Method for preparing lithium-containing product by using lithium-containing solution

Abstract

The invention provides a method for preparing a lithium-containing product from a lithium-containing solution, and relates to the technical field of lithium salt preparation.The method comprises the steps that S1, the lithium-containing solution, organic acid and a first calcium-containing compound are mixed, and after first reaction, a first mixture is obtained; performing first solid-liquid separation on the first mixture to obtain a first filtrate and a first precipitate; s2, mixing the first filtrate with carbon dioxide, and performing a second reaction to obtain a second mixture; performing phase separation on the second mixture to obtain regenerated organic acid and a solution containing LiHCO3; s3, the solution containing LiHCO3 is subjected to pyrolysis treatment, and a third mixture is obtained; performing second solid-liquid separation on the third mixture to obtain a lithium carbonate crude product and pyrolysis mother liquor; wherein the pKa value of the organic acid is greater than the pKa value of the carbonic acid. According to the method, lithium can be effectively extracted from the lithium-containing solution, and the production cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium salt preparation, and in particular, to a method for preparing a lithium-containing product using a lithium-containing solution. Background Art

[0002] Lithium-containing products such as lithium carbonate and lithium hydroxide are key raw materials for preparing battery cathode materials. At present, there are mainly two production methods for these lithium-containing products: lithium extraction from brine and lithium extraction from ore. Among them, lithium extraction from brine mainly uses the method of alkaline evaporation crystallization, and uses sodium carbonate, potassium carbonate, calcium carbonate or barium carbonate, etc. to precipitate lithium. Eventually, the produced lithium salt will contain impurities such as calcium, magnesium, barium, potassium, and sodium. These impurities affect the quality of the lithium salt product, and the recovery rate of lithium extraction from brine is very low. Lithium extraction from ore is to leach lithium ore with sulfuric acid to dissolve lithium from the ore to form a lithium sulfate solution. At present, sodium carbonate is mainly used to react with the lithium sulfate solution to prepare a lithium carbonate product. There is also a method of using sodium hydroxide to react with the lithium sulfate solution, and after freezing and denitrification and evaporation crystallization to obtain lithium hydroxide, and then using carbon dioxide to react with lithium hydroxide to prepare lithium carbonate. However, the lithium-containing products prepared by these methods have low purity and high production costs. Summary of the Invention

[0003] The main object of the present invention is to provide a method for preparing a lithium-containing product using a lithium-containing solution, so as to solve the problems of low purity and high production cost of the lithium-containing product in the existing process of preparing a lithium-containing product using a lithium-containing solution.

[0004] To achieve the above object, on the one hand, the present invention provides a method for preparing a lithium-containing product using a lithium-containing solution, including:

[0005] S1, mixing the lithium-containing solution, an organic acid and a first calcium-containing compound to form a slurry to be reacted; after the first reaction of the slurry to be reacted, a first mixture is obtained; the first mixture is subjected to first solid-liquid separation to obtain a first filtrate and a first precipitate;

[0006] S2, mixing the first filtrate with carbon dioxide to obtain a reaction system to be reacted; after the second reaction of the reaction system to be reacted, a second mixture is obtained; the second mixture is subjected to phase separation to obtain a regenerated organic acid and a solution containing LiHCO 3 ;

[0007] S3, performing pyrolysis treatment on the solution containing LiHCO 3 to obtain a third mixture; the third mixture is subjected to second solid-liquid separation to obtain a crude lithium carbonate product and a pyrolysis mother liquor;

[0008] Wherein, the pKa value of the organic acid is greater than the pKa value of carbonic acid.

[0009] Further, it also includes: S4, after washing the crude lithium carbonate product and performing the third solid-liquid separation, obtaining a refined lithium carbonate product; and / or,

[0010] S3 also includes returning the regenerated organic acid to S1 to be mixed with the lithium-containing solution and the first calcium-containing compound to form a slurry to be reacted.

