Method for recovering valuable metal from waste lithium iron phosphate positive electrode material

Abstract

The invention provides a method for recycling valuable metals from a waste lithium iron phosphate positive electrode material, and belongs to the technical field of resource recycling, water is added into the waste lithium iron phosphate positive electrode material to prepare slurry, then acid liquor and an oxidizing agent are added into the slurry, lithium can be selectively leached by utilizing an acid leaching method in combination with the effect of the oxidizing agent, and the valuable metals are recycled. The separation of lithium and iron is realized, and the lithium leaching rate and leaching selectivity are relatively high; drying the first filter residue containing iron, preparing a reducing agent, and performing high-temperature reduction treatment to obtain yellow phosphorus and ferrophosphorus; a first lixivium containing lithium is sequentially subjected to filtering impurity removal, evaporation concentration and lithium precipitation treatment to obtain crude lithium carbonate, and finally pure lithium carbonate is obtained through purification treatment such as purification, evaporation and crystallization. Compared with the existing traditional process, the process flow is simplified, and the consumption of acid and alkali is reduced, so that the recovery cost is reduced, zero secondary waste can be generated, and secondary pollution is avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of resource recycling, more specifically, to a method for recovering valuable metals from waste lithium iron phosphate positive materials. BACKGROUND

[0002] With the large-scale application of LiFePO4 materials in the field of new energy vehicles, a large number of waste LiFePO4 batteries will be generated after the retirement of power batteries. If these waste LiFePO4 batteries are not disposed of in time, not only a large amount of metal resources will be wasted, but also the environment will be polluted, and even human health will be endangered. Therefore, how to dispose of waste LiFePO4 batteries in a harmless manner and realize green and environmentally friendly recycling of waste LiFePO4 batteries has become a problem that must be faced.

[0003] Based on the above problems, one of the current solutions is to repair and regenerate qualified lithium iron phosphate positive materials by adding lithium sources and carbon sources. For example, patents CN102208706A, CN113582153A, CN113086961A, CN116315229A, etc. This solution of regenerating lithium iron phosphate positive materials can make waste LiFePO4 batteries be reused and has the advantage of good economic benefit. However, after thousands of charge and discharge cycles, the structure of LiFePO4 positive materials has been destroyed, and even after repair and regeneration treatment, the electrochemical performance of the materials is still difficult to completely recover. Moreover, in the case of large-scale treatment of LiFePO4 waste, high-temperature solid-phase repair is difficult to ensure the uniformity of lithium supplementation and is also difficult to control the morphology and crystallinity of the particles. In addition, the electrochemical performance of regenerated LiFePO4 is greatly affected by impurities, and in order to obtain a regenerated material with good performance, the impurities in the material to be repaired need to be strictly controlled during the repair and regeneration process, which requires more stringent process requirements.

[0004] Another current solution is to recover lithium from waste lithium iron phosphate materials to avoid waste of metal resources. For example, patents CN116553502A, CN105024106A, CN113603119A, etc. However, the current methods for recovering valuable metals from waste lithium iron phosphate positive materials generally have problems such as long recovery process, secondary pollution, relatively low product purity or performance, etc.

[0005] Therefore, it is of great significance to seek reasonable ways and process conditions to recycle and utilize waste LiFePO4 batteries, minimize the impact of harmful substances in waste LiFePO4 batteries on the environment and human health, and generate certain economic benefits.

[0006] It should be noted that the information disclosed in the above Background section is only used to strengthen the understanding of the background of the present application, and therefore can include information that does not constitute prior art known to those of ordinary skill in the art. SUMMARY

[0007] In view of the above problems, the purpose of the present application is to provide a method for recovering valuable metals from waste lithium iron phosphate positive electrode materials, so as to solve the problems of long recovery process, secondary pollution, relatively low product purity or performance, etc. in the prior art method for recovering valuable metals from waste lithium iron phosphate positive electrode materials.

