Method for recovering nickel, cobalt, manganese, lithium, and negative electrode graphite from ternary lithium battery by means of high-pressure reduction

Abstract

A method for recovering nickel, cobalt, manganese, lithium, and negative electrode graphite from a ternary lithium battery by means of high-pressure reduction, comprising the following steps: carrying out low-acid leaching on waste battery powder, mixing low-acid leaching residues obtained after solid-liquid separation with an alkaline solution to make a slurry, carrying out high-pressure leaching on roasting residues obtained after primary roasting of the slurry, and carrying out secondary roasting on high-pressure leaching residues obtained after solid-liquid separation, thereby obtaining battery-grade graphite powder.

Description

A method for recovering nickel, cobalt, manganese, lithium and negative electrode graphite from ternary lithium batteries through high-voltage reduction Technical Field

[0001] The present disclosure belongs to the technical field of valuable metal resource regeneration, and specifically relates to a method for recovering nickel, cobalt, manganese, lithium and negative electrode graphite through high-voltage reduction of a ternary lithium battery. Background Art

[0002] In recent years, the rapid development of the new energy vehicle industry has also generated a large amount of solid waste—used lithium-ion batteries. Used lithium-ion batteries typically contain large amounts of hazardous organic pollutants and heavy metal inorganic compounds. Improper disposal can pose a serious threat to human health, the environment, and biota. The heavy metals and negative electrode graphite in used batteries have recycling value, as they can be reused in the manufacture of new energy materials, thereby reducing environmental pollution and generating positive economic benefits. Used ternary lithium-ion batteries contain large amounts of valuable metals such as nickel, cobalt, manganese, and lithium, and their recycling is beneficial to environmental protection and improving economic efficiency. In addition, the continuous decline in natural graphite resources and the rapid increase in the price of artificial graphite have made the effective recovery of negative electrode graphite from used batteries even more important. Therefore, high-efficiency and high-recovery waste battery recycling technologies have become a hot topic in recent years.

[0003] Currently, the main industrial process for recovering valuable metals from used batteries involves using sulfuric acid and hydrogen peroxide at atmospheric pressure to recover nickel, cobalt, manganese, and lithium from battery powder as nickel sulfate, cobalt sulfate, manganese sulfate, and lithium sulfate, respectively. This conventional method suffers from low recovery efficiency and can cause bubbling during the addition of hydrogen peroxide, increasing safety risks during on-site operations. An alternative approach utilizes a low-acid, high-pressure leaching process. However, this method fails to address two safety hazards. First, battery powder inevitably contains fluorine-containing compounds. These fluorine-containing compounds originate from lithium hexafluorophosphate in the electrolyte or PVDF in the separator. During the high-pressure acid leaching process, fluorine reacts with hydrogen ions to form hydrofluoric acid. Hydrofluoric acid is a highly corrosive acid that can corrode the autoclave, posing a safety hazard and increasing subsequent maintenance costs. Second, battery powder also contains materials such as aluminum foil. If these elemental metals are not treated prior to high-pressure leaching, they react with the acid during leaching to generate hydrogen gas, posing an explosion risk. Furthermore, if the leached residue containing carbon powder is directly discarded without recovering the negative electrode carbon powder, it will not only waste graphite resources but also have environmental and health impacts. Therefore, there is an urgent need to develop a method for efficiently recovering the valuable metals and negative electrode graphite from spent ternary lithium batteries.

[0004] Summary of the Invention

[0005] The present disclosure aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present disclosure proposes a method for recovering nickel, cobalt, manganese, lithium and negative electrode graphite from a ternary lithium battery through high-voltage reduction.

[0006] According to a first aspect of the present disclosure, a method for recovering nickel, cobalt, manganese, lithium and negative electrode graphite by high-voltage reduction of a ternary lithium battery is proposed, comprising the following steps:

[0007] S1: mixing waste battery powder with a first acid solution for leaching, and obtaining a first acid leaching solution and a first acid leaching residue after solid-liquid separation;

[0008] S2: mixing the first acid leaching residue obtained in step S1 with alkaline solution to prepare pulp, and roasting the pulp once to obtain roasted residue;

[0009] S3: mixing the roasted residue obtained in step S2 with a second acid solution, leaching under pressure, and obtaining a second acid leaching solution and a second acid leaching residue after solid-liquid separation, and performing secondary roasting on the second acid leaching residue to obtain battery-grade graphite powder;

[0010] Wherein, in step S1, the concentration of the first acid solution is 80-220 g / L, and the liquid-solid ratio of the first acid solution to the waste battery powder is (4-10): 1 mL / g;

[0011] In step S2, the pulping temperature is 70-100°C;

[0012] In step S3, the concentration of the second acid solution is 230-500 g / L, and the pressure of the pressurized leaching is 0.4-1.6 MPa.

