A device and a processing technology for producing low-temperature sodium precipitation of lithium hydroxide

Abstract

The application relates to the technical field of crystallization separation, and discloses a lithium hydroxide production low-temperature sodium precipitation equipment and processing technology, which comprises a cooling water pre-cooler, a first-stage refrigeration heat exchanger, a first-stage refrigeration crystallizer, a first-stage thickener and a first-stage centrifuge. The cooling water pre-cooler is connected with the first-stage refrigeration heat exchanger. The first-stage refrigeration crystallizer is provided with a first liquid inlet at the top and a first liquid outlet at the bottom. The first-stage refrigeration heat exchanger is connected with the first liquid inlet. The first liquid outlet is connected with the first-stage thickener. The first-stage thickener is connected with the first-stage centrifuge. The first-stage centrifuge is connected with a first-stage mother liquor tank. Through the technical scheme, the problem of low heat exchange efficiency and long crystallization time in the lithium hydroxide production sodium precipitation process in the prior art is solved.

Description

Technical Field

[0001] This invention relates to the field of crystallization separation technology, specifically to an apparatus and processing technology for producing sodium from lithium hydroxide at low temperatures. Background Technology

[0002] Lithium and its compounds are new materials needed for the development of modern science and technology and will become one of the main energy sources for mankind in the future. In recent years, with the rapid development and popularization of the automobile industry and the development of the metallurgical machinery industry, the demand for lithium hydroxide has increased significantly. At present, the sulfuric acid roasting-freezing method is the main method for producing lithium hydroxide in China. In this method, the denitrification process of cooling crystallization of sodium sulfate (also known as sodium sulfate decahydrate) is a key step. The quality of sodium sulfate separated in the denitrification process directly affects the quality and yield of lithium.

[0003] Traditional methods for crystallizing Glauber's salt typically use a jacketed or coiled stirred tank as the crystallizer. The raw material is added to the tank all at once, and then chilled brine is circulated through the jacket or coil to exchange heat with the solution inside. Once the material temperature drops to the target temperature, the discharge valve is opened to release the material into an intermittent centrifuge for solid-liquid separation. This intermittent cooling crystallization process for Glauber's salt has low heat exchange efficiency, long crystallization time, requires frequent operator intervention, is labor-intensive, has high operating costs, and cannot ensure continuous and normal production. Summary of the Invention

[0004] This invention proposes an equipment and processing technology for producing sodium from lithium hydroxide at low temperature, which solves the problems of low heat exchange efficiency and long crystallization time in the process of producing sodium from lithium hydroxide in related technologies.

[0005] The technical solution of the present invention is as follows: An apparatus for producing sodium from lithium hydroxide at low temperature includes: Cooling water precooler A primary refrigeration heat exchanger, wherein the cooling water precooler is connected to the primary refrigeration heat exchanger. A primary cryogenic crystallizer, having a first liquid inlet at the top and a first liquid outlet at the bottom, wherein a primary cryogenic heat exchanger is connected to the first liquid inlet. A primary thickener, with the first liquid outlet leading to the primary thickener. A primary centrifuge, with the primary thickener connected to the primary centrifuge. A primary mother liquor tank, to which the primary centrifuge is connected.

[0006] As a further technical solution, it also includes: A secondary refrigeration heat exchanger is connected to the primary mother liquor tank. A secondary cryogenic crystallizer, having a second liquid inlet at the top and a second liquid outlet at the bottom, wherein a secondary cryogenic heat exchanger is connected to the second liquid inlet. The second outlet leads to the secondary thickener. A secondary centrifuge, wherein the secondary thickener leads to the secondary centrifuge. A secondary mother liquor tank, to which the secondary centrifuge is connected.

[0007] As a further technical solution, it also includes: The mother liquor precooler is connected to the secondary mother liquor tank, and the mother liquor precooler is heat-exchange connected to the cooling water precooler. Both the primary thickener and the secondary thickener have overflow ports.

[0008] As a further technical solution, both the primary freeze crystallizer and the secondary freeze crystallizer include: An internal flow tube having an internal flow cavity for upward flow of solution. An external flow tube is provided, and an external flow cavity is formed between the external flow tube and the internal flow tube. The upper end of the internal flow cavity is connected to the upper end of the external flow cavity, and the lower end of the internal flow cavity is connected to the lower end of the external flow cavity. The external flow tube has a liquid inlet at the top and a liquid outlet at the bottom. The first wall scraping assembly is slidably and vertically disposed on the inner wall of the inner flow pipe. The second wall scraping assembly is slidably mounted on the outer wall of the inner flow tube and located inside the outer flow cavity.

[0009] As a further technical solution, the first wall scraping assembly includes: A first magnetic element, which is slidably mounted on the inner wall of the inner flow tube, and is annular in shape. A first scraper is rotatably mounted on the first magnetic component. The rotation axis of the first scraper is the same as the axis of the inner flow pipe. The first scraper has a first scraping part that abuts against the inner wall of the inner flow pipe.

