Crystallizer

Abstract

The utility model relates to a crystallizer which comprises a first shell and a first feeding pipe, a first stirring mechanism and a first layered filtering piece are arranged in the first shell, the first layered filtering piece is obliquely arranged, and an inner cavity of the first shell is divided into an upper cavity and a lower cavity which are distributed up and down by the first layered filtering piece; the outlet end of the first feeding pipe is positioned in the upper chamber; and the first shell is provided with a first discharge port which is communicated with the lower cavity and can be opened and closed. The grain size of the crystal nucleus prepared by the crystallizer is ideal and stable, and a good foundation is laid for further growing and preparing crystal products with more uniform grain size distribution.

Description

Technical Field

[0001] This utility model relates to a crystallizer, belonging to the field of crystallization equipment, particularly to the field of battery raw material preparation equipment, and especially to a crystallizer for an intermittent crystallization system. Background Technology

[0002] Lithium carbonate is chemically stable, exhibiting high thermal and electrochemical stability. It remains stable over a wide temperature range and is one of the important basic industrial salts, widely used in lithium-ion battery materials, ceramics, glass, and other industrial fields. In recent years, with the rise of the new energy market, especially the rapid development of the new energy vehicle industry, the demand for battery-grade lithium carbonate has increased significantly, driving rapid growth in lithium carbonate production. The production process of lithium carbonate mainly includes lithium extraction from salt lake brine, lithium ore, spent lithium batteries, and other lithium-containing waste materials (such as spent aluminum electrolytes and lithium-containing glass). Typically, the lithium-containing solution obtained through pretreatment is purified to remove impurities, and then lithium carbonate is obtained through carbonate precipitation. Currently, the main lithium carbonate products include industrial-grade lithium carbonate and battery-grade lithium carbonate. Compared with industrial-grade lithium carbonate, battery-grade lithium carbonate requires a purity of no less than 99.5 wt%, and has strict control over impurities that affect battery performance, such as sodium, iron, copper, and aluminum, as well as particle size distribution. In terms of particle size, the D50 is generally required to be 1.0 μm, 3 μm ≤ D90 ≤ 8 μm, and 9 μm ≤ D95 ≤ 15 μm. Therefore, the production process of battery-grade lithium carbonate has more stringent process control conditions in the lithium deposition stage.

[0003] Based on production operation characteristics, lithium carbonate crystallization processes can be divided into continuous crystallization and intermittent crystallization. Continuous lithium carbonate crystallization allows for continuous feeding and discharging, with uninterrupted production, enabling large-scale production. However, due to the dynamic entry and exit of materials, the concentration and temperature differences within the crystallization system, as well as the crystal nucleation and growth processes, are difficult to control uniformly. This not only demands high levels of technical skill and experience from operators but also makes it difficult to obtain lithium carbonate crystals that meet the required particle size. Intermittent lithium carbonate crystallization is relatively simpler to operate and requires less skilled operators, but it suffers from low production efficiency, numerous influencing factors, strong parameter control coupling, and large batch-to-batch product variations. It is difficult to consistently obtain battery-grade lithium carbonate that meets the corresponding particle size requirements, resulting in a low yield of qualified products.

[0004] Furthermore, existing crystallizers (such as CN218608114U) are prone to localized slow-flow zones, stagnant zones, and supersaturated zones in the crystallization region. This results in some areas being unable to effectively participate in the crystallization process or forming localized bursts of nucleation, ultimately leading to poor uniformity in product particle size distribution. Meanwhile, using traditional high-temperature steam heat exchange or heating methods is problematic because the heat exchange interface is a high-temperature region. Chloride ions are highly corrosive at high temperatures, easily causing corrosion damage to the heat exchange interface, affecting heat exchange efficiency and production progress. Moreover, steam heat exchange is indirect, easily creating a temperature difference between the heat exchange surface and the interior of the crystallization system, which is detrimental to the uniformity of the crystallization process and results in poor heat exchange performance, making it difficult to consistently obtain lithium carbonate crystals with narrow particle size distribution, uniform particle size, and excellent morphology.

[0005] In the preparation of lithium carbonate crystals, it is often necessary to first prepare a nucleus slurry, and then control the growth of the nuclei to form lithium carbonate crystal products with the desired particle size and morphology (e.g., CN119370870A). The size uniformity of the nuclei in the nucleus slurry has a significant impact on the particle size uniformity of the lithium carbonate crystal products formed in subsequent nucleus growth processes. Therefore, it is necessary to develop crystallization equipment to achieve the preparation of high-quality nuclei. Utility Model Content

[0006] In view of the shortcomings of the existing technology, one of the objectives of this utility model is to provide a crystallizer that can be used to prepare crystal nuclei with good particle size distribution.

