Electrode replacement device, molten salt electrolysis device, and method for manufacturing titanium-based electrodeposits

Abstract

To provide an electrode exchange device capable of performing a good exchange of electrode plates in electro-refining a crude titanium-based material containing Ti, Al and O, and to provide a molten salt electrolysis device and a method for producing the titanium-based electrodeposited material.SOLUTION: An electrode exchange device 1 includes: electrode housing container 2 used for replacing electrodes 61 in electrolytic refining in which a crude titanium-based material in an anode 61a is dissolved in a molten salt bath Bm inside an electrolytic bath 51 to deposit a purified titanium-based material in a cathode 61b, wherein the crude titanium-based material contains Ti, Al, and O and is conductive, the electrodes include a portion where the electrode plates 62 that function as either an anode or a cathode are arranged alternately, and the electrode housing container has an opening 2a that can be hermetically connected to an aperture 51c of the electrolytic bath 51 and stores the electrode plates inside; an electrode holding mechanism 3 capable of holding the electrode plates and moving them between the electrode housing container and the electrolytic bath while the electrode plates are connected to the aperture of the electrode housing container and the electrolytic bath; and a vessel opening / closing mechanism 4 that opens and hermetically closes the aperture of the electrode housing container.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to an electrode replacement device, a molten salt electrolytic device, and a method for producing titanium electrodeposited material, used for electrode replacement in electrolytic refining, in which crude titanium-based material is dissolved in a molten salt bath to deposit refined titanium-based material on the cathode. [Background technology]

[0002] Metallic titanium and titanium alloys are generally manufactured using methods based on the Kroll process, which is suitable for mass production. However, this method involves numerous steps, including the chlorination and reduction of titanium ore, as well as the crushing of sponge titanium ingots and the electrolysis of magnesium chloride, making it difficult to say that metallic titanium and titanium alloys can be manufactured efficiently and at low cost.

[0003] In contrast, electrolytic refining using molten salt electrolysis may allow for the easy production of titanium and titanium alloys.

[0004] As an example of this type of technology, Patent Document 1 describes a method for extracting titanium products from titanium ore, characterized by comprising the following steps: a step of mixing a chemical blend containing titanium ore and a reducing agent, wherein the ratio of the titanium ore to the reducing agent corresponds to a mass ratio of titanium oxide component in the titanium ore to the reducing metal in the reducing agent of 0.9 to 2.4; a step of heating the chemical blend to start an extraction reaction, wherein the chemical blend is heated at a rate of increase of 1°C to 50°C / min; and the chemical blend is heated at a reaction temperature of 1500 to 1800°C for a time between 5 minutes and 30 minutes. The steps include: maintaining the chemical blend at a certain temperature; cooling the chemical blend to a temperature lower than 1670°C; and separating the titanium product from the residual slag; and including the steps of: placing the titanium product into a reaction vessel having an anode, a cathode, and an electrolyte; heating the reaction vessel to a temperature of 600°C to 900°C to produce a molten mixture, applying an electrical differential between the anode and the cathode to deposit titanium ions on the cathode; and ending the electrical differential and cooling the molten mixture to produce a refined titanium product, wherein the surface area of ​​the refined titanium product is at least 0.1 m². 2 It states that it is " / g". [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2015-507696 [Overview of the project] [Problems that the invention aims to solve]

[0006] In electrolytic refining using molten salt electrolysis, a crude titanium-based material containing Ti, Al, and O and having conductivity is used as the anode in a molten salt bath in an electrolytic cell, and a voltage is applied between the anode and the cathode. As a result, the crude titanium-based material at the anode dissolves, and a refined titanium-based material with a higher purity than the crude titanium-based material is deposited at the cathode, thereby producing a titanium-based electrodeposited material.

[0007] In order to mass-produce titanium-based electrodeposits industrially, it is preferable to arrange electrode plates, each functioning as either an anode or a cathode, alternately. By using such plate-shaped electrodes, a wide electrodeposition surface can be secured for the cathode, where the refined titanium-based material is deposited, facing the anode.

[0008] Furthermore, in the electrolytic refining process described above, as molten salt electrolysis continues, the anode becomes difficult to use further due to reasons such as a decrease in the Ti content of the crude titanium-based material it contains, a relative increase in the Al and O content, and a resulting increase in electrical resistance. In addition, if molten salt electrolysis is continued, the refined titanium-based material deposited on the cathode will gradually grow. In particular, when the anode and cathode are arranged to reduce the distance between them in order to increase productivity by minimizing the effect of electrical resistance in the molten salt bath, a short circuit may occur in a relatively short period of time due to contact between the refined titanium-based material growing on the cathode and the anode, potentially making it impossible to continue molten salt electrolysis. For this reason, the duration of molten salt electrolysis cannot be extended very long.

[0009] Therefore, when mass-producing titanium-based electrodeposits, it is desirable to continue molten salt electrolysis for a certain period of time, then replace the electrode plates that have functioned as anodes and cathodes, and repeat this replacement process to continue producing titanium-based electrodeposits. When replacing the electrodes, it is necessary to avoid contact with the atmosphere as much as possible in order to suppress the oxidation of the high-temperature electrode plates and precipitates removed from the molten salt bath, and in particular the increase in oxygen content due to the oxidation of the refined titanium-based material deposited on the cathode electrode plate.

[0010] It is believed that no apparatus has been proposed to date that allows for the replacement of electrode plates during the electrolytic refining of crude titanium-based materials containing Ti, Al, and O as described above.

[0011] The object of this invention is to provide an electrode replacement device, a molten salt electrolytic device, and a method for producing titanium electrodeposits, which enable efficient replacement of electrode plates in the electrolytic refining of crude titanium-based materials containing Ti, Al, and O. [Means for solving the problem]

[0012] The electrode replacement device of this invention is used for replacing electrodes, including the anode and the cathode, in electrolytic refining in which a crude titanium-based material of the anode is dissolved in a molten salt bath inside an electrolytic cell and a refined titanium-based material is deposited on the cathode, wherein the crude titanium-based material contains Ti, Al and O and is conductive, and the electrode includes a portion in which electrode plates that function as either the anode or the cathode are arranged alternately, and the electrode replacement device comprises an electrode storage container having an opening that can be airtightly connected to the opening of the electrolytic cell and storing the electrode plates inside, an electrode holding mechanism that holds the electrode plates and can move the electrode plates between the electrode storage container and the electrolytic cell while they are connected at the opening between them, and a container opening and closing mechanism that opens and airtightly closes the opening of the electrode storage container.

[0013] Preferably, the electrode holding mechanism includes a holding rod provided for each electrode plate, extending vertically to suspend and hold each electrode plate, and a lifting plate located above the holding rods and outside the electrode storage container, to which each of the holding rods is attached.