[0010] As a further technical solution, the second wall scraping assembly includes: A second magnetic component, which is slidably mounted on the outer wall of the inner flow tube, is annular. The first and second magnetic components are magnetically attracted to each other, and slide synchronously after either the first or second magnetic component slides. The second scraper is rotatably mounted on the second magnetic component. The rotation axis of the first scraper is the same as that of the second scraper. The second scraper has a second scraping part that abuts against the outer wall of the inner flow tube. Both the first scraping part and the second scraping part have notches.

[0011] As a further technical solution, the first wall scraping assembly also includes: A first guide member is slidably mounted on the first scraper. The first guide member is annular and has a first spiral guide groove on its outer wall. A first flow channel is formed between the outer wall of the first guide member and the inner wall of the first scraper. The first guide vane has one end rotatably disposed on the inner wall of the first scraper, and the other end has a first sliding part. The first sliding part and the rotation axis of the first guide vane are offset in the length direction of the first guide vane. The first sliding part rotates and slides in the first spiral guide groove. After the first guide member is raised and lowered and slids, the groove wall of the first spiral guide groove pushes the first guide vane to swing.

[0012] As a further technical solution, the inner wall of the first scraper has a vertical second guide groove, the first guide has a second sliding part, the second sliding part is slidably disposed in the second guide groove, and further includes: The first elastic element has one end acting on the inner wall of the second guide groove and the other end acting on the second sliding part, providing a downward force to the second sliding part.

[0013] As a further technical solution, the second wall scraping assembly also includes: The second guide vane is oscillatingly disposed on the outer wall of the second scraper. Both the first and second guide vanes have arc-shaped beveled edges. The second guide member is slidably mounted on the outer wall of the second scraper. The second guide member is annular and has a stop. The second guide blade has an arc-shaped guide surface. The stop and the arc-shaped guide surface abut against each other. After the second guide member slides downwards on the second scraper, the stop pushes the second guide blade to swing. A guide wheel is rotatably mounted on the second guide member and abuts against the outer wall of the inner flow pipe. A power-storing coil spring, one end of which is mounted on the guide wheel and the other end of which is mounted on the shaft of the guide wheel, provides the force for the rotation of the guide wheel.

[0014] A process for producing sodium from lithium hydroxide at low temperature involves using the equipment described above to perform sodium precipitation at low temperature during the lithium hydroxide production process.

[0015] The working principle and beneficial effects of this invention are as follows: In this invention, the system first pre-cools the raw material liquid using a cooling water precooler, employing low-temperature circulating water as the cooling medium to effectively reduce energy consumption in the subsequent freezing process. Simultaneously, it provides a pre-treated low-temperature solution for the first-stage refrigeration heat exchanger. The pre-cooled solution is introduced into the first-stage refrigeration heat exchanger, which features a high-efficiency heat exchange tube design. Low-temperature refrigerants such as ammonia or Freon circulate internally, facilitating efficient heat exchange with the solution and further reducing the solution temperature to near the crystallization temperature, creating favorable conditions for the crystallization process. The pre-cooled and first-stage refrigeration-treated solution enters the first-stage refrigeration crystallizer through the first inlet. The crystallizer has an optimized internal structure design to ensure a uniform supersaturated state during flow, promoting the formation and growth of sodium sulfate crystals. Temperature and pressure control devices are designed at the top and bottom of the crystallizer to precisely control the crystallization process, ensuring uniform crystal size and high purity.

[0016] The suspension containing a large number of sodium sulfate crystals at the bottom of the primary cryogenic crystallizer flows into the primary thickener through the first outlet. The thickener further aggregates the crystals through slow stirring or gravity settling, increasing the concentration before solid-liquid separation and reducing the burden on subsequent centrifugal separation. The thickened suspension is then sent to the primary centrifuge for high-speed centrifugal separation. Under centrifugal force, the solid sodium sulfate crystals rapidly separate from the mother liquor, achieving efficient solid-liquid separation. The centrifuge is designed with automatic discharge and level control functions to ensure continuous and stable operation. The mother liquor after centrifugation is collected in the primary mother liquor tank. This mother liquor contains incompletely crystallized lithium salts and other components, which can be further recycled or recycled back to the front end of the system for reprocessing to improve resource utilization. In summary, this low-temperature sodium precipitation equipment, through a continuous process of precooling, freezing, crystallization, thickening, centrifugation, and recovery, achieves a highly efficient and energy-saving lithium hydroxide production process, improving product quality and production efficiency while reducing energy consumption and operating costs, meeting the environmental protection and sustainability requirements of modern chemical production. Attached Figure Description

[0017] The preferred embodiments will now be described in a clear and easy-to-understand manner, in conjunction with the accompanying drawings, to further explain the above-mentioned characteristics, technical features, advantages, and implementation methods of the present invention.

