System for producing battery-grade lithium carbonate by hydrogenolysis method

Abstract

The utility model discloses a system for producing battery-grade lithium carbonate by using a hydrogenation decomposition method, which comprises a raw material buffer pool for accommodating lithium carbonate slurry, and an outlet of the raw material buffer pool is connected with a circulating pipe of a carbonization bubble tower through a raw material feeding pump; the circulating pipe of the carbonization bubbling tower is further connected with a lithium bicarbonate three-stage filtering and impurity removing unit through a carbonization discharging pump, a filtrate outlet of the lithium bicarbonate three-stage filtering and impurity removing unit is connected with a circulating pipe of a pyrolysis crystallizer, and a crystal mush outlet of the pyrolysis crystallizer is connected with an inlet of a pyrolysis thickening tank through a lithium carbonate crystal mush pump; a solid-phase outlet of the pyrolysis thickening tank is connected with an inlet of the centrifugal machine, a solid-phase outlet of the centrifugal machine is connected with an inlet of the product fluidized bed, and a discharge port of the product fluidized bed is connected with a battery-grade lithium carbonate conveying pipe. The system can realize efficient purification of wet industrial grade lithium carbonate, so that the produced lithium carbonate reaches battery grade purity, the yield and the production efficiency of the lithium carbonate are improved, and the material consumption and the energy consumption are reduced.

Description

Technical Field

[0001] The utility model relates to a lithium carbonate production system, in particular to a system for producing battery-grade lithium carbonate by hydrogenation decomposition method, belonging to the technical field of resource recycling. Background Art

[0002] Lithium carbonate is a commonly used industrial inorganic compound, which can be used in ceramics, medicines, chemical catalysts, etc. At the same time, it is also used as the cathode material of lithium batteries, with advantages such as high energy density, long service life and good stability, and has very large application prospects and market demands. The hydrogenation decomposition method is the most commonly used process for industrial purification of lithium carbonate at present. How to more efficiently recycle the carbon dioxide generated by the hydrogenation decomposition method of lithium carbonate has become a hot topic in market research.

[0003] Battery-grade lithium carbonate requires a lithium carbonate content of more than 99.5% and has relatively high requirements for the content of metal impurities. It is difficult to directly prepare in industry from lithium ores or lithium-containing brines. Considering comprehensively, using sub-grade industrial lithium carbonate as raw material and producing battery-grade lithium carbonate by a reasonable purification method is the most economical and feasible solution at present. The common methods for purifying lithium carbonate include causticization method, lithium carbonate recrystallization method, hydrogenation precipitation method and hydrogenation decomposition method. Among them, the hydrogenation decomposition method is the first choice for large-scale industrial production.

[0004] The Chinese utility model patent application with the publication number of CN 101863496 A discloses a method for purifying and preparing battery-grade lithium carbonate from industrial-grade lithium carbonate. The industrial-grade lithium carbonate is mixed with water to form a slurry, and an organic acid is gradually added dropwise to convert lithium carbonate into a soluble clear liquid, and then an aqueous urea solution is added to volatilize carbon dioxide gas, thereby generating a lithium carbonate precipitate.

[0005] However, the above technical solution and the existing technologies have the following defects:

[0006] 1. This purification method is only applicable to the laboratory preparation of battery-grade lithium carbonate. The relevant pH value and temperature are difficult to control and cannot be put into industrial production;

[0007] 2. The main raw material of this technical solution is industrial-grade lithium carbonate, and an organic acid needs to be added during the production process to completely dissolve lithium carbonate. The organic acid consumed is dangerous to use and has poor economy, and it is difficult to be popularized on a large scale;

[0008] 3. The carbon dioxide in the production process of lithium bicarbonate is mainly provided by the hydrolysis of urea. It is difficult to control the heat generated by the hydrolysis of urea during large-scale production. At the same time, the carbon dioxide generated by hydrolysis will bring new impurities to lithium bicarbonate, and the produced products are difficult to meet the high-quality requirements of battery grade. Summary of the Utility Model

[0009] The purpose of this section is to outline some aspects of the embodiments of the present utility model and briefly introduce some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and the title of the present application, and such simplifications or omissions shall not be used to limit the scope of the present utility model.

[0010] In view of the above and / or problems existing in the prior art, the present utility model is proposed.

[0011] The purpose of the present utility model is to overcome the problems existing in the prior art and provide a system for producing battery-grade lithium carbonate by hydrogenation decomposition method, which can achieve efficient purification of wet industrial-grade lithium carbonate, make the produced lithium carbonate reach battery-grade purity, improve the yield and production efficiency of lithium carbonate, and reduce material and energy consumption.

[0012] To solve the above technical problems, a system for producing battery-grade lithium carbonate by hydrogenation decomposition method of the present utility model includes a raw material buffer tank for accommodating lithium carbonate slurry. The outlet of the raw material buffer tank is connected to the circulation pipe of a carbonation bubbling tower through a raw material feed pump. The circulation pipe of the carbonation bubbling tower is also connected to a lithium bicarbonate three-stage filtration and impurity removal unit through a carbonation discharge pump. The filtrate outlet of the lithium bicarbonate three-stage filtration and impurity removal unit is connected to the circulation pipe of a pyrolysis crystallizer. The crystal slurry outlet of the pyrolysis crystallizer is connected to the inlet of a pyrolysis thickener through a lithium carbonate crystal slurry pump. The solid phase outlet of the pyrolysis thickener is connected to the inlet of a centrifuge. The solid phase outlet of the centrifuge is connected to the inlet of a product fluidized bed. The discharge outlet of the product fluidized bed is connected to a battery-grade lithium carbonate conveying pipe.

[0013] Further, the outlet of the industrial-grade lithium carbonate conveying pipe is connected to the inlet of a product feeding station. The outlet of the product feeding station is connected to the material inlet of a proportioning and metering tank through a weighed material pipe. The outlet of a clean mother liquor pipe is connected to the mother liquor inlet of the proportioning and metering tank. The outlet of the proportioning and metering tank is connected to the inlet of the raw material buffer tank.

[0014] Further, the outlet of the raw material feed pump is connected to the outlet of a primary carbonation circulation pump through a raw material buffer outlet pipe. The outlet circulation pipe of the primary carbonation circulation pump is connected to the bottom inlet of the tube side of a primary carbonation cooler. The upper outlet of the tube side of the primary carbonation cooler is connected to the reaction liquid inlet of a primary carbonation bubbling tower. The reaction liquid outlet at the bottom of the primary carbonation bubbling tower is connected to the inlet of the primary carbonation circulation pump through a primary carbonation circulation pipe.

[0015] Further, the primary carbonization circulation pipe is also connected to the outlet of the secondary carbonization circulation pump through a carbonization transfer pipe. The outlet circulation pipe of the secondary carbonization circulation pump is connected to the bottom inlet of the tube side of the secondary carbonization cooler. The upper outlet of the tube side of the secondary carbonization cooler is connected to the reaction liquid inlet of the secondary carbonization bubbling tower. The reaction liquid outlet at the bottom of the secondary carbonization bubbling tower is connected to the inlet of the secondary carbonization circulation pump through a secondary carbonization circulation pipe.

