JP6784746B2 - Manufacturing method of metal container or tube, sponge titanium, and manufacturing method of titanium processed product or cast product - Google Patents

Description

The present invention relates to a metal container or tube used for producing titanium sponge by a reduction reaction between titanium tetrachloride and metallic magnesium, a method for producing titanium sponge, and a method for producing a processed titanium product or a cast product, in particular, a metal. Regarding a metal container or tube, a method for producing titanium sponge, and a method for producing a processed titanium product or a cast product, which prevents contamination by impurities from the container and / or tube and enables the production of high-purity titanium sponge. ..

Titanium sponge is industrially produced by the Kroll process. The titanium sponge titanium manufacturing process by the Kroll process can be roughly divided into four processes: a liquid forming process, a reduction separation process, a crushing process, and an electrolysis process.
The reduction separation step, which is one of these steps, comprises a reduction step and a vacuum separation step. In the reduction step, titanium tetrachloride is dropped onto molten metallic magnesium in a stainless steel or steel reaction vessel to cause a reduction reaction, and sponge titanium is produced. Further, in the vacuum separation step, the sponge titanium produced in the reduction step is evacuated at a high temperature and under reduced pressure to produce sponge titanium from which residual magnesium chloride and metallic magnesium have been removed. (Non-Patent Document 1)

The inner wall, which is the inner surface of the reaction vessel for producing titanium sponge used in the reduction separation step (hereinafter, simply referred to as the reaction vessel) and the container for storing and transferring molten metallic magnesium, is made of stainless steel or low carbon steel. Therefore, at high temperatures, impurity metals such as iron, nickel, and chromium elute from the inner wall of the container, causing a decrease in the purity of titanium sponge and metallic magnesium. In particular, in an unused reaction vessel, the elution of impurity metals is conspicuous.
In addition, these from the metal tubes used during the reduction separation step, during the transfer of the molten metallic magnesium to the reaction vessel, and during the removal of the molten magnesium chloride and metallic magnesium by vacuum separation. Elution of impurity metals into molten metal and / or metal salts also causes a decrease in the purity of titanium sponge and magnesium metal.

When the impurity metal elutes from the metal container and / or tube to the sponge titanium, the decrease in purity is particularly remarkable in the outer peripheral portion of the sponge titanium, and it becomes necessary to remove the outer peripheral portion of the sponge titanium in which the decrease in purity has occurred. ..
The value of low-purity titanium sponge is significantly lower than that of high-purity titanium for aircraft. Therefore, it is necessary to produce titanium sponge with higher purity.

As one of the methods for preventing such contamination of sponge titanium from the reaction vessel by an impurity metal, Patent Document 1 states that titanium, which is the same metal as the generated metal, is evaporated in the reaction vessel and deposited on the inner wall of the vessel. Thereby, a method of forming an alloy layer of titanium and a metal forming the reaction vessel on the inner wall of the reaction vessel to prevent contamination by impurity metals is described.

Further, Patent Document 2 also describes an invention of a method for preventing contamination of a sponge titanium reaction vessel by an impurity metal. In the present invention, when an unused reaction vessel is used, crushed particles of high chlorine sponge titanium are loaded and the temperature is raised to a high temperature to form a reaction vessel on the inner wall of the reaction vessel. It is an invention of a method of forming an alloy layer and preventing contamination by an impurity metal at a level equivalent to that of a reaction vessel already used.

In each of these prior arts, an alloy of the metal forming the reaction vessel and the metal (titanium, etc.) produced in the reaction vessel is previously applied to the inner wall of the reaction vessel before the first use of the unused reaction vessel. It discloses that it is formed. By doing so, an alloy layer equivalent to the alloy layer naturally formed in the reaction vessel used in several reduction separation steps can be intentionally formed on the inner wall of the unused reaction vessel. Then, by using this reaction vessel, the metal (titanium sponge, etc.) generated by the reaction comes into contact with the alloy layer formed on the inner wall of the reaction vessel, and the impurity metal (metal forming the reaction vessel, etc.) It is possible to prevent contamination by.