[0018] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 for Figure 1 A partial structural diagram of section A; Figure 3 This is a schematic diagram of the structure of the cryo-crystallizer in this invention; Figure 4 For this Figure 3 Internal structure diagram; Figure 5 This is a schematic diagram of the structure of the first wall scraping component in this invention; Figure 6 This is a schematic diagram of the structure of the first guide member in this invention; Figure 7 This is a schematic diagram of the structure of the second wall scraping component in this invention; Figure 8 This is a schematic diagram of the baffle structure in the present invention.

[0019] In the diagram: Cooling water precooler-1, primary refrigeration heat exchanger-2, primary refrigeration crystallizer-3, first inlet-301, first outlet-302, primary thickener-4, overflow outlet-401, primary centrifuge-5, primary mother liquor tank-6, secondary refrigeration heat exchanger-7, secondary refrigeration crystallizer-8, second inlet-801, second outlet-802, secondary thickener-9, secondary centrifuge-10, secondary mother liquor tank-11, mother liquor precooler-12, internal flow pipe-1100, internal flow cavity-1101, external flow cylinder-1200, external flow cavity-1201, first wall scraping assembly-1300, second wall scraping assembly-1400, first magnetic component-13 10, First scraper - 1320, First scraper section - 1321, Second guide groove - 1322, First guide member - 1330, First spiral guide groove - 1331, First guide channel - 1332, Second sliding section - 1333, First guide blade - 1340, First sliding section - 1341, First elastic member - 1350, Second magnetic member - 1410, Second scraper - 1420, Second scraper section - 1421, Notch section - 1422, Second guide blade - 1430, Arc-shaped bevel - 1431, Arc-shaped guide surface - 1432, Second guide member - 1440, Stop section - 1441, Guide wheel - 1450, Energy-storing coil spring - 1460. Detailed Implementation

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without any creative effort.

[0021] To keep the drawings concise, each drawing only schematically shows the parts relevant to the invention; these do not represent the actual structure of the product. Furthermore, for ease of understanding, in some drawings, only one of components with the same structure or function is schematically shown, or only one is labeled. In this document, "one" not only means "only one," but can also mean "more than one," and "several" includes "two" and "more than two."

[0022] In this document, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0023] Furthermore, in the description of this application, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0024] Reference Figures 1-8 An embodiment of the present invention provides an apparatus for producing sodium from lithium hydroxide at low temperature, comprising a cooling water precooler 1, a primary refrigeration heat exchanger 2, the cooling water precooler 1 leading to the primary refrigeration heat exchanger 2, a primary refrigeration crystallizer 3, the primary refrigeration crystallizer 3 having a first liquid inlet 301 at the top and a first liquid outlet 302 at the bottom, the primary refrigeration heat exchanger 2 leading to the first liquid inlet 301, a primary thickener 4, the first liquid outlet 302 leading to the primary thickener 4, a primary centrifuge 5, the primary thickener 4 leading to the primary centrifuge 5, and a primary mother liquor tank 6, the primary centrifuge 5 leading to the primary mother liquor tank 6.

[0025] In this embodiment, the system first pre-cools the raw material liquid using a cooling water precooler 1, employing low-temperature circulating water as the cooling medium to effectively reduce energy consumption in the subsequent freezing process. Simultaneously, it provides a pre-treated low-temperature solution for the first-stage refrigeration heat exchanger 2. The pre-cooled solution is introduced into the first-stage refrigeration heat exchanger 2, which features a high-efficiency heat exchange tube design. Low-temperature refrigerants such as ammonia or Freon circulate internally, facilitating efficient heat exchange with the solution and further reducing the solution temperature to near the crystallization temperature, creating favorable conditions for the crystallization process. The pre-cooled and first-stage refrigeration-treated solution enters the first-stage refrigeration crystallizer 3 through the first inlet 301. The crystallizer has an optimized internal structure design to ensure a uniform supersaturated state during the flow process, promoting the formation and growth of Glauber's salt crystals. Temperature and pressure control devices are designed at the top and bottom of the crystallizer to precisely control the crystallization process, ensuring uniform crystal size and high purity.