[0007] To solve the above-mentioned technical problems, the technical solution of this utility model is as follows:

[0008] A crystallizer includes a first shell and a first feed pipe. The first shell is provided with a first stirring mechanism and a first layered filter element. The first layered filter element is inclined and divides the inner cavity of the first shell into an upper chamber and a lower chamber. The outlet end of the first feed pipe is located in the upper chamber. The first shell is provided with a first discharge port that communicates with the lower chamber and can be opened and closed.

[0009] Therefore, the first layered filter element is inclined. On the one hand, under the influence of gravity, the first layered filter element can screen the crystal nuclei generated in the upper chamber. Oversized crystal nuclei are trapped in the upper chamber, while smaller crystal nuclei enter the lower chamber, which helps to better control the crystal nuclei size. On the other hand, the inclined first layered filter element is larger in size, and under the disturbance of liquid flow, it is more likely to generate vibration, which helps to strengthen the above screening process and reduce the possibility of filter pore blockage. This helps to make the crystallizer move more stably and smoothly, and obtain crystal nuclei with ideal and stable particle size, laying a good foundation for subsequent growth to obtain crystal products with more uniform particle size distribution.

[0010] This effectively ensures the particle size of the crystal nuclei entering subsequent steps, preparing for the bimodal distribution of particle size in crystalline products such as lithium carbonate; it also helps to increase the amount of crystal nuclei generated in the crystallizer, preparing for a larger output of crystalline products in the crystallizer, thus improving overall efficiency.

[0011] Furthermore, it also includes a first air inlet pipe, the outlet of which is located in the upper chamber. Thus, a gas carrying thermally stable heat and with a small temperature difference from the target temperature (such as heat-carrying air, heat-carrying inert gas, etc.) can be introduced into the crystallizer through the first air inlet pipe to directly heat the crystallization reaction system. Simultaneously, during the mixing and crystallization process, mechanical stirring can be applied by the first stirring mechanism. Combined with the disturbance effect of the introduced gas, this helps to form multi-directional turbulence in the gas-liquid mixture. Heat exchange can then occur directly under multi-directional turbulence, resulting in high heat exchange efficiency and a stable and uniform heat exchange process. This allows for more effective control of the nucleation process, number of nuclei, and nucleation size during the burst nucleation phase.

[0012] Furthermore, the angle between the discharge direction at the outlet end of the first feed pipe and the gas discharge direction at the outlet end of the first gas inlet pipe is 30-150°, preferably 60-120°. Thus, the low-temperature differential gas input through the first feed pipe (the temperature of the gas can be dynamically adjusted so that the gas temperature is slightly higher than the system temperature to maintain heat balance) can form a countercurrent turbulence with the liquid input through the first feed pipe. The gas-liquid mixture directly exchanges heat and transfers mass under multi-directional turbulent flow, resulting in high mass and heat transfer efficiency and a more stable and uniform process. This helps to more effectively control the nucleation process, number of nuclei, and nucleation size during the nucleation phase.

[0013] Furthermore, the distance between the vertical projection of the outlet end of the first feed pipe on the first layered filter element and the lowest point of the first layered filter element is less than the distance between the vertical projection and the highest point of the first layered filter element.

[0014] The distance between the vertical projection of the outlet end of the first intake pipe onto the first layered filter and the lowest point of the first layered filter is less than the distance between the vertical projection and the highest point of the first layered filter.

[0015] The vertical projection of the outlet end of the first air inlet pipe onto the first layered filter element is lower than the vertical projection of the outlet end of the first feed pipe onto the first layered filter element. Therefore, both the outlet ends of the first feed pipe and the first air inlet pipe are closer to the lower end of the first layered filter element. Furthermore, the outlet end of the first air inlet pipe is located outside the outlet end of the first feed pipe. The gas input through the first air inlet pipe can effectively impact and heat the fresh liquid input through the first feed pipe, resulting in more thorough mixing of the fresh liquid with the existing liquid, which is beneficial for the crystallization reaction. Preferably, as one embodiment, the outlet end of the first air inlet pipe is provided with a rotatable nozzle.

[0016] Furthermore, the outlet end of the first air inlet pipe is located lower than the outlet end of the first feed pipe, thereby improving the impact effect of the gas input into the first air inlet pipe on the liquid material input into the first feed pipe.

[0017] Optionally, the angle between the first layered filter element and the horizontal direction is 15-75°, preferably 30-60°.

[0018] Optionally, the vertical distance between the outlet end of the first feed pipe and the first layered filter element is 8-16cm, further 10-14cm, and the vertical distance between the outlet end of the first air inlet pipe and the first layered filter element is 2-10cm, further 4-8cm.