[0011] Further, it also includes: S5, mixing the crude lithium carbonate product or the refined lithium carbonate product, the second calcium-containing compound and water to obtain a mixture to be reacted; after the third reaction of the mixture to be reacted, obtaining a fourth mixture; performing the fourth solid-liquid separation on the fourth mixture to obtain calcium carbonate precipitate and lithium hydroxide solution; performing evaporation crystallization on the lithium hydroxide solution to obtain a lithium hydroxide product.

[0012] Further, the organic acid includes at least one of phenol, bisphenol A, and bisphenol S.

[0013] Further, the first calcium-containing compound and the second calcium-containing compound each independently include calcium oxide and / or calcium hydroxide.

[0014] Further, the lithium-containing solution contains lithium sulfate;

[0015] Preferably, the molar ratio of the organic acid to lithium sulfate in the lithium-containing solution is (0.8 - 5):1;

[0016] Preferably, the molar ratio of the first calcium-containing compound to lithium sulfate in the lithium-containing solution is (0.8 - 5):1.

[0017] Further, the temperature of the first reaction is 30°C to 95°C, and the time of the first reaction is 0.5 h to 5 h; and / or,

[0018] The temperature of the second reaction is 10°C to 50°C; and / or,

[0019] The temperature of the pyrolysis treatment is 80°C to 95°C.

[0020] Further, the concentration of lithium oxide in the first filtrate is 5 g / L to 20 g / L; and / or,

[0021] The pH value of the second mixture is 8 to 10; and / or,

[0022] The concentration of lithium oxide in the pyrolysis mother liquor is 5 g / L to 8 g / L.

[0023] Further, S1 also includes: first performing freezing treatment on the lithium-containing solution to obtain a mixture; performing the fifth solid-liquid separation on the mixture to obtain a purified lithium-containing solution and sodium sulfate impurities; mixing the purified lithium-containing solution, the organic acid and the first calcium-containing compound to form a slurry to be reacted.

[0024] Further, the freezing treatment includes a first-stage freezing and a second-stage freezing. The temperature of the first-stage freezing is 10°C to 15°C, and the temperature of the second-stage freezing is 0°C to 5°C.

[0025] Applying the technical solution of the present application, through step-by-step reactions, lithium can be effectively extracted from the lithium-containing solution. The prepared lithium-containing product has high purity, can meet the requirements of battery grade, and can recycle organic acids, reducing the consumption of reagents and the production cost. In addition, by using cheap and easily available calcium-containing compounds as reaction raw materials, the production cost is further reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The specification drawings forming a part of the present application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0027] Figure 1 It is a flowchart of a method for preparing a lithium-containing product using a lithium-containing solution in an embodiment of the present application;

[0028] Figure 2 It is a flowchart of a method for preparing a lithium-containing product using a lithium-containing solution in another embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the embodiments.

[0030] As described in the background art, in the existing process for preparing a lithium-containing product using a lithium-containing solution, there are problems such as low purity of the lithium-containing product and high production cost. To solve the above technical problems, as Figure 1 shown, the present application provides a method for preparing a lithium-containing product using a lithium-containing solution, including:

[0031] S1, mixing the lithium-containing solution, the organic acid and the first calcium-containing compound to form a slurry to be reacted; after the first reaction of the slurry to be reacted, a first mixture is obtained; the first mixture is subjected to a first solid-liquid separation to obtain a first filtrate and a first precipitate;

[0032] S2, mixing the first filtrate with carbon dioxide to obtain a reaction system to be reacted; after the second reaction of the reaction system to be reacted, a second mixture is obtained; the second mixture is subjected to a phase separation to obtain a regenerated organic acid and a solution containing LiHCO 3 ;

[0033] S3, pyrolyzing the solution containing LiHCO 3 to obtain a third mixture; the third mixture is subjected to a second solid-liquid separation to obtain a crude lithium carbonate product and a pyrolysis mother liquor;

[0034] Among them, the pKa value of the organic acid is greater than the pKa value of carbonic acid.

[0035] In this application, the lithium-containing solution contains a lithium salt. For example, the lithium-containing solution can be a lithium sulfate solution formed by sulfuric acid leaching of lithium ore. At this time, the lithium salt in the lithium-containing solution is lithium sulfate (Li 2 SO 4 ).

