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

Abstract

The invention provides a method for preparing a lithium-containing product by using a lithium-containing solution, and relates to the technical field of lithium salt preparation, the method comprises the following steps: S1, introducing ammonia gas and carbon dioxide into water to form a gas-liquid mixed system; carrying out first reaction on the gas-liquid mixed system to obtain an ammonium carbonate solution; s2, mixing the lithium-containing solution with an ammonium carbonate solution to form a to-be-reacted system; after the reaction system is subjected to the second reaction, a first mixture is obtained; and carrying out first solid-liquid separation on the first mixture to obtain ammonium salt mother liquor and a lithium carbonate crude product. According to the method, lithium can be effectively extracted from the lithium-containing solution, and the production cost is reduced.

Description

Technical Field

[0001] This application relates to the technical field of lithium salt preparation. Specifically, it relates to a method for preparing lithium-containing products using lithium-containing solutions. Background Art

[0002] Lithium-containing products such as lithium carbonate and lithium hydroxide are key raw materials for preparing battery cathode materials. Currently, there are mainly two production methods for these lithium-containing products: lithium extraction from brine and lithium extraction from ores. Among them, lithium extraction from brine mainly extracts lithium through evaporation crystallization or extraction methods. The disadvantage of the evaporation crystallization method is high energy consumption and low extraction efficiency. The lithium solution obtained by evaporation crystallization contains impurities such as salts and alkalis, which bring great difficulties to its subsequent treatment. The disadvantage of the extraction method is that the extractant is expensive and has low extraction efficiency, and the extractant is often toxic, flammable, and explosive, and most extractants have low extraction rates for lithium, and the regeneration cost of the extractant is relatively high. Lithium extraction from ores involves leaching 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 lithium carbonate products. There is also a method where sodium hydroxide reacts with the lithium sulfate solution, and after freezing and denitrification and evaporation crystallization to obtain lithium hydroxide, carbon dioxide is then used 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 purpose of this application is to provide a method for preparing lithium-containing products using lithium-containing solutions, so as to solve the problems of low purity and high production cost of lithium-containing products in the existing process of preparing lithium-containing products using lithium-containing solutions.

[0004] To achieve the above purpose, on the one hand, this application provides a method for preparing lithium-containing products using lithium-containing solutions, including:

[0005] S1, introducing ammonia gas and carbon dioxide into water to form a gas-liquid mixing system; after the first reaction of the gas-liquid mixing system, an ammonium carbonate solution is obtained;

[0006] S2, mixing the lithium-containing solution with the ammonium carbonate solution to form a reaction system to be reacted; after the second reaction of the reaction system to be reacted, a first mixture is obtained; the first mixture is subjected to the first solid-liquid separation to obtain an ammonium salt mother liquor and a crude lithium carbonate product.

[0007] Furthermore, it also includes:

[0008] S3, washing and filtering the crude lithium carbonate product to obtain a refined lithium carbonate product;

[0009] S4. Mix the crude lithium carbonate or refined lithium carbonate, the first calcium-containing compound, and water to obtain a slurry to be reacted. After the third reaction of the slurry to be reacted, a second mixture is obtained. After the second solid-liquid separation of the second mixture, calcium carbonate precipitate and lithium hydroxide solution are obtained. Evaporate and crystallize the lithium hydroxide solution to obtain lithium hydroxide product.

[0010] Furthermore, it also includes:

[0011] S5. Mix the ammonium salt mother liquor with the second calcium-containing compound to form a mixture to be reacted. Heat-treat the mixture to be reacted to obtain regenerated ammonia gas and residual liquid. Return the regenerated ammonia gas to S1 to react with carbon dioxide passed into water to form ammonium carbonate solution.

[0012] Furthermore, the first calcium-containing compound and the second calcium-containing compound each independently include calcium oxide and / or calcium hydroxide.

[0013] Furthermore, the lithium-containing solution contains lithium salts, and the lithium salts include lithium sulfate and / or lithium chloride;

[0014] Preferably, the molar ratio of the lithium salt in the lithium-containing solution to the ammonium carbonate in the ammonium carbonate solution is 1.1:(1 - 2).

[0015] Furthermore, the mass concentration of the ammonium carbonate solution is 200 g / L - 400 g / L.

