A pyrolysis device for battery-grade lithium carbonate with uniform particle size

Abstract

The utility model discloses a kind of battery-grade lithium carbonate pyrolysis devices of uniform granularity, including pyrolysis tower, reaction cavity is inside pyrolysis tower, inlet, discharge port and exhaust port are equipped with and communicate with reaction cavity on pyrolysis tower, lithium bicarbonate solution is added into reaction cavity from inlet, it is decomposed into lithium carbonate and carbon dioxide, water in reaction cavity, carbon dioxide produced by pyrolysis is directly discharged from exhaust port, solid-liquid mixture formed after pyrolysis is discharged from discharge port, by installing pressure sensor in reaction cavity, install exhaust valve in exhaust port, realize the pressure regulation in reaction cavity, maintain the constant-voltage environment in reaction cavity, avoid lithium bicarbonate solution in reaction cavity local supersaturation, reduce crystal nucleus disorder generation, to obtain the lithium carbonate crystal of uniform granularity, solved the problem that product granularity is uneven or unqualified in traditional process.

Description

Technical Field

[0001] This utility model belongs to the field of lithium carbonate preparation technology, and relates to the refining and purification of industrial-grade lithium carbonate to prepare battery-grade lithium carbonate, specifically a battery-grade lithium carbonate pyrolysis device with uniform particle size. Background Technology

[0002] Lithium carbonate can be divided into industrial-grade lithium carbonate and battery-grade lithium carbonate according to the purity and impurity content of the product. Each has its own corresponding standards. Compared with industrial-grade lithium carbonate, battery-grade lithium carbonate has higher purity, fewer impurities, and better performance.

[0003] Existing technologies typically use industrial-grade lithium carbonate as a raw material, which is then refined and purified to prepare battery-grade lithium carbonate. Specifically, for example... Figure 1 As shown, after industrial-grade lithium carbonate is dissolved, its solubility is increased by carbonation with carbon dioxide. After filtration to remove magnetism and impurities, the resulting lithium bicarbonate solution is sent to a pyrolysis unit. The carbon dioxide obtained after pyrolysis is recycled back to the carbonation unit for reuse. The slurry obtained after pyrolysis is sent to a separation unit for solid-liquid separation. The separated pyrolysis mother liquor is recycled back to the slurry preparation unit for reuse. The separated solid particles are dried, dehydrated, crushed, demagnetized, and packaged to obtain battery-grade lithium carbonate products. However, battery-grade lithium carbonate products from actual production lines often exhibit uneven particle size, and some batches may even have unqualified particle sizes. The particle size and shape of crystals formed during pyrolysis directly affect the particle size of the product. Therefore, improvements are considered to the pyrolysis process to obtain battery-grade lithium carbonate products with uniform particle size. Utility Model Content

[0004] To address the technical problems existing in the background art, this utility model proposes a battery-grade lithium carbonate pyrolysis device with uniform particle size. Through thermodynamic optimization, waste heat recovery, intelligent pressure regulation and resource recycling design, it improves the particle size uniformity of battery-grade lithium carbonate products while achieving comprehensive benefits such as energy saving, consumption reduction, efficient resource utilization and improved production stability.

[0005] The objective of this utility model can be achieved through the following technical solutions:

[0006] A battery-grade lithium carbonate pyrolysis device with uniform particle size includes: a pyrolysis tower with a reaction chamber inside; an inlet, an outlet, and an exhaust port connected to the reaction chamber; a lithium bicarbonate solution is added to the reaction chamber through the inlet and thermally decomposed into lithium carbonate, carbon dioxide, and water within the reaction chamber; the carbon dioxide generated during pyrolysis is directly discharged through the exhaust port; during the pyrolysis process, because the solubility of lithium carbonate in water is much lower than that of lithium bicarbonate in water, a large amount of lithium carbonate crystallizes and precipitates to form a solid-liquid mixture, which is discharged through the outlet; a pressure sensor is installed inside the reaction chamber to collect pressure data in real time; and an exhaust valve is installed inside the exhaust port to regulate the pressure inside the reaction chamber by opening / closing the exhaust valve.

