Vacuum distillation-zone melting impurity removal device and method for low-melting-point metal

Abstract

The invention discloses a low-melting-point metal vacuum distillation-zone melting impurity removal device, the interior of the device is divided into a vacuum distillation zone and a zone melting zone which are communicated, the vacuum distillation zone comprises a graphite crucible and a special-shaped condensation cover, the inner side wall of the special-shaped condensation cover is provided with a triangular airflow separator, and the inner bottom wall of the special-shaped condensation cover is provided with a plane airflow splitter plate; a bottom outlet is communicated with a flow guide pipe and is connected with a zone melting pipe of the zone melting zone through a flow guide branch pipe; the method comprises the steps that firstly, low-melting-point metal is added, and all parts are installed; 2, carrying out vacuum distillation on the low-melting-point metal; and 3, carrying out regional purification on the vacuum distillation material in the regional melting pipe. According to the device, the vacuum distillation zone and the zone melting zone which are communicated are arranged, so that zone melting impurity removal is directly carried out after low-melting-point metal is subjected to vacuum distillation impurity removal, and the defects of air oxidation, pollution introduction, long charging time and the like caused by segmented charging are overcome; the method enhances the impurity removal effect and is suitable for the field of metal purification.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal purification, and particularly relates to an apparatus and method for removing impurities from low-melting-point metals by vacuum distillation - zone melting. Background Art

[0002] High-purity rare and low-melting-point metals are one of the main raw materials for compound semiconductor manufacturing, and are mainly used in fields such as optical fiber communication technology, optical materials, and catalysts. In recent years, with the rapid development of the semiconductor industry, the domestic demand for high-purity low-melting-point metals has also increased accordingly. Currently, many high-purity low-melting-point metal purification technologies have become increasingly mature. Vacuum distillation technology, zone melting technology, single crystal pulling, electrolytic refining technology, and chemical reagent impurity removal technology are all beneficial to the purification of low-melting-point metals. In comparison, the purification effects of vacuum distillation technology, zone melting technology, and electrolytic refining technology are more obvious. Among them, vacuum distillation technology and zone refining technology belong to pyrometallurgy, while electrolytic refining technology belongs to hydrometallurgy. Pyrometallurgy has problems such as high energy consumption and serious pollution, while hydrometallurgy also has the problem that the waste acid solution generated during the electrolysis process is difficult to treat. Generally speaking, the pyrometallurgical purification efficiency of low-melting-point metals is higher.

[0003] Both vacuum distillation technology and zone melting technology can effectively remove impurity elements from low-melting-point metals. Vacuum distillation technology mainly uses the principle that in a vacuum environment, the impurity elements in the molten liquid of low-melting-point metals are separated from the main metal in a gas-liquid manner, ultimately achieving the purpose of purification. Zone melting technology mainly uses the principle that in a vacuum environment, the impurity elements with different equilibrium distribution coefficients in the molten liquid of low-melting-point metals are separated from the main metal in a solid-liquid manner, ultimately achieving the purpose of purification. Currently, both vacuum distillation technology and zone melting technology separately achieve the purification of low-melting-point metals, which directly leads to problems such as a long purification production process cycle and high labor costs. In addition, after the distilled material is taken out, it still needs to go through processes such as melting and forming, casting, and then can enter the next-stage zone melting process. However, there is a risk of introducing external pollution sources into the distilled material during this process. Therefore, these two methods still have certain limitations.

[0004] In view of the problems of long purification cycle, high labor cost, and introduction of external pollution sources caused by separately using vacuum distillation technology and zone melting technology to purify rare and low-melting-point metals at present, there is a need for an apparatus and method that can prepare a large amount of vacuum-distilled low-melting-point metals at one time, naturally cast and formed, and can be purified by zone melting. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a device for removing impurities by vacuum distillation - zone melting of low - melting - point metals in view of the deficiencies of the above - mentioned prior art. In this device, a connected vacuum distillation zone and zone melting zone are arranged inside the vacuum furnace body, so that the low - melting - point metals are evaporated and condensed in the special - shaped condensation cover for vacuum distillation to remove impurities, and then directly introduced into the zone melting zone for zone melting to remove impurities, realizing continuous impurity removal, enhancing the impurity - removal effect, improving the production efficiency of low - melting - point metal purification and the product quality, and solving the problems such as air oxidation caused by segmented feeding, pollution introduced by external transfer, and long charging time.

[0006] To solve the above - mentioned technical problems, the technical solution adopted by the present invention is: a device for removing impurities by vacuum distillation - zone melting of low - melting - point metals, which is characterized in that it includes a vacuum furnace body and a furnace door arranged on the side of the vacuum furnace body. A vacuum port is opened on the lower side of the vacuum furnace body, and the inside of the vacuum furnace body is divided into a connected vacuum distillation zone and zone melting zone by a partition board. The vacuum distillation zone includes a graphite crucible for containing low - melting - point metals and a special - shaped condensation cover installed on the opening of the graphite crucible. A first heater is arranged on the periphery of the graphite crucible. The top of the special - shaped condensation cover is pointed, a triangular air flow separator is arranged on the inner side wall near the opening of the graphite crucible, a planar air flow shunt plate is arranged at the connection of the inner bottom wall and the opening of the graphite crucible, and the triangular air flow separator and the planar air flow shunt plate are arranged opposite to each other. The bottom outlet of the special - shaped condensation cover is connected to a diversion pipe. The diversion pipe passes through the partition board and is connected to a zone melting pipe arranged in the zone melting zone through a diversion branch pipe. A second heater is movably arranged on the zone melting pipe.

[0007] The above - mentioned device for removing impurities by vacuum distillation - zone melting of low - melting - point metals is characterized in that the tip of the pointed top of the special - shaped condensation cover coincides with the central axis of the graphite crucible, and an auxiliary condensation system is arranged between the top of the special - shaped condensation cover and the zone melting zone. The bottom outlet of the special - shaped condensation cover adopts a downward - extending inclined overflow plate, and the angle between the inclined overflow plate and the horizontal line θ 3≥5°.

