Method for recovering aluminum and lithium elements by sintering method

Abstract

The present invention provides a method for recovering aluminum and lithium elements by sintering. The method comprises the following steps: a crushing and slurrying step: crushing the positive electrode of a waste lithium battery to obtain a crushed material; preparing a slurry comprising the crushed material, an ammonium salt, and a carbonate; a sintering step: sintering the slurry at a temperature of 500-800°C to obtain a sintered material and a sintering tail gas; a leaching step: leaching the sintered material with a dilute alkaline solution to obtain an eluate; a lithium precipitation step: adding a lithium precipitation agent to the eluate to carry out a lithium precipitation reaction to obtain a lithium precipitate and a post-lithium precipitation liquid; and a seeding step: passing the post-lithium precipitation liquid into the post-lithium precipitation liquid, followed by evaporation and concentration, and then adding seed crystals to the concentrated liquid and stirring to induce the precipitation of aluminum precipitates. The present invention effectively solves the problem in the prior art of the inability to effectively separate aluminum and electrode powder from waste lithium batteries, which adversely affects subsequent acid leaching or alkaline dissolution processes.

Description

Technical Field

[0001] The present invention relates to the technical field of waste battery resource recycling, and in particular to a method for recycling aluminum and lithium elements by a sintering process. Background Art

[0002] With the widespread promotion and application of new energy vehicles, my country has firmly established itself as the world's leading producer and seller of new energy vehicles. This has led to the widespread retirement of power batteries. In 2020, the earliest batch of power batteries will be retired. These scrapped power batteries represent valuable "urban mines," and the efficient recycling and reuse of their valuable metals can improve resource efficiency. The question of how to comprehensively utilize these batteries is particularly pressing and crucial for reducing my country's external dependence, safeguarding national resource strategic security, and developing a circular economy.

[0003] Currently, the recycling strategy for used lithium batteries generally relies on a combination of dry and traditional hydrometallurgical recycling. Specifically, the used lithium batteries are crushed and screened to obtain positive and negative electrode powders, aluminum granules, copper granules, and broken separators. The positive and negative electrode powders are then subjected to acid leaching, impurity removal, extraction, and chemical precipitation to recover the elemental salts. However, the crushed aluminum granules often carry electrode powders, resulting in lower purity. The positive and negative electrode powders also carry a small amount of fine aluminum particles. Conventional methods for processing the crushed aluminum granules include roasting to burn off the binder, using liquid caustic soda to dissolve the aluminum, and using flotation shakers for mechanochemical separation. The electrode powders are then fed into a wet system through acid leaching and other processes to recover valuable metals such as nickel, cobalt, and manganese.

[0004] However, aluminum powder mixed with the cathode powder enters the wet process, increasing acid consumption in the leaching process and alkali consumption in the impurity removal process. Therefore, how to efficiently, quickly, and environmentally friendly separate aluminum from the cathode powder and improve the recovery rate of valuable elements in spent lithium batteries remains a pressing challenge in the field of resource recovery. Summary of the Invention

[0005] The main purpose of the present invention is to provide a method for recovering aluminum and lithium elements by sintering, so as to solve the problem in the prior art that aluminum and pole powder of waste lithium batteries cannot be effectively separated, which has an adverse effect on subsequent acid leaching or alkaline dissolution processes.

[0006] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, a method for recovering aluminum and lithium elements by a sintering method is provided, which comprises the following steps: a crushing and slurrying step: crushing the positive electrode of a waste lithium battery to obtain a crushed material; preparing a slurry comprising the crushed material, an ammonium salt and a carbonate; a sintering step: sintering the slurry at a temperature of 500 to 800°C to obtain a sintered material and a sintering tail gas; a leaching step: leaching the sintered material with a dilute alkaline solution to obtain an eluate; a lithium precipitation step: adding a lithium precipitation agent to the eluate to carry out a lithium precipitation reaction to obtain a lithium precipitate and a post-lithium precipitation liquid; a seeding step: passing the post-lithium precipitation gas into the post-lithium precipitation liquid, followed by evaporation and concentration, and then adding seed crystals to the concentrated liquid, and stirring to induce the precipitation of aluminum precipitates.