[0014] In this case, the electrode replacement device preferably includes an electrical connection mechanism that electrically connects the power supply and the electrode plate, and the electrical connection mechanism preferably includes a conductor located outside the electrode storage container and connected to the power supply, and a conductor extending vertically parallel to the holding rod and connecting the electrode plate to the conductor.

[0015] The electrode exchange device is preferably disposed so as to cover the upper side of the electrode plate held by the electrode holding mechanism, moves together with the movement of the electrode plate by the electrode holding mechanism, and includes a shielding plate that shields the inside of the electrode storage container from the molten salt bath inside the electrolytic cell.

[0016] The electrode storage container may have a storage space with a certain volume.

[0017] Further, the electrode storage container may have a bellows wall portion that expands and contracts following the movement of the electrode plate between the inside of the electrode storage container and the inside of the electrolytic cell by the electrode holding mechanism, and a storage space that causes a change in volume as the bellows wall portion expands and contracts.

[0018] The electrode storage container may have a storage space that stores both the electrode plate that gives one of the polarities of the anode or the cathode and the electrode plate that gives the other polarity.

[0019] Further, the electrode storage container may have a plurality of divided storage containers that separately store the electrode plates that give one of the polarities of the anode or the cathode and the electrode plates that give the other polarity.

[0020] The electrode storage container preferably has a vent through which an inert gas can be supplied to the inside thereof.

[0021] The molten salt electrolysis device of this invention includes any one of the above electrode exchange devices, the electrolytic cell, and the electrodes, and the electrolytic cell has a cell opening / closing mechanism that opens and hermetically closes the opening of the electrolytic cell.

[0022] The electrolytic cell preferably has a temperature adjustment mechanism that is located on the bottom side of the electrode in a state where the electrode is disposed inside the electrolytic cell and adjusts the temperature of the molten salt bath.

[0023] The method for manufacturing a titanium-based electrodeposit of this invention includes an electrolysis step of performing electrolytic purification in a molten salt bath using the above-described molten salt electrolysis apparatus, dissolving the crude titanium-based material of the anode in the molten salt bath, and depositing the purified titanium-based material on the cathode.

Advantages of the Invention

[0024] According to the electrode replacement device of this invention, in the electrolytic purification of a crude titanium-based material containing Ti, Al, and O, the replacement of the electrode plates can be performed well.

Brief Description of the Drawings

[0025] [Figure 1] It is a cross-sectional view along the depth direction of a molten salt bath showing the electrode replacement device of one embodiment of this invention together with an electrolytic cell and electrodes. [Figure 2] It is a cross-sectional view similar to FIG. 1 showing the state where the electrodes are moved from the inside of the electrolytic cell to the inside of the electrode storage container in the electrode replacement device of FIG. 1. [Figure 3] It is a cross-sectional view taken along line III-III of FIG. 1. [Figure 4] It is a cross-sectional view along the depth direction of a molten salt bath showing the electrode replacement device of another embodiment together with an electrolytic cell and electrodes. [Figure 5] It is a cross-sectional view similar to FIG. 4 showing the state where the electrodes are moved from the inside of the electrolytic cell to the inside of the electrode storage container in the electrode replacement device of FIG. 4. [Figure 6] It is a plan view showing the electrode storage container and the container opening / closing mechanism of the electrode replacement device of still another embodiment together with an electrolytic cell and electrodes. [Figure 7] It is a plan view showing an example of the procedure for replacing electrodes using the electrode replacement device of FIG. 6. [Figure 8] It is a plan view showing the procedure following FIG. 7. [Figure 9] It is a plan view showing the procedure following FIG. 8. [Figure 10] It is a plan view showing the procedure following FIG. 9.

Modes for Carrying Out the Invention

[0026] Embodiments of this invention will be described in detail below with reference to the drawings.

[0027] (electrode exchange device) The electrode replacement device 1 illustrated in Figure 1 is used for replacing electrodes 61, including the anode 61a and cathode 61b, in electrolytic refining by molten salt electrolysis in an electrolytic cell 51.

[0028] This electrolytic refining process aims to obtain a refined titanium-based material with a higher purity than the crude titanium-based material. The crude titanium-based material contains Ti (titanium), Al (aluminum), and O (oxygen) and is electrically conductive, and is included in the composition of anode 61a as part or all of it. As shown in Figure 1, when a voltage is applied between anode 61a and cathode 61b with at least a portion of each immersed in the molten salt bath Bm, the crude titanium-based material of anode 61a dissolves, the refined titanium-based material is deposited on cathode 61b, and at least a portion of the impurities Al and O is removed. This makes it possible to produce titanium-based electrodeposits such as metallic titanium or titanium alloys as the refined titanium-based material. Details of the manufacturing method of titanium-based electrodeposits, including electrolytic refining, will be described later.

[0029] The electrolytic cell 51 used in electrolytic refining is, for example, a container-like structure made of steel or brick, with a cylindrical peripheral wall portion 51a, such as an elliptical or rectangular tube, sealed at the bottom portion 51b. Molten salt is stored inside to form a molten salt bath Bm. The electrolytic cell 51 is equipped with a cell opening / closing mechanism 52, such as a gate valve, which opens or closes the opening 51c on the upper side of the peripheral wall portion 51a. For example, the inner surface of a brick electrolytic cell 51 may be lined with steel or nickel.

[0030] Furthermore, the electrode 61, which is immersed in the molten salt bath Bm inside the electrolytic cell 51 during electrolytic refining, includes a portion in which electrode plates 62, each functioning as either an anode 61a or a cathode 61b, are arranged alternately.

[0031] By arranging the plate-shaped electrode plates 62 in this manner so that their main surfaces face each other, a large number of electrode plates 62 can be placed in a predetermined volume inside the electrolytic cell 51, and furthermore, molten salt electrolysis can be efficiently performed while maintaining a relatively short distance between electrodes over a wide surface. For example, although not shown in the diagram, if multiple cylindrical cathodes are arranged circumferentially inside a cylindrical anode, or if a single cylindrical or cylindrical cathode is arranged concentrically with the anode, the following problems arise and it is inefficient. In the former case, the refined titanium-based material deposited on the cathode concentrates on the cathode at locations with a short predetermined distance between electrodes on their opposing surfaces, and in the latter case, the initial distance between electrodes is long, the electrical resistance of the electrolytic bath increases and power consumption increases, and as the refined titanium-based material grows, the distance between electrodes decreases, but the surface area increases, so the current increases and power consumption increases, making it generally inefficient. The electrode plate 62 is preferably rectangular or square in shape when viewed from the front of its main surface, or polygonal in shape. Furthermore, the electrode plate 62 is not limited to the flat plate shape shown in the figure, but can be a plate shape having a bent portion and / or curved portion in at least a part thereof, or it may have a thickness that changes in at least a part thereof. Note that "plate shape" means a shape in which the dimensions of the main surface (length and width, etc.) are long relative to the thickness, and this includes rectangular parallelepiped shapes and disc shapes. In addition, in order to avoid current concentration, electrode plates 62 with corners at the periphery or four corners, such as rectangular parallelepipeds, may be processed by chamfering to eliminate the corners, or by processing to change the thickness at the periphery and in the center, and these are also included in the plate shape.

