Method for selective echelon separation of valuable metals from waste ternary lithium battery positive electrode material

Abstract

The invention belongs to the technical field of waste ternary lithium battery positive electrode material recovery, and particularly relates to a method for selectively separating valuable metal from a waste ternary lithium battery positive electrode material in an echelon mode. The method comprises the following steps: heating and mixing choline chloride, malonic acid and water, mixing the obtained eutectic solvent and the waste ternary lithium battery positive electrode material for nickel separation, then mixing the obtained leachate and an oxalic acid aqueous solution for cobalt separation, and then mixing the obtained leaching residue and an inorganic strong alkali solution for manganese separation. And finally, the obtained leachate contains the lithium element. According to the method provided by the invention, valuable metals in the positive electrode material of the waste ternary lithium battery can be selectively separated in an echelon manner, and the method has the advantages that the recovery efficiency is high; almost 100% of lithium, nickel, cobalt and manganese are recovered; the selectivity is good; the four valuable metals are separated in an echelon manner; the method is simple to operate, reduces energy consumption and belongs to a green solvent.

Description

Technical Field

[0001] The invention belongs to the technical field of recycling waste ternary lithium battery positive electrode materials, and specifically relates to a method for selectively and stepwisely separating valuable metals from waste ternary lithium battery positive electrode materials. Background Art

[0002] At present, with the surge in the number of waste lithium-ion batteries, the recycling and reuse of waste lithium-ion batteries is of great significance to environmental protection and resource recycling. Waste lithium-ion batteries contain various key metals, such as LiNi x Co y Mn 1-x- y O 2 Li (2-5wt%), Ni (5-12wt%) and Co (5-20wt%) in waste lithium-ion batteries. In addition, compared with natural ores, the metal content and grade in waste lithium-ion batteries are much higher, making them a high-quality mineral resource. Therefore, the recycling and reuse of waste lithium-ion batteries can not only reduce dependence on raw materials, but also bring significant environmental and economic benefits. The development of sustainable recycling methods for lithium-ion batteries can minimize adverse effects and ease restrictions on the supply chain of battery manufacturers. Therefore, there is an urgent need to develop sustainable recycling methods to recover key elements from potential valuable secondary resources.

[0003] However, due to the complex composition of lithium-ion batteries and the similar physical and chemical properties of transition metals, it is difficult to selectively separate them in the leached solution. At present, the leaching method at home and abroad usually adopts wet leaching, which uses inorganic acid or organic acid to uniformly leaching the ternary powder, and then extracts and separates it.

[0004] However, the above leaching separation method is cumbersome and costly, and the entire process requires repeated extraction and stripping stages, which is prone to intermediate contamination and difficult to selectively separate transition metals. Summary of the invention

[0005] The purpose of the present invention is to provide a method for selectively and stepwisely separating valuable metals from waste ternary lithium battery positive electrode materials. The method provided by the present invention can selectively and stepwisely separate valuable metals in waste ternary lithium battery positive electrode materials, and has the characteristics of high recovery efficiency: nearly 100% recovery of lithium, nickel, cobalt and manganese; good selectivity: four valuable metals are separated stepwise; simple operation, reduced energy consumption and the leaching solvent is a green solvent.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a method for selectively and stepwisely separating valuable metals from waste ternary lithium battery positive electrode materials, comprising the following steps:

[0008] heating and mixing choline chloride, malonic acid and water to obtain a deep eutectic solvent;

[0009] The low eutectic solvent and the waste ternary lithium battery positive electrode material are mixed to separate nickel, so as to obtain a first leaching residue and a first leaching solution; the first leaching residue contains nickel element; the waste ternary lithium battery positive electrode material is a nickel cobalt manganese oxide positive electrode material;

[0010] The first leaching solution and the oxalic acid aqueous solution are mixed to separate cobalt, thereby obtaining a second leaching residue and a second leaching solution; the second leaching residue contains the cobalt element;

[0011] The second leaching solution and an inorganic strong alkali solution are mixed to separate manganese, thereby obtaining a third leaching residue and a third leaching solution; the third leaching residue contains manganese elements, and the third leaching solution contains lithium elements.

[0012] Preferably, the molar ratio of choline chloride to malonic acid is 1:(0.5-2).

[0013] Preferably, the mass of the water accounts for 10-45% of the total mass of the choline chloride, malonic acid and water.

[0014] Preferably, the temperature of the heating and mixing is 60 to 80° C., and the time is 30 to 120 minutes.

[0015] Preferably, the ratio of the mass of the waste ternary lithium battery positive electrode material to the volume of the low eutectic solvent is (20-50) g:1L.

[0016] Preferably, the nickel separation temperature is 80-120° C., and the insulation time is 30-75 min.

[0017] Preferably, the molar concentration of the oxalic acid aqueous solution is 0.2 to 3 mol / L;

[0018] The volume ratio of the first leaching solution to the oxalic acid aqueous solution is 1:(0.5-4).

[0019] Preferably, the cobalt separation temperature is 60-100° C., and the insulation time is 30-120 min.

[0020] Preferably, the inorganic strong alkali solution is a sodium hydroxide solution, and the molar concentration of the inorganic strong alkali solution is 1 to 3 mol / L; the pH value of the manganese separation is ≥9.

