Preparation system and preparation method of battery-grade lithium carbonate

Abstract

The invention relates to the technical field of preparation processes of battery-grade lithium carbonate, and discloses a preparation system of battery-grade lithium carbonate and a preparation method of the battery-grade lithium carbonate. Comprising a pulping tank, a homogenizing pump, a first reactor, a carbonization buffer tank, a first circulating pump, a filter, an ion exchange device, a delivery pump, a second reactor, a slurry buffer tank, a second circulating pump and post-treatment equipment which are sequentially connected through a main pipeline, the first proportioning valve is connected with the pulping tank through a first return pipeline, a second proportioning valve is arranged between the first circulating pump and the filter, the second proportioning valve is connected with the first reactor through a second return pipeline, and a third proportioning valve is arranged between the second circulating pump and the post-treatment equipment; and the third proportioning valve is connected with the second reactor through a third reflux pipeline. The preparation process is simplified, the use cost is reduced, and the preparation efficiency is improved.

Description

Technical Field

[0001] This application relates to the field of battery-grade lithium carbonate preparation technology, specifically to a preparation system and method for battery-grade lithium carbonate. Background Technology

[0002] Lithium carbonate is an important lithium salt in lithium compounds and a crucial raw material for the preparation of other lithium compounds and lithium alloys. It is widely used in industries such as electronics, optical materials, ceramics, and pharmaceuticals. In recent years, with the rapid development of new energy technologies, especially the lithium battery industry, the demand for high-quality lithium carbonate has been increasing daily.

[0003] Currently, the main lithium carbonate purification processes include carbonation, electrolysis, extraction, ion exchange, and adsorption. Among them, carbonation has gradually become the mainstream process for lithium carbonate production due to its high reaction efficiency, simple process, strong operability, low cost, and low pollution.

[0004] However, existing battery-grade lithium carbonate production processes involve multiple purification reactions and uneven distribution of lithium carbonate particle size before the reaction, resulting in a large number of production equipment, long production cycles, and low product quality. Summary of the Invention

[0005] This application provides a system and method for preparing battery-grade lithium carbonate, which solves the problems of existing battery-grade lithium carbonate production processes, such as a large number of production equipment, long production cycle, and low product quality.

[0006] In a first aspect, this application provides a system for preparing battery-grade lithium carbonate, comprising a slurry tank, a homogenizing pump, a first reactor, a carbonization buffer tank, a first circulation pump, a filter, an ion exchange device, a transfer pump, a second reactor, a slurry buffer tank, a second circulation pump, and a post-processing device connected sequentially via a main pipeline. A first proportional regulating valve is provided on the pipeline between the homogenizing pump and the first reactor, and the first proportional regulating valve is connected to the slurry tank via a first reflux pipeline. A second proportional regulating valve is provided on the pipeline between the first circulation pump and the filter, and the second proportional regulating valve is connected to the first reactor via a second reflux pipeline. A third proportional regulating valve is provided on the pipeline between the second circulation pump and the post-processing device, and the third proportional regulating valve is connected to the second reactor via a third reflux pipeline.

[0007] In one optional embodiment, a first buffer tank is provided on the pipeline between the second proportional regulating valve and the filter, and a second buffer tank is provided on the pipeline between the ion exchange device and the delivery pump.

[0008] In one alternative embodiment, a heat exchanger is also provided on the third return pipeline, and a preheater is provided on the pipeline between the delivery pump and the second reactor.

[0009] In one optional embodiment, the post-processing equipment includes a centrifuge and a disc dryer, and the second circulating pump is sequentially connected to the centrifuge and the disc dryer via the main pipeline.

[0010] Secondly, this application also provides a method for preparing battery-grade lithium carbonate, using the above-mentioned battery-grade lithium carbonate preparation system, comprising:

[0011] Industrial-grade lithium carbonate and water are mixed into a slurry according to a first preset ratio and then fed into a mixing tank for preliminary premixing.

[0012] The premixed slurry is circulated between the pulping tank and the homogenizing pump for a preset time.

[0013] The slurry after circulation is returned to the pulping tank and fed into the first reactor according to a second preset ratio;

[0014] When the slurry input into the first reactor meets the first preset conditions in terms of reaction temperature, reaction pressure, and reaction residence time, a carbonization reaction is carried out to generate a reaction liquid.

[0015] The reaction solution is fed into a carbonization buffer tank to obtain a lithium bicarbonate solution;

[0016] The lithium bicarbonate solution is refluxed back into the first reactor and filtered through the input filter according to a third preset ratio.

[0017] The filtered lithium bicarbonate solution is fed into an ion exchange device to adsorb calcium and magnesium ions in the lithium bicarbonate solution.

[0018] The adsorbed lithium bicarbonate solution is fed into the second reactor, and when the reaction temperature, reaction pressure and reaction residence time meet the second preset conditions, a pyrolysis reaction is carried out to generate a pyrolysis slurry.

[0019] The pyrolysis slurry is fed into a slurry buffer tank to obtain lithium carbonate slurry;

[0020] The lithium carbonate slurry is refluxed into the second reactor according to a fourth preset ratio and then fed into a post-processing device for filtration, washing, and drying to obtain battery-grade lithium carbonate.

[0021] In one optional embodiment, the step of preparing industrial-grade lithium carbonate and water into a slurry according to a first preset ratio and inputting it into a mixing tank for preliminary premixing includes:

[0022] Industrial-grade lithium carbonate and water are mixed into a slurry at a solid-liquid weight ratio of 1:20 to 1:30 and then fed into a mixing tank for initial premixing.

[0023] In one optional embodiment, the step of recirculating the slurry back to the pulping tank and inputting it into the first reactor according to a second preset ratio includes:

[0024] The slurry after circulation is returned to the pulping tank at a reflux ratio of 50% to 90%, and the remaining slurry is fed into the first reactor. The reflux ratio is determined based on the degree of mixing of the homogenizing pump with the water and lithium carbonate.