[0008] The above - mentioned device for removing impurities by vacuum distillation - zone melting of low - melting - point metals is characterized in that the bottom of the triangular air flow separator is installed on the inner side wall of the special - shaped condensation cover and can be freely adjusted in the vertical direction. The vertex of the triangular air flow separator coincides with the tip of the pointed top of the special - shaped condensation cover in the vertical direction, and the apex angle θ 1 satisfies: 5°≤ θ 1≤30°.

[0009] The above-described device for removing impurities from low-melting-point metals by vacuum distillation-zone melting is characterized in that one end of the planar air flow diverter is installed at the connection between the inner bottom wall of the special-shaped condensation cover and the opening of the graphite crucible, the other end can rotate freely around the end installation point, and the length of the planar air flow diverter is not less than the opening radius of the graphite crucible, and the angle between the planar air flow diverter and the horizontal line θ 2 satisfies: 0° ≤ θ 2 ≤ 90°.

[0010] The above-described device for removing impurities from low-melting-point metals by vacuum distillation-zone melting is characterized in that a base is installed at the bottom of the vacuum furnace body, and the vacuum furnace body is installed on a slideway. The graphite crucible is installed on a support platform, and a heat-insulating material is filled between the outer wall of the graphite crucible and the first heater.

[0011] Meanwhile, the present invention also discloses a method for removing impurities from low-melting-point metals by vacuum distillation-zone melting using the above-described device, which is characterized in that the method includes the following steps: Step 1: Add low-melting-point metal into the graphite crucible. Install one end of the planar air flow diverter at the connection between the bottom side wall of the special-shaped condensation cover and the opening of the graphite crucible, install the bottom of the triangular air flow separator on the inner side wall of the special-shaped condensation cover, then install the special-shaped condensation cover on the opening of the graphite crucible so that their horizontal planes are in close contact. Then connect the bottom outlet of the special-shaped condensation cover to the inlet of the diversion pipe, and connect the outlet of the diversion pipe to the zone melting pipes through diversion branch pipes respectively, and adjust the position of the second heater on the zone melting pipes. Step 2: Close the furnace door of the vacuum furnace body, turn on the vacuum pump to evacuate the inside of the vacuum furnace body through the vacuum port, and then turn on the first heater to heat and keep warm the low-melting-point metal in the graphite crucible until the vacuum distillation material enters the zone melting pipes through the diversion pipe and is filled. Step 3: Turn off the first heater to stop heating. After the vacuum distillation material in the diversion pipe solidifies, turn on the second heater to heat and keep warm the vacuum distillation material in the zone melting pipes, and then adjust the second heater to move reciprocally around the outer periphery of the zone melting pipes to perform zone purification on the heated vacuum distillation material to obtain high-purity low-melting-point metal.

[0012] The above-described method is characterized in that in Step 2, the vacuum evacuation is carried out until the vacuum pressure reaches 10 -3 Pa~10 - 1 Pa.

[0013] The above-described method is characterized in that in Step 2, the first heater heats the low-melting-point metal to 1000°C to 1200°C.

[0014] The above method is characterized in that in step three, the second heater heats the vacuum distillation material to 300°C to 500°C and keeps it warm for 10 minutes.

[0015] The above method is characterized in that in step three, the moving rate of the reciprocating movement of the second heater is 0.01 mm / min to 10 mm / min, and the number of reciprocating movements is 10 to 100. The present invention has the following advantages compared with the prior art: 1. In the device for vacuum distillation - zone melting purification of low - melting - point metals of the present invention, by arranging a connected vacuum distillation zone and a zone melting zone inside the vacuum furnace body, the vacuum distillation material obtained after the low - melting - point metals are evaporated and condensed in the special - shaped condensation cover for vacuum distillation and impurity removal is directly introduced into the zone melting zone for zone melting and impurity removal, realizing the process coupling of vacuum distillation and zone melting purification of low - melting - point metals, enhancing the impurity removal effect. At the same time, the low - melting - point metals after distillation and impurity removal in a vacuum environment directly enter the zone melting zone in a liquid state, avoiding the disadvantages such as air oxidation caused by segmented feeding, pollution introduced by external transfer, and long charging time, improving the production efficiency and product quality of low - melting - point metal purification.

[0016] 2. In the device for vacuum distillation - zone melting purification of low - melting - point metals of the present invention, a triangular gas - flow separator and a planar gas - flow shunt plate are arranged in the special - shaped condensation cover. By controlling their installation positions, distances, and angles, the flow direction and evaporation rate of the low - melting - point metal vapor flow are adjusted during the vacuum distillation process, thereby controlling the temperature - field distribution state inside the special - shaped condensation cover, promoting the progress of the vacuum distillation process, being beneficial to the distribution of different impurity elements in different regions of the condensation cover, greatly improving the vacuum distillation purification and impurity removal effect, and being particularly suitable for industrial production.

[0017] 3. The device for vacuum distillation - zone melting purification of low - melting - point metals of the present invention controls the structure of the special - shaped condensation cover, increasing the condensation area, being beneficial to quickly liquefying the evaporated low - melting - point metal vapor. At the same time, by arranging an outlet at the bottom of the special - shaped condensation cover to connect with the zone melting tube, it ensures that the low - melting - point metal liquid after vacuum distillation and impurity removal smoothly converges into the zone melting tube to continue zone melting and impurity removal, avoiding the problem of introducing new pollution sources during the process of taking the vacuum distillation material outside the furnace, and further improving the purification and impurity removal effect.

[0018] 4. The device for vacuum distillation - zone melting purification of low - melting - point metals of the present invention is provided with a second heater movably on the zone melting tube, facilitating the adjustment of the zone melting position and capable of simultaneously heating and melting and purifying the vacuum distillation materials in multiple zone melting tubes. By combining the control of the temperature, moving rate, and number of times of the second heater, it ensures that the vacuum distillation materials are fully purified, improving the purification and impurity removal effect of low - melting - point metals.

[0019] 5. The device for removing impurities from low-melting-point metals by vacuum distillation-zone melting according to the present invention is provided with a partitioned structure, combining the advantages of vacuum distillation technology and zone melting technology, shortening the purification cycle, improving production efficiency, and having a simple and compact device structure, which is easy to manufacture and obtain.

[0020] 6. In the method of the present invention, after the low-melting-point metal is vacuum distilled, the vapor flow of the low-melting-point metal is quickly condensed in the set direction by the gas flow separator in the special-shaped condensation cover, and then the obtained vacuum distillation material is introduced into the multi-station area for zone melting purification under the action of a heater, which not only improves the impurity removal effect, realizes continuous impurity removal, and is applicable to the industrial production of low-melting-point metals.

