Device and method for preparing high-purity selenium dioxide

Abstract

The invention provides a device and a method for preparing high-purity selenium dioxide, which can effectively remove impurities which have large difference in saturation solubility with selenium dioxide solid phase in liquid phases such as water, ethanol and the like, and realize preparation of high-purity selenium dioxide. According to the invention, a dissolution crystallization method and a similar zone melting mechanism for melting crystallization are unified and expanded to most dissolvable compounds. The device and the method provided by the invention have the advantages of high purity upper limit, low energy consumption, strong applicability and the like.

Description

Technical Field

[0001] This application relates to the field of metal purification technology, and more specifically, to an apparatus and method for preparing high-purity selenium dioxide. Background Technology

[0002] High-purity selenium dioxide, as an important scientific research and industrial raw material, can be used to prepare high-purity selenium or directly applied in fields such as thin-film solar cells, infrared detectors, and high-end medical devices. The purification of selenium dioxide is the core challenge in the preparation of high-purity selenium and also represents the current development direction in this field. Achieving the preparation of high-purity selenium dioxide is crucial for the development of the entire high-purity selenium-related field.

[0003] Currently, the dissolution-crystallization method is commonly used for the purification of selenium dioxide. However, this method not only has low crystallization efficiency and limited purification effect per cycle, but also requires repeated dissolution, crystallization, and filtration operations to remove tellurium, an impurity with similar properties to selenium, when preparing high-purity selenium dioxide of 6N (99.9999 wt%) and above. The overall process is cumbersome, and it is difficult to further improve the purity. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides an apparatus and method for preparing high-purity selenium dioxide, which can effectively remove impurities with significantly different saturated solubility in liquid phases such as water and ethanol compared to the solid phase of selenium dioxide, thereby achieving the preparation of high-purity selenium dioxide. This invention unifies the dissolution crystallization method and the melt crystallization method using a mechanism similar to zone melting, extending it to most soluble compounds. The apparatus and method provided by this invention have advantages such as high purity upper limit, low energy consumption, and strong applicability.

[0005] In a first aspect, the present invention provides an apparatus for preparing high-purity selenium dioxide, comprising: Crucible (1), heating device (2) and dripping device (3); The crucible (1) is capable of sliding relative to the heating device (2) in a first direction; The heating device (2) includes at least one heater (21); The dripping device (3) is located on the side of the crucible (1) away from the heating device (2); The crucible (1) is filled with crude selenium dioxide. During the process of the crucible (1) sliding along the first direction, the dripping device (3) is configured to drip solvent onto the crucible (1) to dissolve the crude selenium dioxide and obtain a solid-liquid mixture. The heating device (2) is configured to heat the solid-liquid mixture in the crucible (1) to evaporate and recrystallize it to obtain high-purity selenium dioxide.

[0006] Optionally, the device further includes a sliding device (4). The sliding device (4) includes a first pulley (41) and a second pulley (42); In the first direction, the first pulley (41) and the second pulley (42) are respectively connected to both ends of the crucible (1), and the heating device (2) is located between the first pulley (41) and the second pulley (42); The crucible (1) moves along the first direction under the drive of the sliding device (4).

[0007] Optionally, the crucible (1) includes a pot body (11), a first external part (12), and a second external part (13). The pot body (11) is filled with the crude selenium dioxide product; the first external part (12) and the second external part (13) are respectively connected to the opposite ends of the pot body (11); The first pulley (41) is connected to the first external part (12), and the second pulley (42) is connected to the second external part (13); The crucible (1) slides along the first external part (12) toward the second external part (13).

[0008] Optionally, the heater (21) is wrapped around the outer wall of the crucible (1).

[0009] Optionally, the dripping device (3) includes at least one dripper (31). The heater (21) includes at least one heating zone (211) and a transition zone (212); The dropper (31) and the transition zone (212) are respectively arranged in a second direction perpendicular to the first direction; The temperature of the heating zone is higher than the temperature of the transition zone.

[0010] Optionally, the heater (21) includes a plurality of heating zones (211) and at least one transition zone (212). The plurality of heating zones (211) and at least one transition zone (212) are arranged in the first direction.

[0011] Optionally, the heating device (2) includes a plurality of heaters, and the heating zone (211) and the transition zone (212) formed by the plurality of heaters are alternately arranged in the first direction.

[0012] Optionally, the heating device (2) includes a plurality of the heaters (21); In the first direction, the distance between two adjacent heaters (21) is 10mm-300mm.

[0013] In a second aspect, the present invention provides a method for preparing high-purity selenium dioxide, the method being applicable to the apparatus for preparing high-purity selenium dioxide described in the first aspect above; the method comprising: The crude selenium dioxide product is loaded into the crucible, the heating device is turned on, and the crucible is slid along the first direction. The heating device heats the crucible to 80℃-300℃. The dripping device is activated, and solvent is added dropwise to the crucible area that slides into the heating device to dissolve the crude selenium dioxide and obtain a solid-liquid mixture. Under the heat provided by the heating device, the solid-liquid mixture evaporates, causing the crude selenium dioxide to recrystallize and precipitate high-purity selenium dioxide crystals. The solvent is selected from water, ethanol, ammonia, and hydrochloric acid. The crucible moves at a speed of 0.25 mm / min to 3 mm / min. The dripping rate of the dripping device is 0.3 ml / min to 3.6 ml / min.

