Lithium recovery and purification method for waste ternary lithium battery

Abstract

The present invention discloses a lithium recovery and purification method for a waste ternary lithium battery, and belongs to the field of new energy. The method comprises: using a crude lithium extraction liquid obtained from a waste ternary lithium battery as feedstock of a material chamber in an n-stage mono- and multivalent rectification electrodialysis system; intercepting multivalent cations using the n-stage mono- and multivalent rectification electrodialysis system, and, by means of rectification and concentration, obtaining a lithium sulfate solution from water produced in an n-stage treatment rectification chamber; and, by means of a bipolar membrane electrodialysis system, converting the obtained lithium sulfate solution into a lithium hydroxide and sulfuric acid product, or adding sodium carbonate into the obtained lithium sulfate solution, then performing centrifugal precipitation, and carrying out leaching and drying processing to obtain a lithium carbonate product. The present invention, by means of using a combination of different membrane functions, does not require a reagent to extract lithium in a process of extracting lithium ions from a battery, thereby reducing environmental pollution. The n-stage mono- and multivalent rectification electrodialysis system has only one low-lithium, high-multivalent metal ion effluent produced in the material chamber, and the effluent of the rest of the system can be recycled and used in a system process, thereby implementing optimal utilization of lithium ions.

Description

A lithium recovery and purification method for waste ternary lithium batteries Technical Field

[0001] The present invention belongs to the field of new energy, and in particular relates to a method for recovering and purifying lithium from waste ternary lithium batteries. Background Art

[0002] Lithium-ion batteries primarily consist of a positive electrode, negative electrode, electrolyte, and copper foil. Common positive electrode materials include lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, lithium iron phosphate, and nickel-cobalt-aluminum ternary. Negative electrode materials are mostly graphite, but lithium metal, lithium alloys, and silicon-carbon negative electrodes are also available.

[0003] With the advancement of the new energy market, used batteries have begun to enter the recycling cycle. Traditional recycling methods all involve adding reagents, which require a large amount of reagents, resulting in poor purity of recycled lithium resources and generating a large amount of wastewater, which harms the environment.

[0004] At present, someone has proposed a lithium recovery process for waste lithium-ion batteries. First, the waste lithium-ion batteries are crushed and sorted to obtain positive and negative electrode active material powders. The positive and negative electrode active material powders obtained by sorting are then placed in a roasting furnace at a temperature of 600-650°C and roasted for a certain time at a certain mass ratio. The roasted product is then leached with oxalic acid solution and filtered to obtain nickel-cobalt-manganese slag and lithium oxalate solution. Finally, calcium hydroxide is added to the lithium oxalate solution to react, filtered to obtain lithium hydroxide solution and calcium oxalate, and the obtained calcium oxalate is added to sulfuric acid for acidification and filtered to obtain oxalic acid solution (CN201910689453.2). Its disadvantages are as follows:

[0005] (1) The recovered lithium hydroxide still contains some metal ions leached by acid and needs to be further purified;

[0006] (2) A large amount of calcium hydroxide is consumed and there is a risk of introducing calcium ions.

[0007] Therefore, a new lithium recovery and purification system and method for waste ternary lithium batteries are provided.

[0008] Summary of the Invention

[0009] The present invention provides a method for recovering and purifying lithium from waste ternary lithium batteries, overcoming the shortcomings and drawbacks mentioned above. The method can purify and concentrate the lithium and ultimately convert it into high-value lithium hydroxide or lithium carbonate products. The waste battery recycling system for producing lithium hydroxide includes: battery crushing and sorting, high-temperature acid spray roasting, water leaching, multivalent distillation electrodialysis, manganese sand filtration, and bipolar membrane electrodialysis; the waste battery production system for producing lithium carbonate includes: battery crushing and sorting, high-temperature acid spray roasting, water leaching, multivalent distillation electrodialysis, lithium precipitation with chemical addition, and leaching and purification.

[0010] The specific technical solutions adopted in the present invention are as follows:

[0011] The present invention provides a method for recovering and purifying lithium from waste ternary lithium batteries, which is as follows:

[0012] S1. Crushing and sorting the waste ternary lithium batteries to obtain positive and negative electrode active material powders;

[0013] S2, spraying acid and calcining the obtained positive and negative electrode active material powders at high temperature to obtain black powder;

[0014] S3, stirring the obtained black powder with water and soaking it in water, and filtering to obtain a crude lithium extraction solution;

[0015] S4, using the obtained crude lithium solution as the feed of the material chamber of the n-stage multivalent distillation electrodialysis system, n>1; using the n-stage multivalent distillation electrodialysis system to intercept multivalent cations, and obtaining a lithium sulfate solution after distillation and concentration in the produced water of the n-stage treatment distillation chamber;

[0016] The obtained lithium sulfate solution is then processed in step S5 or step S6;

[0017] S5, passing the obtained lithium sulfate solution through a manganese sand filter and converting it into lithium hydroxide and sulfuric acid products using a bipolar membrane electrodialysis system;

[0018] S6. Sodium carbonate is added to the obtained lithium sulfate solution, followed by centrifugal precipitation, and lithium carbonate product is obtained after rinsing and drying.

