JP5796882B2 - Method for producing sponge titanium particles - Google Patents

Description

  The present invention relates to a method for producing ponzi titanium particles for producing granular sponge titanium from a sponge titanium mass produced by a crawl method.

  Conventionally, titanium metal is industrially produced from a sponge titanium mass produced by a crawl method. Sponge titanium particles for wrought material and sponge titanium particles for semiconductor devices are collected from this sponge titanium lump, and in any case, the collection is performed through the following steps.

  In the production of sponge titanium by the crawl method, the reduction reaction vessel is filled with molten Mg in advance. A titanium tetrachloride liquid is dripped there from the container upper part, and a sponge titanium lump is produced | generated by making it react with Mg in a container. When this reduction reaction step is completed, a sponge titanium lump is taken out from the reduction reaction vessel through a vacuum separation step and a cooling step.

  When the sponge titanium lump is taken out from the reduction reaction vessel, the lower part having a large amount of impurities is removed from the sponge titanium lump. Specifically, the worker removes the portion of the outer peripheral portion that is in contact with the inner surface of the container using a machine tool, for example, a small rock drill called a chipper. Further, even if the portion is not in contact with the inner surface of the container, the portion where the nitride is concentrated is removed by a machine tool, for example, a small rock drill called a chipper, while the operator visually observes the portion. Further, the lower part where impurities are concentrated by gettering in the initial stage of the reaction is cut and removed by a press blade. By the way, the sponge titanium lump is formed in a roughly cylindrical shape along the inner surface of the container, but precisely, it is formed in a deformed shape with a constriction due to the difference in reaction rate, etc. However, the outer peripheral surface of the middle step part is separated from the inner surface of the container by constriction, and the entire sponge titanium lump is formed in a shape like an hourglass compressed in the vertical direction.

  The titanium sponge lump from which the lower part has been removed is roughly divided by a press blade. The obtained sponge titanium piece (large piece) is divided by a multistage cutting machine. The obtained titanium sponge piece (small piece) is divided by a crusher such as a jaw crusher. Thus, granular sponge titanium is obtained. The obtained sponge titanium particles are packed in a container through a classification process.

  The above is the manufacturing process of sponge titanium particles for wrought material, but in the case of sponge titanium particles for semiconductor devices, only the central part with the least contamination in the sponge titanium lump is largely divided after the outer peripheral part is removed. It is collected at the stage. This process is called center sampling, center sampling, etc. (Patent Document 1). The collected central portion is divided into a large portion by a press blade, a middle portion by a multistage cutter, and a small portion by a crusher such as a jaw crusher. The part other than the center part is used as a wrought material.

  As the reduction reaction vessel, a stainless steel vessel having excellent heat resistance is usually used. However, in the stainless steel container, heavy metals such as Ni and Cr are eluted from the reduction reaction container into the molten Mg in the container, thereby contaminating the sponge titanium mass. For this reason, in recent operations, regardless of whether it is for wrought material or semiconductor devices, at least the inner surface of a clad container or a buttering container is used to prevent contamination caused by the container. However, as described above, the outer peripheral portion where Fe contamination from the inner surface of the container becomes a problem even when such a container is used, that is, the portion in contact with the inner surface of the container is to be removed.

  As described above, in the method of producing sponge titanium particles from the sponge titanium mass produced by the crawl method, it is indispensable to remove the lower part having a high impurity concentration in order to ensure the quality, and the yield reduction due to this becomes an inevitable problem. ing.

Japanese Patent Laid-Open No. 2008-190024

  An object of the present invention is to provide an economical method for producing titanium sponge particles capable of effectively suppressing a decrease in yield due to removal of a lower part having a high impurity concentration.

  In order to achieve the above object, the present inventor paid attention to the process of removing the lower part from the outer peripheral portion of the sponge titanium lump taken out from the reduction reaction vessel, particularly the handling of the lower part generated in the process. That is, of the outer peripheral portion of the sponge titanium lump taken out from the reduction reaction vessel, the portion that was in contact with the inner surface of the vessel was completely covered by an operator using a machine tool, for example, a small rock drill called a chipper. Remove. On the other hand, with respect to the portion that is not in contact with the inner surface of the container, the operator concentrates on the portion where the nitride is concentrated, and removes it partially with the machine tool or the like while visually observing the portion. The removal amount is overwhelmingly larger in the former.