[0007] Furthermore, in the crushing and slurrying step, the ammonium salt is selected from one or more of ammonium chloride, ammonium sulfate, and ammonium nitrate; preferably, the carbonate is selected from one or more of sodium carbonate, sodium bicarbonate, potassium carbonate, and calcium carbonate.

[0008] Furthermore, in the crushing and slurrying step, the weight ratio of the crushed material, ammonium salt and carbonate is 1:(0.1-0.5):(0.1-0.2); preferably, the liquid-solid ratio in the slurry is 1:(2-5).

[0009] Furthermore, the particle size of the crushed material is 50 to 150 meshes.

[0010] Furthermore, the sintering step includes: placing the slurry into a converter, sintering at a temperature of 500-800° C. for 2-6 hours, and collecting sintering exhaust gas; after sintering is completed, cooling to obtain a sintered material.

[0011] Furthermore, in the leaching step, the dilute alkali solution is selected from one or more aqueous solutions of sodium hydroxide, sodium carbonate, sodium bicarbonate, potassium hydroxide, and potassium carbonate; preferably, the weight concentration of the dilute alkali solution is 5 to 10 g / L.

[0012] Furthermore, in the leaching step, the liquid-solid ratio of the dilute alkali solution to the sintering material is (3-6):1; preferably, the leaching temperature in the leaching step is 80-95° C., and the leaching time is 1-5 hours.

[0013] Furthermore, in the lithium precipitation step, the lithium precipitation agent is selected from one or more of sodium carbonate, sodium phosphate, and sodium fluoride; preferably, the amount of the lithium precipitation agent added is 1.2 to 1.5 times the theoretical amount of Li element required in the eluate; preferably, the temperature of the lithium precipitation reaction is 85 to 95° C., and the time is 1 to 4 hours.

[0014] Furthermore, the seeding step includes: passing the sintering tail gas into the lithium precipitation liquid and maintaining it for 0.5 to 2 hours; evaporating and concentrating the lithium precipitation liquid after the reaction at 90 to 100° C. to obtain a concentrated solution; adding aluminum hydroxide with a seed ratio of 0.05 to 0.2 as a seed to the concentrated solution, and inducing the precipitation of aluminum precipitation under stirring at 50 to 70° C.

[0015] Furthermore, in the seeding step, after inducing the precipitation of aluminum, the step of returning the remaining seeding mother liquor as part of the dilute alkaline solution for leaching the sintering material is also included.

[0016] The method for recovering aluminum and lithium elements by a sintering method provided by the present invention comprises the following steps: a crushing and slurrying step: crushing the positive electrode of a waste lithium battery to obtain a crushed material; preparing a slurry comprising the crushed material, an ammonium salt and a carbonate; a sintering step: sintering the slurry at a temperature of 500-800°C to obtain a sintered material and a sintering tail gas; a leaching step: leaching the sintered material with a dilute alkaline solution to obtain an eluate; a lithium precipitation step: adding a lithium precipitation agent to the eluate to carry out a lithium precipitation reaction to obtain a lithium precipitate and a post-lithium precipitation liquid; and a seeding step: passing the post-lithium precipitation liquid into the post-lithium precipitation liquid to carry out a reaction, followed by evaporation and concentration, and then adding seed crystals to the concentrated liquid, stirring and inducing the precipitation of aluminum precipitates.

[0017] In the above-mentioned method provided by the present invention, after the positive electrode of the waste lithium battery is crushed, it is slurried with ammonium salt and carbonate, and then sintered. By means of this slurrying and sintering, the aluminum in the crushed material can be converted into metaaluminate, and the lithium can be converted into soluble lithium salt, and the pole powder material in the sintering process will not change due to its inherent oxide alloy composition. Subsequently, the metaaluminate and soluble lithium salt in the sintered material can be more fully dissolved in the dilute alkaline solution, and then fully separated from the pole powder. After leaching, the lithium precipitate and the aluminum precipitate can be recovered separately through the lithium precipitation step and the seed separation step. Unlike the traditional aluminum recovery method of waste lithium batteries, the present invention combines pyrometallurgical and hydrometallurgical processes to recycle the positive electrode of waste lithium batteries. Lithium and aluminum in the positive electrode of waste lithium batteries can be directly separated and extracted through sintering-leaching, avoiding the acid and alkali consumption in the conventional leaching-dealuminization process, and effectively reducing the loss of aluminum and lithium elements. The crude lithium precipitate and aluminum precipitate obtained through sintering, leaching, lithium precipitation and seed separation have low impurity content and can be directly used for processing in their respective next steps.