[0016] Further, the circulating water inlet pipe is connected to the inlet of the shell side of the secondary carbonization cooler. The outlet of the shell side of the secondary carbonization cooler is connected to the inlet of the shell side of the primary carbonization cooler through a circulating water transfer pipe. The outlet of the shell side of the primary carbonization cooler is connected to the circulating water return pipe.

[0017] Further, the primary carbonization circulation pipe and the secondary carbonization circulation pipe are respectively connected to the inlet of the carbonization discharge pump through a lithium bicarbonate discharge pipe. The outlet of the carbonization discharge pump is connected to the inlet of the plate and frame filter press. The filtrate outlet of the plate and frame filter press is connected to the inlet of the primary filtrate tank. The outlet of the primary filtrate tank is connected to the inlet of the precision filter through a primary filter pump. The filtrate outlet of the precision filter is connected to the inlet of the secondary filtrate tank. The middle part of the secondary filtrate conveying pipe is provided with a pipeline iron remover. The outlet of the cation exchange resin tank is connected to the inlet of the tertiary filtrate tank.

[0018] Further, the outlet of the tertiary filtrate tank is connected to the cold side inlet of the condensate preheater through a tertiary clear liquid pump. The cold side outlet of the condensate preheater is connected to the circulation pipe of the pyrolysis crystallizer. The pyrolysis crystallizer includes two units connected in parallel. The shell side steam inlets of the two pyrolysis heaters are respectively connected to the heating steam pipe. The shell side condensate outlets of the two pyrolysis heaters are respectively connected to the condensate tank. The outlet of the condensate tank is connected to the hot side inlet of the condensate preheater through a condensate external transfer pump. The hot side outlet of the condensate preheater is connected to the condensate collection pipe.

[0019] Further, the mother liquid outlets of the pyrolysis thickening tank and the centrifuge are both connected to the centrifugal mother liquid tank. The bottom outlet of the centrifugal mother liquid tank is connected to the raw material buffer pool. The overflow outlet of the centrifugal mother liquid tank is connected to the inlet of the centrifugal clear liquid tank. The outlet of the centrifugal clear liquid tank is connected to the hot side inlet of the discharge preheater through a centrifugal clear liquid pump and a clean mother liquid discharge pipe. The hot side outlet of the discharge preheater is connected to the mother liquid inlet of the proportioning and metering tank through a clean mother liquid pipe. The cold side outlet of the condensate preheater is connected to the cold side inlet of the discharge preheater. The cold side outlet of the discharge preheater is connected to the circulation pipe of the pyrolysis crystallizer.

[0020] Further, the cold-side outlet of the discharge preheater is connected to the inlet pipeline of the first pyrolysis heater circulation pump. The outlet of the first pyrolysis heater circulation pump is connected to the lower-end inlet of the tube side of the first pyrolysis heater. The upper-end outlet of the tube side of the first pyrolysis heater is connected to the feed liquid inlet of the first pyrolysis crystallizer. The feed liquid outlet of the first pyrolysis crystallizer is connected to the inlet of the first pyrolysis heater circulation pump through the first pyrolysis heater circulation pipe;

[0021] The cold-side outlet of the discharge preheater is also connected to the inlet pipeline of the second pyrolysis heater circulation pump. The outlet of the second pyrolysis heater circulation pump is connected to the lower-end inlet of the tube side of the second pyrolysis heater. The upper-end outlet of the tube side of the second pyrolysis heater is connected to the feed liquid inlet of the second pyrolysis crystallizer. The feed liquid outlet of the second pyrolysis crystallizer is connected to the inlet of the second pyrolysis heater circulation pump through the second pyrolysis heater circulation pipe.

[0022] Further, the tops of all storage tank devices are connected to the tail gas main pipe. The outlet of the tail gas main pipe is connected to the air inlet of the tail gas scrubbing tower through an induced draft fan. The scrubbing mother liquid outlet of the tail gas scrubbing tower is connected to the raw material buffer tank; the water replenishment port of the tail gas scrubbing tower is connected to the circulating water return pipe.

[0023] Compared with the prior art, the utility model has achieved the following beneficial effects: 1. The utility model realizes the efficient purification of wet industrial-grade lithium carbonate, increases the purity of lithium carbonate from 97% to over 99.5%, reduces sodium, magnesium, calcium, potassium and other ions to the standard content, and the product quality meets the requirements of the qualified product of YS / T 582-2013 "Battery-grade Lithium Carbonate", reaching the selling grade.

[0024] The utility model systematically designs a lithium carbonate metering and feeding unit, a lithium carbonate carbonation bubbling unit, a lithium bicarbonate three-stage filtration and impurity removal unit, a lithium bicarbonate two-stage preheating unit, a pyrolysis crystallizer precipitation unit, a secondary mother liquid tank separation unit and a tail gas scrubbing unit according to the physical and chemical properties of the materials and the requirements of industrial production, aiming at the particularity of lithium carbonate materials; reasonably utilizes the solubility laws of lithium carbonate and lithium bicarbonate at different temperatures to improve the purity and efficiency of the generated lithium carbonate and avoid the influence of impurity ions in the solution.

[0025] The industrial-grade lithium carbonate product containing a small amount of lithium hydroxide is metered and then stirred and blended with the low-temperature clean mother liquid from the downstream to form a lithium carbonate slurry, which enters the raw material buffer tank for storage and buffering, accelerating the proportioning efficiency of the upstream proportioning metering tank. The raw material buffer tank also receives the high-solid mother liquid from the bottom of the centrifugal mother liquid tank and the liquid-containing drainage from the tail gas scrubbing tower, which can increase the flexibility of the system operation, effectively store the lithium carbonate-containing mother liquid produced by upstream and downstream production, and ensure that lithium ions do not leak out.

[0026] 4. The lithium carbonate slurry enters the first-stage carbonation bubble column and reacts with high-purity carbon dioxide. The slightly water-soluble solid lithium carbonate reacts with carbon dioxide to form soluble lithium bicarbonate. After the reaction for a period of time, the slurry becomes clear, and the non-carbonated impurities can be removed by filtration. The obtained pure filtrate is then heated with stirring to remove carbon dioxide, and thus purer lithium carbonate slowly precipitates. The two-stage series carbonation effectively improves the efficiency of converting lithium carbonate into lithium bicarbonate and avoids discharging the liquid containing insoluble lithium carbonate solid particles. The carbonation reaction temperature is controlled at room temperature by an external carbonation cooler to achieve cyclic carbonation, and the lithium-containing feed liquid is regularly discharged to the second-stage carbonation circulation pipe to enter the next carbonation cycle.

[0027] 5. The present utility model designs a series double-carbonation bubble column system, which rationally distributes carbon dioxide by using the air-lift pipe in the bubble column. The carbon dioxide injection port in the air-lift pipe is designed to be conical and is sleeved with an anti-corrosion conical rubber sleeve, effectively avoiding the backmixing of the reaction liquid. A gas flow-limiting orifice plate is arranged at the top of the air-lift pipe to increase the utilization efficiency of carbon dioxide. A wire mesh demister is arranged at the top of the carbonation bubble column to effectively prevent the carbon dioxide from entraining the reaction liquid and discharging it.

