Method for manufacturing raw materials for titanium ingots and method for manufacturing titanium ingots

Abstract

This invention provides a method for producing raw materials for titanium ingots that can effectively utilize iron-containing sponge titanium. [Solution] A method for manufacturing raw materials for titanium ingots, comprising: an acquisition step of obtaining iron-containing sponge titanium; a measurement step of measuring the iron content of 30 or more lots of the iron-containing sponge titanium obtained in the acquisition step and obtaining measured values ​​for the iron content of each measured lot; a calculation step of calculating the average value of the measured values ​​of each measured lot obtained in the measurement step; and a mixing step of determining the amount of iron-containing sponge titanium to be included in the raw materials for manufacturing titanium ingots based on the average value obtained in the calculation step, and mixing the iron-containing sponge titanium into the raw materials for manufacturing.

Description

【Technical Field】 【0001】 The present invention relates to a method for producing a raw material for producing a titanium-based ingot and a method for producing a titanium-based ingot. 【Background Art】 【0002】 TiAl alloy is a functional material having high strength, excellent corrosion resistance and excellent heat resistance, and is widely used in the aircraft field and the like. As such TiAl alloy, for example, Ti-6Al-4V and Ti-48Al-2Cr-2Nb are known. 【0003】 However, additive elements such as V, Cr, Nb are relatively expensive. In recent years, as an alternative to the above TiAl alloy, Ti-5Al-1Fe, Ti-5Al-2Fe, etc. containing Fe, which is advantageous in terms of cost, have attracted attention. 【0004】 For example, in Patent Document 1, "iron chips melted by the blast furnace / converter method and sponge titanium as a raw material for metal melting are blended so that the average value of iron becomes 0.030 wt%, and after filling into an Archimedes can, the Archimedes can is rotated and supplied into a hearth pool in which molten metal is held by electron beam irradiation, and at the same time, the titanium molten metal melted and generated by charging into the hearth is discharged into a mold to continuously melt a rectangular ingot", a method for adjusting the iron concentration of a rectangular ingot (ingot) is described (see paragraph 0037 of Patent Document 1). 【Prior Art Documents】 【Patent Documents】 【0005】 【Patent Document 1】 Japanese Patent Application Laid-Open No. 2014-31551 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0006】 Incidentally, sponge titanium, which is used as a titanium raw material when obtaining titanium ingots, is industrially manufactured by the Kroll process. The industrial manufacturing process of sponge titanium using the Kroll process is broadly divided into three steps: the chlorination step, the reduction and separation step, and the crushing step. In the reduction and separation step, a reduction reaction occurs when titanium tetrachloride is dropped onto molten metallic magnesium stored in a metal reduction reaction vessel, and a sponge titanium mass is produced. In this case, iron components originating from the metal reduction reaction vessel are transferred to the sponge titanium mass being produced via the molten metallic magnesium during the reduction reaction. Therefore, there are areas with a relatively high iron content, especially in the outer periphery of the sponge titanium mass. Since extremely high-purity sponge titanium is required as a titanium raw material for titanium ingots, the outer periphery of the sponge titanium mass is removed, for example, by chipping, to obtain the sponge titanium to be used as a titanium raw material from the sponge titanium mass. 【0007】 In this context, sponge titanium with a high iron content, such as that obtained from the outer periphery of a sponge titanium ingot, separate from the sponge titanium used as a raw material for titanium, is unsuitable for applications in the aerospace sector, where high levels of purity are required. Therefore, the current use of such iron-containing sponge titanium is limited to applications such as steel additives. Consequently, there is a demand for ways to add higher value to iron-containing sponge titanium. 