[0019] Preferably, the step S1 is specifically as follows:

[0020] The welding points in the waste ternary lithium batteries are milled by a milling machine, and then the battery guard plates are cut and removed, crushed and sorted, and finally the positive and negative active material powders of the battery are obtained.

[0021] Preferably, the step S2 is implemented in a roasting furnace, the roasting temperature is 600-1000° C., and the acid is concentrated sulfuric acid with a mass fraction of 98%.

[0022] Preferably, in step S3, the mass ratio of black powder to water is 1:(2-6), the stirring time is 0.5-2 hours, the static sedimentation time is 1 hour, and the supernatant after static sedimentation is filtered through ultrafiltration equipment to obtain a crude lithium solution.

[0023] Preferably, the n-stage multivalent distillation electrodialysis system comprises a positive electrode plate, a polar membrane separator, a polar membrane, an n-stage separator, an anion exchange membrane, an (n-1)-stage separator ... an anion exchange membrane, a first-stage separator, an anion exchange membrane, a 0-stage separator, a multivalent cation separation membrane, a first-stage separator, a multivalent cation separation membrane ... (n-1)-stage separator, a multivalent cation separation membrane, an n-stage separator, a polar membrane, a polar membrane separator, and a negative electrode plate. Based on the above arrangement order, the positive electrode plate, the polar membrane separator, and the polar membrane constitute a positive electrode chamber. , the polar membrane, the nth-stage separator and the anion exchange membrane constitute the nth-stage anion distillation chamber, the anion exchange membrane, the (n-1)th-stage separator and the anion exchange membrane constitute the (n-1)th-stage anion distillation chamber...the anion exchange membrane, the 0th-stage separator and a multivalent cation separation membrane constitute the material chamber, a multivalent cation separation membrane, the 1st-stage separator and a multivalent cation separation membrane constitute the 1st-stage cation distillation chamber, a multivalent cation separation membrane, the nth-stage separator and the polar membrane constitute the nth-stage cation distillation chamber, the polar membrane, the polar membrane separator and the negative electrode plate constitute the negative electrode chamber; the flow channels of the same-stage separators are consistent, and the flow chambers of different stages are independent of each other; the mth-stage anion distillation chamber and the mth-stage cation distillation chamber are connected and together constitute the mth-stage treatment distillation chamber, m∈[1,n].

[0024] Preferably, in the n-stage multivalent distillation electrodialysis system, the initial liquids of the positive electrode chamber and the negative electrode chamber are both lithium sulfate solutions or lithium chloride solutions with a mass fraction of 2% to 4%, and the initial liquids of the 1st to nth stage treatment distillation chambers are all lithium sulfate solutions with a mass fraction of 1% to 2%.

[0025] Preferably, in step S4, the produced water from the 1st to (n-1)th stage treatment and distillation chambers is returned to the material chamber; or the produced water from the pth stage treatment and distillation chamber is returned to the (p-1)th stage treatment and distillation chamber, p∈[2,n]; the produced water from the 1st stage treatment and distillation chamber is returned to the material chamber.

[0026] Preferably, the bipolar membrane electrodialysis system includes a positive electrode plate, a polar membrane separator, a polar membrane, a separator, a bipolar membrane, a separator, an anion exchange membrane, a separator, a cation exchange membrane, a separator, a bipolar membrane, a separator, an anion exchange membrane, a separator, a cation exchange membrane, a separator... a bipolar membrane, a separator, an anion exchange membrane, a separator, a cation exchange membrane, a separator, a polar membrane, a polar membrane separator, and a negative electrode plate arranged in sequence; based on the above arrangement order, adjacent bipolar membranes, separators and anion exchange membranes constitute an acid chamber, adjacent anion exchange membranes, separators and cation exchange membranes constitute a material chamber, adjacent cation exchange membranes, separators and bipolar membranes constitute an alkali chamber, and the polar membranes, separators and polar plates constitute a polar water chamber.

[0027] Preferably, in the bipolar membrane electrodialysis system, the lithium sulfate solution obtained in step S4 is used as the feed of the material chamber, the initial liquid of the polar water chamber is a lithium hydroxide solution or sodium hydroxide solution with a mass fraction of 2% to 4%, and the initial liquid of the acid chamber and the alkali chamber is pure water.

[0028] Preferably, the operating temperature of the n-stage multivalent distillation electrodialysis system and the bipolar membrane electrodialysis system are both 0-35°C.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) Compared with traditional battery recycling technology, there is no need to add a large amount of calcium hydroxide.

