Method for recovering lithium, lithium material recovered and recovery system

Abstract

This application relates to the field of lithium battery recycling technology and provides a method for recovering lithium, comprising: providing waste lithium battery cathode material; mixing the waste lithium battery cathode material with concentrated sulfuric acid and partially reacting it to obtain a mixed acid material; calcining the mixed acid material sequentially at a first temperature and a second temperature to obtain a calcined material, wherein the second temperature is higher than the first temperature; leaching the calcined material with water and filtering it to obtain a lithium-containing solution; and purifying the lithium-containing solution to obtain recovered lithium material. The lithium recovery method provided by this application can achieve efficient and selective leaching of lithium and reduce the content of other metals in the leached lithium-containing solution, thereby reducing the cost of subsequent purification.

Description

Technical Field

[0001] This application belongs to the field of lithium battery recycling technology, and in particular relates to a method for recycling lithium, the recovered lithium material, and a recycling system. Background Technology

[0002] With the widespread use of portable electronic devices and electric vehicles, the consumption of lithium batteries is constantly increasing. However, the lifespan of lithium batteries is only 3-7 years, and a large number of lithium batteries have reached their end-of-life in recent years. Waste lithium batteries contain volatile and easily decomposed fluorinated electrolytes, as well as heavy metals such as copper, cobalt, nickel, and manganese. If not properly disposed of, they can easily cause environmental problems and harm human health. Furthermore, waste lithium batteries also contain valuable lithium. As an important valuable and strategic resource, recycling lithium from waste lithium batteries can alleviate my country's dependence on imported raw materials, stabilize raw material price fluctuations, and reduce environmental pollution, making it a crucial part of the development of the new energy industry.

[0003] Existing methods for recovering lithium from spent lithium batteries typically introduce a large amount of metal impurities, leading to high purification costs during the lithium recovery process. Therefore, it is necessary to develop a new recovery method to reduce purification costs. Summary of the Invention

[0004] The purpose of this application is to provide a method for recovering lithium, the recovered lithium material, and a recovery system, aiming to solve the problem of high purification costs in the lithium recovery process.

[0005] To achieve the above-mentioned objectives, the technical solution adopted in this application is as follows:

[0006] In a first aspect, this application provides a method for recovering lithium, comprising: providing waste lithium battery cathode material; mixing the waste lithium battery cathode material with concentrated sulfuric acid and partially reacting to obtain a mixed acid material; sequentially calcining the mixed acid material at a first temperature and a second temperature to obtain a calcined material, wherein the second temperature is higher than the first temperature; leaching the calcined material with water and filtering it to obtain a lithium-containing solution; and purifying the lithium-containing solution to obtain recovered lithium material.

[0007] Optionally, providing waste lithium battery cathode material includes: preparing waste lithium battery cathode material such that the carbon content in the waste lithium battery cathode material is 5wt%-30wt% and the lithium content is 0.5wt%-6.5wt%.

[0008] Optionally, the concentration of the concentrated sulfuric acid is 70 wt% to 100 wt%.

[0009] Optionally, in the mixed acid material, the mass ratio of concentrated sulfuric acid to the waste lithium battery cathode material is 0.3 to 1.5.

[0010] Optionally, before roasting the mixed acid material, the mixture may be further subjected to crushing treatment so that the particle size of the material in the mixed acid material is less than 3 cm.

[0011] Optionally, before calcining the mixed acid material, the mixture is further subjected to a first stirring treatment for a first duration.

[0012] Optionally, the first temperature is 150℃~680℃, and the roasting treatment is carried out at the first temperature until the sulfur dioxide content in the roasting atmosphere is greater than 0.05v.

[0013] Optionally, the second temperature is 650℃~850℃, and the roasting treatment is carried out at the second temperature until the sulfur dioxide content in the roasting atmosphere is less than 10v and the oxygen content is less than 15v.

[0014] Optionally, before leaching the roasted material with water, the roasted material is further subjected to crushing treatment so that the particle size of the material in the roasted material is less than 0.5 cm.

[0015] Optionally, the recovered lithium material includes lithium carbonate, and the purification treatment of the lithium-containing solution includes: adding a carbonate solution to the lithium-containing solution, precipitating and separating the lithium carbonate.

[0016] Optionally, the recovered lithium material includes lithium phosphate, and the purification treatment of the lithium-containing solution includes: adding a phosphate solution to the lithium-containing solution, precipitating and separating to obtain the lithium phosphate.

[0017] Secondly, this application provides a lithium recycling material, which is prepared by the lithium recycling method provided in the first aspect of this application.

[0018] Thirdly, this application provides a lithium recycling system, comprising: a mixing device for mixing and partially reacting waste lithium battery cathode material with concentrated sulfuric acid to obtain a mixed acid material; a roasting device for roasting the mixed acid material sequentially at a first temperature and a second temperature to obtain a roasted material, wherein the second temperature is higher than the first temperature; a leaching device for leaching the roasted material with water to obtain a leachate; a filtration device for filtering the leachate to obtain a lithium-containing solution; and a purification device for purifying the lithium-containing solution to obtain recycled lithium material.

