Vacuum distillation device and method for preparing ultra-high purity indium balls

Abstract

The application discloses a kind of vacuum distillation device for preparing superhigh purity indium ball, including vacuum distillation furnace body and cover plate, cover plate is installed support frame, support frame hoisting has distillation condensing cover, multiple metal partitions are arranged in distillation condensing cover, the bottom layer metal partition is inserted with riser, the lower end of riser is sequentially connected with conical disc, sleeve and graphite crucible, heating coil is installed outside graphite crucible, and base is arranged in lower part.In addition, the application also provides a kind of vacuum distillation method for preparing superhigh purity indium ball, and the superhigh purity indium ball is obtained on metal partition and the inner wall of distillation condensing cover by vacuum distillation of indium metal.The indium steam generated by heating indium metal is introduced into distillation condensing cover by setting riser, conical disc and sleeve, and the indium ball formed by condensation is collected by distillation condensing cover and multiple metal partitions arranged therein, which increases the number of superhigh purity indium ball prepared, improves yield, and facilitates the indium ball to be taken out, the preparation cycle is short, and the labor cost is low.

Description

Technical Field

[0001] This invention belongs to the field of non-ferrous metal high-purity material preparation technology, specifically relating to a vacuum distillation apparatus and method for preparing ultra-high purity indium spheres. Background Technology

[0002] Currently, the demand for semiconductor materials has expanded from solely ultra-high purity rare and precious metals to include byproducts of ultra-high purity rare and precious metals. Among these, the demand for high-purity indium spheres is increasing, primarily for use in compound semiconductors, high-purity alloys, semiconductor material dopants, and contact materials. Typically, indium spheres are made from indium raw materials with a mass content of over 99.995%. The main preparation method involves melting metallic indium, then manually scooping the liquid indium into a dripping cup, where it drips under gravity into a cooling liquid through a small hole, and finally manually removing it. However, this method often results in high-purity indium spheres that are mostly ellipsoidal in shape with tadpole-like tails, leading to low product yield and high labor costs, making it difficult to meet industry demands. Another main method for preparing high-purity indium spheres involves melting metallic indium, then manually scooping the liquid indium into an indium sphere forming box, allowing it to cool naturally before removing it, thus completing the indium sphere production. However, the high-purity indium spheres prepared in this way exhibit defects such as pitting, peeling, oxidation, and roughness on their surface. Furthermore, contact with the mold surface during production can lead to contamination of the indium spheres. Additionally, these indium spheres have poor sphericity and a low sphericity ratio because the liquid indium contracts under gravity and surface tension during cooling, resulting in poor sphericity. Therefore, traditional preparation methods are insufficient to meet actual production needs, and the low purity of traditionally prepared indium spheres makes them unsuitable as raw materials for high-end semiconductor applications. Vacuum distillation, in addition to purifying rare and precious metals, can also produce high-purity, oxide-free spherical metal products.

[0003] For example, Chinese patent application number 201520423085.4, published on November 18, 2015, discloses an apparatus for producing indium spheres. The apparatus involves melting indium and placing it into a cylindrical indium sphere inlet cup, which is positioned at the top of an indium sphere forming box. The bottom of the forming box is placed in a cooling water tank, and the box contains a glycerol solution. The diameter of the inlet hole is 0.1–1.0 mm. However, this method produces indium spheres by dripping them into the cooling liquid through a small hole under gravity. This results in uneven particle size, insufficient roundness, and the spheres often becoming flat and round, sometimes with small tails. The shape is difficult to control, and production is intermittent. These problems reduce the production efficiency, yield, and sphericity of the finished indium spheres.

[0004] For example, Chinese patent application number 200810143988.1, published on May 20, 2009, discloses a method and apparatus for producing high-purity indium spheres. The method primarily involves fixing two movable clamps (upper and lower halves) with compressed air. A channel connecting the upper end of the clamps to a funnel is left. Molten indium is then poured into the funnel and flows into a mold under gravity. After cooling, the indium spheres are removed. However, this method cannot produce perfectly spherical indium spheres because there are connection marks at the contact points of the two silicone mold halves, making it impossible to form perfectly smooth spheres. Uneven heat dissipation from the indium molten surface and inconsistent cooling rates, combined with the effects of gravity and centrifugal force, directly affect the sphericity of the indium spheres. When indium molten material is cast in the open air, a large amount of oxide scale is generated, leading to a high oxygen content and reduced purity. Small holes at the edges, once filled with indium molten material, solidify and adhere to the inner wall of the tank, affecting the smooth operation of the process. Furthermore, if the amount of indium molten material is too small, it cannot fill the small holes at the edges, preventing the indium spheres from becoming spherical. Therefore, this method has serious problems.