[0026] The suspension containing a large number of sodium sulfate crystals at the bottom of the primary cryogenic crystallizer 3 flows into the primary thickener 4 through the first outlet 302. The thickener further aggregates the crystals through slow stirring or gravity settling, increasing the concentration before solid-liquid separation and reducing the burden on subsequent centrifugal separation. The thickened suspension is then sent to the primary centrifuge 5 for high-speed centrifugal separation. Under centrifugal force, the solid sodium sulfate crystals rapidly separate from the mother liquor, achieving efficient solid-liquid separation. The centrifuge is designed with automatic discharge and level control functions to ensure continuous and stable operation. The mother liquor after centrifugal separation is collected in the primary mother liquor tank 6. This mother liquor contains incompletely crystallized lithium salts and other components, which can be further recycled or recycled back to the front end of the system for reprocessing to improve resource utilization. In summary, this low-temperature sodium precipitation equipment, through a continuous process of pre-cooling, freezing, crystallization, thickening, centrifugation, and recovery, achieves a highly efficient and energy-saving lithium hydroxide production process, improving product quality and production efficiency while reducing energy consumption and operating costs, meeting the environmental protection and sustainability requirements of modern chemical production.

[0027] Furthermore, it also includes a secondary refrigeration heat exchanger 7, a primary mother liquor tank 6 leading to the secondary refrigeration heat exchanger 7, a secondary refrigeration crystallizer 8, the secondary refrigeration crystallizer 8 having a second liquid inlet 801 at the top and a second liquid outlet 802 at the bottom, the secondary refrigeration heat exchanger 7 leading to the second liquid inlet 801, a secondary thickener 9, the second liquid outlet 802 leading to the secondary thickener 9, a secondary centrifuge 10, the secondary thickener 9 leading to the secondary centrifuge 10, and a secondary mother liquor tank 11, the secondary centrifuge 10 leading to the secondary mother liquor tank 11.

[0028] In this embodiment, the mother liquor in the primary mother liquor tank 6, after initial treatment but still containing a certain amount of lithium salt, is transported to the secondary refrigeration heat exchanger 7. This heat exchanger also employs a highly efficient heat exchange design, utilizing a low-temperature refrigerant to further reduce the temperature of the mother liquor, creating deeper supersaturation conditions to continue precipitating residual sodium sulfate crystals and ensuring further purification of the lithium salt. The mother liquor treated by the secondary refrigeration heat exchanger 7 enters the secondary refrigeration crystallizer 8 through the second inlet 801. This crystallizer design optimizes the crystallization environment, allowing finer crystals to precipitate while avoiding excessive growth of large crystal particles, ensuring the continuity and efficiency of the crystallization process. The suspension containing newly formed crystals at the bottom of the secondary refrigeration crystallizer 8 flows into the secondary thickener 9 through the second outlet 802. This step further concentrates the crystals by slowing the flow rate or utilizing the principle of gravity sedimentation, preparing for centrifugal separation. The thickened suspension is then introduced into the secondary centrifuge 10 for fine separation. This centrifuge is equipped with a finer filter or a higher rotation speed to capture smaller crystals while recovering more pure mother liquor. The mother liquor separated by the secondary centrifuge 10 is collected in the secondary mother liquor tank 11. This portion of the mother liquor may contain a small amount of incompletely crystallized lithium salts, which can be recycled as needed or subjected to final treatment and disposal, ensuring maximum resource utilization and environmental friendliness.

[0029] Furthermore, it also includes a mother liquor precooler 12, a secondary mother liquor tank 11 connected to the mother liquor precooler 12, and the mother liquor precooler 12 is heat exchanged with the cooling water precooler 1. Both the primary thickener 4 and the secondary thickener 9 have overflow ports 401.

[0030] In this embodiment, to further improve energy efficiency and optimize the entire production process, the mother liquor output from the secondary mother liquor tank 11 enters the mother liquor precooler 12 before being returned to the initial treatment stage. This precooler is connected to the cooling water precooler 1 via a heat exchange system to achieve effective heat transfer. Through this process, the temperature of the mother liquor is moderately reduced before entering the next cycle, which not only helps maintain the overall low-temperature environment of the system and reduce energy consumption, but also improves the efficiency of subsequent processing steps. Especially when undergoing deep cooling again via a refrigeration heat exchanger, precooling can significantly reduce the required refrigeration energy. For the primary thickener 4 and the secondary thickener 9, this embodiment specifically designs an overflow port 401. This design aims to automatically adjust the liquid level in the thickener to ensure that only a suspension of appropriate concentration enters the subsequent centrifugal separation step. When the liquid in the thickener reaches a predetermined height, the excess portion is discharged through the overflow port 401, returned to the previous process for reprocessing, or directly entered into the waste liquid treatment system. This self-regulating mechanism is crucial for maintaining stable operation in continuous production processes. It avoids clogging problems caused by excessively thick materials or materials containing too many solid particles, while ensuring the stability of product quality.

[0031] Furthermore, both the primary cryogenic crystallizer 3 and the secondary cryogenic crystallizer 8 include an inner flow pipe 1100, which has an inner flow cavity 1101 for upward flow of solution. An outer flow cylinder 1200 forms an outer flow cavity 1201 between the outer flow cylinder 1200 and the inner flow pipe 1100. The upper end of the inner flow cavity 1101 is connected to the upper end of the outer flow cavity 1201, and the lower end of the inner flow cavity 1101 is connected to the lower end of the outer flow cavity 1201. The outer flow cylinder 1200 has an inlet at the top and an outlet at the bottom. A first wall scraping assembly 1300 is slidably mounted on the inner wall of the inner flow pipe 1100. A second wall scraping assembly 1400 is slidably mounted on the outer wall of the inner flow pipe 1100 and located inside the outer flow cavity 1201.

