Method for high-pressure reduction recovery of nickel-cobalt-manganese lithium and negative electrode graphite of ternary lithium battery

Abstract

The disclosure provides a method for recovering nickel, cobalt, manganese and lithium and negative electrode graphite from ternary lithium battery high-pressure reduction, which comprises the following steps: low-acid leaching of waste battery powder, mixing the low-acid residue obtained after solid-liquid separation with alkali liquor to prepare pulp, high-pressure leaching of the calcined residue obtained after one-time calcination of the pulp, and two-time calcination of the high-pressure leaching residue obtained after solid-liquid separation to obtain battery-grade graphite powder.

Description

TECHNICAL FIELD

[0001] The present disclosure belongs to the technical field of valuable metal resource recycling, and particularly relates to a method for recovering nickel, cobalt, manganese and lithium and negative electrode graphite from ternary lithium batteries through high-pressure reduction. BACKGROUND

[0002] In recent years, the new energy automobile industry has developed rapidly, and a large amount of solid waste-waste lithium ion batteries has also been generated. Waste lithium ion batteries usually contain a large amount of organic harmful pollutants and heavy metal inorganic compounds, and improper disposal will pose a serious threat to human health, the environment and the biological population. The heavy metals and negative electrode graphite in waste batteries have recycling value because they can be reused in the manufacture of new energy materials, thereby reducing environmental pollution and generating good economic benefits. Waste ternary lithium ion batteries contain a large amount of valuable metals such as nickel, cobalt, manganese and lithium, and recycling them is beneficial to environmental protection and economic benefits. In addition, the continuous decrease of natural graphite resources and the rapid increase of the price of artificial graphite make it particularly important to effectively recover the negative electrode graphite in waste batteries. Therefore, waste battery recycling technology with high efficiency and high recovery rate will become a hot spot in recent years.

[0003] The current industrial process for recycling valuable metals in waste batteries is mainly as follows: under normal pressure, nickel, cobalt, manganese and lithium in battery powder are recovered in the form of nickel sulfate, cobalt sulfate, manganese sulfate and lithium sulfate by adding sulfuric acid and hydrogen peroxide. This conventional method has low recovery efficiency, and the addition of hydrogen peroxide will cause the phenomenon of tank eruption, increasing the safety risk of on-site operation. Another method is to use a low-acid combined with high-pressure leaching process. However, this method does not take into account two safety hazards. On the one hand, battery powder will inevitably contain fluorine-containing compounds, which come from lithium hexafluorophosphate in the electrolyte or PVDF in the separator. Fluorine will form hydrofluoric acid with hydrogen ions during high-pressure acid leaching. Hydrofluoric acid is a highly corrosive acid that can corrode the autoclave, causing safety hazards and increasing subsequent maintenance costs. On the other hand, battery powder also contains aluminum foil and other substances. If these elemental metals are not treated before high-pressure leaching, they will react with acid to generate hydrogen gas during high-pressure leaching, posing an explosion risk. In addition, if the leaching residue containing carbon powder is directly disposed of, the negative electrode carbon powder is not recovered, which not only wastes graphite resources, but also affects the environment and health. Therefore, there is an urgent need to develop a method for efficiently recovering valuable metals and negative electrode graphite from waste ternary lithium batteries. SUMMARY

[0004] The present disclosure aims to at least solve one of the technical problems existing in the prior art. To this end, the present disclosure proposes a method for recovering nickel, cobalt, manganese and lithium and negative electrode graphite from ternary lithium batteries through high-pressure reduction.