[0025] In one optional embodiment, the step of refluxing the lithium bicarbonate solution into the first reactor at a third preset ratio and filtering it through the input filter includes:

[0026] The lithium bicarbonate solution is refluxed into the first reactor and filtered through an input filter at a third preset ratio of 10:1 to 80:1, wherein the third preset ratio is determined based on the reaction residence time of the first reactor.

[0027] In one optional embodiment, the step of refluxing the lithium carbonate slurry into the second reactor at a fourth preset ratio and then inputting it into a post-processing device for filtration, washing, and drying to obtain battery-grade lithium carbonate includes:

[0028] The lithium carbonate slurry is refluxed into the second reactor at a fourth preset ratio of 5:1 to 20:1 and then fed into a post-processing device for filtration, washing, and drying to obtain battery-grade lithium carbonate. The fourth preset ratio is determined based on the reaction residence time of the second reactor.

[0029] In one optional embodiment, the slurry input into the first reactor undergoes a carbonization reaction to generate a reaction liquid when the reaction temperature, reaction pressure, and reaction residence time meet a first preset condition, including:

[0030] The slurry input into the first reactor undergoes a carbonization reaction under the conditions of a reaction temperature of 15°C to 40°C, a reaction pressure of 0.1 MPa to 0.5 MPa, and a reaction residence time of 10 min to 60 min to generate a reaction liquid.

[0031] And / or, the step of feeding the adsorbed lithium bicarbonate solution into the second reactor, and when the reaction temperature, reaction pressure, and reaction residence time meet the second preset conditions, carrying out a pyrolysis reaction to generate a pyrolysis slurry, includes:

[0032] The adsorbed lithium bicarbonate solution is fed into the second reactor, where it undergoes a pyrolysis reaction at a reaction temperature of 60°C to 100°C, a reaction pressure of 0 MPa to 0.05 MPa, and a reaction residence time of 30 min to 60 min to generate a pyrolysis slurry.

[0033] The technical solution of this application has the following advantages:

[0034] 1. After preparing the lithium carbonate slurry in advance, it is first premixed in the slurry tank, and then fed into the first reactor by the homogenizing pump. The high shear force and high speed of the homogenizing pump are used to disperse, grind and emulsify the slurry. At the same time, the reflux ratio of the first reflux pipeline is adjusted by the first proportional regulating valve so that part of the slurry is returned to the slurry tank. This ensures that the particle size distribution of the slurry delivered to the first reactor by the homogenizing pump is narrow, thereby improving the slurry particle size distribution and improving the uniformity of lithium carbonate particle size distribution.

[0035] 2. Through the second proportional regulating valve and the second reflux pipeline, most of the lithium bicarbonate solution output from the carbonization buffer tank is returned to the first reactor. By setting up the carbonization buffer tank, the residence time of the carbonization reaction can be ensured, the carbonization reaction can be fully carried out, the carbonization reaction process can be simplified, continuous production can be achieved, and the production efficiency of battery-grade lithium carbonate can be improved.

[0036] 3. Through the third proportional regulating valve and the third reflux pipeline, most of the lithium carbonate slurry output from the slurry buffer tank can be recirculated back to the second reactor, simplifying the pyrolysis reaction process, shortening the pyrolysis reaction cycle, further improving the production efficiency of battery-grade lithium carbonate, and ultimately improving the product quality of battery-grade lithium carbonate. The slurry buffer tank ensures sufficient pyrolysis time.

[0037] 4. This application can shorten the carbonization time, thereby reducing the time required to pass carbon dioxide into the pyrolysis equipment for cleaning, and thus further improving production efficiency.

[0038] 5. The pyrolysis mother liquor and the generated carbon dioxide can be recycled and reused. The pyrolysis mother liquor in the pyrolysis process can also be used to preheat the carbonized liquid after fine filtration, so as to improve resource utilization and reduce usage costs. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0040] Figure 1This is a schematic diagram of the structure of the battery-grade lithium carbonate preparation system according to an embodiment of this application;

[0041] Figure 2 This is a flowchart illustrating the preparation method of battery-grade lithium carbonate according to an embodiment of this application.

[0042] Explanation of reference numerals in the attached figures:

[0043] 1. Pulping tank; 2. Homogenizing pump; 3. First reactor; 4. Carbonization buffer tank; 5. First circulation pump; 6. Filter; 7. Ion exchange device; 8. Transfer pump; 9. Second reactor; 10. Pulp buffer tank; 11. Second circulation pump; 12. Post-treatment equipment; 1201. Centrifuge; 1202. Tray dryer; 13. First proportional control valve; 14. First reflux pipeline; 15. Second proportional control valve; 16. Second reflux pipeline; 17. Third proportional control valve; 18. Third reflux pipeline; 19. Heat exchanger; 20. First buffer tank; 21. Second buffer tank; 22. Preheater; 23. First sub-pipeline; 24. Second sub-pipeline; 25. Third sub-pipeline; 26. Fourth sub-pipeline. Detailed Implementation

[0044] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0046] In the description of the embodiments in this application, "a plurality of" means two or more, unless otherwise expressly specified. The reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0047] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0048] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0049] In the description of the embodiments of this application, the technical terms "length", "width", "thickness", "upper", "lower", "inner", "outer", "axial", "radial", "circumferential", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0050] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0051] To address the problems existing in the aforementioned related technologies, according to the first aspect of this application, as follows: Figure 1 As shown, a battery-grade lithium carbonate preparation system is provided, including a slurry tank 1, a homogenizing pump 2, a first reactor 3, a carbonization buffer tank 4, a first circulation pump 5, a filter 6, an ion exchange device 7, a transfer pump 8, a second reactor 9, a slurry buffer tank 10, a second circulation pump 11, and a post-processing device 12, which are connected in sequence through a main pipeline.