[0008] The present application provides a method for recovering valuable metals from waste lithium iron phosphate positive electrode materials, comprising the following steps:

[0009] Water is added to the waste lithium iron phosphate positive electrode material to prepare a slurry;

[0010] An acid solution and an oxidizing agent are added to the slurry, and after reacting for a first preset time, the slurry is filtered to obtain a leaching solution and a first filter residue;

[0011] After the first leaching solution is filtered to remove impurities, a filtrate and a second filter residue are obtained; and after the first filter residue is dried, it is dosed with a reducing agent in a preset proportion, and the mixture obtained by dosing is put into a vacuum smelting furnace for high-temperature reduction to obtain yellow phosphorus and phosphorus iron;

[0012] The filtrate is subjected to evaporation and concentration treatment to obtain a concentrated solution;

[0013] A lithium sink is added to the concentrated solution, and after reacting for a second preset time, a crude lithium carbonate is obtained;

[0014] After the crude lithium carbonate is sequentially subjected to purification, evaporation and crystallization treatment, pure lithium carbonate is obtained.

[0015] In addition, in the process of preparing the slurry by adding water to the waste lithium iron phosphate positive electrode material, the mass-volume ratio of the waste lithium iron phosphate positive electrode material to water is preferably 1:2-1:10.

[0016] In addition, the acid solution is preferably any one of sulfuric acid, phosphoric acid, nitric acid, or at least two mixed in any proportion; and / or the volume ratio of the acid solution to the slurry is 1:1-1:5.

[0017] In addition, the oxidizing agent is preferably any one of hydrogen peroxide, hypochlorite, oxygen, or at least two mixed in any proportion; and / or the volume ratio of the oxidizing agent to the slurry is 1:1-1.2:1.

[0018] In addition, preferably, the first preset time is 1-3 hours.

[0019] In addition, preferably, the reducing agent is any one of coke, pulverized coal, carbon monoxide, or at least two mixed in any proportion; and / or, the molar ratio of the first filter residue after drying to the reducing agent is 2.5:1.

[0020] In addition, preferably, the reduction temperature of the mixed material in the vacuum melting furnace is 1300-1500℃; and the high-temperature reduction time is 0.5-2 hours.

[0021] In addition, preferably, in the process of evaporating and concentrating the filtrate to obtain the concentrated liquid, the concentration multiple of the evaporating and concentrating process is 10-30.

[0022] In addition, preferably, the lithium precipitating agent is any one of sodium carbonate, carbon dioxide, sodium bicarbonate, or at least two mixed in any proportion; and / or,

[0023] The concentration of the lithium precipitating agent is 300-350 g / L; and / or,

[0024] The stoichiometric ratio of the lithium precipitating agent to lithium ions in the concentrated liquid is 20:11-5:3; and / or,

[0025] The second preset time is 1-2 hours.

[0026] In addition, preferably, in the process of obtaining the pure lithium carbonate by sequentially purifying, evaporating, and crystallizing the crude lithium carbonate,

[0027] The purification process uses a liquid-solid ratio of 10:1-20:1 of pure water to crude lithium carbonate, and 1-3 L / min of carbon dioxide to purify the crude lithium carbonate;

[0028] The evaporation temperature is 80-100℃; and the evaporation time is 1-10 hours;

[0029] The crystallization temperature is 25-30℃; and the crystallization time is 2-5 hours.

[0030] From the above technical solutions can be known, the method for recovering valuable metals from waste old lithium iron phosphate positive material provided by the application, by adding water to the waste old lithium iron phosphate positive material, a slurry is prepared, then acid liquor and oxidizing agent are added to the slurry, lithium can be selectively leached by the acid leaching method combined with the action of the oxidizing agent, the separation of lithium and iron is realized, and the lithium leaching rate and leaching selectivity are relatively high; then the first filter residue containing iron is subjected to drying, reducing agent batching and high-temperature reduction treatment, yellow phosphorus and phosphorus iron are obtained; the first leaching solution containing lithium is subjected to impurity removal by filtration, evaporation concentration and lithium precipitation treatment in sequence, and then the crude lithium carbonate is obtained, and finally, the pure lithium carbonate is obtained through purification, evaporation and crystallization; compared with the current existing traditional process, the process flow is simplified, the amount of acid and alkali is reduced, the recovery cost is reduced, zero secondary waste generation can be achieved, secondary pollution can be avoided, lithium and phosphorus in the waste old lithium iron phosphate positive material battery can be simultaneously recovered, and the method has strong market competitiveness and application value.

[0031] To the accomplishment of the foregoing and related ends, the application, or one or more aspects thereof, include the features hereinafter fully described and illustrated in the accompanying drawings. These aspects are indicative, however, of but a few of the various ways in which the principles of the application can be employed. Other objects, advantages, and novel features of the application will become apparent from the following detailed description when considered in conjunction with the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0032] Other objects and results of the application will become more fully understood and appreciated only by referring to the following description taken in conjunction with the accompanying drawings.