[0005] For example, Chinese patent application number 201922282145.6, published on September 22, 2020, discloses an indium sphere forming device and indium sphere production equipment. The device mainly involves preparing a funnel cup with a hole at the bottom. Below the hole is a funnel, which is inserted into the upper end of a spiral forming tube. The forming tube is immersed in a cooling liquid within a box. During the experiment, indium is melted and poured into the funnel cup. The molten indium flows from the small hole in the funnel into the spiral forming tube, where it forms a spherical indium sphere under gravity through spiral rolling. However, this method also has significant problems. For a liquid indium droplet to maintain a stable solid spherical shape, the surface must be uniformly stressed. However, when the liquid indium droplet rolls inside the tube, the stress on each surface cannot be guaranteed to be completely consistent. Furthermore, for liquid indium to roll into a spherical indium sphere, the indium droplet must remain in a soft, molten state. This is because at excessively high temperatures, indium is in a liquid state, making it difficult for the indium droplet to maintain a spherical shape; at excessively low temperatures, the indium droplet solidifies rapidly, and no amount of rolling will result in a spherical indium sphere. Therefore, this method also has certain limitations.

[0006] All three methods described above are for preparing indium spheres. The first two methods use a funnel method to drop indium to form tiny liquid droplets, which are then cooled in a liquid cooling medium to form indium spheres. However, this method tends to produce ellipsoidal indium spheres with tails, resulting in a low yield and high labor costs. The third method uses a mold to prepare the indium spheres, but the liquid indium spheres solidify under the influence of gravity and surface tension, resulting in numerous pits and scars on the surface, leading to a very low product yield. Furthermore, all three methods use refined indium as the raw material, resulting in indium spheres with low purity, which cannot meet the current demand for ultra-high purity indium spheres in the high-end semiconductor industry. Therefore, all three methods suffer from poor product quality and high labor costs, necessitating the development of a new approach to prepare ultra-high purity indium spheres. Summary of the Invention

[0007] The technical problem to be solved by this invention is to address the shortcomings of the prior art by providing a vacuum distillation apparatus for preparing ultra-high purity indium spheres. This apparatus uses a riser pipe, a conical disk, and a sleeve to guide indium vapor generated by heating indium metal into a distillation condenser. By setting up the distillation condenser and incorporating multiple layers of metal partitions within it to collect the condensed indium spheres, the number of ultra-high purity indium spheres prepared is increased, improving the yield. Furthermore, the prepared indium spheres are easy to remove, the preparation cycle is short, and the labor cost is low.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a vacuum distillation apparatus for preparing ultra-high purity indium spheres, characterized in that the apparatus includes a vacuum distillation furnace body, the upper part of which is open and provided with a cover plate for sealing, a support frame is installed on the cover plate, and a distillation condenser hood located inside the vacuum distillation furnace body is suspended at the lower part of the support frame. The distillation condenser hood is a double-layered hollow cylinder. The support frame is provided with an inlet and an outlet for circulating cooling water into the distillation condenser hood. The distillation condenser hood is provided with multiple layers of metal partitions, which are supported by support seats installed on the inner wall of the distillation condenser hood. A rising pipe is inserted into the center of the bottom metal partition. The upper part of the rising pipe inserted into the metal partition has multiple small holes. The lower end of the rising pipe is connected to a conical disk by a thread. A sleeve is provided at the lower part of the conical disk. A graphite crucible is provided at the lower part of the sleeve. A heating coil is installed on the outside of the graphite crucible, and a base is provided at the lower part.

[0009] The above-mentioned vacuum distillation apparatus for preparing ultra-high purity indium spheres is characterized in that the vacuum distillation furnace body and the cover plate are fixed by bolts, the vacuum distillation furnace body is provided with a vacuum pumping channel, the vacuum pumping channel is connected to a vacuum pumping component, and a base is provided at the lower part of the vacuum distillation furnace body.

[0010] The above-mentioned vacuum distillation apparatus for preparing ultra-high purity indium spheres is characterized in that the distillation condenser is welded from double-layer 304 stainless steel plates, the metal partition is made of 304 stainless steel, and the inner wall of the distillation condenser, the support base and the surface of the metal partition are all coated with boron nitride coating.