[0031] (2) Lithium ions in waste batteries can be directly made into selected products, including lithium hydroxide and lithium carbonate.

[0032] (3) Lithium ions can be concentrated during purification. Bipolar membrane electrodialysis can produce lithium hydroxide and sulfuric acid at the same time. The acid can be applied to the front-end process. The water produced by the lithium precipitation system can also be converted into acid and alkali reuse system through the bipolar membrane. The entire system can achieve maximum resource utilization.

[0033] (4) The water produced by each process can be recycled back to the front-end process to maximize the recovery of lithium. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIG1 is a schematic diagram of an n-stage multivalent distillation electrodialysis system, in which A is a multivalent cation exchange membrane (i.e., a multivalent cation separation membrane), B is an anion exchange membrane, and C is an electrode membrane;

[0035] Figure 2 is a schematic diagram of a bipolar membrane electrodialysis system, where D is a bipolar membrane, E is an anion exchange membrane, F is a cation exchange membrane, and G is a polar membrane;

[0036] FIG3 is a flow chart of producing lithium hydroxide from waste ternary lithium batteries;

[0037] Figure 4 is a flow chart of producing lithium carbonate from waste ternary lithium batteries. DETAILED DESCRIPTION

[0038] To provide a more intuitive understanding of the above-mentioned objectives, features, and advantages of the present invention, the following detailed description of the system's implementation is provided with reference to specific examples. The following description merely illustrates a specific example of the system's use. Any modifications or purification process additions made by those skilled in the art to the described specific implementation examples are within the scope of protection of the present invention, provided they do not deviate from the inventive concept or exceed the scope defined by the claims.

[0039] The present invention provides a method for recovering and purifying lithium from waste ternary lithium batteries, which is specifically as follows:

[0040] S1. Crushing and sorting the waste ternary lithium batteries to obtain positive and negative electrode active material powders.

[0041] As a preferred embodiment of the present invention, the steps are as follows:

[0042] The welding points in the waste ternary lithium batteries are milled by a milling machine, and then the battery guard plates are cut and removed, crushed and sorted, and finally the positive and negative active material powders of the battery are obtained.

[0043] S2. The positive and negative electrode active material powders obtained in step S1 are subjected to acid spraying and high-temperature roasting to obtain black powder.

[0044] As a preferred embodiment of the present invention, this step can be achieved by a roasting furnace. Specifically, the roasting temperature is 600-1000° C., and the acid is concentrated sulfuric acid with a mass fraction of 98%.

[0045] S3, stirring the black powder obtained in step S2 with water to soak in water, and filtering to obtain a crude lithium extraction solution.

[0046] As a preferred embodiment of the present invention, in this step, the mixing mass ratio of black powder to water is 1: (2 to 6), stirring is achieved by a mechanical stirring device, and the stirring time is 0.5 to 2 hours. After stirring, the static sedimentation time is 1 hour, and the supernatant after static sedimentation is filtered through an ultrafiltration device to obtain a crude lithium solution.

[0047] S4. Using the crude lithium solution obtained in step S3 as the feed for the material chamber of the n-stage multivalent distillation electrodialysis system, where n>1 and is an integer; using the n-stage multivalent distillation electrodialysis system to intercept multivalent cations, and obtaining a lithium sulfate solution that has been distilled and concentrated in the produced water of the n-stage treatment distillation chamber.

[0048] The obtained lithium sulfate solution is then processed in step S5 or step S6.