[0021] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Description of the Drawings

[0022] Figure 1 It is a schematic structural diagram of the device for removing impurities from low-melting-point metals by vacuum distillation-zone melting according to the present invention.

[0023] Description of the Reference Numerals in the Drawings Detailed Description of the Embodiment

[0024] The device for removing impurities from low-melting-point metals by vacuum distillation-zone melting in the present invention is described in detail through Embodiment 1.

[0025] Embodiment 1 The device for removing impurities from low-melting-point metals by vacuum distillation-zone melting in this embodiment includes a vacuum furnace body 1 and a furnace door 2 provided on the side of the vacuum furnace body 1. A vacuum port 14 is opened on the lower side of the vacuum furnace body 1, and the interior of the vacuum furnace body 1 is divided into a connected vacuum distillation area and a zone melting area by a partition 5. The vacuum distillation area includes a graphite crucible 9 for containing the low-melting-point metal 8 and a special-shaped condensation cover 3 installed on the opening of the graphite crucible 9. A first heater 7 is provided on the periphery of the graphite crucible 9. The top of the special-shaped condensation cover 3 is pointed, and a triangular gas flow separator 4 is provided on the inner side wall close to the opening of the graphite crucible 9. A flat gas flow diverter plate 6 is provided at the connection between the inner bottom wall and the opening of the graphite crucible 9, and the triangular gas flow separator 4 and the flat gas flow diverter plate 6 are arranged opposite to each other. The bottom outlet of the special-shaped condensation cover 3 is connected to a guide pipe 10. The guide pipe 10 passes through the partition 5 and is connected to a zone melting pipe 12 arranged in the zone melting area through a guide branch pipe 11. A second heater 13 is movably arranged on the zone melting pipe 12.

[0026] In the device for removing impurities by vacuum distillation - zone melting of low - melting - point metals in this embodiment, a vacuum furnace body 1 is provided as the place for vacuum distillation and zone melting for impurity removal. A furnace door 2 is opened on the side of the vacuum furnace body 1. The opening of the furnace door 2 facilitates the feeding of the low - melting - point metal 8 and the taking - out after impurity removal. By opening a vacuum port 14 on the lower side of the vacuum furnace body 1, it is used to connect equipment such as a vacuum pump to evacuate the internal cavity of the vacuum furnace body 1, continuously exhausting the air in the furnace body to provide a vacuum environment. In this embodiment, by arranging a partition plate 5 inside the vacuum furnace body 1, usually the partition plate 5 is arranged in the vertical direction, and a connecting channel is opened in the partition plate 5, dividing the interior of the vacuum furnace body 1 into two large connected areas - a vacuum distillation area and a zone melting area, which are respectively used as the places for vacuum distillation and zone melting for impurity removal of the low - melting - point metal. Specifically, a graphite crucible 9 is arranged in the vacuum distillation area to hold the low - melting - point metal 8. A first heater 7 is arranged on the periphery of the graphite crucible 9 to heat the low - melting - point metal 8 for vacuum distillation. An abnormal - shaped condenser cover 3 is installed on the opening of the graphite crucible 9 and connected to the graphite crucible 9 to form a vacuum distillation system. After the low - melting - point metal vapor flow formed by heating the low - melting - point metal 8 volatilizes into the abnormal - shaped condenser cover 3, it is condensed. By designing the top of the abnormal - shaped condenser cover 3 as a sharp angle, it is beneficial to increase the condensation area, extend the condensation path, and is conducive to the aggregation and dripping of the low - melting - point metal liquid formed by condensation. Usually, the internal size of the abnormal - shaped condenser cover 3 is larger than the opening size of the graphite crucible 9, which is beneficial to radiative heat dissipation and promotes the rapid condensation of the low - melting - point metal vapor flow. In this embodiment, a triangular gas flow separator 4 is arranged on the inner side wall of the abnormal - shaped condenser cover 3 close to the opening of the graphite crucible 9. On the one hand, it plays a role in blocking the low - melting - point metal vapor flow volatilizing into the abnormal - shaped condenser cover 3, reducing its flow rate. Thus, after the low - melting - point metal vapor flow continues to volatilize and bypasses the triangular gas flow separator 4, it condenses into droplets on the upper inner wall of the abnormal - shaped condenser cover 3, namely the vacuum distillation material, realizing the gas - liquid separation of the low - melting - point metal 8 and achieving vacuum distillation purification, avoiding the impurity elements in the low - melting - point metal 8 being mixed in the vacuum distillation material and affecting the purification effect of vacuum distillation. On the other hand, the triangular gas flow separator 4 plays a role in blocking the vacuum distillation material that condenses, aggregates, and drips, making it stay on the triangular gas flow separator 4, changing the path of the vacuum distillation material, and preventing it from dripping back into the graphite crucible 9 and losing the vacuum distillation purification effect.At the same time, the present embodiment sets a plane airflow diverter plate 6 at the connection between the inner bottom wall of the special-shaped condensation hood 3 and the opening of the graphite crucible 9, and the triangular airflow separator 4 is arranged opposite to the plane airflow diverter plate 6. On the one hand, it also plays a blocking role for the low-melting-point metal vapor flow, and blocks the radiation heat transfer from entering the condensation area of ​​the upper inner wall of the special-shaped condensation hood 3 to ensure the condensation effect. At the same time, it cooperates with the triangular airflow separator 4 to form a bending channel, control and change the movement direction of the low-melting-point metal vapor flow, extend its movement path, thereby changing the temperature field distribution in the special-shaped condensation hood 3, promoting the gas-liquid separation of the low-melting-point metal 8 after heating, and further improving the vacuum distillation purification effect. On the other hand, the plane airflow diverter plate 6 is used to receive the vacuum distillation material dripping from the condensation accumulation on the inner wall of the special-shaped condensation hood 3, and at the same time receive the vacuum distillation material staying on the triangular airflow separator 4, that is, by adjusting the relative position and angle relationship between the triangular airflow separator 4 and the plane airflow diverter plate 6, the vacuum distillation material staying on the triangular airflow separator 4 flows and drips onto the plane airflow diverter plate 6, and along the plane The air flow splitter 6 converges to the bottom outlet of the special-shaped condensation hood 3; in this embodiment, the bottom outlet of the special-shaped condensation hood 3 is connected to the guide pipe 10, and the guide pipe 10 passes through the partition 5 and is connected to the regional smelting pipe 12 arranged in the regional smelting area through the guide branch pipe 11, so that the vacuum distillation material enters the guide pipe 10, flows through the guide branch pipe 11, and enters the filling regional smelting pipe 12. Usually, one end of the regional smelting pipe 12 is connected to the guide branch pipe 11, and the other end is sealed. By movably arranging a second heater on the regional smelting pipe 12 13. The vacuum distillation material in the zone melting tube 12 is heated by the second heater 13 for zone melting and impurity removal, so that the vacuum distillation material of the purified product of the low melting point metal 8 after vacuum distillation in the vacuum distillation zone directly enters the zone melting zone for zone melting and impurity removal, realizing the coupling of vacuum distillation and zone melting and impurity removal processes, enhancing the impurity removal effect, eliminating the need for staged feeding, avoiding air oxidation, pollution introduced by external transfer, long loading time and other disadvantages, and improving the production efficiency and product quality of low melting point metal purification. ;