[0033] Figure 1 Flow chart of the method for recovering valuable metals from waste old lithium iron phosphate positive material according to the embodiment of the application. DETAILED DESCRIPTION

[0034] In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more embodiments. It can be evident, however, that the embodiments can be practiced without these specific details.

[0035] In view of the foregoing, the method for recovering valuable metals from waste old lithium iron phosphate positive material in the prior art has the problems of long recovery process, secondary pollution, relatively low product purity or performance, etc., and a method for recovering valuable metals from waste old lithium iron phosphate positive material is proposed.

[0036] The specific embodiments of the application will be described below in detail with reference to the accompanying drawings.

[0037] In order to illustrate the method for recovering valuable metals from waste old lithium iron phosphate positive material provided by the application,Figure 1 A flowchart of a method for recovering valuable metals from waste lithium iron phosphate positive electrode material according to an embodiment of the present application is shown.

[0038] The present application provides a method for recovering valuable metals from waste lithium iron phosphate positive electrode material, comprising the following steps:

[0039] Step S1, water is added to the waste lithium iron phosphate positive electrode material to prepare a slurry.

[0040] Specifically, in order to facilitate the preparation of the slurry, the waste lithium iron phosphate positive electrode material is generally pretreated into a powder material, and the particle size of the powder material can be determined according to actual conditions.

[0041] As a preferred embodiment of the present application, during the preparation of the slurry by adding water to the waste lithium iron phosphate positive electrode material, the mass-volume ratio of the waste lithium iron phosphate positive electrode material to water is 1:2-1:10.

[0042] The mass-volume ratio refers to the proportional relationship between the mass of the waste lithium iron phosphate positive electrode material and the volume of water, for example, when the mass-volume ratio of the waste lithium iron phosphate positive electrode material to water is 1:2, it means that 1g of waste lithium iron phosphate positive electrode powder is added to 2ml of water.

[0043] Step S2, acid and oxidizing agent are added to the slurry, and after reacting for a first preset time, the slurry is filtered to obtain a leaching solution and a first filter residue.

[0044] Specifically, after adding acid and oxidizing agent to the slurry, lithium can be selectively leached from the waste lithium iron phosphate positive electrode material under the action of the acid and the oxidizing agent, thereby realizing the separation of lithium and iron, and having a high lithium leaching rate and leaching selectivity. The leaching solution contains lithium; the first filter residue contains iron and phosphorus.

[0045] As a preferred embodiment of the present application, the acid is any one of sulfuric acid, phosphoric acid, nitric acid, or at least two mixed in any proportion; and / or, the volume ratio of the acid to the slurry is 1:1-1:5.

[0046] As a preferred embodiment of the present application, the oxidizing agent is any one of hydrogen peroxide, hypochlorite, oxygen, or at least two mixed in any proportion; and / or, the volume ratio of the oxidizing agent to the slurry is 1:1-1.2:1.

[0047] As a preferred embodiment of the present application, the first preset time is 1-3h.

[0048] It should be noted that in the technical solution of the present application, the types of the above-mentioned acid and oxidizing agent are preferred embodiments, but are not limited thereto; the amount of acid, the amount of oxidizing agent, and the specific setting of the first preset time can be selected according to actual needs, and the present application does not make special limitations thereon.

[0049] Step S3, after the first leaching liquid is filtered to remove impurities, a filtrate and a second filter residue are obtained; and after the first filter residue is dried, the first filter residue is mixed with a reducing agent at a preset ratio, and the mixture obtained by the mixing is put into a vacuum smelting furnace for high-temperature reduction to obtain yellow phosphorus and phosphorus iron.

[0050] As a preferred scheme of the present application, the reducing agent is any one of coke, pulverized coal, carbon monoxide or at least two mixed in any ratio; and / or, the molar ratio of the dried first filter residue to the reducing agent is 2.5:1.

[0051] As a preferred scheme of the present application, the reduction temperature of the mixture in the vacuum smelting furnace is 1300-1500°C; and the high-temperature reduction time is 0.5-2h.

[0052] Step S4, the filtrate is subjected to evaporation concentration treatment to obtain a concentrated liquid.