【0008】 Therefore, according to one embodiment of the present invention, the objective is to provide a method for manufacturing raw materials for titanium ingots that can effectively utilize iron-containing sponge titanium. Furthermore, the objective is to provide a method for manufacturing titanium ingots that can stably produce titanium ingots of a predetermined composition. [Means for solving the problem] 【0009】 The inventors of the present invention have conducted diligent research to solve the above problems and have found that by determining the amount of iron-containing sponge titanium to be included in the raw material for manufacturing titanium ingots based on a predetermined average value, and by mixing the iron-containing sponge titanium with the manufacturing raw material, it is possible to provide a titanium ingot that can effectively utilize the iron-containing sponge titanium. The present invention was completed based on the above findings and is illustrated below. [1] A method for manufacturing raw materials for titanium ingots, Acquisition steps to obtain iron-containing sponge titanium, A measurement step is to measure the iron content of 30 or more lots of the iron-containing sponge titanium obtained in the acquisition step, and to obtain the measured value of the iron content of each lot that was the subject of measurement. A calculation step of calculating the average value of the measurement values ​​of each measurement lot obtained in the measurement step, A method for producing a raw material for a titanium ingot, comprising: determining the amount of iron-containing sponge titanium to be included in the raw material for the production of a titanium ingot based on the average value obtained in the calculation step; and a mixing step of mixing the iron-containing sponge titanium with the raw material for the production. [2] A method for producing a raw material for a titanium ingot of [1], comprising: determining that the iron content of a measurement-omitted lot obtained in the acquisition step, which was not measured for iron content in the measurement step and was not used in the calculation step, is the average value, and mixing the measurement-omitted lot with the raw material for production in the mixing step. [3] A method for producing a raw material for manufacturing titanium ingots of [1] or [2], wherein the average value obtained in the calculation step is within the range of 0.1% by mass or more and 1.0% by mass or less. [4] A method for producing raw materials for titanium ingots [3], wherein the measured value of the iron content of each measurement lot obtained in the measurement step is 0.05% by mass or more. [5] A method for producing any of the raw materials for production described in [1] to [4], wherein the iron-containing sponge titanium in the acquisition step is a chipping material obtained from a sponge titanium mass produced by dropping titanium tetrachloride into molten metallic magnesium. [6] A method for producing a raw material for a titanium ingot, any of [1] to [5], wherein the iron content in the titanium ingot produced is in the range of 0.02% by mass or more and 4% by mass or less. [7] A method for manufacturing titanium ingots, comprising a manufacturing step of melting the raw material for manufacturing titanium ingots obtained by any of the methods for manufacturing raw materials for manufacturing titanium ingots described in [1] to [6], to manufacture titanium ingots. [8] The method for manufacturing a titanium ingot, according to [7], further comprising one or more titanium content adjusting materials selected from sponge titanium, titanium briquettes, titanium scrap, and titanium oxide materials as raw materials for manufacturing the titanium ingot. [9] A method for manufacturing titanium ingots according to [7] or [8], wherein the manufacturing process uses an electron beam melting furnace.

[10] A method for manufacturing a titanium ingot, wherein the iron content in the titanium ingot is in the range of 0.02% by mass or more and 4% by mass or less, according to any of [7] to [9]. [Effects of the Invention] 【0010】 According to one embodiment of the present invention, a method for manufacturing raw materials for titanium ingots is provided that can effectively utilize iron-containing sponge titanium. Furthermore, a method for manufacturing titanium ingots that can stably produce titanium ingots of a predetermined composition is provided. [Brief explanation of the drawing] 【0011】 [Figure 1] Figures 1(A) to 1(D) are cross-sectional views showing each step of an example of a measurement method in one embodiment of the method for producing raw materials for titanium ingots according to the present invention. [Figure 2]It is a schematic diagram showing the internal structure of the electron beam melting furnace used in Examples 1 to 2 and Comparative Example 1. [Figure 3] It is a graph showing the iron content of each lot in Example 1. 【Mode for Carrying Out the Invention】 【0012】 The present invention is not limited to the embodiments described below, and components can be modified and embodied without departing from the gist thereof. Also, various inventions can be formed by appropriately combining a plurality of components disclosed in each embodiment. For example, an invention may be formed by deleting some components from all the components shown in the embodiment. In the drawings, there are also members shown schematically to assist in understanding the embodiments and the like included in the invention, and the sizes, positional relationships, etc. shown in the drawings may not always be accurate. 