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CN-117699828-B - Purification method of lithium carbonate

CN117699828BCN 117699828 BCN117699828 BCN 117699828BCN-117699828-B

Abstract

The invention discloses a purification method of lithium carbonate, which comprises the steps of mixing industrial grade lithium carbonate and water according to a certain proportion, stirring and pulping, introducing carbon dioxide into the pulped solution under the stirring condition for reaction to obtain a lithium bicarbonate solution, dropwise adding barium hydroxide into the lithium bicarbonate solution after the reaction is finished, then filtering, dropwise adding a small amount of hydrofluoric acid into the obtained filtrate, then filtering, and obtaining a purer lithium bicarbonate solution through a cation exchange column. And (3) carrying out pyrolysis crystallization on the obtained lithium bicarbonate filtrate, filtering to obtain lithium carbonate crystals, adding a certain amount of ultrapure water into the obtained lithium carbonate crystals, stirring, filtering, and washing to obtain the high-purity lithium carbonate. The invention can obtain high-purity lithium carbonate with purity more than or equal to 99.99 percent, the addition amount of hydrofluoric acid in the process is less, the aim of removing impurities can be achieved, and the influence on the product yield is reduced as much as possible.

Inventors

  • YUE JINYU
  • GUI GANG
  • LIU CHANG
  • ZHENG LEI
  • GAO LIHONG
  • DONG MENGYUAN
  • ZENG YUQIN
  • LIU JIAXIN
  • ZHAN ZHIHUI

Assignees

  • 宜都兴发化工有限公司

Dates

Publication Date
20260508
Application Date
20231217

Claims (9)

  1. 1. A method for purifying lithium carbonate, comprising: (1) Mixing industrial lithium carbonate with water, stirring and pulping; (2) Dropwise adding barium hydroxide into the lithium bicarbonate solution A to remove magnesium ions and sulfate ions, and filtering after the reaction is finished to obtain a lithium bicarbonate solution B; (4) Dripping trace hydrofluoric acid into the filtrate B to remove calcium ions, and filtering after the reaction is finished to obtain filtrate C; (5) The filtrate C is subjected to a chromatographic column to obtain filtrate D, wherein the ion exchange resin used by the chromatographic column is mixed resin formed by LSC-500 resin, D451 resin and S930 resin according to the mass ratio of 2-4:4-8:1-3; (6) Heating and crystallizing the filtrate D, and filtering to obtain solid lithium carbonate and filtrate E; (7) And drying the solid lithium carbonate to obtain lithium carbonate.
  2. 2. The method for purifying lithium carbonate according to claim 1, wherein the beating operation in the step (1) comprises the steps of (1) mixing industrial grade lithium carbonate with high purity water at a ratio of (5-25) and a stirring speed of 200-600r/min, wherein the purity of the industrial lithium carbonate is in the range of 98.5-99.4%, and the conductivity of ultrapure water is less than or equal to 0.2us/cm.
  3. 3. The method for purifying lithium carbonate according to claim 1, wherein the stirring speed in the step (2) is 200 to 500r/min, the reaction temperature is controlled to be 0 to 20 ℃, the gas flow rate of carbon dioxide is 0.2 to 10.0L/min, and the aeration time of carbon dioxide is 1 to 6 hours.
  4. 4. The method for purifying lithium carbonate according to claim 1, wherein the amount of the barium hydroxide added in the step (3) is 0.05 g/L to 2.0 g/L in a lithium bicarbonate solution, the reaction temperature is 0 to 25 ℃, the reaction time after adding the barium hydroxide is 20 to 120min, and the purity of the barium hydroxide is 99.9%.
  5. 5. The method for purifying lithium carbonate according to claim 1, wherein the mass ratio of the added amount of hydrofluoric acid to the raw material lithium carbonate in the step (4) is 1 (10-100), the mass concentration of hydrofluoric acid is 40-49%, the reaction temperature is 0-25 ℃, and the reaction time after adding hydrofluoric acid dropwise is 10-60min.
  6. 6. The method for purifying lithium carbonate according to claim 1, wherein the resin is packed in a column having a diameter of 2.0 to 2.5cm and a height of 30 to 40cm, an aspect ratio of 16:1, and the resin is flowed through the column at a flow rate of 0.4 to 2.0L/h.
  7. 7. The method for purifying lithium carbonate according to claim 1, wherein the reaction temperature in the step (6) is 70 to 100 ℃ and the reaction time is 0.5 to 4 hours.
  8. 8. The method for purifying lithium carbonate according to claim 1, wherein the mixing ratio of the lithium carbonate to water in the step (7) is 1 (3-10), the stirring rate after mixing is 200-500r/min, the stirring time is 30-120min, and the beating washing temperature is 50-90 ℃.
  9. 9. The method for purifying lithium carbonate according to claim 1, wherein the filtering membrane used in the steps (3), (4), (6) and (7) is a nitrocellulose acetate filtering membrane with a pore diameter of less than or equal to 5 μm, and the drying temperature of the lithium carbonate obtained after the filtering in the step (7) is 70-150 ℃ and the drying time is 8-15h.