[0032] Then, when electrode plates 62 that provide either the polarity of the anode 61a or the cathode 61b are arranged alternately as shown in the figure, the refined titanium-based material 63 is deposited on each surface (electrodeposition surface) of the cathode 61b that faces the anode 61a (see Figure 2). For this reason, such an alternating arrangement of electrode plates 62 is suitable for mass production because a relatively large amount of refined titanium-based material 63 can be obtained in a single electrolytic refining process. For example, 10 to 100 electrode plates 62, or even more in some cases, may be arranged in a row.

[0033] As described later, after a predetermined electrolytic refining is completed, the polarity of the anode 61a and cathode 61b of each electrode plate 62 may be reversed when performing the next electrolytic refining. When the polarity is reversed, multiple electrode plates 62 that are anodes 61a in Figure 1 all become cathodes 61b, and multiple electrode plates 62 that are positioned between them and are cathodes 61b all become anodes 61a. Each of the multiple electrode plates 62, which are arranged alternately across the molten salt bath Bm, is assigned either the polarity of anode 61a or cathode 61b each time electrolytic refining is performed. Furthermore, when performing multiple electrolytic processes as described later, when the first electrolytic process, in which the crude titanium-based material obtained in the extraction process is used as the anode 61a, is completed, residue of the crude titanium-based material remains on the anode 61a. Therefore, it is preferable that the second electrolytic process be performed after replacing the anode 61a containing the residue with another electrode plate 62 and then reversing the polarity.

[0034] The electrode replacement device 1 used for replacing the electrode 61 as described above comprises an electrode storage container 2 having an opening 2a on the lower side that can be airtightly connected to the opening 51c of the electrolytic cell 51 and which stores an electrode plate 62 inside; an electrode holding mechanism 3 that holds the electrode plate 62 and can move the electrode plate 62 between the electrode storage container 2 and the electrolytic cell 51 while connected at the openings 51c and 2a between them; and a container opening / closing mechanism 4 that opens and airtightly closes the opening 2a of the electrode storage container 2. The main parts of the electrode replacement device 1 are preferably made of steel such as stainless steel.

[0035] When using this electrode replacement device 1, first, the opening 2a of the electrode storage container 2 is airtightly connected to the opening 51c of the electrolytic cell 51, the opening 2a of the electrode storage container 2 is opened with the container opening / closing mechanism 4, and the opening 51c of the electrolytic cell 51 is opened with the cell opening / closing mechanism 52. In this state, the electrode plate 62 held by the electrode holding mechanism 3 is moved from inside the electrode storage container 2 to inside the electrolytic cell 51, and as shown in Figure 1, the electrode plate 62 is immersed in the molten salt bath Bm.

[0036] Next, electrolytic refining is performed using molten salt electrolysis. In electrolytic refining, the crude titanium-based material contained in each anode 61a dissolves in the molten salt bath Bm, and the refined titanium-based material 63 is deposited on each cathode 61b.

[0037] When electrolytic refining is complete, the electrode holding mechanism 3 lifts the electrode plate 62 inside the electrolytic cell 51 from the molten salt bath Bm and moves it into the electrode storage container 2. At this time, any molten salt adhering to the surrounding area or that has entered the gaps inside the electrode plate 62 can be removed by flowing out from the electrode holding mechanism 3. Next, as shown in Figure 2, the container opening / closing mechanism 4 seals the opening 2a of the electrode storage container 2 airtight. At this time, to prevent the molten salt bath Bm inside the electrolytic cell 51 from coming into contact with the atmosphere, the tank opening / closing mechanism 52 also seals the opening 51c of the electrolytic cell 51 airtight. If the molten salt bath Bm contains magnesium chloride, the incorporation of moisture from the atmosphere into the molten salt bath Bm is suppressed by the closure of the opening 51c of the electrolytic cell 51 by the tank opening / closing mechanism 52.

[0038] Next, although not shown in the diagram, the connection between the opening 2a of the electrode storage container 2 and the opening 51c of the electrolytic cell 51 is released, and the electrode storage container 2, together with the electrode holding mechanism 3, is moved to another location from above the electrolytic cell 51.

[0039] Subsequently, the temperature of the refined titanium-based material 63 on the electrode plate 62 inside the electrode container 2 can be reduced to a level where oxidation is unlikely, for example, by supplying a low-temperature inert gas to the inside of the electrode container 2 through the vent 7 described later, or by operating a cooling jacket such as a water-cooled type (not shown). After this temperature has decreased to a level where oxidation is unlikely, the electrode plate 62 can be removed from inside the electrode container 2. Furthermore, the electrode plate 62 can be washed with water or the like to remove any molten salt adhering to it. Once the electrode plate 62 has cooled from the high temperature caused by immersion in the molten salt bath Bm to about 200°C, it will not oxidize significantly even when in contact with the atmosphere. Alternatively, the electrode storage container 2, which has been moved to another location, may be connected to a vacuum separation device (not shown) to create a high-temperature, vacuum atmosphere inside the electrode storage container 2, and the molten salt adhering to the electrode plate 62 may be separated by distillation. In this case, the electrode plate 62 can be removed from inside the electrode storage container 2 after the temperature has decreased, and the above-mentioned cleaning procedure is not required.

[0040] When performing the next electrolytic refining, a new electrode plate 62 is placed inside the same electrode storage container 2 as described above, held in place by the electrode holding mechanism 3, or another electrode storage container 2 is prepared with a new electrode plate 62 already placed inside. Having another electrode storage container 2 prepared allows for faster replacement of the electrode plate 62, improving productivity. Then, the opening 2a of the electrode storage container 2 is airtightly connected to the opening 51c of the electrolytic cell 51, and after opening the respective openings 2a and 51c with the container opening / closing mechanism 4 and the cell opening / closing mechanism 52, the electrode plate 62 is immersed in the molten salt bath Bm as shown in Figure 1. The subsequent steps are the same as described above, and further explanation is omitted.

