Molten salt electrolysis apparatus and method for manufacturing titanium-based metal strips

Abstract

To provide a molten salt electrolytic apparatus and a method for manufacturing titanium strips that can continuously produce titanium-based metal materials. [Solution] The electrodeposition chamber 11 has a drum cathode 13 with a rotating shaft 14 and anodes 16a and 16b containing an anode raw material containing Ti, and a strip TS is formed on the outer circumferential surface 13a of the drum cathode; a winding chamber 21 is adjustable to an inert gas atmosphere and has a winding reel 22 for winding the strip TS; and a communication section 31 connects the electrodeposition chamber and the winding chamber and allows the strip TS sent from the electrodeposition chamber 11 to the winding chamber 21 to pass through. The electrodeposition chamber 11 has a pre-deposition space 11a and a main electrodeposition space 11b through which the outer circumferential surface region of the drum cathode 13 passes sequentially as the drum cathode rotates, and anodes are provided in the pre-deposition space 11a and the main electrodeposition space 11b, respectively, and molten salt is provided inside the communication section 31, and a temperature gradient can be set in which the temperature of the molten salt decreases from the electrodeposition chamber 11 side to the winding chamber 21 side.

Description

Technical Field

[0001] This invention relates to a molten salt electrolysis apparatus and a method for manufacturing a titanium-based metal strip.

Background Art

[0002] Smelting products obtained from smelting titanium ores, titanium-based scraps, etc. may be subjected to purification in order to further reduce the content of impurities such as oxygen. In this purification, these are placed as raw materials on the anode, a voltage is applied between the anode and the cathode in a molten salt bath, and molten salt electrolysis may be performed to deposit a high-purity titanium-based metal on the cathode.

[0003] Regarding this type of molten salt electrolysis, various conditions and modes have been studied so far. Conventionally, as techniques related to this, for example, those described in Patent Documents 1 to 5 exist.

[0004] Patent Document 1 describes "a method for manufacturing a titanium foil, including an electrodeposition step of performing electrolysis using an electrode including an anode and a cathode in a molten salt bath to deposit metallic titanium on the electrolysis surface of the cathode. In the electrodeposition step, as the anode, a titanium-based material containing titanium and having a conductivity with an aluminum content of 200 ppm by mass or more and 4500 ppm by mass or less and an oxygen content of 8000 ppm by mass or more and 15000 ppm by mass or less is used. As the cathode, a cathode containing 90% by mass or more of at least one selected from the group consisting of titanium, molybdenum, glassy carbon, and tungsten on the electrolysis surface is used. Titanium ions are previously included in the molten salt bath, and during the electrolysis, the temperature of the molten salt bath is maintained at 520°C or lower, and the current density at the cathode is ...... , ,

[0005] as follows, a method for manufacturing a titanium foil" is described.

[0005] Patent Document 2 describes a method for producing metallic titanium by electrolysis using electrodes including an anode and a cathode in a molten salt bath, wherein the anode is an anode containing metallic titanium, and the cathode is a cathode whose surface contains at least 90% by mass of molybdenum, the temperature of the molten salt bath is 515°C or lower, and the electrodes are energized with a pulsed current that periodically includes a period of 1.0 second or more of power interruption, and the average current density of the cathode over the entire period is 0.01 A / cm². 2 ~0.10A / cm 2 A method for producing metallic titanium, including a precipitation step, is described. Patent Document 2 states, "Figure 3 shows another electrolytic apparatus 11. In the electrolytic apparatus 11 of Figure 3, a cylindrical or columnar cathode 13b, which serves as a so-called cathode drum, is placed in a sealed electrolytic cell 12 such that a part of its cylindrical surface is immersed in a molten salt bath Bf. In this electrolytic apparatus 11, a plate-shaped anode 13a, which curves along the surface of the cylindrical cathode 13b, is placed in the molten salt bath Bf facing the surface of the cathode 13b." It also states, "In the electrolytic apparatus 11 of Figure 3, by rotating the cylindrical or columnar cathode 13b around its central axis and applying current to the electrodes 13 from a power source (not shown), sheet-like metallic titanium Ts is deposited on the surface of the cathode 13b. Then, by winding the metallic titanium Ts with a winding roll 15 further provided in the electrolytic apparatus 11, long lengths of metallic titanium Ts can be continuously produced while peeling them off the surface of the cathode 13b."

[0006] Patent Document 3 describes a molten salt electrolytic apparatus used for electrolytic refining to obtain a refined titanium-based material of higher purity than the crude titanium-based material from a crude titanium-based material containing Ti, Al, and O and having conductivity, by electrolysis using a molten salt bath, comprising: an electrolytic cell containing the molten salt bath, and an electrolytic cell having a plate-shaped anode containing the crude titanium-based material as an electrode, and a plate-shaped cathode positioned opposite the anode to deposit the refined titanium-based material; a current-carrying member provided from the outside to the inside through the opening of the electrolytic cell to electrically connect the anode and the cathode to a power source, respectively; and provided from the outside to the inside through the opening of the electrolytic cell The invention describes a molten salt electrolysis apparatus comprising electrode holding members for an anode and a cathode, which respectively hold the anode and the cathode on the inside, wherein the electrode holding members for the anode and / or cathode are movable in a direction that separates the anode and the cathode from each other in an opposing position; a lid that covers the opening of the electrolytic cell and has a hole formed therein that extends through the inside of the movable electrode holding member to allow the movement of the electrode holding member; and a sliding closing plate provided on the inside or outside of the electrolytic cell relative to the lid, which slides along with the movement of the electrode holding member while closing the hole.

[0007] Patent Document 4 describes a molten salt electrolytic apparatus comprising an electrolytic cell that performs electrolytic refining using electrodes including an anode and a cathode, wherein the electrolytic cell dissolves Ti from a crude titanium-based material of the anode and deposits a refined titanium-based material on the cathode in a molten salt bath, wherein the crude titanium-based material contains Ti, Al and O and is conductive, the electrodes include a portion in which electrode plates that function as either the anode or the cathode are arranged alternately, the electrolytic cell has two or more openable and closable communication ports that connect the inside and outside, and the two or more communication ports include at least a first communication port used for gas discharge and a second communication port located deeper in the depth direction of the electrolytic cell than the first communication port and used for molten salt discharge.

[0008] Patent Document 5 proposes "an agitator used for stirring a molten salt bath in which electrodes are immersed in an electrolytic cell, comprising: an impeller having a plurality of blades spaced apart in the direction of rotation and immersed in the molten salt bath; a rotating shaft that transmits rotational driving force to the impeller from a drive source outside the molten salt bath; a shaft sleeve surrounding the rotating shaft; an impeller case housing the impeller inside; a suction cylinder connected to the impeller case from the outside in the axial direction of the rotating shaft and guiding the molten salt of the molten salt bath into the impeller case; and a discharge cylinder connected to the impeller case on the outer circumference of the impeller and discharging the molten salt from inside the impeller case, wherein the suction cylinder has a suction opening that opens toward the space between the electrodes of the electrodes in the electrolytic cell." [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2024-33569 [Patent Document 2] Japanese Patent Publication No. 2021-31723 [Patent Document 3] Japanese Patent Publication No. 2024-50284 [Patent Document 4] Japanese Patent Publication No. 2024-94070 [Patent Document 5] Japanese Patent Publication No. 2023-20195 [Overview of the project] [Problems that the invention aims to solve]

[0010] Incidentally, molten salt electrolysis is usually performed in a batch method, where the current is stopped and the process terminated each time a certain amount of titanium-based metal is deposited on the cathode. In contrast, if continuous molten salt electrolysis were possible, mass production of titanium-based metal materials could be realized, and an improvement in manufacturing efficiency could be expected. However, when attempts were made to actually implement continuous molten salt electrolysis, various problems arose.

