Method for recovering lithium from waste ternary battery powder by leaching after sulfurized and sulfated roasting

Abstract

The application provides a method for recovering lithium from waste ternary battery powder by pyrosulfation roasting and leaching of ferrous sulfide, which comprises the following steps: mixing iron disulfide and NCM ternary battery black powder to obtain mixed powder; roasting the mixed powder in an oxygen-containing atmosphere to obtain a roasting product; treating the roasting product by water leaching, and performing solid-liquid separation to obtain a leaching solution; adjusting the pH value of the leaching solution by an alkaline substance to obtain a purified solution; performing bipolar membrane electrodialysis on the purified solution to obtain sulfuric acid and a sodium-lithium mixed solution; introducing carbon dioxide into the sodium-lithium mixed solution to perform a carbonation reaction, and washing and drying the obtained lithium carbonate crude product to obtain a lithium carbonate product. The method uses iron disulfide as a low-cost sulfur source, lithium is preferentially converted into a water-soluble sulfate salt species, and nickel, cobalt and manganese are stably converted into insoluble oxides / needle-shaped phases, so that selective separation can be realized by water leaching, the use amount of sulfuric acid and reducing agent is saved compared with a traditional acid leaching method, and the method is a more economical lithium recovery scheme.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery recycling technology, and relates to a method for leaching and recovering lithium from waste ternary battery powder after ferrous sulfide sulfation roasting. Background Technology

[0002] NCM ternary lithium-ion batteries, with their advantages of high energy density and long cycle life, have dominated the power battery market, resulting in a large number of retired and used ternary batteries. These used ternary batteries contain various high-value metals such as lithium, cobalt, nickel, and manganese, with metal grades far exceeding those of natural ores. Efficient recycling of these batteries can effectively avoid the environmental risks posed by used batteries and has significant economic and social implications.

[0003] Currently, the recycling processes for spent ternary lithium batteries are mainly divided into pyrometallurgical and hydrometallurgical methods. Among them, hydrometallurgical processes have become the mainstream technology in the industry due to their advantages such as high metal recovery rates and good product purity. Traditional hydrometallurgical recycling processes typically use strong acids to directly leach valuable metals from the cathode material. To improve leaching efficiency, additional reducing agents such as sodium sulfite and hydrogen peroxide are needed to reduce high-valence cobalt and nickel to easily soluble low-valence states. However, acid leaching is costly; in addition, traditional acid leaching processes generate large amounts of acidic wastewater and waste residue, resulting in high costs for subsequent neutralization and environmental disposal.

[0004] To address the high cost of traditional acid leaching, the industry has begun exploring a process combining roasting pretreatment with selective leaching to reduce reagent consumption. Existing technologies have reported the use of sulfur-containing substances as reducing agents or sulfur sources for roasting pretreatment. Other existing technologies disclose methods for treating waste lithium cobalt oxide cathode materials using ferrous sulfide. However, lithium cobalt oxide and NCM ternary materials differ significantly in crystal structure, elemental composition, and chemical properties. The sulfidation and oxidation behavior of nickel, cobalt, and manganese in NCM materials is more complex, making this technology unsuitable for direct application in the recycling process of NCM ternary batteries.

[0005] Meanwhile, existing technologies do not incorporate bipolar membrane electrodialysis technology to achieve closed-loop recycling of acids and alkalis in the leachate, making it difficult to fundamentally solve the problem of high reagent consumption. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a method for leaching lithium from waste ternary battery powder through ferrous sulfide sulfation roasting. This method uses ferric sulfide as a low-cost sulfur source, preferentially converting lithium into water-soluble sulfate species, while nickel, cobalt, and manganese are stabilized into insoluble oxides / acicular phases. This allows for selective separation through water leaching, saving on sulfuric acid and reducing agent usage compared to traditional acid leaching methods, making it a more economical lithium recovery solution.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] This invention provides a method for leaching lithium from spent ternary lithium battery powder after ferrous sulfide sulfation roasting, the method comprising the following steps:

[0009] (1) Waste NCM ternary batteries are pretreated to obtain NCM ternary battery black powder;

[0010] (2) Mix iron disulfide with the NCM ternary battery black powder to obtain a mixed powder;

[0011] (3) The mixed powder is calcined in an oxygen-containing atmosphere to obtain the calcined product;

[0012] (4) The roasted product is treated with water immersion, and solid-liquid separation is performed to obtain leachate and filter residue;

[0013] (5) Adjust the pH value of the leachate using an alkaline substance to obtain a purified solution;

[0014] (6) The purified solution is subjected to bipolar membrane electrodialysis to obtain a mixture of sulfuric acid and sodium-lithium;

[0015] (7) Carbon dioxide is introduced into the sodium-lithium mixture to carry out a carbonization reaction. The resulting crude lithium carbonate is washed and dried to obtain the lithium carbonate product.

[0016] This invention addresses the technical challenge of existing sulfur-containing roasting technologies being unable to directly adapt to the complex multi-element, multi-valence reaction system of NCM ternary battery black powder by using iron disulfide as a low-cost sulfur source for sulfation roasting. It achieves the preferential and directional conversion of lithium to water-soluble sulfate and the simultaneous stabilization of nickel, cobalt, and manganese into insoluble oxides / acicular phases. This allows for efficient and selective separation of lithium from nickel, cobalt, and manganese through simple water leaching, fundamentally replacing the high-cost strong acid leaching and reducing agent addition processes in traditional wet processes, significantly reducing the consumption of sulfuric acid and reducing agents. Simultaneously, combined with bipolar membrane electrodialysis technology, it enables closed-loop recycling of acid and alkali resources in the leachate, further reducing chemical raw material input and waste treatment costs. This significantly improves the economic efficiency and environmental friendliness of the waste ternary battery recycling process, and results in high lithium leaching rate and excellent lithium carbonate product purity, demonstrating significant industrial application value.

