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CN-122010149-A - Method for preparing battery-grade lithium carbonate based on continuous flow dynamic coupling micro-reaction system

CN122010149ACN 122010149 ACN122010149 ACN 122010149ACN-122010149-A

Abstract

The invention discloses a method for preparing battery-grade lithium carbonate based on a continuous flow coupling micro-reaction system. The method adopts an ammonia process route that firstly carbon dioxide is introduced into a micro-channel reactor to react with ammonia water to generate ammonium carbonate solution, and then the ammonium carbonate solution and lithium chloride solution are continuously injected into an autonomously designed continuous flow dynamic micro-reactor. The continuous flow dynamic micro-reactor effectively breaks precipitated solid particles through the shearing force generated by internal high-speed stirring, solves the problem that the traditional micro-reactor is easy to block, and realizes the long-term stable continuous operation of a solid-containing system. The particle size distribution and impurity content of the lithium carbonate can be accurately controlled by adjusting the reaction temperature, the stirring rotation speed, the antisolvent proportion and the raw material proportion. The purity of the lithium carbonate prepared by the method is higher than 99.5wt%, and the lithium carbonate avoids sodium ion pollution, has the advantages of high efficiency, high automation degree, environmental friendliness and the like, and has remarkable industrial application prospect.

Inventors

  • SU YUANHAI
  • DU HANGYU
  • GAO ZHANGYI
  • SHANG MINJING

Assignees

  • 上海交通大学

Dates

Publication Date
20260512
Application Date
20260312

Claims (10)

  1. 1. A method for preparing battery grade lithium carbonate based on a continuous flow coupling micro-reaction system is characterized by comprising the following steps of (1) introducing carbon dioxide gas into a capillary micro-channel reactor containing ammonia water for absorption reaction to generate an ammonium carbonate intermediate solution, (2) respectively and continuously injecting the ammonium carbonate intermediate solution and an inorganic lithium salt solution into a continuous flow dynamic micro-reactor for precipitation reaction to obtain slurry containing lithium carbonate solids, and (3) carrying out solid-liquid separation, washing and drying on the slurry to obtain a battery grade lithium carbonate product.
  2. 2. The method for preparing battery grade lithium carbonate based on the continuous flow coupling micro-reaction system of claim 1, wherein the capillary micro-channel reactor has an inner diameter of 0.5-2.0 mm and a length of 1.2-20 m.
  3. 3. The method for preparing the battery-grade lithium carbonate based on the continuous flow coupling micro-reaction system according to claim 1, wherein in the step (1), gas-phase carbon dioxide and liquid-phase ammonia water are reacted in a micro-channel reactor, the flow rate of the carbon dioxide is 80-140 ml/min, the flow rate of the ammonia water is 1-15 ml/min, the molar concentration of the ammonia water is 0.5 mol/L-15 mol/L, and the molar ratio n (NH 3 ):n(CO 2 ) of the carbon dioxide gas and the ammonia in the ammonia water is 1.8:1 to 3.1:1.
  4. 4. The method for preparing battery grade lithium carbonate based on continuous flow coupling micro-reaction system according to claim 1, wherein in the step (1), the carbonate concentration in the intermediate solution at the outlet is 1.0-4.5 mol/L by adjusting the gas-liquid flow ratio.
  5. 5. The method for preparing battery grade lithium carbonate based on the continuous flow coupling micro-reaction system according to claim 1, wherein in the step (2), the inorganic lithium salt is lithium chloride, lithium sulfate or lithium nitrate, and the concentration of the inorganic lithium salt solution is 1.0-5.0 mol/L.
  6. 6. The method for preparing battery-grade lithium carbonate based on the continuous flow coupling micro-reaction system of claim 1, wherein a magnetic stirring device is arranged in the continuous flow dynamic micro-reactor, and the stirring rotation speed in the reaction process is controlled to be 500-1500 rpm.
  7. 7. The method for preparing the battery-grade lithium carbonate based on the continuous flow coupling micro-reaction system according to claim 1, wherein in the step (2), the inorganic lithium salt solution contains an antisolvent, the antisolvent is one or more of methanol, ethanol and isopropanol, and the volume ratio of the antisolvent in the inorganic lithium salt solution is 0-30%.
  8. 8. The method for preparing battery grade lithium carbonate based on the continuous flow coupling micro-reaction system according to claim 1, wherein in the step (2), the feeding molar ratio of the ammonium carbonate intermediate to the inorganic lithium salt n (CO 3 2- ): n (Li+) is 1:2 to 1.5:1.
  9. 9. The method for preparing battery grade lithium carbonate based on the continuous flow coupling micro-reaction system according to claim 1, wherein the reaction temperature in the step (2) is controlled to be 20-60 ℃, and the total residence time of materials in the continuous flow dynamic micro-reactor is 1-20 min.
  10. 10. The battery grade lithium carbonate prepared by the method according to any one of claims 1 to 9, wherein the battery grade lithium carbonate is in a uniform particle shape or a flake shape, the particle size D50 is 4 to 20 μm, and the content of Na, mg, ca and Fe is less than 0.001 wt%.