[0019] Furthermore, the discharge direction of the first feed pipe's outlet end intersects with the air outlet direction of the first air inlet pipe's outlet end, thereby causing the resulting liquid flow and airflow to collide and impact each other, further enhancing the impact effect.

[0020] Furthermore, the outlet end of the first intake pipe faces the first layered filter element, which can better disperse the deposits on the first layered filter element.

[0021] Furthermore, the height of the outlet end of the first air intake pipe is located between the highest and lowest points of the first layered filter element. As a result, the air force input by the first air intake pipe can generate a stronger impact and disturbance on the first layered filter element, which helps to reduce the possibility of crystal nuclei depositing on the first layered filter element or clogging the filter pores.

[0022] Furthermore, a first vibrating plate extending upward is fixed to the top of the first layered filter element. The first vibrating plate is positioned opposite to the outlet end of the first air inlet pipe. More preferably, the width of the first vibrating plate is smaller than the diameter of the outlet end of the first air inlet pipe. More preferably, the thickness of the first layered filter element is 0.5-3 mm, and even more preferably, 1-2.5 mm, while the thickness of the first vibrating plate is 1-5 mm, and even more preferably, 2-4 mm. By setting the first vibrating plate at the above-mentioned position, the airflow can impact the first vibrating plate during air intake, thereby driving the first layered filter element to vibrate more strongly, thus improving the sieving effect of the first layered filter element and better preventing excessive deposition of crystal nuclei or clogging of the filter pores on the first layered filter element.

[0023] Furthermore, the crystallizer also includes a third air inlet pipe, the outlet end of which is located in the upper chamber. The distance between the vertical projection of the outlet end of the third air inlet pipe on the first layered filter and the highest point of the first layered filter is less than the distance between the vertical projection and the lowest point of the first layered filter. More preferably, as one embodiment, the angle between the air outlet direction of the third air inlet pipe and the tilt direction of the first layered filter is 0-120°; more preferably, as another embodiment, the outlet end of the third air inlet pipe is provided with a rotatable nozzle.

[0024] This not only further optimizes the overall gas-liquid mixing turbulent heat transfer, thereby reducing or eliminating the adverse factors affecting uniform nucleation such as temperature and concentration differences, but also helps to disperse the deposits on the first layered filter element, ensuring that fine crystal nuclei can pass smoothly through the first layered filter element into the lower chamber.

[0025] Furthermore, the crystallizer also includes a first exhaust pipe communicating with the first housing;

[0026] And / or, the crystallizer further includes a first exhaust pipe and a first indirect heat exchanger connected to the first shell, the first exhaust pipe being connected to a medium inlet of the first indirect heat exchanger, and the first inlet pipe being connected to the medium outlet of the first indirect heat exchanger. Thus, not only can the waste heat of the gas discharged from the crystallizer be utilized, reducing gas consumption, but the stability of the internal gas pressure of the mixing crystallizer can also be ensured.

[0027] Furthermore, the layered filter element is a filter screen or filter plate, and the size of the filter pores on the first layered filter element is 270 mesh or larger.

[0028] Furthermore, the first air intake pipe is equipped with an external air source interface to facilitate the replacement of the introduced gas and / or the adjustment of gas flow rate, temperature, etc.

[0029] Furthermore, a heat exchange jacket is provided outside the first housing. By using the jacket in conjunction with the gas input through the relevant air inlet pipe, it helps to further optimize the efficient and low-temperature differential heat exchange process of the mixing crystallizer and obtain a more uniform temperature field.

[0030] Further, the first stirring mechanism includes a first stirrer and a second stirrer. The first stirrer is disposed in the upper chamber and includes a first shaft and a plurality of first stirring blades disposed on the first shaft. The second stirrer is disposed in the lower chamber and includes a second shaft and a plurality of second stirring blades disposed on the second shaft. Preferably, the angle between the central axis of the first shaft and the central axis of the second shaft is 45-135°. More preferably, the central axis of the first shaft and the central axis of the second shaft are located in different or the same vertical plane. Preferably, the plurality of first stirring blades are distributed sequentially along the length direction of the first shaft, and the lengths of the first stirring blades at different positions along the length direction of the first shaft are the same or different. Preferably, the plurality of second stirring blades are distributed sequentially along the length direction of the second shaft, and the lengths of the second stirring blades at different positions along the length direction of the second shaft are the same or different. Optionally, the number of second stirrers is at least two, and they are distributed sequentially along the horizontal direction.