[0018] In summary, the present invention effectively solves the problem in the prior art that aluminum and pole powder of waste lithium batteries cannot be effectively separated, which has an adverse effect on the subsequent acid leaching or alkaline dissolution process. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0020] Figure 1 A schematic flow chart of a method for recovering aluminum and lithium elements by a sintering method according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0021] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0022] In order to more effectively separate aluminum, lithium and pole powder from waste lithium batteries, the present invention provides a method for recovering aluminum and lithium elements by sintering. Figure 1 As shown, the method includes the following steps: a crushing and slurrying step: crushing the positive electrode of the waste lithium battery to obtain a crushed material; preparing a slurry including the crushed material, ammonium salt and carbonate; a sintering step: sintering the slurry at a temperature of 500-800°C to obtain a sintered material and a sintering tail gas; a leaching step: leaching the sintered material with a dilute alkaline solution to obtain an eluate; a lithium precipitation step: adding a lithium precipitation agent to the eluate to carry out a lithium precipitation reaction to obtain a lithium precipitate and a lithium precipitation liquid; a seed separation step (crystal seed separation step): passing the sintering tail gas into the lithium precipitation liquid, then evaporating and concentrating it, and then adding seed crystals to the concentrated liquid, stirring to induce the precipitation of aluminum precipitates.

[0023] In the above-mentioned method provided by the present invention, after the positive electrode of the waste lithium battery is crushed, it is slurried with ammonium salt and carbonate, and then sintered. By means of this slurrying and sintering, the aluminum in the crushed material can be converted into metaaluminate, and the lithium can be converted into soluble lithium salt, and the pole powder material in the sintering process will not change due to its inherent oxide alloy composition. Subsequently, the metaaluminate and soluble lithium salt in the sintered material can be more fully dissolved in the dilute alkaline solution, and then fully separated from the pole powder. After leaching, the lithium precipitate and the aluminum precipitate can be recovered separately through the lithium precipitation step and the seed separation step. Unlike the traditional aluminum recovery method of waste lithium batteries, the present invention combines pyrometallurgical and hydrometallurgical processes to recycle the positive electrode of waste lithium batteries. Lithium and aluminum in the positive electrode of waste lithium batteries can be directly separated and extracted through sintering-leaching, avoiding the acid and alkali consumption in the conventional leaching-dealuminization process, and effectively reducing the loss of aluminum and lithium elements. The crude lithium precipitate and aluminum precipitate obtained through sintering, leaching, lithium precipitation and seed separation have low impurity content and can be directly used for processing in their respective next steps.

[0024] In summary, the present invention effectively solves the problem in the prior art that aluminum and pole powder of waste lithium batteries cannot be effectively separated, which has an adverse effect on the subsequent acid leaching or alkaline dissolution process.

[0025] To further improve the sintering effect and allow lithium and aluminum to undergo a more complete sintering reaction to convert into soluble salts, in a preferred embodiment, during the pulverization and slurrying step, the ammonium salt is selected from one or more of ammonium chloride, ammonium sulfate, and ammonium nitrate; and the carbonate is preferably selected from one or more of sodium carbonate, sodium bicarbonate, potassium carbonate, and calcium carbonate. Using these ammonium salts and carbonates allows the temperatures of lithium and aluminum to be more compatible during the sintering process, allowing for a more complete reaction at temperatures between 500 and 800°C, while preventing the powdered material from reacting, thereby better separating the lithium aluminum from the powdered material. More preferably, the ammonium salt is selected from ammonium chloride and / or ammonium sulfate, and the carbonate is selected from sodium carbonate and / or sodium bicarbonate.

[0026] To promote a more complete reaction and reduce resource waste, in a preferred embodiment, during the pulverization and slurrying step, the weight ratio of the pulverized material, ammonium salt, and carbonate is 1:(0.1-0.5):(0.1-0.2); more preferably, the liquid-to-solid ratio in the slurry is 1:(2-5). To improve reaction efficiency, the particle size of the pulverized material is preferably 50 to 150 mesh. In actual operation, the waste lithium battery positive electrode is pulverized using a pulverizer.