[0011] The vacuum distillation apparatus for preparing ultra-high purity indium spheres described above is characterized in that multiple layers of metal partitions are placed at equal intervals from bottom to top in the distillation condenser hood, with a layer spacing of 60mm to 100mm. The metal partitions are supported by arc-shaped arch support seats welded to the inner wall of the distillation condenser hood. The outer arc length of the arch of the support seat is consistent with the outer arc length of the metal partition. The metal partition consists of two double semi-circular plates with a thickness of 2mm to 3mm.

[0012] The vacuum distillation apparatus for preparing ultra-high purity indium spheres described above is characterized in that the bottom support base is connected to the distillation condenser hood by threads, the bottom metal partition is seamlessly connected to the riser pipe, and holes and gaps are left between the metal partitions of each of the remaining layers.

[0013] The vacuum distillation apparatus for preparing ultra-high purity indium spheres described above is characterized in that the inner diameter of the riser tube is 30mm to 50mm, the height is 100mm to 200mm, the riser tube has multiple circular holes, the inner diameter of the small holes is 5mm to 10mm, and the riser tube is made of boron nitride.

[0014] The vacuum distillation apparatus for preparing ultra-high purity indium spheres described above is characterized in that the height of the sleeve is 50mm to 100mm and the thickness is 10mm to 20mm, the aperture of the sleeve is the same as the inner diameter of the graphite crucible, the sleeve is made of alumina, the conical disk is made of boron nitride, and the angle between the side wall of the graphite crucible and the horizontal plane is 85° to 89°.

[0015] The vacuum distillation apparatus for preparing ultra-high purity indium spheres described above is characterized in that the maximum loading amount of the graphite crucible does not exceed 70% of its rated capacity.

[0016] In addition, the present invention also provides a method for preparing ultra-high purity indium spheres by vacuum distillation, characterized in that the method includes the following steps:

[0017] Step 1: After adding indium metal to the graphite crucible, place the sleeve on the upper end of the graphite crucible opening. Then, connect the riser pipe and the conical disk spirally and place them on the sleeve. Next, install the metal partitions sequentially from top to bottom inside the distillation condenser hood and fix them on the support base. Adjust the distance between the distillation condenser hood and the riser pipe. Then, place the cover plate on the vacuum distillation furnace body and fix it with the fixing bolts. Next, turn on the circulating cooling water system and then turn on the vacuum pumping assembly to evacuate the vacuum distillation furnace body. When the pressure inside the vacuum distillation furnace body reaches the set value, turn on the power to start heating the indium metal. The indium metal is ultra-high purity indium with a mass purity greater than 99.995%.

[0018] Step 2: After the vacuum pressure and indium metal heating temperature in the vacuum distillation furnace from Step 1 reach the set values, keep the vacuum pressure and temperature constant and start vacuum distillation. During vacuum distillation, the indium metal condenses on the metal partition and the inner wall of the vacuum distillation furnace, and ultra-high purity indium spheres are obtained on the metal partition and the inner wall of the distillation condenser. Then, the ultra-high purity indium spheres are sieved and stored.

[0019] The method described above is characterized in that the pressure of the circulating cooling water in step one is 0.15 MPa to 0.3 MPa. Controlling the pressure of the circulating cooling water ensures the cooling effect.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1. This invention introduces indium vapor generated by heating indium metal into a distillation condenser by setting up a riser pipe, a conical disk, and a sleeve. By setting up a distillation condenser and installing multiple layers of metal partitions therein to collect the indium spheres formed by condensation, the number of ultra-high purity indium spheres prepared is increased, the yield is improved, and the prepared indium spheres are easy to remove. The preparation cycle is short and the labor cost is low.

[0022] 2. This invention provides an ultra-low vacuum pressure distillation environment by setting up a vacuum distillation furnace body and cover plate, which effectively promotes the free growth of ultra-high purity indium liquid in the form of vapor atoms on the metal partition in the condensation and collection space. Furthermore, a boron nitride coating is applied to the metal partition plate, and the coating does not wet the indium liquid. This ensures that the indium vapor forms uniform and stable indium spheres after liquefaction and solidification. Compared with the funnel method and mold forming method, the boron nitride coating utilizes the spontaneous free nucleation and growth of indium atoms, which can fully guarantee the sphericity of the indium spheres, efficiently prepare ultra-high purity indium spheres, and shorten the preparation cycle.

[0023] 3. By setting up a distillation condenser, the temperature is lower in different areas of the distillation condenser closer to the inner wall of the condenser. Therefore, the conditions for the nucleation and growth of indium vapor are different. In areas closer to the cold source, nucleation and growth occur first, while in areas with higher temperatures, nucleation and growth of indium vapor are slower. Thus, there is a certain concentration difference of indium vapor in the condensation zone, which enables the preparation of indium spheres of different sizes and specifications.

