Carbonization and purification system for preparing lithium carbonate

Abstract

The utility model discloses a carbonization and purification system for preparing lithium carbonate. The carbonization and purification system comprises a pulping device, a gas-slurry shearing and mixing device, a carbonization device and a post-treatment device which are connected in sequence, the carbonization device comprises a carbonization reactor and a carbonization receiver which are connected in sequence, a feeding port is formed in the bottom of the carbonization reactor, an overflow port is formed in the top of the carbonization reactor, and the overflow port of the carbonization reactor is communicated with the feeding port of the carbonization receiver; a feeding disperser for uniformly dispersing materials into the carbonization reactor is also arranged at the bottom of the carbonization reactor; and the feeding disperser is communicated with a feeding hole of the carbonization reactor. According to the carbonization purification system, the reaction efficiency and the yield can be improved, accurate control over the reaction process is achieved, the device flexibility and adaptability are high, the production continuity is high, and the obtained product is high in purity and good in performance.

Description

Technical Field

[0001] This utility model relates to the field of battery material preparation equipment technology, and in particular to a high-efficiency and low-cost carbonation purification system for preparing lithium carbonate. Background Technology

[0002] The primary method for producing battery-grade lithium carbonate from industrial-grade lithium carbonate is carbonation purification. This method involves introducing carbon dioxide to convert the less soluble lithium carbonate into more soluble lithium bicarbonate, while removing most impurities (such as calcium carbonate). 2+ Mg 2+ (etc.) are not carbonized and are removed by filtration as insoluble carbonates. Then, the lithium bicarbonate solution is heated to decompose it into battery-grade lithium carbonate.

[0003] Existing carbonization equipment typically uses carbonization towers or carbonization reactors, primarily employing stirred carbonization towers equipped with jackets or coils. These towers require high stirring intensity and rotational speeds, making them prone to leakage at the stirring seals. Wear on the stirring shaft can contaminate the material, and a certain amount of carbon dioxide leaks from the shaft, resulting in carbon dioxide loss. Existing technologies also include practical examples of continuous carbonization towers without stirring. The main process flow is as follows: material is pumped from the top of the carbonization tower into the first-stage carbonization tower by a feed pump; material from the first-stage tower is pumped from the bottom to the second-stage tower; material from the second-stage tower is pumped from the bottom to the third-stage tower; material from the third-stage tower is pumped from the bottom to the fourth-stage tower; material from the fourth-stage tower is pumped from the bottom to the fifth-stage tower; and material from the fifth-stage tower is pumped from the bottom to a post-carbonization buffer tank for buffering. Each stage of the carbonization tower has a carbon dioxide inlet at the bottom and is equipped with an external heat exchanger and a circulating pump. However, the aforementioned continuous carbonization tower has many carbonization stages, consumes a large amount of carbon dioxide, has a slow carbonization rate, and when the coarse carbon particles are large, the large particles do not easily react fully with carbon dioxide. After multiple carbonization stages, they still exist in the solution as small particles and are filtered by subsequent filtration devices, affecting the lithium carbonate yield. Utility Model Content

[0004] This invention provides a carbonization and purification system for preparing lithium carbonate, which solves the technical problems mentioned in the background art, such as high equipment cost, large carbon dioxide consumption, slow carbonization speed, and low lithium carbonate yield.

[0005] To solve the above-mentioned technical problems, the technical solution proposed by this utility model is as follows:

[0006] A carbonation purification system for preparing lithium carbonate includes a slurry preparation device, a gas-slurry shear mixing device, a carbonation device, and a post-processing device connected in sequence. The carbonation device includes a carbonation reactor and a carbonation receiver connected in sequence. The carbonation reactor has an inlet at the bottom and an overflow at the top, with the overflow connected to the inlet of the carbonation receiver. A feed disperser is also provided at the bottom of the carbonation reactor to uniformly disperse the material inside, and this feed disperser is connected to the inlet of the carbonation reactor. The slurry preparation device prepares a slurry of coarse lithium carbonate and water in a specific ratio. The resulting slurry is sheared and mixed with carbon dioxide gas by the gas-slurry shear mixing device and then sent to the carbonation device for carbonation. The lithium carbonate slurry, thoroughly mixed with carbon dioxide, enters from the feed disperser at the bottom of the carbonation reactor. Due to the small particle size of the lithium carbonate particles and the dispersion effect of the feed disperser's nozzles, the lithium carbonate slurry does not precipitate in the carbonation reactor, eliminating the need for a circulation pump, resulting in a simple structure and reduced energy consumption. After a full reaction, the resulting lithium bicarbonate solution overflows from the top to the carbonization receiver and is then sent to subsequent process stages for further processing.

[0007] As a further preferred embodiment of the above technical solution, the feed disperser is a gas pipe extending horizontally from the feed inlet of the carbonization reactor to the side wall of the carbonization reactor, and the gas pipe is provided with multiple nozzles facing the interior of the carbonization reactor. This feed disperser structure can more accurately disperse the material into the interior of the carbonization reactor, and the multiple nozzles can make the material dispersion more uniform and fine, further promoting the mixing of the material with carbon dioxide, improving the sufficiency and uniformity of the reaction, thereby improving the reaction formation effect and yield of lithium carbonate, and also helping to improve the stability of product quality.

[0008] As a further preferred embodiment of the above technical solution, the carbonization reactor is equipped with heat exchange coils extending from bottom to top. The heat exchange coils allow for effective temperature control during the carbonization reaction. Since the carbonization reaction may generate heat, the heat exchange coils can adjust the reaction temperature in a timely manner, ensuring the reaction proceeds at a suitable temperature. This improves the reaction rate and selectivity, and avoids adverse effects on lithium carbonate formation and product quality caused by excessively high or low temperatures, thereby improving product quality and production efficiency.

[0009] As a further preferred embodiment of the above technical solution, the carbonization receiver has an air inlet and an outlet at its bottom. The outlet of the carbonization receiver is connected to the inlet of the post-processing device, and the air inlet of the carbonization receiver is connected to a carbon dioxide gas source. The air inlet at the bottom of the carbonization receiver allows carbon dioxide to further react with unreacted materials, providing a safety function, making the carbonization reaction more thorough, the product quality more stable, and improving the utilization rate of carbon dioxide and the conversion rate of the reaction.

[0010] As a further preferred embodiment of the above technical solution, the gas-slurry shear mixing device is a shear pump. The shear pump has a feed inlet, an air inlet, and a discharge outlet. The air inlet of the shear pump is connected to a carbon dioxide gas source, and the discharge outlet of the shear pump is connected to the feed inlet of the carbonation device. Through the instantaneous and intense frictional shearing, centrifugal compression, and impact of the shear pump, carbon dioxide molecules and lithium carbonate continuously collide and break, generating a gas explosion effect. This reduces the lithium carbonate particle size (D50) to below 5 μm. Simultaneously, the carbon dioxide and lithium carbonate slurry are instantly and effectively mixed, accelerating the carbonation reaction rate, avoiding incomplete carbonation of large solid particles, improving the lithium carbonate yield, increasing the contact area between the carbon dioxide gas and the slurry, and enhancing the carbonation reaction efficiency.

[0011] As a further preferred embodiment of the above technical solution, the air inlet of the shear pump is equipped with a flow meter and a regulating valve, and the feed inlet of the shear pump is equipped with a mass flow meter and a regulating valve. By installing flow meters and regulating valves at the air inlet and feed inlet, the amount of carbon dioxide and materials entering the shear pump can be precisely controlled, achieving precise regulation of the reaction process. This ensures that the reaction proceeds at the optimal material ratio and gas flow rate, improving the stability of the reaction and the consistency of product quality, and avoiding reaction abnormalities or product quality fluctuations caused by improper control of material or gas quantities.

