Method for extracting lithium from clay lithium ore

Abstract

The invention provides a method for extracting lithium from clay lithium ore, and belongs to the technical field of extraction of lithium from lithium ore, the method comprises the following steps: mixing the clay lithium ore with a dissociation agent, carrying out ball milling to obtain an abrasive, sequentially carrying out leaching, evaporation thickening, impurity removal, crystallization and alkali liquor addition to obtain crude lithium carbonate, and purifying the crude lithium carbonate to obtain pure lithium carbonate. A simple process of mechanical activation-wet lithium extraction is utilized in the whole process, and the lithium recovery rate is high; under the combined action of a mechanical field and a thermal field, lithium in the lithium ore can be directly extracted, operations such as roasting modification are not needed, and procedures and energy consumption are greatly reduced; the method has the advantages of green development and utilization of clay lithium ore, energy conservation, emission reduction, cost reduction and the like.

Description

Technical Field

[0001] This invention relates to the field of lithium extraction technology, and more specifically, to a method for extracting lithium from clay lithium ore. Background Technology

[0002] Clay-type lithium deposits, also known as sedimentary lithium deposits or unconventional lithium deposits, are characterized by their wide distribution and large reserves. Based on their formation, they are classified into volcanic clay-type lithium deposits (low aluminum, high magnesium), carbonate clay-type lithium deposits (aluminum and silicon content are close, magnesium content is low), and jadal lithium deposits. In volcanic clay-type lithium deposits, lithium is mainly found within the crystal lattice of montmorillonite group minerals or illite, belonging to structural lithium. In carbonate clay-type lithium deposits, lithium mainly exists in an adsorbed form within the interlayer of clay minerals such as montmorillonite, belonging to adsorbed lithium.

[0003] Currently, research on clay-type lithium ores is relatively limited. Existing technologies typically employ high-temperature roasting for activation, followed by acid leaching to extract lithium. For example, patent application number 201410098348.9 discloses a method for extracting lithium from low-grade lithium-bearing clay ores, proposing a new process of "modified roasting-heap leaching," which solves the problem of lithium extraction from low-grade clay-type lithium ores. However, this technology has certain shortcomings; roasting and the addition of auxiliary materials not only increase costs but also increase impurity content. Another example is patent application number 201910788413.3, which discloses a method for extracting lithium from carbonate clay-type lithium ores using ion exchange, proposing a new process of using iron salt solutions for leaching. The lithium leaching rate can reach over 90%. However, this method requires roasting and modifying the lithium ore at 450–800℃, resulting in high energy consumption, high cost, large slag volume, and high pollution. For example, patent application number 202210819588.8 discloses a method for extracting lithium from low-alumina lithium-rich clay. This method avoids the complex mineral processing desulfurization-roasting process by using hot-press leaching, thereby improving the lithium leaching rate. However, it suffers from problems such as high acid consumption and severe pollution.

[0004] Therefore, in summary, due to the low lithium grade of clay lithium ore, conventional beneficiation methods in the existing technology have problems such as difficulty in enriching and recovering lithium, strong acidity of leachate, and high risk of environmental pollution from reaction residues.

[0005] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0006] In view of the above problems, the purpose of this invention is to provide a method for extracting lithium from clay lithium ore, so as to solve the problems in the prior art, which are that due to the low lithium grade of clay lithium ore, conventional mineral processing methods are difficult to enrich and recover lithium, the leaching solution is highly acidic, and the reaction residue poses a high risk of environmental pollution.

[0007] This invention provides a method for extracting lithium from clay lithium ore, comprising the following steps:

[0008] The mixture obtained by mixing clay lithium ore with a dissociation agent is put into a ball mill for ball milling to obtain grinding material;

[0009] Water is added to the abrasive material for leaching treatment, and after a first preset time, it is filtered to obtain a first filtrate and a first filter residue.

[0010] Water is added to the first filter residue for washing, and after filtration, a second filtrate and a second filter residue are obtained.

[0011] The second filtrate is mixed with the first filtrate and then evaporated to concentrate, resulting in a concentrated liquid.

[0012] The concentrated liquid is purified by passing it through an ion exchange column to remove impurities, resulting in a purified liquid.

[0013] The purified liquid is evaporated and filtered to obtain crystals and a third filtrate.

[0014] Add alkaline solution to the third filtrate and stir. After standing for a second preset time, filter to obtain crude lithium carbonate.