[0011] The object of this invention is to provide a molten salt electrolytic apparatus capable of continuously producing titanium-based metal materials, and a method for producing titanium-based metal strips using the same. [Means for solving the problem]

[0012] The molten salt electrolytic apparatus of this invention comprises an electrodeposition chamber having a rotatable drum cathode with a rotation axis positioned vertically to the bottom surface, and electrodes arranged around the drum cathode at a distance from the outer surface of the drum cathode and containing a Ti-containing anode material, wherein a titanium-based metal strip is formed on the outer surface of the drum cathode by applying a voltage between the electrodes in a molten salt bath, and a winding chamber having a winding reel that can be adjusted to an inert gas atmosphere inside and winds up the titanium-based metal strip sent from the electrodeposition chamber, and The electrodeposition chamber and the winding chamber are connected by a connecting section through which the titanium-based metal strip sent from the electrodeposition chamber to the winding chamber passes. The electrodeposition chamber has a pre-deposition space and a main electrodeposition space through which the outer peripheral surface region of the drum cathode passes sequentially as the drum cathode rotates. The anode is provided in the pre-deposition space and the main electrodeposition space, respectively. Molten salt is provided inside the connecting section, and a temperature gradient can be set such that the temperature of the molten salt decreases from the electrodeposition chamber side to the winding chamber side.

[0013] Preferably, the outer surface of the drum cathode contains at least one selected from the group consisting of Ti, Zr, Mo, and Nb.

[0014] Preferably, the drum cathode has a conductive member made of copper or a copper-based alloy on the axial side of the outer circumferential surface.

[0015] The drum cathode preferably has a cooling section inside.

[0016] The cooling unit is preferably a heat exchanger through which a cooling medium can flow.

[0017] Preferably, the winding chamber has a cutting portion capable of cutting the titanium-based metal strip before reaching the winding reel in the feeding path of the titanium-based metal strip.

[0018] The method for manufacturing a titanium-based metal strip of this invention is a method for manufacturing a titanium-based metal strip using any of the above-mentioned molten salt electrolysis apparatuses. In a state where the drum cathode and the winding reel are rotated respectively, in the electrolysis chamber, by applying a voltage between the electrodes in a molten salt bath, a titanium-based metal is deposited in a strip shape on the outer peripheral surface of the drum cathode to form a titanium-based metal strip. The titanium-based metal strip is peeled off from the outer peripheral surface of the drum cathode at a location where it has passed between the anode in the main electrolysis space, and is sent from the communication part to the winding chamber. And it includes winding the titanium-based metal strip around the winding reel in the winding chamber.

[0019] In the above manufacturing method, it is preferable to make the temperature of the molten salt bath in the electrolysis chamber higher in the main electrolysis space than in the pre-electrolysis space.

[0020] In the above manufacturing method, it is preferable to set the temperature of the molten salt bath in the pre-electrolysis space to be 480 °C or higher and lower than 550 °C, and the temperature of the molten salt bath in the main electrolysis space to be 550 °C or higher and 770 °C or lower.

[0021] In the above manufacturing method, it is preferable to alternately pass an electric current through the anode and the drum cathode in the pre-electrolysis space, and the anode and the drum cathode in the main electrolysis space.

[0022] In the above manufacturing method, it is preferable to set the inter-electrode distance between the drum cathode and the anode in the pre-electrolysis space within a range of 0.2 mm or more and 3.0 mm or less, and the inter-electrode distance between the drum cathode and the anode in the main electrolysis space within a range of 0.3 mm or more and 10.0 mm or less.

[0023] In the above manufacturing method, it is preferable that the molten salt bath contains divalent titanium ions and / or trivalent titanium ions, and the titanium ion concentration is higher in the pre-electrolysis space than in the main electrolysis space.

[0024] In the above manufacturing method, it is preferable that on the outer peripheral surface of the drum cathode, the deposition thickness of the titanium-based metal in the main electrolysis space is thicker than the deposition thickness of the titanium-based metal in the pre-electrolysis space.

Advantages of the Invention

[0025] According to the molten salt electrolysis apparatus of this invention, a titanium-based metal material can be continuously manufactured.

Brief Description of the Drawings

[0026] [Figure 1] It is a horizontal cross-sectional view schematically showing a molten salt electrolysis apparatus according to an embodiment of this invention and a titanium-based metal strip formed therein, and is a horizontal cross-sectional view along line I-I of FIG. 2. The illustration of the tension roller shown in FIG. 5 and the like is omitted. [Figure 2] It is a vertical cross-sectional view along line II-II of FIG. 1. [Figure 3] It is a vertical cross-sectional view showing the structure near the lower end of the drum cathode disposed in the electrolysis chamber of the molten salt electrolysis apparatus of FIG. 2 and the take-up reel in the take-up chamber. [Figure 4] It is a horizontal cross-sectional view schematically showing a molten salt electrolysis apparatus according to another embodiment and a titanium-based metal strip formed therein. The illustration of the tension roller shown in FIG. 5 and the like is omitted. [Figure 5] It is a horizontal cross-sectional view similar to FIG. 1, schematically showing an example of the state when starting molten salt electrolysis in the molten salt electrolysis apparatus of FIG. 1. [Figure 6] It is a horizontal cross-sectional view similar to FIG. 1, schematically showing an example of the state when restarting molten salt electrolysis after stopping the molten salt electrolysis in the molten salt electrolysis apparatus of FIG. 1 and taking out the coiled titanium-based metal strip wound on the take-up reel. [Figure 7]This is a horizontal cross-sectional view showing an enlarged view of the other end of a leader strip that can be used in a molten salt electrolytic apparatus of another embodiment. [Modes for carrying out the invention]

[0027] Embodiments of this invention will be described in detail below with reference to the drawings. Note that some parts of the drawings are exaggerated for ease of understanding, and the actual dimensions, shapes, arrangements, and other configurations are not limited to those shown.

[0028] (Molten salt electrolysis apparatus) The molten salt electrolytic apparatus 1 illustrated in Figures 1 and 2 generally comprises an electrodeposition chamber 11 for forming a titanium-based metal strip TS by applying a voltage between electrodes in a molten salt bath Bm, a winding chamber 21 for feeding and winding the titanium-based metal strip TS formed in the electrodeposition chamber 11, and a connecting section 31 that connects the electrodeposition chamber 11 and the winding chamber 21. Figure 1 corresponds to a horizontal cross-sectional view of the cross-section along line II in Figure 2, viewed from a planar perspective.

[0029] Of these, the electrodeposition chamber 11 is divided into at least two spaces 11a and 11b by the partition wall 12b, for example, by the partition wall 12b, and has at least two spaces. The two spaces 11a and 11b are referred to as the pre-deposition space 11a and the main electrodeposition space 11b, respectively. Although not shown in the figures, there may be other spaces besides the pre-deposition space 11a and the main electrodeposition space 11b.

