JP6908412B2 - Manufacturing method of titanium sponge - Google Patents

Description

The present invention relates to a method for producing high-purity titanium sponge, which is produced by reducing titanium tetrachloride with metallic magnesium to produce titanium sponge.

Conventionally, metallic titanium is industrially manufactured based on sponge titanium manufactured by the Kroll process. In recent years, the demand for high-purity titanium for semiconductor devices has been increasing, and along with this, there is a demand for inexpensive production of high-purity titanium sponge.

The titanium sponge titanium production process by this Kroll process is roughly divided into four steps: a chloride distillation step, a reduction separation step, a crushing step and an electrolysis step.

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 metal magnesium in a stainless steel reduction reaction vessel to cause a reduction reaction to produce titanium sponge. Next, in the vacuum separation step, the titanium sponge produced in the reduction step is evacuated at a high temperature and under reduced pressure to produce titanium sponge from which residual magnesium chloride and metallic magnesium have been removed (Non-Patent Document 1). ..

The titanium sponge after vacuum separation is extruded by a punching floor member installed at the bottom of the container called a rostrum or a punching punch. In addition, it was thought that the titanium sponge that adhered to the rostrum after extraction and the surface of the reduction reaction vessel and remained contained a large amount of impurity metals. Therefore, by physically removing titanium-based impurities (hereinafter referred to as "adhered titanium") adhering to the inner surface of the reduction reaction vessel and the surface of the rostrum by chipping called chipping removal, the following is performed. It was thought that the purity of titanium sponge produced in the batch was improved (Patent Document 1).

From this, it is considered that the more the adhered titanium on the inner surface of the reduction reaction vessel is scraped, the higher the purity is considered, and it is preferable to remove the adhered titanium so that the background is exposed over a wide area in the reduction reaction vessel. And, although these chipping removal operations significantly deteriorated productivity, they were considered to be unavoidable.

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

JP 2006-265587 JP 2006-131976

The present invention solves the above-mentioned problems concerning the production of high-purity titanium sponge, and an object of the present invention is to provide a method for producing titanium sponge, which can reduce the load of the work of removing the shavings in the reduction reaction vessel.

In order to solve the above problems, the present inventors have focused on the Ni contamination path in the adhered titanium adhering to the inner surface of the reduction reaction vessel after taking out the sponge titanium produced from the reduction reaction vessel, and diligently studied it. As a result of stacking, the mechanism by which Ni is concentrated in the adhered titanium is not the contamination due to the gettering effect on the initially produced titanium described in Patent Document 1, but the Ni in the raw material Mg and the inside of the reduction reaction vessel during the reduction reaction. It was found that the main factor was that the Ni eluted in the molten Mg did not evaporate in the vacuum separation step after the completion of the reduction reaction, and the remaining Ni in the Mg was incorporated into the adhered titanium on the inner surface of the reduction reaction vessel. rice field.

The present invention has been made based on such findings, and is as follows.
That is, according to the present invention (1), in the production of titanium sponge by the Kroll process, after performing the shaving removal to remove the adhered titanium adhering to the inner surface of the reduction reaction vessel and the surface of the rostrum during the previous reduction reaction, the shaving is performed. A method for producing high-purity titanium sponge, which comprises a step of producing titanium sponge by the Kroll process by reusing the removed reduction reaction vessel.
In the removal of the suspension, the inner surface of the reduction reaction vessel and the rostrum which are present in the range of 50% from the bottom with respect to the total height of the reduction reaction vessel and in the range of 50% from the bottom with respect to the total height of the reduction reaction vessel. The ratio (average exposure rate A) of the total area of the inner surface of the reduction reaction vessel and the surface of the rostrum whose skin is exposed after the removal of the suspension to the total area of the surface is 50% or more, and in the range excluding the range of 50% below the total height of the reduction reaction vessel, said the and scalp of exposure rate B of the surface of the inner surface of the reduction reaction vessel after the fishing removed, the chipping removed the difference between the exposure rate C of background of the surface of the inner surface of the reduction reaction vessel before carrying out (exposure rate B- exposure ratio C) is such that 20% or less, to perform the chipping removal of said adhesion titanium,
The present invention provides a method for producing high-purity titanium sponge, which is characterized by the above.

