Method for recovering valuable metal in waste lithium battery electrode plate

Abstract

The invention discloses a green recovery method for valuable metals in waste lithium battery electrode slices. The method comprises the following steps: mechanically crushing an electrode plate disassembled from a waste lithium battery into particles with the particle size of 1-5mm, and carrying out ultrasonic treatment separation on the obtained particles to obtain an aluminum foil and an active material; dissolving the compound extract of the radix scutellariae and the cortex phellodendri in deionized water to prepare a compound extracting solution of the radix scutellariae and the cortex phellodendri with the mass concentration of 10-30%; the method comprises the following steps: adding an active material and a compound extracting solution into a reaction container according to a solid-to-liquid ratio of 1g: (5-15) mL, and carrying out leaching reaction for 3-6 hours at the temperature of 30-60 DEG C and at the stirring speed of 200-500 r / min; and the reaction liquid is filtered, and leaching liquid and leaching residues are obtained. The method is easy to operate, low in cost, free of use of chemical reagents such as strong acid and strong alkali, capable of reducing secondary pollution, environmentally friendly and high in metal leaching rate and recovery rate.

Description

Technical Field

[0001] The present invention belongs to the technical field of resource recycling, and particularly relates to a green recovery method for valuable metals in waste lithium battery electrode sheets. Background Art

[0002] With the wide application of lithium-ion batteries in fields such as electronic devices and electric vehicles, the number of waste lithium batteries has increased sharply. Waste lithium batteries contain various valuable metals, such as cobalt, lithium, nickel, etc. If not effectively treated, it will not only cause waste of resources, but also cause serious environmental pollution.

[0003] Currently, the treatment methods for waste lithium batteries mainly include physical methods, chemical methods, and biological methods, etc. Physical methods usually include crushing, screening, etc., but their metal recovery rates are relatively low; chemical methods often require the use of chemical reagents such as strong acids and strong alkalis, which are prone to secondary pollution; although biological methods have the characteristics of environmental friendliness, their treatment efficiency is low. Therefore, developing an efficient, environmentally friendly, and low-cost treatment method for waste lithium batteries has important practical significance. Summary of the Invention

[0004] The primary object of the present invention is to provide a green recovery method for valuable metals in waste lithium battery electrode sheets, aiming to solve the problems of low metal recovery rate, serious secondary pollution, and low treatment efficiency existing in the prior art.

[0005] Another object of the present invention is to provide a compound extract of Scutellaria baicalensis and Phellodendron amurense for the above-mentioned recovery.

[0006] Another object of the present invention is to provide a preparation method of the above compound extract.

[0007] The present invention is realized as follows. A preparation method of a compound extract of Scutellaria baicalensis and Phellodendron amurense, the method comprising the following steps:

[0008] (1) Mix Scutellaria baicalensis powder and Phellodendron amurense powder evenly according to a mass ratio of 1 - 3:1 - 3, add them to an extraction container, add an ethanol aqueous solution with a volume fraction of 50% - 80% as an extraction solvent according to a material-liquid ratio of 1 g:10 - 20 / mL, and reflux and extract at 50 - 80°C for 2 - 4 hours. Filter the extract to obtain a primary extract and filter residue;

[0009] (2) Add an ethanol aqueous solution with a volume fraction of 50% - 80% to the filter residue again, with a material-liquid ratio of 1 g:8 - 15 mL, and reflux and extract at 40 - 70°C for 1 - 3 hours. Filter the extract to obtain a secondary extract;

[0010] (3) Combine the primary extract and the secondary extract, and concentrate the combined extract by vacuum distillation to remove ethanol and water to obtain a concentrated solution; subject the concentrated solution to vacuum drying to obtain a compound extract of Scutellaria baicalensis and Phellodendron amurense.

[0011] Preferably, in step (1), the mass ratio of Scutellaria baicalensis to Phellodendron amurense is 2:1.