[0015] The crude lithium carbonate was purified to obtain pure lithium carbonate.

[0016] Furthermore, in a preferred embodiment, the dissociation agent is any one of sulfuric acid, phosphoric acid, and nitric acid;

[0017] The amount of the dissociating agent used is 1.1-1.2 times the stoichiometric ratio of the dissociating agent to the lithium in the clay lithium ore.

[0018] Furthermore, a preferred embodiment is that, during the process of ball milling the mixture obtained by mixing clay lithium ore with a dissociation agent to obtain grinding material, the ball milling time of the mixture in the ball mill is 1-3 hours.

[0019] Furthermore, a preferred embodiment involves adding water to the abrasive for leaching, followed by filtration after a first preset time to obtain a first filtrate and a first filter residue.

[0020] The mass-to-volume ratio of the abrasive to water is 1:3-1:10 g / mL;

[0021] The first preset time is 1-3 hours.

[0022] Furthermore, in a preferred embodiment, during the process of adding water to the first filter residue for washing and filtering to obtain the second filtrate and the second filter residue, the mass-to-volume ratio of the first filter residue to the water is 1:2-1:5 g / ml.

[0023] In addition, a preferred embodiment is that, in the process of mixing the second filtrate with the first filtrate and then evaporating and concentrating it to obtain a concentrated liquid, the evaporation and concentration time is 1h-10h and the concentration factor is 10-30.

[0024] Furthermore, in a preferred embodiment, the reaction time of the ion exchange resin is 2-8 hours during the process of removing impurities from the concentrated liquid by passing it through an ion exchange resin column to obtain a purified liquid.

[0025] Furthermore, in a preferred embodiment, during the process of evaporating and filtering the purified liquid to obtain crystals and a third filtrate, the evaporation temperature of the purified liquid is 80-100℃, and the evaporation time is 1-5 hours.

[0026] Furthermore, a preferred embodiment is that during the process of adding alkaline solution to the third filtrate, stirring, allowing it to stand for a second preset time, and then filtering to obtain crude lithium carbonate,

[0027] The alkaline solution is a sodium carbonate solution;

[0028] CO3 in the alkaline solution 2- With the Li in the third filtrate + The ratio is 3:5; the stirring time is 1-3 hours.

[0029] The settling time is 1-2 hours.

[0030] Furthermore, in a preferred embodiment, the purification process of the crude lithium carbonate to obtain pure lithium carbonate includes:

[0031] The crude lithium carbonate is sequentially washed, filtered, and dried to obtain dried crude lithium carbonate; wherein, during the washing of the crude lithium carbonate, the mass-to-volume ratio of the crude lithium carbonate to water is 1:2-1:5 g / ml.

[0032] The dried crude lithium carbonate is subjected to purification, evaporation, and crystallization processes in sequence to obtain pure lithium carbonate. During the purification process of the dried crude lithium carbonate, a liquid-to-solid ratio of pure water to crude sodium carbonate of 10:1-20:1 and a carbon dioxide flow rate of 2-3 L / min are used.

[0033] As can be seen from the above technical solution, the method for extracting lithium from clay lithium ore provided by the present invention involves leaching, evaporating and concentrating, removing impurities, crystallizing, and adding alkaline solution to obtain crude lithium carbonate after mixing clay lithium ore with a dissociation agent and then ball milling the resulting grinding material. The crude lithium carbonate is then purified to obtain pure lithium carbonate. The entire process utilizes a simple "mechanical activation-wet lithium extraction" process, resulting in a high lithium recovery rate. Under the combined action of a mechanical field and a thermal field, lithium can be directly extracted from the lithium ore without roasting or modification, greatly reducing the number of processes and energy consumption. It has the advantages of green development and utilization of clay lithium ore, energy conservation and emission reduction, and cost reduction.

[0034] To achieve the foregoing and related objectives, and in accordance with one or more aspects of the invention, the features described in detail below are included. Certain exemplary aspects of the invention are illustrated in detail below with reference to the accompanying drawings. However, these aspects indicate only a few of the various ways in which the principles of the invention can be used. Furthermore, the invention is intended to encompass all such aspects and their equivalents. Attached Figure Description

[0035] Other objects and results of the invention will become more apparent and readily understood with reference to the following description taken in conjunction with the accompanying drawings, and with a more complete understanding of the invention.