Further, the present invention (2) is characterized in that the melt outlet of the reduction reaction vessel is located in the range of 5 to 20% from the bottom with respect to the total height of the reduction reaction vessel (1). Provided is a method for producing high-purity titanium sponge.

According to the present invention, it is possible to provide a method for producing high-purity titanium sponge, which can reduce the load of chipping removal work in the reduction reaction vessel.

It is a schematic vertical end view which shows the reduction reaction apparatus used in the manufacturing method of high-purity sponge titanium of this invention. It is a vertical end view of the reduction reaction vessel for demonstrating the total height of the reduction reaction vessel.

In the method for producing high-purity titanium sponge of the present invention, in the production of titanium sponge by the Kroll process, the titanium adhering to the inner surface of the reduction reaction vessel and the surface of the rostrum during the previous reduction reaction was removed by hanging. After that, it is a method for producing high-purity titanium sponge, which comprises a step of producing titanium sponge by the Kroll process by reusing the reduction reaction vessel from which the suspension has been removed.
In the removal of the suspension, the inner surface of the reduction reaction vessel and the rostrum which are present in the range of 50% from the bottom with respect to the total height of the reduction reaction vessel and in the range of 50% from the bottom with respect to the total height of the reduction reaction vessel. The ratio (average exposure rate A) of the total area of the inner surface of the reduction reaction vessel and the surface of the rostrum whose skin is exposed after the removal of the suspension to the total area of the surface is 50% or more, and in the range excluding the range of 50% below the total height of the reduction reaction vessel, said the and scalp of exposure rate B of the surface of the inner surface of the reduction reaction vessel after the fishing removed, the chipping removed the difference between the exposure rate C of background of the surface of the inner surface of the reduction reaction vessel before carrying out (exposure rate B- exposure ratio C) is such that 20% or less, to perform the chipping removal of said adhesion titanium,
This is a method for producing high-purity titanium sponge, which is characterized by the above.

The method for producing high-purity titanium sponge of the present invention is a Kroll process, that is, by putting molten Mg in a reduction reaction vessel in advance and dropping titanium tetrachloride into the reduction reaction vessel to react with the molten Mg. This is a method for producing high-purity titanium sponge for producing titanium sponge.

Then, in the method for producing high-purity titanium sponge of the present invention, the adhered titanium adhered to the inner surface of the reduction reaction vessel and the surface of the rostrum during the previous reduction reaction is scraped off, so that the adhered titanium is removed from the inner surface of the reduction reaction vessel and the rostrum. A method for producing high-purity titanium sponge, which comprises a step of producing titanium sponge by a Kroll process by removing it from the surface of the titanium, that is, by reusing the reduction reaction vessel from which the titanium has been removed. Is.

In the present invention, the high-purity titanium sponge refers to titanium sponge having a Ni content of 0.5 mass ppm or less.

The reduction reaction vessel according to the method for producing high-purity sponge titanium of the present invention is a clad vessel or buttering vessel in which iron is clad on the inner surface of stainless steel, and the rostrum is made of iron.

The structure of the reduction reaction vessel according to the method for producing high-purity titanium sponge of the present invention will be described with reference to FIG. FIG. 1 is a schematic end view showing a reduction reaction apparatus used in the method for producing high-purity titanium sponge of the present invention. The reduction reaction apparatus 1 includes a reduction reaction vessel 2, an eluate extraction tube 4 connected to the lower part of the reduction reaction vessel 2, and an inner lid 6 and an outer lid 5 that close the upper side of the reduction reaction vessel 2. The bottom of the reduction reaction vessel 2 is closed with a bottom cap 8. A rostrum 3 is installed in the lower part of the reduction reaction vessel 2. Then, in the reduction step, the production of titanium sponge is carried out by putting molten Mg in the reduction reaction vessel 2 in advance, dropping titanium tetrachloride into the reduction reaction vessel 2 and reacting with the molten Mg. The produced titanium sponge is deposited on top of 3. In the reduction step, magnesium chloride produced as a by-product is extracted from the eluate extraction tube 4 while dropping titanium tetrachloride onto the molten Mg. After the dropping of titanium tetrachloride into the molten Mg is completed, the inside of the reduction reaction vessel 2 is vacuum-heated to perform a separation step of vacuum-separating the unreacted Mg and the by-product magnesium chloride. After performing the separation step, the titanium sponge mass produced together with the reduction reaction vessel is cooled, the bottom cap 8, the inner lid 6 and the outer lid 5 are removed, and the titanium sponge mass is pushed up together with the rostrum 3 from below to remove the titanium sponge mass. , Take out from the reduction reaction vessel 2.