【0013】 [1. Method for Producing Raw Material for Manufacturing Titanium-Based Ingot] In one embodiment of the method for producing a raw material for manufacturing a titanium-based ingot according to the present invention, it includes an acquisition step, a measurement step, a calculation step, and a mixing step. In one embodiment, it is important to calculate the average value of the measured values of the iron content in 30 or more lots of iron-containing sponge titanium and determine the content of iron-containing sponge titanium to be included in the raw material for manufacturing the titanium-based ingot based on that average value. 【0014】 The iron-containing sponge titanium is obtained, for example, as a hanging material obtained from a sponge titanium mass produced by dropping titanium tetrachloride into molten metal magnesium in a metal reduction reaction vessel, that is, sponge titanium removed from the sponge titanium mass by performing, for example, hanging operations (cutting, cutting, pulverizing, etc.) on the outer peripheral portion of the sponge titanium mass. When such iron-containing sponge titanium is mixed with a raw material for producing a titanium-based ingot to produce a titanium-based ingot, conventionally, the iron content of the titanium-based ingot may deviate significantly from the target range. The reasons for this are as follows. When the obtained iron-containing sponge titanium is stored in a storage container such as a drum can and taken as one lot, the variation in the iron content for each grain constituting the iron-containing sponge titanium within the lot is very large. Therefore, even if some iron-containing sponge titanium grains contained in the lot are extracted and the iron content of those grains is analyzed, the analysis value may not represent the iron content of the entire lot. From this, when producing a titanium-based ingot by mixing iron-containing sponge titanium with a raw material for producing a titanium-based ingot based on the analysis value of the iron content of the lot, the iron content in the titanium-based ingot may deviate significantly from within the target range. 【0015】 Taking the above circumstances into consideration, the inventor has repeatedly tried various experiments and examined data in order to effectively utilize iron-containing sponge titanium as a raw material for producing a titanium-based ingot. As a result, unexpectedly, it was found that by measuring the iron content of each lot for 30 or more lots and using the average value of those measurement values, the iron content of the titanium-based ingot becomes stable. That is, using the above average value provides higher control accuracy of the iron content in the titanium-based ingot than using the measurement values of each lot. 【0016】 Also, whether the metal reduction reaction vessel is made of stainless steel or clad steel, the inside of the metal reduction reaction vessel is well maintained before the reduction separation process, and the general outline of the reduction separation process is similar, so it is considered that the hanging material has a specific similarity in the iron content and its variation. From the above, the above average value can also be applied to lots that were not targeted when obtaining the above average value. The following describes preferred embodiments of each step. 【0017】 <Acquisition Steps> In the acquisition step, iron-containing titanium sponge is obtained. At least 30 lots of iron-containing titanium sponge are obtained to be used for measuring the iron content in the measurement step described later. Here, as iron-containing titanium sponge, titanium sponge produced by the Chroll method, or more specifically, chipping material obtained from titanium sponge lumps produced by dropping titanium tetrachloride into molten metallic magnesium in a metal reduction reaction vessel, can be used. This chipping material is obtained by chipping the outer periphery of titanium sponge lumps with a relatively high iron content. 【0018】 In this specification, "lot" refers to an aggregate of iron-containing sponge titanium particles, and each lot may be handled in a storage container such as a drum. The unit of a lot can be set as appropriate and can be a unit of the raw material sponge titanium mixture, a drum unit, a daily unit, etc. However, it is preferable to unify the unit across lots. For example, if the unit of a lot is a storage container unit, it is preferable that the unit of all lots is a storage container. In addition, there is no particular limit to the weight per lot, but considering the variation in iron content between lots, the lower limit is, for example, 50 kg or more. 【0019】 The relationship between a lot and a sponge titanium block will be explained further. For example, a lot may be composed solely of chipped material obtained from the same sponge titanium block, or it may be composed of chipped material obtained from multiple sponge titanium blocks manufactured under similar conditions (e.g., type of metal reduction reaction vessel and schedule of reduction separation process). 