[0027] Typically, the guide pipe 10 in this embodiment passes through the partition 5 and is connected to a group of parallel guide branch pipes 11, and each parallel guide branch pipe 11 is respectively connected to each regional smelting pipe 12 one by one, forming a multi-station regional impurity removal system, which is beneficial to increase the processing capacity of vacuum distillation materials in the regional smelting area and improve the production efficiency of low-melting-point metal purification.

[0028] Generally, the melting point of the low melting point metal in the present invention does not exceed 500°C.

[0029] Furthermore, in this embodiment, the tip of the top sharp corner of the special-shaped condensation cover 3 coincides with the central axis of the graphite crucible 9, and an auxiliary condensation system is provided between the top of the special-shaped condensation cover 3 and the zone melting area. At the bottom outlet of the special-shaped condensation cover 3, a downward-extending inclined overflow plate is used, and the angle between the inclined overflow plate and the horizontal line θ 3 ≥ 5°. Since the radiative heat transfer at the central axis of the graphite crucible 9 is the most serious during the vacuum distillation process, in this embodiment, by setting the tip of the top sharp corner of the special-shaped condensation cover 3 to coincide with the central axis of the graphite crucible 9, it is ensured that the top sharp corner of the special-shaped condensation cover 3 is at the highest position, that is, the farthest from the graphite crucible 9, so that the temperature near the top sharp corner of the special-shaped condensation cover 3 is relatively low, which is beneficial for the low-melting-point metal vapor flow to rise and enter the low-temperature environment for rapid condensation; at the same time, by providing an auxiliary condensation system between the top of the special-shaped condensation cover 3 and the zone melting area, to promote the rapid condensation of the low-melting-point metal vapor flow to form the vacuum distillation material, especially to control the rapid condensation in the area between the top of the special-shaped condensation cover 3 and the zone melting area, reduce the mixing of the vacuum distillation material and the low-melting-point metal vapor flow volatilized from the graphite crucible 9, further improve the impurity removal effect, improve the production efficiency and product quality of the purification of low-melting-point metals, and achieve regional directional condensation; in addition, in this embodiment, at the bottom outlet of the special-shaped condensation cover 3, a downward-extending inclined overflow plate is used, and the angle between the inclined overflow plate and the horizontal line θ 3 ≥ 5° is controlled to ensure that the vacuum distillation material slowly discharges from the bottom outlet along the inclined overflow plate and smoothly enters the zone melting area. Usually, 5° ≤ θ 3 ≤ 10°.

[0030] Furthermore, in this embodiment, the bottom of the triangular gas flow separator 4 is installed on the inner side wall of the special-shaped condensation cover 3 and can be freely adjusted in the vertical direction. The vertex of the triangular gas flow separator 4 coincides with the tip of the top sharp corner of the special-shaped condensation cover 3 in the vertical direction, and the apex angle θ 1 satisfies: 5° ≤ θ 1 ≤ 30°. In this embodiment, by setting the bottom of the triangular gas flow separator 4 to be installed on the inner side wall of the special-shaped condensation cover 3, the installation stability of the triangular gas flow separator 4 is improved, and it can be freely adjusted in the vertical direction to control the height of the installation position of the triangular gas flow separator 4, change the flow rate of the low-melting-point metal vapor flow, and cooperate with the planar gas flow diverter 6 to change the movement direction of the low-melting-point metal vapor flow and the temperature field distribution in the special-shaped condensation cover 3, thereby controlling the gas-liquid separation effect of the low-melting-point metal vapor flow and ensuring the vacuum distillation purification effect; at the same time, in this embodiment, it is specified that the vertex of the triangular gas flow separator 4 coincides with the tip of the top sharp corner of the special-shaped condensation cover 3 in the vertical direction, ensuring that the vacuum distillation material that condenses and drips in the top sharp corner area of the special-shaped condensation cover 3 drops onto the triangular gas flow separator 4, and the apex angle θ1 is 5° to 30°, effectively controlling the oblique flow rate of the vacuum distillation material and enabling it to subsequently drip smoothly onto the planar gas flow diverter plate 6, avoiding its re-dripping onto the graphite crucible 9 and improving the efficiency of vacuum distillation purification.

[0031] Further, in this embodiment, one end of the planar gas flow diverter plate 6 is installed at the connection between the inner bottom wall of the special-shaped condensation cover 3 and the opening of the graphite crucible 9, and the other end can rotate freely around the end installation point. Moreover, the length of the planar gas flow diverter plate 6 is not less than the opening radius of the graphite crucible 9, and the angle θ 2 satisfies: 0° ≤ θ 2 ≤ 90°. In this embodiment, by setting one end of the planar gas flow diverter plate 6 at the connection between the special-shaped condensation cover 3 and the opening of the graphite crucible 9, and the other end can rotate freely around the end installation point, it is convenient to adjust the angle between the planar gas flow diverter plate 6 and the horizontal line. Usually, after adjusting and determining the angle, the connecting end of the planar gas flow diverter plate 6 is fixed to ensure structural stability. By controlling the angle θ 2 of the planar gas flow diverter plate 6 to be 0° to 90°, it is ensured that the vacuum distillation material received on the planar gas flow diverter plate 6 converges along the planar gas flow diverter plate 6 to the bottom outlet of the special-shaped condensation cover 3 and is discharged smoothly into the zone melting area.