[0013] In some embodiments, in step S1, the waste battery powder is obtained by discharging, disassembling and crushing waste ternary lithium batteries.

[0014] In some embodiments, in step S1, the liquid-to-solid ratio of the first acid solution to the waste battery powder is (5-8): 1 mL / g; and / or, the stirring speed during the leaching process is 300-500 rpm.

[0015] In some embodiments, in step S1, the first acid solution is a sulfuric acid solution, and the concentration of the first acid solution is 100-200 g / L. Lithium in the battery powder is leached prior to nickel, cobalt, and manganese. At this concentration, the first acid solution ensures efficient and complete leaching of lithium, avoiding any impact on the subsequent defluorination process.

[0016] In some embodiments, in step S1, the amount of the first acid solution added is in excess of the lithium content in the waste battery powder.

[0017] In some embodiments, in step S1, the leaching is performed under normal pressure.

[0018] In some embodiments, in step S1, the leaching time is 3-7 hours; and / or the pH value during the leaching process is controlled at 1.0-1.5; and / or the leaching temperature is 60-90° C. After the first acid leaching solution undergoes conventional purification, extraction, and other treatments, a metal liquid for preparing a ternary precursor is obtained.

[0019] In some embodiments, in step S2, the alkaline solution is at least one of a sodium hydroxide solution or a potassium hydroxide solution.

[0020] In some embodiments, in step S2, the alkali solution is a potassium hydroxide solution. Compared to sodium hydroxide, potassium hydroxide is less corrosive to some equipment. In addition, in the subsequent defluorination process, the solubility of potassium fluoride is much greater than that of sodium fluoride: 142g of potassium fluoride at 60°C, while 4.7g of sodium fluoride at 60°C. Using potassium hydroxide to form potassium fluoride, which is easily soluble in water, facilitates the removal of fluorine.

[0021] In some embodiments, in step S2, the concentration of the alkali solution is 1-3 mol / L; and / or the liquid-to-solid ratio of the alkali solution to the first acid leaching residue is (1-4): 1 mL / g.

[0022] In some embodiments, in step S2, the stirring speed during the slurrying is 300-500 rpm; and / or the slurrying time is 2-4 hours.

[0023] In some embodiments, in step S2, the primary roasting is performed in an air atmosphere; and / or the primary roasting temperature is 600-1000°C; and the primary roasting duration is 0.5-2 hours. The slurry contains a potassium hydroxide solution, which promotes the carbon powder to reduce the difficult-to-leach high-valent cobalt and manganese in the first acid leaching residue to easily leached low-valent metal oxides during roasting. The potassium hydroxide solution also reacts with fluorine-containing compounds in the first acid leaching residue, thereby removing them.

[0024] The slurry is thoroughly mixed before the primary roasting process. During the roasting process, the carbon powder reacts preferentially with the metal oxides. Furthermore, because the primary roasting atmosphere is air, the carbon powder does not reduce the metal elements to their elemental form. This prevents the metal element from reacting with the acid to generate hydrogen during subsequent high-pressure leaching, which could create an explosion risk. The roasting time should be limited to a minimum, as this will cause the carbon powder to react with oxygen in the air, resulting in significant losses.

[0025] In some embodiments, step S2 further includes washing the calcined slag with water at a liquid-to-solid ratio of (2-5):1 mL / g; and / or, washing for 1-3 hours; and / or, washing at a temperature of 60-90°C.

[0026] In some embodiments, in step S3, the second acid solution is a sulfuric acid solution, and the concentration of the second acid solution is 250-450 g / L.

[0027] In some embodiments, in step S3, the liquid-to-solid ratio of the second acid solution to the calcined slag is (1-3): 1 mL / g.

[0028] In some embodiments, in step S3, the pressure leaching time is 3-8 hours; and / or the pressure leaching temperature is 110-200°C. Pressurization increases the boiling point of water, thereby raising the pressure leaching temperature. High temperatures can effectively improve leaching efficiency and also allow the leaching of high-valent nickel and cobalt that may be present in the roasted slag.