[0027] In a preferred embodiment, the sintering step includes: placing the slurry in a converter, sintering at a temperature of 500-800°C for 2-6 hours, and collecting the sintering tail gas; after the sintering is completed, cooling to obtain a sintered material. By controlling the reaction conditions within the above range, the sintering reaction is more complete, the reaction of lithium and aluminum is more complete, and it can be separated from the pole powder more effectively. In addition, tail gas will be generated during the sintering step, and its main components are carbon dioxide and ammonia. By passing it into the post-lithium precipitation liquid, its alkalinity can be adjusted to a more suitable range, and the temperature of the post-lithium precipitation liquid can be adjusted, so that after concentration and the addition of seed crystals, aluminum can be fully precipitated, while also achieving full resource utilization and less pollution.

[0028] To more fully leach soluble lithium and aluminum salts, in a preferred embodiment, the dilute alkali solution in the leaching step is selected from aqueous solutions of one or more of sodium hydroxide, sodium carbonate, sodium bicarbonate, potassium hydroxide, and potassium carbonate; preferably, the weight concentration of the dilute alkali solution is 5-10 g / L. More preferably, the liquid-to-solid ratio of the dilute alkali solution to the sintering material in the leaching step is 3-6:1; preferably, the leaching temperature in the leaching step is 80-95°C, and the leaching time is 1-5 hours. In actual operation, after leaching, the leaching solution and slag are filtered to obtain the slag, which is then sent to an acid leaching purification system for valuable element recovery.

[0029] In the above-mentioned lithium precipitation step, the addition of a lithium precipitation agent can further promote the precipitation of lithium ions and separation from aluminum. In a preferred embodiment, in the above-mentioned lithium precipitation step, the lithium precipitation agent is selected from one or more of sodium carbonate, sodium phosphate, and sodium fluoride; preferably, the amount of lithium precipitation agent added is 1.2 to 1.5 times the theoretical amount of Li element required in the dissolution solution; preferably, the temperature of the lithium precipitation reaction is 85 to 95°C and the time is 1 to 4 hours. Under the above reagents and conditions, lithium ions can be more fully precipitated, and the formed lithium carbonate or lithium fluoride has high purity and less impurities, and can be directly used in the subsequent process.

[0030] In a preferred embodiment, the seeding step includes: passing the calcination tail gas into the post-lithium precipitation solution for 0.5 to 2 hours; evaporating and concentrating the post-lithium precipitation solution at 90 to 100°C to obtain a concentrated solution; adding aluminum hydroxide with a seed ratio of 0.05 to 0.2 as a seed crystal to the concentrated solution, and inducing the precipitation of aluminum ions under stirring at 50 to 70°C. Under the above conditions, aluminum ions can be precipitated in the form of aluminum hydroxide precipitate, and the aluminum hydroxide has high purity and low impurities. The above seed ratio refers to the weight ratio between the added seed aluminum hydroxide and the precipitated aluminum precipitate.

[0031] In short, the present invention aims to solve the technical problems existing in the prior art. To this end, the present invention proposes a method for recovering aluminum and lithium elements by sintering, that is, first crushing and sintering the positive electrode of the waste lithium battery, and then dissolving and separating aluminum and lithium, specifically comprising: crushing the positive electrode of the waste lithium battery to a certain particle size with a crusher, adding a mixed solution of carbonate and ammonium salt to slurry; then placing the slurry in a converter for sintering, and after sintering, placing it in an alkali solution for dissolution; introducing the sintering tail gas into the dissolution solution, reacting at a certain temperature, and then adding a lithium precipitation agent, and obtaining a lithium precipitation liquid and a crude lithium salt after reaction filtration; adding seed crystals to the lithium precipitation liquid after evaporation and concentration to obtain aluminum hydroxide; according to the method for recovering aluminum and lithium elements by sintering according to the embodiment of the present invention, aluminum and lithium elements can be extracted in one step after sintering, thereby eliminating the influence of aluminum on subsequent wet purification processes. In addition, the CO2 generated by roasting can be introduced into the dissolution solution to adjust the temperature and pH of the dissolution solution, thereby achieving full resource utilization and less pollution.