[0014] Optionally, the preparation method further includes: The crude selenium dioxide product is recycled 2-10 times for recrystallization; Specifically, the crucible's moving speed is greater during odd-numbered recrystallization processes than during even-numbered recrystallization processes; and the dropping speed of the dropping device is greater during odd-numbered recrystallization processes than during even-numbered recrystallization processes.

[0015] In summary, the present invention has at least one of the following beneficial technical effects: 1. This invention provides an apparatus for preparing high-purity selenium dioxide. By creating relative sliding between the crucible filled with crude selenium dioxide and the heating device, and by adding solvent dropwise at specific locations, the dissolution and recrystallization processes are integrated into a continuous dynamic process, significantly improving crystallization efficiency. The apparatus provided by this invention utilizes the principles of zoned heating and directional crystallization, achieving highly efficient regional purification in a single operation, effectively overcoming the cumbersome problem of traditional methods requiring multiple repetitions of dissolution, crystallization, and filtration. Especially for removing tellurium, an impurity with similar properties to selenium, the apparatus provided by this invention can better utilize the segregation effect to selectively separate impurities by controlling the movement rate and temperature gradient of the crystallization front, thereby breaking through the bottleneck of purity improvement in traditional methods and providing a more efficient and reliable solution for preparing 6N and higher purity selenium dioxide.

[0016] 2. This invention provides a method for preparing high-purity selenium dioxide. By heating crude selenium dioxide at a temperature of 80℃-300℃ and controlling the crucible to slide at a specific speed of 0.25mm / min to 3mm / min while simultaneously adding solvent dropwise at a rate of 0.3ml / min to 3.6ml / min, the dissolution, evaporation, and recrystallization processes are integrated into a continuous and controllable directional zone melting process, significantly improving the crystallization efficiency and purification effect of a single operation. The preparation method provided by this invention can efficiently separate tellurium and other impurities with similar properties to selenium in a continuous process, effectively avoiding the cumbersome operations of repeated dissolution, crystallization, and filtration in traditional methods, and overcoming the purity bottleneck caused by multiple purification processes. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A structural diagram of the apparatus for preparing high-purity selenium dioxide provided in an embodiment of the present invention is shown; Figure 2 A top view of the crucible and heating device provided in an embodiment of the present invention is shown; Figure 3 The three-view diagram of the crucible provided in the embodiment of the present invention is shown; Figure 4 The three-view diagram of the heater provided in the embodiment of the present invention is shown; Figure 5 A flowchart of the preparation method of high-purity selenium dioxide provided in an embodiment of the present invention is shown.

[0019] Figure label: 1. Crucible; 11. Pot body; 12. First external connection part; 13. Second external connection part; 2. Heating device; 21. Heater; 211. Heating zone; 212. Transition zone; 3. Dropping device; 31. Dropper; 4. Sliding device; 41. First pulley; 42. Second pulley; 5. Support platform. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention. Furthermore, all other embodiments obtained by those skilled in the art without inventive effort are within the protection scope of the present invention.

[0021] Specific experimental steps or conditions are not specified in the embodiments; they can be performed according to the conventional experimental steps or conditions described in the prior art. Reagents and other instruments used, unless otherwise specified, are all commercially available conventional reagent products. Furthermore, the accompanying drawings are merely illustrative diagrams of the embodiments of the present invention and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore, repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0022] Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of this specification.

[0023] In the description of this invention, it should be understood that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0024] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0025] In related technologies, high-purity selenium dioxide serves as an important research and industrial raw material, used in the preparation of high-purity selenium or directly applied in fields such as thin-film solar cells, infrared detectors, and high-end medical devices. The purification of selenium dioxide is the core challenge in the preparation of high-purity selenium and also represents the current development direction for high-purity selenium production. Achieving the preparation of high-purity selenium dioxide is crucial for the development of the entire high-purity selenium-related field.

[0026] Currently, the dissolution-crystallization method is commonly used for selenium dioxide purification. However, this method suffers from low direct crystallization efficiency and limited purification effect in a single step. To effectively remove impurities such as tellurium to prepare high-purity selenium dioxide of 6N (99.9999 wt%) and above, multiple repeated dissolution, crystallization, and filtration operations are often required, and the purification effect is difficult to further improve. Zone melting is well known to be an important method for preparing high-purity metals of 7N (99.99999 wt%) and above, but because the partition coefficient of most impurities in selenium is close to 1, this process is difficult to achieve the preparation of high-purity selenium of 7N and above.