[0052] Specifically, the outlet of the pulping tank 1 is connected to the inlet of the homogenizing pump 2 via the first sub-pipeline 23. The outlet of the homogenizing pump 2 is connected to the inlet of the first reactor 3 via the second sub-pipeline 24. The first circulation pump 5 is connected to the filter 6 via the third sub-pipeline 25. The second circulation pump 11 is connected to the post-treatment equipment 12 via the fourth sub-pipeline 26. The first reactor 3 is connected to an air inlet pipe for conveying carbon dioxide.

[0053] Specifically, a first proportional regulating valve 13 is installed on the second sub-pipeline 24 between the homogenizing pump 2 and the first reactor 3. The first proportional regulating valve 13 is connected to the inlet of the pulping tank 1 through the first reflux pipeline 14. A second proportional regulating valve 15 is installed on the third sub-pipeline 25 between the first circulating pump 5 and the filter 6. The second proportional regulating valve 15 is connected to the inlet of the first reactor 3 through the second reflux pipeline 16. A third proportional regulating valve 17 is installed on the fourth sub-pipeline 26 between the second circulating pump 11 and the post-treatment equipment 12. The third proportional regulating valve 17 is connected to the second reactor 9 through the third reflux pipeline 18.

[0054] The battery-grade lithium carbonate preparation system provided in this application embodiment pre-prepares a lithium carbonate slurry, which is then pre-mixed in a slurry tank 1 before being fed into a first reactor 3 via a homogenizing pump 2. The high shear force and high rotation speed of the homogenizing pump 2 are used to disperse, grind, and emulsify the slurry. Simultaneously, the reflux ratio of the first reflux pipeline 14 is adjusted by a first proportional regulating valve 13, allowing a portion of the slurry to flow back into the slurry tank 1. This ensures that the slurry particles delivered to the first reactor 3 by the homogenizing pump 2 have a narrow particle size distribution, thereby improving the slurry particle size distribution and enhancing the uniformity of lithium carbonate particle size distribution. Through a second proportional regulating valve 15 and a second reflux pipeline 16, most of the lithium bicarbonate solution output from the carbonation buffer tank 4 is refluxed back into the first reactor 3. By setting up the carbonation buffer tank 4, the residence time of the carbonation reaction is ensured, guaranteeing the full progress of the carbonation reaction, simplifying the carbonation process, enabling continuous production, and improving the production efficiency of battery-grade lithium carbonate. Through the third proportional regulating valve 17 and the third reflux pipeline 18, most of the lithium carbonate slurry output from the slurry buffer tank 10 can be recirculated back to the second reactor 9, simplifying the pyrolysis reaction process, shortening the pyrolysis reaction cycle, further improving the production efficiency of battery-grade lithium carbonate, and ultimately improving the product quality of battery-grade lithium carbonate. The slurry buffer tank 10 ensures sufficient pyrolysis time.

[0055] Furthermore, some pyrolysis equipment is prone to scaling. The embodiments of this application shorten the carbonization time, thereby reducing the time required to pass carbon dioxide through the pyrolysis equipment for cleaning, and further improving production efficiency.

[0056] Specifically, the ion exchange unit 7 is filled with lithium-type chelating ion exchange resin. The second reactor 9 contains pyrolysis mother liquor. The filter 6 can be a precision filter. The reflux ratio of the first reflux pipeline 14 can be controlled by the first proportional regulating valve 13, with a reflux ratio of 50% to 90%, that is, the slurry refluxed back to the pulping tank 1 accounts for 50% to 90% of the total volume, in order to improve the slurry particle size and facilitate the improvement of the uniformity of lithium carbonate particle size distribution. The reflux ratio of the second reflux pipeline 16 is controlled by the second proportional regulating valve 15, with the ratio of lithium bicarbonate solution refluxed back to the first reactor 3 to lithium bicarbonate solution input to the filter 6 being 10:1 to 80:1. The proportion of lithium bicarbonate solution refluxed to the first reactor 3 is relatively large, so as to achieve cyclic purification without the need to add other reactors, thus saving equipment usage. The reflux ratio of the third reflux pipeline 18 is controlled by the third proportional regulating valve 17, with the ratio of lithium carbonate slurry refluxed back to the second reactor 9 to lithium carbonate slurry input to the post-processing equipment 12 being 5:1 to 20:1. A large proportion of the lithium carbonate slurry is returned to the second reactor 9 in order to shorten the pyrolysis reaction cycle.

[0057] It should be noted that the embodiments of this application do not limit the structure of the first reactor 3 and the second reactor 9, and any existing structure can be selected as needed. For example, the first reactor 3 and the second reactor 9 are rotating packed beds.

[0058] Furthermore, the embodiments of this application do not limit the homogenizing pump 2, for example, the homogenizing pump 2 is a high-speed shear homogenizing pump.

[0059] In one alternative implementation, such as Figure 1 As shown, a first buffer tank 20 is installed on the pipeline between the second proportional regulating valve 15 and the filter 6. A second buffer tank 21 is installed on the pipeline between the ion exchange device 7 and the transfer pump 8. By setting up the first buffer tank 20, the lithium bicarbonate solution output from the third sub-pipeline 25 can be collected, ensuring that a sufficient amount of lithium bicarbonate solution enters the filter 6 for filtration, thereby ensuring the quality of lithium carbonate preparation. By setting up the second buffer tank 21, the lithium bicarbonate solution output from the ion exchange device 7 after adsorbing calcium and magnesium ions can be collected, ensuring that a sufficient amount of lithium bicarbonate solution enters the second reactor 9.

[0060] In one alternative implementation, such as Figure 1 As shown, a heat exchanger 19 is also installed on the third return pipeline 18, and a preheater 22 is installed on the pipeline between the transfer pump 8 and the second reactor 9. The preheater 22 is located at the inlet of the second reactor 9. The preheater 22 uses the high-temperature pyrolysis mother liquor to preheat the finely filtered carbonized liquid to reduce energy consumption and costs.

[0061] In one alternative implementation, such as Figure 1 As shown, the post-processing equipment 12 includes a centrifuge 1201 and a disc dryer 1202. The outlet of the second circulation pump 10 is connected to the inlet of the centrifuge 1201 via a main pipeline, and the outlet of the centrifuge 1201 is connected to the inlet of the disc dryer 1202 via a main pipeline. The outlet of the disc dryer 1202 outputs battery-grade lithium carbonate product.