[0036] In this application, the pKa value of the organic acid is greater than the pKa value of carbonic acid. It can be understood that the ability of the organic acid in this application to dissociate into H + in water is weaker than that of carbonic acid. Specifically, the pKa value is the negative logarithm of the acid dissociation constant, which is used to measure the index of the ability of an acid to release and dissociate into H + in a solution. Ka is the acid dissociation constant, which represents the ratio of the equilibrium concentration of H + produced by the dissociation of an acid to the concentration of undissociated acid molecules at a certain temperature. The larger the pKa value, the smaller the Ka value of the acid, and the weaker the acidity; the smaller the pKa value, the larger the Ka value, and the stronger the acidity. It can be understood that the pKa value of the organic acid in this application is greater than the pKa value of carbonic acid, that is, the Ka value of the organic acid in this application is less than the Ka value of carbonic acid, and the acidity of the organic acid (HT) is less than that of carbonic acid (H 2 CO 3 ).

[0037] In step S1, the lithium-containing solution, the organic acid, and the first calcium-containing compound are mixed together to form a slurry to be reacted. The organic acid can preferentially form a stable salt with the lithium ions of the lithium salt in the lithium-containing solution. Specifically, when the lithium salt in the lithium-containing solution is lithium sulfate (Li 2 SO 4 ), in the first reaction process, lithium sulfate, the organic acid (HT), and the first calcium-containing compound react to form calcium sulfate precipitation and LiT (i.e., the salt formed by lithium and the organic acid), obtaining a first mixture. After the first solid-liquid separation, a first filtrate and a first precipitate are obtained. Among them, the first filtrate is a solution containing LiT, and the first precipitate is a precipitate containing calcium sulfate. The first filtrate is used for subsequent steps. The first precipitate contains calcium sulfate and can be treated as a by-product or reused. For example, it can be mixed with lithium slag to prepare a gelling material, and this gelling material can be used in the production of building materials, such as the production of gypsum boards, gypsum bricks, gypsum blocks, etc.

[0038] In step S2, the first filtrate is mixed with carbon dioxide gas to form a reaction system to be reacted. Carbon dioxide reacts with LiT in the first filtrate to generate LiHCO 3 (lithium bicarbonate) and regenerated organic acid, obtaining a second mixture. The chemical equation of the second reaction is: LiT + CO 2 + H2 O = LiHCO 3 + HT, realizing the conversion from LiT to LiHCO 3 and the regeneration of organic acid. Since the acidity of the organic acid is less than that of carbonic acid, it will not dissolve in the lithium bicarbonate (LiHCO 3 ) solution. At the same time, the organic acid is in the organic phase. Therefore, the second mixture can be phase-separated by standing and layering to obtain the regenerated organic acid and the solution containing LiHCO 3 . The solution containing LiHCO 3 is used for subsequent steps, and the regenerated organic acid can be reused.

[0039] In step S3, the solution containing LiHCO 3 is heated to carry out a pyrolysis reaction to generate Li 2 CO 3 (lithium carbonate) and water, and at the same time, carbon dioxide is released. The equation of the pyrolysis reaction is: 2LiHCO 3 = Li 2 CO 3 + CO 2 + H 2 O. The pyrolysis treatment realizes the conversion from LiHCO 3 to Li 2 CO 3 , obtaining a crude lithium carbonate product. The third mixture includes lithium carbonate and possible undecomposed LiHCO 3 residues. The third mixture is separated by the second solid-liquid separation to separate the crude lithium carbonate product and the pyrolysis mother liquor. The pyrolysis mother liquor may contain unreacted LiHCO 3 and other impurities, which can be further processed or recycled according to specific needs.

