Search

CN-121292481-B - Process and device for preparing battery grade lithium carbonate based on mother liquor water concentrate

CN121292481BCN 121292481 BCN121292481 BCN 121292481BCN-121292481-B

Abstract

The application discloses a process and a device for preparing battery grade lithium carbonate based on a mother liquor water concentrated solution, and belongs to the technical field of lithium carbonate preparation. The process includes filtering mother liquid water, decarbonizing, concentrating, oxidizing low valence metal cation with oxidant to high valence state, settling, regulating pH value to eliminate metal cation impurity, ion exchange to obtain purified liquid, heat treatment of seed crystal with inert gas to repair surface defect of seed crystal, compounding seed crystal liquid, regulating spraying process, raising lithium depositing efficiency, reducing material loss, and final centrifugal washing, drying and crushing. The lithium deposition device comprises a lithium deposition kettle, an annular distributor and the like, and can realize efficient reaction. The application can directly prepare the high-purity battery grade lithium carbonate from the mother liquor water in one step, and has the advantages of short flow, low energy consumption, thorough impurity removal and excellent product performance.

Inventors

  • ZENG GUOFU
  • LIU TAOQING
  • SHANG YAWEI
  • LIU BIN

Assignees

  • 萍乡市拓源实业有限公司
  • 江西合一新材料科技有限公司

Dates

Publication Date
20260512
Application Date
20251107

Claims (7)

  1. 1. A process for preparing battery grade lithium carbonate based on a mother liquor water concentrate, which is characterized by comprising the following steps: S1, filtering, decarbonizing, concentrating, oxidizing and removing impurities from mother liquor water to obtain purified liquor, wherein in the step of removing impurities, the pH value of the mother liquor water is regulated and controlled in a sectional manner, a first part of sodium hydroxide is added into the mother liquor water, the mixture is uniformly stirred, the pH value is controlled to be 3.5-4, the temperature is 30-40 ℃ and the reaction is carried out for 1-2 hours, a second part of sodium hydroxide is added into the mother liquor water, the mixture is uniformly stirred, the pH value is controlled to be 5-6, the temperature is raised to 45-50 ℃, the reaction is carried out for 1.5-2 hours, and the mother liquor water after primary impurity removal is obtained through filtration; S2, carrying out heat treatment on the seed crystal in an inert gas/CO 2 mixed gas atmosphere, preserving heat for 4-5 hours to obtain a pretreated seed crystal, and preparing the pretreated seed crystal into seed crystal liquid, wherein the temperature of the heat treatment is 650-700 ℃; S3, adding the seed crystal liquid into a lithium precipitation kettle, and carrying out a lithium precipitation step, wherein the lithium precipitation step comprises the steps of adding a saturated sodium carbonate solution into the lithium precipitation kettle, adding a chelating agent under stirring, heating to 85-95 ℃, spraying a purifying liquid into the kettle, carrying out heat preservation and stirring after the lithium precipitation is finished, standing, and discharging supernatant after the precipitation is completed; S4, repeating the lithium precipitation step, and stopping the lithium precipitation step after the precipitated solid in the lithium precipitation kettle reaches the upper limit of the effective volume of the lithium precipitation kettle without discharging supernatant; S5, centrifuging all materials in the lithium precipitation kettle, stirring and washing lithium carbonate by using centrifugal water after the primary centrifugation is completed, performing secondary centrifugation after the stirring and washing is completed, performing secondary stirring and washing on the lithium carbonate by using deionized water after the secondary centrifugation is completed, and starting three times of centrifugation after the secondary stirring and washing is completed, so as to obtain a lithium carbonate primary material and the centrifugal water after the centrifugation is completed; S6, drying the primary lithium carbonate material, and crushing after drying, so as to obtain the battery grade lithium carbonate.
  2. 2. The process for preparing battery-grade lithium carbonate based on the mother liquor water concentrated solution according to claim 1, wherein the content of lithium in the concentrated mother liquor water in S1 is 7-9 g/L, and the oxidant adopted in the oxidation step comprises any one of hydrogen peroxide, ozone water and chlorine dioxide.
  3. 3. The process for preparing battery grade lithium carbonate based on the mother liquor water concentrated solution according to claim 1, wherein the oxidation step in S1 is that (0.01-0.1) mass part of oxidant is added into 100 mass parts of mother liquor water, the pH value of the mother liquor water is controlled to be 2-3, the temperature is 25-50 ℃, and the reaction is carried out for 0.5-2 hours after uniform stirring; The impurity removal step further comprises the steps of adding sodium carbonate into the mother liquor water subjected to primary impurity removal, stirring uniformly, heating to 60 ℃, reacting for 2-3 hours, filtering out solid impurities, and removing other impurity ions by using ion exchange resin to obtain purified liquor, wherein the mass ratio of the mother liquor water to the first sodium hydroxide to the second sodium hydroxide to the sodium carbonate in the impurity removal step is 100 (0.15-0.45) (0.09-0.3) (0.05-0.2).
  4. 4. A process for preparing battery grade lithium carbonate based on a mother liquor water concentrate according to claim 3, wherein the ion exchange resin comprises any one of a sulfonic acid group-or carboxylic acid group-containing lithium rejection type cation exchange resin.
  5. 5. The process for preparing the battery-grade lithium carbonate based on the mother liquor water concentrated solution is characterized in that the seed crystal in S2 is battery-grade lithium carbonate micro powder, the particle size distribution is that the median particle size D 50 is 3-8 mu m, the 90% cumulative particle size D 90 is not more than 15 mu m, the inert gas comprises any one of nitrogen, argon and helium, the ratio of CO 2 in the mixed gas is 0.5-1vol.%, the preparation method of the seed crystal liquid comprises the steps of pumping 10 parts by mass of saturated sodium carbonate solution into a seed crystal dispersion tank, adding (0.5-1) parts by mass of pretreated seed crystal into the dispersion tank, and starting a dispersing machine to disperse for 2-5 min at the speed of 2000-5000 rpm to obtain the seed crystal liquid.
  6. 6. The process for preparing battery grade lithium carbonate based on the mother liquor water concentrated solution according to claim 1, wherein the chelating agent in S3 comprises any one or more of ethylenediamine tetraacetic acid, diethylenetriamine pentaacetic acid, ethylenediamine tetrapropionic acid, hydroxyethylidene diphosphonic acid and aminotrimethylene phosphonic acid, and the mass ratio of the saturated sodium carbonate solution to the seed crystal solution to the chelating agent is 500 (3-5): 0.1-0.2.
  7. 7. The process for preparing battery grade lithium carbonate based on the mother liquor water concentrate according to claim 1, wherein the process for spraying the purifying liquid in S3 is a stage spraying, comprising: A1, setting the spraying flow to be 3-4 m 3 /h, stirring the mixture at the speed of 100-150 r/min, and spraying the mixture for 50-60 min; A2, setting the spraying flow to be 7-8 m 3 /h, stirring at a speed of 300-400 r/min, and spraying for 2-3 h; A3, setting the spraying flow to be 2-3 m 3 /h, stirring at the rotation speed of 80-100 r/min, sampling mother liquor in the kettle to detect the concentration of carbonate, and ending lithium precipitation when the concentration of carbonate is reduced to 14-17 g/L.

