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CN-116654959-B - Method for producing battery-grade lithium carbonate by gas-liquid circulation

CN116654959BCN 116654959 BCN116654959 BCN 116654959BCN-116654959-B

Abstract

The invention provides a method for producing battery grade lithium carbonate by gas-liquid circulation, which comprises the steps of preparing industrial grade lithium carbonate, water and quicklime into slurry for causticizing reaction, refining and carbonizing an obtained lithium hydroxide solution to obtain battery grade lithium carbide and carbonized liquid, concentrating and crystallizing the carbonized liquid by primary evaporation to recover part of lithium carbonate, adding acid into the primary concentrated liquid obtained by crystallization to adjust the pH value so as to convert lithium salt into soluble lithium salt, then carrying out secondary evaporation and concentration crystallization, discharging most sodium potassium salt in the system to obtain secondary concentrated liquid, precipitating lithium by sodium carbonate from the secondary concentrated liquid, further recovering lithium carbonate from the obtained precipitated lithium solution, discharging sodium potassium salt by crystallization, and obtaining the crystallized liquid capable of being recycled. The production method has the advantages of low cost, less medicament use, good quality of the obtained lithium carbonate product, high recovery rate, environment friendliness, short process and considerable industrial application prospect, and the whole process realizes the recycling of carbon dioxide and liquid.

Inventors

  • HU QIYANG
  • WANG JIEXI
  • JIA GUIBIN
  • LIU SONGLIN
  • SONG XIAOPENG
  • HU ZEXIANG

Assignees

  • 江西云威新材料有限公司
  • 九江云威锂业有限公司

Dates

Publication Date
20260508
Application Date
20230710

Claims (10)

  1. 1. A method for producing battery grade lithium carbonate by gas-liquid circulation, which is characterized by comprising the following steps: (1) Preparing industrial grade lithium carbonate, water and quicklime into slurry for causticizing reaction, and carrying out solid-liquid separation to obtain lithium hydroxide solution and causticizing slag; (2) Evaporating and concentrating the lithium hydroxide solution, cooling and crystallizing, redissolving and precisely filtering the obtained crystal to obtain a lithium hydroxide refined solution; (3) Introducing carbon dioxide into the lithium hydroxide refined solution to carry out carbonization reaction, and carrying out solid-liquid separation after carbonization to obtain battery-grade lithium carbonate and carbonized solution; (4) Performing first evaporation concentration and cooling crystallization on the carbonized liquid, and filtering to obtain lithium carbonate and primary concentrated liquid, wherein the first evaporation concentration ratio is 2-3:1, and the cooling crystallization temperature after the first evaporation concentration is 20-40 ℃; Adding acid into the primary concentrated solution to adjust the pH value to 5-7, then carrying out second evaporation concentration and cooling crystallization, and filtering to obtain sodium potassium salt and secondary concentrated solution, wherein the cooling crystallization temperature after the second evaporation concentration is 20-40 ℃; Adding sodium carbonate into the secondary concentrated solution to precipitate lithium to obtain lithium carbonate and a solution after precipitation of lithium, crystallizing and carrying out solid-liquid separation on the solution after precipitation of lithium to obtain sodium potassium salt and a solution after crystallization, wherein the lithium content of the sodium potassium salt is less than 0.3wt.%, and in the step (4), the solution after crystallization is returned to the step (1) to prepare slurry or is combined with the solution after carbonization for treatment.
  2. 2. The method for producing battery grade lithium carbonate by gas-liquid circulation according to claim 1, wherein in the step (1), the content of Li 2 CO 3 in the industrial lithium carbonate is not less than 98.5wt.% and the CaO content of the quicklime is not less than 90wt.%; The Li content of the obtained lithium hydroxide solution is 8.5-9.5 g/L.
  3. 3. The method for producing battery grade lithium carbonate by gas-liquid circulation according to claim 1, wherein in the step (1), the molar ratio of Li 2 CO 3 to CaO in the slurry is 1:1.05-1.5, and the solid-liquid ratio is 1:8-12; the temperature of the causticizing reaction is 80-95 ℃, the stirring speed is 200-400 rpm, and the time of the causticizing reaction is 1-10 h.
  4. 4. The method for producing battery-grade lithium carbonate by gas-liquid circulation according to claim 1, wherein in the step (2), the vapor temperature of the evaporation concentration is 100-120 ℃, and the temperature of the cooling crystallization is 40-50 ℃; The Li content of the lithium hydroxide solution is 25-35 g/L, and the Li content of the obtained lithium hydroxide refined solution is 25-35 g/L.
  5. 5. The method for producing battery-grade lithium carbonate by gas-liquid circulation according to claim 1, wherein in the step (3), the carbon dioxide is industrial-grade carbon dioxide, the temperature of the carbonization reaction is 20-80 ℃, and the final pH value of the carbonization reaction is 9.5-10.5; the Li content of the carbonized liquid is 2-6 g/L.
  6. 6. The method for producing battery grade lithium carbonate by gas-liquid circulation according to claim 1, wherein in the step (4), the temperature of the first evaporation concentration is 100-120 ℃; The temperature of the second evaporation concentration is 100-120 ℃, and the second evaporation concentration ratio is 2-5:1; The acid is sulfuric acid or hydrochloric acid, and the carbon dioxide generated by regulating the pH value is collected and concentrated and then returned to the step (3) for carbonization reaction.
  7. 7. The method for producing battery-grade lithium carbonate by gas-liquid circulation according to claim 1, wherein in the step (4), the addition amount of sodium carbonate is 1.05-1.1 times of the theoretical amount required for realizing complete lithium precipitation of the secondary concentrated solution; in the step (4), the lithium carbonate obtained by cooling crystallization and lithium precipitation of sodium carbonate is returned to the step (1) for replacing at least part of industrial lithium carbonate.
  8. 8. The method for producing battery grade lithium carbonate by gas-liquid circulation according to claim 1, wherein in the step (1), the causticized slag is calcined at high temperature to obtain regenerated quicklime and carbon dioxide; And (3) the concentrated carbon dioxide is used for carbonization reaction in the step (3), the regenerated quicklime returns to the step (1) to be used as a raw material when the CaO content in the regenerated quicklime is more than or equal to 90wt.%, and the regenerated quicklime is sold when the CaO content in the regenerated quicklime is less than 90 wt.%.
  9. 9. The method for producing battery grade lithium carbonate by gas-liquid circulation according to claim 8, wherein before high temperature calcination, the causticized slag is washed with water to obtain washing slag for high temperature calcination of regenerated quicklime and washing water, and the washing water is returned to step (1) for preparing slurry.
  10. 10. The method for producing battery grade lithium carbonate by gas-liquid circulation according to claim 1, wherein in the step (4), the lithium content in the lithium carbonate obtained by cooling crystallization and lithium precipitation of sodium carbonate is 17-18.7%.