[0019] The lithium recovery method provided in the first aspect of this application firstly utilizes waste lithium battery cathode material mixed with concentrated sulfuric acid to spontaneously undergo an exothermic reaction, causing some of the cathode active material in the waste lithium battery cathode material to be converted into sulfate. Then, it is sequentially calcined at a lower first temperature and a higher second temperature. The calcination at the lower first temperature converts lithium in different chemical states into lithium sulfate, while the calcination at the higher second temperature converts sulfates of other metals into metal oxides that are insoluble in water. This achieves efficient and selective leaching of lithium and reduces the content of other metals in the lithium-containing solution obtained from the leaching, thereby reducing the cost of subsequent purification.

[0020] The recycled lithium material provided in the second aspect of this application has low impurity content and high purity.

[0021] The lithium recovery system provided in the third aspect of this application has the advantages of high recovery rate and low purification cost in recovering lithium from waste lithium battery cathode materials, as well as short process flow, low cost, modularity, easy scaling and wide applicability of raw materials. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a flowchart of a lithium recovery method provided in an embodiment of this application. Detailed Implementation

[0024] To make the technical problems, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0025] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0026] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0027] It should be understood that in the various embodiments of this application, the order of the above processes does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0028] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0029] The weights of the relevant components mentioned in the embodiments of this application can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this application is within the scope disclosed in the embodiments of this application. Specifically, the mass described in the embodiments of this application can be a mass unit known in the chemical industry, such as μg, mg, g, or kg.

[0030] The terms "first" and "second" are used for descriptive purposes only, to distinguish objects, such as substances, from one another, and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. For example, without departing from the scope of the embodiments of this application, "first XX" may also be referred to as "second XX," and similarly, "second XX" may also be referred to as "first XX." Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of that feature.

[0031] To address the high purification costs in existing lithium recovery methods, please refer to [link / reference needed]. Figure 1 The first aspect of this application provides a method for recovering lithium, comprising:

[0032] S10: Provides cathode materials for spent lithium batteries;

[0033] S20: Waste lithium battery cathode material is mixed with concentrated sulfuric acid and partially reacted to obtain mixed acid material;

[0034] S30: The mixed acid material is roasted sequentially at a first temperature and a second temperature to obtain roasted material, wherein the second temperature is higher than the first temperature;

[0035] S40: The calcined material is leached with water and filtered to obtain a lithium-containing solution;

[0036] S50: Purify the lithium-containing solution to obtain recovered lithium material.

[0037] In step S10 above, the spent lithium battery cathode material contains a carbon source and a cathode active material. Common lithium battery cathode active materials include lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, lithium iron phosphate, lithium iron manganese phosphate, lithium nickel cobalt oxide, lithium nickel cobalt manganese oxide, and lithium nickel cobalt aluminum oxide. This means that the spent lithium battery cathode material contains not only lithium and carbon, but also metal elements such as cobalt, nickel, iron, aluminum, or manganese, depending on the type of cathode active material used in the lithium battery. For easier understanding, LiMO2 will be used to represent the cathode active material below, where M represents other metals besides Li in the cathode active material, including one or more of Co, Ni, Mn, Fe, and Al.

[0038] In step S20 above, the following main reaction occurs:

[0039] 2H2SO4(l)+C(s)=CO2(g)+2SO2(g)+2H2O(g)

[0040] LiMO2(s)+H2SO4(l)=Li2SO4(s)+MSO4(s)+H2O(g)+O2(g)

[0041] During sulfation, concentrated sulfuric acid reacts with carbon to produce carbon dioxide, sulfur dioxide, and water; concentrated sulfuric acid also reacts with some positive electrode active materials to produce sulfates, water, and oxygen.

[0042] In step S30 above, the following main reaction occurs:

[0043] MSO4(s)+C(s)=CO2(g)+2SO2(g)+MO(s)

[0044] 2LiMO2(s)+SO2(g)=Li2SO4(s)+2MO(s)

[0045] CO2(g) + C(s) = 2CO(g)

[0046] 4LiMO2(s)+C(s)=Li2CO3(s)+4MO(s)+Li2O(s)

[0047] During the roasting process, a portion of the MSO4 generated during sulfation reacts with carbon at the first temperature to produce oxides (MO), carbon dioxide, and sulfur dioxide. The released sulfur dioxide further reacts with unreacted LiMO2, the positive electrode active material in the spent lithium-ion battery cathode material, to yield lithium sulfate and oxides (MO). As the roasting temperature increases, during the second temperature roasting, a portion of the MSO4 generated during sulfation continues to react with carbon to produce oxides (MO), carbon dioxide, and sulfur dioxide. The released sulfur dioxide then reacts with unreacted LiMO2, the positive electrode active material in the spent lithium-ion battery cathode material, to yield lithium sulfate and oxides (MO). Simultaneously, with increasing temperature, solid carbon in the spent lithium-ion battery cathode material reacts with carbon dioxide to generate carbon monoxide gas. Furthermore, under high temperature, LiMO2 reacts with carbon to produce lithium carbonate, oxides (MO), and lithium oxide. Here, MO represents oxides of other metals and does not necessarily indicate a 1:1 molar ratio of metal to oxygen in the oxide.