[0024] 4. The present invention has multiple small holes in the part of the metal partition inserted at the upper end of the riser pipe in order to disperse the indium vapor flow and prevent the airflow from being too large and directly filling the top.

[0025] 5. This invention is the first to propose the use of vacuum distillation technology to prepare ultra-high purity indium spheres. It has the advantages of high production efficiency, stable process, and no pollution. It can prepare a large number of ultra-high purity indium spheres at one time. It has the advantages of simple operation, short cycle and high cleanliness. If more ultra-high purity indium spheres of different sizes and specifications need to be prepared, different distillation temperatures can be set until the goal is achieved.

[0026] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the vacuum distillation apparatus for preparing ultra-high purity indium spheres according to the present invention.

[0028] Figure 2 This is a schematic diagram of the structure of a metal partition in the vacuum distillation apparatus for preparing ultra-high purity indium spheres according to the present invention.

[0029] Figure 3 This is a physical image of the ultra-high purity indium spheres prepared in Example 2 of the present invention.

[0030] Figure 4 This is a picture of the ultra-high purity indium spheres prepared in Example 2 of the present invention after sieving.

[0031] Explanation of reference numerals in the attached figures:

[0032] 1—Vacuum distillation furnace body; 1-1—Vacuum extraction channel; 1-2—Base;

[0033] 2—Cover plate; 3—Support frame; 4—Distillation condenser hood;

[0034] 5—Inlet; 6—Outlet; 7—Metal partition;

[0035] 8—Support base; 9—Rising tube; 10—Conical disk;

[0036] 11—Sleeve; 12—Graphite crucible; 13—Heating coil;

[0037] 14—Base; 15—Bolt. Detailed Implementation

[0038] The vacuum distillation apparatus for preparing ultra-high purity indium spheres according to the present invention is described in detail through Example 1.

[0039] Example 1

[0040] like Figure 1 As shown, the vacuum distillation apparatus for preparing ultra-high purity indium spheres in this embodiment includes a vacuum distillation furnace body 1. The upper part of the vacuum distillation furnace body 1 is open and equipped with a cover plate 2 for sealing. A support frame 3 is installed on the cover plate 2. A distillation condenser 4 located inside the vacuum distillation furnace body 1 is suspended from the lower part of the support frame 3. The distillation condenser 4 is a double-layered hollow cylinder. The support frame 3 is provided with an inlet 5 and an outlet 6 for circulating cooling water into the distillation condenser 4. The distillation condenser 4 is provided with multiple layers of metal... The metal partition 7 is supported by a support base 8 installed on the inner wall of the distillation condenser 4. A rising pipe 9 is inserted into the center of the bottom metal partition 7. The part of the rising pipe 9 inserted into the metal partition 7 has multiple small holes. The lower end of the rising pipe 9 is connected to a conical disk 10 by a thread. A sleeve 11 is provided at the lower part of the conical disk 10. A graphite crucible 12 is provided at the lower part of the sleeve 11. A heating coil 13 is installed on the outside of the graphite crucible 12. A base 14 is provided at the lower part.

[0041] It should be noted that a sealed reaction space is provided by setting up a vacuum distillation furnace body 1 and a cover plate 2. The distillation condenser 4 is hoisted by installing a support frame 3 on the cover plate 2. The distillation condenser 4 is a double-layered hollow cylinder, and the internal space is used for circulating cooling water. At the same time, the inlet 5 and outlet 6 of the circulating cooling water into the distillation condenser 4 are installed on the support frame 3 to achieve the cooling effect. Multiple layers of metal partitions 7 are set on the surface to collect condensate, and multiple layers are set to improve the yield. The metal partitions 7 can move freely on the support base 8. The indium spheres are disassembled for easy removal. The indium vapor generated by heating the indium metal is introduced into the distillation condenser 4 through the riser pipe 9, the conical disk 10, and the sleeve 11. Multiple small holes are opened in the part of the riser pipe 9 into which the metal partition 7 is inserted to disperse the indium vapor flow and prevent the airflow from being too large and directly poured from the top. A graphite crucible 12 is set up to hold the indium metal. A heating coil 13 is set up to heat the indium metal. A base 14 is set up to hold the graphite crucible 12. The base 14 is made of refractory material sintering.