[0027] To address the problems existing in related technologies, this invention proposes a step-by-step zone dissolution method. While the mechanism still falls under the category of crystallization purification, its purification concept is closer to zone melting and can be considered a type of "zone melting-like" process. Using the step-by-step zone dissolution method, not only can high-purity selenium dioxide of 7N and above be prepared, but it can also be extended to the purification process of various soluble-crystallizable compounds. The partition coefficient, at a certain temperature, is the ratio of the concentration of impurities in the solid phase to their concentration in the liquid phase, and is a key parameter for measuring the effectiveness of zone purification; if the partition coefficient is close to 1, the impurities are difficult to separate through zone melting. Segregation effect, during crystallization, is the phenomenon where the different solubilities of impurities in the solid and liquid phases cause impurities to be repelled into the liquid phase or enriched in the solid phase, which is the basic principle for achieving purification.

[0028] Specifically, embodiments of the present invention provide an apparatus for preparing high-purity selenium dioxide, such as... Figure 1 As shown, it includes: Crucible 1, heating device 2, and dripping device 3; The crucible 1 is capable of sliding relative to the heating device 2 in a first direction; The heating device 2 includes at least one heater 21; The dripping device 3 is located on the side of the crucible 1 away from the heating device 2; The crucible 1 is filled with crude selenium dioxide. As the crucible 1 slides along the first direction, the dripping device 3 is configured to drip solvent onto the crucible 1 to dissolve the crude selenium dioxide and obtain a solid-liquid mixture. The heating device 2 is configured to heat the solid-liquid mixture in the crucible 1 to evaporate and recrystallize it to obtain high-purity selenium dioxide.

[0029] It should be noted that, as Figure 1 As shown, the crucible 1 can be strip-shaped; the material of crucible 1 can be quartz. The first direction is Figure 1 The OX direction is shown; like Figure 1 and Figure 2As shown, crucible 1 passes through heating device 2 along the OX direction, and crucible 1 can slide horizontally within heating device 2 along the OX direction; the opening of crucible 1 is located on the side away from heating device 2. The crucible 1 moves at a speed of 0.25 mm / min to 3 mm / min in the OX direction; for example, the crucible 1 moves at a speed of 0.25 mm / min, 0.5 mm / min, 1 mm / min, 1.5 mm / min, 2 mm / min, 2.5 mm / min, and 3 mm / min in the OX direction. Heating device 2 is a type of heater 21 that can provide sufficient heat to the sliding crucible 1; The dripping device 3 is a type of dripping equipment that can control the dripping speed, is corrosion resistant, and does not react with the solvent; The dripping rate of the dripping device 3 is 0.3 ml / min to 3.6 ml / min; for example, the dripping rate of the dripping device 3 is 0.3 ml / min, 1.5 ml / min, 2 ml / min, 2.5 ml / min, 3 ml / min, 3.3 ml / min, and 3.6 ml / min. The side of crucible 1 facing away from heating device 2 indicates that: in such a situation... Figure 1 In the OY direction shown, the dripping device 3 is located above the crucible 1 to facilitate the downward dripping of solvent into the crucible 1 area that slides into the heating device 2; In some embodiments, such as Figure 1 As shown, the device also includes a support platform 5; The dimension of support platform 5 in the OX direction is larger than its dimension in the OY direction; The heater 21 is fixedly connected to the support platform 5 on the side away from the crucible 1.

[0030] In some embodiments, since selenium dioxide is toxic, the entire device is housed in a glass chamber equipped with a ventilation system and a selenium dioxide exhaust gas treatment system.

[0031] In practice, a sufficient amount of crude selenium dioxide is loaded into crucible 1, ensuring that several pieces of crude selenium dioxide are on the same horizontal plane within crucible 1. Then, the rightmost end of crucible 1 is moved to the leftmost end of heating device 2. Heating device 2 is activated, and crucible 1 is slid horizontally from left to right in the OX direction. The dripping device 3 is activated, and solvent is dripped into the area of ​​crucible 1 within heating device 2 to dissolve the crude selenium dioxide and obtain a solid-liquid mixture. As the temperature rises, the solid-liquid mixture in crucible 1 begins to evaporate and recrystallize. Finally, impurities with high solubility in the liquid phase gather at the leftmost end of the crystals in crucible 1, while impurities with low solubility in the liquid phase gather at the rightmost end of the crystals in crucible 1. After removing the impurities at both ends of the crystals, high-purity selenium dioxide is obtained.

[0032] The apparatus provided in this invention introduces a dissolution-crystallization system based on zone melting, constructing a purification environment of step zone dissolution. Utilizing the relative sliding of the crucible 1 and the heating device 2, and the synergistic effect of the dripping device 3, a continuous dynamic zone of dissolution-evaporation-recrystallization is formed in space. This not only significantly improves the crystallization efficiency and purification effect of a single operation, but also enhances the impurity segregation effect by controlling the movement of the dissolution front and the crystallization front. In particular, it achieves efficient separation of difficult-to-remove impurities such as tellurium with a partition coefficient close to 1, thereby breaking through the purity limit of traditional multiple crystallization. This provides a feasible technical path for preparing high-purity selenium dioxide of 7N and above. At the same time, the principle of this apparatus is universal and can be extended to the high purification process of other soluble compounds.

[0033] In some embodiments, such as Figure 1 As shown, the device also includes a sliding device 4; The sliding device 4 includes a first pulley 41 and a second pulley 42; In the first direction, the first pulley 41 and the second pulley 42 are respectively connected to both ends of the crucible 1, and the heating device 2 is located between the first pulley 41 and the second pulley 42; The crucible 1 moves along the first direction under the drive of the sliding device 4.