[0030] In the electrodeposition chamber 11, as shown in the horizontal cross-sectional view in Figure 1, a drum cathode 13 having a rotation axis 14 is provided, straddling both the pre-deposition space 11a and the main electrodeposition space 11b. In other words, the drum cathode 13 is provided as part of the partition wall 12b that separates the pre-deposition space 11a and the main electrodeposition space 11b, and the drum cathode 13, the pre-deposition space 11a, and the main electrodeposition space 11b are arranged such that a part of the outer peripheral surface 13a of the drum cathode 13 faces the pre-deposition space 11a, and at least a part of the remaining outer peripheral surface 13a faces the main electrodeposition space 11b. The rotation axis 14 of the drum cathode 13 can be erected at a position between the pre-deposition space 11a and the main electrodeposition space 11b, for example, slightly closer to the main electrodeposition space 11b in the illustrated example. In this configuration, the drum cathode 13 has a portion of its outer surface 13a that is slightly less than half of its circumferential direction facing the pre-deposition space 11a, and a portion of its outer surface 13a that is slightly more than half of its circumferential direction facing the main deposition space 11b.

[0031] When the drum cathode 13 rotates with the rotation axis 14 in the direction indicated by the arrow in Figure 1, the leader strip LS (see Figures 5, 6, etc.) and the titanium-based metal strip TS, which will be described later, peel off from the outer surface 13a of the drum cathode 13. Considering this peeling as starting from the position where the outer surface 13a of the drum cathode 13 is exposed to the molten salt bath Bm, the outer surface 13a of the drum cathode 13 sequentially passes through the starting point, the inter-electrodeposition space 11a, and the inter-electrodeposition space 11b, after which the titanium-based metal strip TS peels off from the outer surface 13a of the drum cathode 13, and returns to the starting point again. In other words, in the rotation of the drum cathode 13, the starting point is also the ending point, and the outer surface 13a of the drum cathode 13 can continue rotating beyond the starting point or the ending point. Then, after passing the starting point, the outer surface 13a of the drum cathode 13 re-enters the space between the electrodes of the pre-deposition space 11a, and a titanium-based metal strip TS is formed on its outer surface 13a. Focusing on a certain portion of the outer surface 13a of the drum cathode 13, if we define the direction in which this portion advances from the starting point due to the rotation of the drum cathode 13 as forward, then in Figure 1, of the two spaces 11a and 11b, the main deposition space 11b on the left is located in front of the pre-deposition space 11a on the right in the direction of rotation of the drum cathode 13. Since the outer surface 13a of the drum cathode 13 returns to the starting point after the titanium-based metal strip TS is peeled off, the furthest point in the direction of rotation is the starting point, and the furthest point is just before reaching the starting point. As the rotation of the drum cathode 13 continues, the pre-deposition space 11a will be located in front of the main deposition space 11b, with the starting point in between. Furthermore, as shown in the molten salt electrolytic apparatus 1 in Figure 1, the pre-deposition space 11a and the main electrodeposition space 11b can be positioned adjacent to each other, with the partition wall 12b and the drum cathode 13 in between.

[0032] Preferably, at least the curved outer peripheral surface 13a of the drum cathode 13, and typically the outer peripheral portion 13b of a predetermined thickness including the outer peripheral surface 13a, contain at least one element selected from the group consisting of Ti, Zr, Mo, and Nb. In particular, the outer peripheral surface 13a to the outer peripheral portion 13b may be made of titanium, zirconium, molybdenum, or niobium metal or an alloy thereof. The outermost surface (molten salt bath Bm side) of the outer peripheral surface 13a may be covered with a thin oxide film. This makes it easier to peel off the titanium-based metal strip TS formed on the outer peripheral surface 13a of the drum cathode 13, and also suppresses contamination of the titanium-based metal strip TS by the diffusion of elements from the material of the outer peripheral surface 13a.

[0033] The anodes 16a and 16b, which are paired with the drum cathode 13, contain an anode material that includes Ti. The anodes 16a and 16b are provided in the pre-deposition space 11a and the main deposition space 11b, respectively. Here, when it is necessary to distinguish between them, the anode 16a in the pre-deposition space 11a may be referred to as the anode 16a on the pre-deposition space 11a side, and the anode 16b in the main deposition space 11b may be referred to as the anode 16b on the main deposition space 11b side.

[0034] As shown in Figures 1 and 2, each anode 16a and 16b can be positioned around the drum cathode 13 in the pre-deposition space 11a and the main deposition space 11b, respectively, at a distance from the outer peripheral surface 13a of the drum cathode 13, and along a portion of the outer peripheral surface 13a of the drum cathode 13. One or both of the anode 16a on the pre-deposition space 11a side and the anode 16b on the main deposition space 11b side may be divided into multiple portions along the outer peripheral surface 13a of the drum cathode 13, for the purpose of facilitating replacement, etc., although this is not shown in the figures.

[0035] Both anodes 16a and 16b contain anode raw materials containing Ti. During molten salt electrolysis, Ti in the anode raw materials dissolves into the molten salt bath Bm, and this is electrodeposited onto the drum cathode 13 as a titanium-based metal. Therefore, at least a portion of the anode raw materials contained in each anode 16a and 16b is consumed as the Ti content gradually decreases with the continuation of molten salt electrolysis. For example, granular or powdered titanium-based raw materials, which are so-called consumable electrodes, may be used as anode raw materials and placed in an energizable cage-like container having numerous through-holes to constitute anodes 16a and / or 16b. In this case, anodes 16a and / or 16b include anode raw materials made of titanium-based raw materials and a cage-like container. The cage-like container may have an outer shape such as a plate curved in the circumferential direction of the drum cathode 13, and may be made of nickel, a nickel-based alloy, Hastelloy, or steel coated with nickel or a nickel-based alloy, and may have numerous through-holes. Alternatively, titanium-based raw materials obtained as ingots by melting and casting can be processed by hot or cold working as needed to form desired curved shapes, etc., and used as anode raw materials. In this case, anodes 16a and / or 16b may be composed solely of anode raw materials in curved shapes, etc. Furthermore, anode raw materials containing titanium-based raw materials with different compositions, such as oxygen content, may be used for anode 16a on the pre-deposition space 11a side and anode 16b on the main electrodeposition space 11b side.

[0036] Each anode 16a and 16b is connected to a power source outside the electrodeposition chamber 11 (not shown) by a conductor 16c or the like on its upper side, as shown in Figure 2, for example.

[0037] In the electrode configuration described above, which includes the drum cathode 13 and anodes 16a and 16b, when a voltage is applied between the electrodes while the drum cathode 13 is rotated together with the rotation axis 14, as each region of the outer circumferential surface 13a of the drum cathode 13 passes through the pre-deposition space 11a, titanium-based metal can be deposited on the outer circumferential surface region and adhere in a foil-like manner, as shown in Figure 1. Subsequently, as the outer circumferential surface region passes through the main deposition space 11b, the titanium-based metal that adhered in a foil-like manner to the outer circumferential surface region when passing through the pre-deposition space 11a becomes thicker due to further deposition of titanium-based metal on its surface. As the drum cathode 13 is rotated, the deposition of titanium-based metal in the pre-deposition space 11a and the main deposition space 11b continues, causing the titanium-based metal on the outer circumferential surface 13a of the drum cathode 13 to form a strip (i.e., a band), thereby forming a titanium-based metal strip TS on the outer circumferential surface 13a. From a macroscopic perspective, this titanium-based metal strip TS is strip-shaped, and from a microscopic perspective, although details will be described later, the outer surface is rough. The titanium-based metal strip TS passes between the main electrodeposition space 11b and the anode 16b, and is peeled away from the outer surface 13a of the drum cathode 13 by the tension caused by being wound up by the winding reel 22 in the winding chamber 21 (described later), and is sent to the winding chamber 21 through the communication section 31.