[0012] Preferably, in step (1), the particle sizes of the Scutellaria baicalensis powder and the Phellodendron amurense powder are 0.5 - 2 mm.

[0013] Preferably, in step (3), the vacuum drying is carried out in a vacuum drying oven at 50 - 70 °C.

[0014] The present invention further discloses a compound extract of Scutellaria baicalensis and Phellodendron amurense prepared by the above method.

[0015] The present invention further discloses the application of the above compound extract in the recovery of valuable metals from waste lithium battery electrode sheets.

[0016] The present invention further discloses a method for recovering valuable metals from waste lithium battery electrode sheets, which method comprises the following steps:

[0017] (1) Mechanically crush the electrode sheets disassembled from waste lithium batteries into particles with a particle size of 1 - 5 mm, and separate the obtained particles by ultrasonic treatment to obtain aluminum foil and active materials; dissolve the above compound extract of Scutellaria baicalensis and Phellodendron amurense with deionized water to prepare a compound extraction solution of Scutellaria baicalensis and Phellodendron amurense with a mass concentration of 10% - 30%.

[0018] (2) Add the above active materials and the compound extraction solution to a reaction vessel according to a solid-liquid ratio of 1 g:5 - 15 mL, and carry out a leaching reaction at 30 - 60 °C and a stirring speed of 200 - 500 r / min for 3 - 6 hours.

[0019] (3) Filter the reaction solution to collect the leaching solution containing valuable metal ions including lithium, cobalt, nickel, and manganese.

[0020] Preferably, in step (2), during the leaching reaction, a leaching aid accounting for 1% - 5% of the volume of the compound extraction solution is added.

[0021] Preferably, the leaching aid is hydrogen peroxide with a mass fraction of 30%.

[0022] The present invention overcomes the deficiencies of the prior art and provides a method for recovering valuable metals from waste lithium battery electrode sheets. The technical solution adopted by the present invention is: after discharging and disassembling waste lithium batteries, anode sheets, cathode sheets, and diaphragms are obtained.

[0023] The anode sheet is mainly composed of copper foil and graphite powder, and the processing technology and process are quite mature. The processing process is usually as follows: First, physical disassembly is carried out. The battery is broken into small pieces by a shredder, and then the plastic separator is separated by air classification. Then, a magnetic separator is used to separate magnetic substances such as iron shells and nickel tapes. Then, a vibrating screen is used to separate the black powder (graphite) from the copper-aluminum debris. The black powder is directly collected, and the coarse particles are further ground and refined. Finally, the copper-aluminum mixture is separated by specific gravity separation or hydrometallurgy to finally obtain high-purity copper powder and aluminum powder.

[0024] The separator is mostly made of polyolefin materials (such as PP / PE). The processing process is as follows: The separator is preliminarily separated from the metal debris by air classification or cyclone separation technology, and the monomer raw materials are recovered by pyrolysis or solvent extraction.

[0025] The cathode sheet is composed of aluminum foil and active materials (such as lithium cobaltate, ternary lithium). First, the aluminum foil and the active materials are separated by mechanical crushing and ultrasonic treatment. The ultrasonic treatment process is also a mature process. Specifically, cathode sheet particles with a size of 1-5 mm are placed in a prepared container, and an appropriate amount of treatment liquid is added to ensure that the particles can be completely immersed in the treatment liquid. The ratio of particles to the treatment liquid can be adjusted according to the actual situation. Generally, a solid-liquid ratio of 1:5-1:10 (mass-volume ratio, g / mL) is more appropriate. The container containing the particles and the treatment liquid is placed in an ultrasonic device and ultrasonically treated at 30 °C for 10-60 minutes. The specific time depends on factors such as the nature of the particles, the types and degrees of surface contaminants, etc. For removing impurities such as dust and oil stains on the surface of the electrode sheet particles, a relatively low ultrasonic power (100-200 W) and a moderate frequency (30-40 kHz) usually can meet the requirements. For separating the aluminum foil and the active substances, higher ultrasonic energy is required, that is, a larger ultrasonic power (300-500 W) and an appropriate frequency (40-80 kHz). During the ultrasonic treatment process, the state of the particles and the changes in the treatment liquid can be observed regularly. If it is found that the particles have agglomeration phenomena or the treatment effect is uneven, stirring can be appropriately carried out to make the particles fully contact with the treatment liquid and improve the ultrasonic treatment effect. The stirring method can be manual stirring or using equipment such as a magnetic stirrer for stirring.