Description

Process and device for preparing battery grade lithium carbonate based on mother liquor water concentrate Technical Field The application relates to the technical field of lithium carbonate preparation, in particular to a process and a device for preparing battery-grade lithium carbonate based on a mother liquor water concentrate. Background In recent years, with the great development of new energy industry, the demand of lithium ion batteries is greatly increased, and the purity of battery-grade lithium carbonate serving as a core raw material of lithium ion batteries directly influences the performance and application effect of the lithium ion batteries. In the prior art, in the process of preparing battery grade lithium carbonate by using lithium sulfate and sodium carbonate to react, a great amount of mother liquor water is generated in a primary lithium precipitation process, and a great amount of lithium ions are contained in the mother liquor water, and meanwhile, the mother liquor water contains high-concentration sodium, potassium, sulfate radicals, calcium and other impurity ions. In order to recover lithium in the mother liquor, the prior art generally carries out decarbonization, evaporation concentration treatment and secondary lithium precipitation on the mother liquor. However, because the impurity components in the mother liquor are complex and the content is high, the purity of the lithium carbonate product obtained by secondary lithium precipitation can only reach the industrial level standard, and if the battery level requirement is met, the purification procedures such as dissolution, impurity removal, recrystallization and the like are needed to be carried out for many times. The process has the problems of long flow, large equipment investment, high energy consumption, large reagent consumption and the like, not only increases the production cost, but also causes low production efficiency, and is difficult to adapt to the production requirements of large-scale and low-cost battery-grade lithium carbonate. In addition, in the traditional secondary lithium deposition process, the removal of impurity ions is incomplete, the lithium deposition reaction conditions are controlled roughly, the purity of the generated lithium carbonate crystal is insufficient, the particle size distribution is uneven, and the subsequent purification difficulty is further increased. The Chinese patent of the invention with the publication number of CN112142080A provides a method for preparing battery grade lithium carbonate by freezing and recycling precipitated lithium concentrated mother liquor. However, in the process of preparing battery-grade lithium carbonate by recovering mother liquor in the prior art, the problems of low lithium ion utilization rate, high impurity content of the prepared battery-grade lithium carbonate, poor practical application effect and the like exist. Therefore, development of a simplified process capable of directly preparing battery-grade lithium carbonate from a mother liquor water concentrated solution in one step, and realization of short-flow, low-energy consumption and high-purity production become technical problems to be solved in the field. Disclosure of Invention Aiming at the defects of the prior art, the application provides a process and a device for preparing battery grade lithium carbonate based on a mother liquor water concentrated solution, which effectively remove metal cation impurities in the mother liquor water by using an oxidant and a method for adjusting pH sedimentation impurities in a sectional manner, then perform heat treatment on seed crystals to improve the adsorptivity of the seed crystals to Li +, then add the seed crystal solution, saturated sodium carbonate solution and purifying solution into a lithium precipitation kettle for reaction, and finally obtain the battery grade lithium carbonate with high purity through centrifugal washing, drying and crushing by adopting a sectional spraying process to save reaction raw materials of the purifying solution. In order to achieve the above purpose, the present application provides the following technical scheme: In a first aspect, the application provides a process for preparing battery grade lithium carbonate based on a mother liquor water concentrate, comprising the steps of: S1, filtering, decarbonizing, concentrating, oxidizing and removing impurities from mother liquor water to obtain a purified liquor; S2, carrying out heat treatment on the seed crystal in an inert gas/CO 2 mixed gas atmosphere, preserving heat for 4-5 hours to obtain a pretreated seed crystal, and preparing the pretreated seed crystal into seed crystal liquid; the step can effectively repair the defects on the surface of the seed crystal, form a stable crystal face structure and improve the adsorption effect on Li +. S3, adding the seed crystal liquid and the saturated sodium carbonate solution into a lithium precipitation kettle