[0017] In some embodiments, the pretreatment in step (1) includes: discharging the waste NCM ternary battery to a single cell voltage ≤0.5V, crushing it, heat-treating it at 400℃~600℃ for 1h~3h, and sieving it to obtain the NCM ternary battery black powder.

[0018] In some embodiments, the mass ratio of the NCM ternary battery black powder to the iron disulfide in step (2) is 10:3 to 10:7.

[0019] In some embodiments, the mixing method in step (2) includes dry milling;

[0020] The dry grinding speed is 200 r / min to 500 r / min, and the time is 10 s to 50 s.

[0021] In some embodiments, the heating rate of the calcination in step (3) is 5°C / min to 15°C / min.

[0022] In some embodiments, the calcination temperature in step (3) is 500°C to 900°C.

[0023] In some embodiments, the roasting time in step (3) is 2h to 10h.

[0024] In some embodiments, the liquid-to-solid ratio of the water immersion treatment in step (4) is 7:1 to 12:1, and the unit of the liquid-to-solid ratio is mL / g.

[0025] In some embodiments, the water immersion treatment in step (4) is carried out at a temperature of 75°C to 90°C.

[0026] In some embodiments, the water immersion treatment in step (4) takes 1.5h to 2.5h.

[0027] In some embodiments, the stirring rate of the water immersion treatment in step (4) is 200 r / min to 400 r / min.

[0028] In some embodiments, the alkaline substance in step (5) includes any one or a combination of at least two of sodium hydroxide, calcium hydroxide, ammonia, or sodium carbonate.

[0029] In some embodiments, in step (5), the pH of the leachate is adjusted to 4 to 6.5 using an alkaline substance.

[0030] In some embodiments, the current density of the bipolar membrane electrodialysis in step (6) is 50 A / m. 2 ~200A / m 2 The voltage is 10V~30V and the temperature is 25℃~40℃.

[0031] In some embodiments, the carbonization reaction in step (7) is carried out at a temperature of 25°C to 60°C.

[0032] In some embodiments, the pH value of the carbonization reaction in step (7) is 8 to 11.

[0033] In some embodiments, the washing in step (7) includes washing with deionized water at a temperature ≤80°C at least twice.

[0034] In some embodiments, the drying temperature in step (7) is 100°C to 120°C.

[0035] In some embodiments, the drying time in step (7) is 2h to 4h.

[0036] As a preferred embodiment of the method provided by the present invention, the method includes the following steps:

[0037] (1) Discharge the waste NCM ternary battery to a single cell voltage ≤0.5V, crush it, heat treat it at 400℃~600℃ for 1h~3h, and sieve it to obtain the NCM ternary battery black powder.

[0038] (2) Dry grinding and mixing of iron disulfide and the NCM ternary battery black powder to obtain a mixed powder;

[0039] The mass ratio of the NCM ternary battery black powder to the iron disulfide is 10:3 to 10:7.

[0040] The dry grinding speed is 200 r / min to 500 r / min, and the time is 10 s to 50 s;

[0041] (3) The mixed powder is calcined in an oxygen-containing atmosphere to obtain the calcined product;

[0042] The calcination heating rate is 5℃ / min~15℃ / min, the temperature is 500℃~900℃, and the time is 2h~10h;

[0043] (4) The roasted product is treated with water immersion, and solid-liquid separation is performed to obtain leachate and filter residue;

[0044] The liquid-to-solid ratio of the water immersion treatment is 7:1 to 12:1, and the unit of the liquid-to-solid ratio is mL / g;

[0045] The water immersion treatment is carried out at a temperature of 75℃~90℃ for 1.5h~2.5h, and at a stirring rate of 200r / min~400r / min.

[0046] (5) Adjust the pH of the leachate to 4-6.5 using an alkaline substance to obtain a purified solution;

[0047] The alkaline substance includes any one or a combination of at least two of sodium hydroxide, calcium hydroxide, ammonia, or sodium carbonate.

[0048] (6) The purified solution is subjected to bipolar membrane electrodialysis to obtain a mixture of sulfuric acid and sodium-lithium;

[0049] The current density of the bipolar membrane electrodialysis is 50 A / m. 2 ~200A / m 2Voltage is 10V~30V, temperature is 25℃~40℃;

[0050] (7) Carbon dioxide is introduced into the sodium-lithium mixture to carry out a carbonation reaction, and the crude lithium carbonate obtained is washed and dried to obtain the lithium carbonate product.

[0051] The carbonization reaction is carried out at a temperature of 25°C to 60°C and a pH value of 8 to 11.

[0052] The washing process includes washing with deionized water at a temperature ≤80°C at least twice;

[0053] The drying temperature is 100℃~120℃, and the time is 2h~4h.

[0054] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] This invention addresses the technical challenge of existing sulfur-containing roasting technologies being unable to directly adapt to the complex multi-element, multi-valence reaction system of NCM ternary battery black powder by using iron disulfide as a low-cost sulfur source for sulfation roasting. It achieves the preferential and directional conversion of lithium to water-soluble sulfate and the simultaneous stabilization of nickel, cobalt, and manganese into insoluble oxides / acicular phases. This allows for efficient and selective separation of lithium from nickel, cobalt, and manganese through simple water leaching, fundamentally replacing the high-cost strong acid leaching and reducing agent addition processes in traditional wet processes, significantly reducing the consumption of sulfuric acid and reducing agents. Simultaneously, combined with bipolar membrane electrodialysis technology, it enables closed-loop recycling of acid and alkali resources in the leachate, further reducing chemical raw material input and waste treatment costs. This significantly improves the economic efficiency and environmental friendliness of the waste ternary battery recycling process, and results in high lithium leaching rate and excellent lithium carbonate product purity, demonstrating significant industrial application value. Attached Figure Description