[0021] Preferably, the pH value of the manganese separation is 9 to 12; the temperature is room temperature, and the time is 30 to 60 minutes.

[0022] The invention provides a method for selectively separating valuable metals from waste ternary lithium battery positive electrode materials in stages, comprising the following steps: heating and mixing choline chloride, malonic acid and water to obtain a low eutectic solvent; mixing the low eutectic solvent and the waste ternary lithium battery positive electrode materials to separate nickel to obtain a first leaching residue and a first leaching liquid; the first leaching residue contains nickel; the waste ternary lithium battery positive electrode material is a nickel cobalt manganese oxide positive electrode material (NCM ternary positive electrode material); mixing the first leaching liquid with an oxalic acid aqueous solution to separate cobalt to obtain a second leaching residue and a second leaching liquid; the second leaching residue contains cobalt; mixing the second leaching liquid with an inorganic strong alkali solution to separate manganese to obtain a third leaching residue and a third leaching liquid; the third leaching residue contains manganese, and the third leaching liquid contains lithium. The present invention uses a low eutectic solvent to selectively separate the valuable metals of the positive electrode materials of waste ternary lithium batteries in stages. The protons contained in malonic acid act as oxygen acceptors to efficiently leach metals. The chloride ions contained in choline chloride act as reducing agents and coordination ions, which are beneficial to metal leaching and adjusting coordination forms. In the nickel separation process of the present invention, the nickel ions and cobalt ions in the positive electrode materials of waste ternary lithium batteries have different coordination forms during the leaching process. The nickel ions appear in the form of positively charged hydrated ions and tend to combine with negatively charged malonate. In addition, when both nickel ions and cobalt ions form a five-membered ring chelate complex with malonic acid, the stability of the nickel complex is greater than that of the cobalt complex. Therefore, the nickel ions and the hydrogen bond donor malonic acid form dihydrated nickel malonate, which is an insoluble precipitate; choline chloride forms a more stable complex [CoCl 4 ] 2- Therefore, Co ions will not precipitate and enter the first leachate, thus achieving nickel ion separation. Then, in the process of cobalt separation, the present invention mixes the oxalic acid aqueous solution with the first leachate, and the water in the oxalic acid aqueous solution dilutes the first leachate, thereby changing the concentration of each ion in the first leachate, so as to achieve the effect of adjusting the coordination environment, so that the original [CoCl] in the first leachate 4 2- Converted to [Co(H 2 O) 6 ] 2+ , increasing its binding capacity with oxalate, while the complex formed by manganese ions and chloride ions [MnCl 4 ] 2- It is more stable and will not be affected by the ion concentration caused by dilution. Oxalate tends to combine with hydrated cobalt ions to form dihydrate cobalt oxalate precipitate, but it is difficult to compete with chloride ions for the coordination site of tetrachloromanganese, thereby achieving cobalt ion separation and manganese ions remaining in the second leachate. Finally, the present invention mixes the second leachate with an inorganic strong alkali solution, and the manganese ions form manganese hydroxide as an insoluble precipitate; lithium hydroxide is a water-soluble precipitate, thereby achieving manganese ion separation.

[0023] In summary, since the properties of transition metals are very similar, especially nickel and cobalt, it is very difficult to separate nickel and cobalt during the leaching process. The method provided by the present invention selectively separates valuable metals from waste ternary lithium battery positive electrode materials in stages. First, the separation of nickel and cobalt is achieved through a low eutectic solvent. Further, the four valuable metals in the waste ternary lithium battery positive electrode materials have good selective separation performance. The valuable metals in the waste ternary lithium battery positive electrode materials are selectively separated in stages, with high recovery efficiency: lithium, nickel, cobalt, and manganese are nearly 100% recovered; good selectivity: At the same time, the method provided by the present invention is simple to operate, reduces energy consumption, and is a green solvent. The technical problems such as long process flow, high chemical cost (extractant and energy) and environmental pollution in the current leaching and separation process of waste ternary lithium battery positive electrode materials are solved, and a feasible path is provided for the sustainable recovery of nickel cobalt manganese oxide positive electrode materials (NCM ternary positive electrode materials) today.

[0024] At the same time, the low eutectic solvent used in the present invention has the characteristics of simple synthesis method, low cost and environmental friendliness. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a data diagram showing the effect of metal ion concentration in the first leachate obtained in Example 1;

[0026] Figure 2 The XRD characterization diagrams of the raw material NCM811 and the residues after leaching at different temperatures in Example 1;

[0027] Figure 3 This is a data diagram showing the effect of metal ion concentration in the first leachate obtained in Example 2;

[0028] Figure 4 This is a data diagram showing the effect of metal ion concentration in the first leachate obtained in Example 3;

[0029] Figure 5 The data diagram of the effect of metal ion concentration in the second leachate obtained in Example 4;

[0030] Figure 6 This is an XRD characterization diagram of the second leaching residue obtained when separating cobalt at 60° C. in Example 4;

[0031] Figure 7 This is a data diagram showing the effect of metal ion concentration in the second leachate obtained in Example 5;

[0032] Figure 8 The data diagram of the effect of metal ion concentration in the second leachate obtained in Example 6;

