Method for efficiently and preferentially separating and recovering lithium from waste lithium batteries

Abstract

The application discloses a method for efficiently and preferentially separating and recovering lithium from waste lithium batteries. The method comprises the following steps: taking waste lithium battery positive black powder as raw material, adding a lithium removal additive to perform a solvothermal reaction, removing lithium from the positive black powder, and then separating a lithium-containing solution from the obtained reaction mixture; then, the lithium-containing solution is sequentially subjected to impurity removal and concentration treatment to obtain a lithium-rich solution; and finally, lithium ions in the lithium-rich solution are converted into a lithium-containing product. The method can realize deep removal of lithium and selective separation of lithium ions and other metal ions in the leaching process of the positive black powder, and has the advantages of simple process, short lithium recovery process, high yield, and less consumption of acid and alkali.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lithium battery recycling, and particularly relates to a method for efficiently and preferentially separating and recovering lithium from waste lithium batteries. BACKGROUND

[0002] Lithium is a strategic element necessary for new energy pure electric vehicles and is a core element of lithium ion batteries. With the increasing penetration rate of new energy vehicles, the number of power lithium batteries in use also increases exponentially. After 5-8 years of use, power vehicle batteries enter the stage of scrap, and it is estimated that the scrapped power lithium batteries will reach millions of tons by 2030. Since waste lithium batteries contain strategic elements such as lithium, nickel, and cobalt, and also contain organic solvents, fluorides, phosphides, heavy metals, etc., improper disposal has strong environmental hazards. Therefore, how to safely and environmentally handle such a large amount of waste lithium batteries has attracted great attention from government departments and great interest from researchers.

[0003] Waste lithium batteries have considerable extraction value. For example, ternary material batteries contain elements such as lithium, nickel, and cobalt, which have a much higher grade ratio than natural minerals. Extracting resources such as lithium, nickel, and cobalt from waste lithium batteries can not only provide some resource guarantee for new energy development, but also bring good economic benefits to enterprises. In industry, there are two methods for recovering valuable metal elements from waste lithium batteries: pyrometallurgy and hydrometallurgy. Pyrometallurgy mainly uses high-temperature smelting, supplemented by auxiliary reagents such as molten salt and reducing agent, to alloy nickel and cobalt at high temperature, and lithium enters the fly ash or slag, which is then subjected to wet leaching to extract lithium. The recovered nickel-cobalt alloy is then purified by wet method and recycled for industrial production. This method is mainly derived from European and American countries, is simple to operate, has mature equipment, and is easy to scale up, but has the disadvantages of high energy consumption and low lithium recovery rate, and is less used in China. In China, hydrometallurgy is mainly used, supplemented by low-temperature pyrometallurgical stripping of current collectors in the front-end disassembly section. The key to hydrometallurgy is efficient leaching, separation, and purification of elements. The leaching reagent is mainly inorganic acid + hydrogen peroxide, and the separation and purification methods include extraction, electrodeposition, and stepwise precipitation. Common inorganic acids include hydrochloric acid, sulfuric acid, nitric acid, and even phosphoric acid. Many scholars have studied organic acid leaching, such as citric acid and malic acid. Extraction is the main separation and purification method, which has developed from single extractant to multi-element synergistic extraction. The products recovered by hydrometallurgy have high purity and can be used as raw materials for battery production, but also have problems such as high acid consumption, long separation stages, and difficulty in treating concentrated brine.

[0004] Many domestic and foreign patents have been developed for separating and extracting valuable elements from waste lithium batteries, such as CN201711009072.2, CN201711287912.1, CN201610856995.0, CN201710207790.4, CN202010077537.3, etc. Invention patents, using sulfide assisted roasting, carbon thermal reduction roasting, and reducing agent assisted methods, improve leaching efficiency and thus improve the recovery rate of valuable metals. Many scholars have also published selective leaching literature. For example, Zheng Xiaohong et al. studied the ammonia-ammonium sulfate leaching of the nickel-cobalt-manganese ternary system. Under the optimized process, the leaching rates of lithium, nickel, cobalt, and manganese were 95.3%, 89.8%, 80.7%, and 4.3%, respectively, realizing the selective separation of lithium and transition metal elements from copper and aluminum. Li Li of North University of Science and Technology also conducted a leaching process after ammonium chloride roasting, which improved the leaching efficiency of lithium and cobalt. The above invention patents and literature have improved the leaching efficiency of waste lithium batteries and indirectly improved the recovery rate, but have not achieved selective separation of lithium and other metal elements in the leaching process.