[0057] Figure 1 This invention provides a process flow diagram for the leaching and recovery of lithium from waste ternary battery powder by ferrous sulfide sulfation roasting. Detailed Implementation

[0058] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0059] The "range" disclosed in this invention can be defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific range. This type of range definition can include or exclude endpoints; any endpoint can be independently included or excluded, and they can be arbitrarily combined, meaning any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for specific parameters, it is understood that ranges of 60~110 and 80~120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and maximum range values ​​3, 4, and 5 are also listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this invention, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0" and "5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥2, it is equivalent to listing integers such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For instance, when a parameter is described as an integer selected from "2~10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0060] In this invention, "a combination of at least two" refers to a quantity greater than or equal to two, unless otherwise specified. For example, "any combination of one or at least two" means one or more or more items. It can be understood that when referring to "a combination of at least two," it refers to any suitable combination of multiple items, that is, a combination of "at least two" items carried out in a manner that does not conflict with and enables the implementation of this invention.

[0061] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0062] The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention can be combined with other embodiments.

[0063] Those skilled in the art will understand that the order in which the steps are written in the methods of the various embodiments does not imply a strict execution order. The detailed execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, but are preferably performed sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), meaning that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0064] In this invention, open-ended technical features or solutions described using terms such as "comprising" do not exclude additional members beyond those listed unless otherwise specified. They can be considered as providing both closed-ended features or solutions comprised of the listed members and open-ended features or solutions that include additional members beyond the listed members. For example, A includes a1, a2, and a3. Unless otherwise specified, it may also include other members or exclude additional members. This can be considered as providing both technical features or solutions where "A is composed of a1, a2, and a3" or "A is selected from a1, a2, and a3," and technical features or solutions where "A includes not only a1, a2, and a3, but also other members."

[0065] In this invention, unless otherwise specified, the features or solutions corresponding to "and / or" include any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" represents a group consisting of A, B, and "a combination of A and B". "Containing A and / or B" can mean "containing A, containing B, and containing A and B", or "containing A, containing B, or containing A and B", and can be appropriately understood according to the context.

[0066] Existing technologies disclose methods for treating waste lithium cobalt oxide cathode materials using ferrous sulfide. However, lithium cobalt oxide and NCM ternary materials differ significantly in crystal structure, elemental composition, and chemical properties. Lithium cobalt oxide has a regular layered LiCoO2 structure composed of a single element, with only +3 cobalt as the metal ion. It exhibits uniform chemical properties, and the sulfidation reaction process is simple and controllable. In contrast, NCM ternary materials are solid solutions of three transition metals: nickel, cobalt, and manganese. Ni is present in the crystal. 2+ Ni 3+Ni 4+ Co 3+ Mn 4+ It contains metal ions in various valence states, and the differences in ionic radii of different elements lead to inherent lattice distortions. Its redox thermodynamic and kinetic properties are fundamentally different from those of lithium cobalt oxide.

[0067] Moreover, during the oxidative roasting of sulfur-containing substances, there is a significant competitive relationship between the sulfidation and oxidation reactions of nickel, cobalt, and manganese in NCM materials. The sulfidation reaction barrier of manganese is much higher than that of cobalt and nickel, while the oxidation activity of nickel is significantly higher than that of cobalt and manganese. If the process parameters for lithium cobalt oxide recovery are directly adopted, incomplete lithium conversion may lead to a low leaching rate, or some nickel, cobalt, and manganese may be sulfided to form soluble sulfides, resulting in selective separation failure. Therefore, it is impossible to achieve efficient separation of lithium from nickel, cobalt, and manganese.

[0068] This invention provides a method for leaching lithium from spent ternary lithium battery powder after ferrous sulfide sulfation roasting, the method comprising the following steps:

[0069] (1) Waste NCM ternary batteries are pretreated to obtain NCM ternary battery black powder;

[0070] (2) Mix iron disulfide with the NCM ternary battery black powder to obtain a mixed powder;

[0071] (3) The mixed powder is calcined in an oxygen-containing atmosphere to obtain the calcined product;

[0072] (4) The roasted product is treated with water immersion, and solid-liquid separation is performed to obtain leachate and filter residue;

[0073] (5) Adjust the pH value of the leachate using an alkaline substance to obtain a purified solution;

[0074] (6) The purified solution is subjected to bipolar membrane electrodialysis to obtain a mixture of sulfuric acid and sodium-lithium;

[0075] (7) Carbon dioxide is introduced into the sodium-lithium mixture to carry out a carbonization reaction. The resulting crude lithium carbonate is washed and dried to obtain the lithium carbonate product.

[0076] This invention addresses the technical challenge of existing sulfur-containing roasting technologies being unable to directly adapt to the complex multi-element, multi-valence reaction system of NCM ternary battery black powder by using iron disulfide as a low-cost sulfur source for sulfation roasting. It achieves the preferential and directional conversion of lithium to water-soluble sulfate and the simultaneous stabilization of nickel, cobalt, and manganese into insoluble oxides / acicular phases. This allows for efficient and selective separation of lithium from nickel, cobalt, and manganese through simple water leaching, fundamentally replacing the high-cost strong acid leaching and reducing agent addition processes in traditional wet processes, significantly reducing the consumption of sulfuric acid and reducing agents. Simultaneously, combined with bipolar membrane electrodialysis technology, it enables closed-loop recycling of acid and alkali resources in the leachate, further reducing chemical raw material input and waste treatment costs. This significantly improves the economic efficiency and environmental friendliness of the waste ternary battery recycling process, and results in high lithium leaching rate and excellent lithium carbonate product purity, demonstrating significant industrial application value.

