Magnesium chloride suction tube, storage tank, method for using the magnesium chloride suction tube, and method for producing metallic magnesium.

Abstract

To provide a magnesium chloride suction tube, a storage tank, a usage method of the magnesium chloride suction tube, and a production method of a magnesium metal, in which a contamination of the magnesium metal to a magnesium chloride can be reduced when separating the magnesium chloride from a melt including the magnesium metal and the magnesium chloride.SOLUTION: A magnesium chloride suction tube 1 of the present invention is used for sucking a magnesium chloride from a magnesium chloride layer Lc of a melt MB that includes an upper-side magnesium metal layer Lm and a lower-side magnesium chloride layer Lc, those of which are separated in a storage tank 11. The suction tube comprises: an inner side tube 2 including a suction end part 2a for sucking the magnesium chloride; and an outer side tube 3 including a capture end part 3a for capturing the magnesium metal, the tube being arranged at least on the periphery of the suction end part 2a on its side of the inner side tube 2.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This invention relates to a magnesium chloride suction tube used by immersing it in a melt containing a magnesium metal layer on the upper side and a magnesium chloride layer on the lower side of a storage tank, a storage tank, a method of using the magnesium chloride suction tube, and a method for producing magnesium metal.

Background Art

[0002] In the production of titanium by the Kroll process, titanium tetrachloride is reduced with magnesium metal in a reduction vessel to produce metallic titanium. At this time, magnesium chloride produced as a by-product is subjected to electrolysis using a molten salt bath containing the magnesium chloride (so-called molten salt electrolysis) to produce magnesium metal and chlorine gas. The magnesium metal obtained by molten salt electrolysis is used again for the reduction of titanium tetrachloride.

[0003] For example, Patent Documents 1 to 3 describe the handling of magnesium chloride produced by the reduction of titanium tetrachloride.

[0004] Patent Document 1 describes a "magnesium chloride storage step" for storing magnesium chloride produced as a by-product in a molten state in a reduction step.

[0005] Patent Document 2 aims to "provide a container that suppresses the mixing of the melt on the upper layer side of an interface when extracting the melt on the lower layer side from the interface when two or more melts are present in the container", and proposes "a container that is sealable and has a pipe body disposed across the inside and outside of the container, with one end located outside the container, and a member for transferring a melt for transferring a molten metal or a molten salt, and the member for transferring the melt further has a flange at the other end located inside the container".

[0006] Patent Document 3 states that the objective is "to provide a high-temperature molten material transfer pipe structure that exhibits minimal thermal deformation and oxidative wear, thereby reducing repair costs, particularly in transfer pipes for high-temperature molten materials handled in the sponge titanium manufacturing process, such as in discharge pipes for molten magnesium chloride from reduction vessels." Patent Document 3 then proposes "a high-temperature molten material transfer pipe characterized by having a protective pipe concentrically provided inside or outside the transfer pipe, in a transfer pipe for high-temperature molten materials handled in the sponge titanium manufacturing process." [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2003-306789 [Patent Document 2] Japanese Patent Publication No. 2021-91941 [Patent Document 3] Japanese Patent Publication No. 2002-168375 [Overview of the project] [Problems that the invention aims to solve]

[0008] After the reduction of titanium tetrachloride, the magnesium chloride produced by the reduction reaction is recovered from the reduction vessel along with the unreacted metallic magnesium that was not used in the reduction reaction.

[0009] If magnesium chloride containing such metallic magnesium is used in molten salt electrolysis, the metallic magnesium obtained from the electrolysis will be contaminated by impurities such as nickel originating from the reduction vessel contained in the metallic magnesium. When metallic magnesium contaminated with impurities is used in the reduction of titanium tetrachloride, it may lead to a decrease in the purity of the metallic titanium produced by the reduction. Therefore, it is desirable to separate the metallic magnesium from the magnesium chloride recovered from the reduction vessel before using it in molten salt electrolysis.