[0032] The waste lithium battery positive electrodes applicable to the above method include but are not limited to ternary lithium battery positive electrodes, lithium carbonate battery positive electrodes, lithium iron phosphate battery positive electrodes, lithium cobalt oxide battery positive electrodes, etc. The positive electrode current collectors of these batteries are aluminum foil.

[0033] The present application is further described in detail below with reference to specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in this application.

[0034] Example 1

[0035] In this embodiment, the positive electrode of the waste ternary lithium battery is processed as follows:

[0036] (1) Grinding and slurrying step: Grind the waste lithium battery positive electrode to 100±50 mesh, take 100g of the pulverized material, 30g of ammonium chloride, and 15g of sodium carbonate, mix them evenly, and add water at a liquid-to-solid ratio of 1:3 to prepare a slurry;

[0037] (2) Sintering step: the slurry mixed uniformly in step (1) is placed in a converter, sintered at 650°C for 4 hours, and then cooled to room temperature to obtain a sintered material;

[0038] (3) Leaching step: take the sintered material obtained in step (2), add 5g / L sodium hydroxide aqueous solution at a liquid-to-solid ratio of 3:1, and leach at 85±5°C. After leaching for 3h, filter to obtain the dissolution solution and dissolution residue;

[0039] (4) lithium precipitation step: adding sodium phosphate as a lithium precipitation agent to the dissolution solution obtained in step (3) at a ratio of 1.3 times the theoretical coefficient of the lithium content, reacting the solution at 90±5°C for 2h, and then filtering to obtain a crude lithium precipitate and a lithium precipitation solution;

[0040] (5) Seeding step: the gas generated in step (2) is introduced into the lithium precipitation solution obtained in step (4) for 1 hour, and then evaporated and concentrated at 95±5°C to a concentration of Na≤80g / L and Li≥6g / L, and then aluminum hydroxide seeds with a seed ratio of 0.2 are slowly added at 65±5°C, and the mixture is fully stirred and induced for 5 hours. After the reaction, the aluminum hydroxide and the circulating mother liquor are obtained by filtration.

[0041] ICP detection showed that the lithium content in the lithium precipitate was 15.83%, the aluminum content in the aluminum hydroxide was 21.14%, the aluminum content in the slag from step 3 was 0.27%, the lithium content was 0.56%, the lithium recovery rate was 91.67%, and the aluminum recovery rate was 99.37%.

[0042] Example 2

[0043] In this embodiment, the positive electrode of the waste ternary lithium-ion battery is processed as follows:

[0044] (1) Grinding and slurrying step: Grind the waste lithium battery positive electrode to 100±50 mesh, take 100g of the pulverized material, 10g of ammonium chloride, and 10g of sodium carbonate, mix them evenly, and add water at a liquid-to-solid ratio of 1:2 to prepare a slurry;

[0045] (2) Sintering step: the slurry mixed uniformly in step (1) is placed in a converter, sintered at 500°C for 6 hours, and then cooled to room temperature to obtain a sintered material;

[0046] (3) Leaching step: Take the sintered material obtained in step (2), add 10 g / L sodium hydroxide aqueous solution at a liquid-to-solid ratio of 6:1, and leach at 85±5°C. After leaching for 3 hours, filter to obtain a dissolution solution and a dissolution residue;

[0047] (4) lithium precipitation step: adding sodium phosphate as a lithium precipitation agent to the dissolution solution obtained in step (3) at a ratio of 1.2 times the theoretical coefficient of the lithium content, reacting the solution at 90±5°C for 4 hours, and then filtering to obtain a crude lithium precipitate and a lithium precipitation solution;

[0048] (5) Seeding step: the gas generated in step (2) is introduced into the lithium precipitation solution obtained in step (4) for 2 hours, and then evaporated and concentrated at 95±5°C to Na≤80g / L, Li≥6g / L, and then aluminum hydroxide seeds with a seed ratio of 0.05 are slowly added at 65±5°C, and the mixture is fully stirred and induced for 5 hours. After the reaction, aluminum hydroxide and circulating mother liquor are obtained by filtration.