[0062] Secondly, such as Figure 2 As shown, this application also provides a method for preparing battery-grade lithium carbonate, using the battery-grade lithium carbonate preparation system of this application, including:

[0063] S100. Industrial-grade lithium carbonate and water are mixed into a slurry according to a first preset ratio and input into the pulping tank 1 for preliminary premixing.

[0064] S200: The pre-mixed slurry is circulated between the mixing tank 1 and the homogenizing pump 2 for a preset time.

[0065] S300, the slurry after circulation is returned to the pulping tank 1 and fed into the first reactor 3 according to the second preset ratio.

[0066] S400: When the slurry input into the first reactor 3 meets the first preset conditions in terms of reaction temperature, reaction pressure and reaction residence time, a carbonization reaction is carried out to generate a reaction liquid.

[0067] S500, the reaction solution is fed into carbonization buffer tank 4 to obtain lithium bicarbonate solution.

[0068] S600, the lithium bicarbonate solution is refluxed back into the first reactor 3 and filtered through the input filter 6 according to the third preset ratio.

[0069] S700. The filtered lithium bicarbonate solution is fed into the ion exchange device 7 to adsorb calcium and magnesium ions in the lithium bicarbonate solution.

[0070] S800, The adsorbed lithium bicarbonate solution is fed into the second reactor 9. When the reaction temperature, reaction pressure and reaction residence time meet the second preset conditions, a pyrolysis reaction is carried out to generate a pyrolysis slurry.

[0071] S900, the pyrolysis slurry is fed into the slurry buffer tank 10 to obtain lithium carbonate slurry.

[0072] S1000, the lithium carbonate slurry is refluxed into the second reactor 9 according to the fourth preset ratio and fed into the post-processing equipment 12 for filtration, washing and drying to obtain battery-grade lithium carbonate.

[0073] The method for preparing battery-grade lithium carbonate provided in this application involves pre-preparing a lithium carbonate slurry, initially pre-mixing it in a slurry tank 1, then circulating it through a homogenizing pump 2 until stable before inputting it into a first reactor 3. The high shear force and high rotation speed of the homogenizing pump 2 are used to disperse, grind, and emulsify the slurry. Simultaneously, according to a second preset ratio, a portion of the slurry is returned to the slurry tank 1 to ensure a narrow particle size distribution in the slurry delivered to the first reactor 3 by the homogenizing pump 2, thereby improving the slurry particle size distribution and enhancing the uniformity of lithium carbonate particle size distribution. According to a third preset ratio, most of the lithium bicarbonate solution output from the carbonation buffer tank 4 can be returned to the first reactor 3. By setting up the carbonation buffer tank 4, the residence time of the carbonation reaction can be ensured, guaranteeing the full progress of the carbonation reaction, simplifying the carbonation process, enabling continuous production, and improving the production efficiency of battery-grade lithium carbonate. According to the fourth preset ratio, most of the lithium carbonate slurry output from the slurry buffer tank 10 can be recycled back to the second reactor 9, simplifying the pyrolysis reaction process, shortening the pyrolysis reaction cycle, further improving the production efficiency of battery-grade lithium carbonate, and ultimately improving the product quality of battery-grade lithium carbonate. By setting up the slurry buffer tank 10, the pyrolysis time can be ensured.

[0074] Furthermore, the pyrolysis mother liquor and the carbon dioxide generated by the pyrolysis reaction can be repeatedly fed into the first reactor 3 and recycled. The pyrolysis mother liquor can also preheat the carbonized liquid after fine filtration to improve resource utilization. The pyrolysis mother liquor can also regenerate the resin in the ion exchange device 7, and the regenerated resin can be reused to reduce operating costs.

[0075] Specifically, in S700, the calcium ion concentration in the lithium bicarbonate solution after ion exchange is ≤1 mg / L, and the magnesium ion concentration is ≤1 mg / L. Ensuring the calcium and magnesium ion content in the solution guarantees the quality of the lithium carbonate product.

[0076] In an optional embodiment, S100, industrial-grade lithium carbonate and water are mixed into a slurry according to a first preset ratio and input into the pulping tank 1 for preliminary premixing, including:

[0077] S110. Industrial-grade lithium carbonate and water are mixed into a slurry at a solid-liquid weight ratio of 1:20 to 1:30 and then fed into the mixing tank 1 for preliminary premixing.

[0078] In an optional embodiment, step S300, returning the slurry after circulation to the pulping tank 1 and inputting it into the first reactor 3 according to a second preset ratio, includes:

[0079] S310. The slurry after circulation is returned to the mixing tank 1 and fed into the first reactor 3 at a return ratio of 50% to 90%. The return ratio is determined based on the degree of mixing of water and lithium carbonate by the homogenizing pump 2. The maximum particle size of the slurry output by the homogenizing pump 2 is less than 4 μm to improve the particle size of the slurry entering the first reactor 3.

[0080] In an optional embodiment, S600, the process of refluxing the lithium bicarbonate solution into the first reactor 3 according to a third preset ratio and filtering it through the input filter 6, includes:

[0081] S610. The lithium bicarbonate solution is refluxed into the first reactor 3 and filtered through the input filter 6 at a third preset ratio of 10:1 to 80:1. The third preset ratio is determined based on the reaction residence time of the first reactor 3. The lithium bicarbonate solution filtered through the filter 6 has an SS ≤ 5 mg / L.

[0082] In an optional embodiment, S1000, the lithium carbonate slurry is refluxed into the second reactor 9 according to a fourth preset ratio and then fed into the post-processing equipment 12 for filtration, washing, and drying to obtain battery-grade lithium carbonate, including:

[0083] S1010. The lithium carbonate slurry is refluxed into the second reactor 9 and fed into the post-processing equipment 12 for filtration, washing and drying to obtain battery-grade lithium carbonate. The fourth preset ratio is determined based on the reaction residence time of the second reactor 9.

