed salt with potassium chloride or calcium fluoride.
• the electrolysis temperature can also be lowered compared to the case of a calcium chloride single bath, and the precipitation of solid metallic calcium can be facilitated.
• the addition of about 5 to 20 mol% of sodium chloride or potassium fluoride with respect to sodium chloride can exhibit sufficient effects.
• the anode is disposed so as to be immersed in the electrolytic bath, and chlorine gas is generated by the electrolysis of calcium chloride constituting the electrolytic bath. Since the temperature of the electrolytic bath is a high temperature around 800 ° C., the anode is exposed to high temperature chlorine gas and calcium chloride. For this reason, it is preferable from the industrial point of view that it is preferable to use a material resistant to high temperature chlorine gas and molten salt, and graphite is preferable. Graphite is relatively inexpensive, easy to process, and has excellent corrosion resistance to molten salts and chlorine gas at high temperatures, and is suitable for the anode of the present invention.
• the cathode is disposed in the electrolytic bath so as to deposit metallic calcium by electrolysis of calcium chloride.
• metallic calcium exhibits reducibility, it can be made of, for example, carbon steel or stainless steel, as long as it is a material resistant to molten calcium chloride and excellent in electrical conductivity.
• the anode side partition wall is provided to suppress the reverse reaction that chlorine gas generated at the anode reacts with metallic calcium generated at the cathode and returns to calcium chloride, and should be placed so as to surround the periphery of the anode. Is preferred. However, if the external electrolytic bath partitioned by the anode side partition can not move to the inside of the anode side partition, the electrolytic reaction can not be continued. Therefore, in the case of mounting the anode side partition wall having no opening as shown in FIG. 1, although the chlorine gas does not diffuse in the anode side partition wall, the electrolytic bath is made of a porous body which can move. It is preferable to
• the material of the porous body is preferably selected from metal oxides, metal nitrides or metal carbides which have corrosion resistance to chlorine gas and molten salt.
• the metal oxide is alumina, silica, zirconia, magnesia, or a composite that also has a ceramic power
• the metal nitride is silicon nitride, boron nitride, titanium nitride, zirconium nitride, or nitrided. It is preferred to select and configure the tantalum force. Furthermore, it is preferable to select and configure carbon carbide, boron carbide, titanium carbide, zirconium carbide, and tantalum carbide as metal carbides.
• the porosity of the porous body is preferably in the range of 5 to 30%.
• the cathode side partition by disposing such a partition which is preferably arranged to surround the periphery of the cathode, it is possible to effectively suppress the diffusion of metallic calcium generated at the cathode.
• the cathode side partition can be made of a porous body as the anode side partition, but chlorine gas is bubbled and floats in the air to be removed from the system, while metal calcium is removed. Since it floats in the electrolytic bath, it may permeate and diffuse toward the anode. Therefore, it is preferable to use a material as dense as possible.
• the cathode side partition wall is made of ceramics, it is often reduced and corroded by molten calcium, so it is preferable to be made of metal, metal nitride or metal carbide.
• the metal is preferably corrosion resistant stainless steel, titanium, niobium, tantalum, and metal nitride is preferably silicon nitride, boron nitride, titanium nitride, zirconium nitride, or tantalum nitride.
• metal carbides silica carbide, boron carbide,
• titanium carbide, zirconium carbide and tantalum carbide also constitute.
• the cathode-side partition wall is preferably as compact as possible in order to suppress the diffusion of metallic calcium generated in the cathode.
• the cathode side partition is provided with an opening in order to facilitate the movement of the electrolytic bath.
• the cathode side partition opening is preferably disposed at a distance of 10 mm or more below the lower end of the cathode. If the cathode side partition opening is arranged within a range of 10 mm below the tip of the electrode, the metal calcium diffused downward to the bath surface is not preferable because the calcium calcium is diffused to the outside of the cathode side partition from the opening. Further, when the cathode side partition wall is a cylinder, it is more preferable to provide a plurality of openings.
• a concentrated layer of metallic calcium in which metallic calcium produced by electrolytic reaction is dissolved alone or in calcium chloride is formed.
• the metal force concentrated layer can be used, for example, as a direct reducing agent for tartaric acid waste or titanium salt waste, by rapidly extracting the electrolytic cell force to another container.
• FIG. 2 shows an electrolyzer lb in another preferred embodiment (third embodiment) according to the present invention.
• the tank partition 34 is provided between the anode-side partition 31 and the cathode-side partition 32.
• a tank partition opening 35 to which the electrolytic bath 12 can move, in the tank partition 34 arranged to be immersed in the electrolytic bath 12.
• FIG. 3 shows an electrolytic device lc in a preferred embodiment (fourth embodiment) in which the present invention is applied to a real machine.
• various supply pipes and withdrawal pipes are additionally arranged in the third embodiment.