[0029] In some embodiments, in step S3, the secondary calcination is performed in an inert atmosphere; and / or the secondary calcination temperature is 2000-3000° C.; and / or the secondary calcination time is 20-40 hours. The secondary calcination converts the amorphous carbon material into a graphitized carbon material, thereby improving the recovery rate of the graphite.

[0030] In some embodiments, during the leaching process in step S1 and the pressurized leaching process in step S3, the stirring speed is independently 300-500 rpm.

[0031] According to the second aspect of the present disclosure, a method for recycling lithium batteries is proposed, comprising the steps of the method for recovering nickel, cobalt, manganese, lithium and negative electrode graphite by high-voltage reduction of ternary lithium batteries as described in the first aspect of the present disclosure.

[0032] According to the third aspect of the present disclosure, the application of the method for recovering nickel, cobalt, manganese, lithium and negative electrode graphite by high-voltage reduction of ternary lithium batteries described in the first aspect of the present disclosure in lithium battery recycling is proposed.

[0033] According to one embodiment of the present disclosure, there are at least the following beneficial effects:

[0034] 1. The present disclosure provides a method for recovering nickel, cobalt, manganese, lithium and negative electrode graphite from waste ternary lithium batteries through high-pressure reduction. The first step of the method is low-acid selective lithium extraction. By controlling the amount of acid, all the lithium in the raw material and a small amount of nickel, cobalt and manganese are leached. The leaching of part of the nickel, cobalt and manganese can reduce the burden of subsequent high-pressure leaching. In addition, since the aluminum surface in the waste battery powder is often covered with a layer of aluminum oxide, the aluminum oxide will not be dissolved under the conditions of low-acid leaching. In the subsequent high-pressure leaching process, the boiling point of water can be increased by pressurization, thereby increasing the leaching temperature. With the use of a higher concentration of acid solution, the complete leaching of nickel, cobalt and manganese can be ensured. The use of a higher concentration of acid solution in high-pressure leaching is also beneficial for reducing the amount of new acid solution added when it is subsequently reused for low-acid leaching.

[0035] 2. In the second step of the present disclosure, potassium hydroxide solution is added to prepare the slurry. During the high-temperature roasting of the slurry, the fluorine-containing compound reacts with potassium hydroxide to form potassium fluoride, which is easily soluble in water. If lithium is present, lithium fluoride will preferentially form. Lithium fluoride is insoluble in water, while potassium fluoride is easily soluble in water. The solubility of potassium fluoride is much greater than that of lithium fluoride. The presence of lithium in the defluorination process makes it difficult to completely remove the fluorine. Therefore, the first step of low-acid selective lithium extraction is necessary to avoid the formation of hydrogen fluoride in the subsequent high-pressure leaching process, which may cause corrosion and damage to the autoclave.

[0036] 3. The present invention pulps and roasts the first acid leaching residue with potassium hydroxide solution, which has the following four main effects:

[0037] (1) The first acid leaching residue is stirred and reacted with potassium hydroxide solution at high temperature to remove aluminum / alumina from waste battery powder. Elemental aluminum / alumina reacts with potassium hydroxide to form potassium aluminate soluble in water. The first function is to avoid the reaction of elemental aluminum with acid to generate hydrogen during high-pressure leaching, which may cause explosion risk. The second function is to reduce the subsequent impurity removal load, such as the removal of iron, aluminum and other impurities. The reaction equation is as follows: 2Al+2KOH+2H2O→2KAlO2+3H2 Al2O3+2KOH+2H2O→2KAlO2+3H2O

[0038] (2) The first acid leaching residue is stirred and reacted with potassium hydroxide solution at high temperature. Fluorine-containing compounds can react with potassium hydroxide solution to generate potassium fluoride which is easily soluble in water. Potassium fluoride in the residue can be completely removed by water washing. Fluorine-containing compounds include PVDF (chemical formula C2H2F2) in the diaphragm and hydrogen fluoride residual in low acid leaching. The reaction equation is as follows: C2H2F2(PVDF)+2KOH+O2→2KF+CO2+2H2O HF+KOH→KF+H2O

[0039] (3) The high-valent metals in the first acid leaching residue are converted into low-valent metal oxides that are easy to leach under the reduction effect of carbon powder, reducing the input cost of reducing agent auxiliary materials. Potassium hydroxide plays a catalytic role, which is conducive to the reduction reaction. The catalytic mechanism is as follows: 2KOH+C→K2O+CO+H2 K2O+H2O→2KOH

[0040] Among them, the Ni ions in the reactants are in a valence state of +2, the Co ions are in a valence state of +3, and the Mn ions are in a valence state of +4; the Ni, Co, and Mn ions in the products are all in a valence state of +2.