[0028] 6. The carbonated lithium bicarbonate reaction liquid is sequentially filtered and purified through a plate-and-frame filter press, a precision filter, and a cation exchange resin tank in three stages. Among them, the first-stage plate-and-frame filter press removes the mud and insoluble impurities in the feed liquid; the second-stage precision filter removes the oil film and particulate impurities in the feed liquid; the third-stage cation exchange resin tank removes the impurity ions such as calcium and magnesium in the feed liquid, making the product lithium carbonate meet the requirements of ≤0.005% for calcium ions and ≤0.008% for magnesium ions in battery-grade lithium carbonate. In addition, a pipeline electromagnetic separator is arranged in the filtration system to remove the ferromagnetic impurities in the feed liquid, making the product lithium carbonate meet the requirement of ≤0.0003% for ferromagnetic solids in battery-grade lithium carbonate.

[0029] 7. The present utility model designs a second-stage preheating system. The clean lithium bicarbonate feed liquid after filtration is preheated through a condensate preheater and a discharge preheater in sequence. Among them, the hot-side medium of the condensate preheater is the hot-side condensate water of the pyrolysis heater; the hot-side medium of the discharge preheater is the clean mother liquor after centrifugation. This system rationally utilizes the residual heat of the condensate water and the clean mother liquor in the pyrolysis heater, reduces the steam consumption of the pyrolysis heater, and saves the energy consumption of the device.

[0030] 8. The solubility of lithium carbonate decreases with the increase of temperature, while the solubility of most impurities increases with the increase of temperature. Increasing the pyrolysis reaction temperature can accelerate the pyrolysis rate and increase the driving force for lithium carbonate crystallization. However, too high a pyrolysis temperature will increase the heat load of the device production and increase the material cost of the reaction equipment. Therefore, in order to improve the pyrolysis reaction rate, reduce production costs and control the wall sticking phenomenon, the optimal pyrolysis reaction temperature is maintained at 90 °C. The parallel pyrolysis crystallizer system uses heating steam as the heat source for the pyrolysis heater to maintain the temperature of the reaction liquid in the pyrolysis crystallizer at 90 °C.

[0031] 9. The lithium bicarbonate solution that has been filtered and preheated enters the pyrolysis crystallizer through the pyrolysis heater circulation pipe, and through the frame type stirring rotor and heating decomposition, lithium carbonate precipitate and carbon dioxide are generated and overflowed for recycling. A frame type stirring rotor is set in the pyrolysis crystallizer to ensure the pyrolysis efficiency of lithium bicarbonate in the pyrolysis crystallizer and effectively avoid the "wall sticking" phenomenon of lithium carbonate. When the solid-liquid ratio of the crystal slurry at the bottom of the pyrolysis crystallizer reaches 20%, it is sent to the downstream pyrolysis thickening tank through the lithium carbonate crystal slurry pipe. Carbon dioxide is regularly introduced into the pyrolysis crystallizer from the bottom for carbonization to avoid the adhesion of lithium carbonate inside the pyrolysis crystallizer.

[0032] 10. The present utility model designs a secondary mother liquor tank separation unit. The liquid material at the outlet of the centrifuge enters the centrifugal mother liquor tank for solid precipitation. The lithium carbonate solution with a higher solid content enters the raw material buffer tank from the bottom for slurry supplementation to avoid the waste of lithium ions flowing out. The lithium carbonate clear liquid with a lower solid content overflows from the top into the centrifugal clear liquid tank, provides heat source for the discharge preheater, and finally enters the proportioning and metering tank to participate in the preparation of lithium carbonate. By setting the secondary mother liquor tank, the mother liquor is classified according to the solid content, effectively utilizing the mother liquor preheating and avoiding the risk of preheater blockage. Description of the Drawings

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to these drawings. The drawings are only for reference and explanation, and are not used to limit the present utility model. Among them:

[0034] Figure 1 is the flow chart of the system for producing battery-grade lithium carbonate by the hydrogenation decomposition method of the present utility model;

[0035] Figure 2 is the cross-sectional view of the carbonization bubbling tower of the present utility model;

[0036] Figure 3 is the three-dimensional view of the carbonization bubbling tower of the present utility model;

[0037] Figure 4 It is a three-dimensional view of the carbon dioxide riser in the carbonization bubbling tower;

[0038] Figure 5 It is a sectional view of the pyrolysis crystallizer in the present utility model;

[0039] Figure 6 It is a three-dimensional view of the pyrolysis crystallizer in the present utility model;

[0040] In the figure: 1. Product feeding station; 2. Ratio metering tank; 3. Raw material buffer tank; 4. Centrifugal mother liquor tank; 5. Centrifugal clear liquid tank; 6. Induced draft fan; 7. Tail gas scrubbing tower; 8. First-stage carbonization cooler; 9. First-stage carbonization bubbling tower; 10. Second-stage carbonization cooler; 11. Second-stage carbonization bubbling tower; 12. Plate and frame filter press; 13. First-stage filtrate tank; 14. Precision filter; 15. Second-stage filtrate tank; 16. Pipeline iron remover; 17. Cation exchange resin tank; 18. Third-stage filtrate tank; 19. Condensate preheater; 20. Discharge preheater; 21. First pyrolysis heater; 22. First pyrolysis crystallizer; 23. Second pyrolysis heater; 24. Second pyrolysis crystallizer; 25. Condensate tank; 26. Pyrolysis thickening tank; 27. Centrifuge; 28. Product fluidized bed;

[0041] Carbonization bubbling tower: 9a. Carbon dioxide outlet at the top of the tower; 9b. Mesh demister in the bubbling tower; 9c. Gas flow limiting orifice plate; 9d. Reaction liquid inlet of the bubbling tower; 9e. Riser fixing column; 9f. Carbon dioxide injection port; 9g. Carbon dioxide riser; 9h. Carbon dioxide inlet nozzle; 9j. Reaction liquid outlet of the bubbling tower;

[0042] Pyrolysis crystallizer: 22a. Stirring motor; 22b. Carbon dioxide outlet of the crystallizer; 22c. Hot water inlet; 22d. Stirring shaft; 22e. Heating and insulation coil; 22f. Feed liquid inlet of the crystallizer; 22g. Frame type stirring rotor; 22h. Hot water outlet; 22j. Feed liquid outlet of the crystallizer; 22k. Carbon dioxide inlet of the crystallizer; 22m. Salt leg of the crystallizer; 22n. Crystal slurry outlet; 22p. Crystal slurry sewage discharge port; 22q. Crystal mesh demister;

[0043] B1. Buffer tank sewage pump; B2. Raw material feed pump; B3. Centrifugal clear liquid pump; B4. First-stage carbonization circulation pump; B5. Second-stage carbonization circulation pump; B6. Carbonization discharge pump; B7. Second-stage filtration pump; B8. Condensate external transfer pump; B9. First pyrolysis heater circulation pump; B10. Second pyrolysis heater circulation pump; B11. Lithium carbonate crystal slurry pump; B12. Third-stage clear liquid pump; B13. First-stage filtration pump;

[0044] G1. Industrial-grade lithium carbonate delivery pipe; G2. Weighing material pipe; G3. Clean mother liquor pipe; G4. Buffer tank feed pipe; G5. Scrubber discharge pipe; G6. Solid-containing mother liquor discharge pipe; G7. Centrifuged mother liquor overflow pipe; G8. Clean mother liquor discharge pipe; G9. Raw material buffer outlet pipe; G10. Tail gas main pipe; G11. Circulating water return pipe; G12. First-stage carbonation circulation pipe; G13. Circulating water transfer pipe; G14. Carbonation transfer pipe; G15. Circulating water inlet pipe; G16. Second-stage carbonation circulation pipe; G17. Bubbling tower carbon dioxide discharge pipe; G18. Lithium bicarbonate discharge pipe; G19. First-stage filtrate delivery pipe; G20. Second-stage filtrate delivery pipe; G21. Third-stage clear liquid delivery pipe; G22. First pyrolysis heater circulation pipe; G23. Second pyrolysis heater circulation pipe; G24. Condensate delivery pipe; G25. Lithium carbonate crystal slurry pipe; G26. Lithium carbonate mother liquor pipe; G27. Centrifuge discharge pipe; G28. Battery-grade lithium carbonate delivery pipe; G29. Heating steam pipe; G30. Pyrolysis carbon dioxide discharge pipe; G31. Bubbling tower carbon dioxide supply pipe; G32. Buffer tank sewage discharge pipe. Detailed implementation manners

[0045] 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.