[0026] Then, the compound extraction solution of Scutellaria baicalensis and Phellodendron amurense of the present invention is used to selectively extract metals such as lithium and cobalt in the active materials, avoiding strong acid and strong base pollution. In the present invention, the leaching reaction of valuable metals in the active materials under the action of the compound extraction solution and hydrogen peroxide, the principle of this reaction is as follows:

[0027] Leaching reaction of lithium cobaltate (LiCoO2):

[0028] 2LiCoO2+H2O2+4H + =2Li + +2Co 2++O2↑ + 2H2O;

[0029] Leaching reaction of lithium nickelate (LiNiO2):

[0030] 2LiNiO2 + H2O2 + 4H + = 2Li + + 2Ni 2+ + O2↑ + 2H2O;

[0031] Leaching reaction of lithium manganate (LiMn2O4):

[0032] LiMn2O4 + H2O2 + 4H + = Li + + 2Mn 2+ + O2↑ + 2H2O.

[0033] Finally, valuable metal ions in the leachate are separated and recovered by conventional extraction and chemical precipitation methods. Among them, the extraction process of the extraction method is specifically as follows:

[0034] 1. Pretreatment: Filter the leachate to remove insoluble impurities, and adjust parameters such as the pH value and concentration of the leachate to meet the extraction requirements.

[0035] 2. Extraction: Add the prepared extractant and the pretreated leachate to the extraction equipment (such as an extraction tank or a centrifugal extractor) according to the set phase ratio, mix well, and carry out the extraction reaction.

[0036] 3. Static stratification: After the extraction is completed, let the mixed solution stand to fully stratify the organic phase and the aqueous phase.

[0037] 4. Separation: Use a liquid separation device to separate the organic phase and the aqueous phase to obtain the organic phase loaded with metal ions and the raffinate. The small amount of metal ions remaining in the raffinate can be further processed and recovered, and the organic phase enters the stripping process.

[0038] 5. Stripping:

[0039] (1) Lithium stripping: The organic phase loaded with lithium is stripped with a 0.5 - 1 mol / L sodium carbonate solution to transfer lithium ions from the organic phase to the aqueous phase. The stripping phase ratio is 2:1, the temperature is 25°C, and the time is 10 - 15 min.

[0040] (2) Cobalt and nickel stripping: The organic phase loaded with cobalt and nickel is stripped with a 2 - 3 mol / L hydrochloric acid solution. The stripping phase ratio is 1:1, the temperature is 25°C, and the time is 15 - 20 min.

[0041] (3) Manganese back-extraction: The manganese-loaded organic phase is back-extracted with a 1-2 mol / L sulfuric acid solution. The back-extraction phase ratio is 1:1, the temperature is 20-25 °C, and the time is 10-15 min.

[0042] 6. Extractant regeneration: After the back-extracted organic phase is washed and purified, it can be recycled to reduce production costs.

[0043] 7. Selection of extractant:

[0044] (1) Lithium element extraction

[0045] Extractant: Tributyl phosphate (TBP) is used in combination with a nitric acid system. TBP can form a stable complex with lithium ions to achieve selective extraction of lithium ions.

[0046] Principle: In a nitric acid medium, lithium ions combine with TBP through coordination bonds to form a hydrophobic complex and enter the organic phase.

[0047] Conditions: The nitric acid concentration is controlled at 2-3 mol / L, the TBP volume fraction is 20-30%, the extraction temperature is 25-30 °C, the phase ratio (organic phase: aqueous phase) is 1:1, and the extraction time is 10-15 min.