[0010] To separate metallic magnesium from magnesium chloride, one approach is to leave them as a molten mass in a storage tank. Due to the difference in specific gravity, the metallic magnesium will float to the top while the magnesium chloride will sink to the bottom. This separates the molten mass into a metallic magnesium layer and a magnesium chloride layer within the storage tank. In this state, the magnesium chloride can be separated from the metallic magnesium and recovered by using a suction tube immersed in the molten mass to draw out the magnesium chloride from the magnesium chloride layer.

[0011] Here, when magnesium chloride is drawn from the magnesium chloride layer of the molten material, as the thickness of the magnesium chloride layer at the bottom decreases with the reduction in magnesium chloride, the liquid level of the molten material and the interface between the metallic magnesium layer and the magnesium chloride layer descend. In particular, as this interface approaches the suction end of the suction tube, which is located deeper than the interface, there is a problem in that the metallic magnesium from the metallic magnesium layer above is easily drawn into and mixed with the magnesium chloride drawn from the suction end.

[0012] The object of this invention is to provide a magnesium chloride suction tube, a storage tank, a method of using the magnesium chloride suction tube, and a method of producing metallic magnesium that can suppress the contamination of magnesium chloride with metallic magnesium when separating magnesium chloride from a molten body containing metallic magnesium and magnesium chloride. [Means for solving the problem]

[0013] After diligent study, the inventor devised a magnesium chloride suction tube with at least a double-tube structure, including an inner tube for suctioning magnesium chloride and an outer tube for capturing metallic magnesium. This ensures that even if metallic magnesium is drawn into the flow of magnesium chloride being drawn into the suction end around the end of the magnesium chloride suction tube in the molten material, the metallic magnesium, having a relatively low specific gravity, will float to the surface before reaching the suction end of the inner tube and be captured at the capture end of the outer tube. As a result, the mixing of metallic magnesium with the magnesium chloride being drawn into the inner tube is suppressed.

[0014] The magnesium chloride suction tube of this invention is used to suction magnesium chloride from a magnesium chloride layer in a molten body containing an upper layer of metallic magnesium and a lower layer of magnesium chloride separated from each other in a storage tank, and comprises an inner tube containing a magnesium chloride suction end, and an outer tube provided around at least the side of the inner tube on the suction end side, and containing a metallic magnesium capture end.

[0015] In the magnesium chloride suction tube described above, it is preferable that the suction end of the inner tube protrudes more than the capture end of the outer tube.

[0016] In the magnesium chloride suction tube described above, it is preferable that the outer tube has a length exceeding the thickness of the metallic magnesium layer in the molten body when the magnesium chloride suction tube is immersed in the molten body.

[0017] In the magnesium chloride suction tube described above, it is preferable that the outer tube includes a coating-breaking portion that breaks the coating formed on the surface of the metallic magnesium droplets present in the molten material.

[0018] The storage tank of this invention is used for storing a molten material containing magnesium chloride and metallic magnesium, and comprises a tank body and one of the above-mentioned magnesium chloride suction pipes attached to the tank body.

[0019] The method of using the magnesium chloride suction tube of this invention is a method of using any of the above magnesium chloride suction tubes, in a state where the suction end of the inner tube and the capture end of the outer tube are positioned on the bottom side of the storage tank rather than at the interface between the metal magnesium layer and the magnesium chloride layer, while sucking magnesium chloride by the inner tube, the metal magnesium is captured at the capture end of the outer tube.

[0020] The method for producing metallic magnesium of this invention is to perform molten salt electrolysis on the magnesium chloride taken out from the melt by the method of using the magnesium chloride suction tube described above, to produce metallic magnesium and chlorine gas.

Advantages of the Invention

[0021] According to this invention, it is possible to suppress the mixing of metallic magnesium into the magnesium chloride separated from the melt containing metallic magnesium and magnesium chloride.