[0048] In step S40 above, the following main reaction occurs:

[0049] Li₂SO₄(s) = Li₂SO₄(l)

[0050] MSO4(s) = MSO4(l)

[0051] Li2CO3(s)+MSO4(l)=Li2SO4(l)+MCO3(s)

[0052] During the leaching process, lithium sulfate generated during roasting dissolves in water, and unconverted MSO4 also dissolves in water and reacts with lithium carbonate generated during roasting to form insoluble carbonate MCO3. Most of the oxides MO generated during roasting are insoluble in water.

[0053] The lithium recovery method provided in the first aspect of this application firstly utilizes waste lithium battery cathode material mixed with concentrated sulfuric acid to spontaneously undergo an exothermic reaction, causing some of the cathode active material in the waste lithium battery cathode material to be converted into sulfate. Then, it is sequentially subjected to gradient calcination at a lower first temperature and a higher second temperature. Calcination at the lower first temperature converts lithium in different chemical states into lithium sulfate, while calcination at the higher second temperature converts sulfates of other metals into metal oxides that are insoluble in water. This achieves efficient and selective leaching of lithium and reduces the content of other metals in the lithium-containing solution obtained from the leaching, thereby reducing the cost of subsequent purification.

[0054] In some embodiments, in step S10, providing waste lithium battery cathode material includes: preparing waste lithium battery cathode material such that the carbon content in the waste lithium battery cathode material is 5wt%-30wt% and the lithium content is 0.5wt%-6.5wt%.

[0055] Different lithium batteries typically have different cathode material formulations, resulting in different cathode materials from spent lithium batteries. By analyzing different spent lithium battery cathode materials to determine their composition, and then mixing these materials in a specific ratio, a target-ratio spent lithium battery cathode material can be obtained.

[0056] In practice, it has been found that the carbon and lithium content in waste lithium battery cathode materials is crucial. Controlling these contents is essential for achieving optimal results, as the carbon content affects the atmosphere during the roasting process, while the lithium content influences the lithium recovery rate. This embodiment achieves a lithium recovery rate of 90%-99% and a lithium leaching rate more than 25 times that of cobalt and nickel by controlling the carbon content of the waste lithium battery cathode material to 5wt%-30wt% and the lithium content to 0.5wt%-6.5wt%.

[0057] Optionally, the carbon content in the waste lithium battery cathode material is 5wt%, 5.5wt%, 7wt%, 8wt%, 10wt%, 13wt%, 15wt%, 18wt%, 20wt%, 25wt%, 28wt%, or 30wt%.

[0058] Optionally, the lithium content in the waste lithium battery cathode material is 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.6wt%, 5wt%, 5.2wt%, 5.8wt%, 6wt%, or 6.5wt%.

[0059] In some embodiments, in step S20, the concentration of concentrated sulfuric acid is 70 wt% to 100 wt%.

[0060] In this embodiment, by controlling the sulfuric acid concentration, the temperature during the reaction process can be controlled, which is beneficial to promoting the sulfation reaction and improving the lithium yield.

[0061] Optionally, the concentration of concentrated sulfuric acid is 70 wt%, 73 wt%, 77 wt%, 80 wt%, 85 wt%, 90 wt%, 93 wt%, 95 wt%, 97 wt%, 98.5 wt%, or 100 wt%.

[0062] In some embodiments, step S20 further includes: separating water vapor from the dust-laden flue gas during the mixing process of concentrated sulfuric acid and waste lithium battery cathode materials and collecting the dust.

[0063] This embodiment collects dust from the smoke and fumes, which is beneficial for recovering valuable elements.

[0064] In some embodiments, in step S20, the mass ratio of concentrated sulfuric acid to waste lithium battery cathode material in the mixed acid mixture is 0.3 to 1.5.

[0065] This embodiment controls the ratio of sulfuric acid to waste lithium battery cathode material, which is beneficial to promote the sulfation reaction. Complete sulfation is achieved by the self-exothermic reaction between concentrated sulfuric acid and waste lithium battery cathode material, that is, all concentrated sulfuric acid reacts with waste lithium battery cathode material. Therefore, it is not necessary to roast in an oxygen atmosphere for a certain period of time, which reduces equipment requirements, reduces energy consumption, and makes it easier to achieve large-scale production.

[0066] Optionally, the mass ratio of concentrated sulfuric acid to waste lithium battery cathode material is 0.3, 0.4, 0.5, 0.6, 0.65, 0.7, 0.9, 1.0, 1.2, 1.3 or 1.5.

[0067] In some embodiments, before calcining the mixed acid material, step S20 further includes crushing the mixed acid material so that the particle size of the material in the mixed acid material is less than 3 cm.

[0068] This embodiment improves the mass transfer efficiency of the roasting process, increases the lithium leaching rate, and reduces the risk of material clogging the equipment by reducing the particle size of the crushed material.

