Continuous cooling crystallization device for recovering and extracting sodium sulfate in waste battery electrolyte

Abstract

The utility model discloses a continuous cooling crystallization device for recovering and extracting sodium sulfate in waste battery electrolyte. The continuous cooling crystallization device comprises a crystallizer shell and a crystallizer jacket, the crystallizer jacket is fixedly arranged on the outer wall of the crystallizer shell in a sleeving manner; a circulating cooling medium is introduced into the crystallizer jacket, a coaxial sleeve-shaped guide cylinder is arranged in the crystallizer shell, two layers of stirring blades are arranged in the guide cylinder, and the stirring blade at the lower layer is flush with the lower edge of the guide cylinder; one end of a first channel serving as a feeding hole of the crystallizer is positioned on the side wall of the guide cylinder, and extends out of the outer wall of the crystallizer jacket after sequentially passing through a cylinder body of the crystallizer shell and the crystallizer jacket; one end of a second channel serving as a turbidimeter and thermometer port extends into the barrel of the crystallizer shell and extends out of the outer wall of the crystallizer jacket after passing through the crystallizer jacket, and one end of a first channel located on the side wall of the guide cylinder is located between the double-layer stirring blades.

Description

Technical Field

[0001] The utility model belongs to the technical field of crystallization, and in particular relates to a continuous cooling crystallization device for recovering and extracting sodium sulfate from electrolyte of discarded batteries. Background Art

[0002] Waste lithium-ion battery electrolyte contains a large amount of sodium sulfate and lithium sulfate resources. If improperly handled, it will cause a great waste of metal resources and serious environmental pollution. Therefore, recycling waste lithium-ion batteries is crucial to recovering metal lithium resources with high added value and protecting the environment. Usually, the battery electrolyte contains a large amount of sodium sulfate and a small amount of lithium sulfate. In order to realize the resource recovery of sodium sulfate and lithium sulfate, it is necessary to first separate most of the sodium sulfate by cooling crystallization, and then separate the lithium sulfate by evaporation crystallization. At present, for the sodium sulfate cooling crystallization recovery process of this system, most of the OSLO type continuous cooling crystallizers are used, which have the advantages of large solution circulation volume, small solution supersaturation, and not easy to produce secondary nucleation. In addition, the OSLO continuous crystallizer has a particle size classification effect, which makes the sodium sulfate crystal product size larger and the particle size distribution uniform. However, the forced external circulation heat exchange form of the OSLO crystallizer is easy to cause scaling or even blockage of the heat mixing pipe, affecting the heat exchange effect and cooling crystallization efficiency, and needs to be stopped for cleaning, and the crystallization system cannot be continuously and stably operated for a long time. In addition, the OSLO cooling crystallizer has no stirring device, and dead zones are prone to occur in the solid-liquid two-phase mass transfer and heat transfer, resulting in poor mixing effects. For the lithium sulfate and sodium sulfate system of battery electrolyte, due to the high local supersaturation, lithium sulfate crystals may precipitate and be discharged together with the sodium sulfate crystal product, reducing the purity of the sodium sulfate product and affecting the resource utilization rate of lithium.

[0003] Chinese patent CN203816265U discloses a crystallizer for continuous crystallization of inorganic salts, characterized by the use of forced external circulation cooling. Since the cooling method used in the equipment is prone to scaling problems, it affects the continuous operation of the equipment to a certain extent. In addition, since there is no stirring inside the crystallizer, the slurry mixing is poor and the supersaturation is uneven, which is not conducive to the effective control of particle size and particle size distribution. Utility Model Content

[0004] In view of the shortcomings of the prior art, the utility model provides a continuous cooling crystallization device for recovering and extracting sodium sulfate from waste battery electrolyte. The continuous cooling crystallization device utilizes circulation within a guide tube to improve product purity and particle size, and can ensure long-term stable operation of the equipment.