[0084] In an optional embodiment, in step S400, when the slurry input into the first reactor 3 meets the first preset conditions in terms of reaction temperature, reaction pressure, and reaction residence time, a carbonization reaction is carried out to generate a reaction liquid, including:

[0085] S410. The slurry input into the first reactor 3 undergoes a carbonization reaction under the conditions of a reaction temperature of 15℃ to 40℃, a reaction pressure of 0.1MPa to 0.5MPa, and a reaction residence time of 10min to 60min to generate a reaction liquid.

[0086] Furthermore, the endpoint of the carbonization reaction is determined by pH. The endpoint can be determined when the pH is between 7 and 8. The measurement method is simple and convenient to use.

[0087] In an optional embodiment, in step S800, the adsorbed lithium bicarbonate solution is input into the second reactor 9. When the reaction temperature, reaction pressure, and reaction residence time meet the second preset conditions, a pyrolysis reaction is carried out to generate a pyrolysis slurry, including:

[0088] S810. The adsorbed lithium bicarbonate solution is fed into the second reactor 9. A pyrolysis reaction is carried out under the conditions of a reaction temperature of 60℃ to 100℃, a reaction pressure of 0MPa to 0.05MPa, and a reaction residence time of 30min to 60min to generate a pyrolysis slurry. Since this process is a pyrolysis reaction, heating the lithium bicarbonate solution to pyrolyze it into a lithium carbonate slurry requires increasing the reaction temperature. Carbon dioxide is released during pyrolysis, increasing the gas pressure; therefore, the reaction pressure needs to be reduced, requiring only a slight positive pressure.

[0089] The following detailed description of the preparation method of battery-grade lithium carbonate in this application is provided with specific examples. These examples should not be construed as limiting the scope of protection claimed in this application.

[0090] Example 1:

[0091] Industrial-grade lithium carbonate and water were mixed at a solid-liquid weight ratio of 1:25 to form a slurry, which was then fed into mixing tank 1 for preliminary premixing. The premixed slurry was circulated between mixing tank 1 and homogenizing pump 2 for 30 minutes at a circulation flow rate of 10 m³ / s. 3 / h. After that, the slurry after circulation is returned to the pulping tank 1 and fed into the first reactor 3 at a reflux ratio of 60%.

[0092] Carbon dioxide gas is introduced into the first reactor 3, and the flow rate is adjusted to 180 Nm³. 3 The reaction is carried out at a rate of 1 h, a reaction temperature of 20°C, and a pressure of 0.3 MPa maintained inside the first reactor 3 and the carbonization buffer tank 4. The reaction residence time is controlled at 30 min to carry out the carbonization reaction and generate a reaction solution. The reaction solution is then fed into the carbonization buffer tank 4 to obtain a lithium bicarbonate solution.

[0093] The ratio of lithium bicarbonate solution refluxed to the first reactor 3 to the input filter 6 is controlled at 14:1, and the reflux flow rate is 140 m³ / s. 3 / h. The lithium bicarbonate solution is filtered using filter 6. The lithium bicarbonate solution entering filter 6 is first collected through the first buffer tank 20, with the flow rate controlled at 10m³ / h. 3 / h.

[0094] The filtered lithium bicarbonate solution is fed into the ion exchange device 7 to adsorb calcium and magnesium ions in the lithium bicarbonate solution, and the resulting ion exchange solution is fed into the second buffer tank 21.

[0095] The ion exchange solution in the second buffer tank 21 is preheated by the preheater 22 and then fed into the second reactor 9 at a preheating temperature of 50°C. The flow rate of the second reactor 9 is controlled to be 10 m³ / s. 3 The reaction was carried out at a rate of 90℃ / h, a reaction temperature of 90℃, a reaction pressure of 0.02MPa, and a reaction residence time of 60min, to generate a pyrolysis slurry. The pyrolysis slurry was then fed into a slurry buffer tank 10 to obtain a lithium carbonate slurry.

[0096] The ratio of lithium carbonate slurry refluxed to the second reactor 9 to that input to the post-treatment equipment 12 is controlled at 14:1, and the reflux flow rate is adjusted to 140 m³ / s. 3 / h.

[0097] After filtration, washing, and drying by post-processing equipment 12, battery-grade lithium carbonate product S1 is obtained.

[0098] Example 2:

[0099] Industrial-grade lithium carbonate and water were mixed at a solid-liquid weight ratio of 1:20 to form a slurry, which was then fed into mixing tank 1 for preliminary premixing. The premixed slurry was circulated between mixing tank 1 and homogenizing pump 2 for 30 minutes at a circulation flow rate of 10 m³ / min. 3 / h. After that, the slurry after circulation is returned to the pulping tank 1 and fed into the first reactor 3 at a reflux ratio of 60%.

[0100] Carbon dioxide gas is introduced into the first reactor 3, and the flow rate is adjusted to 180 Nm³. 3The reaction is carried out at a rate of 1 h, a reaction temperature of 20°C, and a pressure of 0.3 MPa maintained inside the first reactor 3 and the carbonization buffer tank 4. The reaction residence time is controlled at 30 min to carry out the carbonization reaction and generate a reaction solution. The reaction solution is then fed into the carbonization buffer tank 4 to obtain a lithium bicarbonate solution.

[0101] The ratio of lithium bicarbonate solution refluxed to the first reactor 3 to the input filter 6 is controlled at 28:1, and the reflux flow rate is 280 m³ / s. 3 / h. The lithium bicarbonate solution is filtered using filter 6. The lithium bicarbonate solution entering filter 6 is first collected through the first buffer tank 20, with the flow rate controlled at 10m³ / h. 3 / h.

[0102] The filtered lithium bicarbonate solution is fed into the ion exchange device 7 to adsorb calcium and magnesium ions in the lithium bicarbonate solution, and the resulting ion exchange solution is fed into the second buffer tank 21.