[0032] In this embodiment, refer to Figures 3-8 The inner flow tube 1100 forms a closed inner flow cavity 1101, which is designed as a smooth cylindrical structure to facilitate stable fluidization of the solution during its ascent, promoting uniform crystal growth. The upper end of the inner flow tube 1100 is connected to the outer flow cavity 1201 via a transition section, and the lower end is similarly connected to the lower end of the outer flow cavity 1201, ensuring smooth solution circulation. The outer flow cylinder 1200 is arranged around the inner flow tube 1100, with the gap between them forming the outer flow cavity 1201. The outer flow cylinder 1200 has an inlet at the top for introducing saturated or supersaturated solutions for cooling, and an outlet at the bottom to discharge the solution via a pump or gravity. After heat exchange and cooling, the solution flows back into the device. The outer flow cavity 1201 is designed to maintain a low temperature through a temperature control unit, promoting the solution to reach crystallization conditions during circulation.

[0033] Considering that the inner wall of crystallizers in existing technologies is prone to scale and crystal deposits, which can easily lead to reduced product quality and even affect the safety of the equipment, this solution includes a first scraping assembly 1300 and a second scraping assembly 1400. These two assemblies slide on the inner and outer walls of the inner flow pipe 1100, respectively, scraping and cleaning the two inner wall locations where crystals are most likely to accumulate. The two scraping assemblies effectively remove attached crystals or scale, keeping the inner and outer walls of the inner flow pipe 1100 clean. This ensures the continuity and efficiency of the crystallization process while maintaining the long-term stable operation of the equipment.

[0034] Furthermore, the first wall scraping assembly 1300 includes a first magnetic element 1310, which is slidably disposed on the inner wall of the inner flow pipe 1100 and is annular. It also includes a first scraper 1320, which is rotatably disposed on the first magnetic element 1310. The rotation axis of the first scraper 1320 is the same as the axis of the inner flow pipe 1100. The first scraper 1320 has a first scraping portion 1321, which abuts against the inner wall of the inner flow pipe 1100.

[0035] In this embodiment, a high-strength annular first magnetic component 1310 is employed, which enables stable and reliable lifting and sliding. The annular design of the magnetic component ensures full contact with the inner wall, improving the stability and flexibility of the entire scraping system. The first scraper 1320 is designed as a rotatable structure and is directly mounted on the first magnetic component 1310. Through a set rotation drive system, the scraper can rotate smoothly along the same path as the inner flow pipe 1100. This design not only covers a larger area of ​​the inner wall but also effectively avoids jamming of the scraper through rotational motion, reducing wear on the inner wall. The first scraper 1321 is designed as a soft and wear-resistant material, such as polyurethane, Teflon-coated steel, or flexible stainless steel, ensuring that it can effectively scrape away crystals and scale when in contact with the inner wall of the inner flow pipe 1100 without damaging the inner wall. The shape of the scraper is carefully designed according to the contour of the inner wall of the inner flow pipe 1100 to ensure optimal contact and cleaning effect.

[0036] Furthermore, the second wall scraping assembly 1400 includes a second magnetic element 1410, which is slidably mounted on the outer wall of the inner flow pipe 1100. The second magnetic element 1410 is annular. The first magnetic element 1310 and the second magnetic element 1410 are magnetically attracted to each other. The first magnetic element 1310 or the second magnetic element 1410 slides synchronously after sliding. The second scraper 1420 is rotatably mounted on the second magnetic element 1410. The rotation axis of the first scraper 1320 is the same as the rotation axis of the second scraper 1420. The second scraper 1420 has a second scraping portion 1421, which abuts against the outer wall of the inner flow pipe 1100. Both the first scraping portion 1321 and the second scraping portion 1421 have a notch portion 1422.

[0037] In this embodiment, the second magnetic component 1410 is designed as a ring, fitting snugly against the outer wall of the inner flow pipe 1100. It is made of high-performance magnetic material, ensuring a strong magnetic attraction with the first magnetic component 1310 inside the inner flow pipe 1100. This eliminates the need for direct physical connection, enabling synchronous lifting and sliding of the inner and outer magnetic components. This design reduces the complexity of mechanical connections and improves the system's sealing and reliability. The first magnetic component 1310 and the second magnetic component 1410 are attracted by magnetic force; when one slides, the other slides synchronously, ensuring a high degree of synchronization between the first scraper component 1320 and the second scraper component 1420 during vertical movement. This maintains the consistency and efficiency of the scraping action even under complex or uneven crystallization conditions. As the first scraper assembly 1300 lifts and slides, the second scraper assembly 1400 moves synchronously via magnetic force. Alternatively, the second scraping assembly 1400 can drive the first scraping assembly 1300 to move up and down synchronously. Simultaneously, the first scraper 1320 and the second scraper 1420 rotate on the inner and outer walls of the inner flow pipe 1100, working together to thoroughly remove scale buildup on the pipe wall during crystallization. This mechanism of simultaneous cleaning of both inner and outer walls greatly improves the cleaning efficiency of the crystallizer, reduces the need for manual cleaning, lowers maintenance costs, and extends the equipment's operating cycle.