[0041] By using the electrode exchange device 1 in this manner, each electrode plate 62, which is arranged alternately as the anode 61a or cathode 61b, can be exchanged while suppressing contact with the atmosphere. In particular, as the molten salt electrolysis of the electrolytic refining continues, the Ti contained in the crude titanium-based material in the anode 61a is consumed and the O content relatively increases, making it difficult to use continuously for a long period of time. By using the electrode exchange device 1, it becomes easy to provide new crude titanium-based material for electrolytic refining. As a result, it becomes possible to industrially mass-produce titanium-based electrodeposits as the refined titanium-based material 63 deposited on the cathode 61b. In addition, the electrode exchange device 1 can remove the electrode plate 62 of the cathode 61b from inside the electrolytic cell 51 before the refined titanium-based material 63 on the cathode 61b comes into contact with the anode 61a and a short circuit occurs.

[0042] As an example, in the illustrated electrode replacement device 1, the electrode storage container 2 is configured to include, for example, a cylindrical peripheral wall portion 2b, such as an ellipse or rectangular tube, having a corresponding cross-sectional shape that is substantially the same as the peripheral wall portion 51a of the electrolytic cell 51 in a cross-section perpendicular to the depth direction of the molten salt bath Bm, a top portion 2c that seals the upper side of the peripheral wall portion 2b, and an opening 2a on the lower side of the peripheral wall portion 2b. The container opening / closing mechanism 4 is, for example, a gate valve, and is provided on the lower side of the peripheral wall portion 2b of the electrode storage container 2, and is operated to open or close the opening 2a.

[0043] In this example, the electrode holding mechanism 3 includes a holding rod 3a made of stainless steel or heat-resistant steel, which is provided for each electrode plate 62 and extends vertically to suspend and hold each electrode plate 62, and a lifting plate 3b located outside the electrode storage container 2 above the holding rod 3a, to which each holding rod 3a is attached at its upper end. The holding rods 3a are connected to the electrode plates 62 at their lower ends. In order to ensure stable holding of the electrode plates 62, two holding rods 3a may be attached to each electrode plate 62, for example, as shown in Figure 3, with one rod on each side of the upper surface of the electrode plate 62 at an outer position in the width direction (vertical direction in Figure 3). One or more holding rods 3a may be provided for each electrode plate 62. In addition, each holding rod 3a extends through the top 2c of the electrode storage container 2. In the embodiments shown in Figures 1 to 3, when the electrode plate 62 is moved by the electrode holding mechanism 3, the holding rod 3a slides and is displaced relative to the top portion 2c. Therefore, it is preferable to provide a sealing member such as an O-ring for the sliding part at the location on the top portion 2c through which the holding rod 3a passes. The lifting plate 3b is provided on the upper side of the top portion 2c of the electrode storage container 2 and is driven to move up and down in the vertical direction by a drive source (not shown).

[0044] The electrode replacement device 1 may be provided with an electrical connection mechanism 5 that electrically connects the power supply and the electrode plate 62. Specifically, the electrical connection mechanism 5 may consist of plate-shaped or other shaped conductors 5a, 5b (so-called busbars, etc.) made of copper, aluminum, etc., located outside the electrode storage container 2, for example above the lifting plate 3b, and connected to the power supply, and wires 5c, 5d made of copper, nickel, carbon steel, iron, etc., extending vertically in parallel with the aforementioned holding rod 3a, and connecting the electrode plate 62 to the conductors 5a, 5b. Two types of conductors 5a, 5b and wires 5c, 5d are provided, one connected to the positive terminal of the power supply and the other connected to the negative terminal. Of the electrode plates 62 arranged in a direction perpendicular to the depth direction of the molten salt bath Bm, every other electrode plate 62 that is given the polarity of either the anode 61a or the cathode 61b (anode 61a in Figures 1-3) is connected to a conductor 5a and a wire 5c, and every other electrode plate 62 that is given the polarity of the other (cathode 61b in Figures 1-3) is connected to a conductor 5b and a wire 5d.

[0045] The conductors 5c and 5d are connected to the upper surface of the electrode plate 62 at a position between the two retaining rods 3a in the width direction, as shown in Figure 3, for example, and there may be two conductors per electrode plate 62. One or more conductors 5c and 5d may be connected to one electrode plate 62. As shown in Figures 1 and 2, the conductors 5c and 5d extend vertically inside the electrode housing container 2, on the back or rear side of the paper beyond the retaining rods 3a at the front of the paper in the figures, and pass through the top 2c of the electrode housing container 2 to connect to conductor 5a or 5b.

[0046] When replacing the electrode plate with the electrode replacement device 1, the electrode plate 62 can be replaced together with the conductors 5a and 5b and the wires 5c and 5d.

[0047] In order to prevent the holding rod 3a and the conductors 5c and 5d from becoming extremely hot due to the heat of the molten salt bath Bm, it is preferable to position the electrode plate 62 in the molten salt bath Bm such that its upper portion is exposed above the surface of the molten salt bath Bm. In Figures 1 to 10, the retaining rod 3a and the conductors 5c and 5d are shown offset from the widthwise centerline on the upper surface of the electrode plate 62, but they may also be placed on the widthwise centerline. From the viewpoint of ensuring uniformity of the load received and the current and voltage, it is preferable to place the retaining rod 3a and the conductors 5c and 5d at symmetrical positions on the widthwise centerline of the electrode plate 62.

[0048] In addition, the electrode replacement device 1 may be provided with one or more shielding plates 6, preferably two or three, to shield the inside of the electrode storage container 2 from the molten salt bath Bm inside the electrolytic cell 51. By providing the shielding plates 6, it is possible to suppress the transfer of heat from the molten salt bath Bm to the conductors 5c and 5d above it, and to the sealing member between the top 2c and the holding rod 3a, and to block the rise of evaporated material from the molten salt bath Bm. The shielding plates 6 cover the upper side of the electrode plate 62 held by the electrode holding mechanism 3 and are arranged almost parallel to the surface of the molten salt bath Bm, and can be attached, for example, in the middle of the holding rod 3a. In this case, as shown in Figures 1 and 2, the shielding plates 6 move vertically along with the movement of the electrode plate 62 by the holding rod 3a of the electrode holding mechanism 3. The shielding plates 6 may be provided in an insulated state from the conductors 5c and 5d.