[0069] Optionally, the particle size of the material in the crushed acid mixture is 0.1cm, 0.2cm, 0.4cm, 0.8cm, 1.2cm, 1.5cm, 2cm, 2.5cm or 3cm.

[0070] In some embodiments, before calcining the mixed acid material, step S20 further includes stirring the mixed acid material for a first duration.

[0071] In this embodiment, stirring the mixed acid material facilitates a more complete sulfation reaction and reduces the water content in the material, thus preventing corrosion of the roasting equipment. At the same time, stirring also allows the sulfates produced during sulfation to mix more evenly with the carbon in the waste lithium battery cathode material, thereby controlling the atmosphere during the roasting process and improving the lithium yield.

[0072] Optionally, the first duration is 10 min, 20 min, 30 min, 40 min, 50 min, or 60 min.

[0073] In some embodiments, in step S30, the first temperature is 150°C to 680°C, and the calcination process is carried out at the first temperature until the sulfur dioxide content in the calcination atmosphere is greater than 0.05v.

[0074] The roasting process is carried out in a roasting furnace. Roasting is first performed at a lower initial temperature, then the temperature is increased to a second temperature for continued roasting. During roasting at the first temperature, some easily decomposable salts in the MSO4 generated during sulfation react with carbon during roasting and are converted into oxides (MO), simultaneously releasing carbon dioxide and sulfur dioxide. As the sulfur dioxide content in the roasting atmosphere increases, the positive electrode active material LiMO2 reacts with sulfur dioxide to form lithium sulfate and oxides (MO). This embodiment uses low-temperature, high-sulfur roasting to convert Li in the positive electrode active material LiMO2 into easily soluble lithium sulfate, while converting other impurity metals into insoluble oxides (MO), thereby improving the lithium leaching rate and inhibiting impurity leaching, making it easier to control product quality and facilitating industrial-scale production.

[0075] Optionally, the first temperature is 150°C, 190°C, 200°C, 300°C, 400°C, 450°C, 500°C, 600°C, or 680°C.

[0076] Optionally, the sulfur dioxide content in the calcination atmosphere at the first temperature is 0.05v%, 0.1v%, 0.2v%, 0.23v%, 0.25v%, 0.3v%, 0.5v%, 2v%, 10v%, 15v%, or 30v%.

[0077] In some embodiments, in step S30, the second temperature is 650°C to 850°C, and the calcination process is carried out at the second temperature until the sulfur dioxide content in the calcination atmosphere is less than 10% and the oxygen content is less than 15%.

[0078] During the roasting process at the second temperature, some of the recalcitrant salts in the MSO4 generated during sulfation react with carbon during roasting at the second temperature and are converted into oxides (MO), simultaneously releasing carbon dioxide and sulfur dioxide. The sulfur dioxide continues to react with the positive electrode active material LiMO2, converting into lithium sulfate and oxides (MO). As roasting progresses, the amount of MSO4 decreases while sulfur dioxide is continuously consumed, reducing the sulfur dioxide content in the roasting atmosphere. Under high temperature, the positive electrode active material LiMO2 continues to react with carbon to generate lithium carbonate, oxides (MO), and lithium oxide. This embodiment uses high-temperature, low-sulfur roasting to convert Li in the positive electrode active material LiMO2 into lithium carbonate and lithium oxide, while further converting other impurity metals into insoluble oxides (MO), thereby improving the lithium leaching rate and inhibiting impurity leaching, making it easier to control product quality and facilitating industrial production. Furthermore, in the roasting process of this application, it is not necessary to introduce oxygen into the roasting furnace. During roasting, the oxygen in the air inside the furnace is consumed at high temperatures, thus reducing the oxygen content in the roasting atmosphere.

[0079] Optionally, the second temperature is 650°C, 680°C, 700°C, 750°C, 800°C, or 850°C.

[0080] Optionally, the sulfur dioxide content in the calcination atmosphere at the second temperature is 0 v%, 0.001 v%, 0.05 v%, 0.1 v%, 0.5 v%, 1.0 v%, 4.0 v%, 6.0 v%, 8.0 v% or 10.0 v%.

[0081] Optionally, the oxygen content in the calcination atmosphere at the second temperature is 0.01v%, 0.1v%, 3v%, 5v%, 10v%, 12v%, or 15v%.

[0082] In some embodiments, in step S40, before leaching the calcined material with water, the calcined material is further subjected to crushing treatment so that the particle size of the material in the calcined material is less than 0.5 cm.

[0083] In this embodiment, the particle size of the roasted material is reduced by crushing, which facilitates full contact between the material and water and improves the lithium leaching rate.

[0084] Optionally, the particle size of the material in the calcined feed after crushing is 0.1cm, 0.2cm, 0.3cm, 0.4cm or 0.5cm.

[0085] In some embodiments, in step S40, obtaining a lithium-containing solution by leaching and filtering the calcined material with water includes crushing the calcined material, leaching it with water, and then pressing and filtering it to obtain a lithium-containing solution and filter residue. Here, the filter residue mainly consists of insoluble substances in the calcined material.