[0032] Further, in this embodiment, a coating is provided on the inner wall of the zone melting tube 12. By providing a coating on the inner wall of the zone melting tube 12 in this embodiment, it is beneficial for the smooth demolding of the low-melting-point metal after vacuum distillation and zone melting for impurity removal.

[0033] Further, in this embodiment, the graphite crucible 9 is installed on the support table 15. By installing the graphite crucible 9 on the support table 15 in this embodiment, the stability of the graphite crucible 9 is improved, ensuring the smooth progress of the vacuum distillation process.

[0034] Further, in this embodiment, heat-insulating material 16 is filled between the outer wall of the graphite crucible 9 and the first heater 7. By filling heat-insulating material 16 between the outer wall of the graphite crucible 9 and the first heater 7 in this embodiment, heat loss is avoided, the heating effect of the first heater 7 on the graphite crucible 9 is enhanced, the temperature uniformity of the low-melting-point metal 8 in the graphite crucible 9 during vacuum distillation is improved, and the effect of vacuum distillation for impurity removal is improved.

[0035] Further, in this embodiment, a base 17 is installed at the bottom of the vacuum furnace body 1, and the vacuum furnace body 1 is installed on the slideway 18. By installing the base 17 at the bottom of the vacuum furnace body 1 in this embodiment, a good supporting and fixing effect is achieved on the vacuum furnace body 1. At the same time, by installing the vacuum furnace body 1 on the slideway 18, it is convenient to move the vacuum furnace body 1 to adapt to the requirements of different working scenarios.

[0036] Generally, the vacuum furnace body 1, the furnace door 2, and the partition plate 5 all adopt a double-layer stainless steel water-cooled structure; the special-shaped condensation cover 3 is made of high-purity graphite material with a mass purity of more than 99.995%; the triangular gas flow separator 4 is made of boron nitride material; the planar gas flow diverter plate 6 is made of boron nitride material or high-purity graphite material with a mass purity of more than 99.995%; the first heater 7 uses graphite heating or electromagnetic induction coil heating; the graphite crucible 9 is made of high-strength graphite material; the flow guide pipe 10 and the flow guide branch pipe 11 are made of high-purity graphite material with a mass purity of more than 99.995%; the second heater 13 uses resistance wire heating.

[0037] The method for removing impurities by vacuum distillation - zone melting of low-melting-point metals in the present invention is described in detail through Examples 2 to 9.

[0038] The low-melting-point metal 8 in Examples 1 to 9 of the present invention is indium metal.

[0039] Example 2 The method for removing impurities by vacuum distillation - zone melting of low-melting-point metals in this example includes the following steps: Step 1: Add 60 kg of solid low-melting-point metal 8 with 4N5 (mass percentage content of 99.995%) to the graphite crucible 9 as raw materials. Install one end of the planar gas flow diverter plate 6 at the connection between the bottom side wall of the special-shaped condensation cover 3 and the opening of the graphite crucible 9. Install the bottom of the triangular gas flow separator 4 on the inner side wall of the special-shaped condensation cover 3, and the distance from the lowest end of the triangular gas flow separator 4 to the opening of the graphite crucible 9 is 120 mm. Then install the special-shaped condensation cover 3 on the opening of the graphite crucible 9 so that their horizontal planes are in close contact. Then connect the bottom outlet of the special-shaped condensation cover 3 to the inlet of the flow guide pipe 10, and connect the outlet of the flow guide pipe 10 to the zone melting pipe 12 through the flow guide branch pipe 11 respectively, and adjust the position of the second heater 13 on the zone melting pipe 12; the apex angle θ 1 = 15°, the angle between the planar gas flow diverter plate 6 and the horizontal line θ 2 = 45°, the bottom outlet of the special-shaped condensation cover 3 is provided with a downward-extending inclined overflow plate, and the angle between the inclined overflow plate and the horizontal line θ 3 = 5°.

[0040] Step 2: Close the furnace door 2 of the vacuum furnace body 1, open the vacuum pump to evacuate the inside of the vacuum furnace body 1 through the vacuum port 14 until the vacuum pressure reaches 10 -3 Pa to 10 -1 Pa, and then turn on the first heater 7 to heat the low-melting-point metal 8 in the graphite crucible 9 to 1000 °C and keep it warm until the vacuum distillation material enters the zone melting pipe 12 through the flow guide pipe 10 and is filled up; Step 3: Turn off the first heater 7 to stop heating. After the vacuum distillation material in the diversion tube 10 solidifies, turn on the second heater 13 to heat the vacuum distillation material in the zone melting tube 12 to 300 °C and keep it warm for 10 min. Then, adjust the second heater 13 to move reciprocally around the outer periphery of the zone melting tube 12 at a moving rate of 0.1 mm / min and for 100 reciprocations to perform zone purification on the heated vacuum distillation material. After completion, turn off the second heater 13, open the furnace body, and take out the product in the zone melting tube 12 to obtain a high-purity low-melting-point metal.