[0049] As a preferred embodiment of the present invention, as shown in FIG1 , an n-stage multivalent distillation electrodialysis system includes a positive electrode plate, an electrode membrane C, a multistage anion exchange membrane B, a multistage multivalent cation separation membrane A, an electrode membrane C, and a negative electrode plate, arranged in a sequentially spaced arrangement. It should be noted that, since the spacers between adjacent membrane layers in the n-stage multivalent distillation electrodialysis system primarily serve to support and separate them but do not play an essential role in ion exchange, they have been omitted in FIG1 for easier understanding. However, in actual applications, spacers are required between any adjacent membrane layers and between the electrode membranes and the electrode plates within the n-stage multivalent distillation electrodialysis system shown in FIG1 . Furthermore, the specific total number of membrane layers, n, in the multistage anion exchange membrane and the multistage multivalent cation separation membrane can be adjusted appropriately based on actual needs, with n being at least 2. The multistage anion exchange membrane comprises a total of n stages of anion exchange membranes arranged in a spaced arrangement, and the multistage multivalent cation separation membrane comprises a total of n stages of multivalent cation separation membranes arranged in a spaced arrangement. Therefore, in practical applications, the n-stage multivalent distillation electrodialysis system shown in FIG1 is composed of a positive electrode plate, a polar membrane separator, a polar membrane, an nth-stage separator, an anion exchange membrane, an (n-1)th-stage separator, ... an anion exchange membrane, a first-stage separator, an anion exchange membrane, a 0th-stage separator, a multivalent cation separation membrane, a first-stage separator, a multivalent cation separation membrane, ... an (n-1)th-stage separator, a multivalent cation separation membrane, an nth-stage separator, a polar membrane, a polar membrane separator, and a negative electrode plate, arranged in order. The 0th-stage separator is used to separate the anion exchange membrane from the multivalent cation separation membrane. Based on the above arrangement, the positive electrode plate, the polar membrane screen, and the polar membrane constitute the positive electrode compartment; the polar membrane, the nth-stage screen, and the anion exchange membrane constitute the nth-stage anion distillation compartment; the anion exchange membrane, the (n-1)th-stage screen, and the anion exchange membrane constitute the (n-1)th-stage anion distillation compartment... The anion exchange membrane, the 0th-stage screen, and a multivalent cation separation membrane constitute the feed compartment; the multivalent cation separation membrane, the 1st-stage screen, and a multivalent cation separation membrane constitute the 1st-stage cation distillation compartment; the multivalent cation separation membrane, the nth-stage screen, and the polar membrane constitute the nth-stage cation distillation compartment; and the polar membrane, the polar membrane screen, and the negative electrode plate constitute the negative electrode compartment. The flow paths of screens on the same level are consistent, and the flow paths of compartments on different levels are independent of each other. In other words, the arrangement order in an n-stage multivalent distillation electrodialysis system is: positive electrode compartment, nth-stage anion distillation compartment... 1st-stage anion distillation compartment, feed compartment, 1st-stage multivalent cation distillation compartment... nth-stage multivalent cation exchange compartment, negative electrode compartment. The mth stage anion distillation chamber and the mth stage cation distillation chamber are connected and together constitute the mth stage treatment distillation chamber, m∈[1,n]. The operating temperature of the n-stage multivalent distillation electrodialysis system is preferably 0-35°C.

[0050] Specifically, corresponding anion and cation distillation chambers use the same flow path screens and share the same storage tank and drive pump. For example, the nth-stage anion distillation chamber and the nth-stage cation distillation chamber share the same screen flow paths and are collectively referred to as the nth-stage process distillation chamber. The nth-stage drive pump drives the liquid in each chamber, and the tonnage barrel storing the mixed liquid is called the nth-stage distillation storage tank. Each stage of the process distillation chamber has different flow paths and is an independent unit. The positive and negative electrode chambers can share the same cathode water tank and cathode water pump, or they can be used independently.

[0051] Specifically, for an n-stage multivalent distillation electrodialysis system, the initial liquid in both the positive and negative electrode chambers is a 2% to 4% by mass lithium sulfate or lithium chloride solution, and the initial liquid in the first to nth treatment distillation chambers is a 1% to 2% by mass lithium sulfate solution. For applications requiring higher product purity, the produced water from the first to (n-1) treatment distillation chambers can be returned to the feed chamber. For applications requiring lower product purity, the produced water from the pth treatment distillation chamber can be returned to the (p-1)th treatment distillation chamber, where p∈[2,n]. The produced water from the first treatment distillation chamber is returned to the feed chamber.

[0052] In actual application, given the system direct current, under the condition of electric drive, the cations in the material chamber migrate toward the negative electrode. When passing through a multivalent ion exchange membrane, according to its selective permeability to ions, lithium ions are purified, and multivalent ions such as cobalt ions, aluminum ions, magnesium ions, calcium ions, manganese ions, silicon ions, and zinc ions are selectively blocked. After multi-stage blocking, purified lithium ions are finally obtained. Each anion distillation chamber stays adaptively according to the ion distribution of the cation distillation chamber, and together constitutes the corresponding treatment distillation chamber.

[0053] Through the interception of multivalent cations by a multivalent cation exchange membrane, the multi-stage distillation allows the selective rejection coefficient of the multivalent metal cations in the crude lithium solution obtained in step S3 to be amplified step by step. The n-stage anion and cation distillation chambers are mixed to obtain a purified lithium salt solution. In addition, by controlling the pure water replenishment rate, the lithium salt is concentrated in the n-stage distillation chamber. The water produced by the 1st to (n-1)th stage distillation chambers can be returned to the front-end material chamber for further lithium extraction and impurity removal.

[0054] After completing steps S1 to S4, the obtained lithium sulfate solution can be processed in step S5 or step S6 according to actual needs. S5 and S6 are two optional methods, and either one can be performed.

[0055] S5. The obtained lithium sulfate solution is passed through a manganese sand filter and converted into lithium hydroxide and sulfuric acid products using a bipolar membrane electrodialysis system, as shown in FIG3 .