Brief Description of the Drawings

[0022] [Figure 1] It is a cross-sectional view along the depth direction showing an example of a storage tank provided with the magnesium chloride suction tube of one embodiment of this invention. [Figure 2] It is an enlarged cross-sectional view of the main part of FIG. 1. [Figure 3] It shows the magnesium chloride suction tube of another embodiment. It is a view similar to FIG. 2. [Figure 4] It shows the magnesium chloride suction tube of still another embodiment. It is a view similar to FIG. 2. [Figure 5] It shows the magnesium chloride suction tube of still another embodiment. It is a view similar to FIG. 2. [Figure 6] It shows the magnesium chloride suction tube of still another embodiment. It is a view similar to FIG. 2.

Modes for Carrying Out the Invention

[0023] Embodiments of this invention will be described in detail below with reference to the drawings. The magnesium chloride suction tube 1 illustrated in Figure 1 may be installed in a storage tank 11 for storing a molten body MB containing magnesium chloride and metallic magnesium.

[0024] The storage tank 11 includes a magnesium chloride suction pipe 1 and a container-shaped tank body 12, as well as heaters, etc., which are not shown in the illustration and are arranged around the tank body 12 to heat the inside of the tank body 12. The illustrated tank body 12 has a cylindrical or other tubular side wall portion 12a, a plate-shaped bottom portion 12b such as a disc that seals the lower side of the side wall portion 12a, and a lid 12d that covers the opening 12c on the upper side of the side wall portion 12a of the tank body 12, but it is not limited to such a specific shape or structure as long as it can store the molten material MB. Furthermore, the storage tank 11 may have other members or parts that are not shown here.

[0025] In the storage tank 11, heating using the heaters mentioned above causes the magnesium chloride and metallic magnesium to melt, forming a molten body MB. If this molten state is maintained, the metallic magnesium, which has a relatively lower specific gravity, will float to the top, while the magnesium chloride, which has a relatively higher specific gravity, will sink to the bottom. As a result, the molten body MB in the storage tank 11 separates into an upper metallic magnesium layer Lm and a lower magnesium chloride layer Lc, as shown in the figure.

[0026] For the molten body MB containing the metallic magnesium layer Lm and the magnesium chloride layer Lc separated from each other by the specific gravity separation described above, magnesium chloride can be aspirated from the magnesium chloride layer Lc using the magnesium chloride suction tube 1.

[0027] Here, a magnesium chloride suction tube 1 with at least a double-walled tube structure having an inner tube 2 and an outer tube 3 is used. The inner tube 2 is for suctioning magnesium chloride, and a suction end 2a is provided at the end of the magnesium chloride suction tube 1 that is immersed in the molten material MB. Inside the inner tube 2, a suction space 2b is defined through which the magnesium chloride suctioned from the suction end 2a passes. The inner tube 2 may be connected to a pump (not shown) at the end of the magnesium chloride suction tube 1 that is located outside the storage tank 11, which is driven to suction magnesium chloride.

[0028] An outer tube 3 is provided around at least the suction end 2a of the inner tube 2, and in the illustrated example, around almost the entire circumference of the inner tube 2. The outer tube 3 is designed to capture metallic magnesium to prevent it from being drawn into the inner tube 2 from the suction end 2a, and includes a capture end 3a for this purpose. The space between the outer tube 3 and the inner tube 2 becomes a capture space 3b where metallic magnesium that enters from the capture end 3a accumulates. This capture space 3b may contain not only metallic magnesium but also magnesium chloride. The capture space 3b of the outer tube 3 may also be suctioned by a pump or the like, but suctioning the outer tube 3 is not necessarily required.

[0029] This magnesium chloride suction tube 1 can be used as described below. First, the suction end 2a and capture end 3a of the magnesium chloride suction tube 1 are positioned in the storage tank 11 at a location deeper than the interface IF between the metallic magnesium layer Lm and the magnesium chloride layer Lc of the molten body MB (on the bottom 12b side), that is, within the magnesium chloride layer Lc.