[0103] The ion exchange solution in the second buffer tank 21 is preheated by the preheater 22 and then fed into the second reactor 9 at a preheating temperature of 50°C. The flow rate of the second reactor 9 is controlled to be 10 m³ / s. 3 The reaction was carried out at a rate of 90℃ / h, a reaction temperature of 90℃, a reaction pressure of 0.02MPa, and a reaction residence time of 30min, to generate a pyrolysis slurry. The pyrolysis slurry was then fed into a slurry buffer tank 10 to obtain a lithium carbonate slurry.

[0104] The ratio of lithium carbonate slurry refluxed to the second reactor 9 to that input to the post-treatment equipment 12 is controlled at 14:1, and the reflux flow rate is adjusted to 140 m³ / s. 3 / h.

[0105] After filtration, washing, and drying by post-processing equipment 12, battery-grade lithium carbonate product S2 is obtained.

[0106] Example 3:

[0107] Industrial-grade lithium carbonate and water were mixed at a solid-liquid weight ratio of 1:20 to form a slurry, which was then fed into mixing tank 1 for preliminary premixing. The premixed slurry was circulated between mixing tank 1 and homogenizing pump 2 for 30 minutes at a circulation flow rate of 10 m³ / min. 3 / h. After that, the slurry after circulation is returned to the pulping tank 1 and fed into the first reactor 3 at a reflux ratio of 60%.

[0108] Carbon dioxide gas is introduced into the first reactor 3, and the flow rate is adjusted to 180 Nm³. 3 The reaction is carried out at a rate of 1 h, with a reaction temperature of 20°C. The pressure inside the first reactor 3 and the carbonization buffer tank 4 is maintained at 0.3 MPa, and the reaction residence time is controlled at 15 min to carry out the carbonization reaction and generate a reaction solution. The reaction solution is then fed into the carbonization buffer tank 4 to obtain a lithium bicarbonate solution.

[0109] The ratio of lithium bicarbonate solution refluxed to the first reactor 3 to the input filter 6 is controlled at 28:1, and the reflux flow rate is 280 m³ / s. 3 / h. The lithium bicarbonate solution is filtered using filter 6. The lithium bicarbonate solution entering filter 6 is first collected through the first buffer tank 20, with the flow rate controlled at 10m³ / h. 3 / h.

[0110] The filtered lithium bicarbonate solution is fed into the ion exchange device 7 to adsorb calcium and magnesium ions in the lithium bicarbonate solution, and the resulting ion exchange solution is fed into the second buffer tank 21.

[0111] The ion exchange solution in the second buffer tank 21 is preheated by the preheater 22 and then fed into the second reactor 9 at a preheating temperature of 50°C. The flow rate of the second reactor 9 is controlled to be 10 m³ / s. 3 The reaction was carried out at a rate of 90℃ / h, a reaction temperature of 90℃, a reaction pressure of 0.02MPa, and a reaction residence time of 30min, to generate a pyrolysis slurry. The pyrolysis slurry was then fed into a slurry buffer tank 10 to obtain a lithium carbonate slurry.

[0112] The ratio of lithium carbonate slurry refluxed to the second reactor 9 to that input to the post-treatment equipment 12 is controlled at 14:1, and the reflux flow rate is adjusted to 140 m³ / s. 3 / h.

[0113] After filtration, washing, and drying by post-processing equipment 12, battery-grade lithium carbonate product S3 is obtained.

[0114] Example 4:

[0115] Industrial-grade lithium carbonate and water were mixed at a solid-liquid weight ratio of 1:20 to form a slurry, which was then fed into mixing tank 1 for preliminary premixing. The premixed slurry was circulated between mixing tank 1 and homogenizing pump 2 for 30 minutes at a circulation flow rate of 10 m³ / min. 3 / h. After that, the slurry after circulation is returned to the pulping tank 1 and fed into the first reactor 3 at a reflux ratio of 60%.

[0116] Carbon dioxide gas is introduced into the first reactor 3, and the flow rate is adjusted to 180 Nm³. 3 The reaction is carried out at a rate of 1 h, a reaction temperature of 20°C, and a pressure of 0.3 MPa maintained inside the first reactor 3 and the carbonization buffer tank 4. The reaction residence time is controlled at 5 min to carry out the carbonization reaction and generate a reaction solution. The reaction solution is then fed into the carbonization buffer tank 4 to obtain a lithium bicarbonate solution.

[0117] The ratio of lithium bicarbonate solution refluxed to the first reactor 3 to the input filter 6 is controlled at 14:1, and the reflux flow rate is 140 m³ / s. 3 / h. The lithium bicarbonate solution is filtered using filter 6. The lithium bicarbonate solution entering filter 6 is first collected through the first buffer tank 20, with the flow rate controlled at 10m³ / h. 3 / h.

[0118] The filtered lithium bicarbonate solution is fed into the ion exchange device 7 to adsorb calcium and magnesium ions in the lithium bicarbonate solution, and the resulting ion exchange solution is fed into the second buffer tank 21.

[0119] The ion exchange solution in the second buffer tank 21 is preheated by the preheater 22 and then fed into the second reactor 9 at a preheating temperature of 50°C. The flow rate of the second reactor 9 is controlled to be 10 m³ / s. 3 The reaction was carried out at a rate of 90℃ / h, a reaction temperature of 90℃, a reaction pressure of 0.02MPa, and a reaction residence time of 30min, to generate a pyrolysis slurry. The pyrolysis slurry was then fed into a slurry buffer tank 10 to obtain a lithium carbonate slurry.

[0120] The ratio of lithium carbonate slurry refluxed to the second reactor 9 to that input to the post-treatment equipment 12 is controlled at 14:1, and the reflux flow rate is adjusted to 140 m³ / s. 3 / h.

[0121] After filtration, washing, and drying by post-processing equipment 12, battery-grade lithium carbonate product S4 is obtained.