[0048] (2) Cobalt and nickel element extraction

[0049] Extractant: Di(2-ethylhexyl) phosphoric acid (P204). P204 has a strong complexing ability with cobalt and nickel ions and can separate cobalt and nickel from other metal ions under certain pH conditions.

[0050] Principle: The phosphoric acid group in the P204 molecule undergoes a cation exchange reaction with cobalt and nickel ions to form a stable chelate.

[0051] Conditions: Adjust the pH of the leaching solution to 3-4, the P204 volume fraction is 15-20%, sulfonated kerosene is used as a diluent, the phase ratio is 1:1-1:2, the extraction temperature is 25 °C, and the extraction time is 15-20 min. Through multi-stage countercurrent extraction, the extraction rate and separation effect of cobalt and nickel can be further improved.

[0052] (3) Manganese element extraction

[0053] Extractant: Methyl isobutyl ketone (MIBK) has good extraction performance for manganese ions in a perchloric acid medium.

[0054] Principle: In a perchloric acid environment, manganese ions form a coordination compound with MIBK to achieve the extraction and separation of manganese ions.

[0055] Conditions: perchloric acid concentration 4 - 5 mol / L, MIBK volume fraction 30 - 40%, phase ratio 1:1, extraction temperature 20 - 25 °C, extraction time 10 - 15 min.

[0056] In the present invention, the chemical precipitation method is used to purify the metal ion solution obtained by extraction. Taking lithium as an example, sodium carbonate solution is added to the solution containing lithium ions, and the pH is adjusted to 8 - 9 to precipitate lithium ions in the form of lithium carbonate. After filtration, washing, and drying of the precipitate, high-purity lithium carbonate products can be obtained by calcination at high temperature. For metals such as cobalt, nickel, and manganese, similar methods can also be used to obtain high-purity metal compounds by adding corresponding precipitating agents such as ammonium oxalate and sodium sulfide.

[0057] Compared with the disadvantages and deficiencies of the prior art, the present invention has the following beneficial effects:

[0058] (1) The present invention uses the Chinese herbal medicine extract to treat waste lithium batteries, avoiding the use of chemical reagents such as strong acids and strong alkalis, reducing secondary pollution, and being environmentally friendly;

[0059] (2) The active ingredients in the Chinese herbal medicine extract of the present invention can specifically react with the metal compounds in the positive electrode sheet, improving the leaching rate and recovery rate of metals;

[0060] (3) The method of the present invention is simple to operate, has a low cost, and is easy to realize industrial application. Specific embodiments

[0061] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the following further describes the present invention in detail with reference to embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0062] Example 1

[0063] (1) Mix the Scutellaria baicalensis powder with a particle size of 0.5 - 2 mm and the Phellodendron amurense powder with a particle size of 0.5 - 2 mm evenly according to a mass ratio of 1:3, add them to the extraction container, add an ethanol aqueous solution with a volume fraction of 50% as the extraction solvent according to a solid-liquid ratio of 1 g:10 mL, and reflux and extract at 80 °C for 4 hours. Filter the extract to obtain the primary extract and the filter residue;

[0064] (2) Add the ethanol aqueous solution with a volume fraction of 80% to the filter residue again, with a solid-liquid ratio of 1 g:15 mL, reflux and extract at 70 °C for 1 hour, and filter the extract to obtain the secondary extract;

[0065] (3) Combine the primary extract and the secondary extract, and concentrate the combined extract by vacuum distillation to remove ethanol and water, obtaining a concentrated solution; dry the concentrated solution in a vacuum drying oven at 50°C to obtain the compound extract (dry powder) of Scutellaria baicalensis and Phellodendron amurense.