  And, the lower part of the high Fe concentration with the overwhelmingly large removal amount has been treated uniformly, and the whole amount is disposed as a defective product, or the whole amount is pulverized and used as a Ti additive for steel It was used.

  Under such circumstances, in order to achieve the above object, the present inventor has reused the high-Fe lower portion removed from the outer peripheral portion of the sponge titanium lump removed in a relatively large amount, particularly from the portion in contact with the inner surface of the container. And conducted various surveys. As a result, it was found that the high Fe lower portion removed from the portion in contact with the inner surface of the container had a large quality difference depending on the size of the removed piece. That is, the operation of removing the lower portion from the outer peripheral portion of the sponge titanium lump is manually performed by the operator using the machine tool as described above. When the lower part is removed from the part that has been in contact with the inner surface of the container, the removal work is performed manually over the entire circumference of a considerably large area at the lower and upper parts of the sponge titanium lump. As a result, the size of the removal piece varies.

  Conventionally, removal pieces of various sizes have been treated uniformly, but it has been found that there is a large difference in impurity concentration between large and small removal pieces. That is, the high Fe lower removal piece removed from the portion in contact with the container inner surface basically has a contact surface with the container inner surface, and the impurity concentration in the vicinity of the contact surface is particularly high. When the size of the removal piece is different, the ratio of the highly contaminated area in the vicinity of the contact surface occupying the volume of the entire removed piece is different. The larger the removal piece, the smaller the ratio of the highly contaminated area and the higher the quality. That is, the larger the removed piece, the greater the tendency to be removed deeply from the outer peripheral surface of the lump, and the volume ratio of the highly contaminated area occupying the whole removed piece becomes smaller and the quality tends to increase.

  For this reason, if the high Fe lower removal pieces removed from the portion in contact with the inner surface of the container are classified with a specific particle size, those having a large particle size are classified as high quality materials among the high Fe lower removal pieces, and expanded. It became clear that it could be reused as a material for raw materials.

  The method for producing sponge titanium particles of the present invention has been completed on the basis of such knowledge, and the sponge titanium mass produced by the crawl method in a reduction reaction vessel and taken out from the reaction vessel is cut and crushed to obtain sponge titanium. When producing the grains, at least the lower part of the outer periphery of the sponge titanium block that was in contact with the inner surface of the reduction reaction container was removed, and the removed pieces removed from the lower part of the outer periphery of the sponge that were in contact with the inner surface of the reduction reaction container were classified. The feature of the structure is to separate the removal piece having a large particle size from the other removal pieces.

In the method for producing sponge titanium particles of the present invention, at least the lower part of the outer periphery of the titanium sponge block produced by the crawl method in the reduction reaction vessel and taken out from the reaction vessel is in contact with the inner surface of the reduction reaction vessel. In addition, the removed pieces removed from the lower part in contact with the inner surface of the reduction reaction vessel are classified, and the removed pieces having a large particle size are separated from the other removed pieces. Larger ones have a lower impurity concentration and are of relatively high quality, so separating removed pieces that can be reused as a raw material for stretched materials is separated and recovered by separating the removed pieces of large particle size from other removed pieces. And the reuse improves the yield. Other removed pieces after the removal pieces having a large particle diameter, that is, removed pieces having a small particle diameter, can be disposed of as defective products as usual , or can be used as raw materials for Ti additives for steel.

  The sieve aperture used for classification is preferably 10 to 200 mm, and more preferably 15 to 150 mm. If this mesh opening is too small, the quality of the removed pieces on the sieve to be classified and separated will deteriorate. That is, many small particle size removal pieces with a high impurity concentration are mixed with large particle size removal pieces with a low impurity concentration, and the quality deteriorates. On the other hand, if the opening is too small, the quality of the removed pieces on the sieve to be classified and separated is improved, but the amount of classification and separation is reduced, and the yield improvement effect is reduced. The opening here is the minor axis length of the sieve hole. For example, if the sieve hole is square, the length is one side, if it is a rectangle, the length is short, if it is a diamond, the distance between opposite sides, if it is a circle, it is the diameter, if it is oval, it is the short diameter.