[0041] Example 3 The method for removing impurities from a low-melting-point metal by vacuum distillation-zone melting in this example includes the following steps: Step 1: Add 60 kg of solid 4N5 (mass percentage content of 99.995%) low-melting-point metal 8 to the graphite crucible 9 as the raw material. Install one end of the planar air flow splitter 6 at the connection between the bottom side wall of the special-shaped condensation cover 3 and the opening of the graphite crucible 9. Install the bottom of the triangular air flow separator 4 on the inner side wall of the special-shaped condensation cover 3, and the distance from the lowermost end of the triangular air flow separator 4 to the opening of the graphite crucible 9 is 120 mm. Then, install the special-shaped condensation cover 3 on the opening of the graphite crucible 9 so that their horizontal planes are in close contact. Then, connect the bottom outlet of the special-shaped condensation cover 3 to the inlet of the diversion tube 10, and connect the outlet of the diversion tube 10 to the zone melting tube 12 through the diversion branch pipe 11, and adjust the position of the second heater 13 on the zone melting tube 12; the apex angle θ 1 = 15°, the included angle between the planar air flow splitter 6 and the horizontal line θ 2 = 45°, the bottom outlet of the special-shaped condensation cover 3 is provided with a downward-extending inclined overflow plate, and the included angle between the inclined overflow plate and the horizontal line θ 3 = 5°; Step 2: Close the furnace door 2 of the vacuum furnace body 1, turn on the vacuum pump to evacuate the inside of the vacuum furnace body 1 through the vacuum port 14 until the vacuum pressure reaches 10 -3 Pa~10 -1 Pa, and then turn on the first heater 7 to heat the low-melting-point metal 8 in the graphite crucible 9 to 1100 °C and keep it warm until the vacuum distillation material enters the zone melting tube 12 through the diversion tube 10 and is full; Step 3: Turn off the first heater 7 to stop heating. After the vacuum distillation material in the diversion tube 10 solidifies, turn on the second heater 13 to heat the vacuum distillation material in the zone melting tube 12 to 400 °C and keep it warm for 10 min. Then adjust the second heater 13 to move reciprocally on the outer periphery of the zone melting tube 12 at a moving rate of 0.1 mm / min and for 100 reciprocating times to perform zone purification on the heated vacuum distillation material. After completion, turn off the second heater 13, open the furnace body, and take out the product in the zone melting tube 12 to obtain high-purity low-melting-point metal.

[0042] Example 4 The method for removing impurities from low-melting-point metal by vacuum distillation-zone melting in this example includes the following steps: Step 1: Add 60 kg of solid 4N5 (mass percentage content of 99.995%) low-melting-point metal 8 into the graphite crucible 9 as raw material. Install one end of the planar air flow splitter 6 at the connection between the bottom side wall of the special-shaped condensation cover 3 and the opening of the graphite crucible 9. Install the bottom of the triangular air flow separator 4 on the inner side wall of the special-shaped condensation cover 3, and the distance from the lowermost end of the triangular air flow separator 4 to the opening of the graphite crucible 9 is 120 mm. Then install the special-shaped condensation cover 3 on the opening of the graphite crucible 9 so that their horizontal planes are in close contact. Then connect the bottom outlet of the special-shaped condensation cover 3 to the inlet of the diversion tube 10, connect the outlet of the diversion tube 10 to the zone melting tube 12 through the diversion branch pipe 11 respectively, and adjust the position of the second heater 13 on the zone melting tube 12; the apex angle θ 1 = 15°, the angle between the planar air flow splitter 6 and the horizontal line θ 2 = 45°, the bottom outlet of the special-shaped condensation cover 3 is provided with a downward-extending inclined overflow plate, and the angle between the inclined overflow plate and the horizontal line θ 3 = 5°; Step 2: Close the furnace door 2 of the vacuum furnace body 1, turn on the vacuum pump to evacuate the inside of the vacuum furnace body 1 through the vacuum port 14 until the vacuum pressure reaches 10 -3 Pa to 10 -1 Pa, and then turn on the first heater 7 to heat the low-melting-point metal 8 in the graphite crucible 9 to 1100 °C and keep it warm until the vacuum distillation material enters the zone melting tube 12 through the diversion tube 10 and is filled; Step 3: Turn off the first heater 7 to stop heating. After the vacuum distillation material in the diversion pipe 10 solidifies, turn on the second heater 13 to heat the vacuum distillation material in the zone melting pipe 12 to 500 °C and keep it warm for 10 min. Then adjust the second heater 13 to move reciprocally around the outer periphery of the zone melting pipe 12 at a moving rate of 0.1 mm / min and with 100 reciprocating movements to conduct zone purification on the heated vacuum distillation material. After completion, turn off the second heater 13, open the furnace body, and take out the product in the zone melting pipe 12 to obtain high-purity low-melting-point metal.

[0043] Example 5 The method for removing impurities from low-melting-point metal by vacuum distillation-zone melting in this example includes the following steps: Step 1: Add 60 kg of solid 4N5 (mass percentage content of 99.995%) low-melting-point metal 8 into the graphite crucible 9 as raw material. Install one end of the planar air flow splitter 6 at the connection between the bottom side wall of the special-shaped condensation cover 3 and the opening of the graphite crucible 9. Install the bottom of the triangular air flow separator 4 on the inner side wall of the special-shaped condensation cover 3, and the distance from the lowermost end of the triangular air flow separator 4 to the opening of the graphite crucible 9 is 120 mm. Then install the special-shaped condensation cover 3 on the opening of the graphite crucible 9 so that their horizontal planes are in close contact. Then connect the bottom outlet of the special-shaped condensation cover 3 to the inlet of the diversion pipe 10, and connect the outlet of the diversion pipe 10 to the zone melting pipe 12 through the diversion branch pipe 11 respectively, and adjust the position of the second heater 13 on the zone melting pipe 12; the apex angle θ 1 = 15°, the included angle between the planar air flow splitter 6 and the horizontal line θ 2 = 45°, the bottom outlet of the special-shaped condensation cover 3 is provided with a downward-extending inclined overflow plate, and the included angle between the inclined overflow plate and the horizontal line θ 3 = 5°; Step 2: Close the furnace door 2 of the vacuum furnace body 1, turn on the vacuum pump to evacuate the inside of the vacuum furnace body 1 through the vacuum port 14 until the vacuum pressure reaches 10 -3 Pa~10 -1 Pa, and then turn on the first heater 7 to heat the low-melting-point metal 8 in the graphite crucible 9 to 1200 °C and keep it warm until the vacuum distillation material enters the zone melting pipe 12 through the diversion pipe 10 and is filled up; Step 3: Turn off the first heater 7 to stop heating. After the vacuum distillation material in the diversion pipe 10 solidifies, turn on the second heater 13 to heat the vacuum distillation material in the zone melting tube 12 to 400 °C and keep it warm for 10 min. Then adjust the second heater 13 to move reciprocally on the outer periphery of the zone melting tube 12 at a moving rate of 0.1 mm / min and with 100 reciprocating movements to perform zone purification on the heated vacuum distillation material. After completion, turn off the second heater 13, open the furnace body, and take out the product in the zone melting tube 12 to obtain a high-purity low-melting-point metal.