[0038] Furthermore, the first scraping assembly 1300 also includes a first guide member 1330, which is slidably mounted on the first scraper 1320. The first guide member 1330 is annular and has a first spiral guide groove 1331 on its outer wall. A first flow channel 1332 is formed between the outer wall of the first guide member 1330 and the inner wall of the first scraper 1320. The first guide vane 1340 has one end rotatably disposed on the inner wall of the first scraper 1320, and the other end has a first sliding part 1341. The first sliding part 1341 and the rotation axis of the first guide vane 1340 are offset in the length direction of the first guide vane 1340. The first sliding part 1341 rotates and slides in the first spiral guide groove 1331. After the first guide member 1330 moves up and down, the groove wall of the first spiral guide groove 1331 pushes the first guide vane 1340 to swing.

[0039] In this embodiment, a first guide 1330 is slidably mounted on the first scraper 1320. Firstly, the first guide 1330 and the liquid flow in the inner flow pipe 1100 cooperate to drive the sliding of the first scraper assembly 1300. In the prior art, a drive source such as a fan blade is set in the inner flow pipe 1100 to drive the liquid in the inner flow pipe 1100 and thus drive the liquid flow in the whole system. The closer the liquid is to the fan blade, the greater the flow velocity, and the farther away the liquid is from the fan blade, the smaller the flow velocity. Therefore, there are two different positional relationships of the first guide 1330 on the first scraper 1320 at the positions close to the fan blade and at the positions far away from the fan blade. The outer wall of the first guide member 1330 has a first spiral guide groove 1331, which is a spring-shaped groove with 0.1 to 0.5 turns. One end of the first guide blade 1340 is rotatably disposed on the inner wall of the first scraper 1320, and the other end is rotatably and slidably disposed in the first spiral guide groove 1331. When the first guide member 1330 and the first scraper 1320 are in a stable state before sliding, the first guide blade 1340 is inclined relative to the bottom plane of the device. That is, when the first scraper 1320 is in a position far away from the fan, the first guide blade 1340 becomes a flow guide when it is not pushed by a large water flow. On the one hand, it can drive the first scraper 1320 to rotate, and more thoroughly clean the inner wall of the inner flow pipe 1100. On the other hand, it can drive the liquid flow in the inner flow pipe 1100 to rotate. The vortex-shaped flow field helps to improve the suspension state of solid particles, promote the material transfer and mixing inside the bed, and thus achieve a better fluidization effect.

[0040] When the first guide member 1330 approaches the fan blade, it is propelled by a large water flow, causing relative sliding between the first guide member 1330 and the first scraper 1320. The groove wall of the first spiral guide groove 1331 pushes the first guide blade 1340 to swing. After swinging, the first guide blade 1340 is perpendicular to the bottom plane of the device. On the one hand, this avoids damage to the first guide blade 1340 caused by a large liquid flow velocity. On the other hand, it avoids turbulence in the inner flow cavity 1101 from affecting the crystallization production effect. Considering that the crystallization scale is more likely to exist in the location where the liquid flow velocity is slower, this design can more efficiently and fully utilize the first guide blade 1340 to drive the first scraper 1320 to rotate, so as to achieve more efficient, long-lasting and stable cleaning of the inner and outer walls of the inner flow pipe 1100.

[0041] Furthermore, the inner wall of the first scraper 1320 has a vertical second guide groove 1322, the first guide member 1330 has a second sliding part 1333, the second sliding part 1333 is slidably disposed in the second guide groove 1322, and also includes a first elastic member 1350, one end of the elastic member acts on the inner wall of the second guide groove 1322, and the other end acts on the second sliding part 1333, providing a downward force to the second sliding part 1333.

[0042] In this embodiment, a first elastic element 1350 is provided, which can keep the first scraper 1320 and the first guide 1330 from moving away from each other when the impact of the liquid flow on the first guide 1330 is small. When the first guide 1330 receives a large impact and the first scraper 1320 rises and slides, the first elastic element 1350 is compressed, causing the first guide blade 1340 to rotate. During the process of generating swirling flow, the first scraper 1320 also rotates and slides to achieve the effect of thoroughly cleaning the inner wall.