[0042] It should be noted that the heating coil 13 is a low-to-medium frequency induction heating coil 13. The low-to-medium frequency induction heating coil 13 is evenly arranged around the graphite crucible 12 and the height of the heating zone is 90% to 95% of the height of the graphite crucible 12, which ensures that the indium metal is fully heated.

[0043] It should be noted that inlet 5 and outlet 6 are inlet pipe 5 and outlet pipe 6, respectively. Both inlet pipe 5 and outlet pipe 6 are threaded and connected to the external water circuit. The inner diameter of inlet pipe 5 and outlet pipe 6 is 10mm to 20mm. The small pipe diameter and fast water flow rate inside the pipe are conducive to rapid heat dissipation.

[0044] It should be noted that the vacuum distillation apparatus for preparing ultra-high purity indium spheres is mainly used for preparing indium spheres. However, it should be noted that this apparatus is not limited to the preparation of ultra-high purity indium spheres; it can also be used for the preparation of ultra-high purity metal spheres from other molten metals.

[0045] like Figure 1 As shown, in this embodiment, the vacuum distillation furnace body 1 and the cover plate 2 are fixed by bolts 15. A vacuum channel 1-1 is provided on the vacuum distillation furnace body 1, and a vacuum pumping assembly is connected to the vacuum channel 1-1. A base 1-2 is provided at the lower part of the vacuum distillation furnace body 1. The vacuum channel 1-1 and the vacuum pumping assembly provide a vacuum environment inside the vacuum distillation furnace body 1. The base 1-2, made of 304 stainless steel, supports the vacuum distillation furnace body 1.

[0046] In this embodiment, the distillation condenser 4 is welded from double-layered 304 stainless steel plates, and the metal partition 7 is also made of 304 stainless steel. The inner wall of the distillation condenser 4, the support base 8, and the surface of the metal partition 7 are all coated with a boron nitride coating. The boron nitride coating helps reduce the bonding force between indium vapor and the inner wall, support base 8, and metal partition 7 of the distillation condenser 4, facilitating the flow of indium vapor on its surface and making it easier to remove after condensation into indium spheres.

[0047] like Figure 1 and Figure 2 As shown, in this embodiment, the multiple layers of metal partitions 7 in the distillation condenser 4 are placed at equal intervals from bottom to top, with a layer spacing of 60mm to 100mm. The metal partitions 7 are supported by arc-shaped arch support seats 8 welded to the inner wall of the distillation condenser 4. The outer arc length of the support seat 8 is consistent with the outer arc length of the metal partition 7. The metal partition 7 consists of two double semi-circular plates with a thickness of 2mm to 3mm. By controlling the layer spacing of the metal partitions 7, it is beneficial to rapidly condense indium vapor in the distillation condenser 4, and at the same time, it can provide more condensation nucleation area for indium vapor. By limiting the thickness of the metal partitions 7, it is ensured that the prepared indium spheres are supported. By setting the arc-shaped arch support seats 8 to support the metal partitions 7, the metal partitions 7 are two double semi-circular plates, which are a split design and easy to install.

[0048] like Figure 1As shown, in this embodiment, the bottommost support base 8 is connected to the distillation condenser 4 by threads, and the bottommost metal partition 7 is seamlessly connected to the riser pipe 9. Holes and gaps are left between the remaining metal partitions 7. The threaded connection between the bottommost support base 8 and the distillation condenser 4 facilitates installation. Simultaneously, the seamless connection between the bottommost metal partition 7 and the riser pipe 9 ensures that indium vapor enters the sealed space formed by the distillation condenser 4 and the bottommost support base 8, preventing indium vapor overflow and improving yield. The holes and gaps between the metal partitions 7 facilitate the passage of indium vapor, allowing it to be evenly distributed on each metal partition 7, thus uniformly preparing indium spheres.

[0049] In this embodiment, the inner diameter of the riser pipe 9 is 30mm-50mm, and the height is 100mm-200mm. The riser pipe 9 has multiple circular holes, with the inner diameter of each hole being 5mm-10mm. The riser pipe 9 is made of boron nitride. By controlling the size of the riser pipe 9, the rate of indium vapor rise is controlled. This avoids a situation where the inner diameter is too large, resulting in a large vapor flow and the formation of numerous irregularly sized indium spheres after entering the distillation condenser 4. Therefore, maintaining a low vapor flow rate is reasonable. Only by keeping the vapor flow rate at a low level can uniform and stable spherical indium spheres be generated. By using a riser pipe 9 made of boron nitride, the binding force between indium vapor and the riser pipe is reduced, facilitating the rise of indium vapor.