[0005] According to a first aspect of the present disclosure, a method for high-pressure reduction and recovery of nickel-cobalt-manganese lithium and negative electrode graphite from ternary lithium batteries is provided, comprising the following steps:

[0006] S1: mixing and leaching waste battery powder with first acid liquor, and obtaining first acid leaching liquor and first acid leaching residue after solid-liquid separation;

[0007] S2: mixing and pulping the first acid leaching residue obtained in step S1 with alkali liquor, and obtaining calcined residue after one-time calcination of the pulp;

[0008] S3: mixing and pressure leaching the calcined residue obtained in step S2 with second acid liquor, and obtaining second acid leaching liquor and second acid leaching residue after solid-liquid separation, and obtaining battery-grade graphite powder after two-time calcination of the second acid leaching residue;

[0009] In step S1, the concentration of the first acid liquor is 80-220 g / L, and the liquid-solid ratio of the first acid liquor to the waste battery powder is (4-10): 1 mL / g;

[0010] In step S2, the pulping temperature is 70-100°C;

[0011] In step S3, the concentration of the second acid liquor is 230-500 g / L, and the pressure of the pressure leaching is 0.4-1.6 MPa.

[0012] In some embodiments, in step S1, the waste battery powder is obtained by discharging, disassembling and crushing the waste ternary lithium battery.

[0013] In some embodiments, in step S1, the liquid-solid ratio of the first acid liquor to the waste battery powder is (5-8): 1 mL / g; and / or, the stirring speed during the leaching process is 300-500 rpm.

[0014] In some embodiments, in step S1, the first acid liquor is a sulfuric acid solution, and the concentration of the first acid liquor is 100-200 g / L. Lithium in the battery powder is leached preferentially over nickel, cobalt and manganese, and at the concentration of the first acid liquor, lithium can be efficiently leached out in its entirety, avoiding affecting the subsequent defluorination process.

[0015] In some embodiments, in step S1, the amount of the first acid liquor added is in excess of the content of lithium in the waste battery powder.

[0016] In some embodiments, in step S1, the leaching is carried out under normal pressure.

[0017] In some embodiments, in step S1, the leaching time is 3-7h; and / or, the pH during the leaching is controlled at 1.0-1.5; and / or, the leaching temperature is 60-90℃. After the first acid leaching solution is treated by conventional purification, extraction, etc., a metal solution for preparing a ternary precursor is obtained.

[0018] In some embodiments, in step S2, the alkali solution is at least one of a sodium hydroxide solution or a potassium hydroxide solution.

[0019] In some embodiments, in step S2, the alkali solution is a potassium hydroxide solution. Compared with sodium hydroxide, potassium hydroxide has weaker corrosiveness to some equipment, and the solubility of potassium fluoride is much greater than that of sodium fluoride: 142g / 60℃ for potassium fluoride and 4.7g / 60℃ for sodium fluoride. The formation of water-soluble potassium fluoride with potassium hydroxide is conducive to the removal of fluorine.

[0020] In some embodiments, in step S2, the concentration of the alkali solution is 1-3mol / L; and / or, the liquid-solid ratio of the alkali solution to the first acid leaching residue is (1-4):1mL / g.

[0021] In some embodiments, in step S2, the stirring speed during the pulping is 300-500rpm; and / or, the pulping time is 2-4h.

[0022] In some embodiments, in step S2, the environment of the first roasting is an air atmosphere; and / or, the first roasting temperature is 600-1000℃; and / or, the first roasting time is 0.5-2h. The potassium hydroxide solution in the slurry can promote the reduction of high-valence cobalt and manganese in the first acid leaching residue to low-valence metal oxides during the roasting of the carbon powder; and the potassium hydroxide solution can also react with fluorine-containing compounds in the first acid leaching residue to remove the fluorine-containing compounds.

[0023] The slurry is fully stirred before the first roasting, and the carbon powder will preferentially react with the metal oxides during the roasting; at the same time, since the atmosphere of the first roasting is an air atmosphere, the carbon powder will not reduce the metal elements to elementary substances, avoiding the risk of explosion caused by the reaction of the elementary substances with the acid to generate hydrogen gas during the subsequent high-pressure leaching. The roasting time should not be too long, otherwise the carbon powder will react with oxygen in the air and cause more loss.

[0024] In some embodiments, in step S2, the roasting residue is also washed. The liquid-solid ratio of water to the roasting residue is (2-5):1mL / g; and / or, the washing time is 1-3h; and / or, the washing temperature is 60-90℃.