[0046] 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.

[0047] 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.

[0048] As Figure 1 shown, the system for producing battery-grade lithium carbonate by the hydrogenation decomposition method of the present utility model includes a lithium carbonate metering and feeding unit, a lithium carbonate carbonation bubbling unit, a lithium bicarbonate three-stage filtration and impurity removal unit, a lithium bicarbonate two-stage preheating unit, a pyrolysis crystallizer precipitation unit, a second-stage mother liquor tank separation unit, and a tail gas scrubbing unit connected in sequence.

[0049] The lithium carbonate metering and feeding unit includes a product feeding station 1, a proportioning and metering tank 2, and a raw material buffer tank 3. The inlet of the product feeding station 1 is connected to the outlet of the industrial-grade lithium carbonate conveying pipe G1. The outlet of the product feeding station 1 is connected to the material inlet of the proportioning and metering tank 2 through a weighed material pipe G2. The outlet of the clean mother liquor pipe G3 is connected to the mother liquor inlet of the proportioning and metering tank 2. The outlet of the proportioning and metering tank 2 is connected to the inlet of the raw material buffer tank 3 through a buffer tank feed pipe G4.

[0050] The bottom drain outlet of the raw material buffer tank 3 is connected to the inlet of the buffer tank drain pump B1. The outlet of the buffer tank drain pump B1 is connected to a buffer tank drain pipe G32 for discharging the dirt at the bottom.

[0051] The lithium carbonate carbonization and bubbling unit includes a raw material feed pump B2, a primary carbonization cooler 8, a primary carbonization bubbling tower 9, a primary carbonization circulation pump B4, a secondary carbonization cooler 10, a secondary carbonization bubbling tower 11, and a secondary carbonization circulation pump B5. The liquid outlet of the raw material buffer tank 3 is connected to the inlet of the raw material feed pump B2. The outlet of the raw material feed pump B2 is connected to the outlet of the primary carbonization circulation pump B4 through a raw material buffer outlet pipe G9.

[0052] The outlet circulation pipe of the primary carbonization circulation pump B4 is connected to the bottom inlet of the tube side of the primary carbonization cooler 8. The upper outlet of the tube side of the primary carbonization cooler 8 is connected to the reaction liquid inlet of the primary carbonization bubbling tower 9. The reaction liquid outlet at the bottom of the primary carbonization bubbling tower 9 is connected to the inlet of the primary carbonization circulation pump B4 through a primary carbonization circulation pipe G12.

[0053] The primary carbonization circulation pipe G12 is also connected to the outlet of the secondary carbonization circulation pump B5 through a carbonization transfer pipe G14. The outlet circulation pipe of the secondary carbonization circulation pump B5 is connected to the bottom inlet of the tube side of the secondary carbonization cooler 10. The upper outlet of the tube side of the secondary carbonization cooler 10 is connected to the reaction liquid inlet of the secondary carbonization bubbling tower 11. The reaction liquid outlet at the bottom of the secondary carbonization bubbling tower 11 is connected to the inlet of the secondary carbonization circulation pump B5 through a secondary carbonization circulation pipe G16.

[0054] The carbon dioxide inlets of both the primary carbonization bubbling tower 9 and the secondary carbonization bubbling tower 11 are connected to a bubbling tower carbon dioxide supply pipe G31. The carbon dioxide outlets at the tops of the primary carbonization bubbling tower 9 and the secondary carbonization bubbling tower 11 are connected to a bubbling tower carbon dioxide discharge pipe G17 to recover the overflowing carbon dioxide for reuse.

[0055] The circulating water inlet pipe G15 is connected to the inlet of the shell side of the secondary carbonization cooler 10. The outlet of the shell side of the secondary carbonization cooler 10 is connected to the inlet of the shell side of the primary carbonization cooler 8 through a circulating water transfer pipe G13. The outlet of the shell side of the primary carbonization cooler 8 is connected to a circulating water return pipe G11.

[0056] The lithium bicarbonate three-stage filtration and impurity removal unit includes a carbonation discharge pump B6, a plate and frame filter press 12, a first-stage filtrate tank 13, a first-stage filtration pump B13, a precision filter 14, a second-stage filtrate tank 15, a second-stage filtration pump B7, a pipeline iron remover 16, a cation exchange resin tank 17, and a third-stage filtrate tank 18. The first-stage carbonation circulation pipe G12 and the second-stage carbonation circulation pipe G16 are also respectively connected to the inlet of the carbonation discharge pump B6 through the lithium bicarbonate discharge pipe G18. The outlet of the carbonation discharge pump B6 is connected to the inlet of the plate and frame filter press 12. The filtrate outlet of the plate and frame filter press 12 is connected to the inlet of the first-stage filtrate tank 13 through the first-stage filtrate delivery pipe G19. The outlet of the first-stage filtrate tank 13 is connected to the inlet of the first-stage filtration pump B13. The outlet of the first-stage filtration pump B13 is connected to the inlet of the precision filter 14. The filtrate outlet of the precision filter 14 is connected to the inlet of the second-stage filtrate tank 15. The outlet of the second-stage filtrate tank 15 is connected to the inlet of the second-stage filtration pump B7. The outlet of the second-stage filtration pump B7 is connected to the inlet of the cation exchange resin tank 17 through the second-stage filtrate delivery pipe G20. A pipeline iron remover 16 is provided in the middle of the second-stage filtrate delivery pipe G20. The outlet of the cation exchange resin tank 17 is connected to the inlet of the third-stage filtrate tank 18.

[0057] The lithium bicarbonate second-stage preheating unit includes a third-stage clear liquid pump B12, a condensate preheater 19, and a discharge preheater 20. The outlet of the third-stage filtrate tank 18 is connected to the inlet of the third-stage clear liquid pump B12. The outlet of the third-stage clear liquid pump B12 is connected to the cold-side inlet of the condensate preheater 19. The hot-side inlet of the condensate preheater 19 is connected to the outlet of the condensate delivery pipe G24. The hot-side outlet of the condensate preheater 19 is connected to the condensate collection pipe.

[0058] The cold-side outlet of the condensate preheater 19 is connected to the cold-side inlet of the discharge preheater 20. The cold-side outlet of the discharge preheater 20 is connected to the third-stage clear liquid delivery pipe G21. The clean mother liquor discharge pipe G8 is connected to the hot-side inlet of the discharge preheater 20. The hot-side outlet of the discharge preheater 20 is connected to the clean mother liquor pipe G3.