[0033] Fig. 9This is a data diagram showing the effect of metal ion concentration in the second leachate obtained in Example 7;

[0034] Fig.10 This is a data diagram showing the effect of metal ion concentration in the third leachate obtained in Example 8;

[0035] Fig.11 This is an XRD characterization diagram of the calcined product obtained after high-temperature calcination of the third leached slag obtained in Example 8;

[0036] Fig.12 The data diagram of the effect of metal ion concentration in the three kinds of leaching residues obtained in Example 9;

[0037] Fig.13 The principle and flow chart of selective and stepwise separation of valuable metals from waste ternary lithium battery positive electrode materials provided by the present invention;

[0038] Fig.14 Comparison of the separation effects of low eutectic solvents obtained with different electron acceptors on nickel and cobalt. DETAILED DESCRIPTION

[0039] The present invention provides a method for selectively and stepwisely separating valuable metals from waste ternary lithium battery positive electrode materials, comprising the following steps:

[0040] heating and mixing choline chloride, malonic acid and water to obtain a deep eutectic solvent;

[0041] The low eutectic solvent and the waste ternary lithium battery positive electrode material are mixed to separate nickel, so as to obtain a first leaching residue and a first leaching solution; the first leaching residue contains nickel element; the waste ternary lithium battery positive electrode material is a nickel cobalt manganese oxide positive electrode material;

[0042] The first leaching solution and the oxalic acid aqueous solution are mixed to separate cobalt, thereby obtaining a second leaching residue and a second leaching solution; the second leaching residue contains the cobalt element;

[0043] The second leaching solution and an inorganic strong alkali solution are mixed to separate manganese, thereby obtaining a third leaching residue and a third leaching solution; the third leaching residue contains manganese elements, and the third leaching solution contains lithium elements.

[0044] In the present invention, unless otherwise specified, all preparation raw materials / components are commercially available products well known to those skilled in the art.

[0045] The present invention heats and mixes choline chloride, malonic acid and water to obtain a low eutectic solvent. In the present invention, the choline chloride serves as a hydrogen bond acceptor of the low eutectic solvent. Malonic acid serves as a hydrogen bond donor of the low eutectic solvent. The water serves as a diluent for the low eutectic solvent. The water is preferably deionized water. The molar ratio of the choline chloride and malonic acid is preferably 1:(0.5-2), specifically 1:1, 1:2 or 2:1. The mass of the water accounts for a percentage of the total mass of the choline chloride, malonic acid and water, preferably 10-45%, specifically 35% or 30%. The temperature of the heating and mixing is preferably 60-80°C, specifically 60°C or 70°C. The time of the heating and mixing is preferably 30-120min, specifically 30min, 45min, 90min or 120min. The heating and mixing is preferably carried out under stirring. The low eutectic solvent is in a uniform and clear state. In the present invention, the low eutectic solvent is a eutectic mixture composed of a hydrogen bond donor and a hydrogen bond acceptor with a higher original melting point. Due to the charge delocalization caused by the hydrogen bonding between the two, the eutectic solvent contains large, asymmetric ions and has low lattice energy. The present invention adopts the above-mentioned low eutectic solvent to achieve the stepwise selective separation of valuable metals in the positive electrode materials of waste ternary lithium batteries in the leaching stage.

[0046] After obtaining the low eutectic solvent, the present invention mixes the low eutectic solvent and the waste ternary lithium battery positive electrode material to separate nickel, and obtains a first leaching residue and a first leachate; the first leaching residue contains nickel element; the waste ternary lithium battery positive electrode material is a nickel cobalt manganese oxide positive electrode material (NCM ternary positive electrode material). In the present invention, the waste ternary lithium battery positive electrode material is in powder form. The mass ratio of the waste ternary lithium battery positive electrode material to the volume of the low eutectic solvent is preferably (20-50) g:1L, specifically 50g / L, 30g / L or 20g / L. The nickel separation is preferably carried out under oil bath conditions. The temperature of the nickel separation is preferably 80-120°C, specifically 80°C, 100°C or 120°C, and the insulation time is preferably 30-75min, specifically 30min, 45min, 60min or 75min. The nickel separation is preferably carried out under stirring conditions, and the stirring speed is preferably 400-500r / min. After the nickel separation is completed, a first separation slurry is obtained. In the present invention, the first separation slurry is preferably separated into a solid and a liquid to obtain a first leaching residue and a first leaching liquid. The solid-liquid separation is preferably performed by filtration. The nickel element in the first leaching residue mainly exists in the form of insoluble nickel dihydrate malonate.

[0047] After obtaining the first leachate, the present invention mixes the first leachate with an oxalic acid aqueous solution to separate cobalt, and obtains a second leach residue and a second leachate; the second leach residue contains cobalt element. In the present invention, the oxalic acid aqueous solution is preferably a solution of oxalic acid and deionized water. The molar concentration of the oxalic acid aqueous solution is preferably 0.2-3 mol / L, more preferably 0.25-1 mol / L, specifically 0.2 mol / L, 0.5 mol / L, 0.8 mol / L or 1 mol / L. The volume ratio of the first leachate to the oxalic acid aqueous solution is preferably 1:(0.5-4), more preferably 1:(1-3), specifically 1:1, 1:1, 1:2, 1:3 or 1:4. The cobalt separation is preferably carried out under the condition of an oil bath. The temperature of the cobalt separation is preferably 60-100°C, more preferably 60-80°C, specifically 60°C, 80°C or 100°C, and the insulation time is preferably 30-120min, specifically 30min, 45min, 60min, 90min or 120min. The cobalt separation is preferably carried out under stirring, and the stirring speed is preferably 400-500r / min. After the cobalt separation is completed, a second separation slurry is obtained. The present invention preferably separates the second separation slurry into solid and liquid to obtain a second leaching residue and a second leaching liquid. The solid-liquid separation is preferably filtration. The main form of the cobalt element in the second leaching residue is cobalt oxalate.