[0041] (4) Calcination: Oxidize the unreacted metal elements in the first acid leaching residue into metal oxides to avoid the generation of hydrogen in the high-pressure reactor, which may easily cause explosion risks. The relevant reaction equations are as follows: 2Al+3H2SO4→Al2(SO4)3+3H2↑ 4Al+3O2→2Al2O3 Al2O3+3H2SO4→Al2(SO4)3+3H2O

[0042] 4. The metal residue in the second leaching residue of the present invention is extremely low. Graphitized carbon material can be obtained by high-temperature roasting under inert gas, which can be used as battery-grade graphite. This solves the problem of difficulty in graphite recovery in battery powder leaching residue and achieves effective recycling of graphite.

[0043] 5. The present invention has the advantages of simple process, environmental friendliness, high safety, high economic benefit, high production efficiency and high recycling rate, which not only realizes the resource utilization of waste batteries, but also improves economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The present disclosure is further described below with reference to the accompanying drawings and embodiments, wherein:

[0045] FIG1 is a process flow chart of Example 1 of the present disclosure. DETAILED DESCRIPTION

[0046] The following will clearly and completely describe the concept and technical effects of the present disclosure in conjunction with embodiments to fully understand the purpose, features and effects of the present disclosure.

[0047] Example 1

[0048] A method for recovering nickel, cobalt, manganese, lithium and negative electrode graphite from waste ternary lithium batteries by high-voltage reduction, as shown in FIG1 , comprises the following steps:

[0049] 1. Take 1 kg of waste battery powder, in which the nickel, cobalt, manganese and lithium contents are 26.2931%, 4.0768%, 3.5236% and 4.0665% respectively, add 5 L of water at a liquid-solid ratio of 5:1 mL / g, and then add 600 g of 98% sulfuric acid. The temperature is controlled at 70 ° C and the stirring speed is 350 rpm. The pH is maintained below 1.1 during the reaction. After reacting for 6 hours, the low-acid leachate and low-acid leach residue are obtained by filtration. The low-acid leachate is used for the preparation of the ternary precursor after the impurity removal process.

[0050] 2. Add 1 mol / L potassium hydroxide solution to the low-acid leaching residue at a liquid-solid ratio of 1:3 mL / g to form a slurry, stir at 85°C for 3 hours to mix, put the mixed slurry into a roasting furnace at a temperature of 900°C and a roasting time of 1.5 hours. After the roasting is completed, the roasted slag is washed with 80°C pure water for 2 hours, filtered and then rinsed with pure water to obtain a roasted washed slag.

[0051] 3. The roasted washing slag F content is 0.0001wt.%, and 1.5L of water is added at a liquid-solid ratio of 3:1mL / g and placed in a high-pressure reactor. Then 500g of 98% sulfuric acid is added. The temperature is controlled at 160°C and the pressure is 0.8Mpa. After reacting for 3h, the autoclave temperature is cooled, and the high-pressure leaching liquid obtained by filtration is returned to the low-acid leaching as the acid solution. The obtained high-pressure leaching slag is washed and graphitized at 2000°C for 30h to obtain battery-grade graphite for sale.

[0052] The leaching results are as follows:

[0053] Among them, the recovery rates of Ni, CO, Mn and Li are obtained by the following steps: measuring the mass of the battery powder raw material and the content of Ni, Co, Mn and Li therein, and the mass of the high-pressure leaching residue and the content of Ni, Co, Mn and Li therein, and calculating the mass of Ni, Co, Mn and Li in the battery powder raw material and the high-pressure leaching residue respectively. The ratio of the difference between the two and the mass of the corresponding metal in the battery powder raw material is the recovery rate of the metal element.

[0054] The recovery rate of C is obtained by the following steps: using a carbon-sulfur analyzer to respectively determine the C content in the battery powder raw material and the high-pressure leaching residue after graphitization treatment, and calculating the mass of C therein based on the mass of the battery powder raw material and the high-pressure leaching residue after graphitization treatment. The ratio of the mass of C in the high-pressure leaching residue after graphitization treatment to the mass of C in the battery powder raw material is the C recovery rate.