[0005] There are many recycling technologies for waste lithium batteries. Early recycling technologies only focused on the purification of some metal elements with the highest economic value, and the methods were relatively single. A representative is the recovery of cobalt from waste lithium cobalt oxide, without comprehensive recovery of lithium. In the recycling process, lithium and other elements are basically dissolved in acid, and then combined with precipitation, electrochemistry, and extraction to separate and extract valuable metal elements. The team has proposed in patents CN201811093703, CN201811093717.X, etc. to separate lithium by using nanofiltration membrane technology and prepare battery-grade lithium carbonate. Although this process overcomes the traditional way of separating and purifying lithium, it also dissolves the positive material and then separates the metal ions by membrane method, which consumes a large amount of inorganic acid. SUMMARY

[0006] The main purpose of the present application is to provide a method for efficiently and preferentially separating and recovering lithium from waste lithium batteries, to overcome the deficiencies in the prior art.

[0007] To achieve the above-mentioned purposes, the technical solutions adopted by the embodiments of the present application include:

[0008] The present application provides a method for efficiently and preferentially separating lithium from waste lithium batteries, comprising: at least allowing the waste lithium battery positive black powder to react with a delithiation aid to remove lithium from the positive black powder, and then separating a lithium-containing solution from the obtained reaction mixture after the end of the solvothermal reaction.

[0009] Further, the method for efficiently and preferentially separating lithium from waste lithium batteries comprises:

[0010] The positive black powder of the waste lithium battery is mixed with a solution of a lithium removal aid to perform the solvothermal reaction, so as to remove lithium from the positive black powder, and the pH value of the solution of the lithium removal aid is 4-5.5.

[0011] After the solvothermal reaction is completed, a lithium-containing solution and a lithium removal residue are separated from the obtained reaction mixture, the total concentration of impurity ions in the lithium-containing solution is less than 1 mg / L, and the impurity ions include at least one of nickel ions, cobalt ions and manganese ions.

[0012] The lithium-containing solution is sequentially subjected to impurity removal and concentration treatment to obtain a lithium-rich solution.

[0013] Further, the method for efficiently and preferentially separating lithium from waste lithium batteries specifically comprises: using a divalent metal ion chelating resin to perform the impurity removal treatment on the lithium-containing solution, then adjusting the pH value of the impurity-removed lithium-containing solution to 10-11, and then performing the concentration treatment on the lithium-containing solution by using a reduced-pressure distillation method, and simultaneously condensing and recovering the volatilized lithium removal aid.

[0014] Further, the method for efficiently and preferentially separating lithium from waste lithium batteries further comprises: reusing the recovered lithium removal aid to perform the solvothermal reaction.

[0015] Further, the method for efficiently and preferentially separating lithium from waste lithium batteries further comprises: converting lithium ions in the lithium-rich solution into a lithium-containing product, and the lithium-containing product includes lithium carbonate or lithium hydroxide.

[0016] The application further provides a method for recovering lithium from waste lithium batteries, comprising:

[0017] The waste lithium batteries are disassembled and crushed, and then sieved to obtain positive black powder of the waste lithium batteries.

[0018] Lithium is separated from the positive black powder by using the method.

[0019] Compared with the prior art, the application has the following beneficial effects:

[0020] (1) The application can preferentially extract lithium, efficiently extract lithium and recover lithium in a short process, specifically, in the leaching process, lithium is deeply removed and separated from transition metal ions, and the selection separation coefficient is greater than 180; the lithium removal efficiency is high, and is greater than 99.2%, the dissolution rate of nickel is less than 1%, the dissolution rate of cobalt is less than 0.5%, and the dissolution rate of manganese is less than 0.5%; due to the foregoing leaching process, a qualified lithium-rich solution can be obtained by simply removing impurities from the lithium-containing solution, and the processes such as extraction and deposition are avoided, so that the lithium recovery process is greatly shortened, and the lithium yield is improved.