[0050] In this embodiment, the sleeve 11 has a height of 50mm to 100mm and a thickness of 10mm to 20mm. The aperture of the sleeve 11 is the same as the inner diameter of the graphite crucible 12. The sleeve 11 is made of alumina, the conical disk 10 is made of boron nitride, and the angle between the side wall of the graphite crucible 12 and the horizontal plane is 85° to 89°. By controlling the size and material of the sleeve 11, the conical disk 10, and the graphite crucible 12, it is easy to completely introduce indium vapor into the distillation condenser 4. By controlling the angle between the side wall of the graphite crucible 12 and the horizontal plane to be 85° to 89°, it is easy to pour out the remaining material at the bottom of the crucible. If the diameters of the upper and lower bottoms of the crucible are the same, the remaining material will get stuck in the crucible, making it difficult to remove the material.

[0051] In this embodiment, the maximum loading amount of the graphite crucible 12 does not exceed 70% of its rated capacity. By controlling the loading amount, incomplete vacuum distillation due to excessive loading is prevented.

[0052] The method for preparing ultra-high purity indium spheres by vacuum distillation according to the present invention is described in detail through Examples 2 to 4.

[0053] Example 2

[0054] This embodiment includes the following steps:

[0055] Step 1: Add 2 kg of ultra-high purity indium metal with a mass purity of 99.99999% to the graphite crucible 12. Place the sleeve 11 on the upper end of the opening of the graphite crucible 12. Then, connect the riser pipe 9 and the conical disk 10 by screws and place them on the sleeve 11. Next, install the metal partitions 7 sequentially from top to bottom inside the distillation condenser 4 and fix them on the support base 8. Adjust the distance between the distillation condenser 4 and the riser pipe 9. Then, place the cover plate 2 on the vacuum distillation furnace body 1 and fix it with the fixing bolts 15. Then, turn on the circulating cooling water system and turn on the vacuum pumping assembly to evacuate the vacuum distillation furnace body 1. Wait until the pressure inside the vacuum distillation furnace body 1 reaches 1×10⁻⁶. -1 Pa ~ 1×10 -3 When Pa is reached, turn on the power supply and start heating the indium metal to 800℃;

[0056] Step 2: The vacuum pressure inside the vacuum distillation furnace body 1 from Step 1 is 1×10⁻⁶. -1 Pa ~ 1×10 -3 After the temperature of Pa and indium metal reaches 800℃, vacuum distillation is started for 5 hours while maintaining constant vacuum pressure and temperature. During vacuum distillation, indium metal condenses on the inner wall of the metal partition 7 and the vacuum distillation furnace body 1. After vacuum distillation, the graphite crucible 12 is allowed to cool naturally. Each layer of metal partition 7 is then removed in sequence. The ultra-high purity indium balls on the inner wall of the metal partition 7 and the distillation condenser 4 are brushed off with a clean soft brush. Then, the ultra-high purity indium balls of different sizes are sieved using a mesh screen, classified and stored, and labeled.

[0057] Figure 3 Here is a physical image of the ultra-high purity indium spheres prepared in this embodiment. Figure 3 As can be seen from the image, the ultra-high purity indium spheres prepared in this embodiment have a spherical structure.

[0058] Figure 4 This is a photograph of the ultra-high purity indium spheres prepared in this embodiment after sieving. Figure 4 As can be seen from the image, the ultra-high purity indium spheres prepared in this embodiment have a spherical structure.

[0059] The ultra-high purity indium spheres prepared in this embodiment were subjected to chemical composition testing. The results are shown in Table 1, indicating that the ultra-high purity indium spheres prepared in this embodiment meet the standard of 7N ultra-high purity indium. It is worth noting that at 10... -1 ~10 -3 In the vacuum distillation environment of Pa, the content of impurity elements in ultra-high purity indium metal is very low. High-boiling-point impurity elements will still remain at the bottom of the crucible under low temperature and high vacuum conditions, while most low-boiling-point impurity elements will be extracted by the vacuum pump when they are in the atomic state. Finally, the purity of the newly prepared ultra-high purity indium spheres is greater than 7N.