【0020】 <Measurement Steps> In the measurement step, the iron content of each of the 30 or more lots of iron-containing titanium sponge obtained in the acquisition step is measured, and the measured iron content of each measured lot is obtained. The iron content may be measured for all lots of iron-containing titanium sponge obtained in the acquisition step, or it may be measured for only a portion of the lots if there are 30 or more lots. For example, if 100 lots of iron-containing titanium sponge are obtained in the acquisition step, the iron content may be measured for 30 of those lots. 【0021】 (Iron content of each lot) The measured iron content of each measurement lot used in the calculation steps described later is not particularly limited, but considering that the iron content of the titanium ingot should be within a predetermined target range, the iron content of each measurement lot is set to, for example, 0.05 mass% or more on the lower end and 1.5 mass% or less on the upper end. 【0022】 (An example of measurement) An example of a method for measuring the iron content of iron-containing titanium sponge (steps (1) to (7)) is shown below. (1) A titanium foil is used as a partition plate 111 in the storage section 110 of the dissolution container 100, and iron-containing sponge titanium granules 10 weighing approximately 500g to 1000g are placed on the titanium foil (see Figure 1(A)). (2) The surrounding atmosphere of the dissolution container 100 is made into an inert gas (argon gas) atmosphere. (3) Under the inert gas atmosphere described above, the iron-containing sponge titanium particles are melted by plasma generated from the heat source 21 of the plasma torch 20, thereby forming molten iron-containing sponge titanium 11 in the containment section (see Figure 1(B)). (4) Approximately one minute after the molten metal 11 is formed, the titanium foil is melted by plasma (see Figure 1(C)). (5) After the titanium foil has melted, the molten iron-containing sponge titanium 11 in the containment section 110 is poured into the mold section 120 while maintaining an inert gas atmosphere, and the molten metal 11 is cooled and solidified in the water-cooled mold section 120 (see Figure 1(D)). (6) The surrounding atmosphere is changed to an atmospheric atmosphere, and the iron-containing titanium cast slab 12 obtained by solidification is removed from the melting container 100. (7) A sample is taken from near the center of the iron-containing titanium slab 12, and the iron content of the sample is measured using an X-ray fluorescence analyzer. 【0023】 <Calculation Steps> In the calculation step, the average value of the measured values ​​for each measurement lot obtained in the measurement step described above is calculated. For example, if the iron content is measured in only a portion of the iron-containing sponge titanium lot obtained in the acquisition step during the measurement step, the average value can be calculated using the measurement results of that portion, and the iron content of the remaining lot (the lot where measurement was omitted) of the iron-containing sponge titanium can be considered to be the above average value without further measurement. 【0024】 <Mixing step> The mixing step determines the amount of iron-containing sponge titanium to be included in the raw material for manufacturing titanium ingots based on the average value obtained in the calculation step, and mixes the iron-containing sponge titanium with the manufacturing raw material. When titanium ingots are manufactured using such a manufacturing raw material, the iron content of the titanium ingots tends to fall within the target range. The manufacturing raw material for titanium ingots is melted, and the resulting molten metal is used to manufacture titanium ingots. 【0025】 Furthermore, the iron content of a measurement-omitted lot obtained in the acquisition step, which was not measured in the measurement step and was not used in the calculation step, may be considered to be the average value. In this case, the measurement-omitted lot can be mixed with the raw materials for production. The iron content of a lot produced later can also be considered to be the above average value (i.e., treated as a measurement-omitted lot). 【0026】 (Average value) The average value used when incorporating iron-containing sponge titanium into the raw materials for manufacturing titanium ingots in the mixing step is not particularly limited, but from the viewpoint of stably producing titanium ingots with an iron content within the target range, it is preferable that it be in the range of 0.1% by mass or more and 1.0% by mass or less. 【0027】 (Iron content in titanium ingots) The iron content in the titanium ingot can be determined appropriately according to the customer's requirements, but for example, it is within the range of 0.02% by mass to 4% by mass. Within this range, titanium ingots include pure titanium ingots and Ti-Al-Fe alloy ingots, and more specifically, Ti-5Al-1Fe and Ti-5Al-2Fe are examples of Ti-Al-Fe alloy ingots. In order to control the iron content within the above range, for example, in addition to iron-containing sponge titanium, the following titanium content adjusting materials may be mixed into the raw materials for manufacturing titanium ingots. 