[0007] Furthermore, the pressure sensor is connected to the controller to transmit the collected reaction chamber pressure data to the controller in real time. The controller is electrically connected to the exhaust valve. If the reaction chamber pressure data is higher than a preset first threshold, the controller opens the exhaust valve. If the reaction chamber pressure data is lower than a preset second threshold, the controller closes the exhaust valve, so that the pressure inside the reaction chamber remains stable. By creating a constant pressure environment, local oversaturation of the lithium bicarbonate solution in the reaction chamber is avoided, and disordered crystal nuclei are reduced, thereby obtaining lithium carbonate crystals with uniform particle size.

[0008] Furthermore, the pyrolysis device also includes: a gas storage tank and a gas replenishment pump. One end of the gas storage tank is connected to the exhaust port to recover and temporarily store the carbon dioxide discharged from the exhaust port. The other end of the gas storage tank is connected to the gas replenishment pump. The pyrolysis tower is provided with a gas replenishment port that communicates with the reaction chamber. The gas replenishment pump is connected to the gas replenishment port to send the carbon dioxide in the gas storage tank back into the reaction chamber, thereby further regulating the pressure in the reaction chamber. A one-way valve is provided in the gas replenishment port to prevent gas or liquid in the reaction chamber from flowing back into the gas replenishment port.

[0009] Furthermore, the air supply pump is electrically connected to the controller. If the pressure data of the reaction chamber is lower than the preset third threshold, the controller turns on the air supply pump. If the pressure data of the reaction chamber is higher than the preset first threshold, the controller turns off the air supply pump, thereby further maintaining the stability of the internal pressure of the reaction chamber and enabling rapid adjustment when the pressure is low.

[0010] Furthermore, the pyrolysis tower has a heat exchange chamber located in the interlayer between the reaction chamber and the side wall to indirectly heat the lithium bicarbonate solution entering the reaction chamber with steam, ensuring that no other impurities enter the solution system, the solution is not diluted, the obtained lithium carbonate is of high quality, and the pyrolysis heat utilization is high. The pyrolysis tower is equipped with a steam inlet and a steam outlet connected to the heat exchange chamber. High-temperature steam enters the heat exchange chamber from the steam inlet and is discharged from the steam outlet after releasing heat.

[0011] Furthermore, the pyrolysis device also includes: a steam generator and a circulating pump. One end of the steam generator is connected to a steam inlet to send the generated high-temperature steam from the steam inlet into the heat exchange chamber. The other end of the steam generator is connected to the circulating pump, and the circulating pump is connected to a steam outlet to send the released steam or condensate into the steam generator for recycling.

[0012] Furthermore, the pyrolysis apparatus also includes a preheater, which has a preheating chamber. A low-temperature lithium bicarbonate solution is fed into the preheating chamber from the input end of the preheating chamber for preheating. The output end of the preheating chamber is connected to the feed inlet so that the preheated lithium bicarbonate solution is fed into the reaction chamber from the feed inlet, thereby increasing the pyrolysis feed temperature and reducing steam consumption.

[0013] Furthermore, the outlet of the pyrolysis tower is connected to a centrifuge to send the solid-liquid mixture containing a large amount of lithium carbonate crystals generated by pyrolysis into the centrifuge for solid-liquid separation to obtain lithium carbonate crystals. The centrifuge has a liquid outlet at the bottom to discharge the separated pyrolysis mother liquor.

[0014] Furthermore, the preheater adopts a single-pass shell-and-tube heat exchanger. The preheating chamber is equipped with heat exchange tubes, and the inlet end of the heat exchange tubes is connected to the outlet of the centrifuge to send the high-temperature pyrolysis mother liquor separated by the centrifuge into the heat exchange tubes. The high-temperature pyrolysis mother liquor in the heat exchange tubes exchanges heat with the low-temperature lithium bicarbonate solution in the preheating chamber during the flow process, realizing the heat recovery and reuse of the high-temperature pyrolysis mother liquor. The pyrolysis mother liquor after heat release is discharged from the outlet end of the heat exchange tubes for recovery and reuse.