[0053] As a preferred scheme of the present application, in the process of subjecting the filtrate to evaporation concentration treatment to obtain a concentrated liquid, the concentration multiple of the evaporation concentration treatment is 10-30.

[0054] Step S5, a lithium precipitation agent is added to the concentrated liquid, and after reacting for a second preset time, a crude lithium carbonate is obtained.

[0055] As a preferred scheme of the present application, the lithium precipitation agent is any one of sodium carbonate, carbon dioxide, sodium bicarbonate or at least two mixed in any ratio; and / or,

[0056] The concentration of the lithium precipitation agent is 300-350g / L; and / or,

[0057] The stoichiometric ratio of the lithium precipitation agent to lithium ions in the concentrated liquid is 20:11-5:3; and / or,

[0058] The second preset time is 1-2h.

[0059] Step S6, the crude lithium carbonate is sequentially subjected to purification, evaporation and crystallization treatment to obtain a pure lithium carbonate.

[0060] As a preferred scheme of the present application, in the process of sequentially subjecting the crude lithium carbonate to purification, evaporation and crystallization treatment to obtain a pure lithium carbonate,

[0061] The liquid-solid ratio of the pure water to the crude lithium carbonate used in the purification process is 10:1-20:1, and the carbon dioxide is used to purify the crude lithium carbonate at a flow rate of 1-3L / min;

[0062] The evaporation temperature is 80-100°C; and the evaporation time is 1h-10h;

[0063] The temperature of crystallization is 25-30 DEG C; the crystallization time is 2-5h.

[0064] By adding water to the waste lithium iron phosphate positive material, a slurry is prepared, then acid and oxidizing agent are added to the slurry, lithium can be selectively leached by acid leaching combined with the action of oxidizing agent, lithium and iron are separated, the leaching rate of lithium is high, and the leaching selectivity is high; then the first filter residue containing iron is dried, a reducing agent is prepared, and high-temperature reduction treatment is carried out, yellow phosphorus and phosphorus iron are obtained; the first leaching solution containing lithium is sequentially subjected to impurity removal, evaporation concentration, lithium precipitation treatment, and then crude lithium carbonate is obtained, finally, after purification, evaporation and crystallization, pure lithium carbonate is obtained; compared with the existing traditional process, the process flow is simplified, the amount of acid and alkali is reduced, the recovery cost is reduced, zero secondary waste can be achieved, secondary pollution can be avoided, lithium and phosphorus in the waste lithium iron phosphate positive material battery can be recovered at the same time, and the method has strong market competitiveness and application value.

[0065] In order to better explain the method for recovering valuable metals from waste lithium iron phosphate positive material provided by the application and the technical effects achieved, specific examples are verified as follows:

[0066] Example 1

[0067] Step 1, 88.7mL water is added to 20g waste lithium iron phosphate positive material to prepare a slurry;

[0068] Step 2, 4.6mL of 98wt% concentrated sulfuric acid and 6.7mL of 30wt% hydrogen peroxide are added to the slurry, and after reaction at room temperature for 1h, filtration is carried out to obtain a leaching solution and a first filter residue;

[0069] Step 3, after the first leaching solution is filtered to remove impurities, a filtrate and a second filter residue are obtained; and after the first filter residue is dried, it is prepared with coke according to a molar ratio of 2.5:1, and the prepared mixture is placed into a vacuum smelting furnace and subjected to high-temperature reduction at a temperature of 1300 DEG C for 2h to obtain 3.2g of yellow phosphorus and 9.1g of phosphorus iron;

[0070] Step 4, the filtrate is subjected to evaporation concentration treatment for 1h, and the concentration multiple is 10, to obtain a concentrated solution;

[0071] Step 5, 6.5g of sodium carbonate is added to the concentrated solution, and after reaction for 2h, 3.8g of crude lithium carbonate is obtained;

[0072] Step 6, the crude lithium carbonate is purified by using 20:1 of liquid-solid ratio of pure water and crude lithium carbonate, 1L / min of carbon dioxide, then evaporated and crystallized, and 3.6g of pure lithium carbonate is obtained.