[0048] After obtaining the second leachate, the present invention mixes the second leachate with an inorganic strong alkali solution to separate manganese, and obtains a third leach residue and a third leach solution; the third leach residue contains manganese, and the third leach solution contains lithium. In the present invention, the inorganic strong alkali solution is preferably a sodium hydroxide solution. The sodium hydroxide solution is specifically a sodium hydroxide aqueous solution. The molar concentration of the inorganic strong alkali solution is preferably 1 to 3 mol / L, specifically 2 mol / L. The pH value of the manganese separation is preferably ≥9, and more preferably 9 to 12. The temperature of the manganese separation is preferably room temperature, and the time is preferably 30 to 120 min, and specifically preferably 2 h. After the manganese separation is completed, a third separation slurry is obtained. The present invention preferably separates the third separation slurry into solid and liquid to obtain a third leach residue and a third leach solution. The solid-liquid separation is preferably filtration. The third leach solution contains lithium hydroxide. The present invention preferably evaporates and crystallizes the third leach solution to recover the lithium element. The third leaching residue obtained after filtration is easily oxidized to form an amorphous structure. The present invention preferably calcines the third leaching residue to obtain a calcined product, and the phase composition of the calcined product is mainly Mn 3 O 4 .

[0049] The synthesis method of the low eutectic solvent used in the present invention is simple, low-cost and environmentally friendly, and has great potential for industrial application. The method provided by the present invention can selectively separate valuable metals in stages, and has the characteristics of high recovery efficiency: lithium, nickel, cobalt, and manganese are nearly 100% recovered; good selectivity: four valuable metals are separated in stages; simple operation, reduced energy consumption, and belonging to the characteristics of green solvents.

[0050] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0051] Example 1

[0052] This embodiment provides a method for selectively separating valuable metals from waste ternary lithium battery positive electrode materials using a deep eutectic solvent, which is specifically carried out in the following steps:

[0053] 1. Add a hydrogen bond acceptor (choline chloride), a hydrogen bond donor (malonic acid) and a diluent (deionized water) into a round-bottom flask, heat and stir until a uniform and clear deep eutectic solvent is obtained; wherein: the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:1, the mass concentration of the diluent in the deep eutectic solvent is 35%, the heating and stirring temperature is 60°C, the heating and stirring time is 90 min, and a uniform and clear deep eutectic solvent is obtained;

[0054] 2. The low eutectic solvent obtained in step 1 and the waste NCM811 ternary lithium battery positive electrode material powder are added to a round-bottom flask, wherein the amount of NCM ternary lithium battery positive electrode material powder added in the low eutectic solvent is 20 g / L, and the mixture is heated to 40°C, 60°C, 80°C, 100°C, 120°C and 140°C in an oil bath, respectively, and heated and stirred for 60 min at a speed of 400 r / min, thereby completing the selective leaching and separation of nickel and other metals in the ternary lithium battery positive electrode material powder. After filtration, the first leaching residue and the first leaching solution are obtained, and the concentration of each metal ion in the first leaching solution is determined by atomic absorption spectrometry. Figure 1 As shown, Figure 1 The results show that at 100° C., the low eutectic solvent prepared in Example 1 exhibits selectivity for nickel and lithium, cobalt and manganese, with lithium, manganese and cobalt being leached nearly 100%, while nickel is hardly leached.

[0055] The raw material NCM811 and the filtered residue obtained after leaching in step 2 at different temperatures (first leached residue) were characterized by X-ray diffraction (XRD). Figure 2Shown are the XRD of raw material NCM811 at 40℃, 80℃ and 100℃, PDF87-1562 is the standard card of lithium nickel cobalt oxide, PDF24-1804 is the standard card of nickel dihydrate malonate. The results show that the phase composition of the characteristic peak of the leached residue before 80℃ is mainly lithium nickel cobalt manganese oxide, and the phase composition of the characteristic peak of the solid phase residue after leaching at 80℃ and 100℃ in the deep eutectic solvent is nickel dihydrate malonate, which indicates that the main form of nickel after 80℃ is insoluble nickel dihydrate malonate.