However, although the method of the above-mentioned prior art in which the alloy layer is formed on the inner wall of the reaction vessel can reduce the contamination of the produced metal by the impurity metal to some extent, the contamination has not been significantly reduced.
Further, in the method of the above prior art, the alloy layer of the metal forming the reaction vessel and titanium can be formed only in the reaction vessel, and the effect of preventing contamination by the impurity metal is limited to the reaction vessel only. It ends up. Further, in these methods, a molten state is formed by a metal container for storing or transferring molten metallic magnesium used for reduction of titanium tetrachloride, and a metal forming a metal tube used for the reduction reaction. It is not possible to prevent the contamination of magnesium chloride and metallic magnesium.

Therefore, in order to aim for further purification of the metal produced by the reaction, particularly titanium sponge, it is superior to the method of the above-mentioned prior art for forming an alloy layer between the metal forming the inner wall of the container and the generated metal. There is a need for a method that has a pollution-preventing effect and can be performed in a short time.

Resources and Materials Vo. 1.109 P1157-1163 (1993)

JP-A-2009-127107 JP-A-2014-214356

The present invention solves the above problems, and the impurity metal to titanium sponge is removed from the inner wall of the metal container and / or tube used in the method for producing titanium sponge by the reduction reaction between titanium tetrachloride and metallic magnesium. An object of the present invention is to provide a method for producing a metal container or tube, a titanium sponge, and a method for producing a processed titanium product or a cast product, which can effectively solve the problem of elution.

As a result of diligent studies by the present inventors in order to solve the above problem, it is generated by using a metal container and / or a tube having a titanium film in at least a part of a portion in contact with a molten metal or the like. We have found that the prevention of contamination by the impurity metal of titanium sponge is significantly improved, and have completed the present invention.

The present invention has been made based on such findings, and is as follows.
[1] A metal container or tube used for producing titanium sponge by a reduction reaction between titanium tetrachloride and metallic magnesium, which has a titanium film on at least a part of an inner wall.
[2] The metal container or tube according to the above [1], wherein the thickness of the titanium film is 0.02 mm or more.
[3] The above-mentioned [1] or [2], wherein the titanium film is formed at a portion in contact with molten metallic magnesium, molten magnesium chloride or sponge titanium, or a mixture of two or more thereof. Metal container or tube.

[4] A method for producing sponge titanium by a reduction reaction between titanium tetrachloride and metallic magnesium, which is in contact with molten metallic magnesium, molten magnesium chloride or produced sponge titanium, or a mixture of two or more thereof. A method for producing titanium sponge, using a metal container and / or a tube having a titanium film on at least a part of the portion.
[5] The method for producing sponge titanium according to the above [4], wherein the thickness of the titanium film is 0.02 mm or more.
[6] The titanium film is formed by applying a paste containing titanium powder, titanium hydride powder, or both to the inner wall of a metal container and / or a tube and heat-treating the above [4] or [5]. ]. The method for producing titanium sponge.

[7] A method for producing a processed titanium product or a cast product, using sponge titanium produced by the production method according to any one of the above [4] to [6].

The method for producing a metal container or tube and sponge titanium of the present invention is to produce sponge titanium from a metal container and / or tube, and to magnesium chloride and metallic magnesium in a molten state to be stored and transferred. It has the effect of preventing the elution of impurity metals. Since the sponge titanium obtained by the production method of the present invention has high purity, it is suitable as a raw material for various processed titanium products or cast products. The metal container and / or tube used in the production method of the present invention is also suitable as a member that comes into contact with molten magnesium, molten magnesium chloride or titanium sponge, or a mixture of two or more thereof. ..

It is a schematic diagram for demonstrating the titanium film by one Embodiment of this invention.