[0040] This application effectively utilizes raw materials such as organic acids, calcium-containing compounds, and carbon dioxide to realize the conversion from a lithium-containing solution with a higher cost to a lithium-containing product with a higher value. Compared with the prior art, this application uses an organic acid with a pKa value greater than that of carbonic acid, that is, an organic acid with an acidity less than that of carbonic acid, as an acidifying agent, which not only improves the selectivity and efficiency of the reaction, reduces energy consumption, but also can significantly reduce the production cost by recycling the organic acid, improves the resource utilization efficiency, and is particularly suitable for extracting high-purity lithium products from low-concentration or low-purity lithium resources.

[0041] The crude lithium carbonate product can be further processed to obtain a lithium carbonate product with a higher purity. In some embodiments, it further includes: S4, washing the crude lithium carbonate product and performing the third solid-liquid separation to obtain a refined lithium carbonate product. The residual solution is removed by washing, and the washing liquid is separated from the solid phase by the third solid-liquid separation. The obtained solid phase is the refined lithium carbonate product.

[0042] In some embodiments, S3 further includes: returning the regenerated acidifying agent to S1 to be mixed with the lithium-containing solution and the first calcium-containing compound to form a slurry to be reacted. In this way, the regenerated organic acid can be reused in step S1, reducing the demand and cost of fresh organic acid and lowering the production cost.

[0043] In some embodiments, as Figure 2 shown, it further includes: S5, mixing the crude lithium carbonate or refined lithium carbonate, the second calcium-containing compound and water to obtain a mixture to be reacted; after the mixture to be reacted undergoes a third reaction, a fourth mixture is obtained; the fourth mixture is subjected to a fourth solid-liquid separation to obtain calcium carbonate precipitate and lithium hydroxide solution; the lithium hydroxide solution is subjected to evaporation crystallization to obtain lithium hydroxide product. High-purity lithium hydroxide product can be obtained through step S5. In the specific implementation process of the present invention, lithium-containing products such as crude lithium carbonate, refined lithium carbonate, and lithium hydroxide product can be obtained according to actual needs.

[0044] Specifically, the crude lithium carbonate or refined lithium carbonate is mixed with the second calcium-containing compound and an appropriate amount of water. Water serves as a reaction medium, enabling lithium carbonate and the second calcium-containing compound to fully contact and undergo a chemical reaction to generate calcium carbonate (CaCO 3 ) precipitate and lithium hydroxide (LiOH) solution, obtaining a fourth mixture; the fourth mixture is subjected to a fourth solid-liquid separation to obtain calcium carbonate precipitate and pure lithium hydroxide solution; the obtained lithium hydroxide solution is evaporated and concentrated, and then cooled and crystallized to obtain a lithium hydroxide solid product. This process can evaporate the water in the lithium hydroxide solution, increasing the concentration of LiOH. When the solution is supersaturated, LiOH precipitates in the form of crystals. Among them, the generated calcium carbonate precipitate can be used as a by-product in industries such as building materials, realizing the reuse of resources.

[0045] The present invention does not limit the specific type of organic acid, as long as the pKa value is greater than that of carbonic acid. For example, in some embodiments, the organic acid includes at least one of phenol (chemical formula: C 6 H 5 OH), bisphenol A (chemical formula: C 15 H 16 O 2 ), and bisphenol S. These organic acids have good chemical stability and regeneration performance, effectively promoting the extraction and conversion process of lithium resources and further reducing the production cost.

[0046] The present invention does not limit the specific types of the first calcium-containing compound and the second calcium-containing compound, as long as the above reaction requirements are met. For example, in some embodiments, the first calcium-containing compound and the second calcium-containing compound each independently include calcium oxide (CaO) and / or calcium hydroxide (Ca(OH) 2 ).

[0047] Specifically, when the first calcium-containing compound is selected from at least one of calcium oxide and calcium hydroxide, the equation of the first reaction is as follows:

[0048] Li 2 SO 4 +2HT+Ca(OH) 2 =2LiT+CaSO 4 +2H 2 O, and / or

[0049] Li 2 SO 4 +2HT+CaO+H 2 O=2LiT+CaSO 4 +2H 2 O.

[0050] When the second calcium-containing compound is selected from at least one of calcium oxide and calcium hydroxide, the equation of the third reaction is as follows:

[0051] Li 2 CO 3 +Ca(OH) 2 =2LiOH+CaCO 3 , and / or,

[0052] Li 2 CO 3 +CaO+H 2 O=2LiOH+CaCO 3 .