[0016] Furthermore, the temperature of the first reaction is 50°C - 70°C, and the time of the first reaction is 1 h - 2 h; and / or,

[0017] The temperature of the second reaction is 60°C - 70°C, and the time of the second reaction is 2 h - 4 h; and / or,

[0018] The temperature of the third reaction is 50°C - 80°C, and the time of the third reaction is 2 h - 3 h; and / or,

[0019] The temperature of the heat treatment is 95°C - 105°C, and the time of the heat treatment is 2 h - 3 h.

[0020] Furthermore, the volume ratio of ammonia gas to carbon dioxide is (1.5 - 2.5):1.

[0021] Furthermore, S2 also includes: First, freeze-treat the lithium-containing solution to obtain a mixture. After the third solid-liquid separation of the mixture, a purified lithium-containing solution and sodium salt impurities are obtained. Mix the purified lithium-containing solution with the ammonium carbonate solution to form a reaction system to be reacted.

[0022] Furthermore, the freeze-treatment includes a first-stage freeze and a second-stage freeze. The temperature of the first-stage freeze is 10 - 15°C, and the temperature of the second-stage freeze is 0 - 5°C.

[0023] Applying the technical solution of the present application, using ammonium carbonate formed by ammonia and carbon dioxide as a precipitant can not only effectively precipitate lithium ions, but also recover ammonia and carbon dioxide through subsequent treatment, effectively reducing the production cost and improving the resource utilization rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings forming a part of this application are used to provide a further understanding of the present application. The schematic embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation to the present application. In the drawings:

[0025] Figure 1 is a flowchart of a method for preparing a lithium-containing product using a lithium-containing solution in an embodiment of the present application;

[0026] Figure 2 is a flowchart of a method for preparing a lithium-containing product using a lithium-containing solution in another embodiment of the present application;

[0027] Figure 3 is a flowchart of a method for preparing a lithium-containing product using a lithium-containing solution in yet another embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] 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 application will be described in detail below with reference to the embodiments.

[0029] 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:

[0030] S1, introducing ammonia and carbon dioxide into water to form a gas-liquid mixture system; after the first reaction of the gas-liquid mixture system, an ammonium carbonate solution is obtained;

[0031] S2, mixing the lithium-containing solution with the ammonium carbonate solution to form a reaction system to be reacted; after the second reaction of the reaction system to be reacted, a first mixture is obtained; the first mixture is subjected to first solid-liquid separation to obtain an ammonium salt mother liquor and a crude lithium carbonate product.

[0032] The lithium-containing solution in the present application contains a lithium salt. For example, the lithium-containing solution can be a lithium sulfate solution formed by leaching lithium ore, or a lithium chloride solution. At this time, the lithium salt in the lithium-containing solution is lithium sulfate (Li2SO4) or lithium chloride (LiCl).

[0033] In step S1, ammonia (NH3) and carbon dioxide (CO2) are introduced into water to form a gas-liquid mixture system. The first reaction utilizes the chemical properties of ammonia and carbon dioxide to generate ammonium carbonate ((NH4)2CO3) solution in the aqueous phase. The chemical reaction equation for the first reaction is: CO2 + 2NH3 + 2H2O = (NH4)2CO3·H2O.

[0034] In step S2, after the ammonium carbonate solution is formed, it is mixed with a lithium-containing solution to form a reaction system to be reacted. After the second reaction of the reaction system to be reacted, a first mixture is generated. The first mixture contains crude lithium carbonate and an ammonium salt mother liquor. The first solid-liquid separation refers to separating the first mixture by physical means such as filtration to obtain the ammonium salt mother liquor and solid crude lithium carbonate. The ammonium salt mother liquor can be recycled.

[0035] Specifically, when the lithium salt in the lithium-containing solution includes lithium sulfate, the chemical reaction equation for the second reaction is: Li2SO4 + (NH4)2CO3 = Li2CO3 + (NH4)2SO4. When the lithium salt in the lithium-containing solution includes lithium chloride, the chemical reaction equation for the second reaction is: 2LiCl + (NH4)2CO3 = Li2CO3 + 2NH4Cl. When the lithium salt in the lithium-containing solution includes lithium sulfate, the ammonium salt mother liquor contains (NH4)2SO4; when the lithium salt in the lithium-containing solution includes lithium chloride, the ammonium salt mother liquor contains NH4Cl.

