Lithium recovery device for wet process section of lithium carbonate production

Abstract

The utility model discloses a lithium carbonate production wet process section lithium recovery device which is characterized in that a lithium precipitation mother liquor pipe is connected with a circulating pipe of an MVR crystallizer, a salt leg outlet of the MVR crystallizer is connected with an MVR thickening tank, a bottom outlet of the MVR thickening tank is connected with an inlet of an MVR centrifugal machine, and a solid phase outlet of the MVR centrifugal machine is connected with an inlet of a salt leaching tank; a liquid phase outlet of the MVR centrifugal machine is connected with an MVR mother liquor tank, an outlet of the MVR mother liquor tank is connected with a reflux inlet of the MVR crystallizer and a feed inlet of the freezing crystallizer, a bottom outlet of the freezing crystallizer is connected with an inlet of the freezing thickening tank, and a bottom outlet of the freezing thickening tank is connected with an inlet of the freezing centrifugal machine; a liquid phase outlet of the freezing centrifugal machine is connected with a freezing mother liquor tank; a bottom outlet of the freezing mother liquor tank is connected with a circulating pipe of the freezing crystallizer and a lithium sulfate discharging pipe. The device can improve the lithium recycling rate, the sodium sulfate quality and the product stability, and reduce the energy consumption and the labor cost.

Description

Technical Field

[0001] The utility model relates to a lithium carbonate production device, in particular to a lithium recovery device for the wet section of lithium carbonate production, belonging to the technical field of comprehensive utilization of resources. Background Art

[0002] Based on the rapid development of the new energy electric vehicle and lithium-ion intelligent device industries in recent years, the global demand for lithium resources has shown an explosive growth. As an essential raw material for lithium-ion batteries, the demand for lithium carbonate has also been continuously rising. A large amount of mother liquor for lithium precipitation is generated in the lithium carbonate production line, and the process of recycling the mother liquor for lithium precipitation is also an important part of the lithium carbonate production line. Usually, MVR evaporation crystallization and freeze crystallization are used to increase the lithium concentration and remove potassium and sodium salts. At present, this process faces problems such as resource waste caused by part of lithium sulfate carried in the by-product salt and low selling price due to low purity of the by-product salt.

[0003] In the face of this problem, most of the recycling methods in the industry are to dissolve the sodium sulfate crystals containing lithium sulfate produced in the MVR evaporation crystallization process with pure water, redissolve the lithium sulfate in the solution, and then centrifuge the sodium sulfate crystals again. After the lithium sulfate concentration is high, the salt washing solution is returned to the MVR system for re-evaporation. This intermittent operation requires regular detection of the lithium concentration in the solution to control the external discharge and make-up liquid, and the cost of pure water is relatively high. It not only severely restricts the processing capacity, but also may lead to serious problems such as high energy consumption and high labor costs, seriously restricting the development of enterprises. Therefore, there is an urgent need for a continuously operating device with low cost and high lithium recovery rate to achieve the development goals of cost reduction, efficiency increase of enterprises and improvement of competitiveness in the industry.

[0004] The Chinese authorized patent with the publication number of CN112142080B discloses a method for preparing battery-grade lithium carbonate by freezing and recycling the concentrated mother liquor for lithium precipitation, including the following steps: lepidolite is roasted and leached to obtain a leaching solution, the leaching solution is purified, concentrated and evaporated, precipitated with lithium, and filtered to obtain lithium carbonate and mother liquor for lithium precipitation; the mother liquor for lithium precipitation is concentrated and evaporated to obtain a concentrated mother liquor for lithium precipitation; the concentrated mother liquor for lithium precipitation is added to the leaching solution to obtain a mixed solution, the mixed solution is purified, concentrated, evaporated, frozen to remove potassium and sodium salts, filtered and then introduced into an ion exchange resin to remove calcium and magnesium, and after sedimentation, battery-grade lithium carbonate and mother liquor for lithium precipitation are obtained, and the mother liquor for lithium precipitation is treated and recycled in the process. The technical solution has the following defects: 1. The purity of the sodium sulfate crystals precipitated by the MVR evaporation crystallization system is not high - the mother liquor for lithium precipitation is a multi-component solution of sodium sulfate, potassium sulfate and lithium sulfate, and potassium sulfate and a small amount of lithium sulfate will precipitate together with sodium sulfate during the evaporation crystallization process; 2. A small amount of lithium sulfate is carried out in the sodium sulfate solid, resulting in waste of lithium resources; 3. It does not explain how to handle the mirabilite precipitated by freezing. Content of the Utility Model

[0005] The purpose of this section is to outline some aspects of the embodiments of the present utility model and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section, as well as in the abstract and the title of the specification of this application, but such simplifications or omissions shall not be used to limit the scope of the present utility model.