  As a precaution in classification, it is desirable to prevent the fine removed pieces from adhering to the removed pieces having a large particle size separated and recovered by classification. This is because the fine removed pieces have a high impurity concentration, and the quality of the removed pieces having a large particle size is deteriorated by adhesion to the removed pieces having a large particle size. In order to prevent the fine removed pieces from adhering, it is desired that the removal of the lower part in contact with the inner surface of the reduction reaction vessel is performed on a sieve. By performing the removal operation of the lower part on the sieve, the fine removal pieces generated by the removal work fall under the sieve with almost no adhesion to the removal pieces of large particle size on the sieve, and the removal pieces of large particle size Contamination due to adhesion of fine removed pieces to the surface, and increase in the impurity concentration of the reused material due to this can be avoided as much as possible.

  It is also effective to reduce the impurity concentration of reusable materials by removing the vicinity of the contact surface with the inner surface of the reduction reaction vessel, which has a particularly high impurity concentration, for some or all of the large particle removal pieces separated and recovered by classification. It is. For some of the large particle size removal pieces that have been separated and recovered, when removing the vicinity of the contact surface with the inner surface of the reduction reaction vessel, it is reasonable to work on large particle size because workability and effect are large. is there.

  The method for producing sponge titanium particles of the present invention classifies the removed pieces from the outer periphery of the titanium sponge lump that has not been omitted in the past, particularly the removed pieces from the lower part that was in contact with the inner surface of the reduction reaction vessel. By separating the removal pieces having a diameter from other removal pieces, the removal pieces that can be reused as the wrought material can be selected and collected, and the reuse can improve the yield.

It is process drawing of the sponge titanium particle manufacturing method which shows one Embodiment of this invention. It is an image figure of the sponge titanium lump taken out from the reduction reaction container. It is an image figure of the operation | work which removes a low-order site | part from the outer peripheral part of a sponge titanium lump.

  Embodiments of the present invention will be described below with reference to the drawings. In the present embodiment, sponge titanium particles for wrought material are produced from a sponge titanium mass produced by the crawl method. The manufacturing process will be described in detail with reference to FIG.

  In the production of sponge titanium lumps by the crawl method, the sponge titanium lumps are produced through a reduction reaction step-vacuum separation step. In the reduction reaction step, Mg is loaded into the reduction reaction vessel, the Mg is melted in the heating furnace, and the vessel is filled with molten Mg. The reduction reaction vessel is a clad clad vessel or buttering vessel with stainless steel on the outer surface and iron on the inner surface, equipped with a detachable rooster made of iron at the bottom, and a small, closeable opening for pushing up the rooster. At the center of the bottom.

  In the reduction reaction step, liquid titanium tetrachloride is melted in the container through the center of the container lid with the opening provided at the center of the bottom of the reduction reaction container closed and the container filled with molten Mg. Dropped on Mg. By continuing this, a sponge titanium lump is generated on the rooster in the reduction reaction vessel. Ni, which is an impurity in the molten Mg, is gettered by the initially formed sponge titanium, and the molten Mg is purified. For this reason, the sponge titanium produced | generated in the lower part in a reduction reaction container has a high contamination degree, and conversely, the sponge titanium produced | generated after that becomes comparatively high quality.

  When the reduction reaction is completed, the sponge titanium mass generated in the reduction reaction container is taken out from the reduction reaction container after the vacuum separation process and the cooling process. As shown in FIG. 2, the sponge titanium mass produced in the reduction reaction vessel is formed in a roughly cylindrical shape along the inner surface of the vessel, but precisely, it is formed in a deformed shape having a constriction due to a difference in reaction rate or the like. Usually, the lower outer peripheral surface and the upper outer peripheral surface are in contact with the inner surface of the container over the entire periphery, but the outer peripheral surface of the middle step portion is formed in a shape like an hourglass separated from the inner surface of the container by constriction. The sponge titanium mass generated in the reduction reaction vessel is taken out by inserting a push rod from the opening provided at the center of the bottom surface and pushing up the rooster with the vessel lid of the reduction reaction vessel opened. .

  As shown in FIG. 2, the titanium sponge lump 10 taken out from the reduction reaction vessel is used as a product except for the outer peripheral portion and the lower portion of the bottom portion. In the outer peripheral portion removal, the operator removes the cylindrical portions 11 and 12 that are in contact with the inner surface of the vessel from the outer peripheral portion of the sponge titanium lump 10 using a machine tool, for example, a small rock drill called a chipper. To do. Further, the constricted portion 13 that is not in contact with the inner surface of the container is removed by a machine tool such as a small rock drill called a chipper while the operator visually observes the portion where the nitride is concentrated. In the bottom removal, the bottom 14 in which impurities are concentrated by gettering at the beginning of the reaction is cut and removed by a press blade.