[0025] 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.

[0026] In some embodiments, in step S3, the liquid-solid ratio of the second acid solution to the roasted slag is (1-3): 1 mL / g.

[0027] In some embodiments, in step S3, the time of the pressure leaching is 3-8 h; and / or, the temperature of the pressure leaching is 110-200℃. The pressure can increase the boiling point of water, thereby increasing the temperature of the pressure leaching. The high temperature can effectively improve the leaching efficiency, and also can leach the high-valence nickel and cobalt possibly contained in the roasted slag.

[0028] In some embodiments, in step S3, the environment of the secondary roasting is an inert atmosphere; and / or, the temperature of the secondary roasting is 2000-3000℃; and / or, the time of the secondary roasting is 20-40 h. The secondary roasting can convert the amorphous carbon material into the graphitized carbon material, thereby improving the recycling rate of the graphite.

[0029] In some embodiments, in the leaching process of step S1 and the pressure leaching process of step S3, the stirring speed is independently 300-500 rpm.

[0030] According to a second aspect of the present disclosure, a method for recycling lithium batteries is provided, which comprises the steps of the method for recycling nickel, cobalt, manganese lithium and negative electrode graphite of ternary lithium batteries by high-pressure reduction according to the first aspect of the present disclosure.

[0031] According to a third aspect of the present disclosure, the method for recycling nickel, cobalt, manganese lithium and negative electrode graphite of ternary lithium batteries by high-pressure reduction according to the first aspect of the present disclosure is applied in recycling lithium batteries.

[0032] According to an embodiment of the present disclosure, at least the following beneficial effects are achieved:

[0033] 1. The present disclosure provides a method for recycling nickel, cobalt, manganese lithium and negative electrode graphite of waste ternary lithium batteries by high-pressure reduction. The first step is low-acid selective lithium extraction. By controlling the amount of acid, all the lithium in the raw material is leached out, as well as a small part of nickel, cobalt and manganese. The leaching of part of the nickel, cobalt and manganese can reduce the burden of subsequent high-pressure leaching. In addition, the surface of aluminum in waste battery powder is often wrapped in a layer of aluminum oxide, which will not be dissolved under the condition of low-acid leaching. In the subsequent high-pressure leaching process, the boiling point of water can be increased by pressure, thereby increasing the leaching temperature. Combined with a higher concentration of acid solution, it can ensure that nickel, cobalt and manganese are completely leached out. The use of a higher concentration of acid solution in high-pressure leaching is also beneficial to reducing the amount of new acid solution added in the subsequent low-acid leaching.

[0034] 2. In the second step of this disclosure, potassium hydroxide solution is added to prepare the slurry. During the high-temperature roasting of the slurry, fluorine-containing compounds react 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, and the solubility of potassium fluoride is much greater than that of lithium fluoride. The presence of lithium in the defluorination process makes it difficult for fluoride to be completely removed. Therefore, the first step of low-acid selective lithium extraction is necessary to avoid the formation of hydrogen fluoride during the subsequent high-pressure leaching process, which would lead to corrosion and damage to the autoclave.

[0035] 3. The present disclosure involves preparing a pulp and roasting the first acid leaching residue with a potassium hydroxide solution, which mainly serves the following four purposes:

[0036] (1) The first acid leaching residue reacts with potassium hydroxide solution under high temperature to remove aluminum / alumina from waste battery powder. The elemental aluminum / alumina reacts with potassium hydroxide to form potassium aluminate, which is soluble in water. The first function is to avoid the reaction of elemental aluminum with acid to generate hydrogen gas during high-pressure leaching, which could cause an explosion risk. The second function is to reduce the load on subsequent impurity removal, such as the removal of iron and aluminum. The reaction equation is as follows:

[0037] 2Al + 2KOH + 2H₂O → 2KAlO₂ + 3H₂

[0038] Al₂O₃ + 2KOH + 2H₂O → 2KAlO₂ + 3H₂O

[0039] (2) The first acid leaching residue reacts with potassium hydroxide solution at high temperature, which can react with fluorine-containing compounds to form potassium fluoride that is easily soluble in water. After washing with water, the potassium fluoride in the residue can be completely removed. Fluorine-containing compounds include PVDF (chemical formula C2H2F2) in the diaphragm and hydrogen fluoride residue from low acid leaching. The reaction equation is as follows:

[0040] C2H2F2(PVDF)+2KOH+O2→2KF+CO2+2H2O

[0041] HF + KOH → KF + H2O

[0042] (3) The high-valence metals in the first acid leaching residue are converted into easily leached low-valence metal oxides by the reduction action of carbon powder, reducing the input cost of reducing agent auxiliary materials. Potassium hydroxide acts as a catalyst, which is beneficial to the reduction reaction. The catalytic mechanism is as follows:

[0043] 2KOH + C → K₂O + CO + H₂

[0044]

[0045]

[0046] K₂O + H₂O → 2KOH

[0047]

[0048] Wherein, the Ni ion in the reactant is in +2 valence state, the Co ion is in +3 valence state, and the Mn ion is in +4 valence state; the Ni, Co and Mn ions in the product are all in +2 valence state.

[0049] (4) Roasting oxidizes the unreacted metal elements in the first acid leaching residue into metal oxides, avoids the generation of hydrogen gas in the high-pressure reaction kettle, and is easy to cause an explosion risk, and the related reaction equations are as follows:

[0050] 2Al + 3H2SO4→ Al2(SO4)3+ 3H2↑

[0051] 4Al + 3O2→ 2Al2O3

[0052] Al2O3+ 3H2SO4→ Al2(SO4)3+ 3H2O

[0053] 4. The second leaching residue of the present disclosure has a very low residual amount of metal, and high-temperature roasting under inert gas can obtain graphitized carbon material, which can be used as battery-grade graphite, solving the problem of difficult recovery of graphite in battery powder leaching residue, and achieving effective recovery and utilization of graphite

[0054] 5. The present disclosure has the advantages of simple process, environmental friendliness, high safety, high economic benefit, high production efficiency and high recovery rate, realizes the resource utilization of waste batteries, and improves the economic benefit. BRIEF DESCRIPTION OF DRAWINGS

[0055] The present disclosure will be further described below in combination with the drawings and examples, in which:

[0056] Figure 1 It is a process flow diagram of Example 1 of the present disclosure. DETAILED DESCRIPTION

[0057] The concept and technical effects of the present disclosure will be described below in combination with examples to fully understand the purpose, features and effects of the present disclosure.

[0058] Example 1

[0059] A method for high-pressure reduction and recovery of nickel, cobalt, manganese and lithium and negative electrode graphite from waste ternary lithium batteries, as shown in Figure 1 , comprising the following steps:

[0060] 1. Take 1 kg of waste battery powder, which contains 26.2931%, 4.0768%, 3.5236%, and 4.0665% of nickel, cobalt, manganese, and lithium, 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. Control the temperature at 70°C, and the stirring speed at 350 rpm. Keep the pH below 1.1 during the reaction. After 6 h of reaction, filter to obtain low-acid leaching solution and low-acid leaching residue. The low-acid leaching solution is used for the preparation of ternary precursors after impurity removal.

[0061] 2. Add 1 mol / L potassium hydroxide solution to the low-acid leaching residue at a liquid-solid ratio of 1:3 mL / g, and mix uniformly at 85°C for 3 h. Put the mixed slurry into a calcination furnace, and control the temperature at 900°C for 1.5 h. After calcination, wash the calcined residue with 80°C pure water for 2 h, and then rinse with pure water after filtration to obtain the calcined and washed residue.

[0062] 3. The calcined and washed residue F contains 0.0001 wt.%. Add 1.5 L of water at a liquid-solid ratio of 3:1 mL / g, and place it in a high-pressure reactor. Then add 500 g of 98% sulfuric acid. Control the temperature at 160°C, and the pressure at 0.8 Mpa. After 3 h of reaction, cool the high-pressure reactor, and filter to obtain high-pressure leaching solution, which is returned to the low-acid leaching as acid solution. After washing the high-pressure leaching residue, graphiteize it at 2000°C for 30 h to obtain battery-grade graphite for sale.