[0038] In order to continuously manufacture titanium-based metal strips TS, it is necessary to easily detach the titanium-based metal strips TS formed on the outer surface 13a of the drum cathode 13 from the outer surface 13a. Furthermore, in order to increase the manufacturing efficiency of titanium-based metal strips TS, it is necessary to form titanium-based metal strips TS with a certain thickness on the outer surface 13a of the drum cathode 13. In this embodiment, the electrodeposition chamber 11 is divided into a pre-deposition space 11a and a main electrodeposition space 11b, and the electrolytic conditions in the pre-deposition space 11a and the main electrodeposition space 11b can be appropriately adjusted so that the titanium-based metal is electrodeposited on the outer surface 13a of the drum cathode 13 in a relatively thin and easily detachable state in the pre-deposition space 11a, and its thickness can be increased in the main electrodeposition space 11b. As a result, mass production of titanium-based metal strips TS can be achieved.

[0039] Furthermore, the surface of the titanium-based metal strip TS, which originates from the titanium-based metal directly electrodeposited onto the outer surface 13a of the drum cathode 13 in the pre-deposition space 11a, that was in contact with the outer surface 13a of the drum cathode 13 becomes smooth, following the properties of the outer surface 13a of the drum cathode 13. On the other hand, in the main electrodeposition space 11b, in order to increase the thickness of the titanium-based metal on the drum cathode 13, the titanium-based metal may precipitate in a dendrite-like manner, and the outer surface of the titanium-based metal strip TS formed there tends to become somewhat rough.

[0040] The rotational drive force of the drum cathode 13's rotational shaft 14 is transmitted from a drive source (not shown). As can be seen in Figure 2, the drum cathode 13 is positioned with its rotational shaft 14 perpendicular to the bottom surface of the bottom wall portion 12d of the electrodeposition chamber 11. More precisely, the drum cathode 13 can be positioned with its rotational shaft 14 parallel to the vertical direction (up and down direction in Figure 2) (perpendicular to the bottom surface). This allows the upper side of the rotational shaft 14 to extend into the space above the bath surface Sm of the molten salt bath Bm where there is no molten salt (also called the "gas phase"), and to penetrate the ceiling portion 12c of the electrodeposition chamber 11. In this case, the only place where the rotational shaft 14 penetrates the ceiling portion 12c is in the gas phase portion filled with inert gas, etc., where there is no molten salt, thus simplifying the sealing structure. Although not shown in the diagram, if the drum cathode is positioned with its rotation axis lying horizontally and parallel to the horizontal direction, and the rotation axis penetrates the outer wall of the electrodeposition chamber in the molten salt bath, there is a concern that as the operating period lengthens, the drum cathode 13 and rotation axis 14 will bend due to gravity and other factors, causing the distance between the electrodes to become unstable. Furthermore, in this configuration, the outer wall needs to have a structure that prevents leakage of molten salt while allowing the rotation axis to penetrate and rotate, which significantly increases the difficulty of the equipment design. Moreover, in this case, if the rotation axis has a structure that penetrates the outer wall at each end, there will be two points of penetration in the molten salt bath, which also significantly increases the difficulty of the equipment design from this point of view. In the drum cathode 13 positioned with the rotation axis 14 in an upright direction as in the illustrated example, the upper side of the rotation axis 14 is connected to a drive source that may be provided outside the electrodeposition chamber 11.

[0041] On the other hand, the lower end portion 14a of the rotating shaft 14 of the drum cathode 13 is located at the bottom of the electrodeposition chamber 11. This lower end portion 14a may be a free end that is not restrained in any way, but it can be restrained by a oscillation suppression portion 15 in order to suppress unintended inward and outward oscillation in the radial direction when rotational driving force is transmitted to the rotating shaft 14. The oscillation suppression portion 15 can be configured to surround the lower end portion 14a rotatably without contact with it or in contact with at least a part of it when the rotating shaft 14 is stationary, without fixing the lower end portion 14a. For example, a recess formed on the inner surface of the bottom wall portion 12d, as shown in Figure 3(a), can be used as the oscillation suppression portion 15, or a member with a recess formed therein, as shown in Figure 3(b), can be attached to the bottom wall portion 12d to serve as the oscillation suppression portion 15.

[0042] The drum cathode 13 preferably has an energizing member 17 made of copper or a copper-based alloy containing Cu on the axial side of the outer peripheral surface 13a or outer peripheral portion 13b described above. In the case of an energizing member 17 made of a copper-based alloy, the energizing member 17 may contain one or more of the alloying elements Be, B, Na, Mg, Al, Si, P, Ti, Cr, Mn, Fe, Co, Ni, Zn, Y, Zr, Nb, Ag, Sn, Sb, Pt, and Au, and the total content of the alloying elements is preferably 10% by mass or less, and more preferably 7% by mass or less. A copper-based alloy means one in which the Cu content is 50% by mass or more. As shown in the figure, the energizing member 17 may be configured to include a cylindrical portion that contacts the inner peripheral surface of the outer peripheral portion 13b over almost its entire length, and a connecting portion that extends radially inward and connects the cylindrical portion to the rotating shaft 14, on the axial side of the outer peripheral portion 13b of the drum cathode 13. In this case, the rotating shaft 14 of the drum cathode 13 can also function as a conductor by electrically connecting it to a power source (not shown) outside the electrodeposition chamber 11, for example, on the upper side. When the current-carrying member 17 containing Cu is electrically connected to the outer peripheral portion 13b made of a different material, as described above, by direct contact, the current-carrying member 17, which has excellent conductivity, can suppress the increase in electrical resistance and the resulting heat generation, while achieving good peelability of the titanium-based metal strip from the outer peripheral surface 13a.

[0043] To suppress mutual diffusion between the material of the outer periphery 13b of the drum cathode 13 and the Cu of the current-carrying member 17, a sheet-like material containing Nb or the like may be interposed between the outer periphery 13b and the current-carrying member 17, although this is not shown in the figure.

[0044] Furthermore, it is preferable that the drum cathode 13 has a cooling section 18 inside. By cooling with the cooling section 18, it is possible to suppress an excessive temperature rise on the outer surface 13a of the drum cathode 13, thereby suppressing the strong adhesion of the titanium-based metal electrodeposited on the outer surface 13a in the pre-deposition space 11a and the resulting decrease in the peelability of the titanium-based metal strip TS.

[0045] The cooling section 18 can be a heat exchanger through which a cooling medium such as air, argon gas, or other gases or liquids such as water can flow, although this is not limited to the example shown. In the illustrated example, the cooling section 18 is a refrigerant flow path or refrigerant chamber provided inside the energizing member 17. In this case, a flow path (not shown) can be provided on the rotating shaft 14, thereby enabling the flow of the cooling medium between the cooling section 18 and the outside while preventing leakage of the cooling medium into the electrodeposition chamber 11.

[0046] Furthermore, the electrodeposition chamber 11 may be equipped with an atmosphere adjustment mechanism to adjust the internal atmosphere to that of an inert gas or the like.