[0053] When the lithium-containing solution contains lithium sulfate (Li 2 SO 4 ), in some embodiments, the molar ratio of the organic acid to lithium sulfate in the lithium-containing solution is (0.8 - 5):1, such as 0.8:1, 1:1, 2:1, 3:1, 4:1, 5:1 or the range composed of any two of them. The molar ratio of the first calcium-containing compound to lithium sulfate in the lithium-containing solution is (0.8 - 5):1, such as 0.8:1, 1:1, 2:1, 3:1, 4:1, 5:1 or the range composed of any two of them. By limiting the molar ratios of lithium sulfate in the lithium-containing solution to the organic acid and the calcium-containing compound within the above ranges, it helps to ensure sufficient contact of the reactants, promote the reaction to proceed in the direction of generating the target product, and avoid the occurrence of side reactions.

[0054] In the specific implementation process of the present invention, the organic acid solution and the lithium-containing solution can be first mixed to form an intermediate mixture; the calcium-containing compound and water are mixed to form a calcium-containing slurry; and then the calcium-containing slurry is slowly added to the intermediate mixture for reaction.

[0055] In some embodiments, the temperature of the first reaction is 30°C to 95°C, such as 30°C, 35°C, 40°C, 45°C, 50°C, 60°C, 70°C, 80°C, 90°C, 95°C, or the range composed of any two of them. The time of the first reaction is 0.5 to 5 h, such as 0.5 h, 1 h, 2 h, 3 h, 4 h, 5 h, or the range composed of any two of them. By limiting the temperature and time of the first reaction within the above ranges, it is beneficial to increase the reaction rate, promote the progress of the reaction, and at the same time avoid the occurrence of side reactions.

[0056] In some embodiments, the temperature of the second reaction is 10°C to 50°C, such as 10°C, 15°C, 20°C, 25°C, 30°C, 40°C, 50°C, or the range composed of any two of them. During the second reaction, the temperature directly affects the solubility and reaction rate of CO 2 The solubility and reaction rate of CO 2 in water. A lower temperature can increase the solubility of CO 2 in water, which is beneficial to the progress of the reaction, but the reaction rate will be slower. A higher temperature can increase the reaction rate, but may reduce the solubility of CO

[0057] By limiting the temperature of the second reaction to 10°C to 50°C, the reaction efficiency and selectivity can be balanced, ensuring the full progress of the second reaction and minimizing side reactions as much as possible.

[0057] In some embodiments, the temperature of the pyrolysis treatment is 80°C to 95°C, such as 80°C, 85°C, 90°C, 95°C, or the range composed of any two of them. The choice of pyrolysis temperature directly affects the reaction rate and the completeness of conversion. By limiting the temperature of the pyrolysis treatment to 80°C to 95°C, the decomposition reaction of LiHCO 3 is accelerated and can be more effectively converted into Li 2 CO 3 , while avoiding the further decomposition of Li 2 CO 3 or the occurrence of side reactions.

[0058] The present invention does not limit the reaction endpoints of the first reaction, the second reaction, and the pyrolysis treatment, which can be adjusted according to actual needs. In some embodiments, the concentration of lithium oxide in the first filtrate is 5-20 g / L, such as 5 g / L, 8 g / L, 10 g / L, 12 g / L, 15 g / L, 18 g / L, 20 g / L, or any range composed of any two of them. It can also be understood that the reaction endpoint of the first reaction is that the concentration of lithium oxide in the first filtrate is 5-20 g / L, that is, the concentration of lithium oxide in the first filtrate is 5-20 g / L. In some embodiments, the pH value of the second mixture is 8-10, such as 8, 8.5, 9, 9.5, 10, or any range composed of any two of them. It can also be understood that the reaction endpoint of the second reaction is that the pH value of the second mixture reaches 8-10. In some embodiments, the concentration of lithium oxide in the pyrolysis mother liquor is 5-8 g / L, such as 5 g / L, 6 g / L, 7 g / L, 8 g / L, or any range composed of any two of them. It can also be understood that the endpoint of the pyrolysis reaction is that the concentration of lithium oxide in the pyrolysis mother liquor is 5-8 g / L.