In the reduction reaction between titanium tetrachloride and metallic magnesium in the method for producing sponge titanium of the present invention, the metallic magnesium is melted from the metallic vessel for storing magnesium after the metallic reaction vessel is made into an inert atmosphere. In the reduction process of producing sponge titanium and magnesium chloride by charging using a metal tube and dropping titanium tetrachloride to the charged metallic magnesium, and then metal from the reaction vessel. This is a reaction consisting of a vacuum separation step in which magnesium chloride and unreacted metallic magnesium are vacuum-separated to obtain titanium sponge through the tube. In the reduction step, molten metallic magnesium is filled in a metallic reaction vessel kept at a high temperature, and titanium tetrachloride is dropped therein to reduce titanium tetrachloride with magnesium, resulting in a metallic reaction. Titanium sponge is formed on the rostrum in the container.

Since magnesium chloride is produced as a by-product in the reduction step, it is appropriately extracted from the reaction vessel, but it cannot be completely extracted, and even after the process is completed, this magnesium chloride is a metallic reaction together with unreacted metallic magnesium. Remains in the container. The vacuum separation step removes these from the titanium sponge.
Further, in the vacuum separation step, a metal reaction vessel containing the produced titanium sponge and an empty metal reaction vessel are arranged adjacent to each other, and the upper portions of the two are connected to each other by a metal pipe. Then, by vacuuming the inside of the latter metal reaction vessel while heating the former metal reaction vessel from the outside, metallic magnesium and magnesium chloride contained in the sponge titanium in the former metal reaction vessel are formed. Is moved into an empty metal reaction vessel in a gaseous and / or molten state through the metal tube. The metallic magnesium transferred into the empty metallic reaction vessel is used again in the reduction step. In addition, magnesium chloride that has also been moved into an empty metal reaction vessel is returned to metallic magnesium by an electrolysis reaction and reused in the reduction step.

The metal container and / or tube used in the method for producing titanium sponge of the present invention includes at least a portion of contact with molten metallic magnesium, molten magnesium chloride or produced titanium sponge, or a mixture of two or more thereof. It has a titanium film in part. By providing such a titanium film, the diffusion rate of the impurity metal eluted from the metal container and / or the tube can be suppressed, and not only the sponge titanium but also the molten metallic magnesium and the molten magnesium chloride. Contamination by impurity metals can be reduced. Therefore, the contamination of the finally produced titanium sponge with the impurity metal can be significantly reduced.

The titanium film of the present invention is a layer formed of metallic titanium. For example, in the case of a metal reaction vessel in which titanium powder paste is applied to the inner wall of the vessel and heat-treated, as shown in FIG. 1, the boundary between the metal reaction vessel inner wall 1 and the titanium film 3 is formed. The alloy layer 2 formed by mutual diffusion between the metal and titanium on the inner wall of the reaction vessel made of metal is formed. In the titanium film of the present invention, a portion having a titanium concentration of 75% or more is defined as the titanium film of the present invention. The titanium concentration referred to here is calculated by the following formula from the measurement results of each metal measured using an electron probe microanalyzer (SUPERPROBE JXA-8100, manufactured by JEOL Ltd.).
(Ti concentration) (%)
= (Mass% of Ti) / {(Mass% of Ti) + (Mass% of Ni) + (Mass% of Fe) + (Mass% of Cr)}
× 100

The thickness of the titanium film of the present invention is measured by the following method. An electron probe microanalyzer (SUPERPROBE JXA-8100, manufactured by JEOL Ltd.) was used as a measurement sample for a part of the inner wall (about 1 cm x 1 cm x 1 cm square) of a metal container or tube on which a titanium film was formed. The cross section is measured, and the thickness of the titanium film in the measurement sample is measured at 10 points. Then, the minimum value among the 10 points is taken as the thickness of the titanium film.

The thickness of the titanium film is preferably 0.02 mm or more, more preferably 0.02 mm or more and 5 mm or less, further preferably 0.1 mm or more and 5 mm or less, further preferably 0.3 mm or more and 5 mm or less, and 0. 7 mm or more and 5 mm or less are more preferable, and 2 mm or more and 5 mm or less are most preferable. By setting the film thickness within this range, the diffusion rate of the impurity metal eluted from the metal container and / or the tube can be suppressed more effectively, and the contamination of the sponge titanium by the impurity metal can be further reduced. it can.