[0047] As shown in Figure 1, the communication section 31 through which the titanium-based metal strip TS formed in the electrodeposition chamber 11 is sent to the winding chamber 21 is provided between the electrodeposition chamber 11 and the winding chamber 21. The communication section 31 communicates with both the electrodeposition chamber 11 and the winding chamber 21, but can be separated from them.

[0048] The communication section 31, which can be chamber-shaped or the like, is provided with a molten salt chamber filled with molten salt or the solidified salt thereof, and is configured so that a temperature gradient can be set so that the temperature of the molten salt decreases from the electrodeposition chamber 11 side to the winding chamber 21 side by placing a heater or cooler on the outside thereof. The molten salt provided in the communication section 31 may be substantially the same as the molten salt in the electrodeposition chamber 11, but may also be different.

[0049] More specifically, the temperature gradient that can be set in the communication section 31 is such that the temperature of the molten salt is higher than the melting point of the components of the molten salt near the inlet of the titanium-based metal strip TS on the electrodeposition chamber 11 side, but gradually decreases towards the outlet side of the titanium-based metal strip TS on the winding chamber 21 side, and becomes below the melting point near the outlet. As a result, in the communication section 31, the liquid phase of the molten salt at the inlet side becomes a state close to a solid phase with high viscosity as it moves towards the outlet side, and becomes almost a solid phase at the outlet, allowing the strip to pass through a relatively high temperature and relatively soft solid phase while preventing leakage of the molten salt.

[0050] Furthermore, in order to suppress leakage of molten salt into the winding chamber 21, it is preferable to provide a leakage suppression member 32 at the outlet of the communication section 31, surrounding the titanium-based metal strip TS that is sent from the outlet to the winding chamber 21. The leakage suppression member 32 further suppresses the leakage of molten salt that may adhere to the titanium-based metal strip TS into the winding chamber 21. The leakage suppression member 32 is preferably made of a material that has heat resistance, insulating properties, and sliding properties, and one example thereof is polyimide resin. At the outlet of the communication section 31, the titanium-based metal strip TS has passed through a temperature range in which the molten salt becomes a solid phase, and the temperature is cooled by heat dissipation from the winding chamber 21 side, so that the temperature falls below the heat resistance temperature of the material of the leakage suppression member 32, such as polyimide resin.

[0051] Incidentally, as mentioned earlier, even if the surface of the titanium-based metal strip TS that was in contact with the outer peripheral surface 13a of the drum cathode 13 becomes smooth, the outer peripheral surface tends to become rough. When such a titanium-based metal strip TS passes through the communication section 31, the rough outer peripheral surface may increase the sliding resistance as the titanium-based metal strip TS passes through the outlet of the communication section 31 where the molten salt is in a solid phase.

[0052] To address this, a molten salt electrolytic apparatus 51 of the embodiment shown in Figure 4 can be considered. In Figure 4, in the electrodeposition chamber 11, the main electrodeposition space 11b is expanded, and a drum cathode 43, each anode 46a and 46b, and a pre-electrodeposition space 41a, which are substantially the same as the drum cathode 13, each anode 16a and 16b, and the pre-electrodeposition space 11a, are provided in a horizontal cross-section of the figure with respect to the position of the outer peripheral surface of the titanium-based metal strip TS1 that has passed through the main electrodeposition space 11b, in a manner that is substantially symmetrical. In this molten salt electrolytic apparatus 51, the titanium-based metal strip TS1 formed on one drum cathode 13 and the titanium-based metal strip TS2 formed on the other drum cathode 43 overlap each other on their outer peripheral surfaces as they pass through the main electrodeposition space 11b, and are sent to the communication section 31 in that state. Therefore, the overlapping titanium-based metal strips TS1 and TS2 have the surfaces that were in contact with the smooth outer surfaces of the respective drum cathodes exposed to the outside, thereby reducing frictional resistance at the exit of the communication section 31. In the winding chamber 21, the titanium-based metal strips TS1 and TS2 are wound onto the winding reel 22 while remaining in an overlapping position. The other configurations of the molten salt electrolytic apparatus 51 can be the same as those of the molten salt electrolytic apparatus 1 shown in Figures 1 and 2, and are therefore omitted from this explanation.

[0053] A winding reel 22 is provided in the winding chamber 21. By rotating this winding reel 22, the titanium-based metal strip TS sent from the electrodeposition chamber 11 through the communication section 31 can be wound around the winding reel 22. As shown in Figures 1 and 2, the winding reel 22 can be configured to include a reel body 22a and a rotating shaft 22b that rotates the reel body 22a. This rotating shaft 22b may, for example, be connected to an external drive source (not shown) by passing through the ceiling on the upper side, as shown in Figure 2, similar to the rotating shaft 14 of the drum cathode 13 described above, and may be positioned vertically, but is not limited to this. If necessary, the lower end of the rotating shaft 22b may be restrained to some extent by a oscillation suppression section 15. The reel body 22a may be cooled internally by air cooling or water cooling.

[0054] The outer surface of the reel body 22a is preferably formed from a heat-resistant, non-conductive material such as polyimide resin. This suppresses power loss associated with current flow from the electrodes of the electrodeposition chamber 11. The interior of the reel body 22a is made of a high-strength metal material such as aluminum alloy, carbon steel, or stainless steel, thereby ensuring the required strength of the winding reel 22 with a small amount of material.

[0055] The titanium-based metal strip TS sent to the winding chamber 21 is at a relatively high temperature, and in order to suppress oxidation of it within the winding chamber 21, it is preferable to maintain an inert gas atmosphere inside the wall portion 21a that partitions the winding chamber 21. The winding chamber 21 may be provided with an atmosphere adjustment mechanism that can adjust the atmosphere inside to an inert gas atmosphere or the like. The molten salt electrolytic apparatus 1 may be equipped with a gas supply source that supplies gas such as an inert gas to the winding chamber 21 and the electrodeposition chamber 11. Furthermore, from the viewpoint of sufficiently suppressing the inflow of molten salt from the communication portion 31 into the winding chamber 21, it is preferable that the internal pressure of the winding chamber 21 be set higher than atmospheric pressure.

[0056] The winding chamber 21 can be provided with a cutting section 23, such as a shear, capable of cutting the titanium-based metal strip TS, before it reaches the winding reel 22 in the feed path of the titanium-based metal strip TS. When winding of the titanium-based metal strip TS on the winding reel 22 is completed, the cutting section 23 can be used to cut and separate the coiled titanium-based metal strip TS on the winding reel 22 from the portion remaining on the electrodeposition chamber 11 side.

[0057] (Method of manufacturing titanium-based metal strips) Molten salt electrolysis using the molten salt electrolytic apparatus 1 described above can be carried out, for example, as follows.

[0058] First, as shown in Figure 5, a leader strip LS can be stretched between the winding reel 22 of the winding chamber 21 and the drum cathode 13 of the electrodeposition chamber 11. One end of the leader strip LS can be wound around the winding reel 22, and the other end can be wound around the drum cathode 13. The leader strip LS functions to ensure that when molten salt electrolysis is started, the titanium-based metal strip TS formed around the drum cathode 13 is guided into the winding chamber 21 along with the other end of the leader strip LS and wound onto the winding reel 22 together with the leader strip LS. The other end of the leader strip LS wound around the drum cathode 13 may be a tapered end LS1, as shown in the embodiment in Figure 7, where the thickness gradually decreases towards the tip.