[0015] The beneficial effects of this utility model are:

[0016] 1. Improved particle size uniformity: By using a pressure sensor and controller to adjust the exhaust valve and make-up pump, a constant pressure environment in the reaction chamber is maintained, avoiding local oversaturation of the lithium bicarbonate solution and reducing disordered crystal nuclei formation. This results in lithium carbonate crystals with uniform particle size distribution, solving the problem of uneven or unqualified product particle size in traditional processes. Furthermore, the dynamic pressure control system, composed of a pressure sensor, controller, and exhaust valve / make-up pump, can achieve precise and stable pressure in the reaction chamber, avoiding human intervention errors, ensuring batch-to-batch consistency, and making it suitable for large-scale production.

[0017] 2. Efficient use of energy and resources: The high-temperature pyrolysis mother liquor is used to preheat the low-temperature lithium bicarbonate solution through the preheater to recover waste heat and reduce steam consumption. The steam generator and the circulating pump form a steam circulation system to recover the steam or condensate after heat exchange and reheat it for reuse, thereby reducing raw material waste and realizing closed-loop utilization of resources.

[0018] 3. Product quality and production efficiency optimization: The jacketed heat exchange chamber design uses indirect steam heating to avoid introducing impurities into the solution, ensuring the high purity of battery-grade lithium carbonate.

[0019] In summary, the battery-grade lithium carbonate pyrolysis device provided in this application, through thermodynamic optimization, waste heat recovery, intelligent pressure regulation, and resource recycling design, improves the particle size uniformity of battery-grade lithium carbonate products while achieving comprehensive benefits such as energy saving, efficient resource utilization, and improved production stability. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of an existing production system for refining and purifying industrial-grade lithium carbonate to prepare battery-grade lithium carbonate.

[0021] Figure 2 This is a schematic diagram of the present invention.

[0022] Figure 3 This is a schematic diagram of the pyrolysis tower of this utility model. Detailed Implementation

[0023] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0024] This invention provides a battery-grade lithium carbonate pyrolysis device with uniform particle size, in such cases... Figure 1 In the battery-grade lithium carbonate production system shown, the pyrolysis unit is connected between the filtration unit and the separation unit. The filtration unit filters the lithium bicarbonate solution formed after the industrial-grade lithium carbonate is dissolved and carbonized to remove magnetism and impurities, resulting in a refined lithium bicarbonate solution. The pyrolysis unit thermally decomposes the lithium bicarbonate into lithium carbonate, carbon dioxide, and water. Since the solubility of lithium carbonate in water is much lower than that of lithium bicarbonate in water, a large amount of lithium carbonate crystallizes out to form a solid-liquid mixture. This mixture is then separated by the subsequent separation unit. Finally, the separated solid particles are dried, dehydrated, crushed, and demagnetized to obtain the battery-grade lithium carbonate product.

[0025] like Figure 2-3As shown, the pyrolysis apparatus includes: a pyrolysis tower 1, a preheater 2, a steam generator 3, and a circulating pump 4. The pyrolysis tower 1 has a reaction chamber and a heat exchange chamber, with the heat exchange chamber located in the interlayer between the reaction chamber and the side wall of the pyrolysis tower 1. The pyrolysis tower 1 is equipped with a feed inlet 11, a discharge outlet 12, and an exhaust outlet 13 communicating with the reaction chamber, as well as a steam inlet 15 and a steam outlet 16 communicating with the heat exchange chamber. The feed inlet 11 and exhaust outlet 13 are both located at the top of the pyrolysis tower 1. A lithium bicarbonate solution is added to the reaction chamber through the feed inlet 11, where it undergoes thermal decomposition into lithium carbonate, carbon dioxide, and water. The carbon dioxide produced during pyrolysis is directly discharged through the exhaust outlet 13. The discharge outlet 12 is located at the bottom of the pyrolysis tower 1, discharging the solid-liquid mixture containing lithium carbonate crystals formed after pyrolysis. Both the steam inlet 15 and the steam outlet 16 are located on the side wall of the pyrolysis tower 1. High-temperature steam is introduced into the heat exchange chamber through the steam inlet 15. The lithium bicarbonate solution in the reaction chamber is indirectly heated by steam in the heat exchange chamber, which ensures that no other impurities enter the solution, does not dilute the solution, and produces high-quality lithium carbonate with high pyrolysis heat utilization. After releasing heat, the solution is discharged from the steam outlet 16.