[0063] The leaching results are as follows:

[0064]

[0065] 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 contents of Ni, Co, Mn, and Li therein, and the mass of the high-pressure leaching residue and the contents of Ni, Co, Mn, and Li therein, respectively, calculating the masses of Ni, Co, Mn, and Li in the battery powder raw material and the high-pressure leaching residue, and calculating the recovery rate of each metal element by the ratio of the difference between the two to the mass of the corresponding metal in the battery powder raw material.

[0066] The recovery rate of C is obtained by the following steps: measuring the C content in the battery powder raw material and the high-pressure leaching residue after graphiteization by a carbon-sulfur instrument, and calculating the mass of C in the battery powder raw material and the high-pressure leaching residue after graphiteization according to their masses. The recovery rate of C is the ratio of the mass of C in the high-pressure leaching residue after graphiteization to the mass of C in the battery powder raw material.

[0067] A method for recycling lithium batteries, comprising the steps of the method for high-pressure reduction and recovery of nickel, cobalt, manganese, and lithium and negative electrode graphite from ternary lithium batteries.

[0068] Example 2

[0069] A method for high-pressure reduction and recovery of nickel, cobalt, manganese, and lithium and negative electrode graphite from waste ternary lithium batteries, comprising the following steps:

[0070] 1. Take 1 kg of waste battery powder, wherein the contents of nickel, cobalt, manganese, and lithium 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. Control the temperature at 90°C, and the stirring speed at 300 rpm. Maintain the pH below 1.2 during the reaction. After 5 h of reaction, filter to obtain low-acid leaching solution and low-acid leaching residue. The low-acid leaching solution is subjected to a purification process for ternary precursor preparation.

[0071] 2. Add 3 mol / L potassium hydroxide solution to the low-acid leaching residue at a liquid-solid ratio of 1:2 mL / g, and mix uniformly at 80°C for 3 h. Place the mixed slurry in a calcination furnace, and control the temperature at 900°C. Calcine for 1.5 h. After calcination, wash the calcined residue with 80°C pure water for 2 h, and then rinse with pure water after filtration to obtain calcined and washed residue.

[0072] 3. The calcined and washed residue F contains 0.0002 wt.%. Add 1 L of water at a liquid-solid ratio of 2:1 mL / g, and place it in a high-pressure reactor. Then add 400 g of 98% sulfuric acid. Control the temperature at 180°C, and the pressure at 1 Mpa. After 4 h of reaction, cool the high-pressure reactor, and filter to obtain high-pressure leaching solution, which is returned to the low-acid leaching as acid solution. After washing the high-pressure leaching residue, graphiteize it at 2500°C for 25 h to obtain battery-grade graphite for sale.

[0073] The leaching results are as follows:

[0074]

[0075] A method for recycling lithium batteries, comprising the steps of the above-mentioned method for high-pressure reduction and recovery of nickel, cobalt, manganese, and lithium and negative electrode graphite from waste ternary lithium batteries.

[0076] Example 3

[0077] A method for high-pressure reduction and recovery of nickel, cobalt, manganese, and lithium and negative electrode graphite from waste ternary lithium batteries, comprising the following steps:

[0078] 1. Take 1 kg of waste battery powder, wherein the contents of nickel, cobalt, manganese, and lithium 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. Control the temperature at 90°C, and the stirring speed at 300 rpm. Maintain the pH below 1.2 during the reaction. After 5 h of reaction, filter to obtain low-acid leaching solution and low-acid leaching residue. The low-acid leaching solution is subjected to a purification process for ternary precursor preparation.