[0066] Example 2

[0067] (1) Mix the Scutellaria baicalensis powder with a particle size of 0.5 - 2 mm and the Phellodendron amurense powder with a particle size of 0.5 - 2 mm evenly according to a mass ratio of 3:1, add them to an extraction container, add an ethanol aqueous solution with a volume fraction of 80% as the extraction solvent according to a material-liquid ratio of 1 g:0 / mL, reflux and extract at 50°C for 2 hours, filter the extract to obtain the primary extract and the filter residue;

[0068] (2) Add the ethanol aqueous solution with a volume fraction of 50% to the filter residue again, with a material-liquid ratio of 1 g:8 mL, reflux and extract at 40°C for 3 hours, filter the extract to obtain the secondary extract;

[0069] (3) Combine the primary extract and the secondary extract, and concentrate the combined extract by vacuum distillation to remove ethanol and water, obtaining a concentrated solution; dry the concentrated solution in a vacuum drying oven at 70°C to obtain the compound extract (dry powder) of Scutellaria baicalensis and Phellodendron amurense.

[0070] Example 3

[0071] (1) Mix the Scutellaria baicalensis powder with a particle size of 0.5 - 2 mm and the Phellodendron amurense powder with a particle size of 0.5 - 2 mm evenly according to a mass ratio of 2:1, add them to an extraction container, add an ethanol aqueous solution with a volume fraction of 65% as the extraction solvent according to a material-liquid ratio of 1 g:15 / mL, reflux and extract at 65°C for 3 hours, filter the extract to obtain the primary extract and the filter residue;

[0072] (2) Add the ethanol aqueous solution with a volume fraction of 65% to the filter residue again, with a material-liquid ratio of 1 g:12 mL, reflux and extract at 55°C for 1 - 3 hours, filter the extract to obtain the secondary extract;

[0073] (3) Combine the primary extract and the secondary extract, and concentrate the combined extract by vacuum distillation to remove ethanol and water, obtaining a concentrated solution; dry the concentrated solution in a vacuum drying oven at 60°C to obtain the compound extract (dry powder) of Scutellaria baicalensis and Phellodendron amurense.

[0074] Example 4

[0075] (1) The electrode sheets disassembled from waste lithium batteries are mechanically crushed into particles with a particle size of 1 - 5 mm. The obtained particles are ultrasonically treated and then aluminum foil and active materials are separated from the electrode sheet particles; the compound extract prepared in Example 3 is dissolved in deionized water to prepare a compound extract solution of Scutellaria baicalensis and Phellodendron amurense with a mass concentration of 10%.

[0076] In step (1), the ultrasonic treatment is specifically as follows: the cathode sheet particles are put into a prepared container, a treatment liquid is added and it is ensured that the particles can be completely immersed in the treatment liquid. The container is put into an ultrasonic device and ultrasonically treated at 30°C, 150 W, and 35 kHz for 30 minutes to remove impurities such as dust and oil on the surface of the electrode sheet particles, and then ultrasonically treated for another 1 h at 400 W, 60 kHz, and in a state of appropriate stirring.

[0077] (2) The above-mentioned active materials and the compound extract solution are added to a reaction container according to a solid-liquid ratio of 1 g:15 mL, and leaching reaction is carried out at 60°C and a stirring speed of 200 r / min for 3 hours.

[0078] (3) The reaction solution after the reaction in step (2) is filtered to obtain leaching solution 1 and leaching residue.

[0079] Example 5

[0080] (1) The electrode sheets disassembled from waste lithium batteries are mechanically crushed into particles with a particle size of 1 - 5 mm. The obtained particles are ultrasonically treated to separate aluminum foil and active materials; the compound extract prepared in Example 3 is dissolved in deionized water to prepare a compound extract solution of Scutellaria baicalensis and Phellodendron amurense with a mass concentration of 30%; the ultrasonic treatment here is the same as that described in Example 4.

[0081] (2) The above-mentioned active materials and the compound extract solution are added to a reaction container according to a solid-liquid ratio of 1 g:5 mL, and leaching reaction is carried out at 30°C and a stirring speed of 500 r / min for 6 hours. During the leaching reaction, hydrogen peroxide with a volume of 1% of the compound extract solution and a mass fraction of 30% is added.