[0049] Furthermore, it is preferable to provide a vent 7 in the electrode storage container 2, for example, in the peripheral wall 2b. By connecting a source of inert gas, such as argon gas, which can be placed outside the electrode storage container 2, to the vent 7, the inert gas can be supplied to the inside of the electrode storage container 2 through the vent 7. When inert gas is supplied to the inside of the electrode storage container 2 from the vent 7, and the pressure inside the electrode storage container 2 is slightly higher than that inside, the intrusion of outside air into the inside of the electrode storage container 2 is suppressed. In this case, as shown in Figure 1, it is also possible to suppress the entry of evaporated material from the molten salt bath Bm into the inside of the electrode storage container 2. In addition, if an inert gas with a relatively low temperature is supplied from the vent 7 during electrolytic refining, the temperature rise inside the electrode storage container 2, which is in close proximity to the molten salt bath Bm and exposed to high temperatures, can be suppressed, and the melting or deterioration of the aforementioned conductors 5c, 5d and sealing members due to this heat can be prevented.

[0050] Incidentally, the electrode storage container 2 of the electrode replacement device 1 shown in Figures 1 and 2 has a storage space 2d with a constant volume, and its volume does not change when the electrode plate 62 is moved by the electrode holding mechanism 3.

[0051] On the other hand, in the electrode replacement device 1 shown in Figures 4 and 5, a bellows-shaped wall portion 12e that expands and contracts vertically is provided on a part of the peripheral wall portion 12b of the electrode storage container 12. Here, the holding rod 3a of the electrode holding mechanism 3 is fixedly attached to the top portion 12c of the electrode storage container 12. When the electrode plate 62 is moved between the inside of the electrode storage container 12 and the inside of the electrolytic cell 51 by the electrode holding mechanism 3, the storage space 12d of the electrode storage container 12 deforms as the bellows wall portion 12e expands and contracts in accordance with the movement of the electrode plate 62 by the electrode holding mechanism 3, as shown in Figures 4 and 5, resulting in a change or increase or decrease in volume.

[0052] As shown in Figures 4 and 5, the retaining rod 3a and lifting plate 3b of the electrode retaining mechanism 3 move together with the top 12c of the electrode storage container 12 without sliding against it. In the electrode replacement device 1 shown in Figures 1 and 2, in order to suppress thermal degradation of the aforementioned sealing member provided on the top 2c, the hot lower part of the retaining rod 3a is allowed to cool sufficiently before sliding that part of the retaining rod 3a inside the sealing member. In contrast, in the electrode replacement device 1 shown in Figures 4 and 5, the retaining rod 3a does not slide against the top 12c, so such a waiting time for the retaining rod 3a to cool is unnecessary. As a result, in the electrode replacement device 1 shown in Figures 4 and 5, the movement of the electrode plate 62 by the electrode retaining mechanism 3 can be performed in a shorter time compared to those shown in Figures 1 and 2, and there is a high possibility that the productivity of titanium-based electrodeposits can be improved. The electrode replacement device 1 shown in Figures 4 and 5 has a configuration that is almost the same as that shown in Figures 1 and 2, except for the electrode storage container 12.

[0053] The electrode exchange device 1 described above has electrode storage containers 2 and 12 that have storage spaces 2d and 12d that store together all of the electrode plates 62 that give either the polarity of the anode 61a or the cathode 61b, and the electrode plates 62 that give the polarity of the other. In contrast, the electrode exchange device 21 shown in the plan view of Figure 6 has an electrode storage container 22 that includes a plurality of divided storage containers 22a and 22b, each containing a divided storage container 22a that stores an electrode plate 62 that gives either the polarity of the anode 61a or the cathode 61b, as shown by dashed lines of different lengths in the figure, and a separate divided storage container 22b that stores an electrode plate 62 that gives the polarity of the other.

[0054] Each divided containment container 22a, 22b has a comb-like shape in plan view, in order to house every other electrode plate 62 that gives either the polarity of the anode 61a or the cathode 61b, and every other electrode plate 62 that gives the polarity of the other, from among the electrode plates 62 arranged in a direction perpendicular to the depth direction of the molten salt bath Bm (left-right direction in Figure 6). These divided containment containers 22a, 22b are arranged above the electrolytic cell 51 in a position where the teeth of the comb-like structure interlock with each other, as shown in Figure 6.

[0055] Near the lower openings of each divided containment vessel 22a and 22b, comb-shaped container opening and closing mechanisms 24a and 24b corresponding to each divided containment vessel 22a and 22b are respectively positioned. In Figure 6, the container opening and closing mechanisms 24a and 24b, both in the position to open the openings, open and airtightly close the lower openings of the divided containment vessels 22a and 22b.

[0056] Although not shown in Figure 6, two cell opening / closing mechanisms, each with a comb-like planar shape, are positioned directly below the container opening / closing mechanisms 24a and 24b of the electrolytic cell 51, respectively. The two cell opening / closing mechanisms are designed so that when they interlock, the opening of the electrolytic cell 51 is covered without gaps and airtightly closed. However, the cell opening / closing mechanisms are not limited to the two comb-like shapes described above; for example, a single rectangular cell opening / closing mechanism that covers the entire opening of the electrolytic cell 51 may also be used. The raising and lowering operation of the electrode plate 62 by the electrode holding mechanism may be easier with two comb-like cell opening / closing mechanisms than with a single rectangular cell opening / closing mechanism.

[0057] After the electrolytic refining is complete, for example, when replacing every other electrode plate 62 using one of the divided storage containers 22a, the electrode plate 62 is moved from inside the electrolytic cell 51 to inside one of the divided storage containers 22a by an electrode holding mechanism (not shown here). Then, as shown in Figure 7, the opening of one of the divided storage containers 22a is hermetically closed by the container opening / closing mechanism 24a corresponding to one of the divided storage containers 22a. At this time, although not shown, the cell opening / closing mechanism of the electrolytic cell 51 is also operated to hermetically close the opening of the electrolytic cell 51.

[0058] Subsequently, the connection between the opening of one of the divided storage containers 22a and the opening of the electrolytic cell 51 is released, and one of the divided storage containers 22a is moved to another location from above the electrolytic cell 51. At this point, the electrode plate 62 that was stored inside one of the divided storage containers 22a is removed. When performing the next electrolytic refining, the divided storage container 22a with the new electrode plate 62 inside is placed above the electrolytic cell 51, their openings are connected, and then the openings are opened using the container opening / closing mechanism 24a and the cell opening / closing mechanism, and the new electrode plate 62 is moved into the electrolytic cell 51 using the electrode holding mechanism.

[0059] When using the other divided containment container 22b, the replacement of every other electrode plate 62 in the other divided containment container 22a can be performed in much the same manner as described above.

[0060] (Molten salt electrolysis apparatus) The molten salt electrolysis apparatus comprises the electrode exchange devices 1 and 21, the electrolytic cell 51, and the electrode 61 as described above. The electrolytic cell 51 is also provided with a cell opening / closing mechanism 52 that opens and closes the opening 51c of the electrolytic cell 51 in an airtight manner, as also described above.