[0056] Example 2

[0057] This embodiment provides a method for selectively separating valuable metals from waste ternary lithium battery positive electrode materials using a deep eutectic solvent, which is specifically carried out in the following steps:

[0058] 1. Add a hydrogen bond acceptor (choline chloride), a hydrogen bond donor (malonic acid) and a diluent (deionized water) into a round-bottom flask, heat and stir until a uniform and clear deep eutectic solvent is obtained; wherein: the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:2, the mass concentration of the diluent in the deep eutectic solvent is 30%, the heating and stirring temperature is 70°C, the heating and stirring time is 120 min, and a uniform and clear deep eutectic solvent is obtained;

[0059] 2. The low eutectic solvent obtained in step 1 and the waste NCM811 ternary lithium battery positive electrode material powder are added to a round-bottom flask, wherein the amount of NCM ternary lithium battery positive electrode material powder added to the low eutectic solvent is 20 g / L, and the mixture is heated and stirred at 100° C. in an oil bath for 15 min, 30 min, 45 min, 60 min, and 75 min, respectively, at a speed of 400 r / min, to complete the selective leaching and separation of nickel and other metals in the ternary lithium battery positive electrode material powder, and a first leaching solution is obtained after filtration, and an atomic absorption spectrometer is used to determine the concentration of each metal ion in the first leaching solution. Figure 3 As shown, Figure 3 The results show that the deep eutectic solvent prepared in this example exhibits the best selectivity for nickel and lithium cobalt manganese at 45 minutes (the leaching rate of nickel is very low, at 100°C, the leaching rate is 0.78% at 45 minutes, 0.6% at 60 minutes, and 0.25% at 75 minutes).

[0060] Example 3

[0061] This embodiment provides a method for selectively separating valuable metals from waste ternary lithium battery positive electrode materials using a deep eutectic solvent, which is specifically carried out in the following steps:

[0062] 1. Add a hydrogen bond acceptor (choline chloride), a hydrogen bond donor (malonic acid) and a diluent (deionized water) into a round-bottom flask, heat and stir until a uniform and clear deep eutectic solvent is obtained; wherein: the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 2:1, the mass concentration of the diluent in the deep eutectic solvent is 35%, the heating and stirring temperature is 60°C, the heating and stirring time is 120 min, and a uniform and clear deep eutectic solvent is obtained;

[0063] 2. The low eutectic solvent obtained in step 1 and the waste NCM811 ternary lithium battery positive electrode material powder are added to a round-bottom flask, wherein the dosage of the NCM ternary lithium battery positive electrode material powder in the low eutectic solvent is 200g / L, 100g / L, 50g / L, 30g / L, 20g / L and 15g / L, respectively. The mixture is heated and stirred at 100°C in an oil bath for 45min at a speed of 400r / min, thereby completing the selective leaching and separation of nickel and other metals in the ternary lithium battery positive electrode material powder. After filtration, a first leaching solution is obtained, and an atomic absorption spectrometer is used to determine the concentration of each metal ion in the first leaching solution. Figure 4 , Figure 4 The results showed that the deep eutectic solvent exhibited the best separation effect for nickel from lithium, cobalt and manganese at 20g / L.

[0064] Example 4

[0065] This embodiment provides a method for selectively separating valuable metals from waste ternary lithium battery positive electrode materials using a deep eutectic solvent, which is specifically carried out in the following steps:

[0066] 1. Add a hydrogen bond acceptor (choline chloride), a hydrogen bond donor (malonic acid) and a diluent (deionized water) into a round-bottom flask, heat and stir until a uniform and clear deep eutectic solvent is obtained; wherein: the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 2:1, the mass concentration of the diluent in the deep eutectic solvent is 20%, the heating and stirring temperature is 60°C, the heating and stirring time is 120 min, and a uniform and clear deep eutectic solvent is obtained;

[0067] 2. Add the low eutectic solvent obtained in step 1 and the waste NCM811 ternary lithium battery positive electrode material powder into a round-bottom flask, wherein the dosage of the NCM ternary lithium battery positive electrode material powder in the low eutectic solvent is 20 g / L, and heat and stir in an oil bath at 100° C. for 45 min at a speed of 400 r / min, thereby completing the selective leaching and separation of nickel and other metals in the ternary lithium battery positive electrode material powder, and obtaining a first leaching solution after filtration;

[0068] 3. Add the first leachate and oxalic acid solution into a round-bottom flask, the molar concentration of the oxalic acid solution is 0.5 mol / L, the volume ratio of the first leachate to the oxalic acid solution is 1:3, heat and stir in an oil bath at 40°C, 60°C, 80°C, and 100°C for 45 min at a speed of 400 r / min, and obtain the second leaching residue and the second leaching solution after filtration; use an atomic absorption spectrometer to determine the concentration of each metal ion in the second leaching solution, such as Figure 5 shown.

[0069] The residue after leaching at 60 °C (second leaching residue) was characterized by X-ray diffraction (XRD), as shown in Figure 6 The figure shows the XRD of the leached residue obtained by adding oxalic acid solution. PDF25-0521 is the standard card of cobalt oxalate. Figure 6 The results showed that the phase composition of the characteristic peak of the leached residue was mainly cobalt oxalate, which indicated that the main form of precipitated cobalt after adding oxalic acid solution was cobalt oxalate.