[0005] The purpose of this utility model is achieved through the following technical solutions:

[0006] A continuous cooling crystallization device for recovering and extracting sodium sulfate from waste battery electrolyte, comprising a crystallizer shell and a crystallizer jacket; the crystallizer jacket is fixedly sleeved on the outer wall of the crystallizer shell; a circulating cooling medium is introduced into the crystallizer jacket, and a jacket medium inlet and a jacket medium outlet are provided on the outer wall of the crystallizer jacket, and the jacket medium outlet is located at a position higher than the jacket medium inlet;

[0007] A coaxial sleeve-shaped guide tube is arranged inside the crystallizer shell, a stirring motor is arranged on the top, and two layers of stirring blades are arranged at the bottom of the stirring motor. Both layers of stirring blades are located inside the guide tube, and the lower layer of stirring blades is flush with the lower edge of the guide tube;

[0008] One end of a first channel is located on the side wall of the guide tube, and passes through the crystallizer shell body and the crystallizer jacket in sequence and then extends out of the outer wall of the crystallizer jacket. The other end of the first channel serves as a crystallizer feed port for directly adding materials into the guide tube;

[0009] One end of a second channel extends into the crystallizer shell body and is 0.1-0.5m away from the outer wall of the guide tube, and extends out of the outer wall of the crystallizer jacket after passing through the crystallizer jacket. The other end of the second channel serves as a turbidity meter and a thermometer port for inserting the turbidity meter and the thermometer to detect the crystallization process;

[0010] Moreover, one end of the first channel on the side wall of the guide tube is located between the double-layer stirring blades; one end of the second channel on the side wall of the guide tube is located higher than one end of the first channel on the side wall of the guide tube. One end of the first channel is arranged between the double-layer stirring blades in the guide tube, where the turbulent energy is the largest and the disturbance is the most intense, which is conducive to strengthening the mass transfer and heat transfer process.

[0011] As a preferred technical solution of the utility model, the jacket medium inlet and the jacket medium outlet are respectively connected to the inlet and outlet of the cooling medium circulation pump; the cooling medium circulation pump is used to circulate the cooling medium located in the crystallizer jacket, and the cooling medium can be selected from ethylene glycol or a mixture thereof with water, and the cooling medium temperature in the crystallizer jacket is -5°C to -10°C. Particularly preferably, the cooling medium is a mixture of ethylene glycol and water. In order to improve the cooling crystallization yield of sodium sulfate and facilitate the subsequent resource utilization of lithium sulfate, the cooling crystallization temperature of the solution in the crystallizer shell is controlled between -10°C and 5°C.

[0012] Preferably, the axial cross-section of the bottom of the crystallizer shell of the crystallizer shell is W-shaped, and a crystallizer discharge port is provided at the lowest point of the bottom of the crystallizer shell. The crystallizer bottom is set to be W-shaped, which is a design obtained through fluid mechanics simulation to reduce the flow dead zone, and is combined with a specially designed double-layer stirring paddle and guide tube to strengthen the slurry circulation.

[0013] Preferably, a high-pressure flushing device is externally connected to the crystallizer discharge port to allow water / solvent or steam with a temperature higher than 70° C. to clear the pipeline when the pipeline is blocked.

[0014] Preferably, the ratio of the diameter of the outer wall of the crystallizer jacket to the diameter of the outer wall of the crystallizer shell is 1.05-1.30, for example, it can be 1.10, 1.15, 1.20, 1.25, 1.30, but it is not limited to the listed values, and other values ​​not listed in this numerical range are equally applicable; the ratio of the height of the crystallizer jacket to the height of the crystallizer shell is 0.6-0.8, for example, it can be 0.60, 0.65, 0.70, 0.75, 0.80, but it is not limited to the listed values, and other values ​​not listed in this numerical range are equally applicable.