[0079] 2. The low-acid leaching residue is added to 2 mol / L potassium hydroxide solution at a liquid-solid ratio of 1:1 mL / g, a slurry is formed, and stirring is performed at 70°C for 2 h to mix uniformly. The uniformly mixed slurry is placed in a calcination furnace, the temperature is 1000°C, and the calcination time is 1 h. After the calcination is completed, the calcined residue is washed with 70°C pure water for 3 h, and then filtered and rinsed with pure water to obtain a calcined and washed residue.

[0080] 3. The calcined and washed residue F content is 0.0001 wt.%, and 600 mL of water is added at a liquid-solid ratio of 1:1 mL / g and placed in a high-pressure reaction kettle. Then, 250 g of 98% sulfuric acid is added, the temperature is controlled at 170°C, the pressure is 0.9 Mpa, and the reaction is performed for 6 h. After the high-pressure kettle temperature is cooled, the obtained high-pressure leaching liquid is filtered and returned to the low-acid leaching as an acid liquid. The high-pressure leaching residue obtained after washing is subjected to graphitization treatment at 3000°C for 20 h to obtain battery-grade graphite for sale.

[0081] The leaching results are as follows:

[0082] Ni Co Mn Li C Feed (%) 28.0455 5.0033 3.9018 7.9602 45.6475 Leach residue (%) 0.0062 0.0086 0.0164 0.0001 93.1837 Recovery (%) 99.98 99.98 99.98 99.99 90.87

[0083] A method for recycling lithium batteries, comprising the steps of the method for high-pressure reduction and recovery of nickel, cobalt, manganese, and lithium and negative electrode graphite from ternary lithium batteries described above.

[0084] Comparative Example 1

[0085] A method for high-pressure reduction and recovery of nickel, cobalt, manganese, and lithium and negative electrode graphite from waste ternary lithium batteries, which is different from Example 1 in that the low-acid leaching residue is not treated with potassium hydroxide solution, and comprises the following steps:

[0086] Take 1 kg of waste battery powder, wherein the contents of nickel, cobalt, manganese, and lithium are 26.2931%, 4.0768%, 3.5236%, and 4.0665%, respectively. 5 L of water is added at a liquid-solid ratio of 5:1 mL / g, and then 600 g of 98% sulfuric acid is added. The temperature is controlled at 70°C, the stirring speed is 350 rpm, the pH is maintained below 1.1 during the reaction, and the reaction is performed for 6 h. The low-acid leaching liquid and low-acid leaching residue are obtained after filtration. The fluorine content of the low-acid leaching residue is 0.6%, which is relatively high. The fluorine content of the raw material entering the high-pressure kettle cannot be higher than 0.1%, otherwise the high-pressure kettle will be corroded.

[0087] The low-acid residue is not treated with potassium hydroxide solution to remove fluorine, and the fluorine content is relatively high, which cannot enter the high-pressure kettle for subsequent high-pressure leaching steps.

[0088] Comparative Example 2

[0089] A method for high-pressure reduction and recovery of nickel, cobalt, manganese, and lithium and negative electrode graphite from waste ternary lithium batteries, which is different from Example 1 in that the acid liquid concentration in step (1) is lower, and comprises the following steps:

[0090] (1)Take 1 kg of waste battery powder, with nickel, cobalt, manganese, lithium content of 26.2931%, 4.0768%, 3.5236%, 4.0665% respectively, add 5L water with liquid-solid ratio of 5:1 mL / g, then add 400g 98% sulfuric acid, control the temperature at 70℃, stirring speed at 350rpm, after 6h reaction, filter to get low-acid leaching solution and low-acid leaching residue, the low-acid residue content is as follows: Ni 16.69%, Co 3.77%, Mn 5.54%, Li 1.2%.

[0091] (2)The low-acid leaching residue is added with 1 mol / L potassium hydroxide solution with liquid-solid ratio of 1:3 mL / g, form slurry, stir at 85℃ for 3h, mix well, put the mixed slurry into the calcination furnace, temperature at 900℃, calcination time for 1.5h, after calcination, wash the calcination residue with 80℃ pure water for 2h, filter and then rinse with pure water, get calcination and washing residue, the fluorine content in the residue is 0.29%, the fluorine residual content is high, the fluorine content of the raw material entering the autoclave cannot be higher than 0.1%, otherwise the autoclave will be corroded.