[0059] From the viewpoint of suppressing contamination of the titanium-based metal strip TS, it is preferable that the leader strip LS has substantially the same composition or material as the titanium-based metal strip TS obtained by molten salt electrolysis. The leader strip LS can be pre-formed to have a coil shape such that one end is smaller in diameter than the winding reel 22 and the other end is smaller in diameter than the drum cathode 13. As shown in Figure 5, the winding chamber 21 may be provided with tension rollers 24 such as loopers that can move to apply the required tension to the leader strip LS and titanium-based metal strip TS sent from the drum cathode 13 to the winding reel 22. The leader strip LS can have a different composition or material from the titanium-based metal strip TS. For example, if the leader strip LS is slightly softer and slightly thinner than the titanium-based metal strip TS obtained by molten salt electrolysis, the springback will be smaller and it will be easier to form a coil shape. Also, if a certain level of high strength is required for the leader strip LS, it is possible to make it from a material that is slightly harder than the titanium-based metal strip TS or to work harden it.

[0060] Next, while rotating the drum cathode 13 in the molten salt bath Bm of the electrodeposition chamber 11, a voltage is applied between the drum cathode 13 and the anodes 16a and 16b. At the same time, the winding reel 22 in the winding chamber 21 is also rotated. In the electrodeposition chamber 11, the application of voltage causes Ti to dissolve from the anodes 16a and 16b in the pre-deposition space 11a and the main electrodeposition space 11b, respectively, and this Ti is electrodeposited as a titanium-based metal on the outer circumferential surface 13a of the drum cathode 13 or on the surface of the leader strip LS. As a result, the titanium-based metal is deposited in a strip-like (i.e., band-like) manner on the outer circumferential surface 13a of the drum cathode 13, forming a titanium-based metal strip TS. In the pre-deposition space 11a, a thin, highly exfoliable titanium-based metal strip TS is formed on the outer circumferential surface 13a of the drum cathode 13, and in the main electrodeposition space 11b, more titanium-based metal is electrodeposited on top of it, causing the titanium-based metal strip TS to become significantly thicker.

[0061] As the drum cathode 13 and the winding reel 22 rotate, the leader strip LS is wound onto the winding reel 22, and the titanium-based metal strip TS, which has been continuously deposited in a strip shape following the end of the leader strip LS, is sent from the electrodeposition chamber 11 through the communication section 31 to the winding chamber 21. At this time, the titanium-based metal strip TS on the drum cathode 13 is subjected to tension from being wound onto the winding reel 22 in the winding chamber 21, and is sequentially peeled away from the outer surface 13a of the drum cathode 13 in the portion that has passed the anode 16b located in the main electrodeposition space 11b. As a result, the outer surface 13a of the drum cathode 13 comes into contact with the molten salt bath, and the outer surface 13a of the drum cathode 13 returns to its starting point in rotation.

[0062] Since the titanium-based metal strip TS is prone to peeling off from the drum cathode 13, in the pre-deposition space 11a, where the titanium-based metal is directly electrodeposited onto the outer surface 13a of the drum cathode 13, it is preferable to deposit the titanium-based metal in a thin foil-like manner on the outer surface 13a so as not to form deposits such as dendrites. On the other hand, from the viewpoint of improving the productivity of the titanium-based metal strip TS, it is preferable to make the deposition thickness of the titanium-based metal on the drum cathode 13 in the main deposition space 11b significantly thicker than the deposition thickness of the titanium-based metal in the pre-deposition space 11a. The deposition thickness of the titanium-based metal is measured along a normal line drawn on the outer surface 13a at a measurement position on the outer surface 13a of the drum cathode 13.

[0063] As the titanium-based metal strip TS passes through the communication section 31, the temperature gradient set in the molten salt within the communication section 31 causes the molten salt to be in a state close to a solid phase at the outlet side of the communication section 31, thus suppressing leakage of the molten salt from the outlet into the winding chamber 21. In addition, in the illustrated molten salt electrolytic apparatus 1, the molten salt on the surface of the titanium-based metal strip TS is removed by the leakage suppression member 32 provided at the outlet of the communication section 31 as it is sent to the winding chamber 21.

[0064] In the molten salt electrolytic apparatus 51 of the embodiment shown in Figure 4, the titanium-based metal strip TS1 formed on one drum cathode 13 and the titanium-based metal strip TS2 formed on the other drum cathode 43 are sent to the communication section 31 with their outer peripheral surfaces overlapping as they pass through the main electrodeposition space 11b. In the communication section 31, the flat surfaces of the overlapping titanium-based metal strips TS1 and TS2 that were in contact with the outer peripheral surfaces of the drum cathodes face outwards, thus reducing the frictional resistance as the titanium-based metal strips TS1 and TS2 pass through the outlet.

[0065] In the winding chamber 21, the leader strip LS and the titanium-based metal strip TS connected to it are sequentially wound onto the winding reel 22. At this time, by maintaining an inert gas atmosphere such as argon gas inside the winding chamber 21, oxidation of the titanium-based metal strip TS, which is at a relatively high temperature immediately after separation from the molten salt, can be suppressed inside the winding chamber 21.

[0066] As the molten salt electrolysis described above continues in the electrodeposition chamber 11, titanium-based metal is deposited on the drum cathode 13 in both the pre-deposition space 11a and the main electrodeposition space 11b, causing the inter-electrode distance between the drum cathode 13 and the anodes 16a and 16b to gradually decrease. The inter-electrode distance here refers to the shortest straight-line distance from the measurement position on the outer surface 13a of the drum cathode 13, or, if titanium-based metal is deposited on the outer surface 13a, to the anode 16a or 16b, along the normal line drawn at the measurement position on the outer surface 13a of the drum cathode 13, in a cross-section along the horizontal direction as shown in Figure 1. It is preferable that the inter-electrode distance remains almost constant without significant fluctuation in both the pre-deposition space 11a and the main electrodeposition space 11b. This makes it possible to manufacture a titanium-based metal strip TS that is homogeneous in the longitudinal direction. Furthermore, by shortening the inter-electrode distance to a certain extent, power loss due to electrical resistance in the molten salt bath Bm can be kept to a minimum. From this perspective, considering the amount of titanium-based metal deposited to narrow the inter-electrodeposition distance in the pre-deposition space 11a and the main electrodeposition space 11b, it is preferable to maintain the inter-electrodeposition distance between the drum cathode 13 and the anode 16a in the pre-deposition space 11a within the range of 0.2 mm or more and 3.0 mm or less, and the inter-electrode distance between the drum cathode 13 and the anode 16b in the main electrodeposition space 11b within the range of 0.3 mm or more and 10.0 mm or less.

[0067] Furthermore, if the molten salt electrolysis described above and the winding of the titanium-based metal strip TS in the winding chamber 21 are continued, the titanium-based raw materials for anodes 16a and 16b in the electrodeposition chamber 11 will be used up by the molten salt electrolysis. In this case, the titanium-based raw materials for anodes 16a and / or 16b may be replaced with new ones during the molten salt electrolysis. For example, although not shown in the diagram, a replacement container with adjustable internal atmosphere can be placed on the ceiling portion 12c of the electrodeposition chamber 11 and connected to the electrodeposition chamber 11, allowing the titanium-based raw materials to be replaced without exposing anodes 16a and / or 16b to the atmosphere. A portion of the ceiling portion 12c may be made openable and closable so that only one of the anodes 16a or 16b can be replaced. Also, if anodes 16a and 16b are divided into multiple parts, a portion of the ceiling portion 12c may be made openable and closable so that only a portion of them can be replaced. In this embodiment of the molten salt electrolytic apparatus 1, the drum cathode 13 is positioned vertically so that the rotation axis 14 is parallel to the vertical direction, and anodes 16a and 16b are provided to the sides of the drum cathode 13, thereby enabling the exchange of titanium-based raw materials in the vertical direction as described above.