Description

Purification method of lithium carbonate Technical Field The invention belongs to the technical field of lithium carbonate purification, and particularly relates to a technical process for preparing high-purity lithium carbonate by purifying industrial-grade lithium carbonate. Background The lithium carbonate is used as an upstream product in the lithium industry, has very wide application, and can be used as a raw material to prepare various lithium industrial products, so that the lithium carbonate is also a compound which is not substitutable in the lithium salt industry due to the unique position and property. The Chinese lithium resources are rich, but the purity is relatively low, the application of the current high-purity lithium salt in the high and new technical fields such as new energy sources, new materials and the like is continuously expanded, the application of the high-purity lithium salt in the lithium battery industry is particularly prominent, the variety of the product is continuously promoted to be new, the yield is gradually increased year by year, and the lithium also shows the importance of energy metals. On the other hand, along with the high-speed development of industries such as electrochemistry, new energy automobiles and the like, the application of the high-purity lithium carbonate in industry is wider, for example, the high-purity lithium carbonate can be used for synthesizing lithium electrolyte salts such as lithium bis (fluorosulfonyl) imide, lithium bis (trifluoromethylsulfonyl) imide, lithium tetrafluoroborate and the like, and the lithium salts have higher requirements on the quality of lithium carbonate products, so that the development of the high-purity lithium carbonate (99.9-99.99%) from industrial grade lithium carbonate (98.5-99.4%) as a raw material has great industrial application prospect. Most of the prior art is to purify industrial lithium carbonate to battery grade lithium carbonate, sodium ion and potassium ion content in the battery grade lithium carbonate obtained by purification is high, and is difficult to meet the production requirements of lithium salts such as lithium bis (fluorosulfonyl) imide, and in order to remove more calcium ion and magnesium ion in the industrial lithium carbonate, hydrofluoric acid, barium hydroxide and barium bicarbonate are generally introduced as precipitants to remove divalent impurity ions, but excessive hydrofluoric acid and barium salt are very easy to introduce fluorine ion and barium ion to generate new impurities which are difficult to remove. Part of the patents can prepare the industrial lithium carbonate into high-purity lithium carbonate, but the high-purity lithium carbonate can be repeatedly subjected to ion exchange resin and repeated washing, so that the yield of the lithium carbonate is obviously reduced, the washing filtrate and the pyrolysis and crystallization filtrate are combined to be used as mother liquor, and the mother liquor and the raw material lithium carbonate are prepared into slurry, so that the lithium carbonate dissolved in the mother liquor is recycled, and the loss of the lithium carbonate is reduced. Therefore, the method does not completely depend on adding the precipitant to remove impurity metal ions, but combines adding a small amount of precipitant barium hydroxide and hydrofluoric acid to remove impurity bivalent impurity ions with ion exchange resin, so that the introduction of new impurity ions is reduced, the yield loss caused by the times of filtrate passing through the ion exchange column is relatively reduced, and the method has important significance for industrial production. Disclosure of Invention Aiming at the defects of the prior art, the invention provides a method for purifying industrial lithium carbonate to high-purity lithium carbonate, which has the following technical scheme: The purification method of the high-purity lithium carbonate comprises the following steps: (1) Mixing industrial lithium carbonate with water, stirring and pulping; (2) Under the condition of stirring, carbon dioxide with a certain air flow is introduced into the pulping solution at a controlled temperature for reaction, and lithium bicarbonate solution A is obtained after a certain time of reaction; (3) Adding a proper amount of barium hydroxide into the lithium bicarbonate solution according to the content of sulfate radical in the raw material industrial lithium carbonate obtained by testing, removing magnesium ions and sulfate radical, reacting for 20-120min, wherein the purity of the barium hydroxide is 99.9%, and filtering after the reaction is finished to obtain filtrate B; (4) Dropwise adding a small amount of hydrofluoric acid solution into the filtrate B, stirring for 10-60min, and filtering to obtain filtrate C; (5) And (3) allowing the obtained filtrate C to flow through a chromatographic column, and repeatedly flowing through the chromatographic column for several times to ob