[0059] In the specific implementation process of the present invention, the first precipitate can be washed, and a part of the washing water is incorporated into the first filtrate to adjust the concentration of lithium oxide in the first filtrate to 5-20 g / L, which is convenient for the subsequent reaction steps.

[0060] It should be noted that the present invention uses the concentration of lithium oxide to represent the content of lithium in the solution. In the specific implementation process of the present invention, the concentration of lithium oxide needs to be converted into the concentration of lithium sulfate.

[0061] In order to further improve the quality of lithium carbonate or lithium hydroxide products, processes such as sodium removal by freezing, calcium and magnesium removal by chemical means, calcium and magnesium removal by ion exchange, calcium and magnesium complexation, and calcium and magnesium chelation can be added before, after, or between any steps. For example, in some embodiments, S1 further includes: first subjecting the lithium-containing solution to a freezing treatment to obtain a mixture; after performing a fifth solid-liquid separation on the mixture, obtaining a purified lithium-containing solution and sodium sulfate impurities; mixing the purified lithium-containing solution, an organic acid, and a first calcium-containing compound to form a slurry to be reacted. In this way, the sodium impurities in the lithium-containing solution can be removed by the freezing treatment, and the purity of the lithium-containing solution can be improved.

[0062] The freezing treatment can be one-stage or two-stage freezing. In some embodiments, the freezing treatment includes a first-stage freezing and a second-stage freezing. The temperature of the first-stage freezing is 10-15 °C, and the temperature of the second-stage freezing is 0-5 °C.

[0063] The following further describes the present application in detail with specific embodiments, and these embodiments should not be construed as limiting the scope claimed by the present application.

[0064] Example 1

[0065] The method for preparing a lithium-containing product using a lithium-containing solution in this embodiment includes:

[0066] S1, lithium salt conversion: Add 2.0 tons of bisphenol A to a lithium sulfate solution with a lithium oxide concentration of 21 g / L and a volume of 10 m 3 After mixing evenly, add calcium oxide slurry to it at a rate of 0.15 t / h, and finally the addition amount of calcium oxide is 0.45 t. After the first reaction, a first mixture is obtained; filter the first mixture to obtain calcium sulfate precipitate and a solution containing lithium bisphenolate; perform a first leaching on the calcium sulfate precipitate, and part of the leaching water is incorporated into the lithium bisphenolate solution to adjust the lithium oxide concentration in the solution containing lithium bisphenolate to 15 g / L;

[0067] S2, Mix the solution containing LiT with carbon dioxide gas and react fully at a temperature of 25 °C. The pH value at the end point of the reaction is 9 to obtain a second mixture; after the second mixture is allowed to stand for liquid separation and filtered, a regenerated organic acid and a solution containing LiHCO 3 are obtained; the regenerated organic acid is returned to S1;

[0068] S3, Pyrolyze the solution containing LiHCO 3 at a temperature of 90 °C until the lithium oxide concentration in the solution reaches 6.5 g / L at the end point of the reaction to obtain a Li 2 CO 3 suspension; filter the Li 2 CO 3 suspension to obtain a Li 2 CO 3 crude product and pyrolysis mother liquor;

[0069] S4, Wash the Li 2 CO 3 crude product once and filter it to obtain a Li 2 CO 3 refined product;

[0070] S5, React the Li 2 CO 3 refined product with calcium oxide or calcium hydroxide fully in solution to obtain a fourth mixture; filter the fourth mixture to obtain calcium carbonate precipitate and a LiOH solution; evaporate and crystallize the LiOH solution to obtain lithium hydroxide product.