[0015] Preferably, the ratio of the height of the crystallizer shell to its diameter is 1.2-2.0; for example, it can be 1.20, 1.30, 1.40, 1.50, 1.60, 1.70, 1.80, but it is not limited to the listed values, and other values ​​not listed in the numerical range are also applicable; a higher height-to-diameter ratio is conducive to increasing the heat exchange area, enhancing the heat exchange efficiency, and effectively reducing the heat exchange temperature difference, thereby improving the original crystallizer scaling and pipeline blockage, short operation cycle and other problems. At the same time, it can also effectively inhibit the precipitation of lithium sulfate in the process and ensure the purity of the sodium sulfate product.

[0016] Preferably, the ratio of the height of the guide tube to the height of the crystallizer shell is 0.4-0.8, for example, it can be 0.4, 0.5, 0.6, 0.7, 0.8, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are equally applicable; the ratio of the diameter of the guide tube to the diameter of the crystallizer shell is 0.5-0.9, for example, it can be 0.5, 0.6, 0.7, 0.8, 0.9, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are equally applicable.

[0017] Preferably, the stirring directions of the two layers of stirring blades are consistent, and the stirring speed is 80 rpm, thereby enhancing the internal circulation effect of the solid-liquid mixed fluid.

[0018] Preferably, the ratio of the diameter of the double-layer stirring blade to the diameter of the guide tube is 0.6-0.95, for example, it can be 0.60, 0.65, 0.70, 0.80, 0.90, 0.95, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are equally applicable; the ratio of the vertical distance between the two layers of blades to the height of the guide tube is 0.6-0.9, for example, it can be 0.6, 0.7, 0.8, 0.9, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are equally applicable.

[0019] Preferably, the vertical distance ratio between the crystallizer feed port and the upper stirring blades and the lower stirring blades is in the range of 0.5-2.0, for example, 0.5, 1.0, 1.5, 2.0, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0020] Preferably, when the device is in stable operation, the ratio of the liquid level height of the solid-liquid two-phase material in the crystallizer shell to the height of the draft tube is 1.05-1.20, for example, it can be 1.05, 1.10, 1.15, 1.20, which is conducive to the circulation process in the slurry. The solid-liquid two-phase in the crystallizer flows from bottom to top in the draft tube, and flows from top to bottom along the draft tube and the crystallizer wall after turning over the draft tube. This design can effectively reduce the problem of pipeline blockage caused by the accumulation of sodium sulfate crystal products at the bottom of the crystallizer.

[0021] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0022] Compared with the prior art, the beneficial effects of the utility model are:

[0023] (1) The circulating crystallization device provided by the utility model realizes the internal circulation of the crystal slurry through the specific configuration of the crystallizer. Compared with the conventional OSLO crystallizer in this field, it effectively improves the fluid mechanics performance in the crystallizer, and avoids the deposition of solid particles at the bottom of the crystallizer, which causes the blockage of pipelines and equipment; at the same time, the heat and mass transfer efficiency is enhanced, and the prepared sodium sulfate crystal product has uniform particle size and good crystal morphology;

[0024] (2) The jacket internal circulation heat exchange method is adopted, combined with the crystallizer structure design with a large heat exchange area and optimized fluid mechanics performance, which effectively avoids crystal nucleation at the heat exchange interface, prevents blockage of the external circulation heat exchange pipeline and equipment wall problems;

[0025] (3) The crystallization residence time can be adjusted by controlling the feed and discharge speed of the liquid, effectively regulating the nucleation and growth of the crystal grains, and improving the problems of small product particle size, severe equipment scaling, and short operation cycle in the continuous crystallization process. In addition, the continuous cooling crystallization processing capacity of sodium sulfate can be increased by connecting multiple kettles in parallel, realizing large-scale production, improving the stable operation cycle of the continuous crystallization process, and ensuring product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of the continuous cooling crystallization device of the utility model.