[0021] (2) The present application preferentially separates lithium and other divalent metal ions in the leaching process, and a small amount of transition metal ions brought in can be removed by using a chelating resin to meet the impurity control requirements of the lithium-rich solution, greatly shortening the lithium recovery process and improving the lithium yield; at the same time, the separation and purification process greatly reduces the amount of acid and eliminates the use of organic reagents, which is green and low-carbon.

[0022] (3) Through the treatment of the present application, the product purity is high, and the lithium yield is high, that is, the lithium carbonate product of the present application has a purity of more than 99.5%, and the comprehensive recovery rate of lithium ions is more than 96%. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can also be obtained by those skilled in the art without creating laborious work.

[0024] Figure 1 is a flowchart of the method for recovering lithium from waste lithium batteries in an embodiment of the present application.

[0025] Figure 2 is an SEM image of the positive electrode material before delithiation in Example 1 of the present application.

[0026] Figure 3 is an SEM image of the leaching residue after delithiation in Example 1 of the present application. DETAILED DESCRIPTION

[0027] In view of the low recovery efficiency of lithium in existing waste lithium batteries, unreasonable recovery procedures, and large acid consumption, the present inventors have developed a method and system for efficiently and preferentially separating and recovering lithium from waste lithium batteries through long-term research and a large number of practices, which comprises the following process steps: solvent thermal delithiation, filtration, washing, impurity removal, concentration and crystallization of waste lithium battery positive electrode black powder, using the proton exchange action under weak acid conditions to replace the lithium ions inside the positive electrode material crystal while maintaining the overall integrity of the crystal; and in the delithiation process, elemental lithium is transferred from the solid phase to the solvent, while transition metal ions such as nickel, cobalt and manganese exist in the form of solid phase, realizing selective leaching separation of lithium; the lithium-containing solution is subjected to deep impurity removal, concentration and precipitation to obtain lithium carbonate product; the condensed and recovered solvent can be recycled and not discharged; and the solid phase transition metal elements are classified and utilized according to the types and contents of impurities, so as to overcome the shortcomings of the traditional recovery process, such as complicated process steps, large amount of acid and alkali, and high energy consumption, caused by full dissolution of the positive electrode material and then classified recovery by using extraction and electrodeposition technology. The technical solutions, implementation process and principles will be further explained as follows.

[0028] One aspect of the embodiments of the present application provides a method for efficiently and preferentially separating lithium from waste lithium batteries, comprising: at least subjecting waste lithium battery positive electrode black powder to a solvothermal reaction with a lithium removal aid to remove lithium from the positive electrode black powder, and then separating a lithium-containing solution from a reaction mixture obtained after the solvothermal reaction.

[0029] The embodiments of the present application extract lithium from waste lithium battery black powder, which is different from the existing hydrometallurgical process. In the leaching process, lithium enters the solution, and transition metal elements remain in the solid phase, thereby realizing leaching separation, efficient separation of lithium, short process recovery, and significant reduction in acid consumption.

[0030] In some preferred embodiments, the method for efficiently and preferentially separating lithium from waste lithium batteries comprises:

[0031] At least the waste lithium battery positive electrode black powder is uniformly mixed with a solution of the lithium removal aid, and then the solvothermal reaction is performed to remove lithium from the positive electrode black powder, and the pH value of the solution of the lithium removal aid is 4-5.5;

[0032] After the solvothermal reaction, a lithium-containing solution and a lithium removal residue are separated from the reaction mixture obtained, the total concentration of impurity ions in the lithium-containing solution is less than 1 mg / L, and the impurity ions include at least one of nickel, cobalt, and manganese ions;

[0033] The lithium-containing solution is sequentially subjected to impurity removal and concentration treatment to obtain a lithium-rich solution.

[0034] In some preferred embodiments, the conditions of the solvothermal reaction include a reaction temperature of 140-230°C, a reaction time of 6-24h, a liquid-solid mass ratio in the reaction system of 6:1-20:1, and a molar concentration of the lithium removal aid of 2-8mol / L.

[0035] In some preferred embodiments, the method for efficiently and preferentially separating lithium from waste lithium batteries specifically comprises: subjecting the lithium-containing solution to the impurity removal treatment with a divalent metal ion chelating resin, then adjusting the pH value of the impurity-removed lithium-containing solution to 10-11, and then performing the concentration treatment on the lithium-containing solution by using a reduced-pressure distillation method, while condensing and recovering the volatilized lithium removal aid.