[0006] In view of the above and / or problems existing in the prior art, the present utility model is proposed.

[0007] The purpose of the present utility model is to overcome the problems existing in the prior art and provide a lithium recovery device for the wet process section of lithium carbonate production, which can improve the lithium recovery utilization rate, the quality of sodium sulfate and the product stability, and reduce the energy consumption and labor costs.

[0008] To solve the above technical problems, a lithium recovery device for the wet process section of lithium carbonate production according to the present utility model includes a mother liquor pipe for lithium precipitation. The first outlet of the mother liquor pipe for lithium precipitation and the circulation outlet of the MVR crystallizer are jointly connected to the inlet of the tube side of the evaporator. The outlet of the tube side of the evaporator is connected to the circulation inlet of the MVR crystallizer through an MVR forced circulation pump. The salt leg outlet of the MVR crystallizer is connected to the inlet of the MVR thickener through an MVR crystal slurry pump. The bottom outlet of the MVR thickener is connected to the inlet of the MVR centrifuge. The solid phase outlet of the MVR centrifuge is connected to the inlet of the salt washing tank.

[0009] The liquid phase outlet of the MVR centrifuge is connected to the MVR mother liquor tank. The outlet of the MVR mother liquor tank is connected to the reflux port of the MVR crystallizer and the feed port of the freeze crystallizer through an MVR mother liquor pump. The bottom outlet of the freeze crystallizer is connected to the inlet of the freeze thickener through a freeze crystal slurry pump. The bottom outlet of the freeze thickener is connected to the inlet of the freeze centrifuge. The liquid phase outlet of the freeze centrifuge is connected to the freeze mother liquor tank. The bottom outlet of the freeze mother liquor tank is connected to the inlet of the freeze mother liquor pump. The outlet of the freeze mother liquor pump is connected to the circulation pipe of the freeze crystallizer and the external discharge pipe of lithium sulfate.

[0010] The solid phase outlet of the freeze centrifuge and the second outlet of the mother liquor pipe for lithium precipitation are respectively connected to a hot melt tank. The bottom outlet of the hot melt tank is connected to the inlet of the salt washing tank through a hot melt discharge pump. The bottom outlet of the salt washing tank is connected to the inlet of the salt washing thickener through a salt washing pump. The bottom outlet of the salt washing thickener is connected to the inlet of the salt washing centrifuge. The solid phase outlet of the salt washing centrifuge is connected to a high-purity sodium sulfate discharge pipe.

[0011] As an improvement of the present utility model, the liquid phase outlet of the salt washing centrifuge is connected to the inlet of the salt washing mother liquor tank. The bottom outlet of the salt washing mother liquor tank is connected to the reflux port of the MVR crystallizer through a salt washing mother liquor pump.

[0012] As a further improvement of the present utility model, the secondary steam outlet at the top of the MVR crystallizer is connected to the inlet of the MVR compressor, the outlet of the MVR compressor is connected to the inlet of the shell side of the evaporator, and the outlet of the shell side of the evaporator is connected to the condensate tank.

[0013] Compared with the prior art, the present utility model has achieved the following beneficial effects: 1. By adding the lithium precipitation mother liquor into the hot melt tank, heat consumption is reduced, the influence of adding water into the MVR crystallization system in the hot melt system is eliminated, the operation efficiency and stability of the whole production system are improved, and the operation cost is reduced.

[0014] 2. The recovery rate of lithium is greatly improved, and the production cost is reduced; at the same time, the lithium sulfate in the solid sodium sulfate salt is reduced, the purity of sodium sulfate is improved, and the selling price is increased.

[0015] 3. The sodium sulfate saturated solution with a low lithium content is used to replace pure water for salt washing, reducing the production cost; at the same time, the problem of unstable salt output during the water replenishment of the pure water salt washing system is solved, and the operation efficiency and stability of the salt washing system are improved.