[0027] In the figure:

[0028] 1: crystallizer shell; 2: crystallizer jacket; 3: jacket medium inlet; 4: jacket medium outlet; 5: crystallizer shell kettle head; 6: crystallizer shell cylinder; 7: crystallizer shell bottom; 8: guide tube; 9: stirring motor; 10: stirring blade; 11: turbidity meter and thermometer port; 12: crystallizer feed port; 13: crystallizer discharge port; 14: crystallizer discharge pipe flushing port; 15: first channel; 16: second channel. DETAILED DESCRIPTION

[0029] Those skilled in the art should understand that the present invention necessarily includes necessary pipelines, conventional valves and general pump equipment for realizing a complete process, but the above content does not constitute the main innovation of the present invention. Those skilled in the art can add layouts on their own based on the process flow and equipment structure selection, and the present invention does not make special requirements or specific limitations on this.

[0030] Those skilled in the art can realize the present invention by appropriately changing some aspects such as the structure size and structure form of the equipment by referring to the contents of this article. The equipment of the utility model has been described through the preferred embodiment examples. It is obvious that relevant technical personnel can modify or appropriately change and combine the methods and products described in this article without departing from the content, spirit and scope of this patent to realize the equipment of the utility model. It is particularly important to point out that all similar substitutions and modifications are obvious to those skilled in the art, and they are all deemed to be included in the spirit, scope and content of the present utility model.

[0031] In order to make the purpose, technical scheme, beneficial effects and significant progress of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model is clearly and completely described below in combination with the drawings provided in the examples of the utility model. Obviously, all the described embodiments are only partial embodiments of the utility model, rather than all embodiments; based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the utility model.

[0032] The working process of the device will be further described below in conjunction with the accompanying drawings.

[0033] like Figure 1As shown, a continuous cooling crystallization device for recovering and extracting sodium sulfate from waste battery electrolyte, the cooling crystallization device comprises an openable and closable crystallizer shell 1 and a crystallizer jacket 2, the crystallizer jacket 2 is fixedly sleeved on the outer wall of the crystallizer shell 1. The thickness of the crystallizer jacket is 0.2m, and the crystallizer jacket is a hollow structure, wherein the hollow part is used to place a cooling medium, and the cooling medium can be a mixture of ethylene glycol and water, and the temperature is set at -8°C. The crystallizer jacket 2 is externally connected to a cooling medium circulation pump for circulating the cooling medium in the jacket 2. Of course, according to actual needs, the cooling medium can also be uniformly distributed through the public works of the plant area, and the utility model does not limit the source of the cooling medium.

[0034] The outer wall of the crystallizer jacket 2 is provided with a jacket medium inlet 3 and a jacket medium outlet 4. The cooling medium in the crystallizer jacket 2 flows into the jacket from the jacket medium inlet 3 and flows out from the jacket medium outlet 4, and the jacket medium outlet 4 is located at a higher position than the jacket medium inlet 3.

[0035] The crystallizer shell 1 includes a crystallizer shell kettle head 5, a crystallizer shell cylinder 6 and a crystallizer bottom 7 from top to bottom. The crystallizer shell kettle head 5 and the crystallizer shell cylinder 6 are detachably bolted. The crystallizer shell cylinder 6 and the crystallizer shell bottom 7 are integrally formed. The axial section of the crystallizer shell bottom 7 is W-shaped, and a crystallizer discharge port 13 is provided at the lowest point of the crystallizer shell bottom 7. A crystallizer discharge pipe flushing port 14 is also provided at the crystallizer discharge port 13. The crystallizer discharge pipe flushing port 14 is externally connected to a high-pressure flushing device. If the pipeline is blocked, high-temperature hot water or steam can be introduced to clear the pipeline.

[0036] A coaxial sleeve-shaped draft tube 8 is also provided inside the crystallizer shell 1. The diameter of the crystallizer shell kettle head 5 is 1.8m, the height is 0.5m, the diameter of the crystallizer shell cylinder 6 is 1.8m, the height is 2.5m; the diameter of the draft tube 8 is 1.4m, the height is 2.0m, and the minimum distance between the lower edge of the draft tube and the bottom of the crystallizer is 0.4m.