[0071] Example 2

[0072] The method for preparing a lithium-containing product using a lithium-containing solution in this embodiment includes:

[0073] S1, Perform two-stage freezing treatment on the lithium sulfate solution at 10 °C and 0 °C to remove sodium sulfate, reduce the sodium content in the solution to 15 g / L, and obtain a purified lithium sulfate solution; add to 10 m3 Add 2.7 tons of phenol to the purified lithium sulfate solution with a lithium oxide concentration of 21 g / L. After mixing evenly, add calcium oxide slurry to it at a rate of 0.15 t / h, and finally make the addition amount of calcium oxide be 0.60 t. After the first reaction, a first mixture is obtained; filter the first mixture to obtain calcium sulfate precipitate and a solution containing lithium phenoxide; perform a first leaching on the calcium sulfate precipitate, and part of the leaching water is incorporated into the solution containing lithium phenoxide to adjust the lithium oxide concentration in the solution containing lithium phenoxide to 15 g / L.

[0074] S2. Mix the solution containing lithium phenoxide with carbon dioxide gas and react fully at a temperature of 30 °C. The pH value at the end point of the reaction is 9 to obtain a second mixture; after the second mixture is allowed to stand for liquid separation and filtered, a regenerated organic acid and a solution containing LiHCO 3 are obtained; the regenerated organic acid is returned to S1;

[0075] S3. Pyrolyze the solution containing LiHCO 3 at a temperature of 95 °C until the lithium oxide concentration in the solution reaches 6.5 g / L at the end point of the reaction to obtain a suspension of Li 2 CO 3 ; filter the suspension of Li 2 CO 3 to obtain crude Li 2 CO 3 and pyrolysis mother liquor;

[0076] S4. After washing and filtering the crude Li 2 CO 3 once, obtain refined Li 2 CO 3 ;

[0077] S5. After the refined Li 2 CO 3 reacts fully with calcium oxide or calcium hydroxide in solution, obtain a fourth mixture; filter the fourth mixture to obtain calcium carbonate precipitate and LiOH solution; evaporate and crystallize the LiOH solution to obtain lithium hydroxide product.

[0078] Example 3

[0079] The difference from Example 1 is that in S1, the acidifying agent is replaced by bisphenol S.

[0080] Example 4

[0081] The difference from Example 1 is that in S1, the lithium oxide concentration in the solution containing LiT is adjusted to 5 g / L.

[0082] Example 5

[0083] The difference from Example 1 is that in S1, the concentration of lithium oxide in the solution containing LiT is adjusted to 20 g / L.

[0084] Example 6

[0085] The difference from Example 1 is that in S2, the pH value at the reaction end point is adjusted to 8.

[0086] Example 7

[0087] The difference from Example 1 is that in S2, the pH value at the reaction end point is adjusted to 10.

[0088] Example 8

[0089] The difference from Example 1 is that in S2, the pH value at the reaction end point is adjusted to 11.

[0090] Example 9

[0091] The difference from Example 1 is that in S3, the reaction end point is when the concentration of lithium oxide in the solution is 5 g / L.

[0092] Example 10

[0093] The difference from Example 1 is that in S3, the reaction end point is when the concentration of lithium oxide in the solution is 8 g / L.

[0094] Comparative Example 1

[0095] The difference from Example 1 is that in S1, bisphenol A is replaced with sodium carbonate, and no calcium oxide slurry is added to obtain crude Li 2 CO 3 crude product; S2 and S3 are omitted.

[0096] Comparative Example 2

[0097] The difference from Example 1 is that in S1, bisphenol A is replaced with sodium hydroxide, and no calcium oxide slurry is added.

[0098] Recovery rate of lithium carbonate = mass of Li in crude lithium carbonate / mass of Li in lithium-containing solution;

[0099] Recovery rate of lithium hydroxide = mass of Li in lithium hydroxide / mass of Li in lithium carbonate;

[0100] Inductively coupled plasma optical emission spectrometry (ICP-OES) is used to test and obtain the purity of lithium carbonate in the lithium carbonate product and the purity of lithium hydroxide in the lithium hydroxide product.