[0031] Therefore, by forming agitators and / or unequal-length impellers at specific angles between the upper and lower chambers along their axial directions, the turbulence of the system is enhanced in conjunction with the airflow, which helps to improve the system uniformity during the crystallization process, break the volume agglomeration of crystal grains during the explosive nucleation period, and prevent excessively coarse crystal nuclei entering the lower chamber. Furthermore, the first layered filter element can be disturbed simultaneously from above and below, which helps to prevent the accumulation of large amounts of deposits on (and within) the first layered filter element during operation, thus avoiding the formation of two practically independent chambers in the upper and lower chambers. This further improves the temperature and concentration uniformity of the upper and lower chambers, resulting in high-quality crystal nucleation slurry. By setting the central axes of the first and second axes in different vertical planes, and by arranging several second agitators along the horizontal direction of the crystallizer, the system turbulence in the nucleation section is further enhanced, while preventing crystal deposition at the bottom of the crystallizer.

[0032] Furthermore, the crystallizer also includes a first circulation pipe, through which the lower chamber and the upper chamber are connected. The first circulation pipe is equipped with a first pump for pumping the slurry from the lower chamber into the upper chamber. This allows for enhanced turbulent mixing during the mixing and crystallization stage while ensuring the appropriate grain size for the subsequent crystallization and separation stage.

[0033] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0034] (1) The crystal nuclei prepared by the crystallizer of this utility model have ideal and stable particle size, which lays a good foundation for further growth and preparation of crystallized products with narrow particle size distribution, good particle uniformity and high yield of qualified products.

[0035] (2) The first sheet filter element in the crystallizer of this utility model is inclined, which makes it less prone to clogging, helps the crystallizer to operate stably for a long time, and facilitates industrial production. Attached Figure Description

[0036] Figure 1 This is a simplified structural diagram of the crystallizer according to Embodiment 1 of this utility model.

[0037] Figure 2 This is a simplified structural diagram of the crystallization system of Embodiment 1 of this utility model.

[0038] Figure 3 This is a simplified structural diagram of the crystallizer of Embodiment 1 of this utility model.

[0039] Figure 4 This is a side view showing the positional relationship between the first circulation tube and the first shell in the crystallizer of Embodiment 1 of this utility model.

[0040] Figure 5 This is a top view showing the positional relationship between the second circulation pipe and the second shell in the crystallizer of Embodiment 1 of this utility model.

[0041] Figure 6 This is a side view showing the positional relationship between the second circulation pipe and the second shell in the crystallizer of Embodiment 1 of this utility model.

[0042] Figure 7 This is a particle size distribution diagram of the lithium carbonate product obtained in Example 1 of this utility model.

[0043] Figure 8 This is a simplified structural diagram of the crystallizer according to Embodiment 2 of this utility model.

[0044] Figure 9 This is a simplified structural diagram of the crystallizer of Embodiment 2 of this utility model. Detailed Implementation

[0045] The present invention will be described in detail below with reference to the embodiments. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other. For ease of description, the words "up," "down," "left," and "right" appearing below only indicate that they are consistent with the up, down, left, and right directions of the drawings themselves, and do not limit the structure.

[0046] Example 1

[0047] See Figure 1A crystallizer 1 includes a first housing 1-1 and a first feed pipe 1-3. The first housing 1-1 is provided with a first stirring mechanism and a first layered filter element 1-6. The first layered filter element 1-6 is inclined at a 30° angle to the horizontal direction and divides the inner cavity 1-2 of the first housing 1-1 into an upper chamber 1-2-1 and a lower chamber 1-2-2. The outlet end of the first feed pipe 1-3 is located in the upper chamber 1-2-1. The first housing 1-1 is provided with a first discharge port 1-7 that communicates with the lower chamber 1-2-2 and can be opened and closed.

[0048] It also includes a first air inlet pipe 1-4, the outlet end of which is located in the upper chamber 1-2-1. The vertical distance between the outlet end of the first feed pipe 1-3 and the first layered filter element 1-6 is 12cm, and the vertical distance between the outlet end of the first air inlet pipe 1-4 and the first layered filter element is 6cm.

[0049] The angle between the discharge direction of the first feed pipe 1-3 and the air discharge direction of the first air inlet pipe 1-4 is 90°.

[0050] The distance between the vertical projection of the outlet end of the first feed pipe 1-3 on the first layered filter element 1-6 and the lowest point of the first layered filter element 1-6 is less than the distance between the vertical projection and the highest point of the first layered filter element 1-6.

[0051] The distance between the vertical projection of the outlet end of the first intake pipe 1-4 on the first layered filter element 1-6 and the lowest point of the first layered filter element 1-6 is less than the distance between the vertical projection and the highest point of the first layered filter element 1-6.

[0052] The position of the vertical projection of the outlet end of the first air inlet pipe 1-4 on the first layered filter element 1-6 is lower than the position of the vertical projection of the outlet end of the first feed pipe 1-3 on the first layered filter element 1-6.