[0077] In some embodiments, the pretreatment in step (1) includes: discharging the waste NCM ternary battery to a single cell voltage ≤0.5V, crushing it, and then heat-treating it at 400℃~600℃ for 1h~3h to remove fluorine and degumming, and then sieving it to obtain the NCM ternary battery black powder.

[0078] In some embodiments, the mass ratio of the NCM ternary battery black powder to the iron disulfide in step (2) is 10:3 to 10:7, for example, it can be 10:3, 10:4, 10:5, 10:6 or 10:7, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0079] In some embodiments, the mixing method in step (2) includes dry milling;

[0080] The dry grinding speed is 200 r / min to 500 r / min, and the time is 10 s to 50 s.

[0081] The present invention utilizes dry grinding for mechanical activation, wherein the rotational speed of the dry grinding is 200 r / min to 500 r / min, for example, 200 r / min, 250 r / min, 300 r / min, 350 r / min, 400 r / min, 450 r / min or 500 r / min, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0082] In some embodiments, the heating rate of the roasting in step (3) is 5℃ / min to 15℃ / min, for example, it can be 5℃ / min, 6℃ / min, 8℃ / min, 10℃ / min, 12℃ / min, 13℃ / min, 14℃ / min or 15℃ / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0083] In some embodiments, the roasting temperature in step (3) is 500℃~900℃, for example, it can be 500℃, 550℃, 600℃, 650℃, 700℃, 750℃, 800℃, 850℃ or 900℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0084] In some embodiments, the roasting time in step (3) is 2h to 10h, for example, it can be 2h, 4h, 5h, 6h, 8h, 9h or 10h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0085] In some embodiments, the liquid-to-solid ratio of the water immersion treatment in step (4) is 7:1 to 12:1, for example, it can be 7:1, 8:1, 9:1, 10:1, 11:1 or 12:1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable. The unit of the liquid-to-solid ratio is mL / g.

[0086] In some embodiments, the water immersion treatment temperature in step (4) is 75°C to 90°C, for example, it can be 75°C, 76°C, 78°C, 80°C, 81°C, 82°C, 83°C, 84°C, 85°C or 90°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0087] In some embodiments, the water immersion treatment time in step (4) is 1.5h to 2.5h, for example, it can be 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, 2h, 2.2h, 2.4h or 2.5h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0088] In some embodiments, the stirring rate of the water immersion treatment in step (4) is 200 r / min to 400 r / min, for example, it can be 200 r / min, 250 r / min, 300 r / min, 350 r / min or 400 r / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0089] In some embodiments, the alkaline substance in step (5) includes any one or a combination of at least two of sodium hydroxide, calcium hydroxide, ammonia, or sodium carbonate.

[0090] In some embodiments, in step (5), an alkaline substance is used to adjust the pH of the leachate to 4 to 6.5, for example, it can be 4, 4.2, 4.5, 4.8, 5, 5.2, 5.4, 5.5, 5.6, 5.8, 6, 6.3 or 6.5, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0091] In some embodiments, the current density of the bipolar membrane electrodialysis in step (6) is 50 A / m. 2 ~200A / m 2 (For example, it could be 50A / m) 2 60A / m 2 80A / m 2 100A / m 2 120A / m 2 150A / m 2 160A / m 2 180A / m 2 Or 200A / m 2 (etc.), voltage is 10V~30V (e.g., 10V, 15V, 20V, 25V or 30V, etc.), temperature is 25℃~40℃ (e.g., 25℃, 28℃, 30℃, 32℃, 35℃, 36℃, 38℃ or 40℃, etc.).

[0092] In this invention, the device used for bipolar membrane electrodialysis can be a three-chamber structure, and the membrane stack is composed of bipolar membranes, cation exchange membranes and anion exchange membranes arranged alternately.

[0093] In some embodiments, the temperature of the carbonization reaction in step (7) is 25°C to 60°C, for example, it can be 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C or 60°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0094] In some embodiments, the pH value of the carbonization reaction in step (7) is 8 to 11, for example, it can be 8, 8.1, 8.2, 8.4, 8.5, 8.6, 8.8, 9, 9.5, 10, 10.5 or 11, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0095] In some embodiments, the washing in step (7) includes washing with deionized water at a temperature ≤80°C (e.g., 20°C, 30°C, 40°C, 50°C, 60°C, 65°C, 70°C, 75°C, or 80°C, etc.) at least twice.

[0096] In some embodiments, the drying temperature in step (7) is 100°C to 120°C (e.g., 100°C, 105°C, 110°C, 115°C, or 120°C).

[0097] In some embodiments, the drying time in step (7) is 2h to 4h (e.g., it can be 2h, 2.5h, 3h, 3.5h or 4h, etc.).

[0098] As a preferred embodiment of the method provided by the present invention, the method includes the following steps:

[0099] (1) Discharge the waste NCM ternary battery to a single cell voltage ≤0.5V, crush it, heat treat it at 400℃~600℃ for 1h~3h, and sieve it to obtain the NCM ternary battery black powder.

[0100] (2) Dry grinding and mixing of iron disulfide and the NCM ternary battery black powder to obtain a mixed powder;

[0101] The mass ratio of the NCM ternary battery black powder to the iron disulfide is 10:3 to 10:7.

[0102] The dry grinding speed is 200 r / min to 500 r / min, and the time is 10 s to 50 s;

[0103] (3) The mixed powder is calcined in an oxygen-containing atmosphere to obtain the calcined product;

[0104] The calcination heating rate is 5℃ / min~15℃ / min, the temperature is 500℃~900℃, and the time is 2h~10h;

[0105] (4) The roasted product is treated with water immersion, and solid-liquid separation is performed to obtain leachate and filter residue;

[0106] The liquid-to-solid ratio of the water immersion treatment is 7:1 to 12:1, and the unit of the liquid-to-solid ratio is mL / g;

[0107] The water immersion treatment is carried out at a temperature of 75℃~90℃ for 1.5h~2.5h, and at a stirring rate of 200r / min~400r / min.