[0059] The pyrolysis crystallization precipitator unit includes a first pyrolysis heater circulation pump B9, a first pyrolysis heater 21, a first pyrolysis crystallizer 22, a second pyrolysis heater circulation pump B10, a second pyrolysis heater 23, a second pyrolysis crystallizer 24, a condensate tank 25, a lithium carbonate crystal slurry pump B11, a pyrolysis thickener 26, a centrifuge 27, and a product fluidized bed 28.

[0060] The outlet of the tertiary clarified liquid transfer pipe G21 is connected to the inlet pipe of the first pyrolysis heater circulation pump B9. The outlet of the first pyrolysis heater circulation pump B9 is connected to the lower inlet of the tube side of the first pyrolysis heater 21. The upper outlet of the tube side of the first pyrolysis heater 21 is connected to the feed liquid inlet of the first pyrolysis crystallizer 22. The feed liquid outlet of the first pyrolysis crystallizer 22 is connected to the inlet of the first pyrolysis heater circulation pump B9 through the first pyrolysis heater circulation pipe G22.

[0061] The outlet of the tertiary clarified liquid transfer pipe G21 is also connected to the inlet pipe of the second pyrolysis heater circulation pump B10. The outlet of the second pyrolysis heater circulation pump B10 is connected to the lower inlet of the tube side of the second pyrolysis heater 23. The upper outlet of the tube side of the second pyrolysis heater 23 is connected to the feed liquid inlet of the second pyrolysis crystallizer 24. The feed liquid outlet of the second pyrolysis crystallizer 24 is connected to the inlet of the second pyrolysis heater circulation pump B10 through the second pyrolysis heater circulation pipe G23.

[0062] The shell side steam inlets of the first pyrolysis heater 21 and the second pyrolysis heater 23 are respectively connected to the heating steam pipe G29. The shell side condensate outlets of the first pyrolysis heater 21 and the second pyrolysis heater 23 are respectively connected to the inlet of the condensate tank 25. The outlet of the condensate tank 25 is connected to the inlet of the condensate transfer pump B8. The outlet of the condensate transfer pump B8 is connected to the hot side inlet of the condensate preheater 19 through the condensate transfer pipe G24.

[0063] The carbon dioxide outlets of the first pyrolysis crystallizer 22 and the second pyrolysis crystallizer 24 are respectively connected to the pyrolysis carbon dioxide discharge pipe G30.

[0064] The slurry outlets of the first pyrolysis crystallizer 22 and the second pyrolysis crystallizer 24 are respectively connected to the lithium carbonate slurry pipe G25. The outlet of the lithium carbonate slurry pipe G25 is connected to the inlet of the lithium carbonate slurry pump B11. The outlet of the lithium carbonate slurry pump B11 is connected to the inlet of the pyrolysis thickener 26. The solid phase outlet of the pyrolysis thickener 26 is connected to the inlet of the centrifuge 27. The solid phase outlet of the centrifuge 27 is connected to the inlet of the product fluidized bed 28 through the centrifuge discharge pipe G27. The discharge outlet of the product fluidized bed 28 is connected to the battery grade lithium carbonate transfer pipe G28.

[0065] The secondary mother liquor tank separation unit includes a centrifugal mother liquor tank 4 and a centrifugal clear liquor tank 5. The mother liquor outlets of the pyrolysis thickening tank 26 and the centrifuge 27 are respectively connected to the inlet of the centrifugal mother liquor tank 4 through the lithium carbonate mother liquor pipe G26. The bottom outlet of the centrifugal mother liquor tank 4 is connected to the reflux port of the raw material buffer tank 3 through the solid-containing mother liquor discharge pipe G6. The overflow outlet of the centrifugal mother liquor tank 4 is connected to the inlet of the centrifugal clear liquor tank 5 through the centrifugal mother liquor overflow pipe G7. The outlet of the centrifugal clear liquor tank 5 is connected to the inlet of the centrifugal clear liquor pump B3. The outlet of the centrifugal clear liquor pump B3 is connected to the hot-side inlet of the discharge preheater 20 through the clean mother liquor discharge pipe G8. The hot-side outlet of the discharge preheater 20 is connected to the mother liquor inlet of the proportioning and metering tank 2 through the clean mother liquor pipe G3.

[0066] The industrial-grade wet lithium carbonate is transported to the product feeding station 1 through the industrial-grade lithium carbonate conveying pipe G1. After being metered by the product feeding station 1, the industrial-grade lithium carbonate product containing a small amount of lithium hydroxide is transported to the proportioning and metering tank 2 through the weighed material pipe G2. The low-temperature clean mother liquor from the downstream is transported to the proportioning and metering tank 2 through the clean mother liquor pipe G3 for proportioning. After stirring and proportioning, a lithium carbonate slurry is formed, which enters the raw material buffer tank 3 through the buffer tank feed pipe G4 for storage and buffering, accelerating the proportioning efficiency of the upstream proportioning and metering tank 2. In addition, the raw material buffer tank 3 also receives the high-solid-containing mother liquor from the bottom of the centrifugal mother liquor tank 4 and the liquid-containing drainage from the tail gas scrubbing tower 7.

[0067] The lithium carbonate slurry after proportioning and buffering is pumped out by the raw material feed pump B2 and sent to the carbonization system through the raw material buffer outlet pipe G9 for the next operation.

[0068] The lithium carbonate raw material from the raw material buffer outlet pipe G9 is injected into the primary carbonization circulation pipe G12. After being mixed with the circulating liquid sent out by the primary carbonization circulation pump B4, it enters the tube side of the primary carbonization cooler 8 for cooling. After cooling, it enters the primary carbonization bubbling tower 9 for carbonization reaction. The clean carbon dioxide gas is supplemented to the primary carbonization bubbling tower 9 through the bubbling tower carbon dioxide supplement pipe G31.

[0069] In the primary carbonization bubbling tower 9, solid lithium carbonate and part of lithium hydroxide react with carbon dioxide at room temperature to form soluble lithium bicarbonate. Since the carbonization reaction needs to maintain room temperature, the primary carbonization reaction materials are transported to the tube side of the primary carbonization cooler 8 through the primary carbonization circulation pipe G12 and the primary carbonization circulation pump B4 for circulating cooling.

[0070] The lithium-containing feed liquid generated by the partial primary carbonation bubbling tower 9 is sent into the secondary carbonation circulation pipe G16 through the carbonation transfer pipe G14, enters the next carbonation cycle, mixes with the circulating liquid sent out by the secondary carbonation circulation pump B5, enters the tube side of the secondary carbonation cooler 10 for cooling, and after cooling, enters the secondary carbonation bubbling tower 11 for carbonation reaction again. Clean carbon dioxide gas is supplemented to the secondary carbonation bubbling tower 11 through the bubbling tower carbon dioxide supplement pipe G31. The two-stage carbonation system forms a series connection, enabling lithium carbonate to fully react with carbon dioxide, effectively improving the efficiency of converting lithium carbonate into lithium bicarbonate, and avoiding the discharged feed liquid containing insoluble lithium carbonate solid particles.