[0036] The existing waste battery recycling process is basically full leaching or assisted by other reducing agents to improve leaching efficiency, and then nickel, cobalt, and manganese are recovered by precipitation and extraction, and then lithium is extracted. This process is particularly cumbersome, requires 4-5 stages of acid and alkali consumption, and has a long process, which is not easy to accurately control. The embodiments of the present application preferentially separate lithium and other divalent metal ions in the leaching process, and then remove impurities by resin to obtain lithium products, which is different from the existing full-solution extraction process.

[0037] In some more preferred embodiments, the temperature of the reduced pressure distillation is 50-80℃, and the pressure is reduced to 400-600mmHg.

[0038] In some preferred embodiments, the method for efficiently and preferentially separating lithium from waste lithium batteries further comprises: reusing the recovered lithium-removing auxiliary agent to perform the solvothermal reaction.

[0039] The lithium-removing auxiliary agent provided by the embodiments of the present application can only remove lithium from the positive electrode material under hydrothermal conditions without dissolving other transition metal ions, and the agent can be recycled and is not discharged, which is green and low-carbon.

[0040] In some more preferred embodiments, the recovered lithium-removing auxiliary agent has a recovery concentration of 3-20%.

[0041] In some preferred embodiments, the solvothermal reaction is a hydrothermal reaction.

[0042] In some preferred embodiments, the lithium-removing auxiliary agent can include one or a combination of two or more of ammonium sulfate, ammonium chloride, ammonium acetate, ammonium carbonate, ammonium nitrate, etc., but is not limited thereto.

[0043] In some preferred embodiments, the positive electrode black powder can include one or a combination of two or more of lithium cobalt oxide ternary material, nickel-cobalt-manganese ternary material, lithium manganese oxide ternary material, etc., but is not limited thereto.

[0044] In some more preferred embodiments, the method for efficiently and preferentially separating lithium from waste lithium batteries further comprises: converting lithium ions in the lithium-rich solution into a lithium-containing product, and the lithium-containing product includes lithium carbonate or lithium hydroxide.

[0045] In the embodiments of the present application, the lithium-containing solution has a high lithium content, the total amount of leaching solution to be treated is small, the lithium extraction process is simple, and only a small amount of transition metal ions can be removed by using a chelating resin to meet the impurity control requirements of the lithium-rich solution; under the optimized conditions of the present application, the lithium concentration in the leaching solution reaches more than 10g / L, the transition metal ions in the solution can be reduced by more than 98%, and the lithium recovery process is greatly shortened and the lithium yield is improved; at the same time, the separation and purification process greatly reduces the amount of acid and eliminates the use of organic reagents, which is green and low-carbon.

[0046] Among them, as one of the more specific implementation cases of the present application, see Figure 1As shown, the method for recovering lithium from waste lithium batteries can specifically include the following steps: taking waste lithium battery positive black powder (including lithium cobalt oxide ternary material, nickel cobalt manganese ternary material and lithium manganese oxide ternary material) as raw material, adding a lithium removal aid, and then transferring to a polytetrafluoroethylene tank with a liner for hydrothermal treatment; after lithium removal, washing and filtering to obtain a lithium-containing solution and a black lithium removal residue; then using a divalent metal ion chelating resin to deeply remove impurities from the lithium-containing solution, and then adding an alkaline substance to adjust the pH to 10-11, and then concentrated by vacuum distillation to obtain a lithium-rich solution; finally, saturated carbonic acid solution is added to the lithium-rich solution for lithium precipitation conversion, and then washed and dried to obtain lithium carbonate product, and the volatilized lithium removal aid is recovered by condensation during the concentration process.

[0047] In some preferred embodiments, the alkaline substance can include any one or a combination of two or more of ammonia, sodium hydroxide, potassium hydroxide, sodium oxide, potassium oxide, calcium hydroxide, etc., but is not limited thereto.

[0048] Another aspect of the embodiments of the present application provides a method for recovering lithium from waste lithium batteries, comprising:

[0049] After the waste lithium battery is disassembled and crushed, the waste lithium battery positive black powder is obtained by screening;

[0050] The lithium is separated from the positive black powder by the method described above.