More specifically, the metal container and tube include a metal container for storing molten metal magnesium, a metal container for transferring molten metal magnesium, and titanium tetrachloride in the reduction step. A metal reaction vessel that reacts with metallic magnesium, a metallic container for recovering metallic magnesium or magnesium chloride or a mixture thereof in a vacuum separation step, and then heating the recovered metallic magnesium and magnesium chloride to bring them into a molten state. Alternatively, it refers to a molten magnesium, a molten magnesium chloride, or a metal tube in contact with a mixture of two or more of these in a method for producing titanium sponge.

The metal container and / or tube in the method for producing titanium sponge of the present invention is at least a part of a portion in contact with molten metallic magnesium, molten magnesium chloride or produced titanium sponge, or a mixture of two or more thereof. The metal container and / or tube may have a titanium film on the entire surface of contact with molten magnesium, molten magnesium chloride or produced titanium sponge, or a mixture of two or more thereof. It is preferable to have a titanium film, and it is more preferable to have a titanium film on the entire inner wall of the metal container and / or tube.

The titanium film is particularly a metal reaction vessel for reacting titanium tetrachloride with molten metallic magnesium, and the metallic magnesium recovered after recovering metallic magnesium, magnesium chloride or a mixture thereof in a vacuum separation step. And magnesium chloride are preferably formed on at least a part of the inner wall of the metal container for heating and melting. If it is a metal reaction vessel, it can be applied to at least a part of molten metal magnesium, molten magnesium chloride or titanium sponge produced, or a mixture of two or more of these. preferable. Further, in the case of a metal container for storing or transferring metallic magnesium, it is preferable to form the titanium film at least a part of the height up to the height at which the molten magnesium comes into direct contact. Further, in the case of a metal tube, it is preferable to form the titanium film on at least a part of a portion that may come into contact with the molten metal when it flows.

The metal container and / or tube of the present invention is preferably made of stainless steel or low carbon steel so as to withstand the reaction at high temperature where the reduction reaction of molten metallic magnesium and titanium tetrachloride occurs. Is used.

The titanium film in the method for producing titanium sponge of the present invention is, for example, a titanium powder, a paste containing titanium hydride powder or both (that is, titanium powder paste, titanium hydride powder paste, or titanium powder and titanium hydride powder. It can be formed by preparing a mixed powder paste), applying the prepared paste to at least a part of the inner wall of a metal container and / or a tube, and then heat-treating.

As one embodiment of the method for producing titanium sponge in the present invention using the above paste, for example, a paste containing titanium powder, titanium hydride powder, or both is applied to the inner wall of a metal container and / or a pipe, and then By heat treatment, at least a part of the metal container and / or the inner wall of the pipe in contact with molten metallic magnesium, molten magnesium chloride or produced titanium sponge, or a mixture of two or more thereof is titanium. Examples thereof include a method in which a film is formed and sponge titanium is produced by a reduction reaction between titanium tetrachloride and metallic magnesium using a metal container and / or a tube on which the titanium film is formed.

Hereinafter, a preferable example of forming a titanium film by the titanium powder paste will be described. Even when the hydrogenated titanium powder paste or the mixed powder paste of titanium powder and hydrogenated titanium powder is used, the following preferable aspects or ranges can be applied as in the case of using the titanium powder paste. ..

The titanium powder paste that can be used for forming the titanium film of the present invention is preferably a paste composed of an organic component containing titanium powder and a binder resin.