[0108] (5) Adjust the pH of the leachate to 4-6.5 using an alkaline substance to obtain a purified solution;

[0109] The alkaline substance includes any one or a combination of at least two of sodium hydroxide, calcium hydroxide, ammonia, or sodium carbonate.

[0110] (6) The purified solution is subjected to bipolar membrane electrodialysis to obtain a mixture of sulfuric acid and sodium-lithium;

[0111] The current density of the bipolar membrane electrodialysis is 50 A / m. 2 ~200A / m 2 Voltage is 10V~30V, temperature is 25℃~40℃;

[0112] (7) Carbon dioxide is introduced into the sodium-lithium mixture to carry out a carbonation reaction, and the crude lithium carbonate obtained is washed and dried to obtain the lithium carbonate product.

[0113] The carbonization reaction is carried out at a temperature of 25°C to 60°C and a pH value of 8 to 11.

[0114] The washing process includes washing with deionized water at a temperature ≤80°C at least twice;

[0115] The drying temperature is 100℃~120℃, and the time is 2h~4h.

[0116] In this invention, waste NCM ternary batteries are discharged to a single cell voltage of ≤0.5V, crushed, and then heat-treated at 400℃~600℃ for 1h~3h. After sieving, NCM ternary battery black powder is obtained. The main components of the NCM ternary battery black powder, by mass percentage, include: 5.2wt%~7.8wt% lithium, 32.5wt%~58.6wt% nickel, 5.8wt%~19.7wt% cobalt, 10.3wt%~28.9wt% manganese, and the balance being impurities.

[0117] To clearly illustrate the technical solution of this invention, in the following embodiments and comparative examples, the source of NCM ternary battery black powder is as follows: waste NCM ternary batteries are discharged to a single cell voltage of 0.5V, crushed, heat-treated at 500℃ for 2 hours, and sieved to obtain NCM ternary battery black powder. The main components of the NCM ternary battery black powder, by mass percentage, are: 6.5wt% lithium, 33.2wt% nickel, 12.8wt% cobalt, 21.5wt% manganese, 0.8wt% aluminum, 0.3wt% copper, 0.1wt% iron, 2.5wt% carbon, and 1.2wt% fluorine.

[0118] Example 1

[0119] This embodiment provides a method for leaching and recovering lithium from waste ternary lithium battery powder through ferrous sulfide sulfation roasting. The process flow diagram is shown below. Figure 1 As shown, it includes:

[0120] S1. Dry grinding and mixing of iron disulfide and NCM ternary battery black powder to obtain mixed powder;

[0121] The mass ratio of the NCM ternary battery black powder to the iron disulfide is 10:5;

[0122] The dry grinding speed is 350 r / min and the time is 30 s;

[0123] S2. The mixed powder is calcined in air to obtain a calcined product;

[0124] The calcination process involves a heating rate of 10°C / min, a temperature of 800°C, and a time of 8 hours.

[0125] S3. The roasted product is treated with water immersion, and solid-liquid separation is performed to obtain leachate and filter residue;

[0126] The liquid-to-solid ratio of the water immersion treatment is 7:1, and the unit of the liquid-to-solid ratio is mL / g;

[0127] The water immersion treatment was carried out at a temperature of 90°C for 2.5 hours, with a stirring rate of 400 r / min.

[0128] S4. Adjust the pH of the leachate to 5.5 using sodium hydroxide, filter, and obtain purified solution;

[0129] S5. The purified solution is subjected to bipolar membrane electrodialysis to obtain a mixture of sulfuric acid and sodium-lithium solution;

[0130] The current density of the bipolar membrane electrodialysis is 100 A / m. 2 The voltage is 20V and the temperature is 35℃.

[0131] S6. Carbon dioxide is introduced into the sodium-lithium mixture to carry out a carbonation reaction. The resulting crude lithium carbonate is washed and dried to obtain the lithium carbonate product.

[0132] The carbonization reaction was carried out at a temperature of 50°C and a pH of 8.5.

[0133] The washing process involves washing twice with deionized water at 85°C.

[0134] The drying temperature is 110℃ and the time is 3 hours.

[0135] Example 2

[0136] This embodiment provides a method for leaching and recovering lithium from waste ternary lithium battery powder after ferrous sulfide sulfation roasting, including:

[0137] S1. Dry grinding and mixing of iron disulfide and NCM ternary battery black powder to obtain mixed powder;

[0138] The mass ratio of the NCM ternary battery black powder to the iron disulfide is 10:3;

[0139] The dry grinding speed is 200 r / min and the time is 10 s;

[0140] S2. The mixed powder is calcined in air to obtain a calcined product;

[0141] The calcination process involves a heating rate of 15°C / min, a temperature of 500°C, and a time of 2 hours.

[0142] S3. The roasted product is treated with water immersion, and solid-liquid separation is performed to obtain leachate and filter residue;

[0143] The liquid-to-solid ratio of the water immersion treatment is 8:1, and the unit of the liquid-to-solid ratio is mL / g;

[0144] The water immersion treatment was carried out at a temperature of 75°C for 1.5 hours, with a stirring rate of 200 r / min.

[0145] S4. Adjust the pH of the leachate to 4 using sodium hydroxide, filter, and obtain purified solution;

[0146] S5. The purified solution is subjected to bipolar membrane electrodialysis to obtain a mixture of sulfuric acid and sodium-lithium solution;

[0147] The current density of the bipolar membrane electrodialysis is 50 A / m. 2 The voltage is 10V and the temperature is 25℃.