  The titanium sponge lump from which the lower part has been removed is roughly divided by a press blade. The obtained sponge titanium piece (large piece) is divided by a multistage cutting machine. The obtained titanium sponge piece (small piece) is divided by a crusher such as a jaw crusher. Thus, granular sponge titanium is obtained. The obtained sponge titanium particles are packed in a container through a classification process.

  What is important in the present embodiment is a step of removing the outer periphery of the titanium sponge lump, particularly a step of removing the entire circumference of the cylindrical portions 11 and 12 that are in contact with the inner surface of the container in the outer peripheral portion of the sponge titanium lump 10. In the outer peripheral portion removal process of the sponge titanium lump, as shown in FIG. 3, the sponge titanium lump 10 is laid sideways and placed on the rollers 21 and 21 in a rotatable manner. In order to rotate the sponge titanium lump 10 on the rollers 21 and 21, a chain 22 is hung on the sponge titanium lump 10 from below. The worker performs work on the work floor 20. The work floor 20 also serves as a sieve, and is constituted by a combination lattice member of vertical members and cross members having mechanical strength such as grating. The sieve opening is preferably 10 to 200 mm, more preferably 15 to 150 mm, and here it is set to 100 mm.

  In the step of removing the outer peripheral portion of the titanium sponge lump, in particular, in the step of removing the entire circumference of the cylindrical portions 11 and 12 that were in contact with the inner surface of the outer periphery of the titanium sponge lump 10, the operator stands on the work floor 20. Then, using a machine tool, for example, a small rock drill called a chipper, the upper half circumferential portions of the cylindrical portions 11 and 12 lying on the rollers 21 and 21 are removed at a predetermined depth. When the removal of the upper half circumference is completed, the chain 22 is driven to rotate the sponge titanium lump 10 on the rollers 21 and 21 by 180 degrees. As a result, the unremoved portion is on the upper side, and this portion is removed. In this way, the entire circumference of the cylindrical portions 11 and 12 is removed over the entire circumference at a predetermined depth. The removal depth is about 20 mm on average.

  In this removal operation, removal pieces of various sizes fall from the cylindrical portions 11 and 12 of the sponge titanium lump 10. The removed removed pieces fall onto the work floor 20 which also serves as a sieve, the removed pieces having a larger particle size larger than the opening size remain on the working floor 20, and the removed particles having a smaller particle size smaller than the opening size are worked. Fall under the floor 20. As a result, the large particle size removal pieces are separated from the small particle size removal pieces without being mixed with the small particle size removal pieces. The removed piece having a large particle size remaining on the work play 20 is collected and reused as a wrought material. The removed pieces dropped under the work floor 20 are collected as steel Ti additive material.

  Among the removal pieces having a large particle diameter on the sieve, particularly those having a large particle size can be further removed by thinly removing the vicinity of the contact surface with the inner surface of the container to further reduce the Fe concentration. Thereby, the quality of the wrought material and the wrought material using the wrought material can be further improved.

  In the step of removing the outer peripheral portion of the constricted portion 13 that is not in contact with the inner surface of the container, the operator removes the portion where the nitride is concentrated with a machine tool, for example, a small rock drill called a chipper, while visually observing the portion. It is not particularly problematic that the nitride enriched pieces are mixed with the Fe enriched pieces removed from the cylindrical portions 11 and 12 of the sponge titanium lump 10.

  A sponge titanium lump for high-grade wrought material was actually produced by the crawl method (a titanium production amount per batch of 8 tons, a container inner diameter of 2000 mm, and the Fe concentration in the high-grade wrought material was 1000 ppm or less). When the sponge titanium lump for high-grade wrought material is produced, it is laid down on a roller as shown in FIG. 3, and the upper part of the outer periphery of the titanium sponge lump that is in contact with the inner surface of the reduction reaction vessel The lower part and the lower part were removed over the entire circumference with a thickness of 20 mm on average by an operator using a small rock drill called a chipper. The removal amount was 250 kg.

  As a conventional example, all of the removed strips were used for the steel Ti additive material. That is, the removed removed piece was not reused for the wrought material. The titanium sponge particles obtained by this method were processed into a consumable electrode and vacuum-dissolved using this to produce a titanium ingot for high-quality wrought material. The removal piece was not collected and reused, and the removal rate (reuse rate) of the removal piece was 0%. Therefore, there was no problem in the quality of the titanium ingot for high-quality wrought material.