[0051] In summary, the embodiments of the present application overcome the shortcomings of the conventional recovery process, such as complicated process steps, large amount of acid and alkali, and high energy consumption, caused by full dissolution of the positive material and then classified recovery by extraction and electrodeposition, etc. The embodiments of the present application achieve selective separation of lithium and other metal ions during leaching, and have the advantages of simple process, short lithium recovery process, high yield, and less amount of acid and alkali.

[0052] The technical solutions of the present application will be further described in detail below in combination with several preferred embodiments and the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application. The test methods not specified in the following embodiments are usually carried out under conventional conditions.

[0053] Embodiment 1

[0054] The SEM image of a certain mixed waste ternary positive black powder as raw material is as follows: Figure 2As shown, the raw material is composed of spherical secondary particles made of primary particles with smooth surface, and the particle size is about 10 μm. First, 15 g of the positive electrode black powder is weighed, and 90 ml of 5 mol / L ammonium chloride solution is measured by a graduated cylinder. The black powder and the ammonium chloride solution are transferred to a lined hydrothermal tank for delithiation, the delithiation temperature is 200 ℃, and the holding time is 10 h. After the reaction is completed, washing and filtration are performed to obtain a lithium-containing solution and delithiated residue, respectively. The main component of the delithiated residue is a nickel-cobalt-manganese mixed material, and the SEM image thereof is as shown in FIG. 2. Figure 3 As shown, the secondary particles basically maintain the original overall shape, only a small amount of secondary particles are depolymerized into primary particles, and the surface of the primary particles becomes rough and is covered with "pinhole" small holes. Preliminary analysis shows that the delithiation medium etches the crystal at the solid-liquid interface to cause surface roughening. The composition of the lithium-containing solution is shown in Table 1 as follows:

[0055] Table 1 Composition of lithium-containing solution (unit: mg / L)

[0056] Class Aluminium Cobalt Lithium Manganese Nickel Copper Iron Sodium Content 16.65 91.11 10578.89 Not detected 605.28 Not detected Not detected 11.67

[0057] The lithium-containing solution is treated by a chelating resin to adsorb and remove impurity ions such as nickel, cobalt, and aluminum. After detection, when the impurity ions are qualified, 1 mol / L sodium hydroxide solution is used to adjust the pH to about 10, vacuum distillation is performed, the pressure is reduced to 500 mmHg, and the temperature is 70 ℃. Ammonium chloride is recovered by condensation, and the recovered ammonium chloride can be recycled. When the lithium concentration reaches 25 g / L, the concentration is stopped, and lithium precipitation conversion is performed. The conversion temperature is 85 ℃, saturated carbonic acid solution is added to the lithium-rich solution, and the addition amount of the saturated carbonic acid solution is 10% of the lithium-rich solution. After washing and drying, lithium carbonate products are obtained.

[0058] Example 2

[0059] A commercially available mixed waste ternary positive electrode black powder is used as the raw material. First, 10 g of the positive electrode black powder is weighed, and 200 ml of 2 mol / L ammonium chloride solution is measured by a graduated cylinder. The black powder and the ammonium chloride solution are transferred to a lined hydrothermal tank for delithiation, the delithiation temperature is 230 ℃, and the holding time is 6 h. After the reaction is completed, washing and filtration are performed to obtain a lithium-containing solution and delithiated residue, respectively. The main component of the delithiated residue is a nickel-cobalt-manganese mixed material. The composition of the lithium-containing solution is shown in Table 2 as follows:

[0060] Table 2 Composition of lithium-containing solution (unit: mg / L)

[0061] Class Aluminium Cobalt Lithium Manganese Nickel Copper Iron Sodium Content 23.24 75.92 4029.35 10.27 355.16 2.58 Not detected 5.92

[0062] The lithium-containing solution is treated by chelating resin to remove impurity ions such as nickel, cobalt and aluminum by adsorption, and after detection of the impurity ions, the pH is adjusted to about 10 by using 0.5 mol / L sodium hydroxide solution, and vacuum distillation is performed to 400 mmHg at a temperature of 50°C, and ammonium chloride is recovered by condensation, and the recovered ammonium chloride can be recycled. When the lithium concentration reaches 30 g / L, the concentration is stopped, and lithium precipitation conversion is performed at a conversion temperature of 85°C, and saturated carbonic acid solution is added to the lithium-rich solution, and the amount of the saturated carbonic acid solution added is 10% of the lithium-rich solution, and lithium carbonate product is obtained after washing and drying.