Next, in order to reuse the reduction reaction vessel 2 for the next reduction reaction, the titanium adhered to the inner surface of the reduction reaction vessel 2 and the surface of the rostrum 3 after the titanium sponge mass is taken out is removed by fishing. .. In the chipping removal, when the position 14 which is 50% higher than the total height 13 of the reduction reaction vessel 2 is set as the upper end of the 50% range, it exists in the portion 15 below the upper end 14 of the 50% range. Chipping is removed centering on the adhered titanium on the inner surface of the reduction reaction vessel 2 and the surface of the rostrum 3, and if necessary, the inner surface of the reduction reaction vessel 2 in the range 16 above the upper end 14 in the 50% range is removed from the chipping. conduct. In the case of the reduction reaction vessel 2, the bottom surface 9 and the side surface 10 of the bottom cap 8 are also within the range of 50% from the bottom, and after the chipping is removed, the bottom cap 8 is again attached to the bottom of the reduction reaction vessel 2. The bottom surface 9 and the side surface 10 of the bottom cap 8 are subject to chipping removal.

Then, the reduction reaction vessel 2 after the chipping removal is reused for the next reduction reaction.

In the present invention, the "total height of the reduction reaction vessel" means the deepest position inside the reduction reaction vessel with which the molten Mg comes into contact when the reduction reaction vessel is viewed in the vertical direction. , Refers to the length to the upper end position of the inner surface of the reduction reaction vessel. When the reduction reaction vessel does not have a bottom cap as in the embodiment shown in FIG. 2 (A), the deepest position at the bottom of the reduction reaction vessel is the deepest position inside the reduction reaction vessel, and When the reduction reaction vessel has a bottom cap as in the morphological examples shown in FIGS. 2B to 2D, the deepest position of the bottom cap is the deepest position inside the reduction reaction vessel. In each of the morphological examples (A) to (D) shown in FIG. 2, the position indicated by reference numeral 11 is the deepest position inside the reduction reaction vessel with which the molten Mg is in contact, and the position indicated by reference numeral 12 is the position indicated by reference numeral 12. The upper end position of the inner surface of the reduction reaction vessel, and the distance from the position indicated by reference numeral 11 to the position indicated by reference numeral 12 is the total height 13 of the reduction reaction vessel. Further, in the present invention, "the range of 50% from the bottom with respect to the total height of the reduction reaction vessel" is a position higher than the deepest position inside the reduction reaction vessel by 50% of the total height inside the reduction reaction vessel. Refers to the portion below the position of the upper end of the 50% range, where is defined as the upper end of the 50% range.

In the method for producing high-purity titanium sponge of the present invention, the method for removing the shavings is not particularly limited, and any method that is used in the ordinary production of titanium sponge may be used. For example, the adhered titanium is hit by a chipping machine. There are a method of scraping while scraping, a method of removing with a scraper or a wire brush, and the like. The method using a chipping machine is suitable for removing the adhered titanium firmly adhering to the inner surface of the reduction reaction vessel and the surface of the rostrum, and the method using a scraper or a wire brush is suitable for removing the adhering titanium. It is suitable for removing adhered titanium, which has weak adhesion to the inner surface of the container and the surface of the rostrum.