[0012] As a further preferred embodiment of the above technical solution, the post-processing device includes a filtration device, a purification device, a pyrolysis device, a solid-liquid separation device, and a drying and crushing device connected in sequence. By rationally configuring each stage of the post-processing device, comprehensive treatment of the material after the carbonization reaction can be achieved. The filtration device removes insoluble impurities, the purification device further removes residual soluble impurities, the pyrolysis device decomposes lithium bicarbonate into lithium carbonate, the solid-liquid separation device separates solid lithium carbonate, and the drying and crushing device processes the lithium carbonate into a product form that meets the requirements. Through the coordination of these stages, the purity and quality of the lithium carbonate product can be improved, enabling it to meet the standards of battery-grade lithium carbonate.

[0013] As a further preferred embodiment of the above technical solution, the filtration device includes a plate and frame filter press and a precision filter arranged sequentially. The plate and frame filter press can perform preliminary solid-liquid separation on the material, removing larger particles of impurities and most of the liquid, thus reducing the burden on the subsequent precision filter. The precision filter can further filter out fine impurity particles, improving the filtration effect and ensuring that the material entering the subsequent processing stage is purer, thereby improving the purity of the final product, lithium carbonate, and reducing the impact of impurities on product quality.

[0014] As a further preferred embodiment of the above technical solution, the pyrolysis device is a pyrolysis reactor or a pyrolysis tower. As a pyrolysis device, the pyrolysis reactor or pyrolysis tower can provide suitable reaction space and conditions for the decomposition of lithium bicarbonate, ensuring the smooth progress of the pyrolysis reaction, effectively converting lithium bicarbonate into lithium carbonate, improving the lithium carbonate production efficiency and product quality. At the same time, the selection of the pyrolysis device also offers a certain degree of flexibility, allowing for a reasonable selection based on actual production needs and process conditions.

[0015] As a further preferred embodiment of the above technical solution, the drying and crushing device includes a drying component and a crushing component. The drying component is a disc dryer, an electric rotary kiln, or a propeller blade; the crushing component is an air jet mill. Different drying components can be selected according to the characteristics of the material and production requirements to effectively remove moisture from lithium carbonate and ensure the dryness of the product. The air jet mill, as a crushing component, can crush lithium carbonate particles into finer, more uniform particles, meeting the particle size requirements of battery-grade lithium carbonate, improving product performance and applicability. At the same time, air jet milling is a relatively gentle method and will not adversely affect the chemical properties of lithium carbonate.

[0016] This utility model has the following beneficial effects:

[0017] The carbonization purification system for preparing lithium carbonate of this invention can improve reaction efficiency and yield, achieve precise control of the reaction process, and has strong flexibility and adaptability, strong production continuity, and high product purity and excellent performance. It is different from the traditional carbonization tower with stirring, which is prone to leakage at the stirring seal, wear of the stirring shaft, and leakage of carbon dioxide from the stirring shaft. It also improves the shortcomings of the traditional non-stirred continuous carbonization tower, such as multiple carbonization stages, large carbon dioxide consumption, slow carbonization speed, and insufficient reaction of large particles. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the carbonization and purification system for preparing lithium carbonate in Example 1.

[0019] Figure 2 This is a schematic diagram of the carbonization reactor in Example 1.

[0020] Figure 3 This is a schematic cross-sectional view of the carbonization reactor in Example 1.

[0021] Legend:

[0022] 1. Pulping device; 2. Gas-slurry shear mixing device; 31. Carbonization reactor; 311. Feed inlet; 312. Overflow outlet; 313. Feed disperser; 3131. Gas pipeline; 3132. Nozzle; 314. Heat exchange coil; 315. Gas outlet; 32. Carbonization receiver; 41. Filtration device; 42. Impurity removal device; 43. Pyrolysis device; 44. Solid-liquid separation device; 45. Drying and crushing device; 5. Carbon dioxide gas source. Detailed Implementation

[0023] The present invention will be described in detail below with reference to the embodiments and accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered by the claims.