[0063] Example 3

[0064] A certain ternary positive electrode black powder is used as raw material. First, 20 g of the positive electrode black powder is weighed, and 100 ml of 2 mol / L ammonium chloride and 100 ml of 3 mol / L ammonium acetate solution are measured by a graduated cylinder. The black powder and the mixed solution are transferred to a water-heating tank with an inner liner to remove lithium, the lithium removal temperature is 140°C, and the holding time is 24 h. After the reaction is completed, washing and filtration are performed, and a lithium-containing solution and a lithium removal residue are obtained. The main component of the lithium removal residue is a nickel-cobalt-manganese mixed material. The composition of the lithium-containing solution is shown in Table 3.

[0065] Table 3 Composition of lithium-containing solution (unit: mg / L)

[0066] Class Aluminium Cobalt Lithium Manganese Nickel Copper Iron Sodium Content 8.45 65.43 8188.24 Not detected 272.56 Not detected Not detected Not detected

[0067] The lithium-containing solution is treated by chelating resin to remove impurity ions such as nickel, cobalt and aluminum by adsorption, and after detection of the impurity ions, the pH is adjusted to about 11 by using 2 mol / L sodium hydroxide solution, and vacuum distillation is performed to 600 mmHg at a temperature of 80°C, and ammonium salt is recovered by condensation, and the recovered ammonium salt can be recycled. When the lithium concentration reaches 20 g / L, the concentration is stopped, and lithium precipitation conversion is performed at a conversion temperature of 85°C, and saturated carbonic acid solution is added to the lithium-rich solution, and the amount of the saturated carbonic acid solution added is 10% of the lithium-rich solution, and lithium carbonate product is obtained after washing and drying.

[0068] Example 4

[0069] A mixed ternary positive electrode black powder obtained by disassembly is used as raw material. First, 15 g of the positive electrode black powder is weighed, and 50 ml of 2 mol / L ammonium chloride solution and 70 ml of 5 mol / L ammonium sulfate are measured by a graduated cylinder to form a mixed lithium removal agent. The black powder and the mixed solution are transferred to a water-heating tank with an inner liner to remove lithium, the lithium removal temperature is 160°C, and the holding time is 24 h. After the reaction is completed, washing and filtration are performed, and a lithium-containing solution and a lithium removal residue are obtained. The main component of the lithium removal residue is a nickel-cobalt-manganese mixed material. The composition of the lithium-containing solution is shown in Table 4.

[0070] Table 4 Composition of lithium-containing solution (unit: mg / L)

[0071] Class Aluminium Cobalt Lithium Manganese Nickel Copper Iron Sodium Content 42.65 105.28 9255.68 Not detected 582.70 12.93 Not detected Not detected

[0072] The lithium-containing solution is treated by chelating resin to remove impurity ions such as nickel, cobalt and aluminum by adsorption, and after detection of the impurity ions, the pH is adjusted to about 11 by using 4 mol / L sodium hydroxide solution. The lithium-containing solution is reduced in pressure to 450 mmHg at a temperature of 65°C by vacuum distillation, and the ammonium salt is recovered by condensation. The recovered ammonium salt can be recycled. When the lithium concentration reaches 20 g / L, the concentration is stopped, and lithium precipitation conversion is performed at a conversion temperature of 85°C. Saturated carbonic acid solution is added to the lithium-rich solution, and the amount of the saturated carbonic acid solution added is 10% of the lithium-rich solution. After washing and drying, lithium carbonate product is obtained.

[0073] Example 5

[0074] The mixed ternary positive electrode black powder obtained by disassembly is used as the raw material. First, 15 g of the positive electrode black powder is weighed, and 115 ml of 8 mol / L ammonium chloride solution and 5 ml of 1 mol / L ammonium nitrate are used to prepare a mixed lithium removal agent. The black powder and the mixed solution are transferred to a hydrothermal tank with a liner for lithium removal. The lithium removal temperature is 180°C, and the holding time is 12 h. After the reaction is completed, washing and filtration are performed to obtain a lithium-containing solution and a lithium removal residue. The main component of the lithium removal residue is a nickel-cobalt-manganese mixed material. The composition of the lithium-containing solution is shown in Table 5.