Description

Method for preparing battery-grade lithium carbonate based on continuous flow dynamic coupling micro-reaction system Technical Field The invention relates to the technical field of lithium battery material preparation and micro-chemical industry, in particular to a method for efficiently and continuously synthesizing battery-grade lithium carbonate by an ammonia process path through an anti-blocking microfluidic system. Background The battery grade lithium carbonate is used as a high added value lithium salt, and has extremely strict requirement on purity (> 99.5 wt%). At present, a precipitation method is mainly adopted in industry, and sodium carbonate is added into concentrated brine or ore leaching liquid to serve as a precipitant. However, since sodium ions (na+) and lithium ions (li+) have similar chemical properties, sodium impurity pollution is very easy to occur in the precipitation process, and multi-stage recrystallization purification is required, resulting in high production cost and complex process. In addition, in order to obtain a desired particle size distribution, high energy post-treatment techniques such as jet milling are generally employed. Microreactors exhibit significant advantages in the field of chemical synthesis due to their excellent mixing efficiency and mass and heat transfer properties. However, during the synthesis of lithium carbonate, the micro-channels are very prone to particle bridging, deposition and scaling, resulting in system blockage, which limits the application of microreaction technology in solid precipitation reactions. Thus, there is a need for a continuous flow synthesis process that can maintain high mixing efficiency in microreactors while effectively preventing solids plugging. With the rapid development of new energy automobiles and energy storage fields, high-purity battery grade lithium carbonate is used as a core raw material, and a high-efficiency and low-cost preparation technology of the high-purity battery grade lithium carbonate is focused on industry. The sodium salt precipitation method commonly adopted in the industry at present is very easy to introduce sodium impurities in the precipitation process because the chemical properties of sodium ions are similar to those of lithium ions, so that the purity of the product is difficult to directly reach the battery level standard, and the product is required to be subjected to complex repeated recrystallization purification, thereby greatly increasing the production energy consumption and the process cost. In contrast, the ammonia process technology for absorbing carbon dioxide (CO 2) by using ammonia water to generate an intermediate and reacting with lithium salt has the remarkable advantages that the route avoids the introduction of alkali metal ions from the source, remarkably improves the purity of the product, converts greenhouse gas carbon dioxide into high-added-value industrial lithium salt, meets the development targets of green chemical industry and carbon neutralization, and the reaction byproduct ammonium chloride can be recycled, thus having extremely high environmental protection value and economic benefit. However, the synthesis of lithium carbonate by the ammonia process is a complex reaction process, and precise control of the crystallization kinetics is critical to the particle size distribution of the product. Traditional kettle reactors tend to result in wider particle size distribution and uneven morphology of the product due to low mass transfer efficiency and uneven mixing. Although the micro-reaction technology can realize precise regulation and control of the crystallization process by virtue of excellent mass transfer performance and extremely high mixing efficiency, lithium carbonate is taken as a typical strong crystallization system, and crystal bridging and solid deposition are extremely easy to occur during separation in a micro-channel, so that serious system blockage is caused. Therefore, the research and development of the anti-blocking continuous flow dynamic microreactor which not only can exert the advantages of microscale mass transfer, but also can effectively prevent particles from gathering and hanging through dynamic mechanical shearing is a core technology for realizing continuous and large-scale production of battery-grade lithium carbonate. Disclosure of Invention Aiming at the defects of low purity, easy sodium pollution, complex process, easy blockage of a microreactor and the like in the lithium carbonate production in the prior art, the invention provides a method for preparing battery-grade lithium carbonate based on a continuous flow coupling microreaction system. Specifically, the continuous flow coupling micro-reaction system is formed by coupling a capillary micro-channel reactor with a continuous flow dynamic micro-reactor. According to one aspect of the invention, a method for preparing battery grade lithium carbonate based on a continuous flo