[0082] (3) The reaction solution after the reaction in step (2) is filtered to obtain leaching solution 2 and leaching residue.

[0083] Example 6

[0084] (1) The electrode sheets disassembled from waste lithium batteries are mechanically crushed into particles with a particle size of 1 - 5 mm. The obtained particles are ultrasonically treated to separate aluminum foil and active materials; the compound extract prepared in Example 3 is dissolved in deionized water to prepare a compound extract solution of Scutellaria baicalensis and Phellodendron amurense with a mass concentration of 20%; the ultrasonic treatment here is the same as that described in Example 4.

[0085] (2) Add the above active material and compound extract into the reaction vessel at a solid-liquid ratio of 1 g: 10 mL, and carry out the leaching reaction for 4 hours at 45 °C and a stirring speed of 350 r / min. During the leaching reaction, hydrogen peroxide with a volume of 3% of the compound extract and a mass fraction of 30% is added.

[0086] (3) Filter the reaction solution after the reaction in step (2) to obtain the leaching solution 3 and the leaching residue.

[0087] Effect example

[0088] The valuable metal ions contained in the leaching solutions 1-3 prepared in Examples 4-6 are directly related to the type or model of the waste lithium batteries. For different types or models of waste lithium batteries, the composition and ratio of their electrode materials are different, resulting in differences in the content and types of various valuable metal ions in the leaching solution. The following are some common commercially available lithium battery product models and their corresponding metal composition characteristics:

[0089] 1. Lithium batteries for consumer electronics: Such as the common 18650 lithium battery, which is widely used in devices such as laptops and mobile power supplies. The cathode material of this type of battery often uses lithium cobaltate, so the content of cobalt and lithium ions in the leaching solution is relatively high.

[0090] 2. Lithium batteries for electric vehicles: For example, the 21700 lithium battery used in Tesla Model 3, whose cathode material is mostly ternary lithium battery (such as lithium nickel cobalt manganate or lithium nickel cobalt aluminate). In this case, in addition to lithium and cobalt ions, the content of nickel and manganese ions in the leaching solution is also considerable.

[0091] 3. Lithium batteries for energy storage: Some large-scale energy storage systems often use lithium iron phosphate square batteries, such as the energy storage battery of BYD. The leaching solution mainly contains metal ions such as lithium and iron, and the content of metal ions such as cobalt, nickel, and manganese is low or even absent, because these metal elements are not contained in the lithium iron phosphate electrode material.

[0092] To verify the recovery rates of lithium, cobalt, nickel, and manganese in the present invention, in this effect example, the leaching solutions 1-3 prepared in Examples 4-6 are selected for further recovery of lithium, cobalt, nickel, and manganese metals, including extraction by conventional extraction methods and purification of the obtained metal ion solutions by chemical precipitation methods.

[0093] In this effect example, the extraction process flow of the extraction method is specifically as follows:

[0094] 1. Pretreatment: Filter the leaching solution to remove insoluble impurities, and adjust parameters such as the pH value and concentration of the leaching solution to meet the extraction requirements.

[0095] 2. Extraction: The prepared extractant and the pretreated leaching solution are added to an extraction device (such as an extraction tank or a centrifugal extractor) according to a set phase ratio, and are fully mixed to carry out an extraction reaction.

[0096] 3. Static settling and separation: After the extraction is completed, the mixed solution is allowed to stand still to fully separate the organic phase and the aqueous phase.

[0097] 4. Separation: The organic phase and the aqueous phase are separated using a liquid separation device to obtain the organic phase loaded with metal ions and the raffinate. A small amount of metal ions remaining in the raffinate can be further processed and recovered, and the organic phase enters the stripping process.