[0148] S6. Carbon dioxide is introduced into the sodium-lithium mixture to carry out a carbonation reaction. The resulting crude lithium carbonate is washed and dried to obtain the lithium carbonate product.

[0149] The carbonization reaction was carried out at a temperature of 25°C and a pH of 8.

[0150] The washing process involves washing twice with deionized water at room temperature.

[0151] The drying temperature is 100℃ and the time is 4 hours.

[0152] Example 3

[0153] This embodiment provides a method for leaching and recovering lithium from waste ternary lithium battery powder after ferrous sulfide sulfation roasting, including:

[0154] S1. Dry grinding and mixing of iron disulfide and NCM ternary battery black powder to obtain mixed powder;

[0155] The mass ratio of the NCM ternary battery black powder to the iron disulfide is 10:7;

[0156] The dry grinding speed is 500 r / min and the time is 50 s;

[0157] S2. The mixed powder is calcined in air to obtain a calcined product;

[0158] The calcination process involves a heating rate of 5°C / min, a temperature of 900°C, and a time of 10 hours.

[0159] S3. The roasted product is treated with water immersion, and solid-liquid separation is performed to obtain leachate and filter residue;

[0160] The liquid-to-solid ratio of the water immersion treatment is 12:1, and the unit of the liquid-to-solid ratio is mL / g;

[0161] The water immersion treatment was carried out at a temperature of 85°C for 2.5 hours, with a stirring rate of 400 r / min.

[0162] S4. Adjust the pH of the leachate to 6.5 using sodium hydroxide, filter, and obtain purified solution;

[0163] S5. The purified solution is subjected to bipolar membrane electrodialysis to obtain a mixture of sulfuric acid and sodium-lithium solution;

[0164] The current density of the bipolar membrane electrodialysis is 200 A / m. 2 The voltage is 30V and the temperature is 40℃.

[0165] S6. Carbon dioxide is introduced into the sodium-lithium mixture to carry out a carbonation reaction. The resulting crude lithium carbonate is washed and dried to obtain the lithium carbonate product.

[0166] The carbonization reaction was carried out at a temperature of 60°C and a pH of 11.

[0167] The washing process involves washing twice with deionized water at 60°C.

[0168] The drying temperature is 120°C and the time is 2 hours.

[0169] Example 4

[0170] This embodiment provides a method for leaching and recovering lithium from waste ternary battery powder after ferrous sulfide sulfation roasting. Except for the mass ratio of NCM ternary battery black powder to iron disulfide being 10:1, the rest is the same as in Example 1.

[0171] Example 5

[0172] This embodiment provides a method for leaching and recovering lithium from waste ternary battery powder after ferrous sulfide sulfation roasting. Except for the mass ratio of NCM ternary battery black powder to iron disulfide being 10:10, the rest is the same as in Example 1.

[0173] Example 6

[0174] This embodiment provides a method for leaching and recovering lithium from waste ternary battery powder by calcination of ferrous sulfide and sulfation. Except for the calcination temperature of 450°C in step (3), the rest is the same as in embodiment 1.

[0175] Example 7

[0176] This embodiment provides a method for leaching and recovering lithium from waste ternary battery powder by ferrous sulfide sulfation roasting. Except for the roasting temperature of 950°C in step (3), the rest is the same as in embodiment 1.

[0177] Comparative Example 1

[0178] This comparative example provides a method for leaching and recovering lithium from waste ternary battery powder after ferrous sulfide sulfation and roasting. Except for replacing ferrous disulfide with ferrous sulfide by mass, the method is identical to Example 1, including:

[0179] S1. Dry grinding and mixing of ferrous sulfide and NCM ternary battery black powder to obtain mixed powder;

[0180] The mass ratio of the NCM ternary battery black powder to the ferrous sulfide is 10:5;

[0181] The dry grinding speed is 350 r / min and the time is 30 s;

[0182] S2. The mixed powder is calcined in air to obtain a calcined product;

[0183] The calcination process involves a heating rate of 10°C / min, a temperature of 800°C, and a time of 8 hours.

[0184] S3. The roasted product is treated with water immersion, and solid-liquid separation is performed to obtain leachate and filter residue;

[0185] The liquid-to-solid ratio of the water immersion treatment is 7:1, and the unit of the liquid-to-solid ratio is mL / g;

[0186] The water immersion treatment was carried out at a temperature of 90°C for 2.5 hours, with a stirring rate of 400 r / min.

[0187] S4. Adjust the pH of the leachate to 5.5 using sodium hydroxide, filter, and obtain purified solution;

[0188] S5. The purified solution is subjected to bipolar membrane electrodialysis to obtain a mixture of sulfuric acid and sodium-lithium solution;

[0189] The current density of the bipolar membrane electrodialysis is 100 A / m. 2 The voltage is 20V and the temperature is 35℃.

[0190] S6. Carbon dioxide is introduced into the sodium-lithium mixture to carry out a carbonation reaction. The resulting crude lithium carbonate is washed and dried to obtain the lithium carbonate product.

[0191] The carbonization reaction was carried out at a temperature of 50°C and a pH of 8.5.

[0192] The washing process involves washing twice with deionized water at 85°C.

[0193] The drying temperature is 110℃ and the time is 3 hours.

[0194] Comparative Example 2

[0195] This comparative example provides a method for leaching and recovering lithium from waste ternary battery powder after ferrous sulfide sulfation and roasting. Except for the absence of ferrous disulfide, the method is identical to that in Example 1, including:

[0196] S1. Dry grinding of NCM ternary battery black powder to obtain ground powder;

[0197] The dry grinding speed is 350 r / min and the time is 30 s;

[0198] S2. The ground powder is calcined in air to obtain a calcined product;

[0199] The calcination process involves a heating rate of 10°C / min, a temperature of 800°C, and a time of 8 hours.