[0056] There are numerous commercial products of bipolar membrane electrodialysis systems in the prior art, which can be used directly in theory. As a preferred embodiment of the present invention, as shown in Figure 2, the bipolar membrane electrodialysis system includes a positive electrode plate, a polar membrane G, a multi-stage membrane assembly (each stage membrane assembly is composed of a bipolar membrane D, an anion exchange membrane E, and a cation exchange membrane F arranged in sequence), a polar membrane G, and a negative electrode plate. It should also be noted that since the spacers between adjacent membrane layers in the bipolar membrane electrodialysis system mainly play a supporting and separating role, but have no essential effect on ion exchange, the spacers between adjacent membrane layers are omitted in Figure 2 for easier understanding. However, in actual applications, spacers need to be set between any adjacent membrane layers and between the polar membrane and the plate in the bipolar membrane electrodialysis system shown in Figure 2. In addition, the specific number of membrane assemblies in the multi-stage membrane assembly can be reasonably adjusted according to actual needs. Therefore, in practical applications, the bipolar membrane electrodialysis system shown in Figure 2 consists of a positive electrode plate, a bipolar membrane screen, a bipolar membrane G, a screen, a bipolar membrane D, a screen, an anion exchange membrane E, a screen, a cation exchange membrane F, a screen, a bipolar membrane D, a screen, an anion exchange membrane E, a screen, a cation exchange membrane F, a screen, ... bipolar membrane D, a screen, an anion exchange membrane E, a screen, a cation exchange membrane F, a screen, a bipolar membrane, a bipolar membrane screen, and a negative electrode plate. Based on this arrangement, adjacent bipolar membranes, screens, and anion exchange membranes form the acid chamber; adjacent anion exchange membranes, screens, and cation exchange membranes form the material chamber; adjacent cation exchange membranes, screens, and bipolar membranes form the base chamber; and the bipolar membranes, screens, and plates form the aqueous chamber. The material chamber, acid chamber, base chamber, and aqueous chamber are independent of each other. The operating temperature of the bipolar membrane electrodialysis system is preferably between 0 and 35°C. Supporting equipment includes circulating cooling water and a safety filter.

[0057] Specifically, in the bipolar membrane electrodialysis system, the lithium sulfate solution obtained in step S4 is used as the feed of the material chamber, the initial liquid of the polar water chamber is a lithium hydroxide solution or sodium hydroxide solution with a mass fraction of 2% to 4%, and the initial liquid of the acid chamber and the alkali chamber is pure water.

[0058] In actual application, a direct current is provided to the system. Under the action of the electric field, the lithium ions in the material chamber pass through the cation exchange membrane and combine with the hydroxide ions produced on the negative side of the bipolar membrane to form lithium hydroxide. The anions pass through the anion exchange membrane and combine with the hydrogen ions produced on the positive side of the bipolar membrane to form acid.

[0059] S6. Sodium carbonate is added to the obtained lithium sulfate solution, followed by centrifugal precipitation, and a lithium carbonate product is obtained after elution and drying operations, as shown in FIG4 .

[0060] As a preferred embodiment of the present invention, a lithium carbonate production system using a dosing method includes: a dosing pump, a stirring device, a centrifugal precipitator, a rinsing device, and a drying device. The dosing pump can be a peristaltic pump, a diaphragm pump, or a pressure injection pump. The stirring device includes a turbine agitator, a paddle agitator, a ribbon agitator, a hydraulic agitator, etc. The drying device includes a vacuum drying device and an oven drying device. The lithium precipitation reaction temperature is 60-90°C, the added reagent is a saturated sodium carbonate solution, and the stirring speed is 100-200 rpm.

[0061] The method and effects of the present invention will be further illustrated below through specific examples.

[0062] Example 1

[0063] This embodiment uses the above-mentioned waste ternary lithium battery recovery and purification method to produce lithium hydroxide. The specific method is as follows, as shown in Figure 3:

[0064] Use a milling machine to mill the welding points in the battery module; cut the battery guard plate and remove the battery guard plate; sort the positive and negative active material powders of the battery, and roast them at 900℃ with concentrated sulfuric acid for 10 hours. The sulfuric acid needs to be sprayed in an atomized manner. After roasting, collect the black powder, stir the black powder with pure water in a ratio of 1:2 and soak it in water for 2 hours. After multi-stage filtration, ultrafiltration is performed to obtain a crude lithium solution, in which the anion is SO4 2- , the cation composition is shown in Table 1.