• the metallic calcium enrichment layer extraction pipe 53 for extracting the metal calcium enrichment layer 42 and sending it to the next process and the electrolytic bath extraction pipe 54 are added. It is arranged.
• the anode side partition wall 31 in the first and second embodiments is changed in shape to cover the whole of the anode 21.
• a chlorine gas extraction pipe 52 is provided which can extract the chlorine gas 41 generated at the anode 31 out of the system without leakage.
• an anode side partition opening 36 is provided at the lower end of the anode side partition wall 31 (52).
• the anode side partition wall 31 be made of a dense metal oxide, metal nitride or metal carbide in order to avoid permeation and diffusion of the electrolytic bath 12. It is more preferable to use metal nitride.
• the heights of the openings 36, 35 and 33 for flowing the electrolytic bath provided in each of the anode side partition 31 and the tank partition 34 and the cathode side partition 32 are arranged to be different from each other in the same step. Is preferable. With such an arrangement of the openings, the flow of the electrolytic bath 12 up to the anode 21 meanders up and down even if the metal calcium or metal calcium enrichment layer 42 generated at the cathode 22 reaches the openings. Reverse reaction with chlorine gas generated at the anode can be effectively avoided.
• FIG. 4 shows an electrolyzer Id in another preferred embodiment (fifth embodiment) according to the present invention.
• This embodiment comprises an electrolytic cell 11, an anode 21, a cathode 22, a partition wall 37 and an electrolytic bath 12, and the basic specifications are the same as those of the first to fourth embodiments.
• the anode-side partition 31 and the cathode-side partition 32 in the first to fourth embodiments are bonded to each other and configured as one partition 37, and the partition 37 is a ceramic layer on the anode side.
• the fourth embodiment differs from the first to fourth embodiments in that it is composed of a clad material composed of 37a and a metal layer 37b on the cathode side.
• the ceramic layer 37 a and the metal layer 37 b constituting the partition wall 37 be made of the same material as the material constituting the anode side partition wall 31 and the cathode side partition wall 32 described above. Furthermore, the ceramic layer 37a is more preferably in the form of metal oxide. When the ceramic layer 37a is formed of metal nitride, the metal layer 37b is not necessarily required, and can be formed of a single substance of the ceramic layer 37a.
• the electrical resistance between the anode 21 and the cathode 22 is the same as in the above embodiment in which a plurality of partitions are immersed. It becomes smaller than that. As a result, less power is required to electrolyze molten salt, and metal calcium It is possible to reduce the basic unit consumption of electricity.
• metallic titanium can be produced by using the metallic calcium produced by the above method as a reducing agent for titanium tetrabasic.
• Metal zirconium metal tantalum or metal niobium can also be efficiently produced by using titanium tetrachloride as a reducing agent of zirconium tantalum or niobium chloride instead of titanium tetrachloride.
• Electrolyzer Titanium crucible
• Example 2 Under the same conditions as in Example 1 except that the temperature of the electrolytic bath was set to 800 ° C., molten salt electrolysis was performed under the temperature conditions in which a solid metal salt precipitates on the cathode. As a result, solid metallic calcium was deposited on the surface of the cathode. Compared with the theoretical amount of precipitated metal calculated from the amount of current The current efficiency was 85%. Analysis of the precipitated metallic calcium revealed that the purity was 90%.
• the temperature of the electrolytic bath was set to 800 ° C., and the other conditions were the same as in Example 1, and molten salt electrolysis of calcium chloride was performed for 5 hours.
• the current efficiency obtained by comparing the amount of metallic calcium recovered by molten salt electrolysis and the amount-of-current-force calculation was calculated to be 80%.
• analysis of the recovered metallic calcium revealed that the purity was 90%.
• Example 1 molten salt electrolysis of sodium chloride was carried out under the same conditions under the same conditions except that only the cathode side partition wall 32 was used. The current efficiency calculated in comparison with the theoretical amount of precipitating metal is also calculated at 25%.
• the molten salt electrolysis of sodium chloride was conducted under the same conditions as in Example 1 except that only the anode side partition wall 31 was used, and the metal calcium recovered by the molten salt electrolysis and the amount of electric current were used.
• the current efficiency calculated in comparison with the theoretical amount of precipitating metal also calculated is 40% at last.
• the present invention exhibits an effect that metal calcium can be efficiently generated and recovered by molten salt electrolysis of metal salt, particularly calcium salt. is there. Furthermore, reduction of chloride of high melting point metal can be carried out using the produced calcium metal.

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• 2006
  • 2006-06-21 AU AU2006293385A patent/AU2006293385A1/en not_active Abandoned
  • 2006-06-21 JP JP2007536407A patent/JPWO2007034605A1/ja active Pending
  • 2006-06-21 US US12/067,670 patent/US20090152104A1/en not_active Abandoned
  • 2006-06-21 WO PCT/JP2006/312436 patent/WO2007034605A1/ja active Application Filing
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