[0200] S3. The roasted product is treated with water immersion, and solid-liquid separation is performed to obtain leachate and filter residue;

[0201] The liquid-to-solid ratio of the water immersion treatment is 7:1, and the unit of the liquid-to-solid ratio is mL / g;

[0202] The water immersion treatment was carried out at a temperature of 90°C for 2.5 hours, with a stirring rate of 400 r / min.

[0203] S4. Adjust the pH of the leachate to 5.5 using sodium hydroxide, filter, and obtain purified solution;

[0204] S5. The purified solution is subjected to bipolar membrane electrodialysis to obtain a mixture of sulfuric acid and sodium-lithium solution;

[0205] The current density of the bipolar membrane electrodialysis is 100 A / m. 2 The voltage is 20V and the temperature is 35℃.

[0206] S6. Carbon dioxide is introduced into the sodium-lithium mixture to carry out a carbonation reaction. The resulting crude lithium carbonate is washed and dried to obtain the lithium carbonate product.

[0207] The carbonization reaction was carried out at a temperature of 50°C and a pH of 8.5.

[0208] The washing process involves washing twice with deionized water at 85°C.

[0209] The drying temperature is 110℃ and the time is 3 hours.

[0210] Comparative Example 3

[0211] This comparative example provides a method for leaching lithium from ferrous sulfide sulfation roasted waste ternary battery powder. Except for the absence of bipolar membrane electrodialysis, the method involves directly adding 30wt% sodium carbonate solution to the purified solution for precipitation reaction (temperature 90℃, pH value 6.5). All other aspects are the same as in Example 1.

[0212] Performance Characterization

[0213] The lithium leaching rate, total nickel-cobalt-manganese leaching rate, and purity of the lithium carbonate product were measured using the methods provided in the above embodiments and comparative examples. The results are shown in Table 1.

[0214] The method for determining the lithium leaching rate is as follows: the concentration of lithium in the leachate is determined by ICP-OES, the mass of lithium in the leachate is obtained, and its mass percentage in the NCM ternary battery black powder is calculated.

[0215] The method for determining the total leaching rate of nickel, cobalt, and manganese is as follows: the concentrations of nickel, cobalt, and manganese in the leachate are determined by ICP-OES, the total mass of nickel, cobalt, and manganese in the leachate is obtained, and its mass percentage in the NCM ternary battery black powder is calculated.

[0216] The method for determining the purity of lithium carbonate products is as follows: the main content is determined by potentiometric titration using the standard method of GB / T 11075-2013 "Lithium Carbonate".

[0217] Table 1

[0218]

[0219] As can be seen from Examples 1 to 3 in Table 1, the method for leaching and recovering lithium from waste ternary battery powder by ferrous sulfide sulfation roasting provided by the present invention can achieve efficient and selective leaching of lithium, with the lithium leaching rate stable at over 87%, the total leaching rate of nickel, cobalt and manganese controlled at below 37%, and the purity of lithium carbonate products reaching over 98.5%, showing good prospects for industrial application.

[0220] A comparison of Examples 4 and 5 with Example 1 shows that when the amount of iron disulfide is too small, the amount of sulfate generated in the system is insufficient, which prevents lithium from being completely converted into water-soluble sulfate, resulting in a decrease in lithium leaching rate. When the amount of iron disulfide is too large, the excess sulfur will react with some nickel, cobalt, and manganese to form soluble sulfides, which will increase the total leaching rate of nickel, cobalt, and manganese and decrease the separation selectivity. At the same time, excess sulfur will introduce more impurities and reduce the purity of lithium carbonate products.

[0221] A comparison of Examples 6 and 7 with Example 1 shows that when the roasting temperature is too low, the kinetics of the oxidation and decomposition of iron disulfide and the sulfation reaction of lithium are slow, the reaction is incomplete, and the lithium leaching rate is low. When the roasting temperature is too high, the generated lithium sulfate will undergo partial thermal decomposition, and the material is prone to sintering and agglomeration, which hinders the leaching of internal lithium and leads to a decrease in the lithium leaching rate.

[0222] Comparison of Comparative Examples 1 and 2 with Example 1 shows that without the addition of ferric disulfide, lithium cannot be converted into water-soluble sulfate, resulting in insufficient lithium leaching rate and almost no recycling value. When ferric disulfide is replaced by ferrous sulfide of equal mass, the sulfur content of ferrous sulfide is lower and its oxidation reaction activity is insufficient, so it cannot provide enough active sulfur source for the sulfation of lithium, resulting in insufficient lithium leaching rate and failing to meet the requirements of industrial production.

[0223] As can be seen from the comparison between Comparative Example 3 and Example 1, when sodium carbonate precipitation is used directly, a large amount of sodium ion impurities are introduced into the system, which are difficult to completely remove by washing, resulting in a decrease in product purity. However, bipolar membrane electrodialysis technology achieves lithium enrichment and closed-loop acid-base circulation through ion selective migration, avoiding the introduction of additional sodium ions and finally obtaining battery-grade lithium carbonate products.

[0224] In summary, this invention addresses the technical challenge of existing sulfur-containing roasting technologies being unable to directly adapt to the complex multi-element, multi-valence reaction system of NCM ternary battery black powder by using iron disulfide as a low-cost sulfur source for sulfation roasting. It achieves the preferential and directional conversion of lithium to water-soluble sulfates and the simultaneous stabilization of nickel, cobalt, and manganese into insoluble oxides / acicular phases. This allows for efficient and selective separation of lithium from nickel, cobalt, and manganese through simple water leaching, fundamentally replacing the high-cost strong acid leaching and reducing agent addition processes in traditional wet processes, significantly reducing the consumption of sulfuric acid and reducing agents. Furthermore, by combining bipolar membrane electrodialysis technology, it achieves closed-loop recycling of acid and alkali resources in the leachate, further reducing the input of chemical raw materials and the cost of waste treatment. This significantly improves the economic efficiency and environmental friendliness of the waste ternary battery recycling process, and the high lithium leaching rate and excellent purity of the lithium carbonate product demonstrate its significant value for industrial application.