[0026] The outlet 12 of the pyrolysis tower 1 is connected to the centrifuge of the separation device. The solid-liquid mixture containing lithium carbonate crystals enters the centrifuge from the outlet 12 for solid-liquid separation to obtain lithium carbonate crystals. The centrifuge has a liquid outlet at the bottom to discharge the separated high-temperature pyrolysis mother liquor.

[0027] Preheater 2 employs a single-pass shell-and-tube heat exchanger. Preheater 2 contains a preheating chamber with heat exchange tubes. The inlet of the preheating chamber is connected to a pre-filter. The filtered low-temperature refined lithium bicarbonate solution enters the preheating chamber from the inlet. The inlet of the heat exchange tubes is connected to the outlet of a centrifuge to send the high-temperature pyrolysis mother liquor separated by the centrifuge into the heat exchange tubes to preheat the low-temperature lithium bicarbonate solution in the preheating chamber. The high-temperature pyrolysis mother liquor in the heat exchange tubes reacts with the low-temperature lithium bicarbonate solution in the preheating chamber. The lithium bicarbonate solution undergoes heat exchange during flow, enabling the recovery and reuse of heat from the high-temperature pyrolysis mother liquor. The output end of the preheating chamber is connected to the feed inlet 11 of the pyrolysis tower 1, allowing the preheated lithium bicarbonate solution to be fed into the reaction chamber from the feed inlet 11. This increases the temperature of the pyrolysis feed, reduces steam consumption, and saves production energy. The output end of the heat exchange tube can be connected to the pre-positioned slurry preparation device, allowing the exothermic pyrolysis mother liquor to be discharged to the slurry preparation device for recycling, further saving production resources.

[0028] One end of the steam generator 3 is connected to the steam inlet 15 of the pyrolysis tower 1 to send the generated high-temperature steam from the steam inlet 15 into the heat exchange chamber. The other end of the steam generator 3 is connected to the circulating pump 4, which is connected to the steam outlet 16 of the pyrolysis tower 1 to send the released steam or condensate back into the steam generator 3 to generate high-temperature steam, thereby realizing the recycling of steam and saving resources.

[0029] A pressure sensor is installed inside the reaction chamber of the pyrolysis tower 1 to collect pressure data in real time. An exhaust valve 5 is installed inside the exhaust port 13 of the pyrolysis tower 1 to regulate the pressure inside the reaction chamber by opening and closing the exhaust valve 5. The pressure sensor is communicatively connected to a controller, transmitting the collected reaction chamber pressure data to the controller in real time. The controller is electrically connected to the exhaust valve 5. The controller analyzes and processes the real-time data uploaded by the pressure sensor. If the reaction chamber pressure data is higher than a preset first threshold, the controller opens the exhaust valve 5; if the reaction chamber pressure data is lower than a preset second threshold, the controller closes the exhaust valve 5. This maintains a stable pressure inside the reaction chamber, preventing localized supersaturation of the lithium bicarbonate solution within the reaction chamber and reducing disordered crystal nuclei formation, thereby obtaining lithium carbonate crystals with uniform particle size.

[0030] The pyrolysis apparatus also includes a gas storage tank 6 and a gas replenishment pump 7. One end of the gas storage tank 6 is connected to the exhaust port 13 of the pyrolysis tower 1 to recover and temporarily store the carbon dioxide discharged from the exhaust port 13. The other end of the gas storage tank 6 is connected to the gas replenishment pump 7. A gas replenishment port 14 communicating with the reaction chamber is also provided on the side wall at the bottom of the pyrolysis tower 1. The gas replenishment pump 7 is connected to the gas replenishment port 14 to send the carbon dioxide in the gas storage tank 6 back into the reaction chamber, further regulating the pressure in the reaction chamber. At the same time, carbon dioxide gas is introduced from the bottom of the reaction chamber, and bubbles emerge in the lithium bicarbonate solution. The bubbles adhere to the inner wall of the reaction chamber and rise, using the bubble flow to stir the lithium bicarbonate solution, accelerating the lithium bicarbonate pyrolysis reaction, improving the lithium bicarbonate pyrolysis efficiency, and reducing the phenomenon of wall adhesion in the reaction chamber. A one-way valve 8 is provided in the gas replenishment port 14 to prevent gas or liquid in the reaction chamber from flowing back into the gas replenishment port.