[0071] The secondary carbonation reaction materials are transported to the tube side of the secondary carbonation cooler 10 through the secondary carbonation circulation pipe G16 and the secondary carbonation circulation pump B5 for circulating cooling. The cooling medium for the shell side of the secondary carbonation cooler 10 is the utility engineering circulating cooling water from the circulating water inlet pipe G15. After flowing through the shell side of the secondary carbonation cooler 10 for heat exchange, it enters the shell side of the primary carbonation cooler 8 through the circulating water transfer pipe G13 for continuous heat exchange, and after heating up, it returns to the cooling system for circulating cooling through the circulating water return pipe G11.

[0072] When the lithium content of the carbonated material reaches 8.5 g / L, the qualified lithium bicarbonate material is sent out by the carbonation discharge pump B6, and is sent to the plate and frame filter press 12 through the lithium bicarbonate discharge pipe G18 for primary filtration to remove the slurry and insoluble impurities in the feed liquid. The primary filtrate enters the primary filtrate tank 13 for storage through the primary filtrate transfer pipe G19.

[0073] The primary filtrate is sent to the precision filter 14 by the primary filtration pump B13 to remove the oil film and particulate impurities in the feed liquid and improve the product quality. The secondary filtrate enters the secondary filtrate tank 15 for storage.

[0074] The secondary filtrate is pumped out by the secondary filtration pump B7, and is sent to the pipeline magnetic separator 16 through the secondary filtrate transfer pipe G20 to remove the ferromagnetic impurities in the feed liquid and further increase the lithium content, so that the product lithium carbonate meets the requirement of ferromagnetic solids ≤ 0.0003% in battery-grade lithium carbonate. Then it enters the cation exchange resin tank 17 to remove the impurity ions such as calcium and magnesium in the incoming liquid, so that the product lithium carbonate meets the requirements of calcium ions ≤ 0.005% and magnesium ions ≤ 0.008% in battery-grade lithium carbonate. The tertiary filtrate enters the tertiary filtrate tank 18 for storage.

[0075] The lithium bicarbonate solution after three-stage impurity removal is sent to the cold side of the condensate preheater 19 by the tertiary clear liquid pump B12 for primary preheating. The primary preheating medium is the hot side condensate of the pyrolysis heater from the condensate transfer pipe G24.

[0076] The solution after primary preheating enters the cold side of the discharge preheater 20 for secondary preheating. The secondary preheating medium is the centrifuged clean mother liquor from the clean mother liquor discharge pipe G8. After heat exchange and temperature reduction, it enters the proportioning and metering tank 2 through the clean mother liquor pipe G3 for slurry preparation, making full use of the residual heat of the device and reducing energy consumption.

[0077] The lithium bicarbonate solution after secondary preheating enters the first pyrolysis crystallizer 22 and the second pyrolysis crystallizer 24 through the tertiary clear liquid transfer pipe G21 for pyrolysis reaction. To accelerate the reaction efficiency, frame-type stirring rotors are equipped at the lower center of the first pyrolysis crystallizer 22 and the second pyrolysis crystallizer 24, and the stirring rate is maintained at 300 rpm, effectively avoiding the phenomenon of lithium carbonate "sticking to the wall". Lithium bicarbonate is heated to form lithium carbonate precipitate and carbon dioxide, and the carbon dioxide overflows and is recovered through the pyrolysis carbon dioxide discharge pipe G30 at the top of the two pyrolysis crystallizers.

[0078] To maintain the reaction rate of lithium bicarbonate and reduce the content of impurity ions, the pyrolysis temperature needs to be maintained at 90 ± 2 °C. The reaction solution discharged from the lower conical wall of the first pyrolysis crystallizer 22 enters the first pyrolysis heater circulation pipe G22, and is sent to the tube side of the first pyrolysis heater 21 by the first pyrolysis heater circulation pump B9 for heating and then returns to the first pyrolysis crystallizer 22 for circulation.

[0079] The reaction solution discharged from the lower conical wall of the second pyrolysis crystallizer 24 enters the second pyrolysis heater circulation pipe G23, and is sent to the tube side of the second pyrolysis heater 23 by the second pyrolysis heater circulation pump B10 for heating and then returns to the second pyrolysis crystallizer 24 for circulation.

[0080] The heating medium for the shell side of the first pyrolysis heater 21 and the second pyrolysis heater 23 is steam and is supplemented by the heating steam pipe G29. The steam condensate formed after heat exchange enters the condensate tank 25 for collection, and is then sent out by the condensate external transfer pump B8. It enters the hot side of the condensate preheater 19 through the condensate transfer pipe G24 to preheat the lithium bicarbonate solution after three-stage filtration and impurity removal.

[0081] When the solid-liquid ratio of the crystal slurry at the bottom of the first pyrolysis crystallizer 22 and the second pyrolysis crystallizer 24 reaches 20%, it is discharged through the lithium carbonate crystal slurry pipe G25 and sent to the pyrolysis thickening tank 26 by the lithium carbonate crystal slurry pump B11. After thickening and precipitation, it is sent to the centrifuge 27 for solid-liquid separation. The separated white lithium carbonate crystals have a high water content and are discharged through the centrifuge discharge pipe G27 and sent to the product fluidized bed 28 for drying and separation. The content of lithium carbonate crystals reaches more than 99.5% wt, and the final qualified dry lithium carbonate is packed and sent out through the battery-grade lithium carbonate transfer pipe G28.

[0082] To avoid lithium carbonate adhesion inside the pyrolysis crystallizer, carbon dioxide is regularly introduced into the pyrolysis crystallizer from the bottom for carbonization.

[0083] The liquid-phase mother liquor separated by the centrifuge 27 is sent to the centrifugal mother liquor tank 4 through the lithium carbonate mother liquor pipe G26. The mother liquor undergoes solid precipitation in the centrifugal mother liquor tank 4. The lithium carbonate mother liquor with a high solid content is discharged from the bottom of the centrifugal mother liquor tank 4 and enters the raw material buffer tank 3 through the solid-containing mother liquor discharge pipe G6. The supernatant liquid at the upper part of the centrifugal mother liquor tank 4 with a low solid content overflows and enters the centrifugal supernatant liquid tank 5 through the centrifugal mother liquor overflow pipe G7. The drainage of the centrifugal supernatant liquid tank 5 is discharged by the centrifugal supernatant liquid pump B3 and sent to the hot side of the discharge preheater 20 through the clean mother liquor discharge pipe G8 to provide heat source for the discharge preheater. The lithium-containing clear liquid after recovering the waste heat returns to the proportioning and metering tank 2 through the clean mother liquor pipe G3 to participate in the liquid proportioning of product feeding, realizing the efficient utilization of lithium ions.

[0084] The tail gas washing unit includes a draft fan 6 and a tail gas washing tower 7. Tail gas discharge pipes are provided at the tops of the main storage tanks of the device. Each tail gas discharge pipe is respectively connected to the inlet of the tail gas main pipe G10. The outlet of the tail gas main pipe G10 is connected to the inlet of the draft fan 6 for pumping. The tail gas after pumping enters the tail gas washing tower 7. The tail gas washing tower 7 is adsorbed and washed by circulating water. The washing mother liquor is regularly discharged into the raw material buffer tank 3 through the washing tower discharge pipe G5 to avoid the waste of lithium ions flowing out. The flushing water of the tail gas washing tower 7 is regularly supplemented by the circulating water return pipe G11 to ensure that the tail gas discharged from the washing tower does not carry flying salts.