[0075] Table 5 Composition of lithium-containing solution (unit: mg / L)

[0076] Class Aluminium Cobalt Lithium Manganese Nickel Copper Iron Sodium Content 53.29 156.13 9332.72 15.73 623.95 12.93 Not detected Not detected

[0077] The lithium-containing solution is treated by chelating resin to remove impurity ions such as nickel, cobalt and aluminum by adsorption, and after detection of the impurity ions, the pH is adjusted to about 11 by using 4 mol / L sodium hydroxide solution. The lithium-containing solution is reduced in pressure to 450 mmHg at a temperature of 65°C by vacuum distillation, and the ammonium salt is recovered by condensation. The recovered ammonium salt can be recycled. When the lithium concentration reaches 20 g / L, the concentration is stopped, and lithium precipitation conversion is performed at a conversion temperature of 85°C. Saturated carbonic acid solution is added to the lithium-rich solution, and the amount of the saturated carbonic acid solution added is 10% of the lithium-rich solution. After washing and drying, lithium carbonate product is obtained.

[0078] In addition, the present inventors have also conducted tests on other raw materials, process operations and process conditions described in the present specification with reference to the foregoing examples, and ideal results have been obtained.

[0079] While the application has been described with reference to the illustrative embodiments, those skilled in the art will understand that various other changes, omissions, and / or additions can be made without departing from the spirit and scope of the application. Further, many modifications can be made to adapt a particular situation or material to the teachings of the application without departing from its scope. Therefore, it is intended that the application not be limited to the disclosed embodiments, but will include all embodiments falling within the scope of the appended claims. Moreover, unless specifically stated otherwise, any use of the terms first, second, etc., does not denote any ordinal, or importance, but merely distinguishes one element from another.

Claims

1. A method for efficiently and preferentially separating lithium from spent lithium batteries, characterized in that, include: The waste lithium battery cathode black powder is uniformly mixed with a solution of delithiation aid and then subjected to a hydrothermal reaction to remove lithium from the cathode black powder. The pH value of the delithiation aid solution is 4-5.

5. The hydrothermal reaction conditions include: a reaction temperature of 140-180℃, a time of 6-24h, a liquid-to-solid mass ratio of 6:1-20:1 in the reaction system, and a molar concentration of 2-8 mol / L for the delithiation aid. The delithiation aid is selected from one or more of ammonium sulfate, ammonium chloride, ammonium acetate, ammonium carbonate, or ammonium nitrate. After the hydrothermal reaction is completed, a lithium-containing solution and a delithiation residue are separated from the obtained reaction mixture. The total concentration of impurity ions in the lithium-containing solution is less than 1 mg / L, and the impurity ions include at least one of nickel, cobalt, and manganese ions. The lithium-containing solution is purified by using a divalent metal ion chelating resin. The pH value of the purified lithium-containing solution is then adjusted to 10-11. The lithium-containing solution is then concentrated by vacuum distillation to obtain a lithium-rich solution. At the same time, the volatilized delithiation aid is condensed and recovered and reused in the hydrothermal reaction. The vacuum distillation temperature is 50-80℃ and the pressure is reduced to 400-600 mmHg.

2. The method for efficiently and preferentially separating lithium from spent lithium batteries according to claim 1, characterized in that: The recovered lithium removal aid has a recovery concentration of 3-20%.

3. The method for efficiently and preferentially separating lithium from spent lithium batteries according to claim 1, characterized in that: The cathode black powder includes one or more of the following: lithium cobalt oxide material, nickel-cobalt-manganese ternary material, and lithium manganese oxide material.

4. The method for efficiently and preferentially separating lithium from spent lithium batteries according to claim 1, characterized in that, Also includes: The lithium ions in the lithium-rich solution are converted into lithium-containing products, including lithium carbonate or lithium hydroxide.

5. A method for recovering lithium from spent lithium batteries, characterized in that, include: After dismantling and crushing waste lithium batteries, the positive electrode black powder of waste lithium batteries is obtained by screening. Lithium is separated from the cathode black powder using the method described in any one of claims 1-4.

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