[0122] Example 5:

[0123] Industrial-grade lithium carbonate and water were mixed at a solid-liquid weight ratio of 1:20 to form a slurry, which was then fed into mixing tank 1 for preliminary premixing. The premixed slurry was circulated between mixing tank 1 and homogenizing pump 2 for 30 minutes at a circulation flow rate of 10 m³ / min. 3 / h. After that, the slurry after circulation is returned to the pulping tank 1 and fed into the first reactor 3 at a reflux ratio of 50%.

[0124] Carbon dioxide gas is introduced into the first reactor 3, and the flow rate is adjusted to 180 Nm³. 3 The reaction is carried out at a rate of 1 h, with a reaction temperature of 20°C. The pressure inside the first reactor 3 and the carbonization buffer tank 4 is maintained at 0.3 MPa, and the reaction residence time is controlled at 15 min to carry out the carbonization reaction and generate a reaction solution. The reaction solution is then fed into the carbonization buffer tank 4 to obtain a lithium bicarbonate solution.

[0125] The ratio of lithium bicarbonate solution refluxed to the first reactor 3 to the input filter 6 is controlled at 28:1, and the reflux flow rate is 280 m³ / s. 3 / h. The lithium bicarbonate solution is filtered using filter 6. The lithium bicarbonate solution entering filter 6 is first collected through the first buffer tank 20, with the flow rate controlled at 10m³ / h. 3 / h.

[0126] The filtered lithium bicarbonate solution is fed into the ion exchange device 7 to adsorb calcium and magnesium ions in the lithium bicarbonate solution, and the resulting ion exchange solution is fed into the second buffer tank 21.

[0127] The ion exchange solution in the second buffer tank 21 is preheated by the preheater 22 and then fed into the second reactor 9 at a preheating temperature of 50°C. The flow rate of the second reactor 9 is controlled to be 10 m³ / s. 3 The reaction was carried out at a rate of 90℃ / h, a reaction temperature of 90℃, a reaction pressure of 0.02MPa, and a reaction residence time of 30min, to generate a pyrolysis slurry. The pyrolysis slurry was then fed into a slurry buffer tank 10 to obtain a lithium carbonate slurry.

[0128] The ratio of lithium carbonate slurry refluxed to the second reactor 9 to that input to the post-treatment equipment 12 is controlled at 14:1, and the reflux flow rate is adjusted to 140 m³ / s. 3 / h.

[0129] After filtration, washing, and drying by post-processing equipment 12, battery-grade lithium carbonate product S5 is obtained.

[0130] Example 6:

[0131] Industrial-grade lithium carbonate and water were mixed at a solid-liquid weight ratio of 1:20 to form a slurry, which was then fed into mixing tank 1 for preliminary premixing. The premixed slurry was circulated between mixing tank 1 and homogenizing pump 2 for 30 minutes at a circulation flow rate of 10 m³ / min. 3 / h. After that, the slurry after circulation is returned to the pulping tank 1 and fed into the first reactor 3 at a reflux ratio of 60%.

[0132] Carbon dioxide gas is introduced into the first reactor 3, and the flow rate is adjusted to 180 Nm³. 3 The reaction is carried out at a rate of 1 h, with a reaction temperature of 20°C. The pressure inside the first reactor 3 and the carbonization buffer tank 4 is maintained at 0.3 MPa, and the reaction residence time is controlled at 15 min to carry out the carbonization reaction and generate a reaction solution. The reaction solution is then fed into the carbonization buffer tank 4 to obtain a lithium bicarbonate solution.

[0133] The ratio of lithium bicarbonate solution refluxed to the first reactor 3 to the input filter 6 is controlled at 28:1, and the reflux flow rate is 280 m³ / s. 3 / h. The lithium bicarbonate solution is filtered using filter 6. The lithium bicarbonate solution entering filter 6 is first collected through the first buffer tank 20, with the flow rate controlled at 10m³ / h. 3 / h.

[0134] The filtered lithium bicarbonate solution is fed into the ion exchange device 7 to adsorb calcium and magnesium ions in the lithium bicarbonate solution, and the resulting ion exchange solution is fed into the second buffer tank 21.

[0135] The ion exchange solution in the second buffer tank 21 is preheated by the preheater 22 and then fed into the second reactor 9 at a preheating temperature of 50°C. The flow rate of the second reactor 9 is controlled to be 10 m³ / s. 3 The reaction was carried out at a rate of 60℃ / h, a reaction temperature of 60℃, a reaction pressure of 0.02MPa, and a reaction residence time of 30min, to generate a pyrolysis slurry. The pyrolysis slurry was then fed into a slurry buffer tank 10 to obtain a lithium carbonate slurry.

[0136] The ratio of lithium carbonate slurry refluxed to the second reactor 9 to that input to the post-treatment equipment 12 is controlled at 14:1, and the reflux flow rate is adjusted to 140 m³ / s. 3 / h.

[0137] After filtration, washing, and drying by post-processing equipment 12, battery-grade lithium carbonate product S6 is obtained.

[0138] The battery-grade lithium carbonate products obtained from the above examples were tested according to the industry standard for lithium carbonate, namely the People's Republic of China Nonferrous Metals Industry Standard—Battery-grade Lithium Carbonate (YS / T582-2013). The test results are shown in Table 1.

[0139] Table 1: Test Results

[0140]

[0141] As can be seen, the battery-grade lithium carbonate prepared by S1, S2, S3, S5, and S6 using the embodiments of this application all have a lithium carbonate content greater than 99.5%, which meets the quality standard for battery-grade lithium carbonate. S4, as a control example, does not meet the preparation conditions of the embodiments of this application and does not meet the quality standard for battery-grade lithium carbonate.

[0142] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this application.