[0034] It should be noted that the sliding device 4 is a mechanical transmission mechanism that provides directional movement power for the crucible 1; The first pulley 41 and the second pulley 42 are the core guiding and transmission components in the sliding device 4. The first pulley 41 and the second pulley 42 can be connected to the motor by pulley blocks, belts or lead screws, etc., to automatically control the moving speed and position of the crucible 1. like Figure 1 As shown, the first pulley 41 is fixedly connected to the rightmost or leftmost end of the crucible 1 in the OX direction, and the second pulley 42 is arranged opposite to the first pulley 41 in the OX direction. like Figure 1 As shown, when the device includes a support platform 5, the first pulley 41 and the second pulley 42 both slide horizontally along the OX direction on the side of the support platform 5 facing the crucible 1.

[0035] In this embodiment of the invention, a sliding device 4 comprising a first pulley 41 and a second pulley 42 is provided and connected to both ends of the crucible 1, so that the heating device 2 is located between the two pulleys. This constructs a stable and controllable crucible 1 translation mechanism, ensuring that the crucible 1 can move smoothly, continuously and precisely along the first direction. This allows the dissolution, evaporation and recrystallization zones to move synchronously at a constant rate, effectively avoiding crystallization interface disorder and incomplete impurity segregation caused by movement fluctuations, and significantly improving the stability of the entire purification process.

[0036] In some embodiments, such as Figure 1 and Figure 2 As shown, the crucible 1 includes a pot body 11, a first external part 12, and a second external part 13; The pot body 11 is filled with the crude selenium dioxide product; the first external part 12 and the second external part 13 are respectively connected to the opposite ends of the pot body 11. The first pulley 41 is connected to the first external part 12, and the second pulley 42 is connected to the second external part 13; The crucible 1 slides along the first external portion 12 toward the second external portion 13.

[0037] It should be noted that, as Figure 2 and Figure 3 As shown, where, Figure 3 (a) is a front view of the pot body 11, (b) is a top view of the pot body 11, and (c) is a side view of the pot body 11. The two ends of the pot body 11 in the OX direction are semi-circular arcs, and the first external part 12 and the second external part 13 are fixedly connected to the semi-circular arc areas at both ends of the crucible 1, respectively. The first external part 12 is connected to the first pulley 41 in the central region of the OY direction; the second external part 13 is connected to the first pulley 41 in the central region of the OY direction. The pot body 11 has a dimension of 300mm-5000mm in the OX direction; the first external part 12 has a dimension in the OX direction that is one-tenth of the dimension of the pot body 11 in the OX direction; the second external part 13 may have the same dimension as the first external part 12 or may have a different dimension in the OX direction. The material of the first external part 12 can be quartz, stainless steel, copper, aluminum, etc.; the material of the second external part 13 can be the same as or different from that of the first external part 12.

[0038] In this embodiment of the invention, the crucible 1 is configured to include a pot body 11 and a first external part 12 and a second external part 13 connected to its opposite ends, and is directly connected to the first pulley 41 and the second pulley 42 of the sliding device 4. This achieves a stable and reliable physical coupling between the crucible 1 and the transmission mechanism, ensuring that the crucible 1 is subjected to uniform force and runs smoothly when sliding along the first direction. This effectively avoids shaking or jamming that may occur due to improper connection, ensures the uniformity and consistency of the dissolution and crystallization areas, and further enhances the separation and purification effect.

[0039] In some embodiments, such as Figure 1 and Figure 2 As shown, the heater 21 is wrapped around the outer wall of the crucible 1.

[0040] It should be noted that the enclosure of the crucible 1 by the heater 21 means that the shape of the heater 21 matches the shape of the crucible 1, and the heater 21 partially surrounds the crucible 1. The heater 21 is wrapped around the outer wall of the crucible 1, and the opening of the crucible 1 in the OY direction is not covered by the heater 21.

[0041] In this embodiment of the invention, the heater 21 is wrapped around the outer wall of the crucible 1, which helps to improve the heat utilization efficiency and response speed, enabling the heating device 2 to provide more precise and stable temperature control for the material in the pot 11, and achieve efficient regional dissolution and clear crystallization interface.

[0042] In some embodiments, such as Figure 1 and Figure 2 As shown, the heater 21 includes a plurality of heating zones 211 and at least one transition zone 212; The plurality of heating zones 211 and at least one transition zone 212 are arranged in the first direction.

[0043] It should be noted that the heating zone 211 is the section of the heater 21 that can actively heat and provide heat to the crucible 1. Its function is to locally heat the material so that it can be fully dissolved and / or maintain evaporation. The heater 21 corresponding to the heating zone 211 is equipped with a spiral electric heating wire inside, which is used to heat the crucible 1; The transition zone 212 is a section of the heater 21 that is not actively heated. Its function is to form a gradient region for natural cooling, providing the necessary thermal environment for the cooling of the solid-liquid mixture and the recrystallization of selenium dioxide. There is no heating component inside the heater 21 corresponding to the transition zone 212. In this embodiment of the invention, the non-heated transition zone 212 is set on the heater 21 to ensure that the solvent in the crucible 1 corresponding to the transition zone 212 is not evaporated by heating, thus avoiding the situation where purification cannot be achieved.