The average particle size of the titanium powder used in the titanium powder paste is 1 μm or more and 500 μm or less from the viewpoint of forming a titanium film having high adhesion to the inner wall and preventing the elution of impurity metals due to partial peeling of the titanium film. Is preferable, 1 μm or more and 200 μm or less are more preferable, 1 μm or more and 50 μm or less are further preferable, and 1 μm or more and 25 μm or less are even more preferable. Since titanium powder has a risk of ignition, the lower limit of the average particle size may be 15 μm or more.
The average particle size of the titanium powder can be measured by a laser diffraction / scattering type particle size distribution measuring device. Specifically, after ultrasonically dispersing titanium powder at an output of 30 W for 4 minutes, a laser diffraction / scattering particle size distribution measuring device is used using pure water as a dispersion medium and sodium hexametaphosphate as a dispersant. Let D50 measured by (LA-920, manufactured by HORIBA, Ltd.) be the average particle size of the titanium powder.

As the titanium powder to be used, known titanium powder can be used. Examples of known titanium powder include HDH powder produced by the HDH method (hydrogenation dehydrogenation method), atomization powder produced by the gas atomization method, titanium powder produced by the PREP method (plasma rotating electrode method), and the like. Be done. The binder resin is preferably one that oxidizes and / or decomposes and / or vaporizes during heat treatment. For example, polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl butyral, aqueous cellulose (methylcellulose, 2-methacryloyloxyethyl phosphorylcholine, hydroxypropylmethylcellulose, etc.), aqueous cellulose, etc. Examples include acrylic (emulsion, etc.), polyethylene oxide, ethyl cellulose, nitrocellulose, and the like.

The titanium film of the present invention can be formed by adding water, an organic solvent, or the like to titanium powder to prepare a titanium powder paste and heat-treating it, if necessary. As the organic solvent for preparing the titanium powder paste, it is preferable to use one prepared by mixing water so that the ratio of water to the organic solvent is 1: 10 to 1: 1000.

Further, in order to improve the dispersibility of the titanium powder, a dispersant may be added as needed. For example, SN Dispersant 5040 (manufactured by Sampunoco Co., Ltd.) and the like can be mentioned. The amount of the dispersant added is preferably about 0.1% by mass with respect to the total amount of the titanium powder, the binder and the solvent.

As a method for producing a titanium powder paste, for example, the titanium powder, a binder resin, and an organic component containing a solvent, a dispersant, and other agents (plasticizer, thixo agent, foam disinfectant, etc.), if necessary, are kneaded. , The method of dispersion can be mentioned. The dispersion method for kneading is not particularly limited. When a disperser is used, for example, a three-roll mill, a ball mill, a bead mill, a roller mill, a planetary mixer, a clear mix, or the like can be used.

The heat treatment of the titanium powder paste applied to the inner wall of the metal container and / or the tube is preferably performed at 100 ° C. or higher and 1080 ° C. or lower in a vacuum or in an inert gas atmosphere (argon gas atmosphere, nitrogen gas atmosphere, etc.). Preferably, it is carried out at 700 ° C. or higher and 1080 ° C. or lower. The reason for performing the heat treatment in this temperature range is that the eutectic melting temperature of iron and titanium is 1080 ° C., and if the heat treatment is performed at a temperature exceeding 1080 ° C., there is a risk of melting the container wall surface. However, for a short time, the surface of the inner wall of the container can be temporarily melted and the titanium powder and the inner wall of the container can be baked and hardened. Therefore, the temperature and time must be appropriately combined.
The titanium powder paste applied to the inner wall of the metal container and / or the pipe may be demineralized before the heat treatment. Demetrization means that most of the organic solvent and water are volatilized and removed from the titanium paste by heating. For example, it is preferable to remove the medium while flowing dry air at 100 ° C. or higher and 300 ° C. or lower for 1 to 3 hours because deterioration of the vacuum pump used during vacuum heating can be prevented.

The sponge titanium obtained by the method for producing sponge titanium of the present invention is a sponge titanium having a significantly reduced concentration of impurity metals as compared with general sponge titanium. In particular, it is possible to obtain titanium sponge having 2 ppm or less of iron in the center of titanium sponge (50 mm inside from the surface) and 1 ppm or less of nickel and chromium, respectively.