[0016] 4. The sodium sulfate saturated solution with a low lithium content generated by the hot melt system is used for salt washing and lithium resource recovery, maximizing the utilization of the existing resources in the system, reducing resource waste, and reducing the operation cost and installation cost.

[0017] 5. The lithium content in the salt washing mother liquor is higher than that in the feed of the MVR crystallization process. Even if the salt washing mother liquor continuously enters the MVR system, it will not affect the stable operation of the system and the material concentration, and stable and continuous feeding and discharging can be achieved, improving the operation efficiency and stability of the whole system; the problem of frequently detecting the lithium concentration and regularly discharging and replenishing water when using pure water for salt washing is solved, reducing the operation personnel cost and the later operation and maintenance cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present utility model. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts. The drawings are only for reference and illustration, and are not used to limit the present utility model. Among them:

[0019] Figure 1 is the flow chart of the lithium recovery device in the wet process section of lithium carbonate production of the present utility model;

[0020] In the figure: 1. Freezing crystallizer; 2. Freezing heat exchanger; 3. Freezing thickening tank; 4. Freezing centrifuge; 5. Freezing mother liquor tank; 6. Melting tank; 7. Salt washing tank; 8. Salt washing thickening tank; 9. Salt washing centrifuge; 10. Belt conveyor; 11. Salt washing mother liquor tank; 12. MVR crystallizer; 13. MVR compressor; 14. Evaporator; 15. Condensate water tank; 16. MVR thickening tank; 17. MVR centrifuge; 18. MVR mother liquor tank;

[0021] G1. Lithium precipitation mother liquor pipe; G2. MVR crystallization feed pipe; G3. Lithium precipitation mother liquor into melting pipe; G4. MVR crystallization circulation pipe; G5. MVR crystal slurry discharge pipe; G6. MVR crystallization mother liquor pipe; G7. MVR crystallization mother liquor reflux pipe; G8. MVR crystallization mother liquor intermediate pipe; G9. MVR salt discharge pipe; G10. Freezing system circulation pipe; G11. Freezing crystal slurry pipe; G12. Freezing salt discharge pipe; G13. Melting discharge pipe; G14. Salt washing crystal slurry pipe; G15. Salt washing mother liquor reflux pipe; G16. High-purity sodium sulfate discharge pipe; G17. Lithium sulfate external discharge pipe;

[0022] B1. Refrigerant circulation pump; B2. Freezing circulation pump; B3. Freezing crystal slurry pump; B4. Freezing mother liquor pump; B5. Melting discharge pump; B6. Salt washing pump; B7. Salt washing mother liquor pump; B8. MVR forced circulation pump; B9. MVR crystal slurry pump; B10. MVR mother liquor pump; B11. Condensate water pump. Detailed implementation manners

[0023] In the following description of the present utility model, the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present utility model and simplifying the description, rather than indicating that the device must have a specific orientation.

[0024] In order to make the technical means, creative features, achieved purposes and effects realized by the present utility model easy to understand, the present utility model will be further described below with reference to specific drawings. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all of the embodiments.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present utility model belongs. The terms used in the description of the present utility model herein are only for the purpose of describing specific embodiments, and are not intended to limit the present utility model.

[0026] Such as Figure 1As shown in the figure, the lithium recovery device in the wet section of lithium carbonate production of the present utility model includes a freezing crystallizer 1, a freezing heat exchanger 2, a freezing thickening tank 3, a freezing centrifuge 4, a freezing mother liquor tank 5, a hot melting tank 6, a salt washing tank 7, a salt washing thickening tank 8, a salt washing centrifuge 9, a belt conveyor 10, a salt washing mother liquor tank 11, an MVR crystallizer 12, an MVR compressor 13, an evaporator 14, a condensate water tank 15, an MVR thickening tank 16, an MVR centrifuge 17 and an MVR mother liquor tank 18.