[0085] As Figures 2 to 4 shown, regarding the internal structure of the carbonation bubbling tower, taking the first-stage carbonation bubbling tower 9 as an example, it includes a vertical cylindrical tower body. The inner cavity of the tower body is provided with a coaxial carbon dioxide air-lift pipe 9g. The bottom of the carbon dioxide air-lift pipe 9g is closed. Along the height direction of the carbon dioxide air-lift pipe 9g, at least two supports are provided. Each support is respectively provided with four evenly distributed air-lift pipe fixing columns 9e to support on the inner wall of the tower body. The upper end of the carbon dioxide air-lift pipe 9g extends to the upper part of the tower body and is provided with a gas limiting orifice plate 9c. The lower circumference of the carbon dioxide air-lift pipe 9g is connected with a carbon dioxide inlet nozzle 9h. The outer end of the carbon dioxide inlet nozzle 9h extends to the outside of the tower body. A plurality of carbon dioxide injection nozzles 9f are evenly arranged along the outer circumference and height direction of the carbon dioxide air-lift pipe 9g to uniformly eject carbon dioxide. The upper part of the tower body is provided with an enlarged diameter section. A bubbling tower reaction liquid inlet 9d is provided on the circumferential wall of the enlarged diameter section. The center of the bottom head of the tower body is provided with a bubbling tower reaction liquid outlet 9j. The center of the upper head of the tower body is provided with a tower top carbon dioxide outlet 9a. A bubbling tower wire mesh demister 9b is provided in the upper head of the tower body. The bubbling tower wire mesh demister 9b is located above the gas limiting orifice plate 9c.

[0086] High-purity carbon dioxide make-up gas enters the carbon dioxide air-lift pipe 9g through the carbon dioxide inlet nozzle 9h. The carbon dioxide inlet nozzle 9h keeps the carbon dioxide make-up rate stable above 1.5 m / s and is fixed on the inner wall of the carbonation bubbling tower along the height direction of the carbon dioxide air-lift pipe 9g through multiple air-lift pipe fixing columns 9e. During the upward movement of the high-purity carbon dioxide along the inner cavity of the carbon dioxide air-lift pipe 9g, it is evenly sprayed into the outer peripheral space of the carbon dioxide air-lift pipe 9g through each carbon dioxide injection port 9f distributed on the circumference of the air-lift pipe. The lithium carbonate slurry enters the inner cavity of the carbonation bubbling tower from the bubbling tower reaction liquid inlet 9d and flows downward. Solid lithium carbonate reacts with the counter-flowing carbon dioxide at room temperature to generate soluble lithium bicarbonate, which is discharged from the bubbling tower reaction liquid outlet 9j at the bottom of the tower, circulated and transported by the corresponding circulation pump, and cooled by the carbonation cooler and then returned to the carbon dioxide inlet nozzle 9h for circulation to ensure the carbonation efficiency.

[0087] The carbon dioxide injection port 9f is set in a conical shape and is sleeved with an anti-corrosion conical rubber sleeve at the end. Carbon dioxide sprays out from the tip small hole of the conical rubber sleeve, which can ensure one-way flow and prevent backmixing. The gas flow limiting orifice plate 9c at the top of the carbon dioxide air-lift pipe 9g limits the carbon dioxide discharge rate within 1 m / s. And the bubbling tower wire mesh demister 9b set at the top of the carbonation bubbling tower eliminates the liquid droplets carried in the rising gas, keeps the carbon dioxide clean and dry, and is discharged and recycled through the bubbling tower carbon dioxide discharge pipe G17 after flowing out from the carbon dioxide outlet 9a at the top of the tower.

[0088] As Figure 5 、 Figure 6 shown, regarding the internal structure of the pyrolysis crystallizer, taking the first pyrolysis crystallizer 22 as an example, the main body of the pyrolysis crystallizer is a vertical circular cylinder. A conical upper cylinder is provided at the upper end of the circular cylinder, and a conical lower cylinder is provided at the lower end of the circular cylinder. A crystallizer feed liquid inlet 22f is provided on the lower side wall of the circular cylinder, and a crystallizer carbon dioxide outlet 22b is provided on the side wall of the conical upper cylinder. A crystallizer wire mesh demister 22q is provided on the cross-section below the crystallizer carbon dioxide outlet 22b.

[0089] A stirring shaft 22d is provided along the axis of the circular cylinder. A frame-type stirring rotor 22g is provided at the lower end of the stirring shaft 22d. The upper end of the stirring shaft 22d extends outside the equipment and is connected to the rotor shaft of the stirring motor 22a. The outer circumference of the circular cylinder is wound with a heating and insulation coil 22e. The upper end of the heating and insulation coil 22e is a hot water inlet 22c, and the lower end is a hot water outlet 22h.

[0090] Crystallizer feed liquid outlets 22j and crystallizer carbon dioxide inlets 22k are respectively provided on both sides of the conical wall of the conical lower cylinder. The bottom of the conical lower cylinder is connected to a crystallizer salt leg 22m. A crystal slurry outlet 22n is provided on the lower side wall of the crystallizer salt leg 22m, and a crystal slurry sewage discharge port 22p is provided at the lower end of the crystallizer salt leg 22m.

[0091] The heated recycled liquid material enters the inner cavity of the pyrolysis crystallizer through the crystallizer liquid inlet 22f, and the recycled liquid material after stirring and separation leaves the pyrolysis crystallizer through the crystallizer liquid outlet 22j. The decomposed carbon dioxide gas is de-liquefied through the crystallizing wire mesh demister 22q and then discharged outside through the crystallizer carbon dioxide outlet 22b at the upper part; the lithium carbonate crystal slurry with a higher solid content is deposited in the bottom salt leg 22m and discharged through the crystal slurry outlet 22n, and the bottom precipitate is regularly discharged through the crystal slurry sewage outlet 22p.

[0092] To ensure that the temperature of the crystallizer is maintained at the optimal temperature, the heat preservation hot water enters the heating and insulation coil 22e through the hot water inlet 22c for heat preservation, and the hot water after heat exchange is discharged through the hot water outlet 22h. To ensure the pyrolysis efficiency of lithium bicarbonate, a frame-type stirring rotor 22g is arranged in the inner cavity of the crystallizer and is driven by the top stirring motor 22a through the stirring shaft 22d.

[0093] To prevent the inner wall of the crystallizer and the stirring equipment from sticking with lithium carbonate, clean carbon dioxide is regularly introduced into the crystallizer through the crystallizer carbon dioxide inlet 22k to clean the deposited lithium carbonate inside. At this time, the internal heating and insulation coil 22e needs to be filled with normal temperature circulating water for cooling.

[0094] The above is only the preferred and feasible embodiment of the present utility model, which shows and describes the basic principle, main features and advantages of the present utility model. It does not limit the patent protection scope of the present utility model. Those skilled in the art should understand that the present utility model is not limited by the above embodiments. Except the above embodiments, without departing from the spirit and scope of the present utility model, the present utility model can also have other implementation manners. The present utility model will also have various changes and improvements. All technical solutions formed by equivalent replacement 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 existing technologies and will not be elaborated herein.