[0055] A method for recycling lithium batteries, comprising the steps of the above-mentioned method for high-voltage reduction of ternary lithium batteries to recover nickel, cobalt, manganese, lithium and negative electrode graphite.

[0056] Example 2

[0057] A method for recovering nickel, cobalt, manganese, lithium and negative electrode graphite from waste ternary lithium batteries through high-voltage reduction, comprising the following steps:

[0058] 1. Take 1 kg of waste battery powder, in which the nickel, cobalt, manganese and lithium contents are 25.6394%, 6.0311%, 4.5143% and 5.6091% respectively, add 6 L of water at a liquid-solid ratio of 6:1 mL / g, and then add 700 g of 98% sulfuric acid. The temperature is controlled at 90 ° C and the stirring speed is 300 rpm. The pH is maintained below 1.2 during the reaction. After reacting for 5 hours, the low-acid leachate and low-acid leach residue are obtained by filtration. The low-acid leachate is used for the preparation of the ternary precursor after the impurity removal process.

[0059] 2. Add 3 mol / L potassium hydroxide solution to the low-acid leaching residue at a liquid-solid ratio of 1:2 mL / g to form a slurry, stir at 80°C for 3 hours to mix, put the mixed slurry into a roasting furnace at a temperature of 900°C and a roasting time of 1.5 hours. After the roasting is completed, the roasted slag is washed with 80°C pure water for 2 hours, filtered and then rinsed with pure water to obtain a roasted washed slag.

[0060] 3. The roasted washing slag F content is 0.0002wt.% and 1L of water is added at a liquid-solid ratio of 2:1mL / g and placed in a high-pressure reactor. Then 400g of 98% sulfuric acid is added. The temperature is controlled at 180°C and the pressure is 1Mpa. After the reaction for 4 hours, the autoclave temperature is cooled, and the high-pressure leaching liquid obtained by filtration is returned to the low-acid leaching as the acid solution. The obtained high-pressure leaching slag is washed and graphitized at 2500°C for 25 hours to obtain battery-grade graphite for sale.

[0061] The leaching results are as follows:

[0062] A method for recycling lithium batteries, comprising the steps of the above-mentioned method for high-voltage reduction of ternary lithium batteries to recover nickel, cobalt, manganese, lithium and negative electrode graphite.

[0063] Example 3

[0064] A method for recovering nickel, cobalt, manganese, lithium and negative electrode graphite from waste ternary lithium batteries through high-voltage reduction, comprising the following steps:

[0065] 1. Take 1 kg of waste battery powder, in which the nickel, cobalt, manganese and lithium contents are 28.0455%, 5.0033%, 3.9018% and 7.9602% respectively, add 7 L of water at a liquid-solid ratio of 7:1 mL / g, and then add 900 g of 98% sulfuric acid. The temperature is controlled at 60 ° C and the stirring speed is 400 rpm. The pH is maintained at 1.0 during the reaction. After reacting for 5.5 hours, the low-acid leachate and low-acid leach residue are obtained by filtration. The low-acid leachate is used for the preparation of the ternary precursor after the impurity removal process.

[0066] 2. Add 2 mol / L potassium hydroxide solution to the low-acid leaching residue at a liquid-solid ratio of 1:1 mL / g to form a slurry, stir at 70°C for 2 hours, and put the mixed slurry into a roasting furnace at a temperature of 1000°C for 1 hour. After the roasting is completed, the roasted slag is washed with 70°C pure water for 3 hours, filtered, and then rinsed with pure water to obtain a roasted washed slag.

[0067] 3. The roasted washed slag F content is 0.0001wt.%, and 600mL of water is added at a liquid-solid ratio of 1:1mL / g and placed in a high-pressure reactor. Then 250g of 98% sulfuric acid is added, the temperature is controlled at 170°C, the pressure is 0.9Mpa, and the reaction is carried out for 6 hours. The high-pressure leaching liquid obtained by filtration is returned to the low-acid leaching as the acid solution. The obtained high-pressure leaching slag is washed and graphitized at 3000°C for 20 hours to obtain battery-grade graphite for sale.

[0068] The leaching results are as follows:

[0069] A method for recycling lithium batteries, comprising the steps of the above-mentioned method for high-voltage reduction of ternary lithium batteries to recover nickel, cobalt, manganese, lithium and negative electrode graphite.