[0027] The first outlet of the lithium precipitation mother liquor pipe G1 and the circulation outlet of the MVR crystallizer 12 are jointly connected to the tube side inlet of the evaporator 14 through the MVR crystallization feed pipe G2. The tube side outlet of the evaporator 14 is connected to the inlet of the MVR forced circulation pump B8. The outlet of the MVR forced circulation pump B8 is connected to the circulation inlet of the MVR crystallizer 12 through the MVR crystallization circulation pipe G4. The salt leg outlet of the MVR crystallizer 12 is connected to the inlet of the MVR slurry pump B9. The outlet of the MVR slurry pump B9 is connected to the inlet of the MVR thickening tank 16 through the MVR slurry discharge pipe G5. The bottom outlet of the MVR thickening tank 16 is connected to the inlet of the MVR centrifuge 17. The solid phase outlet of the MVR centrifuge 17 is connected to the inlet of the salt washing tank 7.

[0028] The overflow port of the MVR thickening tank 16 and the liquid phase outlet of the MVR centrifuge 17 are connected to the MVR mother liquor tank 18. The outlet of the MVR mother liquor tank 18 is connected to the inlet of the MVR mother liquor pump B10. The outlet of the MVR mother liquor pump B10 is connected to the MVR crystallization mother liquor pipe G6. The outlet of the MVR crystallization mother liquor pipe G6 is respectively connected to the MVR crystallization mother liquor return pipe G7 and the MVR crystallization mother liquor intermediate pipe G8. The outlet of the MVR crystallization mother liquor return pipe G7 is connected to the return port of the MVR crystallizer 12 and the feed port of the freezing crystallizer 1. The circulating liquid outlet of the freezing crystallizer 1 is connected to the inlet of the freezing circulation pump B2 through the freezing system circulation pipe G10. The outlet of the freezing circulation pump B2 is connected to the tube side inlet of the freezing heat exchanger 2. The outlet of the MVR crystallization mother liquor intermediate pipe G8 and the tube side outlet of the freezing heat exchanger 2 are jointly connected to the top feed port of the freezing crystallizer 1.

[0029] The bottom outlet of the freezing crystallizer 1 is connected to the inlet of the freezing slurry pump B3. The outlet of the freezing slurry pump B3 is connected to the inlet of the freezing thickening tank 3 through the freezing slurry pipe G11. The bottom outlet of the freezing thickening tank 3 is connected to the inlet of the freezing centrifuge 4. The liquid phase outlet of the freezing centrifuge 4 is connected to the freezing mother liquor tank 5. The bottom outlet of the freezing mother liquor tank 5 is connected to the inlet of the freezing mother liquor pump B4. The outlet of the freezing mother liquor pump B4 is connected to the circulation pipe of the freezing crystallizer 1 and the lithium sulfate external discharge pipe G17.

[0030] The solid-phase outlet of the refrigerated centrifuge 4 is connected to the hot-melt tank 6 through the refrigerated salt-out pipe G12. The second outlet of the lithium precipitation mother liquor pipe G1 is also connected to the hot-melt tank 6 through the lithium precipitation mother liquor inlet hot-melt pipe G3. The bottom outlet of the hot-melt tank 6 is connected to the inlet of the hot-melt discharge pump B5. The outlet of the hot-melt discharge pump B5 is connected to the inlet of the salt-washing tank 7 through the hot-melt discharge pipe G13. The bottom outlet of the salt-washing tank 7 is connected to the inlet of the salt-washing pump B6. The outlet of the salt-washing pump B6 is connected to the inlet of the salt-washing thickening tank 8 through the salt-washing crystal slurry pipe G14. The bottom outlet of the salt-washing thickening tank 8 is connected to the inlet of the salt-washing centrifuge 9. The solid-phase outlet of the salt-washing centrifuge 9 is connected to the belt conveyor 10 through the high-purity sodium sulfate discharge pipe G16.

[0031] The overflow port of the salt-washing thickening tank 8 and the liquid-phase outlet of the salt-washing centrifuge 9 are both connected to the inlet of the salt-washing mother liquor tank 11. The bottom outlet of the salt-washing mother liquor tank 11 is connected to the inlet of the salt-washing mother liquor pump B7. The outlet of the salt-washing mother liquor pump B7 is connected to the return port of the MVR crystallizer 12 through the salt-washing mother liquor return pipe G15.

[0032] The top secondary steam outlet of the MVR crystallizer 12 is connected to the inlet of the MVR compressor 13. The outlet of the MVR compressor 13 is connected to the shell-side inlet of the evaporator 14. The shell-side outlet of the evaporator 14 is connected to the condensate tank 15.