[0086] In some embodiments, the recovered lithium material includes lithium carbonate, and the purification treatment of the lithium-containing solution in step S50 includes: adding a carbonate solution to the lithium-containing solution, precipitating and separating to obtain lithium carbonate.

[0087] In this embodiment, a carbonate solution is added to a lithium-containing solution. The carbonate ions combine with the lithium ions to form lithium carbonate, which has a lower solubility than lithium sulfate. The lithium carbonate is then collected through separation.

[0088] Optionally, the carbonate includes at least one of sodium carbonate, sodium bicarbonate, potassium carbonate, and potassium bicarbonate.

[0089] Optionally, before adding the carbonate solution to the lithium-containing solution, the pH value of the lithium-containing solution is adjusted to remove impurities such as Co, Ni, and Mn.

[0090] In some embodiments, the recovered lithium material includes lithium phosphate, and the purification treatment of the lithium-containing solution in step S50 includes: adding a phosphate solution to the lithium-containing solution, precipitating and separating to obtain lithium phosphate.

[0091] In this embodiment, a phosphate solution is added to a lithium-containing solution. The phosphate ions combine with the lithium ions to form lithium phosphate, which has a lower solubility than lithium sulfate. The lithium phosphate is then collected through separation.

[0092] Optionally, the phosphate includes at least one of sodium phosphate, sodium hydrogen phosphate, potassium phosphate, and potassium hydrogen phosphate.

[0093] Optionally, before adding the phosphate solution to the lithium-containing solution, the pH value of the lithium-containing solution is adjusted to remove impurities such as Co, Ni, and Mn.

[0094] The second aspect of this application provides a lithium recovery material, which is prepared by the lithium recovery method provided in the first aspect of this application.

[0095] The recycled lithium material provided in the second aspect of the embodiments of this application has low impurity content and high purity.

[0096] A third aspect of this application provides a lithium recovery system, comprising: a mixing device for mixing and partially reacting waste lithium battery cathode material with concentrated sulfuric acid to obtain a mixed acid material; a roasting device for roasting the mixed acid material sequentially at a first temperature and a second temperature to obtain a roasted material, wherein the second temperature is higher than the first temperature; a leaching device for leaching the roasted material with water to obtain a leachate; a filtration device for filtering the leachate to obtain a lithium-containing solution; and a purification device for purifying the lithium-containing solution to obtain recovered lithium material.

[0097] The lithium recovery system provided in the third aspect of this application has the advantages of high recovery rate and low purification cost in recovering lithium from waste lithium battery cathode materials, as well as short process flow, low cost, modularity, easy scaling, and wide applicability of raw materials.

[0098] The following description is based on specific embodiments.

[0099] Example 1

[0100] S1: Mix battery black powder (i.e. waste lithium battery cathode material) of different compositions in a certain proportion. After mixing, the C content in the battery black powder is 5.7wt% and the Li content is 3.8wt%.

[0101] S2: The battery black powder with the above proportions is mixed with concentrated sulfuric acid in a certain ratio to obtain mixed acid powder. The concentration of concentrated sulfuric acid is 87wt%, and the amount added is 0.48 tons of H2SO4 / ton of black powder. Water vapor in the dust-containing flue gas during the mixing process is separated and dust is collected. The mixed acid powder is crushed before calcination. After crushing, the particle size of the powder is less than 3cm. The crushed mixed acid powder is stirred for 20 minutes before calcination.

[0102] S3: Mix the mixed acid powder with dust and then calcine it under low temperature and high temperature conditions to obtain calcined material; wherein the low temperature condition is 240℃ and the sulfur dioxide content is 0.3v%; the high temperature condition is 650℃ and the sulfur dioxide content is 3v% and the oxygen content is 1v%.

[0103] S4: The calcined material is crushed and leached with water. After pressure filtration, a lithium-containing solution and filter residue are obtained. The particle size of the crushed calcined material is less than 0.5 cm, the lithium leaching rate is 93%, and the contents of Co, Ni and Mn in the lithium-containing solution are 0.12 g / L, 0.05 g / L and 2.1 g / L, respectively.

[0104] S5: After adjusting the pH of the lithium-containing solution to remove impurities such as Co, Ni, and Mn, add sodium carbonate solution and precipitate to obtain lithium carbonate product.

[0105] Example 2

[0106] S1: Mix the battery black powders of different compositions in a specific ratio. After mixing, the C content in the battery black powder is 26.2 wt% and the Li content is 0.9 wt%.

[0107] S2: The battery black powder with the above proportions is mixed with concentrated sulfuric acid in a certain ratio to obtain mixed acid powder. The concentration of concentrated sulfuric acid is 98wt%, and the amount added is 0.35 tons of H2SO4 / ton of black powder. Water vapor in the dust-containing flue gas during the mixing process is separated and dust is collected. The mixed acid powder is crushed before calcination. After crushing, the particle size of the powder is less than 3cm. The crushed mixed acid powder is stirred for 10 minutes before calcination.