[0024] Example 1:

[0025] The carbonization and purification apparatus for preparing lithium carbonate from lithium in this embodiment, such as Figure 1 As shown, it includes a pulping device 1, an air-slurry shear mixing device 2, a carbonization device, a filtration device 41, an impurity removal device 42, a pyrolysis device 43, a solid-liquid separation device 44, and a drying and crushing device 45, which are arranged and connected in sequence according to the slurry flow direction.

[0026] The pulping device 1 is used to prepare a slurry by mixing pure water and crude lithium carbonate at a mass ratio of 20~24:1. The slurry is connected to a slurry delivery pump via a pipeline and then transported to the gas-slurry shear mixing device 2. The gas-slurry shear mixing device 2 is a shear pump (a conventional shear pump with a shearing disc). The shear pump has an inlet, an air inlet, and an outlet. The outlet of the pulping device 1 is connected to the inlet of the shear pump via the slurry delivery pump. The air inlet of the shear pump is connected to a carbon dioxide gas source 5. The outlet of the shear pump is connected to the inlet of the carbonation device. The inlet of the shear pump is equipped with a mass flow meter and a regulating valve to control the feed flow rate to 18~20 m³ / h. The air inlet of the shear pump is equipped with a gas flow meter and a regulating valve to control the hourly carbon dioxide intake flow rate to be 1 times the theoretical hourly lithium carbonate content. The shear pump enables the carbon dioxide and lithium carbonate slurry to be mixed instantly and effectively.

[0027] The carbonization apparatus includes a carbonization reactor 31 and a carbonization receiver 32, such as Figure 2 and Figure 3As shown, the carbonization reactor 31 has a feed inlet 311 at the bottom and an overflow outlet 312 and a gas outlet 315 at the top. An internal heat exchange coil 314 extends from bottom to top. The feed inlet 311 of the carbonization reactor 31 is connected to a feed disperser 313, which extends horizontally from the feed inlet 311 to a cross-shaped gas pipe 3131 on the side wall of the carbonization reactor 31, with multiple upward-facing nozzles 3132 on it. The carbonization receiver 32 has a feed inlet at the top, connected to the overflow outlet 312 of the carbonization reactor 31 via a pipe, and a feed outlet at the bottom. The air inlet is connected to the carbon dioxide gas source 5, and a gas flow meter and regulating valve are also installed at the inlet. The outlet is connected to the inlet of the filter device 41. The slurry enters from the bottom of the carbonization reactor 31 through the pipeline. After being fully carbonized in the carbonization reactor 31, it overflows from the overflow port 312 at the top of the carbonization reactor 31 to the carbonization receiver 32. Carbon dioxide is introduced into the bottom of the carbonization receiver 32. The flow rate of carbon dioxide is controlled by the gas flow meter and regulating valve to be 0.05 to 0.1 times the gas flow rate of the gas-slurry shear mixing device 2. The lithium bicarbonate solution is output from the bottom of the carbonization receiver 32.

[0028] The filtration device 41 consists of a plate and frame filter press and a precision filter arranged in sequence. The outlet of the precision filter is connected to the inlet of the impurity removal device 42. After the lithium bicarbonate solution passes through the filtration device 41 to remove insoluble impurities, it enters the impurity removal device 42.

[0029] The impurity removal device 42 is a resin impurity removal device, and its outlet is connected to the inlet of the pyrolysis device 43. The lithium bicarbonate solution enters the pyrolysis device 43 after further removing impurities such as calcium, magnesium, and boron from the solution through the impurity removal device 42.

[0030] The pyrolysis device 43 is a pyrolysis tower, and its outlet is connected to the inlet of the solid-liquid separation device 44. After the lithium bicarbonate solution is pyrolyzed, lithium carbonate is generated and sent to the solid-liquid separation device 44.