In the chipping removal according to the method for producing high-purity sponge titanium of the present invention, the reduction existing in the range of 50% from the bottom with respect to the total height of the reduction reaction vessel and in the range of 50% from the bottom with respect to the total height of the reduction reaction vessel. The ratio of the total area of the inner surface of the reduction reaction vessel and the surface of the rostrum to which the background is exposed after the chipping removal is the ratio of the total area of the inner surface of the reaction vessel and the surface of the rostrum (also referred to as average exposure rate A). , 50% or more, preferably 70% or more, particularly preferably 90% or more, and the attached titanium is chipped off. In the method for producing high-purity titanium sponge of the present invention, in the chipping removal, the adhered titanium is chipped and concentrated in the lower part of the reduction reaction vessel so that the average exposure rate A after chipping removal is within the above range. Since the attached titanium having a high Ni content is removed from the inner surface of the reduction reaction vessel and the surface of the rostrum, the load of the chipping removal work can be reduced, and the sponge produced in the next batch can be reduced. Ni contamination of titanium can be efficiently reduced.

Further, by repeatedly reusing the reduction reaction vessel and rostrum, the inner surface of the reduction reaction vessel and the surface of rostrum are partially reacted with titanium sponge and alloyed. Is the iron surface of the inner surface of the original reduction reaction vessel and the iron surface of the surface of the rostrum, or the titanium iron on the inner surface of the reduction reaction vessel where the average Ti concentration from the surface layer to 300 μm is 30% by mass or less in the surface analysis by EPMA. Refers to the titanium-iron alloy surface on the alloy surface and the surface of the rostrum.

In the present invention, "the background is exposed" means that there is no adhesion of adhered titanium, and the original iron surface of the inner surface of the reduction reaction vessel or the surface of the rostrum or the alloyed titanium iron alloy surface is visually confirmed. Refers to that.

In the present invention, the method for measuring the total area of the inner surface of the reduction reaction vessel with the exposed background and the surface of the rostrum is the method of measuring the total area. Take pictures of the inner surface of a reduction reaction vessel and the surface of the rostrum. At this time, the imaging range of one field of view is about 300 mm × 400 mm, the number of pixels is 1600 × 1200 pixels or more, and the inner surface of the reduction reaction vessel and the surface of the rostrum within the range of 50% from the bottom with respect to the total height of the reduction reaction vessel. Shoot over the entire range. Next, each of the obtained photographs is binarized using an image processing analysis device (manufactured by Luzex AP NIRECO), and then a portion where the background is exposed is selected and the area ratio is measured. The area ratio is obtained by the formula of "(X / (X + Y)) x 100", where X is the area of the portion where the background is exposed and Y is the area of the other portion. The area ratio of each of the obtained photographs was measured by the above method, and the average value of the area ratios of all the photographs was present in the range of the average exposure rate A (%) (50% from the bottom with respect to the total height of the reduction reaction vessel). The ratio of the total area of the inner surface of the reduction reaction vessel and the surface of the rostrum to which the skin is exposed after the removal of the shavings is taken as the ratio of the total area of the inner surface of the reduction reaction vessel and the surface of the rostrum.

The high-purity sponge according to the manufacturing method of the titanium hanging removal of the present invention, in a range excluding the range of 50% below the total height of the reduction reaction vessel, chipping remove the inner surface of the reduction reaction vessel after a background exposure rate B (%), the difference between the exposure rate of the background of the surface of the inner surface of the front of the reduction reaction vessel to perform chipping removed C (%) (exposure rate B- exposure ratio C) is more than 20% The attached titanium is chipped off so as to be preferably 10% or less, particularly preferably 0%. In the method for producing high-purity sponge titanium of the present invention, in the chipping removal, the difference in the exposure rate before and after the chipping removal (exposure rate B-exposure rate C) is within the above range, so that the load of the chipping removal work is reduced. be able to. The total height of the reduction reaction vessel is less than that of the titanium sponge above the range of 50% from the bottom with respect to the total height of the reduction reaction vessel. Even if the adhered titanium adhering to the range excluding the range of 50% from the bottom is used in the next batch while remaining in the reduction reaction vessel, it affects the yield of high-purity sponge titanium. do not have. Then, the load of the chipping removal work can be reduced by reducing the amount of chipping of the adhered titanium in the range excluding the range of 50% from the bottom with respect to the total height of the reduction reaction vessel. Further, since the adhered titanium is kept in contact with the iron on the surface of the reduction reaction vessel and kept at a high temperature of 1000 ° C. or higher for a long time in the vacuum separation step, the adhered titanium and the iron surface on the inner surface of the reduction reaction vessel form an alloy layer. However, the adhesion is very strong. When the sponge mass is pushed out from the reduction reaction vessel, a part of the adhered titanium forming the titanium-iron alloy layer is peeled off, and at that time, a part of the titanium-iron alloy layer and the base material is together with the adhered titanium. It may come off and the inner surface of the container may be consumed. It is preferable to exceptionally remove the adhered titanium having a thickness of more than about 20 mm, which interferes with the pushing out of the titanium sponge mass in the next reduction reaction.