[0044] Example 6 The method for removing impurities from a low-melting-point metal by vacuum distillation-zone melting in this example includes the following steps: Step 1: Add 60 kg of solid 4N5 (mass percentage content of 99.995%) low-melting-point metal 8 into the graphite crucible 9 as the raw material. Install one end of the planar air flow splitter 6 at the connection between the bottom side wall of the special-shaped condensation cover 3 and the opening of the graphite crucible 9. Install the bottom of the triangular air flow separator 4 on the inner side wall of the special-shaped condensation cover 3, and the distance from the lowermost end of the triangular air flow separator 4 to the opening of the graphite crucible 9 is 120 mm. Then install the special-shaped condensation cover 3 on the opening of the graphite crucible 9 so that their horizontal planes are in close contact. Then connect the bottom outlet of the special-shaped condensation cover 3 to the inlet of the diversion pipe 10, and connect the outlet of the diversion pipe 10 to the zone melting tube 12 through the diversion branch pipe 11 respectively, and adjust the position of the second heater 13 on the zone melting tube 12; the apex angle θ 1 = 15°, the included angle between the planar air flow splitter 6 and the horizontal line θ 2 = 45°, and at the bottom outlet of the special-shaped condensation cover 3, a downward-extending inclined overflow plate is used, and the included angle between the inclined overflow plate and the horizontal line θ 3 = 5°; Step 2: Close the furnace door 2 of the vacuum furnace body 1, turn on the vacuum pump to evacuate the inside of the vacuum furnace body 1 through the vacuum port 14 until the vacuum pressure reaches 10 -3 Pa~10 -1 Pa, and then turn on the first heater 7 to heat the low-melting-point metal 8 in the graphite crucible 9 to 1200 °C and keep it warm until the vacuum distillation material enters the zone melting tube 12 through the diversion pipe 10 and is filled; Step 3: Turn off the first heater 7 to stop heating. After the vacuum distillation material in the diversion tube 10 solidifies, turn on the second heater 13 to heat the vacuum distillation material in the zone melting tube 12 to 300 °C and keep it warm for 10 min. Then adjust the second heater 13 to move reciprocally on the outer periphery of the zone melting tube 12 at a moving rate of 0.1 mm / min and with 100 reciprocating movements to perform zone purification on the heated vacuum distillation material. After completion, turn off the second heater 13, open the furnace body, and take out the product in the zone melting tube 12 to obtain high-purity low-melting-point metal.

[0045] Example 7 The method for removing impurities from low-melting-point metal by vacuum distillation-zone melting in this example includes the following steps: Step 1: Add 60 kg of solid 4N5 (mass percentage content of 99.995%) low-melting-point metal 8 into the graphite crucible 9 as raw material. Install one end of the planar air flow diverter plate 6 at the connection between the bottom side wall of the special-shaped condensation cover 3 and the opening of the graphite crucible 9. Install the bottom of the triangular air flow separator 4 on the inner side wall of the special-shaped condensation cover 3, and the distance from the lowermost end of the triangular air flow separator 4 to the opening of the graphite crucible 9 is 120 mm. Then install the special-shaped condensation cover 3 on the opening of the graphite crucible 9 so that their horizontal planes are in close contact. Then connect the bottom outlet of the special-shaped condensation cover 3 to the inlet of the diversion tube 10, and connect the outlet of the diversion tube 10 to the zone melting tube 12 through the diversion branch pipe 11 respectively, and adjust the position of the second heater 13 on the zone melting tube 12; the apex angle θ 1 = 15°, the included angle between the planar air flow diverter plate 6 and the horizontal line θ 2 = 45°, and the bottom outlet of the special-shaped condensation cover 3 is provided with a downward-extending inclined overflow plate, and the included angle between the inclined overflow plate and the horizontal line θ 3 = 5°; Step 2: Close the furnace door 2 of the vacuum furnace body 1, turn on the vacuum pump to evacuate the inside of the vacuum furnace body 1 through the vacuum port 14 until the vacuum pressure reaches 10 -3 Pa~10 -1 Pa, and then turn on the first heater 7 to heat the low-melting-point metal 8 in the graphite crucible 9 to 1200 °C and keep it warm until the vacuum distillation material enters the zone melting tube 12 through the diversion tube 10 and is filled; Step 3: Turn off the first heater 7 to stop heating. After the vacuum distillation material in the diversion tube 10 solidifies, turn on the second heater 13 to heat the vacuum distillation material in the zone melting tube 12 to 500 °C and keep it warm for 10 min. Then, adjust the second heater 13 to move reciprocally around the outer periphery of the zone melting tube 12 at a moving rate of 0.1 mm / min and for 100 reciprocations to perform zone purification on the heated vacuum distillation material. After completion, turn off the second heater 13, open the furnace body, and take out the product in the zone melting tube 12 to obtain high-purity low-melting-point metal.

[0046] The chemical compositions of the low-melting-point metal raw materials used in Examples 2 to 7 of the present invention and the obtained high-purity low-melting-point metal were inspected, and the results are shown in Table 1.

[0047] Table 1

[0048] As can be seen from Table 1, the contents of impurity elements in the low-melting-point metals in Examples 2 to 7 of the present invention were significantly lower than those of the raw materials, indicating that the vacuum distillation - zone melting impurity removal method of the present invention has excellent impurity removal effects on low-melting-point metals.

[0049] Example 8 The difference between this example and Example 2 is that: in Step 1, the apex angle θ 1 = 5° of the triangular air flow separator 4, the included angle θ 2 = 90° between the planar air flow diverter plate 6 and the horizontal line, and the bottom outlet of the special-shaped condensation cover 3 is provided with a downward-extending inclined overflow plate, and the included angle θ 3 = 10° between the inclined overflow plate and the horizontal line; in Step 3, adjust the second heater 13 to move reciprocally around the outer periphery of the zone melting tube 12 at a moving rate of 0.01 mm / min and for 10 reciprocations.

[0050] Example 9 The difference between this example and Example 2 is that: in Step 1, the apex angle θ 1 = 30° of the triangular air flow separator 4, the included angle θ 2 = 0° between the planar air flow diverter plate 6 and the horizontal line, and the bottom outlet of the special-shaped condensation cover 3 is provided with a downward-extending inclined overflow plate, and the included angle θ 3 = 5° between the inclined overflow plate and the horizontal line; in Step 3, adjust the second heater 13 to move reciprocally around the outer periphery of the zone melting tube 12 at a moving rate of 10 mm / min and for 50 reciprocations.