[0108] S3: Mix the mixed acid powder with dust and then calcine it under low temperature and high temperature conditions to obtain calcined material; the low temperature condition is 420℃, and the sulfur dioxide content is 5v%; the high temperature condition is 720℃, and the sulfur dioxide content is 0.3v% and the oxygen content is 0.5v%.

[0109] S4: The calcined material is crushed and leached with water. After pressure filtration, a lithium-containing solution and filter residue are obtained. The particle size of the crushed calcined material is less than 0.5 cm, the lithium leaching rate is 91%, and the contents of Co, Ni and Mn in the lithium-containing solution are 0.08 g / L, 0.04 g / L and 3.4 g / L, respectively.

[0110] S5: After adjusting the pH of the lithium-containing solution to remove impurities such as Co, Ni, and Mn, add sodium carbonate solution and precipitate to obtain lithium carbonate product.

[0111] Example 3

[0112] S1: Mix the battery black powders of different compositions in a specific ratio. After mixing, the C content in the battery black powder is 12.5wt% and the Li content is 6.4wt%.

[0113] S2: The battery black powder with the above proportions is mixed with concentrated sulfuric acid in a certain ratio to obtain mixed acid powder. The concentration of concentrated sulfuric acid is 87wt%, and the amount added is 1.2 tons of H2SO4 / ton of black powder. Water vapor in the dust-containing flue gas during the mixing process is separated and dust is collected. The mixed acid powder is crushed before calcination. After crushing, the particle size of the powder is less than 3cm. The crushed mixed acid powder is stirred for 50 minutes before calcination.

[0114] S3: Mix the mixed acid powder with dust and then calcine it under low temperature and high temperature conditions to obtain calcined material; the low temperature condition is 620℃, and the sulfur dioxide content is 10v%; the high temperature condition is 750℃, and the sulfur dioxide content is 1v% and the oxygen content is 0.3v%.

[0115] S4: The calcined material is crushed and leached with water. After pressure filtration, a lithium-containing solution and filter residue are obtained. The particle size of the crushed calcined material is less than 0.5 cm, the lithium leaching rate is 97%, and the contents of Co, Ni and Mn in the lithium-containing solution are 1.2 g / L, 0.7 g / L and 4.1 g / L, respectively.

[0116] S5: After adjusting the pH of the lithium-containing solution to remove impurities such as Co, Ni, and Mn, add sodium carbonate solution and precipitate to obtain lithium carbonate product.

[0117] Example 4

[0118] S1: Mix battery black powder of different components in a certain proportion. After mixing, the C content in the battery black powder is 11.2wt% and the Li content is 5.4wt%.

[0119] S2: The battery black powder with the above proportions is mixed with concentrated sulfuric acid in a certain ratio to obtain mixed acid powder. The concentration of concentrated sulfuric acid is 75wt%, and the amount added is 0.8 tons of H2SO4 / ton of black powder. Water vapor in the dust-containing flue gas during the mixing process is separated and dust is collected. The mixed acid powder is crushed before calcination. After crushing, the particle size of the powder is less than 3cm. The crushed mixed acid powder is stirred for 30 minutes before calcination.

[0120] S3: Mix the mixed acid powder with dust and then calcine it under low temperature and high temperature conditions to obtain calcined material; the low temperature condition is 520℃, and the sulfur dioxide content is 0.7v%; the high temperature condition is 840℃, and the sulfur dioxide content is 3v% and the oxygen content is 0.05v%.

[0121] S4: The calcined material is crushed and leached with water. After pressure filtration, a lithium-containing solution and filter residue are obtained. The particle size of the crushed calcined material is less than 0.5 cm, the lithium leaching rate is 94%, and the contents of Co, Ni and Mn in the lithium-containing solution are 0.21 g / L, 0.40 g / L and 5.2 g / L, respectively.

[0122] S5: After adjusting the pH of the lithium-containing solution to remove impurities such as Co, Ni, and Mn, add sodium carbonate solution and precipitate to obtain lithium carbonate product.

[0123] Example 5

[0124] S1: Mix battery black powder of different components in a certain proportion. After mixing, the C content in the battery black powder is 15wt% and the Li content is 4.6wt%.

[0125] S2: The battery black powder with the above proportions is mixed with concentrated sulfuric acid in a certain ratio to obtain mixed acid powder. The concentration of concentrated sulfuric acid is 93wt%, and the amount added is 0.7 tons of H2SO4 / ton of black powder. Water vapor in the dust-containing flue gas during the mixing process is separated and dust is collected. The mixed acid powder is crushed before calcination. After crushing, the particle size of the powder is less than 3cm. The crushed mixed acid powder is stirred for 15 minutes before calcination.

[0126] S3: Mix the mixed acid powder with dust and then calcine it under low temperature and high temperature conditions to obtain calcined material; the low temperature condition is 240℃, and the sulfur dioxide content is 0.9v%; the high temperature condition is 770℃, and the sulfur dioxide content is 3v% and the oxygen content is 0.2v%.