Claims

1. A system for producing battery-grade lithium carbonate by hydrogenation decomposition method, including a raw material buffer tank for accommodating lithium carbonate slurry, characterized in that, The outlet of the raw material buffer tank is connected to the circulation pipe of the carbonization bubbling tower through a raw material feeding pump. The circulation pipe of the carbonization bubbling tower is also connected to the lithium bicarbonate three-stage filtration and impurity removal unit through a carbonization discharging pump. The filtrate outlet of the lithium bicarbonate three-stage filtration and impurity removal unit is connected to the circulation pipe of the pyrolysis crystallizer. The crystal slurry outlet of the pyrolysis crystallizer is connected to the inlet of the pyrolysis thickener through a lithium carbonate crystal slurry pump. The solid phase outlet of the pyrolysis thickener is connected to the inlet of the centrifuge. The solid phase outlet of the centrifuge is connected to the inlet of the product fluidized bed. The discharge outlet of the product fluidized bed is connected to the battery-grade lithium carbonate conveying pipe.

2. The system for producing battery-grade lithium carbonate by hydrogenation decomposition method according to claim 1, characterized in that: The outlet of the industrial-grade lithium carbonate conveying pipe is connected to the inlet of the product feeding station. The outlet of the product feeding station is connected to the material inlet of the proportioning and metering tank through a weighing material pipe. The outlet of the clean mother liquor pipe is connected to the mother liquor inlet of the proportioning and metering tank. The outlet of the proportioning and metering tank is connected to the inlet of the raw material buffer tank.

3. The system for producing battery-grade lithium carbonate by hydrogenation decomposition method according to claim 1, characterized in that: The outlet of the raw material feeding pump is connected to the outlet of the first-stage carbonization circulation pump through a raw material buffer outlet pipe. The outlet circulation pipe of the first-stage carbonization circulation pump is connected to the bottom inlet of the tube side of the first-stage carbonization cooler. The upper outlet of the tube side of the first-stage carbonization cooler is connected to the reaction liquid inlet of the first-stage carbonization bubbling tower. The reaction liquid outlet at the bottom of the first-stage carbonization bubbling tower is connected to the inlet of the first-stage carbonization circulation pump through a first-stage carbonization circulation pipe.

4. The system for producing battery-grade lithium carbonate by hydrogenation decomposition method according to claim 3, characterized in that: The first-stage carbonization circulation pipe is also connected to the outlet of the second-stage carbonization circulation pump through a carbonization transfer pipe. The outlet circulation pipe of the second-stage carbonization circulation pump is connected to the bottom inlet of the tube side of the second-stage carbonization cooler. The upper outlet of the tube side of the second-stage carbonization cooler is connected to the reaction liquid inlet of the second-stage carbonization bubbling tower. The reaction liquid outlet at the bottom of the second-stage carbonization bubbling tower is connected to the inlet of the second-stage carbonization circulation pump through a second-stage carbonization circulation pipe.

5. The system for producing battery-grade lithium carbonate by hydrogenation decomposition method according to claim 4, wherein: The circulating water inlet pipe is connected to the inlet of the shell side of the second-stage carbonization cooler. The outlet of the shell side of the second-stage carbonization cooler is connected to the inlet of the shell side of the first-stage carbonization cooler through a circulating water transfer pipe. The outlet of the shell side of the first-stage carbonization cooler is connected to the circulating water return pipe.

6. The system for producing battery-grade lithium carbonate by hydrogenation decomposition method according to claim 4, characterized in that: The first-stage carbonization circulation pipe and the second-stage carbonization circulation pipe are respectively connected to the inlet of the carbonization discharging pump through a lithium bicarbonate discharge pipe. The outlet of the carbonization discharging pump is connected to the inlet of the plate and frame filter press. The filtrate outlet of the plate and frame filter press is connected to the inlet of the first-stage filtrate tank. The outlet of the first-stage filtrate tank is connected to the inlet of the precision filter through a first-stage filtration pump. The filtrate outlet of the precision filter is connected to the inlet of the second-stage filtrate tank. The outlet of the second-stage filtrate tank is connected to the inlet of the cation exchange resin tank through a second-stage filtration pump and a second-stage filtrate conveying pipe. A pipeline iron remover is provided in the middle of the second-stage filtrate conveying pipe. The outlet of the cation exchange resin tank is connected to the inlet of the third-stage filtrate tank.

7. The system for producing battery-grade lithium carbonate by hydrogenation decomposition method according to claim 6, wherein: The outlet of the third-stage filtrate tank is connected to the cold side inlet of the condensate preheater through a third-stage clear liquid pump. The cold side outlet of the condensate preheater is connected to the circulation pipe of the pyrolysis crystallizer. The pyrolysis crystallizer includes two units connected in parallel. The shell-side steam inlets of the two pyrolysis crystallizers are respectively connected to the heating steam pipes, and the shell-side condensate outlets of the two pyrolysis heaters are respectively connected to the condensate tank. The outlet of the condensate tank is connected to the hot-side inlet of the condensate preheater through a condensate external transfer pump, and the hot-side outlet of the condensate preheater is connected to the condensate collection pipe.

8. The system for producing battery-grade lithium carbonate by hydrogenation decomposition method according to claim 7, characterized in that: The mother liquor outlets of the pyrolysis thickening tank and the centrifuge are both connected to the centrifugal mother liquor tank, and the bottom outlet of the centrifugal mother liquor tank is connected to the raw material buffer tank; The overflow outlet of the centrifugal mother liquor tank is connected to the inlet of the centrifugal clear liquid tank. The outlet of the centrifugal clear liquid tank is connected to the hot-side inlet of the discharge preheater through a centrifugal clear liquid pump and a clean mother liquor discharge pipe. The hot-side outlet of the discharge preheater is connected to the mother liquor inlet of the proportioning and metering tank through a clean mother liquor pipe. The cold-side outlet of the condensate preheater is connected to the cold-side inlet of the discharge preheater, and the cold-side outlet of the discharge preheater is connected to the circulation pipe of the pyrolysis crystallizer.

9. The system for producing battery-grade lithium carbonate by hydrogenation decomposition method according to claim 8, wherein: The cold-side outlet of the discharge preheater is connected to the inlet pipeline of the first pyrolysis heater circulation pump. The outlet of the first pyrolysis heater circulation pump is connected to the lower-end inlet of the tube side of the first pyrolysis heater. The upper-end outlet of the tube side of the first pyrolysis heater is connected to the feed liquid inlet of the first pyrolysis crystallizer. The feed liquid outlet of the first pyrolysis crystallizer is connected to the inlet of the first pyrolysis heater circulation pump through the first pyrolysis heater circulation pipe; The cold-side outlet of the discharge preheater is also connected to the inlet pipeline of the second pyrolysis heater circulation pump. The outlet of the second pyrolysis heater circulation pump is connected to the lower-end inlet of the tube side of the second pyrolysis heater. The upper-end outlet of the tube side of the second pyrolysis heater is connected to the feed liquid inlet of the second pyrolysis crystallizer. The feed liquid outlet of the second pyrolysis crystallizer is connected to the inlet of the second pyrolysis heater circulation pump through the second pyrolysis heater circulation pipe.

10. The system for producing battery-grade lithium carbonate by hydrogenation decomposition method according to claim 1, wherein: The tops of all storage tank equipment are connected to the tail gas main pipe. The outlet of the tail gas main pipe is connected to the inlet of the tail gas scrubbing tower through a draft fan. The scrubbing mother liquor outlet of the tail gas scrubbing tower is connected to the raw material buffer tank; the water replenishment port of the tail gas scrubbing tower is connected to the circulating water return pipe.

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