[0033] The lithium precipitation mother liquor from the lithium precipitation mother liquor pipe G1 enters the MVR crystallization feed pipe G2, mixes with the circulating feed liquid discharged from the MVR crystallizer 12, and then jointly enters the tube side of the evaporator 14 for heating. The secondary steam discharged from the top of the MVR crystallizer 12 enters the MVR compressor 13 for compression. After the temperature is increased, it enters the shell side of the evaporator 14 as a heat medium. After heat exchange, it becomes condensate and is collected in the condensate tank 15, and then is sent out for reuse by the condensate pump B11.

[0034] The feed liquid heated by the evaporator 14 is sent out by the MVR forced circulation pump B8 and returns to the MVR crystallizer 12 through the MVR crystallization circulation pipe G4 for circulation. After evaporation, concentration and crystallization in the MVR crystallizer 12, it is discharged from the salt leg, pumped into the MVR thickening tank 16 through the MVR crystal slurry pump B9 and the MVR crystal slurry discharge pipe G5 for sedimentation. After sedimentation, it enters the MVR centrifuge 17 for solid-liquid separation. The solid-phase outlet of the MVR centrifuge 17 discharges the sodium sulfate solid salt wrapped with lithium sulfate and enters the salt-washing tank 7 for salt washing.

[0035] The centrifugal mother liquor discharged from the liquid phase of the MVR centrifuge 17 enters the MVR mother liquor tank 18. The centrifugal mother liquor is sent out by the MVR mother liquor pump B10 and the MVR crystallization mother liquor pipe G6. A part of the mother liquor containing fine crystals is refluxed to the MVR crystallizer 12 for secondary growth through the MVR crystallization mother liquor return pipe G7, and the other part is discharged through the MVR crystallization mother liquor intermediate pipe G8. Then the saturated sodium sulfate solution enters the refrigerated crystallization system to remove impurities such as potassium and sodium.

[0036] The MVR mother liquor enters the freezing crystallizer 1 of the freezing crystallization system and cools down to 5°C, where a large amount of mirabilite precipitates. The overflow of the freezing crystallizer 1 enters the inlet of the freezing circulation pump B2 through the freezing system circulation pipe G10. The freezing circulation pump B2 sends it into the tube side of the freezing heat exchanger 2. After cooling, it is mixed with the MVR mother liquor from the MVR crystallization mother liquor intermediate pipe G8 and then returns to the freezing crystallizer 1 for circulation. The shell side of the freezing heat exchanger 2 maintains the refrigerant circulation by the refrigerant circulation pump B1.

[0037] The mirabilite discharged from the bottom of the freezing crystallizer 1 is sent into the freezing thickening tank 3 for sedimentation through the freezing slurry pump B3 and the freezing slurry pipe G11. After sedimentation, it enters the freezing centrifuge 4 for solid-liquid separation. The centrifugal mother liquor discharged from the liquid phase of the freezing centrifuge 4 enters the freezing mother liquor tank 5 and is sent out through the freezing mother liquor pump B4. Part of the sodium sulfate fine crystals flow back to the freezing crystallizer 1 to continue growing the crystal particles, and the other part is discharged through the lithium sulfate external discharge pipe G17 to produce lithium sulfate finished products.

[0038] The solid mirabilite discharged from the solid phase of the freezing centrifuge 4 enters the hot melting tank 6 through the freezing salt discharge pipe G12. Part of the lithium precipitation mother liquor from the lithium precipitation mother liquor pipe G1 also enters the hot melting tank 6 through the lithium precipitation mother liquor into hot melting pipe G3. The hot melting tank 6 is heated to dissolve the solid mirabilite into a saturated sodium sulfate solution with a low lithium content rate, and it is sent into the salt washing tank 7 through the hot melting discharge pump B5 and the hot melting discharge pipe G13.

[0039] After the saturated sodium sulfate solution with a low lithium content rate enters the salt washing tank 7, it is mixed and stirred evenly with the sodium sulfate solid containing lithium sulfate separated by the MVR centrifuge 17 to form a supersaturated crystal slurry. The lithium sulfate contained in the sodium sulfate solid dissolves into the saturated sodium sulfate solution with a low lithium content rate, and then it is pumped into the salt washing thickening tank 8 through the salt washing pump B6 and the salt washing crystal slurry pipe G14 for sedimentation. After sedimentation, it enters the salt washing centrifuge 9 for solid-liquid separation. The solid phase discharged is high-quality sodium sulfate, which is sent out through the high-purity sodium sulfate discharge pipe G16 and the belt conveyor 10 for sale as by-product Glauber's salt.