[0049] ICP detection showed that the lithium content in the lithium precipitate was 15.28%, the aluminum content in the aluminum hydroxide was 20.79%, the aluminum content in the slag dissolved in step 3 was 0.44%, and the lithium content was 0.71%. The recovery rate of lithium was 90.50%, and the recovery rate of aluminum was 98.73%.

[0050] Example 3

[0051] In this embodiment, the positive electrode of the waste ternary lithium-ion battery is processed as follows:

[0052] (1) Grinding and slurrying step: Grind the waste lithium battery positive electrode to 100±50 mesh, take 100g of the pulverized material, 50g of ammonium chloride, and 20g of sodium carbonate, mix them evenly, and add water at a liquid-to-solid ratio of 1:5 to prepare a slurry;

[0053] (2) Sintering step: placing the slurry mixed evenly in step (1) into a converter, sintering at 800°C for 2 hours, and then cooling to room temperature to obtain a sintered material;

[0054] (3) Leaching step: Take the sintered material obtained in step (2), add 8 g / L sodium hydroxide aqueous solution at a liquid-to-solid ratio of 3:1, and leach at 85±5°C. After leaching for 3 hours, filter to obtain the dissolution solution and dissolution residue;

[0055] (4) lithium precipitation step: adding sodium phosphate as a lithium precipitation agent to the dissolution solution obtained in step (3) at a ratio of 1.5 times the theoretical coefficient of the lithium content, reacting at 90±5°C for 1 hour, and then filtering to obtain a crude lithium precipitate and a lithium precipitation solution;

[0056] (5) Seeding step: the gas generated in step (2) is introduced into the lithium precipitation solution obtained in step (4) for 0.5 h, and then evaporated and concentrated at 95±5°C to a concentration of Na≤80 g / L and Li≥6 g / L, and then aluminum hydroxide seeds with a seed ratio of 0.1 are slowly added at 65±5°C, and the mixture is fully stirred and induced for 5 h. After the reaction, the aluminum hydroxide and the circulating mother liquor are obtained by filtration.

[0057] ICP detection showed that the lithium content in the lithium precipitate was 16.07%, the aluminum content in the aluminum hydroxide was 22.24%, the aluminum content in the slag from step 3 was 0.21%, the lithium content was 0.45%, the lithium recovery rate was 93.06%, and the aluminum recovery rate was 99.81%.

[0058] Example 4

[0059] In this embodiment, the positive electrode of the waste ternary lithium-ion battery is processed as follows:

[0060] (1) Grinding and slurrying step: Grind the waste lithium battery positive electrode to 100±50 mesh, take 100g of the pulverized material, 30g of ammonium sulfate, and 15g of sodium bicarbonate, mix them evenly, and add water at a liquid-to-solid ratio of 1:3 to prepare a slurry;

[0061] (2) Sintering step: the slurry mixed uniformly in step (1) is placed in a converter, sintered at 650°C for 4 hours, and then cooled to room temperature to obtain a sintered material;

[0062] (3) Leaching step: take the sintered material obtained in step (2), add 5g / L sodium carbonate aqueous solution at a liquid-to-solid ratio of 3:1, and leach at 85±5°C. After leaching for 3h, filter to obtain the dissolution solution and dissolution residue;

[0063] (4) lithium precipitation step: adding sodium carbonate as a lithium precipitation agent to the dissolution solution obtained in step (3) at a ratio of 1.3 times the theoretical coefficient of the lithium content, reacting the solution at 90±5°C for 2h, and filtering the solution to obtain a crude lithium carbonate precipitate and a lithium precipitation solution;

[0064] (5) Seeding step: the gas generated in step (2) is introduced into the lithium precipitation solution obtained in step (4) for 1 hour, and then evaporated and concentrated at 95±5°C to a concentration of Na≤80g / L and Li≥6g / L, and then aluminum hydroxide seeds with a seed ratio of 0.2 are slowly added at 65±5°C, and the mixture is fully stirred and induced for 5 hours. After the reaction, the aluminum hydroxide and the circulating mother liquor are obtained by filtration.

[0065] ICP detection showed that the lithium content in the lithium precipitate was 14.68%, the aluminum content in the aluminum hydroxide was 21.38%, the aluminum content in the slag dissolved in step 3 was 0.33%, the lithium content was 0.52%, the lithium recovery rate was 90.12%, and the aluminum recovery rate was 98.81%.