[0030] Next, magnesium chloride in the magnesium chloride layer Lc is drawn out through the suction end 2a into the suction space 2b. As magnesium chloride is drawn out of the magnesium chloride layer Lc, the amount of magnesium chloride in the magnesium chloride layer Lc decreases, and the thickness of the magnesium chloride layer Lc decreases. Consequently, the liquid level LF of the molten body MB drops. On the other hand, since the thickness of the metallic magnesium layer Lm does not change substantially, the interface IF between the metallic magnesium layer Lm and the magnesium chloride layer Lc also drops along with the drop in the liquid level LF.

[0031] As a result, the interface IF gradually approaches the suction end 2a and the capture end 3a of the magnesium chloride suction tube 1. Therefore, the metallic magnesium contained in the metallic magnesium layer Lm above the interface IF is drawn into the flow of magnesium chloride toward the suction end 2a around the suction end 2a and the capture end 3a, making it easier for it to mix with the magnesium chloride being drawn into the suction end 2a. Such entrainment of metallic magnesium can occur particularly significantly near the suction end 2a of the magnesium chloride. Consequently, although not shown in the diagram, if a suction tube with a single-walled tube structure having a suction end is used and magnesium chloride is drawn from the suction end, especially when the interface between the metallic magnesium layer and the magnesium chloride layer is located slightly above the suction end, not only magnesium chloride but also metallic magnesium will be drawn into the suction space 2b due to the entrainment of metallic magnesium as described above.

[0032] In contrast, the magnesium chloride suction tube of this embodiment is provided with an outer tube 3. By providing the outer tube 3, metallic magnesium, which would otherwise be drawn into the suction end 2a along with the magnesium chloride, floats up before reaching the suction end 2a due to its low specific gravity, as shown by the arrow in Figure 2, and can be captured by the capture end 3a of the outer tube 3 without reaching the suction end 2a. As a result, the mixing of metallic magnesium with the magnesium chloride drawn into the inner tube 2 from the suction end 2a is suppressed.

[0033] The outer tube 3 includes a capture end 3a located around at least the suction end 2a side of the inner tube 2, and as long as it has a length equal to the length of the capture end 3a, it is possible to capture metallic magnesium as described above.

[0034] On the other hand, as in the illustrated embodiment, when the magnesium chloride suction tube 1 is immersed in the molten body MB, if the outer tube 3 has a length exceeding the thickness of the metallic magnesium layer Lm of the molten body MB and extends above the liquid surface LF, the molten body MB may enter the capture space 3b between the outer tube 3 and the inner tube 2 from the capture end 3a until it reaches, for example, the same height as the liquid surface LF or above the liquid surface LF. In this state, when magnesium chloride is aspirated, if metallic magnesium is captured at the capture end 3a, the metallic magnesium will float upward in the capture space 3b as shown in the illustration, due to the magnesium chloride located below it. Therefore, in this case, the possibility of metallic magnesium, once captured at the capture end 3a, flowing out of the capture end 3a and being drawn into the suction end 2a can be sufficiently reduced. If the outer tube 3 extends above the liquid surface LF, a large amount of metallic magnesium can be captured in the capture space 3b.

[0035] Although not shown in the diagram, a triple or higher tubular structure may be created by providing additional tubular members around the outer tube. In this case as well, the outer tube and the outermost tubular members will enable the capture of metallic magnesium.

[0036] The suction end 2a of the inner pipe 2 is preferably positioned to protrude more than the capture end 3a of the outer pipe 3 towards the bottom 12b of the storage tank 11 when immersed. In other words, it is preferable that the suction end 2a has a protruding portion 2c that extends from the end face of the capture end 3a. When the suction end 2a has a protruding portion 2c, the metallic magnesium that floats up while being caught in the flow of magnesium chloride is prevented from reaching the suction end 2a by the peripheral wall of the protruding portion 2c, and is more likely to enter the surrounding capture end 3a.