[0068] As molten salt electrolysis continues, a sufficient amount of titanium-based metal is deposited in the electrodeposition chamber 11, and when a sufficiently long titanium-based metal strip TS is wound onto the winding reel 22 in the winding chamber 21, the current to the drum cathode 13 and anodes 16a and 16b is stopped in the electrodeposition chamber 11, and the titanium-based metal strip TS is cut using the cutting unit 23 inside the winding chamber 21. After the temperature inside the winding chamber 21 has decreased to a certain extent, the winding chamber 21 can be opened, and the coiled titanium-based metal strip TS on the winding reel 22 can be removed from the winding chamber 21.

[0069] Furthermore, if molten salt electrolysis is to be restarted afterward, as shown in Figure 6, the cut end Ec of the titanium-based metal strip TS, which extends from the drum cathode 13 in the electrodeposition chamber 11 through the communication section 31 to the winding chamber 21, is joined to the other end of the leader strip LS, and one end of the leader strip LS is wound onto the winding reel 22. Then, by rotating the drum cathode 13 and the winding reel 22, and applying a voltage between the drum cathode 13 and the anodes 16a and 16b, molten salt electrolysis can be restarted.

[0070] In the molten salt electrolysis described above, metallic smelting products obtained from the smelting of titanium ore and titanium scrap can be used as titanium-based raw materials to be included in the anodes 16a and 16b in the electrodeposition chamber 11 of the molten salt electrolysis apparatus 1. In order to reduce the content of impurity elements such as O, Al, Mg, Si, Fe, Ca, S, C, N, Ni, Cr, Sn, Cu, Mn, V, Nb, and Mo in such titanium-based raw materials, the above-described molten salt electrolysis can be performed.

[0071] The pre-deposition space 11a and the main deposition space 11b of the electrodeposition chamber are each used to store molten salt to form a molten salt bath Bm. 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 such as magnesium chloride (MgCl2) may be contained in amounts of, for example, 70 mol% or more, more specifically 90 mol% or more, or more specifically 95 mol% or more. The molten salt bath Bm is not limited to a chloride bath, and may also contain, in addition to or in place of, other metal halides, metal bromides, metal fluorides and / or metal iodides.

[0072] The composition of the molten salt bath Bm in the pre-deposition space 11a and the main deposition space 11b may be the same or different. Even if the bath compositions are different, the presence of the partition wall 12b and the drum cathode 13 allows for the maintenance of different bath compositions in the pre-deposition space 11a and the main deposition space 11b over a long period of time. In the pre-deposition space 11a, from the viewpoint of producing a titanium-based metal strip TS with high peelability, it is preferable to achieve a molten state at a lower temperature and to contain a high concentration of titanium ions, and the molten salt bath Bm may contain a ternary system, a quaternary system, or even more components. On the other hand, in the main deposition space 11b, it is preferable to use a high current density in order to make the titanium-based metal strip TS thicker, and it is possible to use a relatively high temperature, so a molten salt bath Bm composed of fewer components, such as a ternary system or a binary system, can be used. An example of the binary system is an NaCl-KCl bath, and an example of the ternary system is an NaCl-KCl-MgCl2 bath.

[0073] Furthermore, the molten salt bath Bm may contain divalent and / or trivalent titanium ions as needed. It may also contain titanium ions with a higher valency than trivalent. The valency of the titanium ions may change depending on the type of titanium compound included in the molten salt bath.

[0074] The titanium ion concentration in the molten salt bath Bm is preferably higher in the pre-deposition space 11a than in the main electrodeposition space 11b. In the pre-deposition space 11a, if the titanium ion concentration in the molten salt bath Bm is low, titanium ions will be depleted between the drum cathode 13 and the anode 16a on the pre-deposition space 11a side. This can cause the titanium-based metal deposited on the drum cathode 13 to form dendrites, which can lead to high temperatures due to localized current flow, causing the titanium-based metal to adhere to the drum cathode 13 and making it difficult to detach the titanium-based metal strip TS from the drum cathode 13. To suppress this, the titanium ion concentration in the molten salt bath Bm in the pre-deposition space 11a is preferably 3 moles or more and 20 moles or less. On the other hand, in the main electrodeposition space 11b, it is sufficient to make the titanium-based metal on the drum cathode 13 thick, and the deposition morphology is not important, so it is not necessary to have a titanium ion concentration in the molten salt bath Bm as high as in the pre-deposition space 11a.

[0075] Furthermore, the communication section 31 must be cooled to below the upper limit of the heat resistance temperature of the leakage suppression member 32 at its outlet side, while maintaining a molten state at its inlet side. The composition of the molten salt in the communication section 31 can be appropriately determined according to these requirements. In addition, since electrodeposition of titanium-based metals is not performed in the communication section 31, titanium ions are not required.

[0076] It is preferable that the temperature of the molten salt bath Bm be higher in the main electrodeposition space 11b than in the pre-deposition space 11a. Specifically, the temperature of the molten salt bath Bm in the pre-deposition space 11a can be set to 480°C or higher and less than 550°C, while the temperature of the molten salt bath Bm in the main electrodeposition space 11b can be set to 550°C or higher and 770°C or lower. By not setting the temperature of the molten salt bath Bm in the pre-deposition space 11a too low, solidification of the molten salt bath Bm can be suppressed, and by not setting it too high, good peelability of the titanium-based metal strip TS can be ensured, and evaporation of the molten salt bath Bm can be suppressed. By not setting the temperature of the molten salt bath Bm in the main electrodeposition space 11b too low, solidification of the molten salt bath Bm can be suppressed, and by not setting it too high, thermal energy loss can be avoided, the titanium-based metal strip TS can not be adhered to the drum cathode 13, and evaporation of the molten salt bath Bm can be suppressed.

[0077] During molten salt electrolysis, it is preferable to keep the current density of the drum cathode 13 in the pre-deposition space 11a relatively low, for example, lower than the current density of the drum cathode 13 in the main deposition space 11b. This suppresses the formation of dendrites in the titanium-based metal deposited on the outer surface of the drum cathode 13 in the pre-deposition space 11a, thereby improving the peelability of the titanium-based metal strip TS.