[0098] 5. Stripping:

[0099] (1) Lithium stripping: The organic phase loaded with lithium is stripped with a 0.5 - 1 mol / L sodium carbonate solution, so that lithium ions are transferred from the organic phase to the aqueous phase. The stripping phase ratio is 2:1, the temperature is 25°C, and the time is 10 - 15 min.

[0100] (2) Cobalt and nickel stripping: The organic phase loaded with cobalt and nickel is stripped with a 2 - 3 mol / L hydrochloric acid solution. The stripping phase ratio is 1:1, the temperature is 25°C, and the time is 15 - 20 min.

[0101] (3) Manganese stripping: The organic phase loaded with manganese is stripped with a 1 - 2 mol / L sulfuric acid solution. The stripping phase ratio is 1:1, the temperature is 20 - 25°C, and the time is 10 - 15 min.

[0102] 6. Extractant regeneration: After the organic phase after stripping is washed, decontaminated, etc., it can be recycled to reduce production costs.

[0103] 7. Selection of extractant:

[0104] (1) Extraction of lithium element

[0105] Extractant: Tributyl phosphate (TBP) is used in combination with a nitric acid system. TBP can form a stable complex with lithium ions to achieve selective extraction of lithium ions.

[0106] Principle: In a nitric acid medium, lithium ions combine with TBP through coordination bonds to form a hydrophobic complex and enter the organic phase.

[0107] Conditions: The nitric acid concentration is controlled at 2 - 3 mol / L, the volume fraction of TBP is 20 - 30%, the extraction temperature is 25 - 30°C, the phase ratio (organic phase: aqueous phase) is 1:1, and the extraction time is 10 - 15 min.

[0108] (2) Extraction of cobalt and nickel elements

[0109] Extractant: Di(2-ethylhexyl) phosphoric acid (P204). P204 has a strong complexing ability for cobalt and nickel ions and can separate cobalt and nickel from other metal ions under certain pH conditions.

[0110] Principle: The phosphate group in the P204 molecule undergoes a cation exchange reaction with cobalt and nickel ions to form a stable chelate.

[0111] Conditions: Adjust the pH of the leaching solution to 3 - 4, the volume fraction of P204 is 15 - 20%, using sulfonated kerosene as the diluent, the phase ratio is 1:1 - 1:2, the extraction temperature is 25 °C, and the extraction time is 15 - 20 min. Through multi-stage countercurrent extraction, the extraction rate and separation effect of cobalt and nickel can be further improved.

[0112] (3) Extraction of manganese element

[0113] Extractant: Methyl isobutyl ketone (MIBK) has good extraction performance for manganese ions in perchloric acid medium.

[0114] Principle: In a perchloric acid environment, manganese ions form a coordination compound with MIBK to achieve the extraction and separation of manganese ions.

[0115] Conditions: The concentration of perchloric acid is 4 - 5 mol / L, the volume fraction of MIBK is 30 - 40%, the phase ratio is 1:1, the extraction temperature is 20 - 25 °C, and the extraction time is 10 - 15 min.

[0116] In this example of the effect, the chemical precipitation method is used to purify the metal ion solution obtained by extraction. Taking lithium as an example, sodium carbonate solution is added to the solution containing lithium ions, and the pH is adjusted to 8 - 9 to precipitate lithium ions in the form of lithium carbonate. After the precipitate is filtered, washed, and dried, it is calcined at high temperature to obtain a high-purity lithium carbonate product. For metals such as cobalt, nickel, and manganese, a similar method can also be used. By adding corresponding precipitating agents, such as ammonium oxalate, sodium sulfide, etc., high-purity metal compounds can be obtained.