[0127] S4: The calcined material is crushed and leached with water. After pressure filtration, a lithium-containing solution and filter residue are obtained. The particle size of the crushed calcined material is less than 0.5 cm, the lithium leaching rate is 95%, and the contents of Co, Ni and Mn in the lithium-containing solution are 0.7 g / L, 0.3 g / L and 4.8 g / L, respectively.

[0128] S5: After adjusting the pH of the lithium-containing solution to remove impurities such as Co, Ni, and Mn, add sodium carbonate solution and precipitate to obtain lithium carbonate product.

[0129] Comparative Example 1

[0130] S1: The battery black powder (i.e. waste lithium battery cathode material) is decarbonized to reduce its carbon content to below 1 wt% (the C content in the black powder after decarbonization is 0.6 wt%) and the Li content is 3.9 wt%.

[0131] S2: The above-mentioned battery black powder is mixed with concentrated sulfuric acid in a certain proportion to obtain mixed acid powder. The concentration of concentrated sulfuric acid is 87wt%, and the amount added is 0.48 tons of H2SO4 / ton of black powder. Water vapor in the dust-containing flue gas during the mixing process is separated and dust is collected. The mixed acid powder is crushed before calcination. After crushing, the particle size of the powder is less than 3cm. The crushed mixed acid powder is stirred for 20 minutes before calcination.

[0132] S3: Mix the mixed acid powder with dust and then calcine it under low temperature and high temperature conditions to obtain calcined material; wherein the low temperature condition is 240℃ and the sulfur dioxide content is 0.1v%; the high temperature condition is 650℃ and the sulfur dioxide content is 2v% and the oxygen content is 3v%.

[0133] S4: The calcined material is crushed and leached with water. After pressure filtration, lithium-containing solution and filter residue are obtained. The particle size of the crushed calcined material is less than 0.5 cm, the lithium leaching rate is 92%, and the contents of Co, Ni and Mn in the lithium-containing solution are 6.2 g / L, 2.3 g / L and 17.7 g / L, respectively.

[0134] S5: After adjusting the pH of the lithium-containing solution to remove impurities such as Co, Ni, and Mn, add sodium carbonate solution and precipitate to obtain lithium carbonate product.

[0135] Comparative Example 2

[0136] S1: Mix battery black powder (i.e. waste lithium battery cathode material) of different compositions in a certain proportion. After mixing, the C content in the battery black powder is 5.7wt% and the Li content is 3.8wt%.

[0137] S2: The battery black powder with the above proportions is mixed with concentrated sulfuric acid in a certain ratio to obtain mixed acid powder. The concentration of concentrated sulfuric acid is 30wt%, and the amount added is 1.39 tons of H2SO4 / ton of black powder. Water vapor in the dust-containing flue gas during the mixing process is separated and dust is collected. The mixed acid material has a high moisture content and needs to be dried at 100℃ to form mixed acid blocks. Before roasting, the blocks are crushed to a particle size of less than 3cm. The crushed mixed acid powder is stirred for 20 minutes before roasting.

[0138] S3: Mix the mixed acid powder with dust and then calcine it under low temperature and high temperature conditions to obtain calcined material; wherein the low temperature condition is 240℃ and the sulfur dioxide content is 0.4v%; the high temperature condition is 650℃ and the sulfur dioxide content is 3v% and the oxygen content is 1v%.

[0139] S4: The calcined material is crushed and leached with water. After pressure filtration, lithium-containing solution and filter residue are obtained respectively. The particle size of the crushed calcined material is less than 0.5 cm, the lithium leaching rate is 76%, and the contents of Co, Ni and Mn in the lithium-containing solution are 0.31 g / L, 0.14 g / L and 3.5 g / L, respectively.

[0140] S5: After adjusting the pH of the lithium-containing solution to remove impurities such as Co, Ni, and Mn, add sodium carbonate solution and precipitate to obtain lithium carbonate product.

[0141] Comparative Example 3

[0142] S1: Mix battery black powder (i.e. waste lithium battery cathode material) of different compositions in a certain proportion. After mixing, the C content in the battery black powder is 5.7wt% and the Li content is 3.8wt%.

[0143] S2: The battery black powder with the above proportions is mixed with concentrated sulfuric acid in a certain ratio to obtain mixed acid powder. The concentration of concentrated sulfuric acid is 87wt%, and the amount added is 0.48 tons of H2SO4 / ton of black powder. Water vapor in the dust-containing flue gas during the mixing process is separated and dust is collected. The mixed acid powder is crushed before calcination. After crushing, the particle size of the powder is less than 3cm. The crushed mixed acid powder is stirred for 20 minutes before calcination.

[0144] S3: Mix the mixed acid powder with dust and then calcine it under low temperature and high temperature conditions to obtain calcined material; wherein the low temperature condition is 240℃ and the sulfur dioxide content is 0.3v%; the high temperature condition is the same as the low temperature condition, 240℃, the sulfur dioxide content is 0.4v% and the oxygen content is 2v%.