[0036] This application uses ammonium carbonate formed by ammonia and carbon dioxide as a precipitant, and can prepare crude lithium carbonate. After further purification, the crude lithium carbonate can be used to produce high-purity lithium carbonate or lithium hydroxide, and can produce high-purity lithium-containing products, meeting the quality standards of battery-grade lithium-containing products. Secondly, this application uses ammonia and carbon dioxide instead of traditional high-cost raw materials such as sodium carbonate or sodium hydroxide, significantly reducing the production cost. Ammonia and carbon dioxide can be prepared from inexpensive raw materials such as ammonium salts and calcium carbonate; in addition, the ammonium salt mother liquor of this application can be reused to achieve safe recycling and further reduce the production cost.

[0037] The crude lithium carbonate can be further processed to obtain a lithium carbonate product with higher purity. In some embodiments, as Figure 2 shown, it further includes: S3, washing the crude lithium carbonate to obtain refined lithium carbonate. Specifically, after washing and filtering the crude lithium carbonate, refined lithium carbonate is obtained. The residual solution is removed by washing, and the washing liquid is separated from the solid phase by filtration. The obtained solid phase is the refined lithium carbonate.

[0038] In some embodiments, it further includes: S4. Mixing the crude lithium carbonate or refined lithium carbonate, the first calcium-containing compound and water to obtain a slurry to be reacted; after the third reaction of the slurry to be reacted, a second mixture is obtained; after the second solid-liquid separation of the second mixture, calcium carbonate precipitate and lithium hydroxide solution are obtained; the lithium hydroxide solution is subjected to evaporation crystallization to obtain a lithium hydroxide product. A high-purity lithium hydroxide product can be obtained through step S4. In the specific implementation process of the present application, lithium-containing products such as crude lithium carbonate, refined lithium carbonate, and lithium hydroxide product can be obtained according to actual needs.

[0039] Specifically, mix the crude lithium carbonate or refined lithium carbonate with the first calcium-containing compound and an appropriate amount of water. Water serves as a reaction medium, enabling lithium carbonate and the first calcium-containing compound to come into full contact and undergo a chemical reaction to form calcium carbonate (CaCO3) precipitate and lithium hydroxide (LiOH) solution, obtaining a second mixture; the second mixture undergoes a second solid-liquid separation to obtain calcium carbonate precipitate and a pure lithium hydroxide solution; the obtained lithium hydroxide solution is subjected to evaporation concentration 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 pyrolyzed or reacted with an acid to prepare carbon dioxide, which is then returned to S1, realizing the reuse of resources, reducing the demand and cost of fresh carbon dioxide, and reducing production costs.

[0040] In some embodiments, the first calcium-containing compound includes calcium oxide (CaO) and / or calcium hydroxide (Ca(OH)2). When the first calcium-containing compound is Ca(OH)2, the chemical reaction equation of the second reaction is: Li2CO3 + Ca(OH)2 = 2LiOH + CaCO3; when the first calcium-containing compound is CaO, the chemical reaction equation of the second reaction is: Li2CO3 + CaO + H2O = 2LiOH + CaCO3.

[0041] In some embodiments, as Figure 3 shown, it further includes: S5. Mixing the ammonium salt mother liquor with the second calcium-containing compound to form a mixture to be reacted; subjecting the mixture to be reacted to heat treatment to obtain recycled ammonia gas and a residual liquid; returning the recycled ammonia gas to S1 to be passed into water together with carbon dioxide to form an ammonium carbonate solution.

[0042] Specifically, the ammonium salt mother liquor (containing ammonium sulfate (NH4)2SO4 or ammonium chloride NH4Cl) in step S2 is mixed with a second calcium-containing compound in a certain proportion to form a reaction-ready mixture. The second calcium-containing compound can convert ammonia gas and acidic components (sulfuric acid or hydrochloric acid) in the ammonium salt into insoluble salts through chemical reactions while releasing ammonia gas. The reaction-ready mixture needs to undergo heat treatment. During the heat treatment process, the mixture reacts under heating conditions to release ammonia gas. The regenerated ammonia gas is returned to step S1 and passed into water together with carbon dioxide to form ammonium carbonate solution again, which is used for the subsequent preparation process of lithium carbonate or lithium hydroxide. This recycling not only reduces the consumption of ammonia gas but also reduces the emission of waste. The residual liquid mainly contains insoluble salts (such as CaSO4 or CaCl2) and water. This part of the liquid can be further processed, such as filtration, evaporation, and crystallization, to recover the calcium salts as by-products or be discharged as industrial wastewater after treatment to ensure compliance with environmental protection standards.