[0061] Furthermore, a temperature control mechanism 53, such as a heat exchanger, may be provided inside the electrolytic cell 51, located below the bottom 51b of the electrodes 61 when the electrodes 61 are placed inside, to heat or cool the molten salt bath Bm. If necessary, the temperature of the molten salt bath Bm can be adjusted, for example, by the flow of a gaseous or liquid heat transfer medium in the piping of the temperature control mechanism 53, or by infrared heating through the transparent piping of the temperature control mechanism 53. A heater (not shown) may also be provided outside the electrolytic cell 51.

[0062] (Method for manufacturing titanium-based electrodeposits) To produce titanium-based electrodeposits, crude titanium-based material is prepared in advance prior to the electrolytic process, which involves electrolytic refining using the molten salt electrolytic apparatus described above. The crude titanium-based material can be obtained by an extraction process.

[0063] In the extraction process, a mixture containing titanium raw materials such as titanium ore containing titanium oxides such as titanium dioxide (TiO2), a reducing agent containing aluminum (Al), and a separating agent is heated. The reaction at this time is complex, but generally, it is thought that a reaction such as 3TiO2 + 4Al → 3Ti + 2Al2O3 occurs. Here, a considerable amount of Al and O are dissolved in Ti, which corresponds to the crude titanium-based material. The heating temperature may be 1500°C to 1800°C. After the mixture becomes molten upon heating, the crude titanium-based material (liquid or solid) and slag separate due to the density difference, so the crude titanium-based material (Ti in the above reaction equation) can be extracted.

[0064] The titanium raw material used in the extraction process can be any material containing titanium oxide, for example, titanium ore that has undergone upgrading treatment such as leaching or other treatments as needed. The TiO2 content in the titanium ore used as the titanium raw material may be, for example, 50% by mass or more, typically 80% by mass or more, and particularly 90% by mass or more. The separating agent is used to generate slag after heating. Specifically, the separating agent is preferably one or more selected from calcium fluoride, aluminum fluoride, potassium fluoride, magnesium fluoride, calcium chloride, calcium oxide, and sodium fluoride. Among these, calcium fluoride (CaF2) is particularly preferred because it provides excellent separation of crude titanium-based materials from the mixture and has little effect on anything other than the separation. The reducing agent may consist substantially of aluminum (Al) alone, or it may also contain Ca, Na, etc. For example, the mixture may be prepared by adjusting the molar ratio of TiO2:Al:CaF2 to 3:4 to 7:2 to 6.

[0065] The crude titanium-based material obtained in the extraction process contains Ti, Al, and O, and may have, for example, a Ti content of 50% to 80% by mass, an Al content of 5% to 30% by mass, and an O content of 8% to 30% by mass. Typically, the Ti content of the crude titanium-based material may be 60% or more by mass, the Al content 20% or less by mass, and the O content 20% or less by mass. However, in the crude titanium-based material, the Al and O content in Ti may be less than the above-mentioned amounts and may be present in amounts that can be considered unavoidable impurities.

[0066] Such crude titanium-based materials are electrically conductive and can be incorporated into the anode 61a in the electrolytic process described below for electrolytic refining. The resistivity of the crude titanium-based material measured at room temperature is, for example, 1 × 10⁻⁶. -8 Ω·m ~ 1 × 10 -4 Ω·m, typically 1 × 10⁻⁶ -7 Ω·m~5×10 -5 It is Ω·m.

[0067] In the electrolysis process, the crude titanium-based material of the anode 61a is dissolved in the molten salt bath Bm using the molten salt electrolytic apparatus described above, and the refined titanium-based material 63 is deposited on the cathode 61b in an electrolytic refining process.

[0068] Here, the molten salt bath Bm may be a chloride bath mainly containing metal chlorides, for example, alkali metal chlorides and / or alkaline earth metal chlorides, for example, 70 mol% or more, more preferably 80 mol% or more, or more preferably 90 mol% or more. Such a chloride bath is preferred over fluoride baths, bromide baths, and iodide baths because it is less corrosive, has a lower environmental impact, and is less expensive. In particular, when a chloride bath containing magnesium chloride (MgCl2) is used, a purified titanium-based material 63 can be obtained in which not only the O content but also the Al content is sufficiently reduced. The MgCl2 content in the chloride bath is preferably 30 mol% or more, more preferably 50 mol% or more, more preferably 80 mol% or more, more preferably 85 mol% or more, and especially preferably 90 mol% or more. The chloride bath may contain one or more metal chlorides selected from lithium chloride (LiCl), sodium chloride (NaCl), potassium chloride (KCl), rubidium chloride (RbCl), cesium chloride (CsCl), beryllium chloride (BeCl2), calcium chloride (CaCl2), strontium chloride (SrCl2), and barium chloride (BaCl2) in amounts of, for example, 70 mol% or less, further 50 mol% or less, further 20 mol% or less, further 10 mol% or less, and further 5 mol% or less.

[0069] Furthermore, the molten salt bath Bm may, if necessary, contain lower titanium chlorides with a lower valence of Ti than titanium tetrachloride, specifically titanium dichloride (TiCl2) or titanium trichloride (TiCl3). The titanium ion content in the molten salt bath Bm is preferably 3 mol% or more, more preferably 5 mol% or more, even more preferably 6 mol% or more, and may even be 10 mol% or more, but is preferably 20 mol% or less. The content of metal chlorides and metal ions in the molten salt bath Bm can be measured by ICP emission spectrometry or atomic absorption spectrometry. The titanium ion content is determined as a percentage of the total metal ion content in the molten salt bath Bm.

[0070] As the anode 61a, for example, one containing the crude titanium-based material obtained in the extraction process described above is used. As an example, the anode 61a has a plate-like outer shape and has a cage-like container with numerous through holes made of Ni, Ni-based alloy, Hastelloy, or Ni-coated steel, in which case the crude titanium-based material in granular or powder form can be placed inside the cage-like container. When the anode 61a has a cage-like container, the wires 5c and 5d can be connected to the cage-like container. However, the form of the anode 61a is not limited to this, and for example, it may be a plate-like object made from crude titanium-based material by melting and casting. The cathode 61b can be a plate-like object with at least its surface made of Ti, for example, a titanium plate made entirely of Ti. As will be described in detail later, when performing multiple electrolysis processes, the cathode 61b, such as a titanium plate on which the refined titanium-based material 63 has been deposited in the first electrolysis process, may be used as the anode 61a in the second electrolysis process. In this case, the appearance of the cathode 61b, such as a titanium plate containing the refined titanium-based material 63, only needs to be plate-like. While it is possible to place a dual electrode between the anode 61a and the cathode 61b, a dual electrode is not required.