[0044] In some embodiments, such as Figure 1 and Figure 2 As shown, the heating device 2 includes a plurality of heaters 21, and the heating zone 211 and the transition zone 212 formed by the plurality of heaters 21 are alternately arranged in the first direction.

[0045] It should be noted that the heating device 2 may include 2, 4, 6, or other heaters 21; like Figure 1 As shown, preferably, the heating device 2 includes three heaters 21; the three heaters 21 are arranged sequentially along the OX direction; the three heaters 21 are turned on simultaneously, and the heating zones 211 on the three heaters 21 have the same heating temperature; like Figure 1 and Figure 4 As shown, where, Figure 4 (a) is a front view of heater 21, (b) is a top view of heater 21, and (c) is a side view of heater 21. The heater 21 has alternating heating zones 211 and transition zones 212, forming a U-shaped or semi-circular heater 21. The heating zones 211, transition zones 212, and heating zones 211, or transition zones 212, heating zones 211, and transition zones 212, are arranged sequentially along the OX direction. Preferably, the heating zones 211, transition zones 212, and heating zones 211 are arranged sequentially along the OX direction.

[0046] In this embodiment of the invention, by setting up multiple heaters 21, and alternating the heating zone 211 and transition zone 212 of the multiple heaters 21, the purification efficiency can be improved on the one hand, and on the other hand, by setting each heater 21 to heat on both sides in the OX direction and not heat in the middle, it is ensured that the solvent in the crucible 1 above the middle position is not evaporated by heating, and the purification can be carried out continuously.

[0047] In some embodiments, such as Figure 1 As shown, the heating device 2 includes a plurality of heaters 21; In the first direction, the distance between two adjacent heaters 21 is 10mm-300mm.

[0048] It should be noted that the multiple heaters 21 have the same dimensions in the OX direction and the same dimensions in the OY direction. That is, the multiple heaters 21 are located on the same horizontal plane in the OX direction on the side away from the support platform 5; in the OX direction, the distance between two adjacent heaters 21 is the same. For example, the distance between two adjacent heaters 21 is 10mm, 20mm, 30mm, 40mm, 50mm, 60mm, 70mm, 80mm, 90mm, 100mm, 150mm, 200mm, 250mm, or 300mm.

[0049] In this embodiment of the invention, the heating device 2 is configured as multiple independent heaters 21 and arranged at a specific interval of 10mm-300mm in the first direction, so that the crucible 1 periodically undergoes heating and cooling stages during the sliding process, thereby forming a series of narrow and steep temperature gradient regions inside the material, which greatly enhances the local partial condensation effect.

[0050] In some embodiments, such as Figure 1 As shown, the dripping device 3 includes at least one dripper 31; The heater 21 includes at least one heating zone 211 and a transition zone 212; The dripper 31 and the transition zone 212 are respectively arranged in a second direction perpendicular to the first direction; The temperature of the heating zone 211 is higher than the temperature of the transition zone 212.

[0051] It should be noted that the dripping device 31 can be a burette, a peristaltic pump, etc. like Figure 1 As shown, the distance between the outlet of the dripper 31 and the transition zone 212 on the OX plane is 5mm-50mm. The number of drippers 31 is the same as the number of transition zones 212 on heater 21; The second direction is Figure 1 The OY direction is shown; The temperature of heating zone 211 is 80℃-300℃; the temperature of transition zone 212 is 30℃-80℃.

[0052] In this embodiment of the invention, the dropper 31 in the dropper device 3 and the transition zone 212 in the heater 21 are correspondingly set in a second direction perpendicular to the first direction, and the temperature of the heating zone 211 is ensured to be higher than that of the transition zone 212. This allows the solvent to be accurately dropped onto the crucible 1 position corresponding to the relatively lower temperature transition zone 212, avoiding the instantaneous and violent evaporation of the solvent in the high-temperature heating zone 211 and the possible splashing or crystallization interface disturbance. On the other hand, the temperature field environment of the transition zone 212 is used to allow the solvent to stably and effectively wet and dissolve the crude selenium dioxide, forming a solid-liquid mixture with controllable concentration.

[0053] Secondly, such as Figure 5 As shown, this embodiment of the invention also provides a method for preparing high-purity selenium dioxide, the method being applicable to the aforementioned apparatus for preparing high-purity selenium dioxide; the method includes: Step S1: Fill the crude selenium dioxide into the crucible 1, turn on the heating device 2, and slide the crucible 1 along the first direction. The heating device 2 heats the crucible 1 to 80℃-300℃. Step S2: Start the dripping device 3 and add solvent dropwise to the crucible 1 area that slides into the heating device 2 to dissolve the crude selenium dioxide and obtain a solid-liquid mixture. Under the heat provided by the heating device 2, the solid-liquid mixture evaporates, causing the crude selenium dioxide to recrystallize and precipitate high-purity selenium dioxide crystals. The solvent is selected from water, ethanol, ammonia, and hydrochloric acid. The moving speed of the crucible 1 is 0.25 mm / min to 3 mm / min; The dripping rate of the dripping device 3 is 0.3 ml / min to 3.6 ml / min.