[0031] The air supply pump 7 is electrically connected to the controller. If the pressure data of the reaction chamber is lower than the preset third threshold, the controller turns on the air supply pump 7. If the pressure data of the reaction chamber is higher than the preset first threshold, the controller turns off the air supply pump 7, thereby further maintaining the stability of the internal pressure of the reaction chamber and enabling rapid adjustment when the pressure is low.

[0032] The gas storage tank 6 is also equipped with a gas outlet, which contains a gas outlet valve. The gas outlet can be connected to the pre-installed carbonization device. When the gas storage tank 6 is full of carbon dioxide gas, the gas outlet valve can be opened to send the carbon dioxide gas into the carbonization device for recycling, which further saves production resources.

[0033] The above description is merely an example and illustration of the structure of this utility model. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the structure of the utility model or exceed the scope defined in the claims, they should all fall within the protection scope of this utility model.

Claims

1. A battery-grade lithium carbonate pyrolysis device with uniform particle size, characterized in that, include: The pyrolysis tower (1), gas storage tank (6), gas replenishment pump (7), and controller are provided. The pyrolysis tower (1) has a reaction chamber inside, and a pressure sensor is installed in the reaction chamber. The pyrolysis tower (1) is provided with an inlet (11), an outlet (12), and an exhaust port (13) that are connected to the reaction chamber. An exhaust valve (5) is installed in the exhaust port (13). One end of the gas storage tank (6) is connected to the exhaust port (13), and the other end is connected to the gas replenishment pump (7). The pyrolysis tower (1) is provided with a gas replenishment port (14) that is connected to the reaction chamber. The gas replenishment pump (7) is connected to the gas replenishment port (14). The pressure sensor is connected to the controller. The controller is electrically connected to the exhaust valve (5) and the gas replenishment pump (7) respectively.

2. The pyrolysis apparatus according to claim 1, characterized in that, The pressure sensor transmits the collected reaction chamber pressure data to the controller in real time: if the reaction chamber pressure data is higher than the preset first threshold, the controller opens the exhaust valve (5); if the reaction chamber pressure data is lower than the preset second threshold, the controller closes the exhaust valve (5); if the reaction chamber pressure data is lower than the preset third threshold, the controller opens the air supply pump (7); if the reaction chamber pressure data is higher than the preset first threshold, the controller closes the air supply pump (7).

3. The pyrolysis apparatus according to claim 1, characterized in that, A one-way valve (8) is installed inside the air supply port (14).

4. The pyrolysis apparatus according to claim 1, characterized in that, The pyrolysis tower (1) has a heat exchange chamber located in the interlayer between the reaction chamber and the side wall. The pyrolysis tower (1) is provided with a steam inlet (15) and a steam outlet (16) connected to the heat exchange chamber.

5. The pyrolysis apparatus according to claim 4, characterized in that, Also includes: Steam generator (3) and circulation pump (4). One end of the steam generator (3) is connected to the steam inlet (15), and the other end is connected to the circulation pump (4). The circulation pump (4) is connected to the steam outlet (16).

6. The pyrolysis apparatus according to claim 1, characterized in that, Also includes: The preheater (2) has a preheating chamber inside, and the output end of the preheating chamber is connected to the feed inlet (11).

7. The pyrolysis apparatus according to claim 6, characterized in that, The outlet (12) of the pyrolysis tower (1) is connected to a centrifuge, and the bottom of the centrifuge has a liquid outlet.

8. The pyrolysis apparatus according to claim 7, characterized in that, The preheater (2) adopts a single-pass shell-and-tube heat exchanger. The preheating chamber is equipped with heat exchange tubes, and the input end of the heat exchange tubes is connected to the liquid outlet of the centrifuge.

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