[0060] Table 1

[0061]

[0062] Example 3

[0063] This embodiment includes the following steps:

[0064] Step 1: Add 2 kg of ultra-high purity indium metal with a mass purity of 99.99999% to the graphite crucible 12. Place the sleeve 11 on the upper end of the opening of the graphite crucible 12. Then, connect the riser pipe 9 and the conical disk 10 by screws and place them on the sleeve 11. Next, install the metal partitions 7 sequentially from top to bottom inside the distillation condenser 4 and fix them on the support base 8. Adjust the distance between the distillation condenser 4 and the riser pipe 9. Then, place the cover plate 2 on the vacuum distillation furnace body 1 and fix it with the fixing bolts 15. Then, turn on the circulating cooling water system and turn on the vacuum pumping assembly to evacuate the vacuum distillation furnace body 1. Wait until the pressure inside the vacuum distillation furnace body 1 reaches 1×10⁻⁶. -1 Pa ~ 1×10 -3 When Pa is reached, turn on the power supply to start heating the indium metal to 900℃;

[0065] Step 2: The vacuum pressure inside the vacuum distillation furnace body 1 from Step 1 is 1×10⁻⁶. -1 Pa ~ 1×10 -3 After the temperature of Pa and indium metal reaches 900℃, vacuum distillation is started for 5 hours while maintaining constant vacuum pressure and temperature. During vacuum distillation, indium metal condenses on the inner wall of the metal partition 7 and the vacuum distillation furnace body 1. After vacuum distillation, the graphite crucible 12 is allowed to cool naturally. Each layer of metal partition 7 is then removed in sequence. The ultra-high purity indium balls on the inner wall of the metal partition 7 and the distillation condenser 4 are brushed off with a clean soft brush. Then, the ultra-high purity indium balls of different sizes are sieved using a mesh screen, classified and stored, and labeled.

[0066] The ultra-high purity indium spheres prepared in this embodiment were subjected to chemical composition testing. The results showed that the ultra-high purity indium spheres prepared in this embodiment met the standard of 7N ultra-high purity indium.

[0067] Example 4

[0068] This embodiment includes the following steps:

[0069] Step 1: Add 2 kg of ultra-high purity indium metal with a mass purity of 99.99999% to the graphite crucible 12. Place the sleeve 11 on the upper end of the opening of the graphite crucible 12. Then, connect the riser pipe 9 and the conical disk 10 by screws and place them on the sleeve 11. Next, install the metal partitions 7 sequentially from top to bottom inside the distillation condenser 4 and fix them on the support base 8. Adjust the distance between the distillation condenser 4 and the riser pipe 9. Then, place the cover plate 2 on the vacuum distillation furnace body 1 and fix it with the fixing bolts 15. Then, turn on the circulating cooling water system and turn on the vacuum pumping assembly to evacuate the vacuum distillation furnace body 1. Wait until the pressure inside the vacuum distillation furnace body 1 reaches 1×10⁻⁶. -1 Pa ~ 1×10 -3 When Pa is reached, turn on the power supply and start heating the indium metal to 850°C;

[0070] Step 2: The vacuum pressure inside the vacuum distillation furnace body 1 from Step 1 is 1×10⁻⁶. -1 Pa ~ 1×10 -3 After the temperature of Pa and indium metal reaches 850℃, vacuum distillation is started for 5 hours while maintaining constant vacuum pressure and temperature. During vacuum distillation, indium metal condenses on the inner wall of the metal partition 7 and the vacuum distillation furnace body 1. After vacuum distillation, the graphite crucible 12 is allowed to cool naturally. Each layer of metal partition 7 is then removed in sequence. The ultra-high purity indium balls on the inner wall of the metal partition 7 and the distillation condenser 4 are brushed off with a clean soft brush. Then, the ultra-high purity indium balls of different sizes are sieved using a mesh screen, classified and stored, and labeled.

[0071] The ultra-high purity indium spheres prepared in this embodiment were subjected to chemical composition testing. The results showed that the ultra-high purity indium spheres prepared in this embodiment met the standard of 7N ultra-high purity indium.