[0053] The outlet end of the first air inlet pipe 1-4 is located lower than the outlet end of the first feed pipe 1-3;

[0054] The discharge direction (vertically downward) of the outlet end of the first feed pipe 1-3 intersects the air discharge direction (horizontally to the left, toward the central axis of the first housing) of the outlet end of the first air inlet pipe 1-4.

[0055] The outlet end of the first air intake pipe 1-4 faces the first layered filter element 1-6;

[0056] The height of the outlet end of the first air intake pipe 1-4 is between the highest and lowest points of the first layered filter element 1-6.

[0057] The layered filter element is a filter plate, and the filter pore size on the first layered filter element is 270 mesh.

[0058] The first stirring mechanism includes a first stirrer 1-10 and a second stirrer 1-11. The first stirrer 1-10 is disposed in the upper chamber 1-2-1 and includes a first shaft and a plurality of first stirring blades disposed on the first shaft. The second stirrer 1-11 is disposed in the lower chamber 1-2-2 and includes a second shaft and a plurality of second stirring blades disposed on the second shaft.

[0059] See Figure 4 The crystallizer 1 further includes a first circulation pipe, through which the lower chamber and the upper chamber are connected. The first circulation pipe is equipped with a first pump for pumping the slurry from the lower chamber into the upper chamber.

[0060] The first heat exchange jacket 1-13 is provided outside the first housing.

[0061] See Figures 2-3 The applicant has independently developed a crystallization system, which includes a crystallizer 1, a first valve 3, a third pump 4, a crystallizer separator 2, a second valve 5, and a fourth pump 6.

[0062] The crystallization separator 2 includes a second shell 2-1, a second feed pipe 2-3, and a second air inlet pipe 2-4. The second feed pipe 2-3 is connected to the first outlet 1-7. The second shell 2-1 is equipped with a second stirring mechanism, a second layered filter element 2-6, and a third layered filter element 2-7. The second layered filter element 2-6 and the third layered filter element 2-7 are both inclined, and are parallel to each other and at a 45° angle to the horizontal plane. The second layered filter element 2-6 and the third layered filter element 2-7 are distributed vertically, dividing the inner cavity of the second shell 2-1 into a first chamber, a second chamber, and a third chamber, which are distributed from top to bottom. The first chamber consists of three chambers. The outlet ends of the second feed pipe 2-3 and the second air inlet pipe 2-4 are both located within the first chamber. The vertical distance between the outlet end of the second feed pipe 2-3 and the second layered filter element 2-6 is 8 cm, and the vertical distance between the outlet end of the second air inlet pipe 2-4 and the second layered filter element is 6 cm. The second housing 2-1 has a second discharge port 2-8 that communicates with the second chamber and is openable and closable. The second discharge port 2-8 has a sealing door for easy opening and closing. The second discharge port 2-8 is located at the junction of the lowest point of the second layered filter element 2-6 and the second housing 2-1. The bottom of the second housing 2-1 has a third discharge port 2-9 that communicates with the third chamber. A second heat exchange jacket is provided outside the second housing.

[0063] The first discharge port 1-7, the first valve 3, the third pump 4, the second feed pipe 2-3, the third discharge port 2-9, and the fourth pump 6 are connected in sequence, and the outlet of the fourth pump 6 is connected to the first feed pipe 1-3.

[0064] The angle between the discharge direction (vertically downward) of the outlet end of the second feed pipe 2-3 and the air discharge direction (horizontally to the left, toward the central axis of the first housing) of the outlet end of the second air inlet pipe 2-4 is 90°.

[0065] The outlet end of the second feed pipe 2-3 is located above the second layered filter element 2-6. The distance between the vertical projection of the outlet end of the second feed pipe 2-3 on the second layered filter element 2-6 and the lowest point of the second layered filter element 2-6 is less than the distance between the vertical projection and the highest point of the second layered filter element 2-6.

[0066] The outlet end of the second air intake pipe 2-4 is located above the second layered filter element 2-6. The distance between the vertical projection of the outlet end of the second air intake pipe 2-4 on the second layered filter element 2-6 and the lowest point of the second layered filter element 2-6 is less than the distance between the vertical projection and the highest point of the second layered filter element 2-6.

[0067] The position of the vertical projection of the outlet end of the second air inlet pipe 2-4 on the second layered filter element 2-6 is lower than the position of the vertical projection of the outlet end of the second feed pipe 2-3 on the second layered filter element 2-6.