[0145] S4: The calcined material is crushed and leached with water. After pressure filtration, lithium-containing solution and filter residue are obtained respectively. The particle size of the crushed calcined material is less than 0.5 cm, the lithium leaching rate is 49%, and the contents of Co, Ni and Mn in the lithium-containing solution are 31 g / L, 13 g / L and 17 g / L, respectively.

[0146] S5: After adjusting the pH of the lithium-containing solution to remove impurities such as Co, Ni, and Mn, add sodium carbonate solution and precipitate to obtain lithium carbonate product.

[0147] As can be seen from Examples 1 to 5 above, the lithium yield can reach 90%-99%, while the leaching amounts of Co, Ni, Mn, etc., are relatively low. Furthermore, comparing with the comparative examples, it can be seen that compared with Example 1, Comparative Example 1 reduced the carbon content in the battery black powder, resulting in a rapid increase in the Co, Ni, and Mn content in the leachate. This indicates that the reduction in carbon content affected the decomposition rate of sulfates in the high-temperature roasting section. Compared with Example 1, in Comparative Example 2, the total amount of sulfuric acid remained unchanged, but the sulfuric acid concentration was reduced, resulting in a significant decrease in the lithium leaching rate. This was mainly due to the dilution of sulfuric acid, leading to insufficient sulfation reaction in the material and uneven distribution of sulfuric acid after evaporation. Compared with Example 1, in Comparative Example 3, setting the original high-temperature section temperature to be the same as the low-temperature section greatly reduced the lithium leaching rate, while the leaching rates of Co, Ni, and Mn were very high, failing to achieve the purpose of selective leaching.

[0148] This application embodiment utilizes a spontaneous exothermic reaction between concentrated sulfuric acid and battery black powder to induce sulfation of the metals in the black powder without an external heat source. Through two gradients of roasting—low-temperature sulfur migration and high-temperature sulfur release—it achieves the conversion of lithium in different chemical states to lithium sulfate, and the conversion of cobalt, nickel, and manganese in different chemical states to oxides, thereby realizing highly efficient and selective lithium leaching. This application embodiment features a short process flow, low cost, modularity, easy scalability, and wide applicability of raw materials, and can be industrialized using standard equipment. The lithium recovery rate of this application embodiment can reach 90%-99%, and the lithium leaching rate can be more than 25 times that of cobalt and nickel. Compared with existing technologies, the lithium recovery method provided by this application embodiment has high lithium recovery and selectivity; requires no other auxiliary materials besides sulfuric acid, has low cost, and is easy to industrialize.

[0149] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method of recovering lithium, characterized by, The application relates to a method for recycling lithium. The method comprises the following steps: Providing waste lithium battery positive electrode material; Mixing and treating the waste lithium battery positive electrode material with concentrated sulfuric acid and partially reacting to obtain mixed acid material; Roasting the mixed acid material at a first temperature and a second temperature in sequence to obtain roasted material, wherein the second temperature is greater than the first temperature; performing leaching treatment on the roasted material with water, performing filtration treatment to obtain a lithium-containing solution; and performing purification treatment on the lithium-containing solution to obtain recycled lithium material; The waste lithium battery positive electrode material is prepared so that the carbon content in the waste lithium battery positive electrode material is 5wt%-30wt%, and the lithium content is 0.5wt%-6.5wt%; The first temperature is 150 DEG C-680 DEG C, and the roasting treatment is performed at the first temperature until the content of sulfur dioxide in the roasting atmosphere is greater than 0.05v%; 2. The method of recovering lithium according to claim 1, wherein The second temperature is 650 DEG C-850 DEG C, and the roasting treatment is performed at the second temperature until the content of sulfur dioxide in the roasting atmosphere is less than 10v%, and the content of oxygen is less than 15v%.

3. The method of recovering lithium according to claim 1, wherein The concentration of the concentrated sulfuric acid is 70wt%-100wt%, and / or the mass ratio of the concentrated sulfuric acid to the waste lithium battery positive electrode material in the mixed acid material is 0.3-1.

5.

4. The method of recovering lithium according to claim 1, wherein Before the roasting treatment of the mixed acid material, the mixed acid material is further subjected to crushing treatment so that the particle size of the material in the mixed acid material is less than 3cm; and / or the mixed acid material is further subjected to stirring treatment for a first time length before the roasting treatment.

5. The method of recovering lithium according to claim 1, wherein Before the leaching treatment of the roasted material with water, the roasted material is further subjected to crushing treatment so that the particle size of the material in the roasted material is less than 0.5cm.

6. A recycled lithium material, characterized in that, The recycled lithium material comprises lithium carbonate, and the purification treatment of the lithium-containing solution comprises adding a carbonate solution into the lithium-containing solution to precipitate and separate the lithium carbonate; or the recycled lithium material comprises lithium phosphate, and the purification treatment of the lithium-containing solution comprises adding a phosphate solution into the lithium-containing solution to precipitate and separate the lithium phosphate. The recycled lithium is prepared by the method according to any one of claims 1-5.

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