In the present invention, is a method of calculating the "exposure factor C", before chipping removal, a photograph of the surface of the inner surface of the reduction reaction vessel at the top than the range of 50% below the total height of the reduction reaction vessel Take a picture. In this case, the shooting range of one field of view about 300 mm × 400 mm, the number of pixels and 1600 × 1200 pixels or more, the total of the inner surface of the reduction reaction vessel at the top than the range of 50% below the total height of the reduction reaction vessel Shoot over a range. Next, each of the obtained photographs is binarized using an image processing analysis device (manufactured by Luzex AP NIRECO), and then a portion where the background is exposed is selected and the area ratio is measured. The area ratio is obtained by the formula of "(X / (X + Y)) x 100", where X is the area of the portion where the background is exposed and Y is the area of the other portion. The area ratio of each of the obtained photographs was measured by the above method, and the average value of the area ratios of all the photographs was set to the exposure rate C (%) (above the range of 50% from the bottom with respect to the total height of the reduction reaction vessel). with respect to the surface the product of the inner surface of a reduction reaction vessel, the background is the ratio) of the surface product of the inner surface of the reduction reaction vessel which is exposed before performing the chipping removed.

Further, in the present invention is a method of calculating the "exposure factor B", after chipping removal, a photograph of the inner surface of the reduction reaction vessel at the top than the range of 50% below the total height of the reduction reaction vessel shooting do. In this case, the shooting range of one field of view about 300 mm × 400 mm, the number of pixels and 1600 × 1200 pixels or more, the total of the inner surface of the reduction reaction vessel at the top than the range of 50% below the total height of the reduction reaction vessel Shoot over a range. Next, each of the obtained photographs is binarized using an image processing analysis device (manufactured by Luzex AP NIRECO), and then a portion where the background is exposed is selected and the area ratio is measured. The area ratio is obtained by the formula of "(X / (X + Y)) x 100", where X is the area of the portion where the background is exposed and Y is the area of the other portion. The area ratio of each of the obtained photographs was measured by the above method, and the average value of the area ratios of all the photographs was set to the exposure rate B (%) (above the range of 50% from the bottom with respect to the total height of the reduction reaction vessel). with respect to the surface the product of the inner surface of a reduction reaction vessel, the background is the ratio) of the surface product of the inner surface of the reduction reaction vessel which is exposed after removal chipping.

In the method for producing high-purity titanium sponge of the present invention, it is below the outlet that the melt outlet of the reduction reaction vessel is located in the range of 5 to 20% from the bottom with respect to the total height of the reduction reaction vessel. It is preferable in that the amount of the melt remaining in the melt can be reduced or the possibility of clogging of the melt outlet can be reduced.

In the method for producing high-purity titanium sponge of the present invention, using the same reduction reaction vessel, the inner surface of the reduction reaction vessel is thinned, Ni elution occurs from the SUS side of the clad steel, and it becomes unusable. , Repeatedly.

Hereinafter, the present invention will be described in more detail with reference to examples, but this is merely an example and does not limit the present invention.

(Examples 1 to 4 and Comparative Examples 1 to 2)
After performing the reduction reaction under the following conditions for producing titanium sponge, the produced titanium sponge mass was extracted, and the reduction reaction vessel after cooling was removed by chipping so as to have the exposure rate shown in Table 1. went. At that time, the load of the chipping removal work and the yield of high-purity titanium sponge when sponge titanium was produced using the reduction reaction vessel were determined.