Further, as the method for producing a processed titanium product or a cast product of the present invention, sponge titanium produced by the method of the present invention is used. Since the sponge titanium obtained by the production method of the present invention has high purity, it is suitable as a raw material for various processed titanium products or cast products. For example, examples of titanium castings include ingots, billets, and slabs, and examples of titanium processed products include titanium plates, titanium strips, titanium tubes, titanium rods, titanium wires, and titanium target materials.

The metal container and / or tube of the present invention is a metal container or tube used for producing sponge titanium by a reduction reaction between titanium tetrachloride and metallic magnesium, and has a titanium film on at least a part of an inner wall. In particular, it is preferably a molten metal magnesium, a molten magnesium chloride or a produced sponge titanium, or a metal container and / or a tube in contact with a mixture of two or more thereof, and a molten metal that becomes a high temperature state. More preferably, it is a metal container and / or tube that comes into contact with magnesium or magnesium chloride in a molten state or a mixture thereof.

Hereinafter, the contents of the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

(1) Raw material for titanium powder paste and method for producing titanium powder paste 1) Titanium powder: HDH powder (average particle size 20 μm), HDH powder (average particle size 45 μm), HDH powder (average particle size 150 μm)
2) Organic solvent: Polyvinyl alcohol 3) Dispersant: SN Dispersant (manufactured by San Nopco Co., Ltd.)

(Organic solvent): (water) = 1: 100 was blended to prepare a mixed solvent, and a dispersant was added in an amount of 0.2% by mass with respect to the mixed solvent to prepare a solvent. Then, the titanium powder and the solvent were mixed so as to have a ratio of (titanium powder): (solvent) = 30 kg: 9 kg to produce a titanium powder paste.

(2) Titanium film forming method The titanium powder paste obtained in (1) above is applied to the inner wall of a reaction vessel made of low carbon steel or SUS316 to form a titanium powder paste film, and then under the following conditions. The medium was removed and heat treatment was performed to form a titanium film on the inner wall of the reaction vessel.

1) Demediation conditions Temperature: 100 ° C
Dry air ventilation time: 3 hours 2) Heat treatment conditions Temperature: 800 ° C
Time: 3 hours Atmosphere: Vacuum

(3) Method for measuring the thickness of the titanium film The method for measuring the thickness of the titanium film is, for example, as shown in FIG. 1, when the titanium layer 3 is formed on the inner wall 1 of the reaction vessel, the inner wall of the reaction vessel is measured. The thickness of only the titanium film 3 in the outer portion of the alloy layer 2 of the material and titanium is measured as follows. A part of the titanium film formed on the inner wall of the reaction vessel is cut out and cut into about 1 cm × 1 cm × 1 cm square with a slicing machine, and about 20 g of cold embedded resin (main component polyester resin) and a curing agent (hardener) Embed in a molding mold using about 2 g of methyl ethyl ketone peroxide (methyl ethyl ketone) and leave it for about 1 day to harden the resin and use it as a sample. Then, polishing is performed using water-resistant abrasive paper so that the cross section of the sample comes out of the resin layer, and the surface of the sample to be measured is platinum-coated with a vacuum vapor deposition machine. For the sample thus obtained, the thickness of the layer corresponding to the titanium film was measured at 10 points using an electron probe microanalyzer (SUPERPROBE JXA-8100, manufactured by JEOL Ltd.), and the minimum value among them was measured. Was the thickness of the titanium film.

(4) Method for measuring the relative elution rate of impurity metals from the inner wall of the reaction vessel In the reaction vessel obtained in (2) above, 10 tons of metallic magnesium having a purity of 99.9% was added, and then in an argon atmosphere. It was heated for 3 hours, held at 900 ° C. for 3 hours, and cooled. The obtained metallic magnesium is sampled, and the concentration of impurity metals (iron, nickel, chromium) in the sample is measured by an ICP emission spectroscopic analyzer (SPS3100 (24H), manufactured by Hitachi High-Tech Science Co., Ltd.) to obtain a titanium film. Using Comparative Example 1 (or Comparative Example 4) in which no film was formed as a reference (= 1), the relative concentration of the impurity metal eluted from the reaction vessel into the metallic magnesium was determined, and this was used as the relative dissolution rate of the impurity metal. ..