【0028】 (Raw material for the manufacture of titanium ingots) The raw materials for manufacturing titanium ingots may include, in addition to iron-containing titanium sponge, titanium content adjusting materials. Known titanium, titanium alloys, or titanium-containing compounds can be used as titanium content adjusting materials, and their shapes can also be selected as appropriate. Examples of such titanium content adjusting materials include titanium sponge (obtained by crushing titanium sponge ingots using the Kroll process), titanium briquettes, titanium scrap, and titanium oxide materials (oxygen source). When manufacturing Ti-Al-Fe alloy ingots, materials containing Al or Al may be used as titanium content adjusting materials. Two or more types of such titanium content adjusting materials may be used in combination. 【0029】 [2. Method for manufacturing titanium ingots] One embodiment of the method for manufacturing titanium ingots according to the present invention includes a manufacturing step of melting the raw material for manufacturing titanium ingots obtained by the method for manufacturing raw materials for manufacturing titanium ingots described above, in order to manufacture titanium ingots. 【0030】 Examples of melting techniques for raw materials used in the production of titanium ingots include the VAR method, PAM method, and EB method, but the PAM method or EB method is preferred, and the VAR method is most preferred. The VAR method has a deeper molten pool compared to the PAM method and the EB method, making it the most suitable for ensuring uniformity of the composition of the raw materials during melting. However, the EB method is also a particularly suitable embodiment, considering the balance between the ability to reduce the impurity content in the raw materials and the production capacity per unit time, as well as the degree of freedom in the shape of the cast ingots. In methods such as the VAR method, PAM method, and EB method, the equipment and manufacturing conditions can be those that are publicly known and can be used as appropriate. 【0031】 The iron content in titanium ingots is, for example, 0.02% by mass or more and 4% by mass or less. 【0032】 (An example of a method for measuring iron content) An example of a method for measuring the iron content in titanium ingots is shown below. Samples are taken from the upper (within a range of 0 to 300 mm from the upper end face to the lower end face), the central (center in the longitudinal direction), and the lower (within a range of 0 to 300 mm from the lower end face to the upper end face) of the titanium ingot in the longitudinal direction. The iron content (upper, central, and lower) of each sample is measured using an ICP emission spectrometer (Hitachi High-Tech Corporation, PS3520UVDDII). Samples for measurement may be taken from the molten metal at the corresponding locations during the manufacturing of the titanium ingot, or from the manufactured titanium ingot. [Examples] 【0033】 The present invention will be specifically described based on examples and comparative examples. The following examples and comparative examples are merely specific examples to facilitate understanding of the technical content of the present invention, and the technical scope of the present invention is not limited by these examples. 【0034】 [Preparation of iron-containing titanium sponge within the lot] (Acquisition Step) First, a sponge titanium ingot (approximate production volume: 8 tons) was produced in a clad steel metal reduction reaction vessel (outer wall: stainless steel, inner wall: carbon steel) with a cylindrical body by reducing titanium tetrachloride with metallic magnesium. After the remaining molten magnesium chloride and molten metallic magnesium were removed from the metal reduction reaction vessel via a pipe connected to the bottom of the vessel, the sponge titanium ingot was subjected to a vacuum separation treatment. Subsequently, the sponge titanium ingot was removed from the metal reduction reaction vessel. 【0035】 Next, the outer circumference (iron-containing portion) of the sponge titanium ingot was chipped away to create a roughly cylindrical shape (φ1,900mm × 2,400mm). The iron-containing sponge titanium (chipped material) obtained from the chipping process was collected. A total of 1,000 batches of sponge titanium ingots were manufactured using the same method, producing a total of 98 lots of iron-containing sponge titanium. Of course, these lots contained a large number of iron-containing sponge titanium particles. The weight of each lot was within the range of 1,000 to 2,000 kg. Furthermore, the metal reduction reaction vessel was cleaned after each batch of sponge titanium ingots was manufactured. In other words, a cleaned metal reduction reaction vessel was used in the production of the sponge titanium ingots. 