<Manufacturing conditions for titanium sponge>
Weight of titanium sponge after vacuum separation: Approximately 7 tons
Inner diameter of reaction vessel: φ1900 mm
Amount of raw material Mg charged: 12000 kg
Extraction amount of magnesium and magnesium chloride after completion of reduction reaction: 9500 kg
Temperature of the outer surface of the reaction vessel during vacuum separation: 1000-1050 ° C
Vacuum separation time: 130 hours

<Calculation method of yield of high-purity titanium sponge>
Sponge titanium was produced using the reduction reaction vessel and rostrum after removing the shavings, and the ratio of the amount of sponge titanium collected with a Ni content of 0.5% by mass or less to the collected sponge titanium among the produced sponge titanium. Was determined as the yield of high-purity titanium sponge. When the height of the sponge mass after removal is H and the diameter is D, the upper surface of the sponge mass is 0.1H from the upper end, and the lower surface is 0.1H from the lower end. The lower part from the position corresponding to the above, and the outer part from the position corresponding to 0.1D in the radial direction from the outer surface of the outer circumference were cut and removed, and the remaining part was defined as the collected sponge titanium part. The results are shown in Table 1. In Table 1, the relative ratio is also shown with the yield of high-purity titanium sponge of Comparative Example 1 as 1.
In the method of collecting sponge titanium having a Ni content of 0.5 mass ppm or less, the collected sponge titanium portion collected by the above method is divided into about 30 kg units, the Ni content of each is analyzed, and the Ni content is contained. A section having an amount of 0.5 mass ppm or less was collected as high-purity titanium sponge.

<Calculation method of chipping removal workload>
The actual working time of the chipping removal work was defined as the time required for the chipping removal work. For example, when the chipping removal work was performed over a plurality of times, only the time during which the chipping removal work was actually performed was totaled. Table 1 shows the relative ratio, where 1 is the time required for the chipping removal work of Comparative Example 1.

Claims (2)

In the production of titanium sponge by the Kroll process, the reduction reaction vessel in which the shavings were removed after the shavings were removed to remove the adhered titanium adhering to the inner surface of the reduction reaction vessel and the surface of the rostrum during the previous reduction reaction. A method for producing high-purity titanium sponge having a Ni content of 0.5% by mass or less, which comprises a step of producing titanium sponge by the Kroll process by reusing.
In the removal of the suspension, the inner surface of the reduction reaction vessel and the rostrum which are present in the range of 50% from the bottom with respect to the total height of the reduction reaction vessel and in the range of 50% from the bottom with respect to the total height of the reduction reaction vessel. The ratio (average exposure rate A) of the total area of the inner surface of the reduction reaction vessel and the surface of the rostrum whose skin is exposed after the removal of the suspension to the total area of the surface is 50% or more, and In the range excluding the range of 50% from the bottom with respect to the total height of the reduction reaction vessel, the exposure rate B of the inner surface of the reduction reaction vessel after the removal of the suspension and the exposure rate B of the inner surface of the reduction reaction vessel before the removal of the suspension. The adhesive titanium is removed by shaving so that the difference (exposure rate B-exposure rate C) from the exposure rate C of the inner surface of the inner surface of the reduction reaction vessel is 20% or less.
When the height of the titanium sponge lump was H and the diameter was D, the upper surface of the titanium sponge lump was taken out after taking out the sponge titanium lump obtained by performing the step of producing the titanium sponge by the Kroll process. The upper part from the position corresponding to 0.1H or more from the upper end, the lower part from the position corresponding to 0.1H or more from the lower end for the lower surface, and 0.1D or more in the radial direction from the outer surface for the outer circumference. Collecting the remaining part after cutting and removing the outer part from the corresponding position,
A method for producing high-purity titanium sponge, which is characterized by. The method for producing high-purity titanium sponge according to claim 1, wherein the melt outlet of the reduction reaction vessel is located in the range of 5 to 20% from the bottom with respect to the total height of the reduction reaction vessel. ..

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