(5) Method for measuring iron concentration in the center of sponge titanium The iron concentration in the center of sponge titanium is determined by a columnar mass of sponge titanium (diameter) extracted from the reaction vessel after a reduction reaction step and a subsequent vacuum separation step. The average iron concentration in the inner part from the depth of 50 mm from the outer peripheral surface of about 2 m and the height of about 2 m) was measured by ICP-MS (SPQ9700, manufactured by Hitachi High-Tech Science Co., Ltd.).

[Example 1]
A reaction vessel (made of low carbon steel, diameter: about 2 m, height: about) using a titanium powder paste using HDH powder (average particle size 20 μm) as the titanium powder and having a titanium film with a thickness of 0.6 mm on the entire inner wall. 4 m) was prepared. Using this, the relative elution rate of iron from the reaction vessel to metallic magnesium was determined. The results are shown in Table 1.

[Example 2]
The relative elution rate of iron from the reaction vessel to the metallic magnesium was determined under the same conditions as in Example 1 except that the thickness of the titanium film was changed from 0.6 mm to 0.02 mm. The results are shown in Table 1.

[Example 3]
The relative elution rate of iron from the reaction vessel to the metallic magnesium was determined under the same conditions as in Example 1 except that the film thickness of the titanium film was changed from 0.6 mm to 1 mm. The results are shown in Table 1.

[Example 4]
The relative elution rate of iron from the reaction vessel to the metallic magnesium was determined under the same conditions as in Example 1 except that the film thickness of the titanium film was changed from 0.6 mm to 3 mm. The results are shown in Table 1.

[Example 5]
The relative elution rate of iron from the reaction vessel to metallic magnesium was determined under the same conditions as in Example 1 except that the titanium powder was changed from HDH powder (average particle size 20 μm) to HDH powder (average particle size 45 μm). It was. The results are shown in Table 1.

[Example 6]
The relative elution rate of iron from the reaction vessel to metallic magnesium was determined under the same conditions as in Example 1 except that the titanium powder was changed from HDH powder (average particle size 20 μm) to HDH powder (average particle size 150 μm). It was. The results are shown in Table 1.

[Comparative Example 1]
The elution concentration of iron from the reaction vessel to metallic magnesium was determined under the same conditions as in Example 1 except that a reaction vessel without a titanium film (made of low carbon steel, diameter: about 2 m, height: about 4 m) was used. This was used as a reference (= 1) for Examples 1 to 6 and Comparative Examples 2 to 3.

[Comparative Example 2]
Using a container made of low carbon steel (diameter: about 2 m, height: about 4 m) and crushed particles of titanium sponge (raw material for film formation) (average particle size: 50 mm to 150 mm, porosity 30 to 50%), The heat treatment was performed under the following conditions as described in Example 1 of 2009-127107, and titanium was vapor-deposited on the entire inner wall of the reaction vessel to form an alloy layer of the material of the inner wall of the reaction vessel and titanium. The relative elution rate of iron from the reaction vessel to metallic magnesium was determined under the same conditions as in Example 1 except that this vessel was used instead of the reaction vessel having a titanium film thickness of 0.6 mm. The results are shown in Table 1.

Heat treatment conditions Temperature: 1000 ° C
Vacuum degree: 10 to 50 Pa
Time: 40 hours

[Comparative Example 3]
Using a container made of low carbon steel (diameter: about 2 m, height: about 4 m) and crushed particles of high chlorine sponge titanium (average particle size: 12.5 mm), as shown in Example 2 of JP-A-2014-214356. As was done, an alloy layer was formed at the contact portion between titanium and the material of the inner wall of the reaction vessel. Specifically, crushed particles of high chlorine sponge titanium were loaded into an unused reaction vessel and heat-treated under the following conditions. The relative elution rate of iron from the reaction vessel to metallic magnesium was determined under the same conditions as in Example 1 except that this vessel was used instead of the reaction vessel having a titanium film thickness of 0.6 mm. The results are shown in Table 1.