[0054] It should be noted that zone melting utilizes the slow passage of solid material through the molten zone, and through the segregation effect, impurities are redistributed between the solid and liquid phases. Unlike zone melting, step zone dissolution is the core process of this invention. Step zone dissolution forms a moving dissolution zone by locally adding solvent, accompanied by evaporation and recrystallization processes. It simulates the physical purification mechanism of zone melting but achieves purification based on the dissolution-crystallization mechanism. In this embodiment of the invention, the crude selenium dioxide is in powder form. Before loading it into the crucible 1, the crude selenium dioxide can be ground to about 200 mesh. The ground crude selenium dioxide is spread evenly in the crucible 1 so that the height of the crude selenium dioxide in different positions in the crucible 1 is consistent in the OY direction, so as to ensure that the amount of crude selenium dioxide in any position of the crucible is the same, so as to keep the dripping amount of the dripping device 3 constant. In this embodiment of the invention, after the solvent is dripped into the crude selenium dioxide, the solvent will penetrate to the bottom of the crude selenium dioxide powder, and the crude selenium dioxide in the dripping area of ​​the crucible 1 will dissolve rapidly to form a solid-liquid mixture. Heating device 2 heats crucible 1 to 80℃-300℃, meaning that heating zone 211 in heater 21 heats crucible 1, which has been slid to its position, to 80℃-300℃. For example, the crucible 1 is heated to 80℃, 90℃, 100℃, 150℃, 200℃, 250℃, and 300℃. Under the action of heating zone 211 in heater 21, the solvent in the solid-liquid mixture near the left side of heater 214 evaporates, causing selenium dioxide to recrystallize and precipitate. Among them, impurities such as tellurium oxide, antimony oxide, and mercury oxide, which have low solubility in the liquid phase, are enriched in the crystal, while sodium ions, potassium ions, and other impurities with high solubility in the liquid phase are enriched in the liquid phase. For example, the dripping rate of the dripping device 3 is 0.3 ml / min, 0.5 ml / min, 1 ml / min, 1.5 ml / min, 2 ml / min, 2.5 ml / min, 3 ml / min, and 3.6 ml / min. In this embodiment of the invention, the amount of liquid dripped needs to be strictly controlled according to the dissolution rate and evaporation rate of the substance. If the amount of liquid dripped is too large, the water in the crucible 1 above the heating zone 211 on both sides of the heater 21 will not be able to evaporate, and the liquid will permeate towards both ends of the heater 21, or even further away.

[0055] It should also be noted that the solubility ratio of impurities in the solid phase to the liquid phase is defined as the equilibrium partition coefficient k0. The equilibrium partition coefficient k0 is a key factor determining the dissolution and purification effect in the stepping zone. k0=C s / C l ; C s C represents the solubility of impurities in the selenium dioxide solid phase. lLet k be the solubility of the impurity in the selenium dioxide solution; the impurity migrates as crucible 1 moves, and impurities with k0>1 eventually accumulate at the head of crucible 1 (i.e., Figure 1 The rightmost end in the OX direction), impurities with k0 < 1 are ultimately enriched at the tail end of crucible 1 (i.e., Figure 1 (the leftmost end in the OX direction); the greater the absolute difference between k0 and 1, the easier it is to separate impurities. For impurities with a K value close to 1 during zone melting, the preparation method provided in this embodiment of the invention has a better purification effect.

[0056] In some embodiments, the preparation method further includes: The crude selenium dioxide product is recycled 2-10 times for recrystallization; Specifically, the moving speed of the crucible 1 during odd-numbered recrystallization processes is greater than the moving speed of the crucible 1 during even-numbered recrystallization processes; and the dripping speed of the dripping device 3 during odd-numbered recrystallization processes is greater than the dripping speed of the dripping device 3 during even-numbered recrystallization processes.

[0057] It should be noted that during the odd-numbered recrystallization processes, the moving speed of crucible 1 is 1 mm / min-2 mm / min, and the dropping speed of the dropping device 3 is 1.5 ml / min-2.5 ml / min; for example, the moving speed of crucible 1 is 1 mm / min, 1.2 mm / min, 1.5 mm / min, 1.7 mm / min, 1.8 mm / min, and 2 mm / min, and the dropping speed of the dropping device 3 is 1.5 ml / min, 1.7 ml / min, 1.9 ml / min, 2.0 ml / min, 2.2 ml / min, 2.3 ml / min, and 2.5 ml / min. During even-numbered recrystallization processes, the moving speed of crucible 1 is 0.3 mm / min-0.8 mm / min, and the dropping speed of the dropping device 3 is 0.4 ml / min-0.8 ml / min; for example, the moving speed of crucible 1 is 0.3 mm / min, 0.4 mm / min, 0.5 mm / min, 0.6 mm / min, 0.7 mm / min, and 0.8 mm / min, and the dropping speed of the dropping device 3 is 0.4 ml / min, 0.5 ml / min, 0.6 ml / min, 0.7 ml / min, and 0.8 ml / min. In this embodiment of the invention, it was found that excessively high dripping speeds can lead to insufficient time for solvent to evaporate, resulting in excessive accumulation and hindering evaporation and crystallization. Conversely, excessively high sliding speeds can result in insufficient heating time for the liquid in crucible 1, preventing sufficient evaporation and also affecting crystallization. Therefore, this embodiment further specifies that the dripping speed in odd-numbered cycles is 1.5 ml / min-2.5 ml / min, and the sliding speed is 1 mm / min-2 mm / min, ensuring adequate overall wetting. While in even-numbered recrystallization cycles, although the combination of a dripping speed of 0.4 ml / min-0.8 ml / min and a sliding speed of 0.3 mm / min-0.8 mm / min results in excessive solvent evaporation, potentially causing the liquid to dry out after one heating cycle and leading to selenium dioxide caking, the combination of the dripping and sliding speeds in odd-numbered cycles overcomes this problem and prevents over-wetting, thus avoiding interference with crystallization.