Claims

1. A system for preparing battery-grade lithium carbonate, characterized in that, The system includes a pulping tank (1), a homogenizing pump (2), a first reactor (3), a carbonization buffer tank (4), a first circulation pump (5), a filter (6), an ion exchange device (7), a transfer pump (8), a second reactor (9), a slurry buffer tank (10), a second circulation pump (11), and a post-treatment device (12) connected sequentially via a main pipeline. A first proportional regulating valve (13) is provided on the pipeline between the homogenizing pump (2) and the first reactor (3), and the first proportional regulating valve (13) is connected to the pulping tank (1) via a first return pipeline (14). A second proportional regulating valve (15) is provided on the pipeline between the first circulation pump (5) and the filter (6), and the second proportional regulating valve (15) is connected to the first reactor (3) via a second return pipeline (16). A third proportional regulating valve (17) is provided on the pipeline between the second circulation pump (11) and the post-treatment device (12), and the third proportional regulating valve (17) is connected to the second reactor (9) via a third return pipeline (18).

2. The battery-grade lithium carbonate preparation system according to claim 1, characterized in that, A first buffer tank (20) is provided on the pipeline between the second proportional regulating valve (15) and the filter (6), and a second buffer tank (21) is provided on the pipeline between the ion exchange device (7) and the delivery pump (8).

3. The battery-grade lithium carbonate preparation system according to claim 2, characterized in that, A heat exchanger (19) is also provided on the third return pipeline (18), and a preheater (22) is provided on the pipeline between the delivery pump (8) and the second reactor (9).

4. The system for preparing battery-grade lithium carbonate according to any one of claims 1 to 3, characterized in that, The post-processing equipment (12) includes a centrifuge (1201) and a disc dryer (1202), and the second circulating pump (11) is connected in sequence to the centrifuge (1201) and the disc dryer (1202) through the main pipeline.

5. A method for preparing battery-grade lithium carbonate, characterized in that, The battery-grade lithium carbonate preparation system according to any one of claims 1 to 4 comprises: Industrial-grade lithium carbonate and water are mixed into a slurry according to a first preset ratio and then fed into a mixing tank (1) for preliminary premixing. The premixed slurry is circulated between the pulping tank (1) and the homogenizing pump (2) for a preset time. The slurry after circulation is returned to the pulping tank (1) and fed into the first reactor (3) according to the second preset ratio; When the slurry input into the first reactor (3) meets the first preset conditions in terms of reaction temperature, reaction pressure and reaction residence time, it undergoes a carbonization reaction to generate a reaction liquid; The reaction solution is fed into a carbonization buffer tank (4) to obtain a lithium bicarbonate solution; The lithium bicarbonate solution is refluxed back into the first reactor (3) and filtered through the input filter (6) according to a third preset ratio; The filtered lithium bicarbonate solution is fed into the ion exchange device (7) to adsorb calcium and magnesium ions in the lithium bicarbonate solution. The adsorbed lithium bicarbonate solution is fed into the second reactor (9). When the reaction temperature, reaction pressure and reaction residence time meet the second preset conditions, a pyrolysis reaction is carried out to generate a pyrolysis slurry. The pyrolysis slurry is fed into the slurry buffer tank (10) to obtain lithium carbonate slurry; The lithium carbonate slurry is refluxed into the second reactor (9) according to the fourth preset ratio and fed into the post-processing equipment (12) for filtration, washing and drying to obtain battery-grade lithium carbonate.

6. The method for preparing battery-grade lithium carbonate according to claim 5, characterized in that, The step of preparing industrial-grade lithium carbonate and water into a slurry according to a first preset ratio and inputting it into a mixing tank (1), and pre-mixing it in the mixing tank (1), includes: Industrial-grade lithium carbonate and water are mixed in a solid-liquid weight ratio of 1:20 to 1:30 to form a slurry, which is then fed into a mixing tank (1) for preliminary premixing.

7. The method for preparing battery-grade lithium carbonate according to claim 5, characterized in that, The step of returning the slurry after circulation to the pulping tank (1) and inputting it into the first reactor (3) according to a second preset ratio includes: The slurry after circulation is returned to the pulping tank (1) at a return ratio of 50% to 90%, and the remaining slurry is fed into the first reactor (3). The return ratio is determined based on the degree of mixing of water and lithium carbonate by the homogenizing pump (2).

8. The method for preparing battery-grade lithium carbonate according to claim 5, characterized in that, The lithium bicarbonate solution is refluxed back into the first reactor (3) and filtered through the input filter (6) according to a third preset ratio, including: The lithium bicarbonate solution is refluxed into the first reactor (3) and filtered through the input filter (6) at a third preset ratio of 10:1 to 80:1, the third preset ratio being determined based on the reaction residence time of the first reactor (3).

9. The method for preparing battery-grade lithium carbonate according to claim 5, characterized in that, The process of refluxing the lithium carbonate slurry into the second reactor (9) according to a fourth preset ratio and then inputting it into the post-processing equipment (12) for filtration, washing, and drying to obtain battery-grade lithium carbonate includes: The lithium carbonate slurry is refluxed into the second reactor (9) and fed into the post-processing equipment (12) at a fourth preset ratio of 5:1 to 20:1 to obtain battery-grade lithium carbonate. The fourth preset ratio is determined based on the reaction residence time of the second reactor (9).

10. The method for preparing battery-grade lithium carbonate according to claim 5, characterized in that, When the slurry input into the first reactor (3) meets the first preset conditions in terms of reaction temperature, reaction pressure, and reaction residence time, it undergoes a carbonization reaction to generate a reaction liquid, including: The slurry input into the first reactor (3) undergoes a carbonization reaction under the conditions of a reaction temperature of 15°C to 40°C, a reaction pressure of 0.1MPa to 0.5MPa, and a reaction residence time of 10min to 60min to generate a reaction liquid; And / or, the step of feeding the adsorbed lithium bicarbonate solution into the second reactor (9), and when the reaction temperature, reaction pressure, and reaction residence time meet the second preset conditions, carrying out a pyrolysis reaction to generate a pyrolysis slurry, includes: The adsorbed lithium bicarbonate solution is fed into the second reactor (9) and subjected to pyrolysis under the conditions of reaction temperature of 60°C to 100°C, reaction pressure of 0 MPa to 0.05 MPa and reaction residence time of 30 min to 60 min to generate pyrolysis slurry.

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