[0071] For example, as shown in FIG. 1, except for the anodes 61a located at both ends in the direction orthogonal to the depth direction of the molten salt bath Bm, two rectangular anodes 61a in this cross-section are stacked and arranged. This is intended to provide one rectangular cage-shaped container for each electrodeposition surface of the cathodes 61b located on both sides sandwiching the anode 61a. However, it is not always necessary to provide two cage-shaped containers in a stacked manner, and one anode 61a of the cage-shaped container may be arranged between the cathodes 61b.

[0072] In the electrolysis process, electricity is supplied from a power source to the anode 61a and the cathode 61b of the electrode 61, and a voltage is applied between the electrodes 61. As a result, titanium ions elute from the crude titanium-based material contained in the anode 61a into the molten salt bath Bm, and the titanium ions are deposited as titanium atoms on the cathode 61b to become the purified titanium-based material 63. The purified titanium-based material 63 deposited on the cathode 61b may correspond to a titanium-based electrodeposit.

[0073] As conditions for the electrolysis process, for example, the temperature of the molten salt bath Bm is 450°C to 900°C, and the current density at the cathode 61b is 0.01 A / cm 2 ~3 A / cm 2 It may be set as such. The current density can be calculated by the formula: Current density (A / cm 2 ) = Current (A) ÷ Electrodeposition area (cm 2 ). In addition to being able to continuously flow a current through the electrode 61, a power-off period for setting the current value to zero may be provided, and a pulsed current in which the power-on period and the power-off period are alternately repeated may be flowed. The maximum voltage between the electrodes 61 may be, for example, 0.2 V to 3.5 V. During the electrolysis process, it is preferable to maintain the inside of the electrolytic cell 51 in an inert atmosphere such as argon.

[0074] When electrolytic refining is performed as described above in the electrolytic process, the amount of refined titanium-based material 63 deposited per unit time on the cathode 61b decreases due to factors such as a gradual decrease in the Ti content of the crude titanium-based material in the anode 61a. In addition, the electrical resistance of the anode 61a increases. Furthermore, as a result, the refined titanium-based material 63 may not deposit on the cathode 61b in the desired form. Thus, it becomes difficult to continue using the anode 61a. In such cases, it is desirable to replace the electrode plate 62 that was used as the anode 61a and / or cathode 61b using the electrode replacement devices 1 and 21 described above.

[0075] When the electrode plate 62 of the cathode 61b is removed from the electrolytic cell 51 using the electrode replacement devices 1 and 21, the refined titanium-based material 63 electrodeposited on the electrode plate 62 can be recovered by physically peeling it off the electrode plate 62 using a cutting tool or the like.

[0076] The electrolysis process can be carried out in multiple stages to further purify the refined titanium-based material 63 obtained therefrom. When multiple stages of electrolysis are performed, the refined titanium-based material 63 deposited on the cathode 61b in the preceding electrolysis stage is used as the crude titanium-based material in the subsequent electrolysis stage. That is, in the subsequent electrolysis stage, the refined titanium-based material 63 deposited on the cathode 61b in the preceding electrolysis stage is used as the crude titanium-based material, and the anode 61a containing this crude titanium-based material is used. As a result, in the subsequent electrolysis stage, refined titanium-based material 63, from which impurities have been further removed from the crude titanium-based material, is deposited on the cathode 61b. By performing multiple stages of electrolysis, it is also possible to produce electrodeposited metallic titanium that contains almost no impurities.

[0077] Multiple electrolysis processes can be carried out continuously using the same electrolytic cell 51 and molten salt bath Bm. In this case, the polarity of the anode 61a and cathode 61b in the preceding electrolysis process is reversed, and the cathode 61b on which the refined titanium-based material 63 has precipitated can be used as the anode 61a in the subsequent electrolysis process. In this case, a new cathode 61b is placed where the anode 61a was placed in the preceding electrolysis process.

[0078] When performing multiple electrolysis steps using the electrode exchange device 21 described above, first, the first electrolysis step is performed in the state shown in Figure 6 to obtain refined titanium-based material 63 on the electrode plate 62 of the cathode 61b. Next, the opening of the divided storage container 22a and the opening of the electrolytic cell 51 are closed using the container opening / closing mechanism 24a and the cell opening / closing mechanism, respectively, and the electrode plate 62 that was the anode 61a is stored inside the divided storage container 22a using the electrode holding mechanism, as shown in Figure 7. The electrode plate 62 is moved to another location together with the divided storage container 22a and removed from the divided storage container 22a.

[0079] Subsequently, in order to perform the second electrolysis stage, a new electrode plate 62, which will be used as the cathode 61b in the second stage, is placed inside the electrolytic cell 51 from inside the divided containment container 22a, as shown in Figure 8. In Figure 8, the new electrode plate 62 is shown as two plate-shaped plates stacked on top of each other, but it can also be a single titanium plate or the like without a cage-like container. The thickness of the single new electrode plate 62 is not particularly limited, but it can be approximately the same size as the electrode plate 62 used as the cathode 61b in the first stage. The inter-electrode distance in the second electrolysis stage may change slightly to be longer or shorter than the inter-electrode distance in the first electrolysis stage. Note that in Figures 8 to 10, for ease of viewing, the divided containment containers 22a and 22b shown by dashed lines in Figures 6 and 7 are omitted from the illustration.

[0080] In the second electrolysis step, as shown in Figure 8, the polarity of the anode 61a and cathode 61b is reversed and a voltage is applied between each electrode plate 62. As a result, the refined titanium-based material 63 that was deposited on the electrode plate 62 that was cathode 61b in the first step and anode 61a in the second step dissolves into the molten salt bath Bm as crude titanium-based material, and as shown in Figure 9, an even higher purity refined titanium-based material 63 is deposited on the electrode plate 62 that is cathode 61b in the second step.

[0081] After the second electrolysis process is completed, the openings of the divided storage container 22a and the electrolytic cell 51 are closed by the container opening / closing mechanism 24a and the cell opening / closing mechanism, respectively, and the electrode plate 62, which was used as the cathode 61b in the second stage, can be stored and recovered inside the divided storage container 22a by the electrode holding mechanism, as shown in Figure 10.