[0073] Example 2

[0074] Step 1, 20 g of waste lithium iron phosphate positive electrode material was added with 28 mL of water to prepare a slurry;

[0075] Step 2, 72 mL of 37% concentrated hydrochloric acid and 4.9 g of sodium hypochlorite were added to the slurry, and after reaction at room temperature for 3 h, filtration was performed to obtain a leaching solution and a first filter residue;

[0076] Step 3, after the first leaching solution was filtered to remove impurities, a filtrate and a second filter residue were obtained; and after the first filter residue was dried, it was mixed with coke at a molar ratio of 2.8:1, and the mixture obtained by the mixing was placed into a vacuum smelting furnace for high-temperature reduction at a temperature of 1400°C for 1.5 h to obtain 3.1 g of yellow phosphorus and 8.9 g of ferrophosphorus;

[0077] Step 4, the filtrate was evaporated and concentrated for 5 h to obtain a concentrated solution;

[0078] Step 5, 4.6 g of sodium bicarbonate was added to the concentrated solution, and after reaction for 2 h, 3.4 g of crude lithium carbonate was obtained;

[0079] Step 6, the crude lithium carbonate was purified by using a liquid-solid ratio of 15:1 of pure water to crude lithium carbonate and 2 L / min of carbon dioxide, and then evaporated and crystallized to obtain 3.3 g of pure lithium carbonate.

[0080] Example 3

[0081] Step 1, 20 g of waste lithium iron phosphate positive electrode material was added with 80 mL of water to prepare a slurry;

[0082] Step 2, 20 mL of 68% nitric acid was added to the slurry, and after reaction at room temperature for 1 h, filtration was performed to obtain a leaching solution and a first filter residue;

[0083] Step 3, after the first leaching solution was filtered to remove impurities, a filtrate and a second filter residue were obtained; and after the first filter residue was dried, it was mixed with coke at a molar ratio of 2.6:1, and the mixture obtained by the mixing was placed into a vacuum smelting furnace for high-temperature reduction at a temperature of 1500°C for 1 h to obtain 3.3 g of yellow phosphorus and 8.7 g of ferrophosphorus;

[0084] Step 4, the filtrate was evaporated and concentrated for 10 h to obtain a concentrated solution;

[0085] Step 5, 1.2 L of carbon dioxide was introduced into the concentrated solution, and after reaction for 2 h, 3.7 g of crude lithium carbonate was obtained;

[0086] Step 6, the crude lithium carbonate was purified by using a liquid-solid ratio of 10:1 of pure water to crude lithium carbonate and 3 L / min of carbon dioxide, and then evaporated and crystallized to obtain 3.4 g of pure lithium carbonate.

[0087] It can be seen from the above embodiments 1-3 that:

[0088] 1. The acid leaching method is used to selectively leach lithium from the waste LiFePO4 positive electrode material, realizes one-step separation of lithium and iron, has high lithium leaching rate and leaching selectivity.

[0089] 2. Compared with the traditional process, the process flow is simplified, the amount of acid and alkali is reduced, the recovery cost is reduced, zero secondary waste is realized, and secondary pollution is avoided.

[0090] 3. The simultaneous recovery of lithium and phosphorus in the waste LiFePO4 battery is realized, which has strong market competitiveness and application value.

[0091] It should be noted that the above specific embodiments are only used to verify the effect of the method for recovering valuable metals from waste lithium iron phosphate positive electrode material provided by the present application in actual experiment, and do not limit the technical solutions provided by the present application.

[0092] As can be seen from the above specific embodiments, by adding water to the waste lithium iron phosphate positive electrode material to prepare a slurry, then adding acid and oxidizing agent to the slurry, the acid leaching method combined with the action of the oxidizing agent can be used to selectively leach lithium, realize the separation of lithium and iron, and has high lithium leaching rate and leaching selectivity; then the first filter residue containing iron is dried, the reducing agent is dosed and high-temperature reduction treatment is carried out to obtain yellow phosphorus and phosphorus iron; the first leaching liquid containing lithium is sequentially subjected to impurity removal, evaporation concentration, lithium precipitation treatment to obtain crude lithium carbonate, and finally the pure lithium carbonate is obtained after purification, evaporation and crystallization purification treatment; compared with the existing traditional process, the process flow is simplified, the amount of acid and alkali is reduced, thereby reducing the recovery cost, achieving zero secondary waste generation and avoiding secondary pollution; the simultaneous recovery of lithium and phosphorus in the waste lithium iron phosphate positive electrode material battery can be achieved, which has strong market competitiveness and application value.