【0036】 [Example 1] (Measurement step, calculation step) From the 98 lots, iron-containing sponge titanium granules were randomly sampled from the 1st to the 49th lot, and the iron content in each iron-containing titanium slab was measured using the method described above. Each measured value was taken as the measured iron content for each lot. Subsequently, the average of the measured iron content values ​​from the 1st to the 49th lot was calculated to be 0.20 mass%. The results are shown in Figure 3. Figure 3 shows the measurement results for all 98 lots, and the average measured iron content value from the 1st to the 49th lot was obtained to be 0.20 mass%. The iron content in the iron-containing sponge titanium of each lot was within the range of 0.05 mass% to 0.5 mass%. 【0037】 (Manufacturing of titanium ingots) An electron beam melting furnace (hereinafter referred to as EB furnace) 200 having the configuration shown in Figure 2 was used. The inside of the EB furnace 200 was depressurized using the vacuum pump 211 of the vacuum mechanism 210 while monitoring the pressure gauge 212, and then argon gas was supplied to bring the pressure to 2.0 × 10⁻¹⁶ in absolute pressure. -3 hPa or higher: 2.0 × 10 -2 The system was adjusted to achieve a high vacuum state in the range of hPa or less. 【0038】 (Mixing step) The target range for the iron content in the slab-type titanium ingots was set to 0.030% by mass or more and 0.050% by mass or less. To achieve a calculated blended iron content of 0.040% by mass, raw materials for the production of titanium ingots, including the 1st to 49th measurement lots, were supplied from the raw material supply mechanism 220 of the EB furnace 200 to the hearth 230. The above calculated blended iron content was calculated assuming an iron content of 0.20% by mass in each lot. 【0039】 The raw material for manufacturing the titanium ingot was melted by irradiation with an electron beam from an electron gun 240 located on the inner wall 241 of the top. The resulting molten metal 51 flowed from the front wall 232 to the rear wall 233 of the hearth 230's bath 231 and was poured into the mold 250 through a pouring port on the rear wall 233. The molten metal 51 was then solidified using a cooling means 251 located inside the mold 250. The drawing base 260 was then pulled downward to obtain a slab-type titanium ingot (thickness: 250 mm, width: 1,300 mm, length: 7,000 mm) 52. A total of 10 slab-type titanium ingots 52 were manufactured using all of each measurement lot. 【0040】 (evaluation) Using the method described above, the iron content (upper, middle, and lower parts) of the slab-type titanium ingot was measured. As a result, the iron content in the upper, middle, and lower parts of all 10 slab-type titanium ingots was within the aforementioned target range. 【0041】 [Example 2] In Example 2, the measurement-omitted lots from the 50th to the 98th lot out of the 98 lots obtained during lot preparation were used. That is, the iron content of each measurement-omitted lot was assumed to be 0.20 mass%, which was the average value calculated in Example 1. The target range for the iron content in the slab-type titanium ingot was set to 0.030 mass% or more and 0.050 mass or less. The raw materials for manufacturing titanium ingots, including each measurement-omitted lot from the 50th to the 98th lot, were supplied from the raw material supply mechanism of the EB furnace to the hearth so that the calculated blend value for the iron content was 0.040 mass%, and a total of 10 slab-type titanium ingots were manufactured from these raw materials in the same manner as in Example 1. When the iron content (upper, middle, and lower parts) of 10 slab-type titanium ingots was checked under the same conditions as in Example 1, the same results as in Example 1 were obtained. 【0042】 [Comparative Example 1] The iron content in a total of 10 titanium ingots was predicted based on the following formula (1), assuming that the measured values ​​for each of the 49 iron-containing sponge titanium lots used in Example 1 were applied. Predicted value of titanium ingot [mass%] = (average value of titanium ingot [mass%] - blending value using measured values ​​for each lot [mass%]) + target value of titanium ingot [mass%] ... Equation (1) As a result, the iron content in two of the ten slab-type titanium ingots was not within the aforementioned target range. In other words, if the measurements from each lot had been used, it can be inferred that the iron content in at least one of the upper, middle, or lower parts of the two slab-type titanium ingots would not have been within the aforementioned target range. 【0043】 (Discussion based on examples) In Example 1, unlike Comparative Example 1, it was confirmed that it is useful to use the average value of the measured values ​​from 30 or more measurement lots as the iron content of the lot, and to determine the amount of iron-containing sponge titanium to be included in the raw material for manufacturing titanium ingots based on this average value. 