[0037] A stirring motor 9 is arranged on the top of the kettle head 5 of the crystallizer shell, and a rod is connected to the lower part of the stirring motor 9, and the rod extends into the guide tube 8, and a double-layer stirring blade 10 is arranged on the rod, and its diameter is smaller than the diameter of the guide tube; and the lower stirring blade is flush with the lower edge of the guide tube, and the stirring direction of the two layers of stirring blades 10 is consistent, and the stirring speed is 80rpm, the purpose of which is to strengthen the circulation flow in the crystallizer. The stirring blade 10 is a propulsion stirring blade, and its diameter is 1.3m, and the vertical distance between the two layers of stirring blades is 1.4m.

[0038] One end of a first channel 15 is located on the side wall of the guide tube (and between the double-layer stirring blades 10, with a vertical distance of 0.5m from the lower stirring blade), and passes through the crystallizer shell cylinder 6 and the crystallizer jacket 2 in sequence and then extends out of the outer wall of the crystallizer jacket 2. The other end of the first channel 15 is a free end as a crystallizer feed port 12, and the crystallizer feed port 12 is used to directly add materials into the guide tube 8. One end of the second channel 16 extends into the crystallizer shell cylinder 6 (and the end is 1.0m vertically away from the lower edge of the guide tube 8, and 0.1-0.5m laterally away from the outer wall of the guide tube), and passes through the crystallizer jacket 2 and then extends out of the outer wall of the crystallizer jacket 2. The other end of the second channel 16 is a free end as a turbidity meter and thermometer port 11, which is used to insert a turbidity meter and a thermometer to detect the crystallization process. Moreover, one end of the second channel 16 located on the side wall of the guide tube is arranged opposite to one end of the first channel 15 located on the side wall of the guide tube and is located higher than one end of the first channel located on the side wall of the guide tube.

[0039] Exemplarily, the continuous cooling crystallization device provided by the utility model is used for crystallization and separation of sodium sulfate in battery electrolyte, and the process specifically includes the following steps:

[0040] (1) Under normal temperature conditions, a mixed solution containing sodium sulfate and lithium sulfate is added from the crystallizer feed port 12 to the guide tube 8 of the continuous cooling crystallization device. After the liquid level exceeds the upper edge of the guide tube (preferably the liquid level is 0.2 m higher than the upper edge of the guide tube), the feed is closed and the stirring motor 9 is turned on. The stirring speed is preferably 20-100 rpm;

[0041] (2) A mixture of ethylene glycol and water is used as the cooling medium in the crystallizer jacket 2, and the cooling medium circulation pump is turned on. The cooling medium temperature is set to -5°C to -10°C according to the required heat exchange area and heat exchange amount, and cooling crystallization is turned on until sodium sulfate crystals are precipitated; under the action of the double-layer stirring blades 10, the guide tube 9 and the bottom 7 of the W-type crystallizer shell, the slurry flows from bottom to top in the guide tube, and after turning over the guide tube, it flows from top to bottom along the guide tube and the inner wall of the crystallizer shell cylinder 6 to ensure the suspension effect of solid particles in the slurry; this design can effectively reduce the problem of pipeline blockage caused by the accumulation of sodium sulfate crystal products at the bottom of the crystallizer;

[0042] (3) After the crystallization system is running stably, the valves set at the crystallizer feed port 12 and the crystallizer discharge port 13 are opened, and the inlet and outlet flow rates are adjusted according to the residence time required by the process. The discharge product enters the solid-liquid separation device, and the separated sodium sulfate crystals are dried to obtain a crystal product. The crystallization mother liquor enters the subsequent lithium sulfate separation unit operation.

[0043] The applicant declares that the above is only a specific implementation method of the present utility model, but the protection scope of the present utility model is not limited thereto. The technicians in the relevant technical field should understand that any changes or substitutions that can be easily thought of by the technicians in the relevant technical field within the technical scope disclosed in the present utility model fall within the protection scope and disclosure scope of the present utility model.