[0058] To enable those skilled in the art to better understand this application, the following embodiments will be used to provide a detailed description of the apparatus and method for preparing high-purity selenium dioxide provided in this application.

[0059] Example 1 refer to Figure 1 The apparatus shown for preparing high-purity selenium dioxide includes the following steps: (1) Put 800g of selenium dioxide powder with a purity of 4N and a particle size of about 200 mesh (i.e. crude selenium dioxide) into crucible 1, spread its surface flat, and try to ensure that the height is consistent in the OY direction. (2) At the beginning, the rightmost end of the crucible 1 is located at the leftmost end of the heater 21. First, turn on the heater 21 and set the temperature of the heating zone 211 of the heater 21 to 250°C. After the heater 21 reaches the set value, turn on the dropper 31 and set the drop rate to 0.6 ml / min. Drop pure water into the selenium dioxide powder. Part of the selenium dioxide dissolves to form a solid-liquid mixture. At the same time, turn on the sliding device 4 and set the moving speed of the crucible 1 to 0.5 mm / min. The crucible 11 moves from left to right. (3) Under the action of the heating zone 211 on the left side of the heater 21, during the dissolution process in the stepping area, the water in the solution near the left side of the heater 21 evaporates, causing selenium dioxide to recrystallize and precipitate; impurities such as tellurium oxide, antimony oxide and mercury oxide, which have low solubility in the liquid phase, are enriched in the crystal; sodium ions, potassium ions, etc., which have high solubility in the liquid phase, are enriched in the liquid phase. (4) When the left end of crucible 1 moves to the rightmost side of heater 21, one cycle is completed; since there is a combination of heater 21 and dripping device 3, each cycle can complete three steps of dissolution and purification in the stepping area; (5) Repeat the previous operation to complete 9 cycles, that is, 27 zone meltings. Then remove the selenium dioxide from both ends of the crucible 11 and obtain high-purity selenium dioxide with a purity of 5N in the middle section.

[0060] Example 2 refer to Figure 1 The apparatus shown for preparing high-purity selenium dioxide includes the following steps: (1) Put 800g of selenium dioxide powder (crude selenium dioxide) with a purity of 4N and a particle size of about 200 mesh into crucible 1, spread its surface flat, and try to ensure that the height is consistent in the OY direction. (2) At the beginning, the rightmost end of the crucible 1 is located at the leftmost end of the heater 21. First, turn on the heater 21 and set the temperature of the heating zone 211 of the heater 21 to 250°C. After the heater 21 reaches the set value, turn on the dropper 31 and set the drop rate to 1.8 ml / min. Drop pure water into the selenium dioxide powder. Part of the selenium dioxide dissolves to form a solid-liquid mixture. At the same time, turn on the sliding device 4 and set the moving speed of the crucible 1 to 1.5 mm / min. The crucible 11 moves from left to right. (3) Under the action of the heating zone 211 on the left side of the heater 21, during the dissolution process in the stepping area, the water in the solution near the left side of the heater 21 evaporates, causing selenium dioxide to recrystallize and precipitate; impurities such as tellurium oxide, antimony oxide and mercury oxide, which have low solubility in the liquid phase, are enriched in the crystal; sodium ions, potassium ions, etc., which have high solubility in the liquid phase, are enriched in the liquid phase. (4) When the left end of crucible 1 moves to the rightmost side of heater 21, one cycle is completed; since there is a combination of heater 21 and dripping device 3, each cycle can complete three steps of dissolution and purification in the stepping area; (5) In the second cycle (i.e., the even-numbered recrystallization process), the dropping speed of the dropping device 3 is changed to 0.6 ml / min, and the moving speed of the crucible 11 is changed to 0.5 mm / min; (6) In the subsequent third cycle (i.e., the odd-numbered recrystallization process), the dripping speed of the dripping device 3 and the moving speed of the crucible 1 are set to be consistent with those of the first cycle to avoid water accumulation; (7) In subsequent cycles, the two settings are alternated. The settings for odd-numbered recrystallization processes are the same as those for the first cycle, and the settings for even-numbered recrystallization processes are the same as those for the second cycle. After completing 9 cycles, i.e. 27 zone meltings, the selenium dioxide at both ends of the crucible 11 is removed, and high-purity selenium dioxide with a purity of 7N is obtained in the middle section.