[0037] However, as shown in the embodiment in Figure 3, the suction end 2a may not have a protruding portion 2c, and the end face of the suction end 2a and the end face of the capture end 3a may be substantially on the same plane. Note that if the suction end 2a is located further back than the capture end 3a (i.e., if the capture end 3a protrudes further than the suction end 2a), metallic magnesium caught in the magnesium chloride flow may be more likely to reach the suction end 2a before floating up in the capture space 3b.

[0038] Incidentally, in the molten body MB, the majority of the metallic magnesium is in a liquid or molten state, forming the metallic magnesium layer Lm, but a small portion may exist as droplets or molten granules. It is thought that these metallic magnesium droplets are separated from the majority of the liquid metallic magnesium by the formation of a film of oxide or the like on their surface, due to contact with oxygen in the air before or during the storage of the molten body MB in the storage tank 11.

[0039] In particular, tiny droplets of metallic magnesium tend not to float upwards and remain suspended within the molten body MB. Therefore, near the interface IF, they tend to be drawn into the flow of magnesium chloride being drawn to the suction end 2a and easily become mixed into the magnesium chloride. To suppress the mixing of such tiny droplets, it is desirable to break the coating formed around the droplets. When the coating on a droplet is broken, it is thought that the droplet will aggregate or combine with other droplets to form a somewhat larger droplet, or be incorporated into the metallic magnesium layer Lm. Since larger droplets tend to float, they are less likely to be drawn to the suction end 2a along with the magnesium chloride.

[0040] From this perspective, it is preferable that the outer tube 3 includes a coating-breaking section that breaks the coating formed on the surface of the metallic magnesium droplet. Specific examples of the coating-breaking section are shown in Figures 4 to 6.

[0041] In the example shown in Figure 4, the leading edge of the capture end 3a is made into a mesh-like portion 3c. In this way, metallic magnesium droplets that become entangled in the flow of magnesium chloride drawn into the suction end 2a come into contact with the mesh-like portion 3c, causing their coating to be destroyed. As a result, these droplets gather together with other droplets, and their suction to the suction end 2a is suppressed.

[0042] In Figure 5, the outer surface of the leading edge of the capture end 3a is made rougher than the surface of the other parts, creating an outer surface uneven portion 3d. Because the outer surface of the outer surface uneven portion 3d is rougher than the other parts, it can effectively break the coating of metallic magnesium droplets that come into contact with it. For example, the outer surface of the outer surface uneven portion 3d may have a repeating pattern of irregularities with a height of 0.1 mm or more and a height of 10 mm or less. The surfaces of the other parts may be formed by normal finishing processes and only need to be smoother than the outer surface of the outer surface uneven portion 3d.

[0043] The outer tube 3 in Figure 6 has a drive source, not shown in the figure, located outside the storage tank 11, which acts as a coating destruction point. This drive source causes the outer tube 3 to vibrate using ultrasonic vibrations or the like. The vibration direction can be any direction, including the up and down direction shown by the white arrows in the figure, the left and right directions, or directions inclined relative to those directions. The vibration direction is not limited to the direction shown in the figure and can be changed as appropriate. When the outer tube 3 vibrates, the coating on the metallic magnesium droplets in contact with it can be destroyed relatively easily.

[0044] The materials used to make up the inner tube 2 and the outer tube 3 are not particularly limited, but can include, for example, stainless steel, carbon steel, titanium, silicon nitride, etc.

[0045] In a storage tank 11 equipped with a magnesium chloride suction tube 1, the magnesium chloride suction tube 1 is often fixedly attached to the tank body 12 or lid 12d, etc. However, it may also be attached in a way that allows the magnesium chloride suction tube 1 to move, so that the position of the suction end 2a and the capture end 3a in the depth direction can be changed.

[0046] The storage tank 11 is typically a tank (a so-called reservoir) for storing the molten material MB recovered from the reduction vessel where titanium tetrachloride reduction has been performed, until it is used in molten salt electrolysis.

[0047] However, the storage tank 11 may be any container-like object for storing the molten body MB, and may be something other than the reservoir described above, and may even be a movable container such as a so-called container.