Claims

1. A continuous cooling crystallization device for recovering and extracting sodium sulfate from waste battery electrolyte, characterized in that: The invention comprises a crystallizer shell (1) and a crystallizer jacket (2); the crystallizer jacket (2) is fixedly sleeved on the outer wall of the crystallizer shell (1); a circulating cooling medium is introduced into the crystallizer jacket (2), and a jacket medium inlet (3) and a jacket medium outlet (4) are provided on the outer wall of the crystallizer jacket (2), and the jacket medium outlet (4) is located at a position higher than the jacket medium inlet (3); A coaxial sleeve-shaped draft tube (8) is arranged inside the crystallizer shell (1), a stirring motor (9) is arranged on the top, and two layers of stirring blades (10) are arranged below the stirring motor (9). Both layers of stirring blades (10) are located inside the draft tube, and the lower layer of stirring blades is flush with the lower edge of the draft tube (8); One end of a first channel (15) is located on the side wall of the guide tube, and passes through the crystallizer shell cylinder (6) and the crystallizer jacket (2) in sequence and then extends out of the outer wall of the crystallizer jacket (2). The other end of the first channel (15) serves as a crystallizer feed port (12) for directly adding materials into the guide tube (8); One end of a second channel (16) extends into the crystallizer shell cylinder (6) and is 0.1-0.5 m away from the outer wall of the guide tube, passes through the crystallizer jacket (2) and then extends out of the outer wall of the crystallizer jacket (2); the other end of the second channel (16) serves as a turbidity meter and thermometer port (11) for inserting the turbidity meter and thermometer to detect the crystallization process; Furthermore, one end of the first channel (15) located on the side wall of the guide tube is located between two layers of stirring blades (10); and one end of the second channel (16) located on the side wall of the guide tube is located higher than one end of the first channel (15) located on the side wall of the guide tube.

2. The continuous cooling crystallization device according to claim 1, characterized in that: The cooling medium is ethylene glycol or a mixture of ethylene glycol and water. The temperature of the cooling medium in the crystallizer jacket (2) is between -5°C and -10°C. The temperature of the solution in the crystallizer shell (1) is controlled between -10°C and 5°C.

3. The continuous cooling crystallization device according to claim 1, characterized in that: The stirring directions of the two layers of stirring blades (10) are consistent, the ratio of the diameter of the two layers of stirring blades (10) to the diameter of the guide tube is 0.6-0.95, and the ratio of the distance between the blades to the height of the guide tube is 0.6-0.

9.

4. The continuous cooling crystallization device according to claim 1, characterized in that: The axial cross-section of the bottom (7) of the crystallizer shell (1) is W-shaped, and a crystallizer discharge port (13) is provided at the lowest point of the bottom (7) of the crystallizer shell.

5. The continuous cooling crystallization device according to claim 4, characterized in that: The crystallizer discharge port (13) is externally connected to a high-pressure flushing device for introducing water, solvent or steam with a temperature higher than 70° C. to clear the pipeline when the pipeline is blocked.

6. The continuous cooling crystallization device according to claim 1, characterized in that: The ratio of the diameter of the outer wall of the crystallizer jacket (2) to the diameter of the outer wall of the crystallizer shell (1) is 1.05-1.30; the ratio of the height of the crystallizer jacket (2) to the height of the crystallizer shell (1) is 0.6-0.

8.

7. The continuous cooling crystallization device according to claim 1, characterized in that: The ratio of the height of the crystallizer shell (1) to its diameter is 1.2-2.

0.

8. The continuous cooling crystallization device according to claim 1, characterized in that: The ratio of the height of the guide tube (8) to the height of the crystallizer shell (1) is 0.4-0.8, and the ratio of the diameter of the guide tube (8) to the diameter of the crystallizer shell (1) is 0.5-0.

9.

9. The continuous cooling crystallization device according to claim 1, characterized in that: The vertical distance ratio between the crystallizer feed port (12) and the upper stirring blades and the lower stirring blades is 0.5-2.

0.

10. The continuous cooling crystallization device according to claim 1, characterized in that: When the device is in stable operation, the ratio of the liquid level of the solid-liquid two-phase material in the crystallizer shell (1) to the height of the draft tube is 1.05-1.20.

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