[0065] Table 1 Cation composition in crude lithium solution

[0066] The crude lithium solution undergoes a three-stage, multivalent distillation electrodialysis system. The final cation composition of the tertiary product water is shown in Table 2. The structural components of the three-stage, multivalent distillation electrodialysis system, from left to right, are: positive electrode plate, polar membrane screen, polar membrane, third-stage screen, anion exchange membrane, second-stage screen, anion exchange membrane, first-stage screen, anion exchange membrane, screen, multivalent cation separation membrane, first-stage screen, multivalent cation separation membrane, second-stage screen, multivalent cation separation membrane, third-stage screen, polar membrane, polar membrane screen, and negative electrode plate. Three anion exchange membranes and three multivalent cation exchange membranes are required, along with the corresponding screens, to form a system unit. Polarization occurs at both ends of the plates, requiring two polar membranes (antioxidant membranes). A 1% (mass fraction) lithium sulfate solution is initially added to the distillation chamber as a receiving medium to improve current efficiency. The negative and positive electrode chambers share a common polar water tank, with 4% (mass fraction) lithium sulfate as the auxiliary electrolyte. Each chamber is internally circulated by an independent pump. Design parameters: partial pressure of one membrane is 0.5V, current density is 400~600A / m 2 , operating temperature 0 ~ 35 ° C. The water produced in the first and second distillation chambers overflows back to the material chamber.

[0067] Table 2 Cation composition of the three-stage distillation chamber

[0068] The tertiary produced water passes through the manganese sand filter to remove manganese ions. After entering the bipolar membrane, it is converted into 2mol / L lithium hydroxide and 1mol / L sulfuric acid. The bipolar membrane fresh water is used as the water supply for the third-stage multivalent distillation chamber. In the system, the bipolar membrane and the anion exchange membrane constitute the acid chamber, the anion exchange membrane and the cation exchange membrane constitute the material chamber, and the cation exchange membrane and the bipolar membrane constitute the alkali chamber. The above-mentioned purified lithium sulfate solution circulates in the material chamber through a circulation pump. The acid and alkali chambers can use pure water as the receiving medium. The polar water chamber adds a 3% by mass lithium hydroxide solution as an auxiliary medium. Each chamber circulates independently. Design parameters: a membrane partial pressure of 1V, a current density of 800A / m 2 , operating temperature 0 ~ 35 ℃, according to the above example, multiple system units can be inserted between the plates to increase the processing capacity of the equipment.

[0069] Example 2

[0070] This embodiment utilizes the above-mentioned waste ternary lithium battery recovery and purification method to produce lithium carbonate, as shown in Figure 4:

[0071] Use a milling machine to mill the welding points in the battery module; cut the battery guard plate and remove the battery guard plate; sort the positive and negative active material powders of the battery, and roast them at 920℃ with atomized concentrated sulfuric acid for 12 hours. After roasting, collect the black powder, stir the black powder with pure water in a ratio of 1:4 and soak it in water for 2 hours. After multi-stage filtration, ultrafiltration is performed to obtain a crude lithium solution, in which the anion is SO4 2- , the cation composition is shown in Table 3.

[0072] Table 3 Cation composition in crude lithium solution

[0073] The crude lithium solution undergoes three-stage, multivalent distillation electrodialysis. The final cation composition of the three-stage water product is shown in Table 4. The three-stage, multivalent distillation electrodialysis system consists of, from left to right, the positive electrode plate, polar membrane separator, polar membrane, third-stage separator, anion exchange membrane, second-stage separator, anion exchange membrane, first-stage separator, anion exchange membrane, separator, multivalent cation separation membrane, first-stage separator, multivalent cation separation membrane, second-stage separator, multivalent cation separation membrane, third-stage separator, polar membrane, polar membrane separator, and negative electrode plate. Three anion exchange membranes and three multivalent cation exchange membranes are required, along with the corresponding separators, to form a system unit. Polarization reactions occur across the plates, requiring two polar membranes (antioxidant membranes). A 1% by mass lithium sulfate solution is initially added to the distillation chamber as a receiving medium to improve current efficiency. The negative and positive electrode chambers share a common polar water tank, equipped with 4% by mass lithium sulfate as an auxiliary electrolyte. Internal circulation is achieved in each chamber via independent pumps. Design parameters: partial pressure of one membrane is 0.5V, current density is 400~600A / m2 , operating temperature 0 ~ 35℃.

[0074] Table 4 Cation composition of the three-stage distillation chamber

[0075] The tertiary produced water enters the dosing tank, where a saturated sodium carbonate solution is added as the reagent. A peristaltic pump is used for dosing, and mixing is achieved through a stirring device at 150 rpm. The lithium precipitation reaction temperature is 80°C, the sodium carbonate dosage is 1.2 times the theoretical amount, and the reaction time is 3 hours. The centrifuged lithium carbonate precipitate is continuously rinsed with water to remove impurities until it meets the specified standards.

[0076] Example 3

[0077] This embodiment uses the above-mentioned waste ternary lithium battery recovery and purification method to produce lithium hydroxide, which is specifically as follows, as shown in Figure 3:

[0078] Use a milling machine to mill the welding points in the battery module; cut the battery guard plate and remove the battery guard plate; sort the positive and negative active material powders of the battery, and roast them at 900℃ with concentrated sulfuric acid for 10 hours. The sulfuric acid needs to be sprayed in an atomized manner. After roasting, collect the black powder, stir the black powder with pure water in a ratio of 1:6 and soak it in water for 1 hour. After multi-stage filtration, ultrafiltration is performed to obtain a crude lithium solution, in which the anion is SO4 2- , the cation composition is shown in Table 5.