[0068] The outlet end of the second air inlet pipe 2-4 is located lower than the outlet end of the second feed pipe 2-3;

[0069] The discharge direction of the outlet end of the second feed pipe 2-3 intersects with the air discharge direction of the outlet end of the second air inlet pipe 2-4;

[0070] The outlet end of the second air intake pipe 2-4 faces the second layered filter element 2-6; the height of the outlet end of the second air intake pipe 2-4 is between the highest point and the lowest point of the second layered filter element 2-6.

[0071] The filter pores on the first layer filter element are 270 mesh; the filter pores on the second layer filter element are 120 mesh; the filter pores on the third layer filter element are 270 mesh; each layer filter element is a flat plate filter plate with uniformly distributed filter pores.

[0072] The second stirring mechanism includes a third shaft and a plurality of third stirring blades. The third shaft passes rotatably through the second layered filter element 2-6 and the third layered filter element 2-7 from top to bottom via rubber-sealed deep groove ball bearings and extends into the third chamber. The plurality of third stirring blades are distributed sequentially along the length of the third shaft.

[0073] See Figure 5 and Figure 6 The crystallizer 2 further includes a second circulation pipe 2-11. The second chamber and the third chamber are connected to the first chamber through the second circulation pipe 2-11. The second circulation pipe 2-11 is provided with a second pump 2-15 for pumping the liquid from the second chamber and the third chamber into the first chamber.

[0074] In the crystallizer described above, the second and third layered filter elements are arranged at an angle. On the one hand, under the influence of gravity, they can screen the lithium carbonate crystals of different particle sizes. On the other hand, the larger size of the inclined second and third layered filter elements makes them more prone to larger vibrations under the disturbance of liquid and air flow, which helps to enhance the screening process and reduce the possibility of clogging of the filter pores of the second and third layered filter elements. This helps to make the crystallizer move more stably and smoothly, and obtain lithium carbonate products with ideal and stable particle size distribution.

[0075] The method for crystallizing lithium carbonate using the crystallization system described above includes the following steps:

[0076] S1. A lithium salt (lithium chloride) solution is introduced into the first housing 1-1 through the first feed pipe 2-3. The first stirring mechanism is turned on, and then a heat transfer gas (hot air) is introduced into the first housing 1-1 to heat it to a preset temperature (first crystallization temperature). Then, a sodium carbonate solution is introduced into the first housing 1-1 through the first feed pipe 2-3. During this process, the first pump located on the first circulation pipe is started, and the heat transfer gas is continuously introduced to maintain the first crystallization temperature and carry out the first-order crystallization reaction to obtain the first crystallization slurry.

[0077] S2. The first crystallization slurry is fed into the second housing 2-1 through the second feed pipe 2-3. The second stirring mechanism is turned on and heat carrier gas (hot air) is introduced into the second housing 2-1. During this period, the second pump 2-15 located on the second circulation pipe 2-11 is started to continuously introduce heat carrier gas. After the second crystallization temperature is maintained and the second crystallization reaction is carried out, the slurry in the second housing 2-1 is discharged through the third discharge port 2-9. Then the second discharge port 2-8 is opened to discharge the lithium carbonate product on the third layered filter element 2-7 to the outside of the second housing 2-1.

[0078] The particle size distribution of the obtained lithium carbonate product is shown in the figure below. Figure 7 As shown in the figure, the obtained lithium carbonate product has a narrow particle size distribution, all concentrated in the range of 55-113μm, of which the particle size of 100±10μm accounts for more than 75%, with good uniformity. Moreover, the lithium carbonate product deposited on the third layer filter accounts for more than 95% of the total crystallization.

[0079] It is evident that the crystallization system with the aforementioned crystallizer is well-suited for the preparation of lithium carbonate crystallized products. Adapted to the characteristics of lithium carbonate crystallization, the system separates the lithium carbonate crystallization process into two stages: mixed crystallization (conducted within the crystallizer) and crystallization separation (conducted within the crystallizer separator). By utilizing gas-liquid heat exchange, mechanical shearing, multi-directional turbulence, and grain sieving control, the sodium carbonate crystallization process is optimized synergistically, ultimately yielding lithium carbonate products with uniform particle size distribution, stable crystal clusters, minimal agglomeration, and few impurities. The intermittent crystallization reaction of lithium carbonate using this system is beneficial for obtaining high-purity, high-quality battery-grade lithium carbonate products.

[0080] Example 2

[0081] Repeat Example 1, except that: see Figure 8 The top of the first layered filter element 1-6 is fixed with an upwardly extending first vibrating plate 1-12. The first vibrating plate 1-12 is disposed opposite to the outlet end of the first air inlet pipe 1-4. The width of the first vibrating plate 1-12 is smaller than the diameter of the outlet end of the first air inlet pipe 1-4. The thickness of the first layered filter element 1-6 is 1 mm, and the thickness of the first vibrating plate 1-12 is 1.5 mm.