Description

Method for producing battery-grade lithium carbonate by gas-liquid circulation Technical Field The invention belongs to the technical field of production of battery-grade lithium carbonate, and particularly relates to a method for producing battery-grade lithium carbonate by gas-liquid circulation. Background Lithium and related industries are new forces in the 21 st century energy industry, and lithium has unique properties of high conductivity and high chemical electrochemical activity, and is called "energy metal" and "important element for promoting the world to advance". Lithium carbonate is a basic industrial product of lithium, is widely applied to the fields of lithium ion batteries, medicines, military aviation and the like, is a raw material for preparing other lithium salts, is also a raw material necessary for new energy battery materials such as lithium iron phosphate, lithium hexafluorophosphate and the like, and is rapidly increased in demand along with rapid development of new energy automobiles. The battery grade lithium carbonate has strict requirements on the purity and impurities of the product, and is usually prepared by taking industrial grade lithium carbonate as a raw material. The current industrial methods for producing battery grade lithium carbonate by using industrial grade lithium carbonate as a raw material comprise a hydro-pyrolysis method, a bipolar membrane carbonization method and a causticizing carbonization method. The Chinese patent document CN115286017A discloses a preparation method of battery grade lithium carbonate, which utilizes carbonization and hydrogenation reaction of carbon dioxide and crude lithium carbonate solution to obtain lithium bicarbonate solution, and then heats the lithium bicarbonate solution to obtain the battery grade lithium carbonate, however, the pyrolysis process of the technology is not easy to control, the lithium loss is large, and the prepared battery grade lithium carbonate is easy to agglomerate and does not have cost advantage. The Chinese patent document CN107298450B discloses a method for preparing lithium hydroxide and lithium carbonate by using a soluble lithium salt solution, wherein the method uses a bipolar membrane electrodialyzer to carry out bipolar membrane electrolysis on the soluble lithium salt solution, a lithium hydroxide solution is obtained at a cathode, and then high-purity lithium carbonate is obtained through carbonization. Chinese patent document CN115340109a discloses a method for preparing high purity lithium carbonate by using crude lithium carbonate, in which a lithium hydroxide solution is obtained by causticizing reaction of calcium hydroxide and crude lithium carbonate, and then high purity lithium carbonate is obtained by carbonization, the method does not consider treatment of calcium slag and mother liquor after carbonization, which causes lithium loss, and carbonized mother liquor does not undergo treatment to enter circulation, which is easy to cause accumulation of impurity ions, and finally affects product quality. The lithium precipitation mother liquor generally contains higher lithium ion concentration and has recovery value. The existing lithium precipitation mother liquor treatment technology mainly comprises freezing crystallization, evaporation concentration, extraction, adsorption method and the like. The extraction and adsorption method is a technology for selectively extracting lithium from lithium-precipitating mother liquor by utilizing a lithium extractant and a lithium ion sieve, and has high selectivity to lithium, however, the recycling difficulty of the extractant and the ion sieve is high, the investment cost is high, and the industrialized development is hindered. Freezing crystallization and evaporative concentration are early recycling technology for lithium carbonate mother liquor, and are relatively mature in application. However, the technical barrier of freeze crystallization is relatively high, the reaction speed is lower than that of high-temperature evaporation crystallization reaction, and the granularity and morphology of the product are difficult to control. Chinese patent document CN106882822A discloses a method for recovering lithium from lithium precipitation mother liquor into battery grade lithium carbonate, the method aims at carrying out freezing and salting out to precipitate sodium sulfate aiming at the lithium precipitation mother liquor of sodium carbonate and lithium sulfate reaction, CN110451536A discloses a method for recovering lithium from the battery grade lithium carbonate mother liquor, and the sodium sulfate and the battery grade lithium carbonate are prepared by adopting a freezing crystallization and evaporation concentration synergistic process, so that the lithium yield is lower. Chinese patent document CN104925837A discloses a method for preparing lithium salt by recovering battery-grade lithium carbonate precipitation mother liquor, which util