[0092] The acid concentration in step (1) is low, and the lithium in the waste battery powder cannot be completely leached out, and in the calcination process, lithium reacts with fluorine-containing compounds to form lithium fluoride which is difficult to dissolve in water, resulting in a large amount of fluorine remaining in the calcination and washing residue.

[0093] From the experimental results of examples 1-3 and comparative examples 1-2, the recovery rates of Ni, Co, Mn and Li in examples 1-3 all reach more than 99.98%; at the same time, the metal content in the high-pressure leaching residue is very low, and after high-temperature calcination, battery-grade graphite can be obtained; comparative example 1 lacks the potassium hydroxide treatment step, and comparative example 2 has insufficient lithium extraction by low-acid leaching, and the fluorine content of the intermediate products of the two is relatively high (0.6%, 0.29% respectively), which does not meet the standard for entering the autoclave (fluorine content not higher than 0.1%), so the subsequent high-pressure leaching step cannot be carried out.

Claims

1. A method for high-voltage reduction and recovery of nickel-cobalt-manganese-lithium and negative electrode graphite from ternary lithium batteries, characterized in that, Includes the following steps: S1: The waste battery powder is mixed with the first acid solution for leaching, and after solid-liquid separation, the first acid leaching solution and the first acid leaching residue are obtained. S2: The first acid leaching residue obtained in step S1 is mixed with alkaline solution to make a slurry. The slurry is then roasted once to obtain roasted residue. S3: The calcined residue obtained in step S2 is mixed with the second acid solution, leached under pressure, and after solid-liquid separation, a second acid leaching solution and a second acid leaching residue are obtained. The second acid leaching residue is then calcined a second time to obtain battery-grade graphite powder. In step S1, the first acid solution is a sulfuric acid solution with a concentration of 100-200 g / L and a liquid-to-solid ratio of (4-10):1 mL / g between the first acid solution and the waste battery powder. In step S2, the temperature of the pulp preparation is 70-100℃; the environment for the first roasting is an air atmosphere; the temperature for the first roasting is 600-1000℃; and the time for the first roasting is 0.5-2 hours. In step S3, the concentration of the second acid solution is 230-500 g / L, and the pressure of the pressure leaching is 0.4-1.6 MPa.

2. The method for high-voltage reduction and recovery of nickel-cobalt-manganese-lithium and negative electrode graphite from ternary lithium batteries 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 high-voltage reduction and recovery of nickel, cobalt, manganese, lithium and negative electrode graphite from 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 is controlled at 1.0-1.5 during the leaching process; and / or, the leaching temperature is 60-90°C.

4. The method for high-voltage reduction and recovery of nickel-cobalt-manganese-lithium and negative electrode graphite from ternary lithium batteries according to claim 1, characterized in that, In step S2, the alkaline solution is at least one of sodium hydroxide solution or potassium hydroxide solution.

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

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

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

8. The method for high-voltage reduction and recovery of nickel, cobalt, manganese, lithium and negative electrode graphite from 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 roasted slag is (1-3): 1 mL / g.

9. The method for high-voltage reduction and recovery of nickel, cobalt, manganese, lithium and negative electrode graphite from 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.

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

11. The method for high-voltage reduction and recovery of nickel-cobalt-manganese-lithium and negative electrode graphite from a ternary lithium battery according to claim 1, characterized in that, In step S3, the environment for the secondary roasting is an inert atmosphere; and / or, the temperature for the secondary roasting is 2000-3000℃; and / or, the time for the secondary roasting is 20-40h.

12. A method for recycling lithium batteries, comprising the steps of the high-voltage reduction method for recycling nickel-cobalt-manganese-lithium and negative electrode graphite as described in any one of claims 1-11.

13. The application of the high-voltage reduction method for recovering nickel, cobalt, manganese, lithium and negative electrode graphite from ternary lithium batteries according to any one of claims 1-11 in lithium battery recycling.

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