[0043] Furthermore, the second scraper assembly 1400 also includes a second guide vane 1430, which is oscillatingly disposed on the outer wall of the second scraper 1420. Both the first guide vane 1340 and the second guide vane 1430 have an arc-shaped bevel 1431. The second guide member 1440 is slidably mounted on the outer wall of the second scraper 1420. The second guide member 1440 is annular and has a stop 1441. The second guide blade 1430 has an arc-shaped guide surface 1432. The stop 1441 and the arc-shaped guide surface 1432 abut against each other. After the second guide member 1440 slides downward on the second scraper 1420, the stop 1441 pushes the second guide blade 1430 to swing. The guide wheel 1450 is rotatably mounted on the second guide member 1440 and abuts against the outer wall of the inner flow pipe 1100. The energy storage coil spring 1460 has one end mounted on the guide wheel 1450 and the other end mounted on the shaft of the guide wheel 1450, providing the force for the rotation of the guide wheel 1450.

[0044] In this embodiment, a second guide vane 1430 and a second guide member 1440 are provided on the second scraping assembly 1400. The second guide member 1440 is disposed on the outer wall of the second scraper 1420. The power for the lifting and lowering movement of the second scraper 1420 comes from the synchronous sliding caused by the power series connection between the first magnetic member 1310 and the second magnetic member 1410. The second guide vane 1430 is oscillatingly disposed on the outer wall of the second scraper 1420. The second guide vane 1430 has a similar function to the first guide vane 1340. On the one hand, it enables the second scraper 1420 to rotate and slide on the outer wall of the inner flow pipe 1100, which can more thoroughly clean the outer wall of the inner flow pipe 1100. On the other hand, it can generate swirling flow to promote crystal precipitation. The second guide vane 1430 is also rotatable. During the process of the second magnetic component 1410 being driven to rise and slide by the first magnetic component 1310, the stop 1441 of the second guide component 1440 and the arc-shaped guide surface 1432 of the second guide vane 1430 come into contact and push the second guide vane to swing.

[0045] A guide wheel 1450 is also provided on the second guide member 1440, and a power-storing coil spring 1460 is provided on the guide wheel 1450. The power source for the rise of the first scraping component 1300 and the second scraping component 1400 is the liquid flow in the inner flow pipe 1100 that drives the first scraping component 1300 and transmits it to the second scraping component 1400 through a magnetic component. During the synchronous upward sliding process of the two, the guide wheel 1450 rolls and abuts against the outer wall of the outer flow cylinder 1200, and the power-storing coil spring 1460 stores power. When the first scraping component 1300 is far away from the fan blade that generates the liquid flow, and the force received by the first scraping component 1300 is weakened, the power-storing spring releases the power. At this time, the first guide blade 1340 turns into a vertical state, so that the resistance received by the first scraping component 1300 when it slides down is minimized. This forms a set of lifting and reciprocating motion system, which can make fuller use of the power inside the device and can also form a better cleaning effect on the inner and outer walls of the inner flow pipe 1100. Both sides of the first guide vane 1340 and the second guide vane 1430 have arc-shaped bevels 1431. The arc-shaped bevels 1431 allow the fan blades to maintain the maximum area while swinging freely in the space between the two annular components. This maximizes the use of the device space and avoids the impact of the first scraper assembly 1300 and the second scraper assembly 1400 on the stability of the normal production crystallization process of this device.

[0046] This embodiment also proposes a processing technology for low-temperature sodium precipitation in the production of lithium hydroxide, which utilizes the equipment described above to perform low-temperature sodium precipitation during the lithium hydroxide production process.