[0101] Table 1

[0102]

[0103]

[0104] As can be seen from Table 1, through step-by-step reactions, the present application can effectively extract lithium from a lithium-containing solution, significantly improve the yield of lithium-containing products (lithium carbonate or lithium hydroxide), prepare lithium-containing products with high purity, which can meet the requirements of battery grade, and can recycle organic acids, reduce the consumption of reagents, and lower the production cost.

[0105] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects and do not necessarily describe a specific order or sequence. It should be understood that such terms can be interchanged under appropriate circumstances so that the embodiments of the present application described herein can be implemented in an order other than those described herein.

[0106] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a lithium-containing product using a lithium-containing solution, characterized in that: include: S1, mixing a lithium-containing solution, an organic acid and a first calcium-containing compound to form a slurry to be reacted; the slurry to be reacted undergoes a first reaction to obtain a first mixture; performing a first solid-liquid separation on the first mixture to obtain a first filtrate and a first precipitate; S2, mixing the first filtrate with carbon dioxide to obtain a system to be reacted; the system to be reacted undergoes a second reaction to obtain a second mixed material; and the second mixed material is phase-separated to obtain a regenerated organic acid and a solution containing LiHCO3; S3, subjecting the solution containing LiHCO3 to pyrolysis treatment to obtain a third mixed material; subjecting the third mixed material to a second solid-liquid separation to obtain a lithium carbonate crude product and a pyrolysis mother liquor; Wherein, the pKa value of the organic acid is greater than the pKa value of carbonic acid.

2. The method according to claim 1, characterized in that: Also includes: S4, washing the crude lithium carbonate product and performing a third solid-liquid separation to obtain a refined lithium carbonate product; and / or, The S3 further includes returning the regenerated organic acid to the S1 to mix with the lithium-containing solution and the first calcium-containing compound to form the slurry to be reacted.

3. The method according to claim 2, characterized in that Also includes: S5, mixing the crude lithium carbonate or the refined lithium carbonate, the second calcium-containing compound and water to obtain a mixture to be reacted; subjecting the mixture to be reacted to a third reaction to obtain a fourth mixture; subjecting the fourth mixture to a fourth solid-liquid separation to obtain a calcium carbonate precipitate and a lithium hydroxide solution; and subjecting the lithium hydroxide solution to evaporation and crystallization to obtain a lithium hydroxide product.

4. The method according to any one of claims 1 to 3, characterized in that The organic acid includes at least one of phenol, bisphenol A and bisphenol S.

5. The method according to claim 3, characterized in that: The first calcium-containing compound and the second calcium-containing compound each independently include calcium oxide and / or calcium hydroxide.

6. The method according to any one of claims 1 to 3, characterized in that The lithium-containing solution comprises lithium sulfate; Preferably, the molar ratio of the organic acid to the lithium sulfate in the lithium-containing solution is (0.8-5):1; Preferably, the molar ratio of the first calcium-containing compound to the lithium sulfate in the lithium-containing solution is (0.8-5):

1.

7. The method according to any one of claims 1 to 3, characterized in that The temperature of the first reaction is 30° C. to 95° C., and the time of the first reaction is 0.5 h to 5 h; and / or, The temperature of the second reaction is 10°C to 50°C; and / or, The temperature of the pyrolysis treatment is 80°C to 95°C.

8. The method according to any one of claims 1 to 3, characterized in that The concentration of lithium oxide in the first filtrate is 5 g / L to 20 g / L; and / or, The pH value of the second mixture is 8 to 10; and / or, The concentration of lithium oxide in the pyrolysis mother liquor is 5 g / L to 8 g / L.

9. The method according to any one of claims 1 to 3, characterized in that The S1 also includes: first freezing the lithium-containing solution to obtain a mixture; performing a fifth solid-liquid separation on the mixture to obtain a purified lithium-containing solution and sodium sulfate impurities; and mixing the purified lithium-containing solution, the organic acid and the first calcium-containing compound to form the slurry to be reacted.

10. The method according to claim 9, characterized in that The freezing process includes a first stage of freezing and a second stage of freezing, wherein the temperature of the first stage of freezing is 10°C to 15°C, and the temperature of the second stage of freezing is 0°C to 5°C.

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