[0036] Figure 1 This is a flowchart of a method for extracting lithium from clay lithium ore according to an embodiment of the present invention. Detailed Implementation

[0037] In the following description, numerous specific details are set forth for illustrative purposes and to provide a thorough understanding of one or more embodiments. However, it will be apparent that these embodiments may also be implemented without these specific details.

[0038] In view of the aforementioned existing technologies, due to the low lithium grade of clay lithium ore, conventional beneficiation methods have problems such as difficulty in enriching and recovering lithium, strong acidity of leachate, and high environmental pollution risk of reaction residue. Therefore, a method for extracting lithium from clay lithium ore is proposed.

[0039] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0040] To illustrate the method for extracting lithium from clay lithium ore provided by the present invention Figure 1 A process flow diagram of a method for extracting lithium from clay lithium ore according to an embodiment of the present invention is shown.

[0041] The method for extracting lithium from clay lithium ore provided by the present invention includes the following steps:

[0042] Step S1: The mixture obtained by mixing clay lithium ore and dissociation agent is put into a ball mill for ball milling to obtain grinding material.

[0043] Specifically, clay lithium ore and a dissociation agent are mixed in a preset ratio to obtain a mixture. The mixture is then added to a ball mill, such as a ball mill, and milled for a certain period of time to obtain abrasive material. The particle size of the abrasive material can be determined according to the actual situation, and this invention does not impose any particular limitation on it.

[0044] As a preferred embodiment of the present invention, the dissociation agent is any one of sulfuric acid, phosphoric acid, and nitric acid; the mass fraction of the acid is 1%-50%; and the amount of dissociation agent used is 1.1-1.2 times the stoichiometric ratio of the dissociation agent to lithium in the clay lithium ore.

[0045] In a preferred embodiment of the present invention, the mixture obtained by mixing clay lithium ore with a dissociation agent is placed in a ball mill for ball milling to obtain the grinding material.

[0046] The ball milling time for the mixture in the ball milling equipment is 1h-3h.

[0047] It should be noted that the dissociation agent in this invention is preferably, but not limited to, sulfuric acid, phosphoric acid, and nitric acid; the amount of dissociation agent is preferably, but not limited to, 1.1-1.2 times the stoichiometric ratio of the dissociation agent to lithium in the clay lithium ore; the ball milling time can also be determined according to actual requirements, and this invention does not impose any special limitations on this.

[0048] Step S2: Add water to the grinding material for leaching treatment, filter after a first preset time to obtain the first filtrate and the first filter residue.

[0049] Specifically, a certain amount of room temperature water is added to the grinding material, and the components in the grinding material are leached out under the action of acid, thereby obtaining the first filtrate and the first filter residue. The first filtrate is a lithium-containing solution.

[0050] In a preferred embodiment of the present invention, during the process of adding water to the grinding material for leaching treatment, filtering after a first preset time, and obtaining a first filtrate and a first filter residue,...

[0051] The mass-to-volume ratio of abrasive to water is 1:3-1:10 g / mL;

[0052] The first preset time is 1-3 hours.

[0053] Step S3: Add water to the first filter residue for washing, and after filtration, obtain the second filtrate and the second filter residue.

[0054] Specifically, to avoid lithium residue in the first filter residue, water is added to wash it. Room temperature water is sufficient for washing. After filtration, a second filtrate and a second filter residue are obtained. The second filtrate is a lithium-containing solution.

[0055] In a preferred embodiment of the present invention, during the process of adding water to the first filter residue for washing, and filtering to obtain the second filtrate and the second filter residue,...

[0056] The mass-to-volume ratio of the first filter residue to water is 1:2-1:5 g / ml.

[0057] Specifically, the mass-to-volume ratio here refers to the ratio between the mass of the first filter residue and the volume of the washing water. For example, if the mass-to-volume ratio of the first filter residue to water is 1:2, it means that 1g of the first filter residue is added to 2ml of water.

[0058] Step S4: Mix the second filtrate with the first filtrate and then evaporate and concentrate to obtain a concentrated liquid.

[0059] Specifically, the two lithium-containing solutions (the first filtrate and the second filtrate) are mixed and then evaporated to obtain a concentrated solution.

[0060] In a preferred embodiment of the present invention, during the process of mixing the second filtrate with the first filtrate and then evaporating and concentrating the mixture to obtain a concentrated liquid...

[0061] The evaporation and concentration time is 1-10 hours, and the concentration factor is 10-30.

[0062] Step S5: After passing the concentrated liquid through an ion exchange column to remove impurities, a purified liquid is obtained.