[0040] The mother liquor discharged from the liquid phase of the salt washing centrifuge 9 and the mother liquor discharged from the overflow of the salt washing thickening tank 8 enter the salt washing mother liquor tank 11 and are sent out through the salt washing mother liquor pump B7, and then return to the MVR crystallizer 12 through the salt washing mother liquor return pipe G15 for re-evaporation and utilization. Here, the lithium content and sodium content in the salt washing mother liquor are both higher than those in the lithium precipitation mother liquor, so this mother liquor has no impact on the stable operation of the MVR evaporation crystallization system, achieving the operation effect of low cost, high lithium recovery rate, and continuous stability.

[0041] The above are only the preferred and feasible embodiments of the present utility model, which illustrate and describe the basic principles, main features and advantages of the present utility model. It is not intended to limit the patent protection scope of the present utility model thereby. Those skilled in the art should understand that the present utility model is not restricted by the above embodiments. Except for the above embodiments, without departing from the spirit and scope of the present utility model, the present utility model may have other implementation manners. There will also be various changes and improvements to the present utility model. All technical solutions formed by equivalent substitution or equivalent transformation fall within the protection scope required by the present utility model. The protection scope required by the present utility model is defined by the appended claims and their equivalents. The technical features not described in the present utility model can be realized by or adopt the prior art, and will not be elaborated herein.

Claims

1. A lithium recovery device for the wet process section of lithium carbonate production, including a mother liquor pipe for lithium precipitation, characterized in that: The outlet one of the lithium precipitation mother liquor pipe and the circulation outlet of the MVR crystallizer are jointly connected to the tube side inlet of the evaporator. The tube side outlet of the evaporator is connected to the circulation inlet of the MVR crystallizer through the MVR forced circulation pump. The salt leg outlet of the MVR crystallizer is connected to the inlet of the MVR thickener through the MVR slurry pump. The bottom outlet of the MVR thickener is connected to the inlet of the MVR centrifuge. The solid phase outlet of the MVR centrifuge is connected to the inlet of the salt washing tank. The liquid phase outlet of the MVR centrifuge is connected to the MVR mother liquor tank. The outlet of the MVR mother liquor tank is connected to the reflux port of the MVR crystallizer and the feed port of the freeze crystallizer through the MVR mother liquor pump. The bottom outlet of the freeze crystallizer is connected to the inlet of the freeze thickener through the freeze slurry pump. The bottom outlet of the freeze thickener is connected to the inlet of the freeze centrifuge. The liquid phase outlet of the freeze centrifuge is connected to the freeze mother liquor tank. The bottom outlet of the freeze mother liquor tank is connected to the inlet of the freeze mother liquor pump. The outlet of the freeze mother liquor pump is connected to the circulation pipe of the freeze crystallizer and the lithium sulfate discharge pipe. The solid phase outlet of the freeze centrifuge and the outlet two of the lithium precipitation mother liquor pipe are respectively connected to the hot melt tank. The bottom outlet of the hot melt tank is connected to the inlet of the salt washing tank through the hot melt discharge pump. The bottom outlet of the salt washing tank is connected to the inlet of the salt washing thickener through the salt washing pump. The bottom outlet of the salt washing thickener is connected to the inlet of the salt washing centrifuge. The solid phase outlet of the salt washing centrifuge is connected to the high purity sodium sulfate discharge pipe.

2. The lithium recovery device in the wet process section for lithium carbonate production according to claim 1, wherein: The liquid phase outlet of the salt washing centrifuge is connected to the inlet of the salt washing mother liquor tank. The bottom outlet of the salt washing mother liquor tank is connected to the reflux port of the MVR crystallizer through the salt washing mother liquor pump.

3. The lithium recovery device in the wet process section for lithium carbonate production according to claim 2, wherein: The top secondary steam outlet of the MVR crystallizer is connected to the inlet of the MVR compressor. The outlet of the MVR compressor is connected to the shell side inlet of the evaporator. The shell side outlet of the evaporator is connected to the condensate tank.

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