[0082] See Figure 9 The top of the second layered filter element 2-6 is fixed with an upwardly extending second vibrating plate 2-14. The second vibrating plate 2-14 is arranged opposite to the outlet end of the second air inlet pipe 2-4. The width of the second vibrating plate 2-14 is smaller than the diameter of the outlet end of the second air inlet pipe 2-4. The thickness of the second layered filter element 2-6 is 1 mm, and the thickness of the second vibrating plate 2-14 is 1.5 mm.

[0083] Example 3

[0084] The embodiment 1 is repeated, except that an ultrasonic generator 2-12 is provided at the bottom of the second housing 2-1.

[0085] Example 4

[0086] The embodiment 1 is repeated, except that: the outlet ends of the first air inlet pipe 1-4 and the second air inlet pipe 2-4 are respectively provided with rotatable nozzles. When the rotatable nozzle rotates, the angle of rotation in the vertical plane is 0-75° with the axis of the nozzle. The angle between the outlet end of the first air inlet pipe 1-4 and the inclined direction of the first layered filter element 1-6, and the angle between the air outlet direction of the outlet end of the second air inlet pipe 2-4 and the inclined direction of the second layered filter element 2-6, change dynamically with the rotation of the rotatable nozzle.

[0087] Example 5

[0088] The embodiment 1 is repeated, except that the crystallizer 1 further includes a first exhaust pipe 1-5 and a first indirect heat exchanger 1-9 connected to the first shell 1-1. The first exhaust pipe 1-5 is connected to a medium inlet of the first indirect heat exchanger 1-9, and the first air inlet pipe 1-4 is connected to the medium outlet of the first indirect heat exchanger 1-9.

[0089] Example 6

[0090] The embodiment 1 is repeated, except that: the crystallizer 1 further includes a third air inlet pipe 1-8, the outlet end of the third air inlet pipe 1-8 is located in the upper chamber 1-2-1, the distance between the vertical projection of the outlet end of the third air inlet pipe 1-8 on the first layered filter element 1-6 and the highest point of the first layered filter element 1-6 is less than the distance between the vertical projection and the lowest point of the first layered filter element 1-6; the angle between the air outlet direction of the third air inlet pipe 1-8 and the tilt direction of the first layered filter element 1-6 is 40°.

[0091] Example 7

[0092] The embodiment 6 is repeated, except that: the outlet end of the third air inlet pipe 1-8 is provided with a rotatable nozzle, and the angle of rotation of the rotatable nozzle in the vertical plane is 0-75° with the axis of the nozzle. The angle between the air outlet direction of the third air inlet pipe 1-8 and the tilting direction of the first layered filter element 1-6 changes dynamically with the rotation of the rotatable nozzle.

[0093] Example 8

[0094] The embodiment 5 is repeated, except that the crystallizer 2 further includes a second exhaust pipe 2-5 and a second indirect heat exchanger 2-13 connected to the second shell 2-1. The second exhaust pipe 2-5 is connected to a medium inlet of the second indirect heat exchanger 2-13, and the second air inlet pipe 2-4 is connected to the medium outlet of the second indirect heat exchanger 2-13.

[0095] Example 9

[0096] The embodiment 1 is repeated, except that: the angle between the central axis of the first shaft (parallel to the vertical direction) and the central axis of the second shaft (parallel to the horizontal direction) is 90°, and the central axis of the first shaft and the central axis of the second shaft are located in the same vertical plane; the plurality of first stirring blades are evenly distributed in sequence along the length direction of the first shaft, and the length of the first stirring blades at different positions along the length direction of the first shaft is the same.

[0097] Example 10

[0098] Example 9 is repeated, except that the plurality of second stirring blades are distributed sequentially along the length of the second shaft, and the lengths of the second stirring blades at different positions along the length of the second shaft are not the same.

[0099] Example 11

[0100] Example 10 is repeated, except that the distance between the third stirring blade in the second chamber and the adjacent third stirring blade is greater than the distance between the adjacent third stirring blades in the third chamber, and the distance between the adjacent third stirring blades in the first chamber is greater than the distance between the adjacent third stirring blades in the third chamber.

[0101] Example 12

[0102] The embodiment 9 is repeated, except that the crystallizer 2 further includes a fourth air inlet pipe 2-2 that communicates with the second chamber, and the air outlet of the fourth air inlet pipe 2-2 is directed toward the central axis of the second discharge port 2-8.

[0103] The area where the second outlet 2-8 is located on the second housing 2-1 is inclined toward the third layered filter element 2-7. The air outlet direction of the fourth air inlet pipe 2-2 is parallel to the area. The outlet of the fourth air inlet pipe 2-2 is located at the junction of the area and other areas of the second housing.