[0066] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for recovering aluminum and lithium elements by sintering, characterized in that: The following steps are involved: The crushing and slurrying step comprises crushing the positive electrode of the waste lithium battery to obtain a crushed material; preparing a slurry comprising the crushed material, ammonium salt and carbonate; Sintering step: sintering the slurry at a temperature of 500-800° C. to obtain a sintered material and sintered exhaust gas; Leaching step: using a dilute alkaline solution to leach the sintered material to obtain an eluate; Lithium precipitation step: adding a lithium precipitation agent to the dissolution solution to carry out lithium precipitation reaction to obtain lithium precipitate and lithium precipitation liquid; The seeding step comprises: introducing the sintering tail gas into the lithium precipitation solution, evaporating and concentrating the solution, adding seed crystals to the concentrated solution, and stirring to induce aluminum precipitation; In the pulverizing and slurrying step, the weight ratio of the pulverized material, the ammonium salt, and the carbonate is 1:(0.1-0.5):(0.1-0.2); the liquid-to-solid ratio in the slurry is 1:(2-5); The seeding step comprises: The sintering tail gas is passed into the lithium precipitation solution for 0.5 to 2 hours; Concentrating the lithium precipitation solution after the reaction at 90-100° C. by evaporation to obtain the concentrated solution; Aluminum hydroxide with a seed ratio of 0.05 to 0.2 is added to the concentrated solution as the seed crystal, and the aluminum precipitate is induced to precipitate under stirring at 50 to 70°C.

2. The method for recovering aluminum and lithium elements by sintering according to claim 1, characterized in that: In the crushing and slurrying step, the ammonium salt is selected from one or more of ammonium chloride, ammonium sulfate, and ammonium nitrate; and the carbonate is selected from one or more of sodium carbonate, sodium bicarbonate, potassium carbonate, and calcium carbonate.

3. The method for recovering aluminum and lithium elements by sintering according to claim 1, characterized in that: The particle size of the crushed material is 50 to 150 meshes.

4. The method for recovering aluminum and lithium elements by sintering according to claim 1 or 2, characterized in that: The sintering step comprises: The slurry is placed in a converter and sintered at a temperature of 500-800° C. for 2-6 hours, while collecting the sintering exhaust gas; After sintering is completed, the mixture is cooled to obtain the sintered material.

5. The method for recovering aluminum and lithium elements by sintering according to claim 1 or 2, characterized in that: In the leaching step, the dilute alkaline solution is selected from one or more aqueous solutions of sodium hydroxide, sodium carbonate, sodium bicarbonate, potassium hydroxide, and potassium carbonate.

6. The method for recovering aluminum and lithium elements by sintering according to claim 5, characterized in that: The weight concentration of the dilute alkaline solution is 5-10 g / L.

7. The method for recovering aluminum and lithium elements by sintering according to claim 5, characterized in that: In the leaching step, the liquid-to-solid ratio of the dilute alkali solution to the sintering material is (3-6):

1.

8. The method for recovering aluminum and lithium elements by sintering according to claim 7, characterized in that: The leaching temperature in the leaching step is 80-95° C., and the leaching time is 1-5 hours.

9. The method for recovering aluminum and lithium elements by sintering according to claim 1 or 2, characterized in that: In the lithium precipitation step, the lithium precipitation agent is selected from one or more of sodium carbonate, sodium phosphate, and sodium fluoride.

10. The method for recovering aluminum and lithium elements by sintering according to claim 1 or 2, characterized in that: The amount of the lithium precipitating agent added is 1.2 to 1.5 times the theoretical amount of Li element required in the dissolution solution.

11. The method for recovering aluminum and lithium elements by sintering according to claim 1 or 2, characterized in that: The temperature of the lithium precipitation reaction is 85-95° C. and the time is 1-4 hours.

12. The method for recovering aluminum and lithium elements by sintering according to claim 1, characterized in that: In the seeding step, after inducing the precipitation of the aluminum precipitate, the step of returning the remaining seeding mother liquor as part of the dilute alkaline solution for leaching the sintering material is also included.

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