  As Example 1, the outer peripheral portion removing work was performed on a normal work floor. All the removed pieces on the work floor were collected, classified by a sieve having an opening of 100 mm, and the large particle size removed pieces on the sieve were pulverized and reused in the production of the lower wrought material by the same method as in the conventional example. The removed piece collected for reuse is about 100 kg, and the collection rate (reuse rate) of the removed piece is 40% by weight with respect to the total amount of the removed piece. The Fe concentration in the lower wrought material is 1500 ppm or less. There was no problem in the Fe concentration of the produced lower wrought material.

  As Example 2, the outer peripheral portion removing work was performed on a work floor that also served as a sieve having an opening of 100 mm. About 100 kg of large particle size-removed pieces were separated and collected in total on the work floor. The recovered large particle size-removed pieces were pulverized and reused in the production of intermediate wrought material by the same method as in the conventional example. The recovery rate (reuse rate) of the removed pieces is 40% by weight. The Fe concentration in the intermediate wrought material is 1300 ppm or less. There was no problem in the Fe concentration of the manufactured intermediate wrought material.

  As Example 3, the vicinity of the contact surface of the large particle size removal piece collected on the work floor also serving as a sieve, which was in contact with the inner surface of the container, was deleted with a chipper to a thickness of about 10 mm. The recovered large particle size removed piece after surface cutting was pulverized and reused in the production of high-quality wrought material by the same method as in the conventional example. The recovery rate (reuse rate) of the removed pieces is 30% by weight. The Fe concentration in the high-quality wrought material is 1000 ppm or less. There was no problem in the Fe concentration of the manufactured high-quality wrought material.

  Presence / absence of reuse of removed pieces in Comparative Example and Examples 1-3, presence / absence and details of classification upon reuse, highest grade of stretchable material that can be used for collected removed pieces, recovery rate of removed pieces (reuse rate) ) Are shown in Table 1. Table 1 also shows the number of man-hours required for reuse of the removed piece as 100 in the case of Example 1.

  As can be seen from Table 1, of the outer peripheral portion of the titanium sponge lump, the removed pieces generated from the portion that was in contact with the inner surface of the reduction reaction vessel can be reused by sorting and collecting the large particle size pieces by classification, Needless to say, this improves yield. Although the purity is reduced by reuse, it can be reused by lowering the grade of the wrought material to be applied. When the vicinity of the surface in contact with the inner surface of the container of the collected large particle size removal piece is removed, it can be used for producing a wrought material of the same grade. When the lower part is removed on the working floor that also serves as a sieve, the classification is not troublesome, and relatively high-grade removed pieces are collected.

  Comparative Examples and Examples 1 to 3 show the case of producing a sponge titanium lump for high-grade wrought material, but the tendency is the same when producing a sponge titanium lump for intermediate-grade wrought material. The large particle size-removed pieces collected on the floor can be used for the production of the lower wrought material. If the surface of the large particle size-removed piece that is in contact with the inner surface of the container is removed, It can be used for manufacturing. Similarly, when producing a sponge titanium lump for a lower wrought material, the lower wrought material is removed by removing the vicinity of the surface that was in contact with the inner surface of the container of the large particle size removal piece collected on the work floor that also serves as a sieve. Can be used for manufacturing.

DESCRIPTION OF SYMBOLS 10 Titanium sponge lump 11,12 Cylindrical part 13 Constricted part 14 Bottom part 20 Work floor which also serves as a sieve 21 Roller 22 Chain

Claims (2)

When producing a titanium sponge particle by cutting and crushing a sponge titanium mass produced by a crawl method in a reduction reaction vessel and taken out from the reaction vessel, at least the inner surface of the sponge titanium mass is in contact with the inner surface of the reduction reaction vessel. The removed part removed from the lower part that was in contact with the inner surface of the reduction reaction vessel was classified with a sieve having an opening of 10 to 200 mm to separate the removed part having a large particle size from other removed parts. is recovered, for some or all of the removed pieces of large particle size separated recovered by classification, to remove the contact surface near the reduction reaction vessel inner surface, wrought material removed pieces of the large grain size thereafter As a method for producing titanium sponge particles, the other removed pieces are disposed of as defective products or recovered as Ti additive for steel.   2. The method for producing sponge titanium particles according to claim 1, wherein the removal of the lower part in contact with the inner surface of the reduction reaction vessel is performed on a sieve.

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