[0061] In summary, the apparatus and method for preparing high-purity selenium dioxide provided in this invention can effectively remove impurities with significantly different saturated solubility in liquid phases such as water and ethanol compared to the solid phase of selenium dioxide, thus achieving the preparation of high-purity selenium dioxide. This invention unifies the dissolution crystallization method and the melt crystallization method using a mechanism similar to zone melting, extending it to most soluble compounds. The apparatus and method provided in this invention have advantages such as high purity upper limit, low energy consumption, and strong applicability.

[0062] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0063] Although preferred embodiments of the present application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present application.

[0064] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0065] The above provides a detailed description of the apparatus and method for preparing high-purity selenium dioxide provided in this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. An apparatus for preparing high-purity selenium dioxide, characterized in that, include: Crucible (1), heating device (2) and dripping device (3); The crucible (1) is capable of sliding relative to the heating device (2) in a first direction; The heating device (2) includes at least one heater (21); The dripping device (3) is located on the side of the crucible (1) away from the heating device (2); The crucible (1) is filled with crude selenium dioxide. During the process of the crucible (1) sliding along the first direction, the dripping device (3) is configured to drip solvent onto the crucible (1) to dissolve the crude selenium dioxide and obtain a solid-liquid mixture. The heating device (2) is configured to heat the solid-liquid mixture in the crucible (1) to evaporate and recrystallize it to obtain high-purity selenium dioxide.

2. The apparatus for preparing high-purity selenium dioxide according to claim 1, characterized in that, The device also includes a sliding device (4); The sliding device (4) includes a first pulley (41) and a second pulley (42); In the first direction, the first pulley (41) and the second pulley (42) are respectively connected to both ends of the crucible (1), and the heating device (2) is located between the first pulley (41) and the second pulley (42); The crucible (1) moves along the first direction under the drive of the sliding device (4).

3. The apparatus for preparing high-purity selenium dioxide according to claim 2, characterized in that, The crucible (1) includes a pot body (11), a first external part (12), and a second external part (13). The pot body (11) is filled with the crude selenium dioxide product; the first external part (12) and the second external part (13) are respectively connected to the opposite ends of the pot body (11); The first pulley (41) is connected to the first external part (12), and the second pulley (42) is connected to the second external part (13); The crucible (1) slides along the first external part (12) toward the second external part (13).

4. The apparatus for preparing high-purity selenium dioxide according to claim 1, characterized in that, The heater (21) is wrapped around the outer wall of the crucible (1).

5. The apparatus for preparing high-purity selenium dioxide according to claim 1, characterized in that, The dripping device (3) includes at least one dripper (31); The heater (21) includes at least one heating zone (211) and a transition zone (212); The dropper (31) and the transition zone (212) are respectively arranged in a second direction perpendicular to the first direction; The temperature of the heating zone is higher than the temperature of the transition zone.

6. The apparatus for preparing high-purity selenium dioxide according to claim 5, characterized in that, The heater (21) includes a plurality of heating zones (211) and at least one transition zone (212). The plurality of heating zones (211) and at least one transition zone (212) are arranged in the first direction.

7. The apparatus for preparing high-purity selenium dioxide according to claim 6, characterized in that, The heating device (2) includes a plurality of heaters, and the heating zone (211) and the transition zone (212) formed by the plurality of heaters are alternately arranged in the first direction.

8. The apparatus for preparing high-purity selenium dioxide according to claim 1 or 7, characterized in that, The heating device (2) includes a plurality of the heaters (21); In the first direction, the distance between two adjacent heaters (21) is 10mm-300mm.

9. A method for preparing high-purity selenium dioxide, characterized in that, The preparation method is applicable to the apparatus for preparing high-purity selenium dioxide according to any one of claims 1-8; the preparation method includes: The crude selenium dioxide product is loaded into the crucible, the heating device is turned on, and the crucible is slid along the first direction. The heating device heats the crucible to 80℃-300℃. The dripping device is activated, and solvent is added dropwise to the crucible area that slides into the heating device to dissolve the crude selenium dioxide and obtain a solid-liquid mixture. Under the heat provided by the heating device, the solid-liquid mixture evaporates, causing the crude selenium dioxide to recrystallize and precipitate high-purity selenium dioxide crystals. The solvent is selected from water, ethanol, ammonia, and hydrochloric acid. The crucible moves at a speed of 0.25 mm / min to 3 mm / min. The dripping rate of the dripping device is 0.3 ml / min to 3.6 ml / min.

10. The method for preparing high-purity selenium dioxide according to claim 9, characterized in that, The preparation method further includes: The crude selenium dioxide product is recycled 2-10 times for recrystallization; Specifically, the crucible's moving speed is greater during odd-numbered recrystallization processes than during even-numbered recrystallization processes; and the dropping speed of the dropping device is greater during odd-numbered recrystallization processes than during even-numbered recrystallization processes.

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