[0070] Comparative Example 1

[0071] A method for recovering nickel, cobalt, manganese, lithium and negative electrode graphite from waste ternary lithium batteries by high-voltage reduction, which differs from Example 1 in that the low-acid leaching residue is not treated with a potassium hydroxide solution, comprises the following steps:

[0072] Take 1 kg of waste battery powder, in which the nickel, cobalt, manganese and lithium contents are 26.2931%, 4.0768%, 3.5236% and 4.0665% respectively, add 5 L of water at a liquid-solid ratio of 5:1 mL / g, and then add 600 g of 98% sulfuric acid. The temperature is controlled at 70°C and the stirring speed is 350 rpm. The pH is maintained below 1.1 during the reaction. After reacting for 6 hours, low-acid leachate and low-acid leach residue are obtained by filtration. The fluorine content of the low-acid leach residue is 0.6% after testing, and the residual fluorine content is relatively high. The fluorine content of the raw material entering the autoclave cannot be higher than 0.1%, otherwise it will corrode the autoclave.

[0073] The low-acid slag has not been treated with potassium hydroxide solution to remove fluorine, and the fluorine content is high, so it cannot enter the autoclave for the subsequent high-pressure leaching step.

[0074] Comparative Example 2

[0075] A method for recovering nickel, cobalt, manganese, lithium and negative electrode graphite from waste ternary lithium batteries by high-voltage reduction, which differs from Example 1 in that the acid solution concentration in step (1) is relatively low, and comprises the following steps:

[0076] (1) Take 1 kg of waste battery powder, in which the nickel, cobalt, manganese and lithium contents are 26.2931%, 4.0768%, 3.5236% and 4.0665% respectively, add 5 L of water at a liquid-solid ratio of 5:1 mL / g, and then add 400 g of 98% sulfuric acid. The temperature is controlled at 70°C and the stirring speed is 350 rpm. After reacting for 6 hours, filter to obtain low-acid leaching solution and low-acid leaching residue. The low-acid leaching residue has the following contents: Ni 16.69%, Co 3.77%, Mn 5.54% and Li 1.2%.

[0077] (2) Add 1 mol / L potassium hydroxide solution to the low-acid leaching residue at a liquid-solid ratio of 1:3 mL / g to form a slurry, stir at 85 ° C for 3 h to mix evenly, put the mixed slurry into a roasting furnace at a temperature of 900 ° C and a roasting time of 1.5 h. After the roasting is completed, the roasted slag is stirred and washed with 80 ° C pure water for 2 h, filtered and then rinsed with pure water to obtain a roasted washed slag. The fluorine content in the slag is 0.29% after detection, and the residual fluorine content is relatively high. The fluorine content of the raw material entering the autoclave cannot be higher than 0.1%, otherwise it will corrode the autoclave.

[0078] The acid concentration in step (1) is low, and the lithium in the waste battery powder cannot be completely leached. During the roasting process, lithium and fluorine-containing compounds generate lithium fluoride that is insoluble in water, resulting in a large amount of fluorine remaining in the roasting washing residue.

[0079] From the experimental results of Examples 1-3 and Comparative Examples 1-2, it can be seen that the recovery rates of Ni, Co, Mn and Li in Examples 1-3 are all above 99.98%; at the same time, the metal content in the high-pressure leaching slag is extremely low, and battery-grade graphite can be obtained after high-temperature calcination; Comparative Document 1 lacks the potassium hydroxide treatment step, and Comparative Document 2 lacks sufficient lithium extraction by low-acid leaching. The fluorine content of the intermediate products of both is relatively high (0.6% and 0.29%, respectively), which does not meet the standard for entering the autoclave (fluorine content not higher than 0.1%), and therefore the subsequent high-pressure leaching step cannot be carried out.

Claims

1. A method for recovering nickel, cobalt, manganese, lithium and negative electrode graphite by high-voltage reduction of a ternary lithium battery, characterized in that: The following steps are involved: S1: mixing the waste battery powder with the first acid solution for leaching, and obtaining the first acid leaching solution and the first acid leaching residue after solid-liquid separation; S2: mixing the first acid leaching residue obtained in step S1 with alkali solution to prepare pulp, and roasting the pulp once to obtain roasted residue; S3: mixing the roasted slag obtained in step S2 with a second acid solution, leaching under pressure, obtaining a second acid leaching solution and a second acid leaching slag after solid-liquid separation, and performing secondary roasting on the second acid leaching slag to obtain battery-grade graphite powder; Wherein, in step S1, the concentration of the first acid solution is 80-220 g / L, and the liquid-solid ratio of the first acid solution to the waste battery powder is (4-10): 1 mL / g; In step S2, the pulping temperature is 70-100°C; In step S3, the concentration of the second acid solution is 230-500 g / L, and the pressure of the pressurized leaching is 0.4-1.6 MPa.