[0078] Furthermore, during molten salt electrolysis, if possible, current may be simultaneously applied to all of the anodes: the anode 16a of the pre-deposition space 11a, the anode 16b of the main deposition space 11b, and the drum cathode 13. However, in the molten salt electrolysis apparatus 1 of this embodiment, it may be difficult to simultaneously apply current to the anodes 16a and 16b for reasons such as the fact that the anodes 16a and 16b are provided separately in the pre-deposition space 11a and the main deposition space 11b, but the drum cathode 13 is common to both. In such cases, current can be alternately applied to the anode 16a and drum cathode 13 of the pre-deposition space 11a and the anode 16b and drum cathode 13 of the main deposition space 11b (that is, alternating periods of current being applied to the anode 16a and drum cathode 13 and periods of current being applied to the anode 16b and drum cathode 13). Furthermore, current may be continuously passed through the anodes 16a and 16b and the drum cathode 13, but it is particularly preferable that the current flowing through the drum cathode 13 and the anode 16a on the pre-deposition space 11a side be a pulsed current. This pulsed current means that a period of power interruption is provided in which the current value is set to zero, and periods of power interruption and periods of power interruption are repeated alternately. When a pulsed current is used, it is thought that a smooth titanium-based metal strip TS is formed due to the diffusion of titanium ions in the molten salt bath Bm when the power is interrupted, and that the titanium-based metal is deposited on the drum cathode 13 in the pre-deposition space 11a in a manner that makes it easy to peel off from the drum cathode 13. For example, current may be alternately passed through the anode 16a and the drum cathode 13 and the anode 16b and the drum cathode 13, with the current flowing through the anode 16a and the drum cathode 13 being a pulsed current, and the current flowing through the anode 16b and the drum cathode 13 being continuous. Furthermore, in both the pre-deposition space 11a and the main deposition space 11b, the current flowing through the anodes 16a and 16b and the drum cathode 13 may be pulsed currents. The drum cathode 13 may be continuously energized, or there may be a period of power outage between the period during which current flows through the anode 16a and drum cathode 13 and the period during which current flows through the anode 16b and drum cathode 13.

[0079] By performing molten salt electrolysis using the molten salt electrolytic apparatus 1, titanium-based metal strips TS made of metallic titanium or titanium alloy can be manufactured. In the case of titanium-based metal strips TS made of metallic titanium, the content of each of the following elements may be, for example, 0.1% by mass or less, preferably 0.01% by mass or less, and the oxygen content may be, for example, 0.2% by mass or less, preferably 0.10% by mass or less, and even more preferably 0.05% by mass or less. Furthermore, the amount of other impurities that inevitably mix in is permitted, and the remainder may be titanium. In the case of titanium-based metal strips TS made of metallic titanium, the composition may be that of so-called industrial pure titanium (for example, a composition corresponding to JIS H 4600 type 1 to type 4) or high-purity titanium. Alternatively, in the case of titanium-based metal strips TS made of titanium alloy, the aluminum content may be, for example, 3% by mass or less, preferably 2% by mass or less, and the oxygen content may be 0.3% by mass or less, preferably 0.15% by mass or less. This may apply when titanium, aluminum, and oxygen-containing smelting products are used as titanium-based raw materials. [Explanation of Symbols]

[0080] 1.51 Molten Salt Electrolysis Apparatus 11 Electrodeposition chamber 11a, 41a Pre-deposition space (space) 11b Main electrodeposition space (space) 12a Exterior wall 12b Bulkhead 12c Ceiling 12d Bottom wall 13, 43 Drum Cathode 13a Outer surface 13b Outer periphery 14 Rotation axis 14a Lower end 15. Oscillation suppression unit 16a, 16b, 46a, 46b anode 16c conductor 17 Conductive components 18 Cooling section 21 Rewinding Chamber 21a Wall section 22 reel 22a Reel body 22b Rotation axis 23 Cut section 24 Tension Rollers 31 Communication part 32 Leakage suppression member Bm molten salt bath Sm bath surface TS, TS1, TS2 Titanium-based metal strips Ec cut end LS Leader Strip

Claims

1. Molten salt electrolysis apparatus, The electrodeposition chamber has an electrode that includes a rotatable drum cathode with its rotation axis positioned vertically to the bottom surface, and electrodes that are positioned around the drum cathode at a distance from the outer surface of the drum cathode and contain an anode material containing Ti, and an electrodeposition chamber in which a titanium-based metal strip is formed on the outer surface of the drum cathode by applying a voltage between the electrodes in a molten salt bath. A winding chamber is provided, which can be adjusted to an inert gas atmosphere internally and has a winding reel for winding the titanium-based metal strip sent from the electrodeposition chamber, A connecting section that connects the electrodeposition chamber and the winding chamber, and through which the titanium-based metal strip sent from the electrodeposition chamber to the winding chamber passes. Equipped with, The electrodeposition chamber has a pre-deposition space and a main electrodeposition space through which the outer surface region of the drum cathode sequentially passes as the drum cathode rotates, and the anode is provided in the pre-deposition space and the main electrodeposition space, respectively. A molten salt electrolytic apparatus is provided inside the communication section, and a temperature gradient can be set such that the temperature of the molten salt decreases from the electrodeposition chamber side to the winding chamber side.

2. The molten salt electrolytic apparatus according to claim 1, wherein the outer circumferential surface of the drum cathode contains at least one selected from the group consisting of Ti, Zr, Mo, and Nb.

3. The molten salt electrolytic apparatus according to claim 1, wherein the drum cathode has an energizing member made of copper or a copper-based alloy on the axial side of the outer surface.

4. The molten salt electrolytic apparatus according to claim 1, wherein the drum cathode has a cooling section inside.

5. The molten salt electrolytic apparatus according to claim 4, wherein the cooling unit is a heat exchanger through which a cooling medium can flow.

6. The molten salt electrolytic apparatus according to claim 1, wherein the winding chamber has a cutting section capable of cutting the titanium-based metal strip before it reaches the winding reel in the feed path of the titanium-based metal strip.

7. A method for producing a titanium-based metal strip using a molten salt electrolytic apparatus according to any one of claims 1 to 6, With the drum cathode and the winding reel rotating, In the electrodeposition chamber, a voltage is applied between the electrodes in a molten salt bath to deposit a titanium-based metal in a strip-like manner onto the outer surface of the drum cathode, thereby forming a titanium-based metal strip. The titanium-based metal strip is peeled off from the outer surface of the drum cathode at the point where it passes between the main electrodeposition space and the anode, and is then sent from the communication section to the winding chamber, and, The titanium-based metal strip is wound onto the winding reel in the winding chamber. A method for manufacturing titanium-based metal strips, including

8. The method for manufacturing a titanium-based metal strip according to claim 7, wherein the temperature of the molten salt bath in the electrodeposition chamber is higher in the main electrodeposition space than in the pre-electrodeposition space.

9. A method for manufacturing a titanium-based metal strip according to claim 8, wherein the temperature of the molten salt bath in the pre-deposition space is 480°C or higher and less than 550°C, and the temperature of the molten salt bath in the main electrodeposition space is 550°C or higher and 770°C or lower.

10. A method for manufacturing a titanium-based metal strip according to claim 7, wherein an electric current is alternately passed through the anode and the drum cathode of the pre-deposition space and the anode and the drum cathode of the main electrodeposition space.

11. A method for manufacturing a titanium-based metal strip according to claim 7, wherein the inter-electrode distance between the drum cathode and the anode in the pre-deposition space is within the range of 0.2 mm or more and 3.0 mm or less, and the inter-electrode distance between the drum cathode and the anode in the main electrodeposition space is within the range of 0.3 mm or more and 10.0 mm or less.

12. The method for producing a titanium-based metal strip according to claim 7, wherein the molten salt bath contains divalent titanium ions and / or trivalent titanium ions, and the titanium ion concentration is higher in the pre-deposition space than in the main electrodeposition space.

13. A method for manufacturing a titanium-based metal strip according to claim 7, wherein the deposition thickness of the titanium-based metal in the main electrodeposition space on the outer surface of the drum cathode is made thicker than the deposition thickness of the titanium-based metal in the pre-deposition space.

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