[0225] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for leaching and recovering lithium from waste ternary lithium battery powder after ferrous sulfide sulfation roasting, characterized in that, The method includes the following steps: (1) Waste NCM ternary batteries are pretreated to obtain NCM ternary battery black powder; (2) Mix iron disulfide with the NCM ternary battery black powder to obtain a mixed powder; (3) The mixed powder is calcined in an oxygen-containing atmosphere to obtain the calcined product; (4) The roasted product is treated with water immersion, and solid-liquid separation is performed to obtain leachate and filter residue; (5) Adjust the pH value of the leachate using an alkaline substance to obtain a purified solution; (6) The purified solution is subjected to bipolar membrane electrodialysis to obtain a mixture of sulfuric acid and sodium-lithium; (7) Carbon dioxide is introduced into the sodium-lithium mixture to carry out a carbonization reaction. The resulting crude lithium carbonate is washed and dried to obtain the lithium carbonate product.

2. The method according to claim 1, characterized in that, The pretreatment in step (1) includes: discharging the waste NCM ternary battery to a single cell voltage ≤0.5V, crushing it, heat-treating it at 400℃~600℃ for 1h~3h, and sieving it to obtain the NCM ternary battery black powder.

3. The method according to claim 1 or 2, characterized in that, In step (2), the mass ratio of the NCM ternary battery black powder to the iron disulfide is 10:3 to 10:

7.

4. The method according to any one of claims 1 to 3, characterized in that, The mixing method in step (2) includes dry grinding; The dry grinding speed is 200 r / min to 500 r / min, and the time is 10 s to 50 s.

5. The method according to any one of claims 1 to 4, characterized in that, The heating rate of the roasting in step (3) is 5℃ / min~15℃ / min; And / or, the calcination temperature in step (3) is 500℃~900℃; And / or, the roasting time in step (3) is 2h~10h.

6. The method according to any one of claims 1 to 5, characterized in that, The liquid-to-solid ratio of the water immersion treatment in step (4) is 7:1 to 12:1, and the unit of the liquid-to-solid ratio is mL / g; And / or, the water immersion treatment in step (4) is carried out at a temperature of 75°C to 90°C; And / or, the water immersion treatment in step (4) is carried out for 1.5h to 2.5h; And / or, the stirring rate of the water immersion treatment in step (4) is 200 r / min to 400 r / min.

7. The method according to any one of claims 1 to 6, characterized in that, The alkaline substance mentioned in step (5) includes any one or a combination of at least two of sodium hydroxide, calcium hydroxide, ammonia, or sodium carbonate; And / or, in step (5), the pH of the leachate is adjusted to 4 to 6.5 using an alkaline substance; And / or, the current density of the bipolar membrane electrodialysis in step (6) is 50 A / m 2 ~200 A / m 2 , the voltage is 10 V~30 V, and the temperature is 25℃~40℃.

8. The method according to any one of claims 1 to 7, characterized in that, The carbonization reaction in step (7) is carried out at a temperature of 25°C to 60°C. And / or, the pH value of the carbonization reaction in step (7) is 8 to 11.

9. The method according to any one of claims 1 to 8, characterized in that, The washing in step (7) includes washing with deionized water at a temperature ≤80℃ at least twice; And / or, the drying temperature in step (7) is 100℃~120℃; And / or, the drying time in step (7) is 2h~4h.

10. The method according to claim 1, characterized in that, The method includes the following steps: (1) Discharge the waste NCM ternary battery to a single cell voltage ≤0.5V, crush it, heat treat it at 400℃~600℃ for 1h~3h, and sieve it to obtain the NCM ternary battery black powder. (2) Dry grinding and mixing of iron disulfide and the NCM ternary battery black powder to obtain a mixed powder; The mass ratio of the NCM ternary battery black powder to the iron disulfide is 10:3 to 10:

7. The dry grinding speed is 200 r / min to 500 r / min, and the time is 10 s to 50 s; (3) The mixed powder is calcined in an oxygen-containing atmosphere to obtain the calcined product; The calcination heating rate is 5℃ / min~15℃ / min, the temperature is 500℃~900℃, and the time is 2h~10h; (4) The roasted product is treated with water immersion, and solid-liquid separation is performed to obtain leachate and filter residue; The liquid-to-solid ratio of the water immersion treatment is 7:1 to 12:1, and the unit of the liquid-to-solid ratio is mL / g; The water immersion treatment is carried out at a temperature of 75℃~90℃ for 1.5h~2.5h, and at a stirring rate of 200r / min~400r / min. (5) Adjust the pH of the leachate to 4-6.5 using an alkaline substance to obtain a purified solution; The alkaline substance includes any one or a combination of at least two of sodium hydroxide, calcium hydroxide, ammonia, or sodium carbonate. (6) The purified solution is subjected to bipolar membrane electrodialysis to obtain a mixture of sulfuric acid and sodium-lithium; The current density of the bipolar membrane electrodialysis is 50 A / m. 2 ~200A / m 2 Voltage is 10V~30V, temperature is 25℃~40℃; (7) Carbon dioxide is introduced into the sodium-lithium mixture to carry out a carbonation reaction, and the crude lithium carbonate obtained is washed and dried to obtain the lithium carbonate product. The carbonization reaction is carried out at a temperature of 25°C to 60°C and a pH value of 8 to 11. The washing process includes washing with deionized water at a temperature ≤80°C at least twice; The drying temperature is 100℃~120℃, and the time is 2h~4h.

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