[0070] Example 5

[0071] This embodiment provides a method for selectively separating valuable metals from waste ternary lithium battery positive electrode materials using a deep eutectic solvent, which is specifically carried out in the following steps:

[0072] 1. Add a hydrogen bond acceptor (choline chloride), a hydrogen bond donor (malonic acid) and a diluent (deionized water) into a round-bottom flask, heat and stir until a uniform and clear deep eutectic solvent is obtained; wherein: the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 2:1, the mass concentration of the diluent in the deep eutectic solvent is 20%, the heating and stirring temperature is 60°C, the heating and stirring time is 120 min, and a uniform and clear deep eutectic solvent is obtained;

[0073] 2. Add the low eutectic solvent obtained in step 1 and the waste NCM811 ternary lithium battery positive electrode material powder into a round-bottom flask, wherein the dosage of the NCM ternary lithium battery positive electrode material powder in the low eutectic solvent is 20 g / L, and heat and stir in an oil bath at 100° C. for 45 min at a speed of 400 r / min, thereby completing the selective leaching and separation of nickel and other metals in the ternary lithium battery positive electrode material powder, and obtaining a first leaching solution after filtration;

[0074] 3. Add the first leachate and oxalic acid solution into a round-bottom flask, the molar concentration of the oxalic acid solution is 0.5 mol / L, the volume ratio of the first leachate to the oxalic acid solution is 1:3, heat and stir at 80°C in an oil bath for 30 min, 45 min, 60 min, 90 min, 120 min, and a speed of 400 r / min, and obtain the second leaching residue and the second leaching solution after filtration; use an atomic absorption spectrometer to determine the concentration of each metal ion in the second leaching solution, such as Figure 7 shown.

[0075] Example 6

[0076] This embodiment provides a method for selectively separating valuable metals from waste ternary lithium battery positive electrode materials using a deep eutectic solvent, which is specifically carried out in the following steps:

[0077] 1. Add a hydrogen bond acceptor (choline chloride), a hydrogen bond donor (malonic acid) and a diluent (deionized water) into a round-bottom flask, heat and stir until a uniform and clear deep eutectic solvent is obtained; wherein: the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 2:1, the mass concentration of the diluent in the deep eutectic solvent is 20%, the heating and stirring temperature is 60°C, the heating and stirring time is 120 min, and a uniform and clear deep eutectic solvent is obtained;

[0078] 2. Add the low eutectic solvent obtained in step 1 and the waste NCM811 ternary lithium battery positive electrode material powder into a round-bottom flask, wherein the dosage of the NCM ternary lithium battery positive electrode material powder in the low eutectic solvent is 20 g / L, and heat and stir in an oil bath at 100° C. for 45 min at a speed of 400 r / min, thereby completing the selective leaching and separation of nickel and other metals in the ternary lithium battery positive electrode material powder, and obtaining a first leaching solution after filtration;

[0079] 3. Add the first leachate and oxalic acid solution into a round-bottom flask, the molar concentrations of the oxalic acid solution are 0.2 mol / L, 0.5 mol / L, 0.8 mol / L, and 1 mol / L, respectively, and the volume ratio of the first leachate to the oxalic acid solution is 1:3. Heat and stir in an oil bath at 60°C for 90 min at a speed of 400 r / min. After filtering, obtain the second leaching residue and the second leaching solution; use an atomic absorption spectrometer to determine the concentration of each metal ion in the second leaching solution, such as Figure 8 shown.

[0080] Example 7

[0081] This embodiment provides a method for selectively separating valuable metals from waste ternary lithium battery positive electrode materials using a deep eutectic solvent, which is specifically carried out in the following steps:

[0082] 1. Add a hydrogen bond acceptor (choline chloride), a hydrogen bond donor (malonic acid) and a diluent (deionized water) into a round-bottom flask, heat and stir until a uniform and clear deep eutectic solvent is obtained; wherein: the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 2:1, the mass concentration of the diluent in the deep eutectic solvent is 20%, the heating and stirring temperature is 60°C, the heating and stirring time is 120 min, and a uniform and clear deep eutectic solvent is obtained;

[0083] 2. Add the low eutectic solvent obtained in step 1 and the waste NCM811 ternary lithium battery positive electrode material powder into a round-bottom flask, wherein the dosage of the NCM ternary lithium battery positive electrode material powder in the low eutectic solvent is 20 g / L, and heat and stir in an oil bath at 100° C. for 45 min at a speed of 400 r / min, thereby completing the selective leaching and separation of nickel and other metals in the ternary lithium battery positive electrode material powder, and obtaining a first leaching solution after filtration;

[0084] 3. Add the first leachate and oxalic acid solution into a round-bottom flask, the molar concentration of the oxalic acid solution is 0.5 mol / L, the volume ratio of the first leachate to the oxalic acid solution is 1:1, 1:2, 1:3, 1:4, respectively, heat and stir in an oil bath at 60°C for 90 min, and the speed is 400 r / min. After filtering, the second leach residue and the second leach solution are obtained; the concentration of each metal ion in the second leach solution is determined by atomic absorption spectrometry, such as Fig. 9 shown.