[0048] As described above, the magnesium chloride extracted from the molten MB can be decomposed into metallic magnesium and chlorine by molten salt electrolysis. This produces metallic magnesium. The metallic magnesium produced in this way contains almost no impurities such as nickel originating from the reduction vessel, because the metallic magnesium was sufficiently separated from the magnesium chloride subjected to molten salt electrolysis. As a result, when titanium tetrachloride is reduced using the metallic magnesium produced by the above molten salt electrolysis, metallic titanium with fewer impurities and high purity can be obtained. [Examples]

[0049] Next, a prototype magnesium chloride suction tube of this invention was fabricated and its effects were confirmed, which are described below. However, this description is for illustrative purposes only and is not intended to be limiting.

[0050] (Test Example 1) After reducing titanium tetrachloride in the reduction container, the 3000 kg of molten material remaining in the reduction container was removed from a container with a volume of 5 m³. 3 It was transferred to a storage tank. The molten material contained, by mass, 30% by mass of metallic magnesium and 70% by mass of magnesium chloride.

[0051] When the molten material was placed in a storage tank and kept at a temperature within the range of 750°C to 800°C for two hours, the molten material separated into an upper layer of metallic magnesium and a lower layer of magnesium chloride.

[0052] Subsequently, in Example 1, magnesium chloride was aspirated from the magnesium chloride layer of the molten material in the storage tank using a stainless steel magnesium chloride suction tube (double-walled tube structure) as shown in Figure 1. The magnesium chloride suction tube had an inner diameter of 5 cm and an outer diameter of 6 cm for the inner tube, an inner diameter of 10 cm and an outer diameter of 11 cm for the outer tube, and a projection height of 1 cm for the protruding portion.

[0053] The magnesium chloride supply pipe used in Example 2 was the same as that in Example 1, except that it had a triple-tube structure in which a pipe member with an inner diameter of 16 cm and an outer diameter of 17 cm was further provided around the outer pipe.

[0054] The magnesium chloride supply pipe used in Example 3 was the same as that in Example 1, except that a mesh-like portion (coating break section) was provided on the outer pipe, as shown in Figure 4. The mesh-like portion was made of the same stainless steel as the suction pipe, and the mesh opening size was 10 mm.

[0055] The magnesium chloride supply pipe used in Comparative Example 1 was the same as that in Example 1, except that it had a single-walled pipe structure without an outer pipe.

[0056] Molten salt electrolysis was performed using magnesium chloride recovered from the storage tank in each of Examples 1-3 and Comparative Example 1. The molten salt bath in the electrolytic cell for this molten salt electrolysis contained 13-25% by mass of MgCl2, with the remainder being CaCl2 and NaCl, and the temperature was maintained within the range of 650°C to 700°C during electrolysis. There were 7 anodes and 7 cathodes, and 2 bipolar plates between the anode and cathode. During molten salt electrolysis, magnesium chloride recovered from the storage tank was replenished in the electrolytic cell at appropriate timings. The amount and timing of magnesium chloride replenishment were the same in Examples 1-3 and Comparative Example 1.

[0057] Table 1 shows the probability of temporary short circuits occurring when the above molten salt electrolysis is continued for one year. This short circuit occurs when droplets or particles of metallic magnesium accumulate on the electrode surface and grow. The probability is expressed as a percentage of the total number of magnesium chloride replenishments in which a short circuit occurred within 20 minutes of the magnesium chloride replenishment. For example, if magnesium chloride is replenished 10 times and a short circuit occurs within 20 minutes of the replenishment in 5 of those replenishments, the short circuit probability is 50%. Note that one or more short circuits may occur during replenishment, but the above probability is the percentage of replenishments in which one or more short circuits occurred, regardless of the number of short circuits per replenishment. It is thought that the above short circuits are more likely to occur as the amount of metallic magnesium in the magnesium chloride used for molten salt electrolysis increases.