[0043] In some embodiments, the second calcium-containing compound may include calcium oxide (CaO) and / or calcium hydroxide (Ca(OH)2).

[0044] When the second calcium-containing compound is Ca(OH)2, the chemical reaction equation for the heat treatment is:

[0045] (NH4)2SO4 + Ca(OH)2 = 2NH3 + CaSO4 + 2H2O, or,

[0046] 2NH4Cl + Ca(OH)2 = 2NH3 + CaCl2 + 2H2O.

[0047] When the second calcium-containing compound is CaO, the chemical reaction equation for the heat treatment is:

[0048] (NH4)2SO4 + CaO + H2O = 2NH3 + CaSO4 + 2H2O, or,

[0049] 2NH4Cl + CaO + H2O = 2NH3 + CaCl2 + 2H2O.

[0050] The lithium-containing solution contains lithium salts, and the lithium salts include lithium sulfate and / or lithium chloride; in some embodiments, the molar ratio of the lithium salts in the lithium-containing solution to ammonium carbonate in the ammonium carbonate solution is 1.1:(1 - 2), such as 1.1:1, 1.1:1.2, 1.1:1.5, 1.1:1.8, 1.1:2, or any range composed of any two of them.

[0051] In some embodiments, the mass concentration of the ammonium carbonate solution is 200 g / L to 400 g / L, such as 200 g / L, 250 g / L, 300 g / L, 350 g / L, 400 g / L, or the range composed of any two of them; and / or, the volume ratio of ammonia gas to carbon dioxide is (1.5 to 2.5):1, such as 1.5:1, 1.8:1, 2:1, 2.5:1, or the range composed of any two of them.

[0052] In some embodiments, the temperature of the first reaction is 50°C to 70°C, and the time of the first reaction is 1 h to 2 h. By controlling the temperature and reaction time of the first reaction, a highly saturated and stable ammonium carbonate solution can be obtained.

[0053] In some embodiments, the temperature of the second reaction is 60°C to 70°C, and the time of the second reaction is 2 h to 4 h.

[0054] In some embodiments, the temperature of the third reaction is 50°C to 80°C, and the time of the third reaction is 2 h to 3 h.

[0055] In some embodiments, the temperature of the heat treatment is 95°C to 105°C, and the time of the heat treatment is 2 h to 3 h. By limiting the temperature and time of the heat treatment, it is ensured that the ammonium salt decomposes sufficiently and ammonia gas is released. At the same time, the heat treatment also helps to accelerate the evaporation of water and is beneficial to improving the purity of ammonia gas.

[0056] In order to further improve the quality of lithium carbonate or lithium hydroxide products, processes such as freezing to remove sodium, chemical removal of calcium and magnesium, ion exchange removal of calcium and magnesium, complexing of calcium and magnesium, and chelating of calcium and magnesium can be added before, after, or between any steps. In some embodiments, S2 further includes: first, subjecting the lithium-containing solution to a freezing treatment to obtain a mixed material; after performing a third solid-liquid separation on the mixed material, obtaining a purified lithium-containing solution and sodium salt impurities; and mixing the purified lithium-containing solution with the ammonium carbonate solution to form a reaction system to be reacted. In this way, the sodium impurities in the lithium-containing solution can be removed through the freezing treatment, and the purity of the lithium-containing solution can be improved.

[0057] 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 to 15°C, and the temperature of the second-stage freezing is 0 to 5°C.

[0058] 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.

[0059] Example 1

[0060] The method for preparing a lithium-containing product using a lithium-containing solution in this example includes:

[0061] S1. Introduce ammonia and carbon dioxide with a volume ratio of 2:1 into 5 L of water and react at a temperature of 65 °C to obtain an ammonium carbonate solution with a mass concentration of 300 g / L.

[0062] S2. Pass the ammonium carbonate solution into 10 L of lithium sulfate solution to obtain a lithium carbonate suspension; after filtering the lithium carbonate suspension, obtain crude Li₂CO₃ and an ammonium salt mother liquor; among them, the molar ratio of lithium sulfate in the lithium sulfate solution to ammonium carbonate in the ammonium carbonate solution is 1:1.

[0063] S3. Wash the crude Li₂CO₃ product once and filter to obtain refined Li₂CO₃.