[0082] Alternatively, after the second electrolysis stage is completed, the electrode plate 62, such as a titanium plate, which was used as the cathode 61b in the second stage, may be reversed and the third electrolysis stage may be performed without recovering it. In this case, due to the reversal of polarity, the electrode plate 62, such as a titanium plate, which was used as the cathode 61b or anode 61a in the second stage, becomes the anode 61a or cathode 61b in the third stage, respectively, and the refined titanium-based material 63 on the anode 61a is used as the crude titanium-based material, and further refined titanium-based material 63 is deposited on the cathode 61b. After the third electrolysis stage, the refined titanium-based material 63 obtained on the electrode plate 62 that was used as the cathode 61b in the third stage can be recovered using the divided storage container 22b and the container opening / closing mechanism 24b, or the refined titanium-based material 63 may be reversed again and the fourth and subsequent electrolysis stages may be performed without recovering it.

[0083] As described above, by performing multiple electrolytic processes without removing the refined titanium-based material 63 from the molten salt bath Bm, it is possible to produce a high-purity titanium-based electrodeposit with an extremely low oxygen content.

[0084] (Titanium-based electrodeposits) The titanium electrodeposit, as the purified titanium-based material 63 obtained by one or more electrolytic processes, has a total content of impurities other than Ti of, for example, 40,000 ppm by mass or less, preferably 5,000 ppm by mass or less, more preferably 2,000 ppm by mass or less, even more preferably 1,000 ppm by mass or less, and particularly preferably 200 ppm by mass or less.

[0085] When titanium electrodeposits are made of metallic titanium, the product obtained in the first or second electrolytic stage may, for example, have an Al content of 5 to 20,000 ppm by mass, an O content of 50 to 20,000 ppm by mass, with the remainder consisting of Ti and unavoidable impurities. The product obtained in multiple electrolytic stages may have an Al content of 5 to 1,000 ppm by mass, an O content of 50 to 1,000 ppm by mass, with the remainder consisting of Ti and unavoidable impurities. It is also possible to produce titanium electrodeposits made of metallic titanium with purities of 4N5 or higher, and even 5N or higher.

[0086] Unavoidable impurities in titanium electrodepositories include those originating from the ore, chloride bath, reducing agent, separating agent, the containers constituting the electrolytic cell, and those generated when in contact with the atmosphere. Specifically, titanium electrodepositories may contain unavoidable impurities such as N (nitrogen) content of 0.03 mass% or less, C (carbon) content of 0.01 mass% or less, Fe content of 0.050 mass% or less, Mg content of 0.02 mass% or less, Ni content of 0.03 mass% or less, Cr content of 0.03 mass% or less, Si content of 0.001 mass% or less, Mn content of 0.05 mass% or less, and Sn content of 0.01 mass% or less. [Explanation of symbols]

[0087] 1, 21 Electrode exchange device 2, 12, 22 Electrode storage container 22a Divided containment vessel 22b Divided containment vessel 2a, 12a opening 2b, 12b peripheral wall part 2c, 12c top 2d, 12d storage space 12e Bellows wall section 3 Electrode holding mechanism 3a Retaining rod 3b Lifting plate 4, 24a, 24b Container opening / closing mechanism 5. Electrical connection mechanism 5a Conductor 5b Conductor 5c conductor 5d conductor wire 6 Shielding plate 7. Ventilation openings 51 Electrolytic cell 51a Peripheral wall part 51b bottom 51c opening 52 Tank opening / closing mechanism 53 Temperature control mechanism 61 Electrode 61a Anode 61b Cathode 62 Electrode plate 63. Refined Titanium-Based Materials Bm molten salt bath

Claims

1. An electrode replacement device used for replacing electrodes, including the anode and the cathode, in electrolytic refining, in which crude titanium-based material of the anode is dissolved in a molten salt bath inside an electrolytic cell and refined titanium-based material is deposited on the cathode. The crude titanium-based material contains Ti, Al, and O and is electrically conductive, and the electrode includes a portion in which electrode plates, each functioning as either the anode or the cathode, are arranged alternately. The electrode replacement device comprises an electrode storage container having an opening that can be airtightly connected to the opening of the electrolytic cell and storing the electrode plate inside; an electrode holding mechanism that holds the electrode plate and can move the electrode plate between the electrode storage container and the electrolytic cell while they are connected at the opening; and a container opening and closing mechanism that opens and airtightly closes the opening of the electrode storage container.

2. The electrode replacement device according to claim 1, wherein the electrode holding mechanism is provided for each electrode plate and comprises a holding rod that extends vertically to suspend and hold each electrode plate, and a lifting plate located above the holding rods and outside the electrode storage container, to which each of the holding rods is attached.

3. The electrode replacement device includes an electrical connection mechanism that electrically connects the power supply and the electrode plate. The electrode replacement device according to claim 2, wherein the electrical connection mechanism comprises a conductor located outside the electrode housing and connected to the power supply, and a conductor extending vertically parallel to the holding rod and connecting the electrode plate to the conductor.

4. The electrode replacement device according to claim 1, wherein the electrode replacement device is positioned to cover the upper side of the electrode plate held by the electrode holding mechanism, moves together with the movement of the electrode plate by the electrode holding mechanism, and includes a shielding plate that shields the inside of the electrode storage container from the molten salt bath inside the electrolytic cell.

5. The electrode replacement device according to claim 1, wherein the electrode storage container has a storage space of a certain volume.

6. The electrode replacement device according to claim 1, wherein the electrode storage container has a bellows wall portion that expands and contracts in accordance with the movement of the electrode plate between the inside of the electrode storage container and the inside of the electrolytic cell by the electrode holding mechanism, and a storage space that undergoes a change in volume as the bellows wall portion expands and contracts.

7. The electrode replacement device according to claim 1, wherein the electrode storage container has a storage space for storing both the electrode plate that provides the polarity of either the anode or the cathode and the electrode plate that provides the polarity of the other.

8. The electrode replacement device according to claim 1, wherein the electrode storage container has a plurality of divided storage containers that separately store the electrode plate that provides the polarity of either the anode or the cathode and the electrode plate that provides the polarity of the other.

9. The electrode replacement device according to claim 1, wherein the electrode storage container has a vent that allows an inert gas to be supplied inside it.

10. A molten salt electrolytic apparatus comprising an electrode replacement device according to any one of claims 1 to 9, the electrolytic cell, and the electrode, A molten salt electrolytic apparatus having an electrolytic cell having a cell opening / closing mechanism that opens and closes the opening of the electrolytic cell in an airtight manner.

11. The molten salt electrolytic apparatus according to claim 10, wherein the electrolytic cell is located below the electrodes when the electrodes are arranged inside, and has a temperature control mechanism for adjusting the temperature of the molten salt bath.

12. A method for producing titanium-based electrodeposits, A method for producing a titanium electrodeposited material, comprising an electrolytic step of performing electrolytic purification using the molten salt electrolytic apparatus described in claim 10, in which the crude titanium-based material of the anode is dissolved in a molten salt bath and the purified titanium-based material is deposited on the cathode.

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