【0044】 Furthermore, in Example 2, even when the iron content of a measurement-omitted lot obtained in the acquisition step, which was not measured in the measurement step and was not used in the calculation step, was considered to be the average value obtained in Example 1, and this measurement-omitted lot was mixed with the raw materials in the mixing step, the iron content in the production of titanium ingots could be controlled within the target range, similar to Example 1. 【0045】 Furthermore, the average value obtained in Example 1 was considered applicable to lots obtained even later than those in Example 1 and Example 2. The lot used in Example 2 was obtained at a different time than the lot used in Example 1, and the measurement and calculation steps were omitted. This is because the conditions for lots obtained even later than those in Example 1 and Example 2 overlap with those of the lot in Example 2 where the measurement was omitted. 【0046】 Based on the above, it can be inferred that in Examples 1 and 2, iron-containing sponge titanium can be effectively utilized, and furthermore, titanium-based ingots of a predetermined composition can be stably manufactured. [Explanation of Symbols] 【0047】 10 Iron-containing sponge titanium granules 11, 51 molten metal 12 Iron-containing titanium slabs 20 Plasma Torch 21 Heat source 52 Slab-type titanium ingots 100 Container for dissolving 110 Storage Unit 111 Partition plate 120 Mold section 200 Electron beam melting furnaces (EB furnaces) 210 Vacuum mechanism 211 Vacuum pump 212 Pressure gauge 220 Raw material supply mechanism 230 Haas 231 Bathtub 232 Front wall 233 Back wall 240 Electron Gun 241 Interior wall 250 molds 251 Cooling means 260 Removable base

Claims

[Claim 1] A method for manufacturing raw materials for titanium ingots, Acquisition steps to obtain iron-containing sponge titanium, A measurement step is to measure the iron content of 30 or more lots of the iron-containing sponge titanium obtained in the acquisition step, and to obtain the measured value of the iron content of each measurement lot that was the subject of measurement, A calculation step of calculating the average value of the measurement values ​​of each measurement lot obtained in the measurement step, A method for producing a raw material for a titanium ingot, comprising: determining the amount of iron-containing sponge titanium to be included in the raw material for the production of a titanium ingot based on the average value obtained in the calculation step; and a mixing step of mixing the iron-containing sponge titanium with the raw material for the production. [Claim 2] A method for producing a raw material for a titanium ingot according to claim 1, wherein the iron content of a measurement-omitted lot obtained in the acquisition step, which was not measured for iron content in the measurement step and was not used in the calculation step, is considered to be the average value, and the measurement-omitted lot is mixed with the raw material for production in the mixing step. [Claim 3] A method for producing a raw material for a titanium ingot according to claim 1, wherein the average value obtained in the calculation step is within the range of 0.1% by mass or more and 1.0% by mass or less. [Claim 4] The method for producing a raw material for a titanium ingot according to claim 3, wherein the measured value of the iron content of each measurement lot obtained in the measurement step is 0.05% by mass or more. [Claim 5] The method for producing a raw material for manufacturing a titanium ingot according to claim 1, wherein the iron-containing sponge titanium in the acquisition step is a chipping material obtained from a sponge titanium mass produced by dropping titanium tetrachloride into molten metallic magnesium. [Claim 6] A method for producing a raw material for a titanium ingot according to claim 1, wherein the iron content in the titanium ingot produced is in the range of 0.02% by mass or more and 4% by mass or less. [Claim 7] A method for manufacturing a titanium ingot, comprising a manufacturing step of melting the raw material for manufacturing a titanium ingot obtained by the method for manufacturing a raw material for manufacturing a titanium ingot according to any one of claims 1 to 6, to manufacture a titanium ingot. [Claim 8] The method for manufacturing a titanium ingot according to claim 7, wherein the raw material for manufacturing the titanium ingot further comprises one or more titanium content adjusting materials selected from sponge titanium, titanium briquettes, titanium scrap, and titanium oxide material. [Claim 9] The method for manufacturing a titanium ingot according to claim 7, wherein an electron beam melting furnace is used in the manufacturing process. [Claim 10] The method for producing a titanium ingot according to claim 7, wherein the iron content in the titanium ingot is in the range of 0.02% by mass or more and 4% by mass or less.

Images