[0051] After detection, the contents of impurity elements in the low-melting-point metals in Examples 8 to 9 of the present invention were also significantly lower than those of the raw materials, indicating that the vacuum distillation - zone melting impurity removal method of the present invention has excellent impurity removal effects on low-melting-point metals.

[0052] The above are only the preferred embodiments of the present invention and do not impose any limitations on the present invention. Any simple modifications, changes, and equivalent variations made to the above embodiments based on the technical essence of the invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A device for removing impurities by vacuum distillation - zone melting of low - melting - point metals, characterized in that, It includes a vacuum furnace body (1) and a furnace door (2) arranged on the side of the vacuum furnace body (1). A vacuum port (14) is opened on the lower side of the vacuum furnace body (1), and the interior of the vacuum furnace body (1) is divided into a connected vacuum distillation area and a zone melting area by a partition plate (5). The vacuum distillation area includes a graphite crucible (9) for containing a low-melting-point metal (8) and a special-shaped condensation cover (3) installed on the opening of the graphite crucible (9). A first heater (7) is arranged on the peripheral side of the graphite crucible (9). The top of the special-shaped condensation cover (3) is pointed. A triangular air flow separator (4) is arranged on the inner side wall close to the opening of the graphite crucible (9). A flat air flow diverter plate (6) is arranged at the connection between the inner bottom wall and the opening of the graphite crucible (9), and the triangular air flow separator (4) and the flat air flow diverter plate (6) are arranged opposite to each other. The bottom outlet of the special-shaped condensation cover (3) is connected to a guide pipe (10). The guide pipe (10) passes through the partition plate (5) and is connected to a zone melting pipe (12) arranged in the zone melting area through a guide branch pipe (11). A second heater (13) is movably arranged on the zone melting pipe (12).

2. The device for removing impurities by vacuum distillation - zone melting of low - melting - point metals according to claim 1, characterized in that, The apex of the top sharp corner of the special-shaped condensation cover (3) coincides with the central axis of the graphite crucible (9), and an auxiliary condensation system is provided between the top of the special-shaped condensation cover (3) and the zone melting area. The bottom outlet of the special-shaped condensation cover (3) is provided with a downward-extending inclined overflow plate, and the angle between the inclined overflow plate and the horizontal line θ is not less than 5°.

3. The device for removing impurities by low melting point metal vacuum distillation - zone melting according to claim 1, characterized in that, The bottom of the triangular air flow separator (4) is installed on the inner side wall of the special-shaped condensation cover (3) and can be freely adjusted in the vertical direction. The vertex of the triangular air flow separator (4) coincides with the apex of the top sharp angle of the special-shaped condensation cover (3) in the vertical direction, and the apex angle of the triangular air flow separator (4) θ 1 satisfies: 5° ≤ θ 1 ≤ 30°.

4. A device for removing impurities by vacuum distillation - zone melting of a low - melting - point metal according to claim 1, characterized in that, One end of the planar air flow diverter plate (6) is installed at the connection between the inner bottom wall of the special-shaped condensation cover (3) and the opening of the graphite crucible (9), and the other end can freely rotate around the end installation point. The length of the planar air flow diverter plate (6) is not less than the opening radius of the graphite crucible (9), and the angle between the planar air flow diverter plate (6) and the horizontal line θ 2 satisfies: 0° ≤ θ 2 ≤ 90°.

5. The device for removing impurities by vacuum distillation - zone melting of low - melting - point metals according to claim 1, characterized in that, A base (17) is installed at the bottom of the vacuum furnace body (1), and the vacuum furnace body (1) is installed on a slideway (18). The graphite crucible (9) is installed on a support platform (15), and a heat-insulating material (16) is filled between the outer wall of the graphite crucible (9) and the first heater (7).

6. A method for removing impurities from low-melting metals by vacuum distillation-zone melting using the device according to any one of claims 1 to 5, characterized in that, The method includes the following steps: Step 1: Add a solid low-melting-point metal (8) into the graphite crucible (9). Install one end of the flat air flow diverter plate (6) at the connection between the bottom side wall of the special-shaped condensation cover (3) and the opening of the graphite crucible (9). Install the bottom of the triangular air flow separator (4) on the inner side wall of the special-shaped condensation cover (3). Then install the special-shaped condensation cover (3) on the opening of the graphite crucible (9) so that their horizontal planes are in close contact. Then connect the bottom outlet of the special-shaped condensation cover (3) to the inlet of the guide pipe (10). Connect the outlet of the guide pipe (10) to the zone melting pipe (12) through the guide branch pipe (11) respectively, and adjust the position of the second heater (13) on the zone melting pipe (12). Step 2: Close the furnace door (2) of the vacuum furnace body 1. Open the vacuum pump to evacuate the interior of the vacuum furnace body (1) through the vacuum port (14). Then turn on the first heater (7) to heat and keep warm the low-melting-point metal (8) in the graphite crucible (9) until the vacuum distillation material enters the zone melting pipe (12) through the guide pipe (10) and is filled up. Step 3: Turn off the first heater (7) to stop heating. After the vacuum distillation material in the guide pipe (10) solidifies, turn on the second heater (13) to heat and keep warm the vacuum distillation material in the zone melting pipe (12). Then adjust the second heater (13) to move reciprocally on the outer periphery of the zone melting pipe (12) to perform zone purification on the heated vacuum distillation material to obtain a high-purity low-melting-point metal.

7. The method according to claim 6, wherein In Step 2, evacuate until the vacuum pressure reaches 10 -3 Pa~10 -1 Pa.

8. The method according to claim 6, characterized in that In step two, the first heater (7) heats the low melting point metal (8) to 1000°C to 1200°C.

9. The method according to claim 6, wherein In step three, the second heater (13) heats the vacuum distillation material to 300°C to 500°C and holds for 10 minutes.

10. The method according to claim 6, wherein In step three, the moving rate of the reciprocating motion of the second heater (13) is 0.01 mm / min to 10 mm / min, and the number of reciprocating motions is 10 to 100.

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