[0064] S4. Mix the refined Li₂CO₃ with calcium hydroxide in a solution, fully react to obtain a LiOH solution containing calcium carbonate solid; after filtering the LiOH solution containing calcium carbonate solid, obtain by-product calcium carbonate precipitate and a LiOH solution; after evaporating and crystallizing the LiOH solution, obtain lithium hydroxide product.

[0065] S5. Mix the ammonium salt mother liquor with calcium hydroxide to form a mixture to be reacted; perform heat treatment on the mixture to be reacted at 95 °C for 2 hours to obtain regenerated ammonia and a residual liquid; return the regenerated ammonia to S1 for reacting with carbon dioxide introduced into water to form an ammonium carbonate solution.

[0066] Example 2

[0067] The method for preparing a lithium-containing product using a lithium-containing solution in this example includes:

[0068] S1. Introduce ammonia and carbon dioxide with a volume ratio of 2:1 into 5 L of water and react at a temperature of 60 °C to obtain an ammonium carbonate solution with a mass concentration of 300 g / L.

[0069] S2. Subject the lithium sulfate solution to two-stage freezing treatments at 10 °C and 0 °C in sequence, and after filtering, obtain a purified lithium sulfate solution and sodium sulfate impurities, and the sodium content in the purified lithium sulfate solution is reduced to 2 g / L; pass the ammonium carbonate solution into 10 L of the purified lithium sulfate solution to obtain a lithium carbonate suspension; after filtering the lithium carbonate suspension, obtain crude Li₂CO₃ and an ammonium salt mother liquor; among them, the molar ratio of lithium sulfate in the purified lithium sulfate solution to ammonium carbonate in the ammonium carbonate solution is 1:1.

[0070] S3. Wash the crude Li₂CO₃ product once and filter to obtain refined Li₂CO₃.

[0071] S4. After fully reacting Li₂CO₃ refined product with calcium hydroxide in solution, an LiOH solution containing calcium carbonate solid is obtained; after filtering the LiOH solution containing calcium carbonate solid, by-product calcium carbonate precipitate and LiOH solution are obtained; after evaporative crystallization of the LiOH solution, lithium hydroxide product is obtained.

[0072] S5. Mix the ammonium salt mother liquor with calcium hydroxide to form a mixture to be reacted; perform heat treatment on the mixture to be reacted at 95 °C for 2 hours to obtain regenerated ammonia gas and residual liquid; return the regenerated ammonia gas to S1 for reacting with carbon dioxide introduced into water to form ammonium carbonate solution.

[0073] Example 3

[0074] The method for preparing a lithium-containing product using a lithium-containing solution in this example includes:

[0075] S1. Introduce ammonia gas and carbon dioxide with a volume ratio of 2:1 into 5 L of water and react at a temperature of 60 °C to obtain an ammonium carbonate solution with a mass concentration of 300 g / L;

[0076] S2. Pass the ammonium carbonate solution into 8 L of lithium sulfate solution to obtain a lithium carbonate suspension; after filtering the lithium carbonate suspension, Li₂CO₃ crude product and ammonium salt mother liquor are obtained; among them, the molar ratio of lithium sulfate in the purified lithium sulfate solution to ammonium carbonate in the ammonium carbonate solution is 1.1:2;

[0077] S3. After washing and filtering the Li₂CO₃ crude product once, Li₂CO₃ refined product is obtained;

[0078] S4. Mix Li₂CO₃ refined product with calcium hydroxide in solution, and after fully reacting, an LiOH solution containing calcium carbonate solid is obtained; after filtering the LiOH solution containing calcium carbonate solid, by-product calcium carbonate precipitate and LiOH solution are obtained; after evaporative crystallization of the LiOH solution, lithium hydroxide product is obtained;

[0079] S5. Mix the ammonium salt mother liquor with calcium hydroxide to form a mixture to be reacted; perform heat treatment on the mixture to be reacted at 95 °C for 2 hours to obtain regenerated ammonia gas and residual liquid; return the regenerated ammonia gas to S1 for reacting with carbon dioxide introduced into water to form ammonium carbonate solution.

[0080] Example 4

[0081] The method for preparing a lithium-containing product using a lithium-containing solution in this example includes:

[0082] S1. Introduce ammonia gas and carbon dioxide with a volume ratio of 2:1 into 5 L of water and react at a temperature of 70 °C to obtain an ammonium carbonate solution with a mass concentration of 300 g / L;

[0083] S2. Introduce an ammonium carbonate solution into an 8 L lithium sulfate solution to obtain a lithium carbonate suspension. After filtering the lithium carbonate suspension, a crude lithium carbonate product and an ammonium salt mother liquor are obtained. Among them, the molar ratio of lithium sulfate in the purified lithium sulfate solution to ammonium carbonate in the ammonium carbonate solution is 1.1:2.