[0047] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A device for producing sodium from lithium hydroxide at low temperature, characterized in that, include: Cooling water precooler (1). A primary refrigeration heat exchanger (2) is provided, and the cooling water precooler (1) is connected to the primary refrigeration heat exchanger (2). A primary cryogenic crystallizer (3) has a first liquid inlet (301) at the top and a first liquid outlet (302) at the bottom. The primary cryogenic heat exchanger (2) is connected to the first liquid inlet (301). The first stage thickener (4) has the first liquid outlet (302) leading to the first stage thickener (4). A primary centrifuge (5) is connected to the primary thickener (4). Primary mother liquor tank (6), the primary centrifuge (5) is connected to the primary mother liquor tank (6); Also includes: Secondary refrigeration heat exchanger (7), the primary mother liquor tank (6) is connected to the secondary refrigeration heat exchanger (7). The secondary cryogenic crystallizer (8) has a second liquid inlet (801) at the top and a second liquid outlet (802) at the bottom, and the secondary cryogenic heat exchanger (7) is connected to the second liquid inlet (801). Secondary thickener (9), the second liquid outlet (802) leads to the secondary thickener (9). Secondary centrifuge (10), the secondary thickener (9) leads to the secondary centrifuge (10). Secondary mother liquor tank (11), the secondary centrifuge (10) is connected to the secondary mother liquor tank (11); Both the primary cryo-crystallizer (3) and the secondary cryo-crystallizer (8) include: An internal flow tube (1100) has an internal flow cavity (1101) for upward flow of solution. An external flow tube (1200) and an internal flow tube (1100) form an external flow cavity (1201). The upper end of the internal flow cavity (1101) is connected to the upper end of the external flow cavity (1201), and the lower end of the internal flow cavity (1101) is connected to the lower end of the external flow cavity (1201). The external flow tube (1200) has an inlet at the top and an outlet at the bottom. The first wall scraping assembly (1300) is slidably mounted on the inner wall of the inner flow pipe (1100). The second wall scraping assembly (1400) is slidably mounted on the outer wall of the inner flow pipe (1100) and located inside the outer flow cavity (1201); The first scraper assembly (1300) includes: A first magnetic element (1310) is slidably mounted on the inner wall of the inner flow pipe (1100), and the first magnetic element (1310) is annular. The first scraper (1320) is rotatably mounted on the first magnetic component (1310). The rotation axis of the first scraper (1320) is the same as the axis of the inner flow pipe (1100). The first scraper (1320) has a first scraping part (1321) that abuts against the inner wall of the inner flow pipe (1100). The second scraper assembly (1400) includes: The second magnetic component (1410) is slidably mounted on the outer wall of the inner flow pipe (1100). The second magnetic component (1410) is annular. The first magnetic component (1310) and the second magnetic component (1410) are magnetically attracted to each other. The first magnetic component (1310) or the second magnetic component (1410) slides synchronously after sliding. The second scraper (1420) is rotatably mounted on the second magnetic component (1410). The rotation axis of the first scraper (1320) is the same as that of the second scraper (1420). The second scraper (1420) has a second scraping part (1421) that abuts against the outer wall of the inner flow pipe (1100). Both the first scraping part (1321) and the second scraping part (1421) have a notch (1422). The first scraper assembly (1300) further includes: The first guide member (1330) is slidably mounted on the first scraper (1320). The first guide member (1330) is annular and has a first spiral guide groove (1331) on its outer wall. A first flow channel (1332) is formed between the outer wall of the first guide member (1330) and the inner wall of the first scraper (1320). The first guide vane (1340) has one end rotatably disposed on the inner wall of the first scraper (1320), and the other end has a first sliding part (1341). The first sliding part (1341) and the rotation axis of the first guide vane (1340) are offset in the length direction of the first guide vane (1340). The first sliding part (1341) rotates and slides in the first spiral guide groove (1331). After the first guide member (1330) moves up and down, the groove wall of the first spiral guide groove (1331) pushes the first guide vane (1340) to swing.

2. The equipment for producing low-temperature sodium from lithium hydroxide according to claim 1, characterized in that, Also includes: Mother liquor precooler (12), the secondary mother liquor tank (11) is connected to the mother liquor precooler (12), the mother liquor precooler (12) is heat exchanged with the cooling water precooler (1), wherein the primary thickener (4) and the secondary thickener (9) both have overflow ports (401).

3. The equipment for producing low-temperature sodium from lithium hydroxide according to claim 1, characterized in that, The inner wall of the first scraper (1320) has a vertical second guide groove (1322), and the first guide member (1330) has a second sliding part (1333), which is slidably disposed in the second guide groove (1322). The first guide member (1330) also includes: The first elastic element (1350) acts on the inner wall of the second guide groove (1322) at one end and on the second sliding part (1333) at the other end, providing the second sliding part (1333) with a downward force.

4. The equipment for producing low-temperature sodium from lithium hydroxide according to claim 1, characterized in that, The second scraper assembly (1400) also includes: The second guide vane (1430) is oscillatingly disposed on the outer wall of the second scraper (1420). Both the first guide vane (1340) and the second guide vane (1430) have arc-shaped bevels (1431). The second guide member (1440) is slidably mounted on the outer wall of the second scraper (1420). The second guide member (1440) is annular and has a stop (1441). The second guide blade (1430) has an arc-shaped guide surface (1432). The stop (1441) and the arc-shaped guide surface (1432) abut against each other. After the second guide member (1440) slides downward on the second scraper (1420), the stop (1441) pushes the second guide blade (1430) to swing. A guide wheel (1450) is rotatably mounted on the second guide member (1440) and abuts against the outer wall of the inner flow pipe (1100). A power-storing coil spring (1460) is provided at one end on the guide wheel (1450) and at the other end on the shaft of the guide wheel (1450), providing the force for the rotation of the guide wheel (1450).

5. A processing technology for producing sodium from lithium hydroxide at low temperature, characterized in that, Low-temperature sodium precipitation during the lithium hydroxide production process using the equipment of any one of claims 1 to 4.

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