Heat treatment conditions Temperature: 800 ° C to 1080 ° C
Time: 100 hours

[Example 7]
A reaction vessel made of SUS316 (diameter: about 2 m, height: about 4 m) was used instead of the reaction vessel made of low carbon steel, and a titanium film having a thickness of 0.6 mm was applied to the entire inner wall in the same manner as in Example 1. The relative elution rate of the impurity metal (iron, nickel, chromium) from the reaction vessel to the metallic magnesium was determined under the same conditions as in Example 1 except that the above was formed. The results are shown in Table 2.

[Comparative Example 4]
Under the same conditions as in Example 1 except that a reaction vessel made of SUS316 (diameter: about 2 m, height: about 4 m) was used instead of the reaction vessel made of low carbon steel, and a titanium film was not formed. , The elution concentration of the impurity metal (iron, nickel, chromium) from the reaction vessel to the metallic magnesium was determined, and this was used as the standard (= 1) for Example 7.

[Example 8]
A titanium film having a thickness of 0.6 mm was formed on the entire inner wall of the reaction vessel (made of SUS316, diameter: about 2 m, height: about 4 m) by the same method as in Example 1. Using this reaction vessel, titanium sponge was produced by the method described in Non-Patent Document 1, and the iron concentration at the center of the titanium sponge was measured. The results are shown in Table 3.

[Example 9]
In addition to the entire inner wall of the reaction vessel used in Example 8, the thickness of the entire inner wall of the following container for transferring molten metallic magnesium and the following container for storing molten metallic magnesium in the same manner as in Example 1 A 0.6 mm titanium film was formed. Using this container, sponge titanium was produced by the method described in Non-Patent Document 1, and the iron concentration at the center of the sponge titanium was measured. The results are shown in Table 3.

Storage container for molten magnesium: Low carbon steel Diameter: Approx. 1.5 m, Height: Approx. 2 m
Transfer container for molten magnesium: Low carbon steel Diameter: Approx. 1.5 m, Height: Approx. 1.5 m

[Comparative Example 5]
As shown in Example 2 of JP-A-2014-214356, an alloy layer is formed at the contact portion between titanium and the material of the inner wall of the reaction vessel (made of SUS316, diameter: about 2 m, height: about 4 m). It was. Using this reaction vessel having an alloy layer, titanium sponge was produced by the method described in Non-Patent Document 1, and the iron concentration at the center of the titanium sponge was measured. The results are shown in Table 3.

The method for producing a metal container or tube and sponge titanium of the present invention can prevent contamination by impurities from the metal container and / or tube, and thus enables the production of high-purity titanium sponge. The high-purity titanium sponge produced by the present invention can be suitably used as a raw material for various processed titanium products or cast products.

1 Inner wall of the reaction vessel 2 Alloy layer of metal and titanium on the inner wall of the reaction vessel 3 Titanium film

Claims (2)

A method for producing sponge titanium by a reduction reaction between titanium tetrachloride and metallic magnesium, at least of a portion in contact with molten metallic magnesium, molten magnesium chloride or produced sponge titanium, or a mixture of two or more thereof. some, average particle size 1μm or 200μm or less titanium powder, the average particle diameter of 1μm or 200μm or less titanium hydride powder or paste containing both applied to the inner wall of the metal container and / or the tube, 700 ° C. or higher A method for producing titanium sponge, using a metal container and / or a tube having a titanium film formed by heat treatment at 1080 ° C. or lower . The method for producing titanium sponge according to claim 1 , wherein the thickness of the titanium film is 0.02 mm or more.

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