[0117] Different types of waste lithium batteries are recycled and the recovery rates are counted. The results are shown in Table 1 below:

[0118] Table 1 Statistical results of recovery rates

[0119] Number Type of used lithium battery Lithium recovery rate Nickel recovery rate Cobalt recovery rate Manganese recovery rate Leaching solution 1 Tesla NCA battery (21700 type) 96％ 97％ 98％ 88％ Leaching solution 2 CATL NCM523 battery 93％ 95％ 96％ 86％ Leaching solution 3 CATL NCM523 battery 90％ 93％ 96％ 84％

[0120] In Table 1, for the CATL NCM523 battery (used in electric vehicles):

[0121] Active material: Li(Ni 0.5 Co 0.2 Mn 0.3 )O2, cobalt content 10.5%, nickel content 23.5%;

[0122] Battery mass: 50 kg / package, active material 30 kg, aluminum foil 6 kg, copper foil 5 kg;

[0123] Tesla NCA battery (21700 type):

[0124] Active material: Li(Ni 0.8 Co 0.15 Al 0.05 )O2, cobalt content 7.2%, nickel content 34%;

[0125] Battery mass: 45 kg / package, active material 28 kg, aluminum foil 5 kg, copper foil 4 kg.

[0126] In addition, in the embodiments of the present invention, for high-nickel models (such as NCM811), the concentration of baicalin in the compound extract of Scutellaria baicalensis and Phellodendron amurense can be increased (≥25 g / L) to enhance the complexing ability with Ni 2+ .

[0127] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a compound extract of Scutellaria baicalensis and Phellodendron amurense, characterized in that The method includes the following steps: (1) Mix Scutellaria baicalensis powder and Phellodendron amurense powder evenly at a mass ratio of 1-3:1-3, add them to an extraction container, add an ethanol aqueous solution with a volume fraction of 50%-80% as an extraction solvent according to a solid-liquid ratio of 1 g:10-20 mL, and reflux and extract at 50-80 °C for 2-4 hours. Filter the extract to obtain a primary extract and filter residue; (2) Add an ethanol aqueous solution with a volume fraction of 50%-80% to the filter residue again, with a solid-liquid ratio of 1 g:8-15 mL, and reflux and extract at 40-70 °C for 1-3 hours. Filter the extract to obtain a secondary extract; (3) Combine the primary extract and the secondary extract, concentrate the combined extract by vacuum distillation to remove ethanol and water to obtain a concentrated solution; vacuum dry the concentrated solution to obtain a compound extract of Scutellaria baicalensis and Phellodendron amurense.

2. The method according to claim 1, wherein In step (1), the mass ratio of Scutellaria baicalensis to Phellodendron amurense is 2:

1.

3. The method according to claim 1, wherein In step (1), the particle size of the Scutellaria baicalensis powder and Phellodendron amurense powder is 0.5-2 mm.

4. The method according to claim 1, wherein In step (3), the vacuum drying is carried out in a vacuum drying oven at 50-70 °C.

5. A compound extract of Scutellaria baicalensis and Phellodendron amurense prepared by the method according to any one of claims 1-4.

6. Use of the compound extract according to claim 5 in the recovery of valuable metals from waste lithium battery electrode sheets.

7. A method for recovering valuable metals from waste lithium battery electrode sheets, characterized in that, The method includes the following steps: (1) Mechanically crush the electrode sheets disassembled from waste lithium batteries into particles with a particle size of 1-5 mm, and separate the obtained particles by ultrasonic treatment to obtain aluminum foil and active materials; dissolve the compound extract according to claim 5 with deionized water to prepare a compound extract solution of Scutellaria baicalensis and Phellodendron amurense with a mass concentration of 10%-30%; (2) Add the above-mentioned active materials and the compound extract solution to a reaction container according to a solid-liquid ratio of 1 g:5-15 mL, and carry out a leaching reaction at 30-60 °C and a stirring speed of 200-500 r / min for 3-6 hours; (3) Filter the reaction solution to collect a leaching solution containing valuable metal ions including lithium, cobalt, nickel, and manganese.

8. The method according to claim 7, wherein In step (2), during the leaching reaction, a leaching aid with a volume of 1%-5% of the compound extract solution is added.

9. The method according to claim 8, wherein The leaching aid is hydrogen peroxide with a mass fraction of 30%.