[0079] Table 5 Cation composition in crude lithium solution

[0080] The crude lithium solution undergoes three-stage, multivalent distillation electrodialysis. The final cation composition of the three-stage water product is shown in Table 6. The three-stage, multivalent distillation electrodialysis system consists of, from left to right, the positive electrode plate, polar membrane separator, polar membrane, third-stage separator, anion exchange membrane, second-stage separator, anion exchange membrane, first-stage separator, anion exchange membrane, separator, multivalent cation separation membrane, first-stage separator, multivalent cation separation membrane, second-stage separator, multivalent cation separation membrane, third-stage separator, polar membrane, polar membrane separator, and negative electrode plate. Three anion exchange membranes and three multivalent cation exchange membranes are required, along with the corresponding separators, to form a system unit. Polarization reactions occur across the plates, requiring two polar membranes (antioxidant membranes). A 1% by mass lithium sulfate solution is initially added to the distillation chamber as a receiving medium to improve current efficiency. The negative and positive chambers share a common polar water tank, equipped with 4% by mass lithium sulfate as an auxiliary electrolyte. Internal circulation is achieved in each chamber via independent pumps. Design parameters: partial pressure of one membrane is 0.5V, current density is 400~600A / m 2 The operating temperature is 0-35°C. The water produced by the first and second distillation chambers overflows back into the initial material chamber. The low-concentration lithium-containing water sample produced by the reaction in the third-stage polyvalent distillation electrodialysis material chamber is used as water for black powder leaching.

[0081] Table 6 Cation composition of the three-stage distillation chamber

[0082] The tertiary produced water passes through the manganese sand filter to remove the manganese ions. After entering the bipolar membrane, it can be converted into 2mol / L lithium hydroxide and 1mol / L sulfuric acid. The bipolar membrane fresh water is used as the water supply for the third-stage multivalent distillation chamber. In the system, the bipolar membrane and the anion exchange membrane constitute the acid chamber, the anion exchange membrane and the cation exchange membrane constitute the material chamber, and the cation exchange membrane and the bipolar membrane constitute the alkali chamber. The above-mentioned purified lithium sulfate solution circulates in the material chamber through a circulation pump. The acid and alkali chambers can use pure water as the receiving medium. The polar water chamber adds a 3% by mass lithium hydroxide solution as an auxiliary medium. Each chamber circulates independently. Design parameters: a membrane partial pressure of 1V, a current density of 800A / m 2 , operating temperature 0 ~ 35 ℃, according to the above example, multiple system units can be inserted between the plates to increase the processing capacity of the equipment.

[0083] This invention overcomes the drawbacks of conventional lithium battery recycling methods by utilizing a combination of different membrane functions. Furthermore, the lithium ion extraction process requires no reagents, requiring only water immersion, thus reducing environmental pollution. The system's effluent is exclusively treated with n-stage polyvalent distillation and electrodialysis to extract low-lithium and high-polyvalent metal ions. The remaining effluent can be recycled and reused within the system's processes, achieving optimal utilization of lithium ions.

[0084] The embodiment described above is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Persons skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, any technical solution obtained by equivalent substitution or equivalent transformation falls within the scope of protection of the present invention.

Claims

1. A method for recovering and purifying lithium from waste ternary lithium batteries, characterized in that: The details are as follows: S1. Crushing and sorting the waste ternary lithium batteries to obtain positive and negative electrode active material powders; S2, spraying acid and calcining the obtained positive and negative electrode active material powders at high temperature to obtain black powder; S3, stirring the obtained black powder with water and soaking it in water, and filtering to obtain a crude lithium extraction solution; S4, using the obtained crude lithium solution as feed for the material chamber of the n-stage multivalent distillation electrodialysis system, n>1; using the n-stage multivalent distillation electrodialysis system to intercept multivalent cations, and obtaining a lithium sulfate solution after distillation and concentration in the produced water of the n-stage treatment distillation chamber; The obtained lithium sulfate solution is then processed in step S5 or step S6; S5, passing the obtained lithium sulfate solution through a manganese sand filter and converting it into lithium hydroxide and sulfuric acid products using a bipolar membrane electrodialysis system; S6. Add sodium carbonate to the obtained lithium sulfate solution, centrifuge and precipitate, and obtain a lithium carbonate product after elution and drying.

2. The method for recovering and purifying lithium from waste ternary lithium batteries according to claim 1, characterized in that: The step S1 is specifically as follows: The welding points in the waste ternary lithium batteries are milled by a milling machine, and then the battery guard plates are cut and removed, crushed and sorted, and finally the positive and negative active material powders of the battery are obtained.