[0063] Specifically, impurities in the concentrated liquid are removed by adding it to an ion exchange column for ion exchange treatment, thereby obtaining a purified liquid.

[0064] As a preferred embodiment of the present invention, in the process of obtaining purified liquid after impurity removal by passing the concentrated liquid through an ion exchange column, the reaction time of the ion exchange is preferably 2h-8h.

[0065] Step S6: Evaporate and filter the purified liquid to obtain crystals and a third filtrate.

[0066] Specifically, the purified liquid is evaporated again, and then filtered to obtain crystals and a third filtrate. The crystals are sodium sulfate and potassium sulfate, or one of both, primarily based on lithium ore components. The third filtrate is a lithium-containing solution.

[0067] In a preferred embodiment of the present invention, during the process of evaporating and filtering the purified liquid to obtain crystals and a third filtrate...

[0068] The evaporation temperature of the purification liquid is 80-100℃; the evaporation time is 1-5 hours.

[0069] Step S7: Add alkaline solution to the third filtrate and stir. After standing for a second preset time, filter to obtain crude lithium carbonate.

[0070] Specifically, an alkaline solution is added to the third filtrate. The lithium-containing solution reacts with the alkaline solution to produce lithium carbonate. Stirring ensures that the reaction is complete. After standing for a certain period of time, the crude lithium carbonate is obtained by filtration.

[0071] In a preferred embodiment of the present invention, after adding alkaline solution to the third filtrate and stirring, the mixture is allowed to stand for a second preset time before filtration to obtain crude lithium carbonate.

[0072] The alkaline solution is a sodium carbonate solution;

[0073] CO3 in alkaline solution 2- With Li in the third filtrate + The ratio is 3:5;

[0074] The stirring time is 1-3 hours;

[0075] The settling time is 1-2 hours.

[0076] Step S8: Purify the crude lithium carbonate to obtain pure lithium carbonate.

[0077] As a preferred embodiment of the present invention, the crude lithium carbonate is purified to obtain pure lithium carbonate, comprising:

[0078] The crude lithium carbonate was sequentially washed, filtered, and dried to obtain dried crude lithium carbonate; wherein, during the washing of the crude lithium carbonate, the mass-to-volume ratio of crude lithium carbonate to water was 1:2-1:5 g / ml.

[0079] The dried crude lithium carbonate was subjected to purification, evaporation, and crystallization processes to obtain pure lithium carbonate. During the purification process of the dried crude lithium carbonate, a liquid-to-solid ratio of pure water to crude sodium carbonate of 10:1-20:1 and a carbon dioxide flow rate of 2-3 L / min were used.

[0080] Crude lithium carbonate is obtained by ball milling a mixture of clay lithium ore and a dissociation agent, followed by leaching, evaporation and concentration, impurity removal, crystallization, and addition of alkali solution. The crude lithium carbonate is then purified to obtain pure lithium carbonate. The entire process utilizes a simple "mechanical activation-wet lithium extraction" technique, resulting in a high lithium recovery rate. Under the combined action of mechanical and thermal fields, lithium can be directly extracted from the ore without roasting or modification, significantly reducing processes and energy consumption. This method offers advantages such as green development and utilization of clay lithium ore, energy conservation and emission reduction, and cost reduction.

[0081] To better illustrate the method for extracting lithium from clay lithium ore provided by this invention and its technical effects, specific embodiments are provided as follows:

[0082] Example 1

[0083] Step S1: Mix 200g of low-grade clay lithium ore with 1000mL of sulfuric acid with a mass fraction of 30% and then put the mixture into a ball mill and ball mill for 3 hours to obtain the grinding material.

[0084] Step S2: Add 600mL of water to the grinding material and leach for 3 hours, then filter to obtain the first filtrate and the first filter residue;

[0085] Step S3: Add water to the first filter residue for washing, and after filtration, obtain the second filtrate and the second filter residue;

[0086] Step S4: Mix the second filtrate with the first filtrate and evaporate and concentrate for 10 hours, with a concentration factor of 30, to obtain a concentrated liquid;

[0087] Step S5: Pass the concentrated liquid through an ion exchange column for 2 hours to remove impurities and obtain a purified liquid.

[0088] Step S6: Evaporate and filter the purified liquid to obtain crystals and a third filtrate; wherein the evaporation temperature is 80℃ and the evaporation time is 3h.