[0085] Example 8

[0086] This embodiment provides a method for selectively separating valuable metals from waste ternary lithium battery positive electrode materials using a deep eutectic solvent, which is specifically carried out in the following steps:

[0087] 1. Add a hydrogen bond acceptor (choline chloride), a hydrogen bond donor (malonic acid) and a diluent (deionized water) into a round-bottom flask, heat and stir until a uniform and clear deep eutectic solvent is obtained; wherein: the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 2:1, the mass concentration of the diluent in the deep eutectic solvent is 20%, the heating and stirring temperature is 60°C, the heating and stirring time is 120 min, and a uniform and clear deep eutectic solvent is obtained;

[0088] 2. Add the low eutectic solvent obtained in step 1 and the waste NCM811 ternary lithium battery positive electrode material powder into a round-bottom flask, wherein the dosage of the NCM ternary lithium battery positive electrode material powder in the low eutectic solvent is 20 g / L, and heat and stir in an oil bath at 100° C. for 45 min at a speed of 400 r / min, thereby completing the selective leaching and separation of nickel and other metals in the ternary lithium battery positive electrode material powder, and obtaining a first leaching solution after filtration;

[0089] 3. Add the first leachate and oxalic acid solution into a round-bottom flask, the molar concentration of the oxalic acid solution is 0.5 mol / L, the volume ratio of the first leachate to the oxalic acid solution is 1:3, respectively, heat and stir in an oil bath at 60°C for 90 min, at a speed of 400 r / min, and obtain the second leach residue and the second leach solution after filtering;

[0090] Fourth, the second leaching solution was mixed with 2 mol / L sodium hydroxide solution at room temperature and added to a beaker, the pH was adjusted to 12, and the mixture was stirred and precipitated at 400 r / min at room temperature for 2 hours; the separation of manganese and lithium in the leaching solution was completed; after filtration, the third leaching residue and the third leaching solution were obtained, and the concentration of each metal ion in the third leaching solution was determined by atomic absorption spectrometer. Fig.10 .

[0091] The residue after leaching (third leaching residue) was characterized by X-ray diffraction (XRD). The precipitate just taken out was easily oxidized to form an amorphous structure and needed to be calcined at high temperature (800℃, 2h). Fig.11 The figure shows the XRD of the leached residue obtained after calcination. PDF24-0734 is Mn 3 O 4 The results show that the phase composition of the characteristic peak of the leached residue is mainly Mn 3 O 4 This indicates that after adding sodium hydroxide solution to the second leaching solution, the third leaching residue obtained is amorphous manganese hydroxide, manganese oxyhydroxide, dihydrated manganese oxide (MnO(OH) 2 ) and manganese oxide (Mn 2 O 3 ),

[0092] Example 9

[0093] This embodiment provides a method for selectively separating valuable metals from waste ternary lithium battery positive electrode materials using a deep eutectic solvent, which is specifically carried out in the following steps:

[0094] 1. Add a hydrogen bond acceptor (choline chloride), a hydrogen bond donor (malonic acid) and a diluent (deionized water) into a round-bottom flask, heat and stir until a uniform and clear deep eutectic solvent is obtained; wherein: the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 2:1, the mass concentration of the diluent in the deep eutectic solvent is 20%, the heating and stirring temperature is 60°C, the heating and stirring time is 120 min, and a uniform and clear deep eutectic solvent is obtained;

[0095] 2. Add the low eutectic solvent obtained in step 1 and the waste NCM811 ternary lithium battery positive electrode material powder into a round-bottom flask, wherein the dosage of the NCM ternary lithium battery positive electrode material powder in the low eutectic solvent is 20 g / L, and heat and stir in an oil bath at 100° C. for 45 min at a speed of 400 r / min, thereby completing the selective leaching and separation of nickel and other metals in the ternary lithium battery positive electrode material powder, and obtaining the first leached residue after filtration, which is digested and tested for purity;

[0096] 3. Add the first leachate and oxalic acid solution into a round-bottom flask, the molar concentration of the oxalic acid solution is 0.5 mol / L, the volume ratio of the first leachate to the oxalic acid solution is 1:3, respectively, heat and stir at 80°C in an oil bath for 90 min, respectively, at a speed of 400 r / min, and obtain the second leach residue after filtration, which is digested and tested for purity;

[0097] Fourth, the second leachate was mixed with 2 mol / L sodium hydroxide solution at room temperature and added to a beaker, the pH was adjusted to 12, and the mixture was stirred and precipitated at 400 r / min at room temperature for 2 h; the separation of manganese and lithium in the leachate was completed; after filtration, the third leach residue was obtained, which was digested and tested for purity, such as Fig.12 .

[0098] Comparative Example 1

[0099] The preparation method is basically the same as that of Example 4, except that the oxalic acid solution in step 3 is replaced by a malonic acid solution, and the molar concentration of the malonic acid solution is 0.5 mol / L. Comparative Example 1 cannot form the second leaching residue.

[0100] Comparative Example 2

[0101] The preparation method is basically the same as that of Example 4, except that the oxalic acid solution in step 3 is replaced by oxalic acid powder. The amount of oxalic acid in the oxalic acid powder is the same as that in the oxalic acid solution in Example 4. Comparative Example 2 cannot form the second leaching residue.

[0102] Comparative Example 3

[0103] The preparation method is basically the same as that of Example 4, except that the oxalic acid solution in step 3 is replaced by malonic acid powder. The amount of oxalic acid in the malonic acid powder is the same as that in the oxalic acid solution in Example 4. Comparative Example 3 cannot form the second leaching residue.