3. The method for recovering and purifying lithium from waste ternary lithium batteries according to claim 1, characterized in that: The step S2 is implemented by a roasting furnace, the roasting temperature is 600-1000° C., and the acid is concentrated sulfuric acid with a mass fraction of 98%.

4. The method for recovering and purifying lithium from waste ternary lithium batteries according to claim 1, characterized in that: In the step S3, the mass ratio of black powder to water is 1:(2-6), the stirring time is 0.5-2h, the static precipitation time is 1h, and the supernatant after static precipitation is filtered through an ultrafiltration device to obtain a crude lithium solution.

5. The method for recovering and purifying lithium from waste ternary lithium batteries according to claim 1, characterized in that: The n-stage multivalent distillation electrodialysis system comprises a positive electrode plate, a polar membrane separator, a polar membrane, an n-stage separator, an anion exchange membrane, an (n-1)-stage separator ... an anion exchange membrane, a first-stage separator, an anion exchange membrane, a 0-stage separator, a multivalent cation separation membrane, a first-stage separator, a multivalent cation separation membrane ... (n-1)-stage separator, a multivalent cation separation membrane, an n-stage separator, a polar membrane, a polar membrane separator, and a negative electrode plate arranged in sequence; based on the above arrangement order, the positive electrode plate, the polar membrane separator and the polar membrane constitute a positive electrode chamber, and the polar membrane, The nth-stage separator and the anion exchange membrane constitute the nth-stage anion distillation chamber, the anion exchange membrane, the (n-1)th-stage separator and the anion exchange membrane constitute the (n-1)th-stage anion distillation chamber...the anion exchange membrane, the 0th-stage separator and a multivalent cation separation membrane constitute the material chamber, a multivalent cation separation membrane, the 1st-stage separator and a multivalent cation separation membrane constitute the 1st-stage cation distillation chamber, a multivalent cation separation membrane, the nth-stage separator and the electrode membrane constitute the nth-stage cation distillation chamber, the electrode membrane, the electrode membrane separator and the negative electrode plate constitute the negative electrode chamber; the flow channels of the same-stage separators are consistent, and the flow chambers of different stages are independent of each other; the mth-stage anion distillation chamber and the mth-stage cation distillation chamber are connected and together constitute the mth-stage treatment distillation chamber, m∈[1,n].

6. The method for recovering and purifying lithium from waste ternary lithium batteries according to claim 1, characterized in that: In the n-stage multivalent distillation electrodialysis system, the initial liquids of the positive and negative electrode chambers are both 2% to 4% lithium sulfate solution or lithium chloride solution by mass, and the initial liquids of the 1st to nth stage treatment distillation chambers are all 1% to 2% lithium sulfate solution by mass.

7. The method for recovering and purifying lithium from waste ternary lithium batteries according to claim 1, characterized in that: In step S4, the water produced from the 1st to (n-1)th stage treatment and distillation chambers is returned to the material chamber; or the water produced from the pth stage treatment and distillation chamber is returned to the (p-1)th stage treatment and distillation chamber, p∈[2,n]; the water produced from the 1st stage treatment and distillation chamber is returned to the material chamber.

8. The method for recovering and purifying lithium from waste ternary lithium batteries according to claim 1, characterized in that: The bipolar membrane electrodialysis system includes a positive electrode plate, a polar membrane separator, a polar membrane, a separator, a bipolar membrane, a separator, an anion exchange membrane, a separator, a cation exchange membrane, a separator, a bipolar membrane, a separator, an anion exchange membrane, a separator, a cation exchange membrane, a separator... bipolar membrane, a separator, an anion exchange membrane, a separator, a cation exchange membrane, a separator, a polar membrane, a polar membrane separator, and a negative electrode plate arranged in sequence; based on the above arrangement order, adjacent bipolar membranes, separators and anion exchange membranes constitute an acid chamber, adjacent anion exchange membranes, separators and cation exchange membranes constitute a material chamber, adjacent cation exchange membranes, separators and bipolar membranes constitute an alkali chamber, and polar membranes, separators and polar plates constitute a polar water chamber.

9. The method for recovering and purifying lithium from waste ternary lithium batteries according to claim 1, characterized in that: In the bipolar membrane electrodialysis system, the lithium sulfate solution obtained in step S4 is used as the feed of the material chamber, the initial liquid of the polar water chamber is a lithium hydroxide solution or a sodium hydroxide solution with a mass fraction of 2% to 4%, and the initial liquid of the acid chamber and the alkali chamber is pure water.

10. The method for recovering and purifying lithium from waste ternary lithium batteries according to claim 1, characterized in that: The operating temperatures of the n-stage multivalent distillation electrodialysis system and the bipolar membrane electrodialysis system are both 0-35°C.

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