[0089] Step S7: After adding alkaline solution to the third filtrate and stirring, let it stand for 1 hour and then filter to obtain 2.38 g of crude lithium carbonate; wherein, the CO3 in the alkaline solution 2- With Li in the third filtrate + The ratio is 3:5;

[0090] Step S8: The crude lithium carbonate is sequentially washed, filtered, dried, purified, evaporated, and crystallized to obtain pure lithium carbonate. The purification process uses a liquid-to-solid ratio of 20:1 and a carbon dioxide flow rate of 2 L / min, yielding 2.24 g of pure lithium carbonate.

[0091] Example 2

[0092] Step S1: Mix 200g of low-grade clay lithium ore with 1000mL of phosphoric acid with a mass fraction of 20% and then put the mixture into a ball mill and ball mill for 2 hours to obtain the grinding material.

[0093] Step S2: Add 1000mL of water to the grinding material and leach for 2 hours, then filter to obtain the first filtrate and the first filter residue;

[0094] Step S3: Add water to the first filter residue for washing, and after filtration, obtain the second filtrate and the second filter residue;

[0095] Step S4: Mix the second filtrate with the first filtrate and evaporate and concentrate for 5 hours, with a concentration factor of 20, to obtain a concentrated liquid;

[0096] Step S5: Pass the concentrated liquid through an ion exchange column for 2 hours to remove impurities and obtain a purified liquid.

[0097] Step S6: Evaporate and filter the purified liquid to obtain crystals and a third filtrate; wherein the evaporation temperature is 90℃ and the evaporation time is 2h.

[0098] Step S7: After adding alkaline solution to the third filtrate and stirring, let it stand for 1.5 hours and then filter to obtain 2.12 g of crude lithium carbonate; wherein, the alkaline solution contains CO3 2- With Li in the third filtrate + The ratio is 3:5;

[0099] Step S8: The crude lithium carbonate is sequentially washed, filtered, dried, purified, evaporated, and crystallized to obtain pure lithium carbonate. The purification process uses a liquid-to-solid ratio of 15:1 and a carbon dioxide flow rate of 2.5 L / min, yielding 2.01 g of pure lithium carbonate.

[0100] Example 3

[0101] Step S1: Mix 200g of low-grade clay lithium ore with 1000mL of nitric acid with a mass fraction of 40% and then put the mixture into a ball mill and ball mill for 1 hour to obtain the grinding material.

[0102] Step S2: Add 1500mL of water to the grinding material and leach for 1 hour, then filter to obtain the first filtrate and the first filter residue;

[0103] Step S3: Add water to the first filter residue for washing, and after filtration, obtain the second filtrate and the second filter residue;

[0104] Step S4: Mix the second filtrate with the first filtrate and evaporate and concentrate for 8 hours, with a concentration factor of 25, to obtain a concentrated liquid;

[0105] Step S5: Pass the concentrated liquid through an ion exchange column for 2 hours to remove impurities and obtain a purified liquid.

[0106] Step S6: Evaporate and filter the purified liquid to obtain crystals and a third filtrate; wherein the evaporation temperature is 100℃ and the evaporation time is 1h.

[0107] Step S7: After adding alkaline solution to the third filtrate and stirring, let it stand for 1 hour and then filter to obtain 2.23g of crude lithium carbonate; wherein, the CO3 in the alkaline solution 2- With Li in the third filtrate + The ratio is 3:5;

[0108] Step S8: The crude lithium carbonate is sequentially washed, filtered, dried, purified, evaporated, and crystallized to obtain pure lithium carbonate. The purification process uses a liquid-to-solid ratio of 10:1 and a carbon dioxide flow rate of 3 L / min, yielding 2.12 g of pure lithium carbonate.

[0109] As can be seen from the above embodiments 1-3:

[0110] 1. This invention proposes a new "mechanical activation-wet lithium extraction" process for low-grade clay lithium ore. This process is simple and has a high lithium recovery rate.

[0111] 2. Under the combined action of mechanical and thermal fields, this invention can directly extract lithium from lithium ore without roasting or modification, thus reducing processes and energy consumption.

[0112] 3. This invention has advantages such as green development and utilization of clay lithium ore, energy conservation and emission reduction, and cost reduction, and forms a new technology for efficient separation and extraction of clay lithium ore.

[0113] It should be noted that the above specific embodiments are merely for verifying the effectiveness of the method for extracting lithium from clay lithium ore provided by the present invention in actual experimental processes, and do not limit the technical solutions provided by the present invention.