[0084] S3. After washing the crude lithium carbonate product once and filtering, a refined lithium carbonate product is obtained.

[0085] S4. Mix the refined lithium carbonate product with calcium hydroxide in a solution. After a full reaction, a lithium hydroxide solution containing calcium carbonate solid is obtained. After filtering the lithium hydroxide solution containing calcium carbonate solid, a by-product calcium carbonate precipitate and a lithium hydroxide solution are obtained. After evaporative crystallization of the lithium hydroxide solution, a lithium hydroxide product is obtained.

[0086] S5. Mix the ammonium salt mother liquor with calcium hydroxide to form a mixture to be reacted. Heat-treat the mixture to be reacted at 95 °C for 2 hours to obtain regenerated ammonia gas and a residual liquid. Return the regenerated ammonia gas to S1 for reacting with carbon dioxide introduced into water to form an ammonium carbonate solution.

[0087] Example 5

[0088] The method for preparing a lithium-containing product using a lithium-containing solution in this example includes:

[0089] S1. Introduce ammonia gas and carbon dioxide with a volume ratio of 2.5:1 into 5 L of water and react at a temperature of 65 °C to obtain an ammonium carbonate solution with a mass concentration of 300 g / L.

[0090] S2. Introduce the ammonium carbonate solution into a 10 L lithium sulfate solution to obtain a lithium carbonate suspension. After filtering the lithium carbonate suspension, a crude lithium carbonate product and an ammonium salt mother liquor are obtained. Among them, the molar ratio of lithium sulfate in the lithium sulfate solution to ammonium carbonate in the ammonium carbonate solution is 1:1.

[0091] S3. After washing the crude lithium carbonate product once and filtering, a refined lithium carbonate product is obtained.

[0092] S4. Mix the refined lithium carbonate product with calcium hydroxide in a solution. After a full reaction, a lithium hydroxide solution containing calcium carbonate solid is obtained. After filtering the lithium hydroxide solution containing calcium carbonate solid, a by-product calcium carbonate precipitate and a lithium hydroxide solution are obtained. After evaporative crystallization of the lithium hydroxide solution, a lithium hydroxide product is obtained.

[0093] S5. Mix the ammonium salt mother liquor with calcium hydroxide to form a reaction mixture to be reacted; subject the reaction mixture to heat treatment at 95 °C for 2 hours to obtain regenerated ammonia gas and a residual liquid; return the regenerated ammonia gas to S1 for use in reacting with carbon dioxide passed into water to form an ammonium carbonate solution.

[0094] Comparative Example 1

[0095] S1. Dissolve solid sodium carbonate in 5 L of water to prepare a sodium carbonate solution with a mass concentration of 300 g / L.

[0096] S2. Add the sodium carbonate solution to 10 L of lithium sulfate solution, stir and react to form a mixture of lithium carbonate precipitate and sodium sulfate; after filtering the mixture, obtain crude lithium carbonate and a sodium sulfate mother liquor.

[0097] S3. Wash the crude lithium carbonate once and filter to obtain refined lithium carbonate.

[0098] S4. Separate the sodium sulfate by-product from the sodium sulfate mother liquor through evaporation and concentration, cooling and crystallization, and return the remaining mother liquor to S1 for recycling.

[0099] Comparative Example 2

[0100] S1. Mix 5 L of sodium hydroxide solution with 5 L of lithium sulfate solution to react and form a mixed solution of lithium hydroxide and sodium sulfate.

[0101] S2. Cool the reaction solution to 0 °C for freeze denitrification to precipitate sodium sulfate crystals; after filtration, obtain the sodium sulfate by-product and a lithium hydroxide solution.

[0102] S3. Evaporate and concentrate the lithium hydroxide solution to a saturated state, and obtain crude lithium hydroxide after cooling and crystallization.

[0103] S4. Dissolve the crude lithium hydroxide in water, pass in carbon dioxide gas, react to form lithium carbonate precipitate and a lithium hydroxide mother liquor; after filtration, obtain lithium carbonate product and mother liquor.