2. The method for recovering nickel, cobalt, manganese, lithium and negative electrode graphite by high-voltage reduction of a ternary lithium battery according to claim 1, characterized in that: In step S1, the liquid-to-solid ratio of the first acid solution to the waste battery powder is (5-8): 1 mL / g; and / or the stirring speed during the leaching process is 300-500 rpm.

3. The method for recovering nickel, cobalt, manganese, lithium and negative electrode graphite by high-voltage reduction of a ternary lithium battery according to claim 1, characterized in that: In step S1, the first acid solution is a sulfuric acid solution, and the concentration of the first acid solution is 100-200 g / L.

4. The method for recovering nickel, cobalt, manganese, lithium and negative electrode graphite by high-voltage reduction of a ternary lithium battery according to claim 1, characterized in that: In step S1, the leaching time is 3-7 hours; and / or, the pH value is controlled at 1.0-1.5 during the leaching process; and / or, the leaching temperature is 60-90°C.

5. The method for recovering nickel, cobalt, manganese, lithium and negative electrode graphite by high-voltage reduction of a ternary lithium battery according to claim 1, characterized in that: In step S2, the alkali solution is at least one of a sodium hydroxide solution or a potassium hydroxide solution.

6. The method for recovering nickel, cobalt, manganese, lithium and negative electrode graphite by high-voltage reduction of a ternary lithium battery according to claim 1, characterized in that: In step S2, the concentration of the alkali solution is 1-3 mol / L; and / or the liquid-to-solid ratio of the alkali solution to the first acid leaching residue is (1-4): 1 mL / g.

7. The method for recovering nickel, cobalt, manganese, lithium and negative electrode graphite by high-voltage reduction of a ternary lithium battery according to claim 1, characterized in that: In step S2, the stirring speed during the slurrying is 300-500 rpm; and / or the slurrying time is 2-4 hours.

8. The method for recovering nickel, cobalt, manganese, lithium and negative electrode graphite by high-voltage reduction of a ternary lithium battery according to claim 1, characterized in that: In step S2, the environment of the primary calcination is an air atmosphere; and / or the temperature of the primary calcination is 600-1000° C.; and the time of the primary calcination is 0.5-2 h.

9. The method for recovering nickel, cobalt, manganese, lithium and negative electrode graphite by high-voltage reduction of a ternary lithium battery according to claim 1, characterized in that: In step S3, the second acid solution is a sulfuric acid solution, and the concentration of the second acid solution is 250-450 g / L.

10. The method for recovering nickel, cobalt, manganese, lithium and negative electrode graphite by high-voltage reduction of a ternary lithium battery according to claim 1, characterized in that: In step S3, the liquid-to-solid ratio of the second acid solution to the calcined slag is (1-3): 1 mL / g.

11. The method for recovering nickel, cobalt, manganese, lithium and negative electrode graphite by high-voltage reduction of a ternary lithium battery according to claim 1, characterized in that: In step S3, the pressure leaching time is 3-8 hours; and / or the pressure leaching temperature is 110-200°C.

12. The method for recovering nickel, cobalt, manganese, lithium and negative electrode graphite by high-voltage reduction of a ternary lithium battery according to claim 1, characterized in that: In step S3, the second acid leaching liquid is used as the first acid liquid in step S1 to leach the waste battery powder.

13. The method for recovering nickel, cobalt, manganese, lithium and negative electrode graphite by high-voltage reduction of a ternary lithium battery according to claim 1, characterized in that: In step S3, the environment of the secondary calcination is an inert atmosphere; and / or the temperature of the secondary calcination is 2000-3000° C.; and / or the time of the secondary calcination is 20-40 hours.

14. A method for recycling lithium batteries, comprising the steps of the method for recovering nickel, cobalt, manganese, lithium and negative electrode graphite by high-voltage reduction of a ternary lithium battery as described in any one of claims 1 to 13.

15. Application of the method for recovering nickel, cobalt, manganese, lithium and negative electrode graphite by high-voltage reduction of ternary lithium batteries as described in any one of claims 1 to 13 in lithium battery recovery.

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