[0093] The method for recovering valuable metals from waste lithium iron phosphate positive electrode material according to the present application is described above with reference to the accompanying drawings in an exemplary manner. However, those skilled in the art should understand that various improvements can be made to the above-mentioned method for recovering valuable metals from waste lithium iron phosphate positive electrode material according to the present application without departing from the content of the present application. Therefore, the protection scope of the present application should be determined by the content of the appended claims.

Claims

1. A method for recovering valuable metals from spent lithium iron phosphate cathode material, characterized in that, The method comprises the following steps: adding water to the waste lithium iron phosphate positive electrode material to prepare a slurry; adding an acid solution and an oxidizing agent to the slurry, filtering after reacting for a first preset time to obtain a leaching solution and a first filter residue; filtering the first leaching solution to remove impurities to obtain a filtrate and a second filter residue; and drying the first filter residue, then mixing the dried first filter residue with a reducing agent at a preset ratio, and placing the mixture in a vacuum smelting furnace for high-temperature reduction to obtain yellow phosphorus and ferrophosphorus; evaporating and concentrating the filtrate to obtain a concentrated solution; adding a lithium precipitating agent to the concentrated solution, and reacting for a second preset time to obtain crude lithium carbonate; purifying, evaporating, and crystallizing the crude lithium carbonate in sequence to obtain pure lithium carbonate.

2. The method for recovering valuable metals from waste old lithium iron phosphate positive electrode material according to claim 1, characterized in that, In the process of adding water to the waste lithium iron phosphate positive electrode material to prepare a slurry, the mass-volume ratio of the waste lithium iron phosphate positive electrode material to water is 1:2-1:

10.

3. The method for recovering valuable metals from waste old lithium iron phosphate positive electrode material according to claim 1, characterized in that, The acid solution is any one of sulfuric acid, phosphoric acid, and nitric acid, or at least two of them mixed in any ratio; and / or, The volume ratio of the acid solution to the slurry is 1:1-1:

5.

4. The method for recovering valuable metals from waste old lithium iron phosphate positive electrode material according to claim 1, characterized in that, The oxidizing agent is any one of hydrogen peroxide, hypochlorite, and oxygen, or at least two of them mixed in any ratio; and / or, The volume ratio of the oxidizing agent to the slurry is 1:1-1.2:

1.

5. The method for recovering valuable metals from waste old lithium iron phosphate positive electrode material according to claim 1, characterized in that, The first preset time is 1-3h.

6. The method for recovering valuable metals from waste old lithium iron phosphate positive electrode material according to claim 1, characterized in that, The reducing agent is any one of coke, pulverized coal, and carbon monoxide, or at least two of them mixed in any ratio; and / or, The molar ratio of the dried first filter residue to the reducing agent is 2.5:

1.

7. The method for recovering valuable metals from waste old lithium iron phosphate positive electrode material according to claim 1, characterized in that, The reduction temperature of the mixture in the vacuum smelting furnace is 1300℃-1500℃; and the high-temperature reduction time is 0.5-2h.

8. The method for recovering valuable metals from waste old lithium iron phosphate positive electrode material according to claim 1, characterized in that, In the process of evaporating and concentrating the filtrate to obtain a concentrated solution, the concentration multiple of the evaporating and concentrating treatment is 10-30.

9. The method for recovering valuable metals from waste old lithium iron phosphate positive electrode material according to claim 1, characterized in that, The lithium precipitating agent is any one of sodium carbonate, carbon dioxide, and sodium bicarbonate, or at least two of them mixed in any ratio; and / or, The concentration of the lithium precipitating agent is 300-350g / L; and / or, The stoichiometric ratio of the lithium precipitating agent to lithium ions in the concentrated solution is 20:11-5:3; and / or, The second preset time is 1-2h.

10. The method of recovering valuable metals from spent lithium iron phosphate cathode material according to claim 1, wherein, In the process of purifying, evaporating, and crystallizing the crude lithium carbonate in sequence to obtain pure lithium carbonate, The liquid-solid ratio of pure water to crude lithium carbonate used in the purifying process is 10:1-20:1, and the carbon dioxide used in the purifying process is 1-3L / min; The evaporation temperature is 80-100℃; and the evaporation time is 1h-10h; The crystallization temperature is 25-30℃; and the crystallization time is 2-5h.

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