[0104] S5. Return the mother liquor to S4 for recycling to improve the utilization rate of lithium.

[0105] Recovery rate of lithium carbonate = mass of Li in the crude lithium carbonate product / mass of Li in the lithium-containing solution

[0106] Recovery rate of lithium hydroxide = mass of Li in the lithium hydroxide product / mass of Li in the lithium carbonate product;

[0107] Use inductively coupled plasma optical emission spectrometry (ICP-OES) 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.

[0108] Table 1

[0109]

[0110]

[0111] As can be seen from Table 1, ammonium carbonate formed from ammonia and carbon dioxide is used as a precipitant in this application, which can effectively precipitate lithium ions and effectively improve the yield of lithium-containing products. In addition, ammonia and carbon dioxide can be recovered through subsequent treatment, effectively reducing the production cost and improving the resource utilization

[0112] It should be noted that the terms "first", "second", etc. in the description and claims of this application are used to distinguish similar objects and do not necessarily have to be used to describe a specific order or sequence. It should be understood that such terms can be interchanged under appropriate circumstances so that the embodiments of this application described here can be implemented in an order other than those described here, for example

[0113] The above are only the preferred embodiments of this application and are not intended to limit this application. For those skilled in the art, various changes and modifications can be made to this application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this application shall be included within the protection scope of this application

Claims

1. A method for preparing a lithium-containing product using a lithium-containing solution, characterized in that, Including: S1, introducing ammonia gas and carbon dioxide into water to form a gas-liquid mixing system; after the first reaction of the gas-liquid mixing system, an ammonium carbonate solution is obtained; S2, mixing a lithium-containing solution with the ammonium carbonate solution to form a reaction system to be reacted; after the second reaction of the reaction system to be reacted, a first mixture is obtained; the first mixture is subjected to first solid-liquid separation to obtain an ammonium salt mother liquor and a crude lithium carbonate product.

2. The method according to claim 1, wherein Also including: S3, washing and filtering the crude lithium carbonate product to obtain a refined lithium carbonate product; S4, mixing the crude lithium carbonate product or the refined lithium carbonate product, a first calcium-containing compound and water to obtain a reaction slurry to be reacted; after the third reaction of the reaction slurry to be reacted, a second mixture is obtained; the second mixture is subjected to second solid-liquid separation to obtain calcium carbonate precipitate and a lithium hydroxide solution; The lithium hydroxide solution is subjected to evaporation crystallization to obtain a lithium hydroxide product.

3. The method according to claim 2, wherein Also including: S5, mixing the ammonium salt mother liquor with a second calcium-containing compound to form a reaction mixture to be reacted; subjecting the reaction mixture to heat treatment to obtain regenerated ammonia gas and a residual liquid; Returning the regenerated ammonia gas to S1 to introduce the carbon dioxide into the water to form the ammonium carbonate solution.

4. 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.

5. The method according to any one of claims 1 to 4, characterized in that, The lithium-containing solution contains a lithium salt, and the lithium salt includes lithium sulfate and / or lithium chloride; Preferably, the molar ratio of the lithium salt in the lithium-containing solution to ammonium carbonate in the ammonium carbonate solution is 1.1:(1-2).

6. The method according to any one of claims 1 to 4, characterized in that, The mass concentration of the ammonium carbonate solution is 200 g / L to 400 g / L.

7. The method according to claim 4, characterized in that, The temperature of the first reaction is 50°C to 70°C, and the time of the first reaction is 1 h to 2 h; and / or, The temperature of the second reaction is 60°C to 70°C, and the time of the second reaction is 2 h to 4 h; and / or, The temperature of the third reaction is 50°C to 80°C, and the time of the third reaction is 2 h to 3 h; and / or, The temperature of the heat treatment is 95°C to 105°C, and the time of the heat treatment is 2 h to 3 h.

8. The method according to any one of claims 1 to 4, characterized in that The volume ratio of the ammonia gas to the carbon dioxide is (1.5-2.5):

1.

9. The method according to any one of claims 1 to 4, characterized in that, S2 also includes: first, subjecting the lithium-containing solution to freezing treatment to obtain a mixture; subjecting the mixture to third solid-liquid separation to obtain a purified lithium-containing solution and sodium salt impurities; mixing the purified lithium-containing solution with the ammonium carbonate solution to form the reaction system to be reacted.

10. The method according to claim 9, characterized in that, 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.

Images