[0114] The method for extracting lithium from clay lithium ore according to the present invention has been described above by way of example with reference to the accompanying drawings. However, those skilled in the art will understand that various modifications can be made to the method for extracting lithium from clay lithium ore according to the present invention without departing from the scope of the invention. Therefore, the scope of protection of the present invention should be determined by the contents of the appended claims.

Claims

1. A method for extracting lithium from clay lithium ore, characterized in that, Includes the following steps: The mixture obtained by mixing clay lithium ore with a dissociation agent is put into a ball mill for ball milling to obtain grinding material; Water is added to the abrasive material for leaching treatment, and after a first preset time, it is filtered to obtain a first filtrate and a first filter residue. Water is added to the first filter residue for washing, and after filtration, a second filtrate and a second filter residue are obtained. The second filtrate is mixed with the first filtrate and then evaporated to concentrate, resulting in a concentrated liquid. The concentrated liquid is purified by passing it through an ion exchange column to remove impurities, resulting in a purified liquid. The purified liquid is evaporated and filtered to obtain crystals and a third filtrate. Add alkaline solution to the third filtrate and stir. After standing for a second preset time, filter to obtain crude lithium carbonate. The crude lithium carbonate was purified to obtain pure lithium carbonate.

2. The method for extracting lithium from clay lithium ore according to claim 1, characterized in that, The dissociation agent is any one of sulfuric acid, phosphoric acid, and nitric acid; The amount of the dissociating agent used is 1.1-1.2 times the stoichiometric ratio of the dissociating agent to the lithium in the clay lithium ore.

3. The method for extracting lithium from clay lithium ore according to claim 1, characterized in that, The mixture obtained by mixing clay lithium ore with a dissociation agent is then fed into a ball mill for ball milling to obtain grinding media. The mixture is ball-milled in the ball mill for 1-3 hours.

4. The method for extracting lithium from clay lithium ore according to claim 1, characterized in that, In the process of adding water to the abrasive for leaching treatment, filtering after a first preset time to obtain a first filtrate and a first filter residue,... The mass-to-volume ratio of the abrasive to water is 1:3-1:10 g / mL; The first preset time is 1-3 hours.

5. The method for extracting lithium from clay lithium ore according to claim 1, characterized in that, During the process of adding water to the first filter residue for washing, filtering, and obtaining the second filtrate and the second filter residue, The mass-to-volume ratio of the first filter residue to the water is 1:2-1:5 g / ml.

6. The method for extracting lithium from clay lithium ore according to claim 1, characterized in that, In the process of mixing the second filtrate with the first filtrate and then evaporating and concentrating the mixture to obtain a concentrated liquid. The evaporation and concentration time is 1-10 hours, and the concentration factor is 10-30.

7. The method for extracting lithium from clay lithium ore according to claim 1, characterized in that, In the process of removing impurities from the concentrated liquid using an ion exchange column to obtain a purified liquid, The reaction time for ion exchange resin is 2-8 hours.

8. The method for extracting lithium from clay lithium ore according to claim 1, characterized in that, During the process of evaporating and filtering the purified liquid to obtain crystals and a third filtrate, The evaporation temperature of the purified liquid is 80-100℃; the evaporation time is 1-5h.

9. The method for extracting lithium from clay lithium ore according to claim 1, characterized in that, During the process of adding alkaline solution to the third filtrate, stirring, allowing it to stand for a second preset time, and then filtering to obtain crude lithium carbonate. The alkaline solution is a sodium carbonate solution; CO3 in the alkaline solution 2- With the Li in the third filtrate + The ratio is 3:5; the stirring time is 1-3 hours. The settling time is 1-2 hours.

10. The method for extracting lithium from clay lithium ore according to claim 1, characterized in that, The purification process of the crude lithium carbonate to obtain pure lithium carbonate includes: The crude lithium carbonate is sequentially washed, filtered, and dried to obtain dried crude lithium carbonate; wherein, during the washing of the crude lithium carbonate, the mass-to-volume ratio of the crude lithium carbonate to water is 1:2-1:5 g / ml. The dried crude lithium carbonate was subjected to purification, evaporation, and crystallization processes in sequence to obtain pure lithium carbonate; In the purification process of dried crude lithium carbonate, a liquid-to-solid ratio of 10:1 to 20:1 of pure water and crude sodium carbonate is used; and carbon dioxide is applied at a rate of 2-3 L / min.

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