[0104] Comparative Example 4

[0105] The preparation method of this comparative example is basically the same as that of Example 4, except that the low eutectic solvent in Example 4 is replaced by choline chloride-oxalic acid (ChCl-OA), choline chloride-succinic acid (ChCl-SA), choline chloride-glutaric acid (ChCl-GA), choline chloride-tartaric acid (ChCl-TA), and choline chloride-malic acid (ChCl-MA), respectively.

[0106] The obtained low eutectic solvent and waste NCM811 ternary lithium battery positive electrode material powder are added into a round-bottom flask, wherein the addition amount of NCM ternary lithium battery positive electrode material powder in the low eutectic solvent is 20 g / L, and the mixture is heated and stirred at 100°C in an oil bath for 45 min at a speed of 400 r / min to verify the selective leaching and separation performance of other low eutectic solvents on nickel and other metals in the ternary lithium battery positive electrode material powder. After the reaction, the leaching solution is obtained by filtration; the concentration of each metal ion in the leaching solution is determined by atomic absorption spectrometry.

[0107] Test results such as Fig.14 As shown by Fig.14 It can be seen that the choline chloride-malonic acid (ChCl-Mal) used in the embodiment of the present invention can achieve the separation of nickel and cobalt in the positive electrode material, while other types of low eutectic solvents cannot achieve the separation of nickel and cobalt in the positive electrode material.

[0108] From the above examples, it can be seen that the present invention provides a method for selectively separating valuable metals from waste ternary lithium battery positive electrode materials using a low eutectic solvent. In the traditional process, inorganic strong acids such as hydrochloric acid (HCl) and sulfuric acid (H 2 SO 4 ), nitric acid (HNO 3 ) and phosphoric acid (H 3 PO 4) as a leaching agent. These reagents show high leaching efficiency due to their strong acidity, but there are potential problems such as operational safety, secondary pollution, and equipment damage in the recovery process, thereby increasing the recovery cost and process complexity. The present invention solves the technical problems that the existing leaching methods of valuable metals in the positive electrode materials of waste ternary lithium batteries are high in cost, easy to produce intermediate pollution, and difficult to selectively separate transition metals. The present invention first prepares a low eutectic solvent, then performs selective leaching and separation of nickel and cobalt, then performs selective leaching and separation of cobalt and manganese, and finally performs manganese and lithium separation, four steps. The low eutectic solvent provided by the present invention has good thermal stability, and at the same time has a good separation effect on lithium, nickel, cobalt, and manganese in the positive electrode powder of waste ternary lithium batteries, so as to achieve green and low-cost tiered separation of the four valuable metals of lithium, nickel, cobalt, and manganese. The present invention optimizes the operating parameters in the method and separates the transition metals nickel and cobalt with similar chemical properties in the positive electrode powder for the first time in a mild environment and in a short time. Then, the separation of cobalt and manganese is completed by adding oxalic acid aqueous solution water to replace the expensive metal extractant. Finally, lithium is retained in the leachate and can be recovered by evaporation and crystallization.

[0109] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for selectively separating valuable metals from waste ternary lithium battery positive electrode materials, characterized in that: The following steps are involved: heating and mixing choline chloride, malonic acid and water to obtain a deep eutectic solvent; The low eutectic solvent and the waste ternary lithium battery positive electrode material are mixed to separate nickel, so as to obtain a first leaching residue and a first leaching solution; the first leaching residue contains nickel element; the waste ternary lithium battery positive electrode material is a nickel cobalt manganese oxide positive electrode material; The first leaching solution and the oxalic acid aqueous solution are mixed to separate cobalt, thereby obtaining a second leaching residue and a second leaching solution; the second leaching residue contains the cobalt element; The second leaching solution and an inorganic strong alkali solution are mixed to separate manganese, thereby obtaining a third leaching residue and a third leaching solution; the third leaching residue contains manganese elements, and the third leaching solution contains lithium elements.

2. The method according to claim 1, characterized in that The molar ratio of the choline chloride to malonic acid is 1:(0.5-2).

3. The method according to claim 1 or 2, characterized in that: The mass of the water accounts for 10-45% of the total mass of the choline chloride, malonic acid and water.

4. The method according to claim 1, characterized in that The temperature of the heating and mixing is 60-80° C., and the time is 30-120 min.

5. The method according to claim 1, characterized in that The ratio of the mass of the waste ternary lithium battery positive electrode material to the volume of the low eutectic solvent is (20-50) g:1L.

6. The method according to claim 1 or 5, characterized in that: The nickel separation temperature is 80-120° C., and the insulation time is 30-75 minutes.

7. The method according to claim 1, characterized in that The molar concentration of the oxalic acid aqueous solution is 0.2-3 mol / L; The volume ratio of the first leaching solution to the oxalic acid aqueous solution is 1:(0.5-4).

8. The method according to claim 1 or 7, characterized in that: The cobalt separation temperature is 60-100° C., and the insulation time is 30-120 minutes.

9. The method according to claim 1, characterized in that: The inorganic strong alkali solution is a sodium hydroxide solution, and the molar concentration of the inorganic strong alkali solution is 1-3 mol / L; the pH value of the manganese separation is ≥9.

10. The method according to claim 1 or 9, characterized in that: The pH value of the manganese separation is 9-12; the temperature is room temperature, and the time is 30-120 minutes.

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