[0072] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A vacuum distillation apparatus for preparing ultra-high purity indium spheres, characterized in that, The device includes a vacuum distillation furnace body (1), the upper part of which is open and equipped with a cover plate (2) for sealing. A support frame (3) is installed on the cover plate (2). A distillation condenser hood (4) located inside the vacuum distillation furnace body (1) is suspended at the lower part of the support frame (3). The distillation condenser hood (4) is a double-layered hollow cylinder. The support frame (3) is provided with an inlet (5) and an outlet (6) for circulating cooling water into the distillation condenser hood (4). The distillation condenser hood (4) is provided with multiple layers of metal partitions (7). The metal partitions (7) are supported by support seats (8) installed on the inner wall of the distillation condenser hood (4). The bottom layer of the metal partitions (7) contains... The riser tube (9) is inserted into the core. The part of the riser tube (9) into which the metal partition (7) is inserted has multiple small holes. The lower end of the riser tube (9) is connected to a conical disc (10) by a thread. A sleeve (11) is provided at the lower part of the conical disc (10). A graphite crucible (12) is provided at the lower part of the sleeve (11). A heating coil (13) is installed on the outside of the graphite crucible (12). A base (14) is provided at the lower part. The distillation condenser (4) is welded from double-layer 304 stainless steel plates. The metal partition (7) is made of 304 stainless steel. The inner wall of the distillation condenser (4), the support base (8) and the surface of the metal partition (7) are all coated with boron nitride coating. The method for preparing ultra-high purity indium spheres by vacuum distillation using the aforementioned apparatus includes the following steps: Step 1: After adding indium metal to the graphite crucible (12), place the sleeve (11) at the upper end of the opening of the graphite crucible (12). Then, connect the riser pipe (9) and the conical disk (10) with a spiral and place them on the sleeve (11). Then, install the metal partition (7) from top to bottom inside the distillation condenser hood (4) and fix it on the support base (8). Adjust the distance between the distillation condenser hood (4) and the riser pipe (9). Then, place the cover plate (2) on the vacuum distillation furnace body (1) and fix it with the fixing bolt (15). Then, turn on the circulating cooling water system and turn on the vacuum pumping assembly to evacuate the vacuum distillation furnace body (1). When the pressure inside the vacuum distillation furnace body (1) reaches the set value, turn on the power and start heating the indium metal. The indium metal is ultra-high purity indium with a mass purity greater than 99.99999%. Step 2: After the vacuum pressure and the heating temperature of indium metal in the vacuum distillation furnace (1) in Step 1 reach the set values, keep the vacuum pressure and temperature constant and start vacuum distillation. During vacuum distillation, indium metal condenses on the metal partition (7) and the inner wall of the vacuum distillation furnace (1). Ultra-high purity indium balls are obtained on the metal partition (7) and the inner wall of the distillation condenser hood (4). Then, the ultra-high purity indium balls are sieved and stored.

2. The vacuum distillation apparatus for preparing ultra-high purity indium spheres according to claim 1, characterized in that, The vacuum distillation furnace body (1) and the cover plate (2) are fixed by bolts (15). The vacuum distillation furnace body (1) is provided with a vacuum channel (1-1), and the vacuum channel (1-1) is connected to a vacuum assembly. The vacuum distillation furnace body (1) is provided with a base (1-2) at the bottom.

3. The vacuum distillation apparatus for preparing ultra-high purity indium spheres according to claim 1, characterized in that, In the distillation condenser hood (4), multiple layers of metal partitions (7) are placed at equal intervals from bottom to top, with a layer spacing of 60mm to 100mm. The metal partitions (7) are supported by arc-shaped arch support seats (8) welded to the inner wall of the distillation condenser hood (4). The outer arc length of the arch of the support seat (8) is consistent with the outer arc length of the metal partition (7). The metal partition (7) consists of two double semi-circular plates with a thickness of 2mm to 3mm.

4. The vacuum distillation apparatus for preparing ultra-high purity indium spheres according to claim 1, characterized in that, The bottom support (8) is connected to the distillation condenser (4) by threads, and the bottom metal partition (7) is seamlessly connected to the riser (9). Holes and gaps are left between the metal partitions (7) of each of the remaining layers.

5. The vacuum distillation apparatus for preparing ultra-high purity indium spheres according to claim 1, characterized in that, The riser tube (9) has an inner diameter of 30mm~50mm and a height of 100mm~200mm. The riser tube (9) has multiple round holes, and the inner diameter of the small holes is 5mm~10mm. The riser tube (9) is made of boron nitride.

6. The vacuum distillation apparatus for preparing ultra-high purity indium spheres according to claim 1, characterized in that, The sleeve (11) has a height of 50mm~100mm and a thickness of 10mm~20mm. The aperture of the sleeve (11) is the same as the inner diameter of the graphite crucible (12). The sleeve (11) is made of alumina. The conical disk (10) is made of boron nitride. The angle between the side wall of the graphite crucible (12) and the horizontal plane is 85°~89°.

7. The vacuum distillation apparatus for preparing ultra-high purity indium spheres according to claim 1, characterized in that, The maximum loading capacity of the graphite crucible (12) shall not exceed 70% of its rated capacity.

8. The vacuum distillation apparatus for preparing ultra-high purity indium spheres according to claim 1, characterized in that, In step one, the pressure of the circulating cooling water is 0.15MPa~0.3MPa.

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