[0058] [Table 1]

[0059] As can be seen from Table 1, the probability of short circuits occurring during molten salt electrolysis was high in Comparative Example 1, while it was kept low in Examples 1 to 3. This is thought to be because, in Examples 1 to 3, a magnesium chloride suction tube with a double or more tubular structure was used to recover magnesium chloride from the storage tank, thereby appropriately suppressing the contamination of the magnesium chloride used in molten salt electrolysis with metallic magnesium.

[0060] These results show that the magnesium chloride suction tube of this invention can suppress the contamination of magnesium metal with magnesium chloride separated from the molten material.

[0061] (Test Example 2) Molten salt electrolysis was performed using magnesium chloride containing 10% by mass of metallic magnesium. The metallic magnesium contained in this magnesium chloride contained 400 ppm by mass of nickel. The conditions for molten salt electrolysis were substantially the same as those in Test Example 1. After molten salt electrolysis, the nickel content of the metallic magnesium obtained was found to be 110 ppm by mass.

[0062] Subsequently, titanium tetrachloride was reduced in a reduction vessel using the metallic magnesium obtained from the molten salt electrolysis described above. The metallic titanium (sponge titanium) obtained from this reduction contained 103 ppm by mass of nickel.

[0063] On the other hand, molten salt electrolysis and reduction were carried out in the same manner as described above, except that the metallic magnesium content of the magnesium chloride used in molten salt electrolysis was 0.1% by mass. In this case, the nickel content of the metallic magnesium obtained by molten salt electrolysis was 2 ppm by mass, and the nickel content of the metallic titanium (sponge titanium) obtained by reduction was 2 ppm by mass.

[0064] From the above, it was found that reducing the metallic magnesium content of the magnesium chloride used in molten salt electrolysis is important in order to obtain high-purity metallic titanium. [Explanation of Symbols]

[0065] 1. Magnesium chloride suction tube 2 Inner tube 2a Suction end 2b Suction space 2c protruding part 3 Outer tube 3a Captured end 3b Capture space 3c Mesh-like part 3d outer surface irregularities 11 Storage tank 12 Tank body 12a Side wall part 12b bottom 12c opening 12d lid body IF interface LF liquid level Lc magnesium chloride layer Lm metallic magnesium layer MB molten

Claims

1. A magnesium chloride suction tube used to draw magnesium chloride from the magnesium chloride layer in a molten body comprising an upper metallic magnesium layer and a lower magnesium chloride layer separated from each other in a storage tank, A magnesium chloride suction tube having an inner tube containing a magnesium chloride suction end, and an outer tube provided around at least the side of the inner tube that contains a metallic magnesium capture end.

2. The magnesium chloride suction tube according to claim 1, wherein the suction end of the inner tube is positioned to protrude more than the capture end of the outer tube.

3. The magnesium chloride suction tube according to claim 1, wherein, when the magnesium chloride suction tube is immersed in the molten body, the outer tube has a length exceeding the thickness of the metallic magnesium layer of the molten body.

4. The magnesium chloride suction tube according to claim 1, wherein the outer tube includes a coating-breaking portion that breaks a coating formed on the surface of a droplet of metallic magnesium present in the molten body.

5. A storage tank used for storing molten materials containing magnesium chloride and metallic magnesium, A storage tank comprising a tank body and a magnesium chloride suction pipe according to any one of claims 1 to 4 attached to the tank body.

6. A method using a magnesium chloride suction tube according to any one of claims 1 to 4, With the suction end of the inner tube and the capture end of the outer tube positioned on the bottom side of the storage tank, beyond the interface between the metallic magnesium layer and the magnesium chloride layer, A method for using a magnesium chloride suction tube, wherein while magnesium chloride is aspirated by the inner tube, metallic magnesium is captured at the capture end of the outer tube.

7. A method for producing metallic magnesium, comprising performing molten salt electrolysis on magnesium chloride extracted from the molten body using the method of using the magnesium chloride suction tube described in claim 6, thereby generating metallic magnesium and chlorine gas.

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