[0104] The angle between the air outlet direction of the fourth air inlet pipe 2-2 and the extension line of the third layered filter element is 20°.

[0105] The above embodiments should be understood as being used only to illustrate the present invention more clearly, and not to limit the scope of the present invention. After reading the present invention, any modifications of the present invention by those skilled in the art in various equivalent forms fall within the scope defined by the appended claims.

Claims

1. A crystallizer comprising a first housing (1-1) and a first feed pipe (1-3), the first housing (1-1) being provided with a first stirring mechanism and a first layered filter member (1-6) therein, characterized in that, The first layered filter element (1-6) is inclined and divides the inner cavity of the first housing (1-1) into an upper chamber (1-2-1) and a lower chamber (1-2-2) distributed above and below; the outlet end of the first feed pipe (1-3) is located in the upper chamber (1-2-1); the first housing (1-1) is provided with a first discharge port (1-7) that communicates with the lower chamber (1-2-2) and can be opened and closed.

2. The crystallizer of claim 1, wherein It also includes a first air inlet pipe (1-4), the outlet end of which is located in the upper chamber (1-2-1).

3. The crystallizer of claim 2, wherein The angle between the discharge direction of the first feed pipe (1-3) and the air discharge direction of the first air inlet pipe (1-4) is 30-150°.

4. The crystallizer of claim 2, wherein The distance between the vertical projection of the outlet end of the first feed pipe (1-3) onto the first layered filter element (1-6) and the lowest point of the first layered filter element (1-6) is less than the distance between the vertical projection and the highest point of the first layered filter element (1-6). The distance between the vertical projection of the outlet end of the first intake pipe (1-4) onto the first layered filter (1-6) and the lowest point of the first layered filter (1-6) is less than the distance between the vertical projection and the highest point of the first layered filter (1-6). The position of the vertical projection of the outlet end of the first air inlet pipe (1-4) onto the first layered filter element (1-6) is lower than the position of the vertical projection of the outlet end of the first feed pipe (1-3) onto the first layered filter element (1-6).

5. The crystallizer of claim 4, wherein The outlet end of the first air inlet pipe (1-4) is located lower than the outlet end of the first feed pipe (1-3); And / or, the discharge direction of the outlet end of the first feed pipe (1-3) intersects with the air discharge direction of the outlet end of the first air inlet pipe (1-4); And / or, the outlet end of the first air inlet pipe (1-4) faces the first layered filter element (1-6); And / or, the height of the outlet end of the first air intake pipe (1-4) is between the highest and lowest points of the first layered filter element (1-6); And / or, the top of the first layered filter element (1-6) is fixed with an upwardly extending first vibrating plate (1-12), the first vibrating plate (1-12) being disposed opposite to the outlet end of the first air inlet pipe (1-4).

6. The crystallizer of claim 2, wherein The crystallizer (1) also includes a first exhaust pipe (1-5) communicating with the first housing (1-1); And / or, the crystallizer (1) further includes a first exhaust pipe (1-5) and a first indirect heat exchanger (1-9) communicating with the first housing (1-1), the first exhaust pipe (1-5) communicating with a medium inlet of the first indirect heat exchanger (1-9), and the first air inlet pipe (1-4) communicating with the medium outlet of the first indirect heat exchanger (1-9).

7. The crystallizer according to any one of claims 1 to 6, characterized in that The crystallizer (1) further comprises a third gas inlet pipe (1-8), an outlet end of the third gas inlet pipe (1-8) is located in the upper chamber (1-2-1), and a vertical projection of the outlet end of the third gas inlet pipe (1-8) on the first layered filter (1-6) is less than a distance between the vertical projection and a highest point of the first layered filter (1-6).

8. The crystallizer according to any one of claims 1 to 6, characterized in that The layered filter is a filter screen or a filter plate, and a size of a filter hole on the first layered filter is greater than or equal to 270 mesh.

9. The crystallizer according to any one of claims 1 to 6, characterized in that The first stirring mechanism comprises a first stirrer (1-10) and a second stirrer (1-11), the first stirrer (1-10) is arranged in the upper chamber (1-2-1), the first stirrer (1-10) comprises a first shaft and a plurality of first stirring blades arranged on the first shaft, and the second stirrer (1-11) is arranged in the lower chamber (1-2-2), the second stirrer (1-11) comprises a second shaft and a plurality of second stirring blades arranged on the second shaft.

10. The crystallizer according to any one of claims 1-6, characterized in that The crystallizer (1) further comprises a first circulation pipe, the lower chamber and the upper chamber are communicated through the first circulation pipe, and a first pump for pumping slurry in the lower chamber into the upper chamber is arranged on the first circulation pipe.

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