[0031] The solid-liquid separation device 44 is a flat-plate centrifuge, whose outlet is connected to the inlet of the drying and crushing device 45. The flat-plate centrifuge separates and removes the mother liquor, and outputs solid lithium carbonate into the drying and crushing device 45.

[0032] The drying and crushing device 45 includes a drying component and a crushing component. The drying component is a disc dryer, and the crushing component is an air jet mill. After being processed by the drying and crushing device 45, battery-grade lithium carbonate is obtained.

[0033] The above description is merely a preferred embodiment of this utility model, and the protection scope of this utility model is not limited to the above embodiments. For those skilled in the art, improvements and modifications obtained without departing from the technical concept of this utility model should also be considered within the protection scope of this utility model.

[0034] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A carbonization purification system for preparing lithium carbonate, characterized in that, The device includes a pulping device (1), a gas-slurry shear mixing device (2), a carbonization device, and a post-processing device connected in sequence. The carbonization device includes a carbonization reactor (31) and a carbonization receiver (32) connected in sequence. The bottom of the carbonization reactor (31) is provided with an inlet (311) and the top is provided with an overflow port (312). The overflow port (312) of the carbonization reactor (31) is connected to the inlet of the carbonization receiver (32). The bottom of the carbonization reactor (31) is also provided with a feed disperser (313) for uniformly dispersing the material into the interior of the carbonization reactor (31). The feed disperser (313) is connected to the inlet (311) of the carbonization reactor (31).

2. The carbonization purification system for preparing lithium carbonate according to claim 1, characterized in that, The feed disperser (313) is a gas pipe (3131) that extends horizontally from the feed inlet (311) of the carbonization reactor (31) to the side wall of the carbonization reactor (31), and the gas pipe (3131) is provided with a plurality of nozzles (3132) facing the interior of the carbonization reactor (31).

3. The carbonization purification system for preparing lithium carbonate according to claim 1, characterized in that, The carbonization reactor (31) is equipped with heat exchange coils (314) extending from bottom to top inside.

4. The carbonization purification system for preparing lithium carbonate according to claim 1, characterized in that, The bottom of the carbonization receiver (32) is provided with an air inlet and a discharge outlet. The discharge outlet of the carbonization receiver (32) is connected to the inlet of the post-processing device, and the air inlet of the carbonization receiver (32) is connected to the carbon dioxide gas source (5).

5. The carbonization and purification system for preparing lithium carbonate according to any one of claims 1-4, characterized in that, The gas-slurry shear mixing device (2) is a shear pump. The shear pump has a feed inlet, an air inlet and a discharge outlet. The air inlet of the shear pump is connected to the carbon dioxide gas source (5), and the discharge outlet of the shear pump is connected to the feed inlet of the carbonization device.

6. The carbonization purification system for preparing lithium carbonate according to claim 5, characterized in that, The air inlet of the shear pump is equipped with a flow meter and a regulating valve, and the feed inlet of the shear pump is equipped with a mass flow meter and a regulating valve.

7. The carbonization purification system for preparing lithium carbonate according to any one of claims 1-4, characterized in that, The post-processing device includes a filtration device (41), a purification device (42), a pyrolysis device (43), a solid-liquid separation device (44), and a drying and crushing device (45) connected in sequence.

8. The carbonization purification system for preparing lithium carbonate according to claim 7, characterized in that, The filtration device (41) includes a plate and frame filter press and a precision filter arranged in sequence.

9. The carbonization purification system for preparing lithium carbonate according to claim 7, characterized in that, The pyrolysis device (43) is a pyrolysis reactor or a pyrolysis tower.

10. The carbonization purification system for preparing lithium carbonate according to claim 7, characterized in that, The drying and crushing device (45) includes a drying component and a crushing component. The drying component is a disc dryer, an electric rotary kiln, or a propeller blade; the crushing component is an air jet mill.

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